Structural Analysis of the Pärvie Fault in Northern Scandinavia

NASA Astrophysics Data System (ADS)

Baeckstroem, A.; Rantakokko, N.; Ask, M. V.

2011-12-01

The Pärvie fault is the largest known postglacial fault in the world with a length of about 160 km. The structure has a dominating fault scarp as its western perimeter but in several locations it is rather a system of several faults. The current fault scarps, mainly caused by reverse faulting, are on average, 10-15 m in height and are thought to have been formed during one momentous event near the end of the latest glaciation (the Weichselian, 9,500-115,000 BP ) (Lagerbäck & Sundh, 2008). This information has been learnt from studying deformation features in sediments from the latest glaciation. However, the fault is believed to have been formed as early as the Precambrian, and it has been reactivated repeatedly throughout its history. The earlier history of this fault zone is still largely unknown. Here we present a pre-study to the scientific drilling project "Drilling Active Faults in Northern Europe", that was submitted to the International Continental Scientific Drilling Program (ICDP) in 2009 (Kukkonen et al. 2010) with an ICDP-sponsored workshop in 2010 (Kukkonen et al. 2011). During this workshop a major issue to be addressed before the start of drilling was to reveal whether the fault scarps were formed by one big earthquake or by several small ones (Kukkonen et al. 2011). Initial results from a structural analysis by Riad (1990) have produced information of the latest kinematic event where it is suggested that the latest event coincides with the recent stress field, causing a transpressional effect. The geometrical model suggested for an extensive area of several fault scarps along the structure is the compressive tulip structure. In the southern part, where the fault dips steeply E, the structure is parallel to the foliation of the country rock and earlier breccias, thus indicating a dependence of earlier structures. Modelling of the stress field during the latest glaciation show that a reverse background stress field together with excess pore pressure governs the destabilization of a structure, such as the Pärvie fault, rather than the induced stresses from the weight of ice-sheet (Lund, 2005). This is a presentation of the first part of the structural analysis of the brittle structures around the Pärvie fault in order to evaluate its brittle deformation history and to attempt to constrain the paleostress fields causing these deformations. References Kukkonen, I.T., Olesen, O., Ask, M.V.S., and the PFDP Working Group, 2010. Postglacial faults in Fennoscandia: targets for scientific drilling. GFF, 132:71-81. Kukkonen, I.T., Ask, M.V.S., Olesen, O., 2011. Postglacial Fault Drilling in Northern Europe: Workshop in Skokloster, Sweden. Scientific Drilling, 11, doi:10.2204/iodp.sd.11.08.2011. Lagerbäck, R. & Sundh, M., 2008. Early Holocene faulting and paleoseismicity in northern Sweden. Geological survey of Sweden. Research paper, C 836. 80 p. Lund, B., Schmidt, P., Hieronymus, C., 2009. Stress evolution and fault stability during the Weichselian glacial cycle. Swedish Nuclear Fuel and Waste Management Co., Stockholm. TR-09-15. 106 p. Riad, L., 1990. The Pärvie fault, Northern Sweden, Uppsala University. Research report 63. 48 p

Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Boulton, Carolyn; Menzies, Catriona D.; Toy, Virginia G.; Townend, John; Sutherland, Rupert

2017-01-01

Oblique dextral motion on the central Alpine Fault in the last circa 5 Ma has exhumed garnet-oligoclase facies mylonitic fault rocks from ˜35 km depth. During exhumation, deformation, accompanied by fluid infiltration, has generated complex lithological variations in fault-related rocks retrieved during Deep Fault Drilling Project (DFDP-1) drilling at Gaunt Creek, South Island, New Zealand. Lithological, geochemical, and mineralogical results reveal that the fault comprises a core of highly comminuted cataclasites and fault gouges bounded by a damage zone containing cataclasites, protocataclasites, and fractured mylonites. The fault core-alteration zone extends ˜20-30 m from the principal slip zone (PSZ) and is characterized by alteration of primary phases to phyllosilicate minerals. Alteration associated with distinct mineral phases occurred proximal the brittle-to-plastic transition (T ≤ 300-400°C, 6-10 km depth) and at shallow depths (T = 20-150°C, 0-3 km depth). Within the fault core-alteration zone, fractures have been sealed by precipitation of calcite and phyllosilicates. This sealing has decreased fault normal permeability and increased rock mass competency, potentially promoting interseismic strain buildup.

Faulting processes in active faults - Evidences from TCDP and SAFOD drill core samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janssen, C.; Wirth, R.; Wenk, H. -R.

The microstructures, mineralogy and chemistry of representative samples collected from the cores of the San Andreas Fault drill hole (SAFOD) and the Taiwan Chelungpu-Fault Drilling project (TCDP) have been studied using optical microscopy, TEM, SEM, XRD and XRF analyses. SAFOD samples provide a transect across undeformed host rock, the fault damage zone and currently active deforming zones of the San Andreas Fault. TCDP samples are retrieved from the principal slip zone (PSZ) and from the surrounding damage zone of the Chelungpu Fault. Substantial differences exist in the clay mineralogy of SAFOD and TCDP fault gouge samples. Amorphous material has beenmore » observed in SAFOD as well as TCDP samples. In line with previous publications, we propose that melt, observed in TCDP black gouge samples, was produced by seismic slip (melt origin) whereas amorphous material in SAFOD samples was formed by comminution of grains (crush origin) rather than by melting. Dauphiné twins in quartz grains of SAFOD and TCDP samples may indicate high seismic stress. The differences in the crystallographic preferred orientation of calcite between SAFOD and TCDP samples are significant. Microstructures resulting from dissolution–precipitation processes were observed in both faults but are more frequently found in SAFOD samples than in TCDP fault rocks. As already described for many other fault zones clay-gouge fabrics are quite weak in SAFOD and TCDP samples. Clay-clast aggregates (CCAs), proposed to indicate frictional heating and thermal pressurization, occur in material taken from the PSZ of the Chelungpu Fault, as well as within and outside of the SAFOD deforming zones, indicating that these microstructures were formed over a wide range of slip rates.« less

The DSeis Project: Drilling into Seismogenic zones of M2.0 to M5.5 earthquakes in South African gold mines

NASA Astrophysics Data System (ADS)

Yabe, Y.; Ogasawara, H.; Ito, T.; van Aswegen, G.; Durrheim, R. J.; Cichowicz, A.; Onstott, T. C.; Kieft, T. L.; Boettcher, M. S.; Wiemer, S.; Ziegler, M.; Shapiro, S. A.; Gupta, H. K.; Dight, P.

2017-12-01

The DSeis project under ICDP consists of drilling in three mines; MK, TT and C4 mines. Common scientific targets among them are the stress state and the microstructure in the seismogenic zone. In addition to these targets, specific targets in individual mines are detailed below. A M5.5 earthquake occurred beneath the MK mine on 5 August 2014. The hypocenter of this event was 5km depth from the surface. In contrast to the normal faulting of induced earthquakes in mining horizons (<4km depth), the M5.5 event was a strike-slip one with an N-S striking, sub-vertical nodal plane along which aftershocks aligned. Aftershocks extend up to 3.5km depth. We established a drilling site at 2.8km depth in the mine, from where two boreholes 800m-long penetrate into the areas of high and low aftershock densities. Targets of these drilling are 1) to investigate a depth variation in the stress state from the normal faulting to the strike-slip one, 2) to know what controls the spatial variation in the aftershock activity, and 3) to explore a limit of deep life that might be trapped in Archean sediments. Our site in the TT mine is 50m under the hypocenter of a M3.2 earthquake which occurred on 28 January 2017 at 3.6km depth. Although aftershock activity recorded by the seismic network operated by the mine is low, the source fault looks to extend along or parallel to a pre-existing, N-S striking fault. Three boreholes go through the fault at the hypocenter and the northern and the southern margins of the fault to compare the stress states and the microfracture distributions. Further, monitoring of microseismicity down to M -4 and geochemistry is planned to evaluate how much is a ratio of microseismicity associated with creation of new fractures. In the C4 mine, there was the site of a previous project, in which the microseismicity monitoring and the stress measurement by the CCBO technique were carried out. A M2.8 earthquake occurred 1 year after the CCBO and its hypocenter was only 100m away from the CCBO site. Due to little mining activity in the source region, the stress state just after the M2.8 event should be preserved. We will measure the stress again. Damage zones that evolved quasi-statically were seen by the microseismicity monitoring. Drilling into these zones would provide a clue to see a difference between faults evolved dynamically and quasi-statically.

S-Wave Velocity Structure of the Taiwan Chelungpu Fault Drilling Project (TCDP) Site Using Microtremor Array Measurements

NASA Astrophysics Data System (ADS)

Wu, Cheng-Feng; Huang, Huey-Chu

2015-10-01

The Taiwan Chelungpu Fault Drilling Project (TCDP) drilled a 2-km-deep hole 2.4 km east of the surface rupture of the 1999 Chi-Chi earthquake ( M w 7.6), near the town of Dakeng. Geophysical well logs at the TCDP site were run over depths ranging from 500 to 1,900 m to obtain the physical properties of the fault zones and adjacent damage zones. These data provide good reference material for examining the validity of velocity structures using microtremor array measurement; therefore, we conduct array measurements for a total of four arrays at two sites near the TCDP drilling sites. The phase velocities at frequencies of 0.2-5 Hz are calculated using the frequency-wavenumber ( f- k) spectrum method. Then the S-wave velocity structures are estimated by employing surface wave inversion techniques. The S-wave velocity from the differential inversion technique gradually increases from 1.52 to 2.22 km/s at depths between 585 and 1,710 m. This result is similar to those from the velocity logs, which range from 1.4 km/s at a depth of 597 m to 2.98 km/s at a depth of 1,705 m. The stochastic inversion results are similar to those from the seismic reflection methods and the lithostratigraphy of TCDP-A borehole, comparatively. These results show that microtremor array measurement provides a good tool for estimating deep S-wave velocity structure.

The damage is done: Low fault friction recorded in the damage zone of the shallow Japan Trench décollement

NASA Astrophysics Data System (ADS)

Keren, Tucker T.; Kirkpatrick, James D.

2016-05-01

Fault damage zones record the integrated deformation caused by repeated slip on faults and reflect the conditions that control slip behavior. To investigate the Japan Trench décollement, we characterized the damage zone close to the fault from drill core recovered during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project (JFAST)). Core-scale and microscale structures include phyllosilicate bands, shear fractures, and joints. They are most abundant near the décollement and decrease in density sharply above and below the fault. Power law fits describing the change in structure density with distance from the fault result in decay exponents (n) of 1.57 in the footwall and 0.73 in the hanging wall. Microstructure decay exponents are 1.09 in the footwall and 0.50 in the hanging wall. Observed damage zone thickness is on the order of a few tens of meters. Core-scale structures dip between ~10° and ~70° and are mutually crosscutting. Compared to similar offset faults, the décollement has large decay exponents and a relatively narrow damage zone. Motivated by independent constraints demonstrating that the plate boundary is weak, we tested if the observed damage zone characteristics could be consistent with low-friction fault. Quasi-static models of off-fault stresses and deformation due to slip on a wavy, frictional fault under conditions similar to the JFAST site predict that low-friction fault produces narrow damage zones with no preferred orientations of structures. These results are consistent with long-term frictional weakness on the décollement at the JFAST site.

The IODP NanTroSEIZE Transect: Accomplishments and Future Plans

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Kinoshita, M.; Araki, E.; Byrne, T. B.; Kimura, G.; McNeill, L. C.; Moore, G. F.; Saffer, D. M.; Underwood, M.; Saito, S.

2009-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a decade-long project to investigate the processes and properties that determine the nature of frictional locking, creep and other fault behavior governing seismogenic rupture and tsunamigenesis on a major plate boundary where great subduction earthquakes occur. The main goal of the science plan is to sample and instrument the key faults in several locations across the transition from those dominated by frictionally stable, aseismic processes vs. those hypothesized to be frictionally locked (seismogenic) faults of the megathrust system. The transect includes primary drill sites from the incoming plate, across the outer accretionary complex of the lower slope, to the Kumano forearc basin and underlying up-dip end of the likely locked plate interface. The scale of this project required a division into multiple stages of operations, spanning a number of years and IODP expeditions. From September 2007 through October 2009, the NanTroSEIZE science team has achieved many of its primary goals during 5 expeditions. Completed drill sites to date include penetrations ranging from ~200 m to ~1600 m below the sea floor that have documented the faults and wall rocks of both the frontal thrust and out-of-sequence splay faults in the accretionary system, the sedimentary section of the subducting plate, and the thick forearc basin sedimentary record and underlying older subduction complex in the hanging wall of the main plate interface. Major results include characterization of: the fault zone geology, strain localization, and physical properties shallower than ~ 1 km, the distribution of ambient (and paleo-) stress orientations across the transect, the absence of evidence for focused fluid channeling along the principal shallow fault systems, and the tectonic history of the subduction system. Extensive downhole measurements and a 2-ship VSP have further documented stress, pressure, rock strength, and elastic properties around the boreholes. The first temporary long-term monitoring instruments are now in place in one sealed borehole, recording pore pressure and temperature. The most ambitious aspect of the NanTroSEIZE project remains for the now-scheduled next stage: drilling to ~ 7000 m below the sea bed across the faults of the main plate boundary, then placing long-term monitoring instruments into both deep and shallow sealed borehole observatories - all to test hypotheses of locking, strain accumulation, and interseismic fault processes.

Controls on fault zone structure and brittle fracturing in the foliated hanging wall of the Alpine Fault

NASA Astrophysics Data System (ADS)

Williams, Jack N.; Toy, Virginia G.; Massiot, Cécile; McNamara, David D.; Smith, Steven A. F.; Mills, Steven

2018-04-01

Three datasets are used to quantify fracture density, orientation, and fill in the foliated hanging wall of the Alpine Fault: (1) X-ray computed tomography (CT) images of drill core collected within 25 m of its principal slip zones (PSZs) during the first phase of the Deep Fault Drilling Project that were reoriented with respect to borehole televiewer images, (2) field measurements from creek sections up to 500 m from the PSZs, and (3) CT images of oriented drill core collected during the Amethyst Hydro Project at distances of ˜ 0.7-2 km from the PSZs. Results show that within 160 m of the PSZs in foliated cataclasites and ultramylonites, gouge-filled fractures exhibit a wide range of orientations. At these distances, fractures are interpreted to have formed at relatively high confining pressures and/or in rocks that had a weak mechanical anisotropy. Conversely, at distances greater than 160 m from the PSZs, fractures are typically open and subparallel to the mylonitic or schistose foliation, implying that fracturing occurred at low confining pressures and/or in rocks that were mechanically anisotropic. Fracture density is similar across the ˜ 500 m width of the field transects. By combining our datasets with measurements of permeability and seismic velocity around the Alpine Fault, we further develop the hierarchical model for hanging-wall damage structure that was proposed by Townend et al. (2017). The wider zone of foliation-parallel fractures represents an outer damage zone that forms at shallow depths. The distinct < 160 m wide interval of widely oriented gouge-filled fractures constitutes an inner damage zone. This zone is interpreted to extend towards the base of the seismogenic crust given that its width is comparable to (1) the Alpine Fault low-velocity zone detected by fault zone guided waves and (2) damage zones reported from other exhumed large-displacement faults. In summary, a narrow zone of fracturing at the base of the Alpine Fault's hanging-wall seismogenic crust is anticipated to widen at shallow depths, which is consistent with fault zone flower structure models.

Attitude, movement history, and structure of cataclastic rocks of the Flemington Fault results of core drilling near Oldwick, New Jersey

USGS Publications Warehouse

Burton, W.C.; Ratcliffe, N.M.

1985-01-01

In the summer of 1983, two holes were drilled through the border fault of the Newark basin near Oldwick, New Jersey, in the Gladstone 7.5minute quadrangle. Figure 1A shows the location of the drill site in relation to regional geology and the major faults. The fault drilled in this study connects to the south with the Flemington fault, which trends southwestward across the Newark basin, as shown. To the north, the fault can be traced along the valley that extends towards Mendham, N. J., beyond the limits of exposed Mesozoic rocks, to connect with the Ramapo fault near Morristown N. J. (fig. 1A; Ratcliffe, 1980). For this reason, we use the name "Flemington" for the border fault in the region of the drill site. A detailed map (fig. 1B) shows the local geology along the border fault from Pottersville, N. J. southward to the axis of the Oldwick syncline.

Development of direct dating methods of fault gouges: Deep drilling into Nojima Fault, Japan

NASA Astrophysics Data System (ADS)

Miyawaki, M.; Uchida, J. I.; Satsukawa, T.

2017-12-01

It is crucial to develop a direct dating method of fault gouges for the assessment of recent fault activity in terms of site evaluation for nuclear power plants. This method would be useful in regions without Late Pleistocene overlying sediments. In order to estimate the age of the latest fault slip event, it is necessary to use fault gouges which have experienced high frictional heating sufficient for age resetting. It is said that frictional heating is higher in deeper depths, because frictional heating generated by fault movement is determined depending on the shear stress. Therefore, we should determine the reliable depth of age resetting, as it is likely that fault gouges from the ground surface have been dated to be older than the actual age of the latest fault movement due to incomplete resetting. In this project, we target the Nojima fault which triggered the 1995 Kobe earthquake in Japan. Samples are collected from various depths (300-1,500m) by trenching and drilling to investigate age resetting conditions and depth using several methods including electron spin resonance (ESR) and optical stimulated luminescence (OSL), which are applicable to ages later than the Late Pleistocene. The preliminary results by the ESR method show approx. 1.1 Ma1) at the ground surface and 0.15-0.28 Ma2) at 388 m depth, respectively. These results indicate that samples from deeper depths preserve a younger age. In contrast, the OSL method dated approx. 2,200 yr1) at the ground surface. Although further consideration is still needed as there is a large margin of error, this result indicates that the age resetting depth of OSL is relatively shallow due to the high thermosensitivity of OSL compare to ESR. In the future, we plan to carry out further investigation for dating fault gouges from various depths up to approx. 1,500 m to verify the use of these direct dating methods.1) Kyoto University, 2017. FY27 Commissioned for the disaster presentation on nuclear facilities (Drilling borehole survey at the Nojima fault), Technical Report. (in Japanese)2) T. Fukuchi, 2001, Assessment of fault activity by ESR dating of fault gouge; an example of the 500m core samples drilled into the Nojima Earthquake Fault in Japan. Quaternary Science Reviews, 20, 1005-1008.

Fault zone hydrogeologic properties and processes revealed by borehole temperature monitoring

NASA Astrophysics Data System (ADS)

Fulton, P. M.; Brodsky, E. E.

2015-12-01

High-resolution borehole temperature monitoring can provide valuable insight into the hydrogeologic structure of fault zones and transient processes that affect fault zone stability. Here we report on results from a subseafloor temperature observatory within the Japan Trench plate boundary fault. In our efforts to interpret this unusual dataset, we have developed several new methods for probing hydrogeologic properties and processes. We illustrate how spatial variations in the thermal recovery of the borehole after drilling and other spectral characteristics provide a measure of the subsurface permeability architecture. More permeable zones allow for greater infiltration of cool drilling fluids, are more greatly thermally disturbed, and take longer to recover. The results from the JFAST (Japan Trench Fast Drilling Project) observatory are consistent with geophysical logs, core data, and other hydrologic observations and suggest a permeable damage zone consisting of steeply dipping faults and fractures overlays a low-permeability clay-rich plate boundary fault. Using high-resolution time series data, we have also developed methods to map out when and where fluid advection occurs in the subsurface over time. In the JFAST data, these techniques reveal dozens of transient earthquake-driven fluid pulses that are spatially correlated and consistently located around inferred permeable areas of the fault damage zone. These observations are suspected to reflect transient fluid flow driven by pore pressure changes in response to dynamic and/or static stresses associated with nearby earthquakes. This newly recognized hydrologic phenomenon has implications for understanding subduction zone heat and chemical transport as well as the redistribution of pore fluid pressure which influences fault stability and can trigger other earthquakes.

Seismic and Gravity Data Help Constrain the Stratigraphic and Tectonic History of Offshore New Harbor, Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Speece, M. A.; Pekar, S. F.; Wilson, G. S.; Sunwall, D. A.; Tinto, K. J.

2010-12-01

The ANDRILL (ANtarctic geological DRILLing) Program’s Offshore New Harbor (ONH) Project successfully conducted multi-channel seismic and gravity surveys in 2008 to investigate the stratigraphic and tectonic history of westernmost Southern McMurdo Sound, Ross Sea, Antarctica, during the Greenhouse World (Eocene) into the start of the Icehouse World (Oligocene). Approximately 48 km of multi-channel seismic reflection data were collected on a sea-ice platform east of New Harbor. The seismic survey used and improved upon methods employed successfully by ANDRILL’s surveys in Southern McMurdo Sound (2005) and in Mackay Sea Valley (2007). These methods include using an air gun and snow streamer of gimbaled geophones. Upgrades in the ONH project’s field equipment substantially increased the rate at which seismic data could be acquired in a sea-ice environment compared to all previous surveys. In addition to the seismic survey, gravity data were collected from the sea ice in New Harbor with the aim of defining basin structural controls. Both the seismic and gravity data indicate thick sediment accumulation above the hanging wall of a major range front fault. This clearly identified fault could be the postulated master fault of the Transantarctic Mountains. An approximately 5 km thick sequence of sediments is present east of the CIROS-1 drill hole. CIROS-1 was drilled adjacent to the range front fault and recovered 702 m of sediments that cross the Eocene/Oligocene boundary. The new geophysical data indicate that substantial sediment core below the Eocene/Oligocene boundary could be recovered to the east of CIROS-1 during future drilling. Inshore of the range front fault, the data show fault bounded half grabens with sediment fill thickening eastward against localized normal faults. Modeling of the gravity data, that extends farther inland than the seismic profiles, suggests that over 1 km of sediments could be present locally offshore Taylor Valley. Future drilling of offshore Taylor Valley could help to constrain the East Antarctic Ice Sheet’s contributions to glacial-interglacial cyclicity in southern McMurdo Sound as far back as the middle Miocene. Unfortunately, the 2008 ONH seismic profiles do not extend far enough up Taylor Valley or Ferrar Fjord to fully define drilling targets. As a result, valley parallel seismic profiles are proposed to extend our seismic interpretations inland and substantiate the gravity models.

The shallow boreholes at The AltotiBerina near fault Observatory (TABOO; northern Apennines of Italy)

NASA Astrophysics Data System (ADS)

Chiaraluce, L.; Collettini, C.; Cattaneo, M.; Monachesi, G.

2014-04-01

As part of an interdisciplinary research project, funded by the European Research Council and addressing the mechanics of weak faults, we drilled three 200-250 m-deep boreholes and installed an array of seismometers. The array augments TABOO (The AltotiBerina near fault ObservatOry), a scientific infrastructure managed by the Italian National Institute of Geophysics and Volcanology. The observatory, which consists of a geophysical network equipped with multi-sensor stations, is located in the northern Apennines (Italy) and monitors a large and active low-angle normal fault. The drilling operations started at the end of 2011 and were completed by July 2012. We instrumented the boreholes with three-component short-period (2 Hz) passive instruments at different depths. The seismometers are now fully operational and collecting waveforms characterised by a very high signal to noise ratio that is ideal for studying microearthquakes. The resulting increase in the detection capability of the seismic network will allow for a broader range of transients to be identified.

Scientific Exploration of Induced SeisMicity and Stress (SEISMS)

NASA Astrophysics Data System (ADS)

Savage, Heather M.; Kirkpatrick, James D.; Mori, James J.; Brodsky, Emily E.; Ellsworth, William L.; Carpenter, Brett M.; Chen, Xiaowei; Cappa, Frédéric; Kano, Yasuyuki

2017-11-01

Several major fault-drilling projects have captured the interseismic and postseismic periods of earthquakes. However, near-field observations of faults immediately before and during an earthquake remain elusive due to the unpredictable nature of seismicity. The Scientific Exploration of Induced SeisMicity and Stress (SEISMS) workshop met in March 2017 to discuss the value of a drilling experiment where a fault is instrumented in advance of an earthquake induced through controlled fluid injection. The workshop participants articulated three key issues that could most effectively be addressed by such an experiment: (1) predictive understanding of the propensity for seismicity in reaction to human forcing, (2) identification of earthquake nucleation processes, and (3) constraints on the factors controlling earthquake size. A systematic review of previous injection experiments exposed important observational gaps in all of these areas. The participants discussed the instrumentation and technological needs as well as faults and tectonic areas that are feasible from both a societal and scientific standpoint.

Infrastructure and mechanical properties of a fault zone in sandstone as an outcrop analogue of a potential geothermal reservoir

NASA Astrophysics Data System (ADS)

Bauer, J. F.; Meier, S.; Philipp, S. L.

2013-12-01

Due to high drilling costs of geothermal projects, it is economically sensible to assess the potential suitability of a reservoir prior to drilling. Fault zones are of particular importance, because they may enhance fluid flow, or be flow barriers, respectively, depending on their particular infrastructure. Outcrop analogue studies are useful to analyze the fault zone infrastructure and thereby increase the predictability of fluid flow behavior across fault zones in the corresponding deep reservoir. The main aims of the present study are to 1) analyze the infrastructure and the differences of fracture system parameters in fault zones and 2) determine the mechanical properties of the faulted rocks. We measure fracture frequencies as well as orientations, lengths and apertures and take representative rock samples for each facies to obtain Young's modulus, compressive and tensile strengths in the laboratory. Since fractures reduce the stiffnesses of in situ rock masses we use an inverse correlation of the number of discontinuities to calculate effective (in situ) Young's moduli to investigate the variation of mechanical properties in fault zones. In addition we determine the rebound hardness, which correlates with the compressive strength measured in the laboratory, with a 'Schmidt-Hammer' in the field because this allows detailed maps of mechanical property variations within fault zones. Here we present the first results for a fault zone in the Triassic Lower Bunter of the Upper Rhine Graben in France. The outcrop at Cleebourg exposes the damage zone of the footwall and a clear developed fault core of a NNW-SSE-striking normal fault. The approximately 15 m wide fault core consists of fault gouge, slip zones, deformation bands and host rock lenses. Intensive deformation close to the core led to the formation of a distal fault core, a 5 m wide zone with disturbed layering and high fracture frequency. The damage zone also contains more fractures than the host rock. Fracture frequency and connectivity clearly increase near the fault core where the reservoir permeability may thus be higher, the effective Young's modulus lower. Similarly the Schmidt-Hammer measurements show that the rebound hardness, or the compressive strength, respectively, decreases near the fault core. This Project is part of the Research- and Development Project 'AuGE' (Outcrop Analogue Studies in Geothermal Exploration). Project partners are the companies Geothermal Engeneering GmbH as well as the Universities of Heidelberg and Erlangen. We thank the German Federal Ministry for the Environment, Nature Conversation and Nuclear Safty (BMU) for funding the project in the framework of the 5th Energy Research Program (FKZ: 0325302). Also thanks to the owner of the quarry for the permission to perform our field studies.

Overview of SAFOD Phases 1 and 2: Drilling, Sampling and Measurements in the San Andreas Fault Zone at Seismogenic Depth

NASA Astrophysics Data System (ADS)

Zoback, M. D.; Hickman, S.; Ellsworth, W.

2005-12-01

In this talk we provide an overview of on-site drilling, sampling and downhole measurement activities associated with the first two Phases of the San Andreas Fault Observatory at Depth. SAFOD is located at the transition between the creeping and locked sections of the fault, 9 km NW of Parkfield, CA. A 2.1 km deep vertical pilot hole was drilled at the site in 2002. The SAFOD main borehole was drilled vertically to a depth of 1.5 km and then deviated at an average angle of 55° to vertical, passing beneath the surface trace of the San Andreas fault, 1.8 km to the NW at a depth of 3.2 km. Repeating microearthquakes on the San Andreas define the main active fault trace at depth, as well as a secondary active fault about 250 m to the SW (i.e., closer to SAFOD). The hole was rotary drilled, comprehensive cuttings were obtained and a real-time analysis of gases in the drilling mud was carried out. Spot cores were obtained at three depths (at casing set points) in the shallow granite and deeper sedimentary rocks penetrated by the hole, augmented by over fifty side-wall cores. Continuous coring of the San Andreas Fault Zone will be carried out in Phase 3 of the project in the summer of 2007. In addition to sampling mud gas, discrete fluid and gas samples were obtained at several depths for geochemical analysis. Real-time geophysical measurements were made while drilling through most of the San Andreas Fault Zone. A suite of "open hole" geophysical measurements were also made over essentially the entire depth of the hole. Construction of the multi-component SAFOD observatory is well underway, with a seismometer and tiltmeter operating at 1 km depth in the pilot hole and a fiber-optic laser strainmeter cemented behind casing in the main hole. A seismometer deployed at depth in the hole between Phases 1 and 2 detected one of the target earthquakes. A number of surface-to-borehole seismic experiments have been carried out to characterize seismic velocities and structures at depth, including deployment of an 80-level, 240-component seismic array in SAFOD in the spring of 2005. With knowledge of P- and S-wave velocities obtained from the geophysical measurements in conjunction with downhole recordings of the SAFOD target earthquake, it appears that the seismically active main trace of the fault is on the order of 400 m SW of the surface trace, in proximity to several candidate zones of particularly anomalous geophysical properties. Observations of casing deformation to be made over the next several years, as well as monitoring of the microearthquakes using seismometers directly within the fault zone, will pinpoint the exact location of this and other active fault traces prior to continuous coring in Phase 3. As will be elaborated in detail by the presentations of the SAFOD science team at this meeting, the activities carried out as part of Phases 1 and 2 of SAFOD lay the ground work for years of exciting research in earthquake physics, fault-rock geology, rock mechanics and the role of fluids and gases in faulting and earthquake generation.

Characterizing the Inner Accretionary Prism of the Nankai Trough with 3D Seismic and Logging While Drilling at IODP Site C0002

NASA Astrophysics Data System (ADS)

Boston, B.; Moore, G. F.; Jurado, M. J.; Sone, H.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

2014-12-01

The deeper, inner parts of active accretionary prisms have been poorly studied due the lack of drilling data, low seismic image quality and typically thick overlying sediments. Our project focuses on the interior of the Nankai Trough inner accretionary prism using deep scientific drilling and a 3D seismic cube. International Ocean Discovery Program (IODP) Expedition 348 extended the existing riser hole to more than 3000 meters below seafloor (mbsf) at Site C0002. Logging while drilling (LWD) data included gamma ray, resistivity, resistivity image, and sonic logs. LWD analysis of the lower section revealed on the borehole images intense deformation characterized by steep bedding, faults and fractures. Bedding plane orientations were measured throughout, with minor gaps at heavily deformed zones disrupting the quality of the resistivity images. Bedding trends are predominantly steeply dipping (60-90°) to the NW. Interpretation of fractures and faults in the image log revealed the existence of different sets of fractures and faults and variable fracture density, remarkably high at fault zones. Gamma ray, resistivity and sonic logs indicated generally homogenous lithology interpretation along this section, consistent with the "silty-claystone" predominant lithologies described on cutting samples. Drops in sonic velocity were observed at the fault zones defined on borehole images. Seismic reflection interpretation of the deep faults in the inner prism is exceedingly difficult due to a strong seafloor multiple, high-angle bedding dips, and low frequency of the data. Structural reconstructions were employed to test whether folding of seismic horizons in the overlying forearc basin could be from an interpreted paleothrust within the inner prism. We used a trishear-based restoration to estimate fault slip on folded horizons landward of C0002. We estimate ~500 m of slip from a steeply dipping deep thrust within the last ~0.9 Ma. Folding is not found in the Kumano sediments near C0002, where normal faults and tilting dominate the modern basin deformation. Both logging and seismic are consistent in characterizing a heavily deformed inner prism. Most of this deformation must have occurred during or before formation of the overlying modern Kumano forearc basin sediments.

The Italian drilling project of the Mont Blanc road tunnel in the late fifties: an example of no geological care and lack of ethics in carrying out a big work.

NASA Astrophysics Data System (ADS)

Gosso, Guido; Croce, Giuseppe; Matteucci, Ruggero; Peppoloni, Silvia; Piacente, Sandra; Wasowski, Janusz

2013-04-01

In the first decade after the Second World War Italy was rushing to recover a positive role among European countries; basic needs as road communications with European neighbours became main priorities. The necessity of a rapid connection with South-eastern France, a subject already debated between the two nations over more than 50 years, appeared then on first line; the two countries convened on a joint investment for the construction of a tunnel across the international border of Mont Blanc, along the shortest track between Courmayeur and Chamonix. The political agreements were in favour of the quickest start of the drilling operations and such obligation imposed on the Italian side an impoverishment of the project content, specially concerning geological issues. No surveys were performed on fracture systems, cataclastic zones and faults, on the few rock ridges standing above the tunnel line and outcropping through thick talus cones, moraines, ice tongues and their related ice plateaus. Metasediments, migmatites and poorly foliated granites were to be drilled. Three Italian academics were allowed by the drilling company to track the working progress and collect rocks for comparison with other Alpine types; they mapped the lithology and the fault zonesall along the freshly excavated tunnel; the results of such survey appeared after the end of works. Geologists from Florence University published the surface granite faulting pattern 20 years after the road tunnel became operative. Such geological cares could have located the risky zones in time for the tunnel project, mitigating the catastrophic effects of sudden drainage of subglacial water from the Vallée Blanche ice plateau (Ghiacciaio del Gigante) at progression 3800m, that caused dramatic accidents and affected negatively the economy of the drilling. Also the wallrock temperature drops, measured during the drill, should have warned the company management on the location of dangerous fracture zones. Anxiety of national renaissance probably committed the Italian team to a fast conclusion, skipping attention from geological urgencies. But did attitudes change since then? This late episode gives us the opportunity to reflect on the necessity of making politicians seriously aware of the importance of geology when carrying out big works, to impose by law more effective policies and make interrelations between the involved professionals mandatory. Firm geoethic principles should guide choices and decisions in projects of great environmental impact.

High-resolution seismic survey for the characterization of planned PIER-ICDP fluid-monitoring sites in the Eger Rift zone

NASA Astrophysics Data System (ADS)

Simon, H.; Buske, S.

2017-12-01

The Eger Rift zone (Czech Republic) is a intra-continental non-volcanic region and is characterized by outstanding geodynamic activities, which result in earthquake swarms and significant CO2 emanations. Because fluid-induced stress can trigger earthquake swarms, both natural phenomena are probably related to each other. The epicentres of the earthquake swarms cluster at the northern edge of the Cheb Basin. Although the location of the cluster coincides with the major Mariánské-Lázně Fault Zone (MLFZ) the strike of the focal plane indicates another fault zone, the N-S trending Počátky-Plesná Zone (PPZ). Isotopic analysis of the CO2-rich fluids revealed a significant portion of upper mantle derived components, hence a magmatic fluid source in the upper mantle was postulated. Because of these phenomena, the Eger Rift area is a unique site for interdisciplinary drilling programs to study the fluid-earthquake interaction. The ICDP project PIER (Probing of Intra-continental magmatic activity: drilling the Eger Rift) will set up an observatory, consisting of five monitoring boreholes. In preparation for the drilling, the goal of the seismic survey is the characterization of the projected fluid-monitoring drill site at the CO2 degassing mofette field near Hartoušov. This will be achieved by a 6 km long profile with dense source and receiver spacing. The W-E trending profile will cross the proposed drill site and the surface traces of MLFZ and PPZ. The outcome of the seismic survey will be a high-resolution structural image of potential reflectors related to these fault zones. This will be achieved by the application of advanced pre-stack depth migration methods and a detailed P-wave velocity distribution of the area obtained from first arrival tomography. During interpretation of the seismic data, a geoelectrical resistivity model, acquired along the same profile line, will provide important constraints, especially with respect to fluid pathways.

Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Final report, March 1996--September 1998

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.

1998-12-01

This project was designed to analyze the structure of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas to suggest ways in which oil recovery can be improved. The Eutaw Formation comprises 7 major flow units and is dominated by low-resistivity, low-contrast play that is difficult to characterize quantitatively. Selma chalk produces strictly from fault-related fractures that were mineralized as warm fluid migrated from deep sources. Resistivity, dipmeter, and fracture identification logs corroborate that deformation is concentrated in the hanging-wall drag zones. New area balancing techniques were developed to characterize growth strata and confirm that strain is concentrated inmore » hanging-wall drag zones. Curvature analysis indicates that the faults contain numerous fault bends that influence fracture distribution. Eutaw oil is produced strictly from footwall uplifts, whereas Selma oil is produced from fault-related fractures. Clay smear and mineralization may be significant trapping mechanisms in the Eutaw Formation. The critical seal for Selma reservoirs, by contrast, is where Tertiary clay in the hanging wall is juxtaposed with poorly fractured Selma chalk in the footwall. Gilbertown Field can be revitalized by infill drilling and recompletion of existing wells. Directional drilling may be a viable technique for recovering untapped oil from Selma chalk. Revitalization is now underway, and the first new production wells since 1985 are being drilled in the western part of the field.« less

Determination of three-dimensional stress orientations in the Wenchuan earthquake Fault Scientific Drilling (WFSD) hole-1: A preliminary result by anelastic strain recovery measurements of core samples

NASA Astrophysics Data System (ADS)

Cui, J.; Lin, W.; Wang, L.; Tang, Z.; Sun, D.; Gao, L.; Wang, W.

2010-12-01

A great and destructive earthquake (Ms 8.0; Mw 7.9), Wunchuan earthquake struck on the Longmen Shan foreland trust zone in Sichuan province, China on 12 May 2008 (Xu et al., 2008; Episodes, Vol.31, pp.291-301). As a rapid response scientific drilling project, Wenchuan earthquake Fault Scientific Drilling (WFSD) started on 6 November 2008 shorter than a half of year from the date of earthquake main shock. The first pilot borehole (hole-1) has been drilled to the target depth (measured depth 1201 m MD, vertical depth 1179 m) at Hongkou, Dujianyan, Sichuan and passed through the main fault of the earthquake around 589 m MD. We are trying to determine three dimensional in-situ stress states in the WFSD boreholes by a core-based method, anelastic strain recovery (ASR) method (Lin et al., 2006; Tectonophysics, Vol4.26, pp.221-238). This method has been applied in several scientific drilling projects (TCDP: Lin et al., 2007; TAO, Vol.18, pp.379-393; NanTtoSEIZE: Byrne et al., 2009; GRL, Vol.36, L23310). These applications confirm the validity of using the ASR technique in determining in situ stresses by using drilled cores. We collected total 15 core samples in a depth range from 340 m MD to 1180 m MD, approximately for ASR measurements. Anelastic normal strains, measured every ten minutes in nine directions, including six independent directions, were used to calculate the anelastic strain tensors. The data of the ASR tests conducted at hole-1 is still undergoing analysis. As a tentative perspective, more than 10 core samples showed coherent strain recovery over one - two weeks. However, 2 or 3 core samples cannot be re-orientated to the global system. It means that we cannot rink the stress orientation determined by the core samples to geological structure. Unfortunately, a few core samples showed irregular strain recovery and were not analyzed further. The preliminary results of ASR tests at hole-1 show the stress orientations and stress regime changes a lot with the depth.

New access to the deep interior of the Nankai accretionary complex and comprehensive characterization of subduction inputs and recent mega splay fault activity (IODP-NanTroSEIZE Expedition 338)

NASA Astrophysics Data System (ADS)

Strasser, Michael; Moore, Gregory F.; Kanagawa, Kyuichi; Dugan, Brandon; Fabbri, Olivier; Toczko, Sean; Maeda, Lena

2013-04-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a coordinated, multi-expedition Integrated Ocean Drilling Program (IODP) drilling project designed to investigate fault mechanics and seismogenesis along subduction megathrusts through direct sampling, in situ measurements, and long-term monitoring in conjunction with allied laboratory and numerical modeling studies. IODP Expedition 338 (1 October 2012 - 13 January 2013), extended riser Hole C0002F from 856 meters below the sea floor (mbsf) to 2005 mbsf. Site C0002 is the centerpiece of the NanTroSEIZE project, and is planned to be deepened to eventually reach the seismogenic fault zone during upcoming drilling expeditions. The original Exp. 338 operational plan to case the hole to 3600 mbsf had to be revised as sudden changes in sea conditions resulted in damage to parts of the riser system, thus the hole was suspended at 2005 mbsf but left for future re-entry. The revised operation plan included additional riserless logging and coring of key targets not sampled during previous NanTroSEIZE expeditions, but relevant to comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution and the recent activity of the shallow mega splay fault zone system and submarine landslides. Here we present preliminary results from IODP Exp. 338: Logging While Drilling (LWD), mud gas monitoring and analysis on cuttings from the deep riser hole characterize two lithological units within the internal accretionary prism, separated by a prominent fault zone at ~1640 mbsf. Internal style of deformation, downhole increase of thermogenically formed formation gas and evidence for mechanical compaction and cementation document a complex structural evolution and provide unprecedented insights into the mechanical state and behavior of the wedge at depth. Additionally, multiple samples of the unconformity between the Kumano Basin and accretionary prism at Site C0002 shed new light on this debatable unconformity boundary and suggest variable erosional processes active on small spatial scales. Results from riserless drilling at input Site C0012 include 178.7 m of detailed LWD characterization of the oceanic basement, indicating an upper ~100 m zone of altered pillow basalts and sheet flow deposits, and a lower, presumably less altered basement unit without indication for interlayered sediment horizons. Low angle faults identified in X-ray Computed Tomography images and structural investigation on cores from Site C0022, located in the slope basin immediately seaward of the megasplay fault zone, indicate splay-fault-related, out-of-sequence thrusting within slope basin sediments and shed new light on recent activity of the megasplay. Lastly, Exp. 338 added additional coring to improve our understanding of submarine landslides in the slope basins seaward of the splay fault and yields new LWD data to characterize in situ internal structures and properties of mass-transport deposits as it relates to the dynamics and kinematics of submarine landslides.

Imaging the Alpine Fault: preliminary results from a detailed 3D-VSP experiment at the DFDP-2 drill site in Whataroa, New Zealand

NASA Astrophysics Data System (ADS)

Lay, Vera; Bodenburg, Sascha; Buske, Stefan; Townend, John; Kellett, Richard; Savage, Martha; Schmitt, Douglas; Constantinou, Alexis; Eccles, Jennifer; Lawton, Donald; Hall, Kevin; Bertram, Malcolm; Gorman, Andrew

2017-04-01

The plate-bounding Alpine Fault in New Zealand is an 850 km long transpressive continental fault zone that is late in its earthquake cycle. The Deep Fault Drilling Project (DFDP) aims to deliver insight into the geological structure of this fault zone and its evolution by drilling and sampling the Alpine Fault at depth. Previously analysed 2D reflection seismic data image the main Alpine Fault reflector at a depth of 1.5-2.2 km with a dip of approximately 48° to the southeast below the DFDP-2 borehole. Additionally, there are indications of a more complex 3D fault structure with several fault branches which have not yet been clearly imaged in detail. For that reason we acquired a 3D-VSP seismic data set at the DFDP-2 drill site in January 2016. A zero-offset VSP and a walk-away VSP survey were conducted using a Vibroseis source. Within the borehole, a permanently installed "Distributed Acoustic Fibre Optic Cable" (down to 893 m) and a 3C Sercel slimwave tool (down to 400 m) were used to record the seismic wavefield. In addition, an array of 160 three-component receivers with a spacing of 10 m perpendicular and 20 m parallel to the main strike of the Alpine Fault was set up and moved successively along the valley to record reflections from the main Alpine Fault zone over a broad depth range and to derive a detailed 3D tomographic velocity model in the hanging wall. We will show a detailed 3D velocity model derived from first-arrival traveltime tomography. Subsets of the whole data set were analysed separately to estimate the corresponding ray coverage and the reliability of the observed features in the obtained velocity model. By testing various inversion parameters and starting models, we derived a detailed near-surface velocity model that reveals the significance of the old glacial valley structures. Hence, this new 3D model improves the velocity model derived previously from a 2D seismic profile line in that area. Furthermore, processing of the dense 3C data shows clear reflections on both inline and crossline profiles. Correlating single reflection events enables us to identify the origin of reflections recorded in the data and reveal their 3D character. This array data gives strong evidence for reflections coming from the side, possibly from the steeply dipping valley flanks. Finally, the data will be processed using advanced seismic imaging methods to derive a detailed structural image of the valley and the fault zone at depth. Thus, the results will provide a detailed basis for a seismic site characterization at the DFDP-2 drill site, that will be of crucial importance for further structural and geological investigations of the architecture of the Alpine Fault in this area.

Geology of drill hole UE25p No. 1: A test hole into pre-Tertiary rocks near Yucca Mountain, southern Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, M.D.; Waddell, S.J.; Vick, G.S.

1986-12-31

Yucca Mountain in southern Nye County, Nevada, has been proposed as a potential site for the underground disposal of high-level nuclear waste. An exploratory drill hole designated UE25p No. 1 was drilled 3 km east of the proposed repository site to investigate the geology and hydrology of the rocks that underlie the Tertiary volcanic and sedimentary rock sequence forming Yucca Mountain. Silurian dolomite assigned to the Roberts Mountain and Lone Mountain Formations was intersected below the Tertiary section between a depth of approximately 1244 m (4080 ft) and the bottom of the drill hole at 1807 m (5923 ft). Thesemore » formations are part of an important regional carbonate aquifer in the deep ground-water system. Tertiary units deeper than 1139 m (3733 ft) in drill hole UE25p No. 1 are stratigraphically older than any units previously penetrated by drill holes at Yucca Mountain. These units are, in ascending order, the tuff of Yucca Flat, an unnamed calcified ash-flow tuff, and a sequence of clastic deposits. The upper part of the Tertiary sequence in drill hole UE25p No. 1 is similar to that found in other drill holes at Yucca Mountain. The Tertiary sequence is in fault contact with the Silurian rocks. This fault between Tertiary and Paleozoic rocks may correlate with the Fran Ridge fault, a steeply westward-dipping fault exposed approximately 0.5 km east of the drill hole. Another fault intersects UE25p No. 1 at 873 m (2863 ft), but its surface trace is concealed beneath the valley west of the Fran Ridge fault. The Paintbrush Canyon fault, the trace of which passes less than 100 m (330 ft) east of the drilling site, intersects drill hole UE25p No. 1 at a depth of approximately 78 m (255 ft). The drill hole apparently intersected the west flank of a structural high of pre-Tertiary rocks, near the eastern edge of the Crater Flat structural depression.« less

Structural Characterization of the Foliated-Layered Gabbro Transition in Wadi Tayin of the Samail Ophiolite, Oman; Oman Drilling Project Holes GT1A and GT2A

NASA Astrophysics Data System (ADS)

Deans, J. R.; Crispini, L.; Cheadle, M. J.; Harris, M.; Kelemen, P. B.; Teagle, D. A. H.; Matter, J. M.; Takazawa, E.; Coggon, J. A.

2017-12-01

Oman Drilling Project Holes GT1A and GT2A were drilled into the Wadi Tayin massif, Samail ophiolite and both recovered ca. 400 m of continuous core through a section of the layered gabbros and the foliated-layered gabbro transition. Hole GT1A is cut by a discrete fault system including localized thin ultracataclastic fault zones. Hole GT2A is cut by a wider zone of brittle deformation and incipient brecciation. Here we report the structural history of the gabbros reflecting formation at the ridge to later obduction. Magmatic and high temperature history- 1) Both cores exhibit a pervasive, commonly well-defined magmatic foliation delineated by plagioclase, olivine and in places clinopyroxene. Minor magmatic deformation is present. 2) The dip of the magmatic foliation varies cyclically, gradually changing dip by 30o from gentle to moderate over a 50 m wavelength. 3) Layering is present throughout both cores, is defined by changes in mode and grain size ranging in thickness from 2 cm to 3 m and is commonly sub-parallel to the foliation. 4) There are no high temperature crystal-plastic shear zones in the core. Key observations include: no simple, systematic shallowing of dip with depth across the foliated-layered gabbro transition and layering is continuous across this transition. Cyclic variation of magmatic foliation dip most likely reflects the process of plate separation at the ridge axis. Near-axis faulting- i) On or near-axis structures consist of epidote-amphibole bearing hydraulic breccias and some zones of intense cataclasis with intensely deformed epidote and seams of clay and chlorite accompanied by syntectonic alteration of the wall rock. Early veins are filled with amphibole, chlorite, epidote, and anhydrite. ii) The deformation ranges from brittle-ductile, causing local deflection of the magmatic foliation, to brittle offset of the foliation and core and mantle structures in anhydrite veins. iii) The prevalent sense of shear is normal and slickenfibers indicate oblique offset. Obduction related faulting- i) Low temperature brittle faults and veins with laumontite, clay, and gypsum crosscut all structures. ii) Faults show a reverse sense of shear and crosscut, possibly reactivate, normal faults. Our observations suggest formation of reverse faults and late veins during obduction of the ophiolite.

Comparative study of two active faults in different stages of the earthquake cycle in central Japan -The Atera fault (with 1586 Tensho earthquake) and the Nojima fault (with 1995 Kobe earthquake)-

NASA Astrophysics Data System (ADS)

Matsuda, T.; Omura, K.; Ikeda, R.

2003-12-01

National Research Institute for Earth Science and Disaster Prevention (NIED) has been conducting _gFault zone drilling_h. Fault zone drilling is especially important in understanding the structure, composition, and physical properties of an active fault. In the Chubu district of central Japan, large active faults such as the Atotsugawa (with 1858 Hietsu earthquake) and the Atera (with 1586 Tensho earthquake) faults exist. After the occurrence of the 1995 Kobe earthquake, it has been widely recognized that direct measurements in fault zones by drilling. This time, we describe about the Atera fault and the Nojima fault. Because, these two faults are similar in geological situation (mostly composed of granitic rocks), so it is easy to do comparative study of drilling investigation. The features of the Atera fault, which have been dislocated by the 1586 Tensho earthquake, are as follows. Total length is about 70 km. That general trend is NW45 degree with a left-lateral strike slip. Slip rate is estimated as 3-5 m / 1000 years. Seismicity is very low at present and lithologies around the fault are basically granitic rocks and rhyolite. Six boreholes have been drilled from the depth of 400 m to 630 m. Four of these boreholes (Hatajiri, Fukuoka, Ueno and Kawaue) are located on a line crossing in a direction perpendicular to the Atera fault. In the Kawaue well, mostly fractured and alternating granitic rock continued from the surface to the bottom at 630 m. X-ray fluorescence analysis (XRF) is conducted to estimate the amount of major chemical elements using the glass bead method for core samples. The amounts of H20+ are about from 0.5 to 2.5 weight percent. This fractured zone is also characterized by the logging data such as low resistivity, low P-wave velocity, low density and high neutron porosity. The 1995 Kobe (Hyogo-ken Nanbu) earthquake occurred along the NE-SW-trending Rokko-Awaji fault system, and the Nojima fault appeared on the surface on Awaji Island when this rupture occurred. It is more than 10 km long with 1-2 m offset along the Nojima fault. About one year after the earthquake, NIED drilled a borehole (the Hirabayashi NIED borehole) and penetrated the Nojima fault. The Hirabayashi NIED borehole was drilled to a depth of 1838 m and recovered the drill core. The main types of rock intersected by the borehole are granodiorite and cataclastic fault rocks. Three fracture zones were recognized in cores at approximate depth of 1140 m, 1300 m and 1800 m. There is remarkable foliated blue-gray gouge at a depth of 1140 m. We investigate chemical compositions by XRF analysis in the fracture zone. The amounts of H20+ are about from 1.0 to 15.0 weight percent. We investigate mineral assemblage in both drilling cores by X-ray powder diffraction analysis. From the results, we can_ft recognize so difference between the two faults. But the amount of H2O+ is very different. In the Hirabayashi NIED core at a depth of 1140 m, there is about ten times as much as the average of the Kawaue core. This is probably due to the greater degree of wall-rock fracturing in the fracture zone. We suggest that this characteristic is associated with the fault activity at the time of the 1995 Kobe earthquake and the nature of fluid-rock interactions in the fracture zone.

Calibration of the seismic velocity structure and understanding of the fault formation in the environs of the Orkney M5.5 earthquake, South Africa

NASA Astrophysics Data System (ADS)

Ogasawara, H.; Manzi, M. S.; Durrheim, R. J.; Ogasawara, H.

2017-12-01

In August 2014, the largest seismic event (M5.5) to occur in a South African gold mining district took place near Orkney. The M5.5 event and aftershocks were recorded by strainmeters installed at 3 km depth hundreds of meters above the M5.5 fault, 46 in-mine 4.5Hz triaxial geophone stations at depths of 2-3 km within a hypocentral radius of 2-3 km, and 17 surface strong motion stations (South African Seismograph Network; SANSN) within an epicentral radius of 25 km. Aftershocks were distributed on a nearly vertical plane striking NNW-SSE. The upper edge of this fault was hundreds of meters below the deepest level of the mine. ICDP approved a project "Drilling into seismogenic zones of M2.0-5.5 earthquakes in South African gold mines" to elucidate the details of the events (DSeis; Yabe et al. invited talk in S020 in this AGU). On 1 August 2017 drilling was within a few hundreds of meters of intersecting the M5.5 fault zone. To locate the drilling target accurately it is very important to determine the velocity structure between the seismic events and sensors. We do this by using the interval velocities used to migrate 3D-reflection seismic data that was previously acquired by a mining company to image the gold-bearing reef and any fault structures close to the mining horizon. Less attention was given to the velocities below the mining horizon, as accurate imaging of the geological structure was not as important and very little drilling information was available. We used the known depths of prominent reflectors above the mining horizon to derive the interval velocities needed to convert two-way-travel-time to depth. We constrain the velocity below the mining horizon by comparing the DSeis drilling results with the 3D seismic cube. The geometric data is crucial for the kinematic modeling that Ogasawara et al. (S018 in this AGU) advocates. The efforts will result in a better understanding of the main rupture and aftershocks.

Results and interpretation of exploratory drilling near the Picacho Fault, south-central Arizona

USGS Publications Warehouse

Holzer, Thomas L.

1978-01-01

Modern surface faulting along the Picacho fault, east of Picacho, Arizona, has been attributed to ground-water withdrawal. In September 1977, three exploratory test holes were drilled 5 km east of Picacho and across the Picacho fault to investigate subsurface conditions and the mechanism of the faulting. The holes were logged by conventional geophysical and geologic methods. Piezometers were set in each hole and have been monitored since September 1977. The drilling indicates that the unconsolidated alluvium beneath the surface fault is approximately 310 m thick. Drilling and piezometer data and an associated seismic refraction survey indicate that the modern faulting is coincident with a preexisting, high-angle, normal fault that offsets units within the alluvium as well as the underlying bedrock. Piezometer and neutron log data indicate that the preexisting fault behaves as a partial ground-water barrier. Monitoring of the piezometers indicates that the magnitude of the man-induced difference in water level across the preexisting fault is seasonal in nature, essentially disappearing during periods of water-level recovery. The magnitude of the seasonal difference in water level, however, appears to be sufficient to account for the modern fault offset by localized differential compaction caused by a difference in water level across the preexisting fault. In addition, repeated level surveys since September 1977 of bench marks across the surface fault and near the piezometers have indicated fault movement that corresponds to fluctuations of water level.

Permeability and seismic velocity and their anisotropy across the Alpine Fault, New Zealand: An insight from laboratory measurements on core from the Deep Fault Drilling Project phase 1 (DFDP-1)

NASA Astrophysics Data System (ADS)

Allen, M. J.; Tatham, D.; Faulkner, D. R.; Mariani, E.; Boulton, C.

2017-08-01

The Alpine Fault, a transpressional plate boundary between the Australian and Pacific plates, is known to rupture quasiperiodically with large magnitude earthquakes (Mw 8). The hydraulic and elastic properties of fault zones are thought to vary over the seismic cycle, influencing the nature and style of earthquake rupture and associated processes. We present a suite of laboratory permeability and P (Vp) and S (Vs) wave velocity measurements performed on fault lithologies recovered during the first phase of the Deep Fault Drilling Project (DFDP-1), which sampled principal slip zone (PSZ) gouges, cataclasites, and fractured ultramylonites, with all recovered lithologies overprinted by abundant secondary mineralization, recording enhanced fluid-rock interaction. Core material was tested in three orthogonal directions, orientated relative to the down-core axis and, when present, foliation. Measurements were conducted with pore pressure (H2O) held at 5 MPa over an effective pressure (Peff) range of 5-105 MPa. Permeabilities and seismic velocities decrease with proximity to the PSZ with permeabilities ranging from 10-17 to 10-21 m2 and Vp and Vs ranging from 4400 to 5900 m/s in the ultramylonites/cataclasites and 3900 to 4200 m/s at the PSZ. In comparison with intact country rock protoliths, the highly variable cataclastic structures and secondary phyllosilicates and carbonates have resulted in an overall reduction in permeability and seismic wave velocity, as well as a reduction in anisotropy within the fault core. These results concur with other similar studies on other mature, tectonic faults in their interseismic period.

The Sulcis Storage Project: Status of the First Italian Initiative for Pilot-Scale Geological Sequestration of CO2

NASA Astrophysics Data System (ADS)

Plaisant, A.; Maggio, E.; Pettinau, A.

2016-12-01

The deep aquifer located at a depth of about 1000-1500 m within fractured carbonate in the Sulcis coal basin (South-West Sardinia, Italy) constitutes a potential reservoir to develop a pilot-scale CO2 storage site. The occurrence of several coal mines and the geology of the basin also provide favourable condition to install a permanent infrastructures where advanced CO2 storage technologies can be developed. Overall, the Sulcis project will allow to characterize the Sulcis coal basin (South West Sardinia, Italy) and to develop a permanent infrastructure (know-how, equipment, laboratories, etc.) for advanced international studies on CO2 storage. The research activities are structured in two different phases: (i) site characterization, including the construction of an underground and a fault laboratories and (ii) the installation of a test site for small-scale injection of CO2. In particular, the underground laboratory will host geochemical and geophysical experiments on rocks, taking advantages of the buried environment and the very well confined conditions in the galleries; in parallel, the fault laboratory will be constructed to study CO2 leakage phenomena in a selected fault. The project is currently ongoing and some preliminary results will be presented in this work as well as the structure of the project as a whole. More in detail, preliminary activities comprise: (i) geochemical monitoring; (ii) the minero-petrographycal, physical and geophysical characterization of the rock samples; (iii) the development of both static and dynamic geological models of the reservoir; (iv) the structural geology and fault analysis; (v) the assessment of natural seismicity through a monitoring network (vi) the re-processing and the analysis of the reflection seismic data. Future activities will comprise: (i) the drilling of shallow exploration wells near the faults; (ii) the construction of both the above mentioned laboratories; (iii) drilling of a deep exploration well (1,500 m); (iv) injection tests. Preliminary analyses show that the rocks of the carbonate formation present a low porosity, but the formation is characterized by a good permeability for fractures and karst. The faults are typically sealed and petrophysical properties of caprock and reservoir are spatially heterogeneous.

Upward extension of the Nankai accretionary prism megasplay fault into slope basin strata. Insights from drilling at IODP Expedition 338 Site C0022

NASA Astrophysics Data System (ADS)

Fabbri, O.; Oohashi, K.; Kanagawa, K.; Yamaguchi, A.

2013-12-01

Megasplay faults have been recognized on seismic reflection profiles across several convergent margins in the world. Understanding the behavior of these faults during large to very large inter-plate earthquakes is a major challenge in assessing strong-motion and tsunami hazards at or near subduction zones. One of the goals of the IODP NanTroSEIZE project is to drill across and to obtain data from the megasplay fault crossing the Nankai accretionary prism off Kii peninsula (Kumano transect), SW Japan. This fault is considered to have been activated during the 1944 Tonankai earthquake (Baba et al., 2006 ; Moore et al., 2007). Drilling and coring during IODP Expedition 316 (Expedition 316 Scientists, 2009) showed that the megasplay fault at 300 mbsf at Site C0004 consists in a 60 m thick package of fractured and brecciated rocks. Combined analysis of 3D reflection data in the vicinity of Site C0004 and core data from sites C0004 and C0008 (Strasser et al., 2009 ; Kimura et al., 2011) suggest that the lower boundary of the megasplay fault ceased activity at about 1.55 Ma while its upper boundary has remained active since about 1.95 Ma and probably 1.24 Ma. In order to determine whether the megasplay fault upper boundary crosscuts slope sediments or is sealed by them, drilling at IODP Site C0022 was carried out during Expedition 338. Two 420 m deep holes were drilled: C0022A (LWD) and C0022B (coring). At Hole C0022A, LWD resistivity images show that the 85-105.5 mbsf interval is fractured and extends above and below a ca. 1 m thick interval characterized by a low resistivity value at 100-101 mbsf. Structures observed in cores from Hole C0022B confirm LWD data. While gently dipping elsewhere, bedding in the 73-146 mbsf interval is steep, commonly exceeding 30°. This bedding dip increase may be a consequence of fault activity (folding ?). Though the low-resistivity interval at 100-101 mbsf could not be sampled at Hole C0022B (no recovery between 95.5 and 99.5 mbsf), cores immediately from above this interval show three ca. 2 cm thick zones of claystone characterized by a marked planar fabric bearing faint striations raking at about 90°. Preliminary biostratigraphic dating in Hole C0022B indicate age reversals at 80.5, 137.5 and 145.5 mbsf, suggesting reverse offset bringing older strata over younger strata. Drilling at IODP Site C0022 confirms that a branch of the megasplay fault previously cored at Expedition 316 Site C0004 extends upwards and southeastwards. The core zone of this branch lies at about 100 mbsf and is about 1 m thick. The presence of weakly foliated claystone suggests aseismic motion immediately above the core zone. The lack of samples from the core zone prevents to determine whether motion was aseismic or not.

Drill Bit Noise Illuminates the San Andreas Fault

NASA Astrophysics Data System (ADS)

Vasconcelos, Ivan; Snieder, Roel; Sava, Paul; Taylor, Tom; Malin, Peter; Chavarria, Andres

2008-09-01

Extracting the vibration response of the subsurface from noise is a rapidly growing field of research [Curtis et al., 2006; Larose et al., 2006]. We carried out broadside imaging of the San Andreas fault zone (SAFZ) using drill bit noise created in the main hole of the San Andreas Fault Observatory at Depth (SAFOD), near Parkfield, Calif. Imaging with drill bit noise is not new, but it traditionally requires the measurement of the vibrations of the drill stem [Rector and Marion, 1991]; such measurements provide the waves radiated by the drill bit. At SAFOD, these measurements were not available due to the absence of an accelerometer mounted on the drill stem. For this reason, the new technique of deconvolution interferometry was used [Vasconcelos and Snieder, 2008]. This technique extracts the waves propagating between seismometers from recordings of incoherent noise.

Geologic Carbon Sequestration in a Lightly Explored Basin: the Puget-Willamette Lowland

NASA Astrophysics Data System (ADS)

Jackson, J. S.

2007-12-01

The Puget-Willamette Lowland is located between the Cascade Range and Olympic Mountains-Coast Range. Exploration for oil and gas there commenced in 1890. Over 700 wells subsequently drilled yield one commercial gas discovery. Eocene sediments deposited west of an ancestral Cascade Range include a coal-bearing sequence covering much of the Puget-Willamette Lowland. The terrestrial deposits pass into marine deposits to the west. Syn- depositional normal faulting and strike-slip faulting are evident in several sub-basins. In the southern Lowland, normal faults were modified by episodes of late Eocene and Miocene transpression, which resulted in mild inversion of older normal faults Preserved sediments indicate that local subsidence continued into Miocene- Pliocene time, and was followed in the northern Lowland by extensive Pleistocene glaciation. In the northern Lowland, Holocene faulting is recognized in outcrop and is interpreted on seismic data acquired in Puget Sound. Structures formed by early Miocene or earlier events may have trapped migrating hydrocarbons. Structures formed or modified by Holocene faulting very probably post-date hydrocarbon generation and migration. The region appears to host potential geologic sequestration targets, including coals, sandstones, and vesicular basalt flows. The size and location of potential traps is poorly constrained by present data. Experience in better explored fore arc basins suggests 10 to 30 percent of the basin may be deformed into suitable trapping geometries. Modern seismic data is required to identify potential sequestration traps. More than one well will be required to confirm the presence and size of these traps. The present boom in oil and gas drilling has created a robust environment for seismic and drilling companies, who command unprecedented rates for their services. Only one seismic crew is presently active on the West Coast, and only a few exploration drilling rigs are available. If this environment persists, then sequestration efforts will compete directly with the hydrocarbon industry for these services, leading to higher service company prices as well as delayed schedules. Carbon sequestration policy thus entails financial incentives that allow geologic sequestration projects to compete for exploration services.

Pumpernickel Valley Geothermal Project Thermal Gradient Wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Z. Adam Szybinski

2006-01-01

The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined withmore » geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for the hot spring area only, was presented by GeothermEx Inc. (2004), which projected that power generation capacities for the Pumpernickel Valley site are 10 MW-30yrs minimum (probablility of >90%), and most likely 13 MW-30yrs.« less

Laboratory Permeability and Seismic velocity anisotropy measurements across the Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Faulkner, D.; Allen, M. J.; Tatham, D.; Mariani, E.; Boulton, C. J.

2015-12-01

The Alpine Fault, a transpressional plate boundary between the Australia-Pacific plates, is known to rupture periodically (200-400yr) with large magnitude earthquakes (Mw~8) and is currently nearing the end of its latest interseismic period. The hydraulic and elastic properties of fault zones influence the nature and style of earthquake rupture and associated processes; investigating these properties in Alpine Fault rocks yields insights into conditions late in the seismic cycle. We present a suite of laboratory permeability and P (Vp) and S (Vs) wave velocity measurements preformed on diverse fault rock lithologies recovered during the first phase of the Deep Fault Drilling Project (DFDP-1). DFDP-1 drilled two boreholes reaching depths of 100.6m and 151.4m and retrieved fault rocks from both the hanging wall and footwall, including ultramylonites, ultracomminuted gouges and variably foliated and unfoliated cataclasites. Drilling revealed a typical shallow fault structure: localised principal slip zones (PSZ) of gouge nested within a damage zone overprinted by a zone of alteration, a record of enhanced fluid-rock interaction. Core material was tested in three orthogonal directions, orientated relative to the down core axis and, when present, foliation. Measurements were conducted with pore pressure held at 5MPa over an effective pressure (Peff) range of 5-105MPa, equivalent to pressure conditions down to ~7km depth. Using the Pulse Transient technique permeabilities at Peff=5MPa range from 10-17 to 10-20m2, decreasing to 10-18 to 10-21m2 at Peff=105MPa. Vp and Vs decrease with increased proximity to the PSZ with Vp in the hanging wall spanning 4500-5900m/s, dropping to 3900-4200m/s at the PSZ and then increasing to 4400-5600m/s in the foot wall. Wave velocities and permeability are enhanced parallel to tectonic fabrics e.g. foliation defined by aligned phyllosillicates and quartz- feldspar clasts. These measurements constrain interseismic conditions within the Alpine Fault, a zone of damaged rock pervasively altered with phyllosilicates and carbonates.

Seismic and gravity investigations of the shallow (upper 1 km) hanging wall of the Alpine Fault in the vicinity of the Whataroa River, New Zealand

NASA Astrophysics Data System (ADS)

Kovacs, A.; Gorman, A. R.; Lay, V.; Buske, S.

2013-12-01

Paleoseismic evidence from the vicinity of the plate-bounding Alpine Fault on New Zealand's South Island suggests that earthquakes of magnitude 7.9 occur every 200-400 years, with the last earthquake occurring in AD 1717. No human observations of this event are recorded. Therefore, the Deep Fault Drilling Project 2 (DFDP-2) drill hole, which is planned for 2014 on the hanging wall of the Alpine Fault in the Whataroa Valley, provides a critical opportunity to study the behavior of this transpressive plate boundary late in its seismogenic cycle. New seismic and gravity data collected since 2011 have been analyzed to assist with the positioning of the drill hole in this glacial valley that provides rare low-elevation access to the hanging wall of the Alpine Fault. The WhataDUSIE controlled-source seismic project, led by researchers from the University of Otago (New Zealand), TU Bergakademie Freiberg (Germany) and the University of Alberta (Canada), provided relatively high-resolution coverage (4-8 m geophone spacing, 25-100 m shot spacing) along a 5-km-long profile across the Alpine Fault in the Whataroa Valley. This work has been supplemented by focused hammer-seismic studies and gravity data collection in the valley. The former targets surface layer properties, whereas the latter targets the depth to the base of the glacially carved paleovalley. In positioning DFDP-2, an understanding of the nature of overburden and valley-fill sediments is critical for drilling design. A velocity model has been developed for the valley based on refraction analysis of the WhataDUSIE and hammer-seismic data combined with a ray-theoretical travel-time tomography (RAYINVR) image of the shallow (uppermost 1 km or so) part of the hanging wall of the Alpine Fault. The model shows that the glacial valley, which presumably was last scoured by ice at the Last Glacial Maximum, has been filled with 200-350 m of post-glacial sediments and outwash gravels. The hanging-wall rocks into which the valley was cut are presumed to be mylonitized Alpine Schist. Considering uplift rates of 6-10 mm/a on the hanging wall of the fault and a glacial withdrawal date of 10,000 years before present (i.e., 60-100 m of uplift since the ice vacated the valley), the floor of the valley would have been as deep as about 350 m below sea level at the time that the ice withdrew (given the current elevation of ~100 m on the valley floor). Basal sediments in the valley could therefore be either marine (if the valley was open to the ocean) or lacustrine (if the valley was isolated from the open ocean by elevated footwall rocks along the west coast of the South Island). Once the original water body in the valley was filled, sediments would accumulate as outwash gravels above sea level.

Structural and physical property characterization in the Wenchuan earthquake Fault Scientific Drilling project — hole 1 (WFSD-1)

NASA Astrophysics Data System (ADS)

Li, Haibing; Xu, Zhiqin; Niu, Yixiong; Kong, Guangsheng; Huang, Yao; Wang, Huan; Si, Jialiang; Sun, Zhiming; Pei, Junling; Gong, Zheng; Chevalier, Marie-Luce; Liu, Dongliang

2014-04-01

The Wenchuan earthquake Fault Scientific Drilling project (WFSD) started right after the 2008 Mw 7.9 Wenchuan earthquake to investigate its faulting mechanism. Hole 1 (WFSD-1) reached the Yingxiu-Beichuan fault (YBF), and core samples were recovered from 32 to 1201.15 m-depth. Core investigation and a suite of geophysical downhole logs (including P-wave velocity, natural gamma ray, self-potential, resistivity, density, porosity, temperature, magnetic susceptibility and ultrasound borehole images) were acquired in WFSD-1. Integrated studies of cores and logs facilitate qualitative and quantitative comparison of the structures and physical properties of rocks. Logging data revealed that the geothermal gradient of the volcanic Pengguan complex (above 585.75 m) is 1.85 °C/100 m, while that of the sedimentary Xujiahe Formation (below 585.75 m) is 2.15 °C/100 m. In general, natural gamma ray, resistivity, density, porosity, P-wave velocity and magnetic susceptibility primarily depend on the rock lithology. All major fault zones are characterized by high magnetic susceptibility, low density and high porosity, with mostly low resistivity, high natural gamma ray and sound wave velocity. The high magnetic susceptibility values most likely result from the transformation of magnetic minerals by frictional heating due to the earthquake. The YBF exposed in WFSD-1 can be subdivided into five different parts based on different logging responses, each of them corresponding to certain fault-rocks. The high gamma radiation, porosity and P-wave velocity, as well as low resistivity and temperature anomalies indicate that the Wenchuan earthquake fault zone is located at 585.75-594.5 m-depth, with an average inclination and dip angle of N305° and 71°, respectively. The fact that the fracture directions in the hanging wall and footwall are different suggests that their stress field direction is completely different, implying that the upper Pengguan complex may not be local.

Development of Hydrologic Characterization Technology of Fault Zones -- Phase I, 2nd Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karasaki, Kenzi; Onishi, Tiemi; Black, Bill

2009-03-31

This is the year-end report of the 2nd year of the NUMO-LBNL collaborative project: Development of Hydrologic Characterization Technology of Fault Zones under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix 3. Literature survey of published information on the relationship between geologic and hydrologic characteristics of faults was conducted. The survey concluded that it may be possible to classify faults by indicators based on various geometric and geologic attributes that may indirectly relate to the hydrologic property of faults. Analysis of existing information on the Wildcat Fault and its surrounding geology was performed. Themore » Wildcat Fault is thought to be a strike-slip fault with a thrust component that runs along the eastern boundary of the Lawrence Berkeley National Laboratory. It is believed to be part of the Hayward Fault system but is considered inactive. Three trenches were excavated at carefully selected locations mainly based on the information from the past investigative work inside the LBNL property. At least one fault was encountered in all three trenches. Detailed trench mapping was conducted by CRIEPI (Central Research Institute for Electric Power Industries) and LBNL scientists. Some intriguing and puzzling discoveries were made that may contradict with the published work in the past. Predictions are made regarding the hydrologic property of the Wildcat Fault based on the analysis of fault structure. Preliminary conceptual models of the Wildcat Fault were proposed. The Wildcat Fault appears to have multiple splays and some low angled faults may be part of the flower structure. In parallel, surface geophysical investigations were conducted using electrical resistivity survey and seismic reflection profiling along three lines on the north and south of the LBNL site. Because of the steep terrain, it was difficult to find optimum locations for survey lines as it is desirable for them to be as straight as possible. One interpretation suggests that the Wildcat Fault is westerly dipping. This could imply that the Wildcat Fault may merge with the Hayward Fault at depth. However, due to the complex geology of the Berkeley Hills, multiple interpretations of the geophysical surveys are possible. iv An effort to construct a 3D GIS model is under way. The model will be used not so much for visualization of the existing data because only surface data are available thus far, but to conduct investigation of possible abutment relations of the buried formations offset by the fault. A 3D model would be useful to conduct 'what if' scenario testing to aid the selection of borehole drilling locations and configurations. Based on the information available thus far, a preliminary plan for borehole drilling is outlined. The basic strategy is to first drill boreholes on both sides of the fault without penetrating it. Borehole tests will be conducted in these boreholes to estimate the property of the fault. Possibly a slanted borehole will be drilled later to intersect the fault to confirm the findings from the boreholes that do not intersect the fault. Finally, the lessons learned from conducting the trenching and geophysical surveys are listed. It is believed that these lessons will be invaluable information for NUMO when it conducts preliminary investigations at yet-to-be selected candidate sites in Japan.« less

Structure and composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake.

PubMed

Chester, Frederick M; Rowe, Christie; Ujiie, Kohtaro; Kirkpatrick, James; Regalla, Christine; Remitti, Francesca; Moore, J Casey; Toy, Virginia; Wolfson-Schwehr, Monica; Bose, Santanu; Kameda, Jun; Mori, James J; Brodsky, Emily E; Eguchi, Nobuhisa; Toczko, Sean

2013-12-06

The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.

San Andreas drilling sites selected

NASA Astrophysics Data System (ADS)

Ellsworth, Bill; Zoback, Mark

A new initiative for drilling and coring directly into the San Andreas fault at depths up to 10 km is being proposed by an international team of scientists led by Mark Zoback, Stanford University; Steve Hickman and Bill Ellsworth, U.S. Geological Survey; and Lee Younker, Lawrence Livermore Laboratory. In addition to exhuming samples of fault rock and fluids from seismogenic depths, the hole will be used to make a wide range of geophysical measurements within the fault zone and to monitor the fault zone over time. Four areas along the San Andreas have been selected as candidates for deep drilling: the Mojave segment of the San Andreas between Leona Valley and Big Pine, the Carrizo Plain, the San Francisco Peninsula between Los Altos and Daly City, and the Northern Gabilan Range between the Cienga winery and Melendy Ranch. These sites were chosen from an initial list compiled at the International Fault Zone Drilling Workshop held in Asilomar, Calif., in December 1992 and at meetings held this winter and spring in Menlo Park, Calif.

Structure of the San Andreas fault zone at SAFOD from a seismic refraction survey

USGS Publications Warehouse

Hole, J.A.; Ryberg, T.; Fuis, G.S.; Bleibinhaus, F.; Sharma, A.K.

2006-01-01

Refraction traveltimes from a 46-km long seismic survey across the San Andreas Fault were inverted to obtain two-dimensional velocity structure of the upper crust near the SAFOD drilling project. The model contains strong vertical and lateral velocity variations from <2 km/s to ???6 km/s. The Salinian terrane west of the San Andreas Fault has much higher velocity than the Franciscan terrane east of the fault. Salinian basement deepens from 0.8 km subsurface at SAFOD to ???2.5 km subsurface 20 km to the southwest. A strong reflection and subtle velocity contrast suggest a steeply dipping fault separating the Franciscan terrane from the Great Valley Sequence. A low-velocity wedge of Cenozoic sedimentary rocks lies immediately southwest of the San Andreas Fault. This body is bounded by a steep fault just northeast of SAFOD and approaches the depth of the shallowest earthquakes. Multiple active and inactive fault strands complicate structure near SAFOD. Copyright 2006 by the American Geophysical Union.

Central Japan's Atera Active Fault's Wide-Fractured Zone: An Examination of the Structure and In-situ Crustal Stress

NASA Astrophysics Data System (ADS)

Ikeda, R.; Omura, K.; Matsuda, T.; Mizuochi, Y.; Uehara, D.; Chiba, A.; Kikuchi, A.; Yamamoto, T.

2001-12-01

In-situ downhole measurements and coring within and around an active fault zone are needed to better understand the structure and material properties of fault rocks as well as the physical state of active faults and intra-plate crust. Particularly, the relationship between the stress concentration state and the heterogeneous strength of an earthquake fault zone is important to estimate earthquake occurrence mechanisms which correspond to the prediction of an earthquake. It is necessary to compare some active faults in different conditions of the chrysalis stage and their relation to subsequent earthquake occurrence. To better understand such conditions, "Active Fault Zone Drilling Project" has been conducted in the central part of Japan by the National Research Institute for Earth Science and Disaster Prevention. The Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2) and the Neodani fault created by the 1981 Nobi earthquake, the greatest inland earthquake M=8.0 in Japan, have been drilled through the fault fracture zones. During these past four years, a similar experiment and research at the Atera fault, of which some parts seem to have been dislocated by the 1586 Tensyo earthquake, has been undertaken. The features of the Atera fault are as follows: (1) total length is about 70 km, (2) general trend is NW45_Kwith a left-lateral strike slip, (3) slip rate is estimated as 3-5 m/1000 yrs. and the average recurrence time as 1700 yrs., (4) seismicity is very low at present, and (5) lithologies around the fault are basically granitic rocks and rhyolite. We have conducted integrated investigations by surface geophysical survey and drilling around the Atera fault. Six boreholes have been drilled from the depth of 400 m to 630 m. Four of these boreholes are located on a line crossing the fracture zone of the Atera fault. Resistivity and gravity structures inferred from surface geophysical surveys were compared with the physical properties determined from the borehole logging data and core samples. These results were also compared with in situ stress data by the hydraulic fracturing stress measurements in the boreholes. We obtained characteristic states on crustal stress and strength of the fault from these investigations. Our findings are as follows: (1) The fracture zone around the Atera fault shows a very wide and complex fracture structure, from approximately 1 km to 4 km wide. The average slip rate was estimated to be 5.3 m /1000 yrs. by the distribution of basalt in age of 1.5 Ma by radioactive dating. We inferred that the Atera fault has been repeatedly active in recent geologic time; however, it is in a very weak state at present. (2) The stress magnitude decreases in the area closer to the center of the fracture zone. Furthermore the orientation of the maximum horizontal compressive stress was almost in a North-South direction, just reverse of the fault moving direction. These are important results to evaluate fault activity. We argue that the stress state observed in these sites exists only when the faults are quite "weak," and thus does not reach to a critical level of fault activation in the present situation.

Structure, Frictional Melting and Fault Weakening during the 2008 Mw 7.9 Wenchuan Earthquake Slip: Observation from the WFSD Drilling Core Samples

NASA Astrophysics Data System (ADS)

Li, H.; Wang, H.; Li, C.; Zhang, J.; Sun, Z.; Si, J.; Liu, D.; Chevalier, M. L.; Han, L.; Yun, K.; Zheng, Y.

2015-12-01

The 2008 Mw7.9 Wenchuan earthquake produced two co-seismic surface ruptures along Yingxiu-Beichuan fault (~270 km) and the Guanxian-Anxian fault (~80 km) simultaneously in the Longmen Shan thrust belt. Besides, two surface rupture zones were tracked in the southern segment of the Yingxiu-Beichuan rupture zone, one along the Yingxiu fault, the other along the Shenxigou-Longchi fault, which both converged into one rupture zone at the Bajiaomiao village, Hongkou town, where one distinct fault plane with two striation orientations was exposed. The Wenchuan earthquake Fault Scientific Drilling project (WFSD) was carried out right after the earthquake to investigate its faulting mechanisms and rupture process. Six boreholes were drilled along the rupture zones with depths ranging from 600 to 2400 m. WFSD-1 and WFSD-2 are located at the Bajiaomiao area, the southern segment of the Yingxiu-Beichuan rupture zone, while WFSD-4 and WFSD-4S are in the Nanba town area, in the northern part of the rupture zone. Detailed research showed that ~1 mm thick Principal Slip Zone (PSZ) of the Wenchuan earthquake is located at ~589 m-depth in the WFSD-1 cores. Graphite present in the PSZ indicates a low fault strength. Long-term temperature monitoring shows an extremely low fault friction coefficient during the earthquake. Recently, another possible PSZ was found in WFSD-1 cores at ~732 m-depth, with a ~2 mm thick melt layer in the fault gouge, where feldspar was melted but quartz was not, indicating that the frictional melting temperature was 1230°C < T < 1720°C. These two PSZs at depth may correspond to the two co-seismic surface rupture zones. Besides, the Wenchuan earthquake PSZ was also recognized in the WFSD-4S cores, at ~1084 m-depth. About 200-400 μm thick melt layer (fault vein, mainly feldspar), as well as melt injection veins, were observed in the slip zone, where oblique distinct striations were visible on the slip surface. Therefore, there are two PSZs in the shallow crust at the southern segment along the Yingxiu-Beichuan fault, and another one along the northern segment. Melt and graphite in the PSZs indicate that the frictional melting and thermal pressurization are the main fault mechanisms during the Wenchuan earthquake. The melt and graphite can be considered as markers of large earthquakes.

Finding Faults: Tohoku and other Active Megathrusts/Megasplays

NASA Astrophysics Data System (ADS)

Moore, J. C.; Conin, M.; Cook, B. J.; Kirkpatrick, J. D.; Remitti, F.; Chester, F.; Nakamura, Y.; Lin, W.; Saito, S.; Scientific Team, E.

2012-12-01

Current subduction-fault drilling procedure is to drill a logging hole, identify target faults, then core and instrument them. Seismic data may constrain faults but the additional resolution of borehole logs is necessary for efficient coring and instrumentation under difficult conditions and tight schedules. Thus, refining the methodology of identifying faults in logging data has become important, and thus comparison of log signatures of faults in different locations is worthwhile. At the C0019 (JFAST) drill site, the Tohoku megathrust was principally identified as a decollement where steep cylindrically-folded bedding abruptly flattens below the basal detachment. A similar structural contrast occurs across a megasplay fault in the NanTroSEIZE transect (Site C0004). At the Tohoku decollement, a high gamma-ray value from a pelagic clay layer, predicted as a likely decollement sediment type, strengthens the megathrust interpretation. The original identification of the pelagic clay as a decollement candidate was based on results of previous coring of an oceanic reference site. Negative density anomalies, often seen as low resistivity zones, identified a subsidiary fault in the deformed prism overlying the Tohoku megathrust. Elsewhere, at Barbados, Nankai (Moroto), and Costa Rica, negative density anomalies are associated with the decollement and other faults in hanging walls. Log-based density anomalies in fault zones provide a basis for recognizing in-situ fault zone dilation. At the Tohoku Site C0019, breakouts are present above but not below the megathrust. Changes in breakout orientation and width (stress magnitude) occur across megasplay faults at Sites C0004 and C0010 in the NantroSEIZE transect. Annular pressure anomalies are not apparent at the Tohoku megathrust, but are variably associated with faults and fracture zones drilled along the NanTroSEIZE transect. Overall, images of changes in structural features, negative density anomalies, and changes in breakout occurrence and orientation provide the most common log criteria for recognizing major thrust zones in ocean drilling holes at convergent margins. In the case of JFAST, identification of faults by logging was confirmed during subsequent coring activities, and logging data was critical for successful placement of the observatory down hole.

Frictional properties of fault rocks along the shallow part of the Japan Trench décollement: insights from samples recovered during the Integrated Ocean Drilling Project Expedition 343 (the JFAST project)

NASA Astrophysics Data System (ADS)

Remitti, Francesca; Smith, Steven; Gualtieri, Alessandro; Di Toro, Giulio; Nielsen, Stefan

2014-05-01

The Japan Trench Fast Drilling Project (JFAST), Integrated Ocean Drilling Program (IODP) Expedition 343, successfully located and sampled the shallow slip zone of the Mw =9.0 Tohoku-Oki earthquake where the largest coseismic slip occurred (c. 50 m). Logging-while-drilling, core-sample observations and the analysis of temperature data recovered from a third borehole show that a thin (<5 m), smectite rich plate-boundary fault accommodated the large slip of the Tohoku-Oki Earthquake rupture, as well as most of the interplate motion at the drill site. Effective normal stress along the shallow plate-boundary fault is estimated to be c. 7 MPa. Single-velocity and velocity-stepping rotary-shear friction experiments on fault material were performed with the Slow to HIgh Velocity Apparatus (SHIVA) installed at INGV in Rome. Quantitative phase analysis using the combined Rietveld and R.I.R. method indicates that the starting material is mainly composed of smectite (56 wt%) and illite/mica (21 wt%) and minor quartz, kaolinite, plagioclase and K-feldspar. The amount of amorphous fraction has also been calculated and it is close to the detection limit. Each experiment used 3.5 g of loosely disaggregated gouge, following sieving to a particle size fraction <1 mm. Experiments were performed either 1) "room-dry" (40-60% humidity) at 8.5 MPa normal stress (one test at 12.5 MPa), or 2) "water-dampened" (0.5 ml distilled water added to the gouge layers) at 3.5 MPa normal stress. Slip velocities ranged over nearly seven orders of magnitude (10-5 - 3 m s-1). Total displacement is always less than 1 m. The peak and steady-state frictional strengths of the gouges are significantly lower under water-dampened conditions, with mean steady-state friction coefficients (μ, shear stress/normal stress) at all investigated velocities of 0.04<μ<0.1. This is consistent with the small measured frictional heat anomaly along the plate boundary fault ~1.5 years after the Tohoku-Oki earthquake. Under room-dry conditions the gouge material is velocity-strengthening at intermediate velocities (0.001 - 0.1 m s-1), but strongly velocity-weakening at > 0.1 m s-1. Instead, under water-dampened conditions, the gouge is velocity-neutral to velocity-weakening at all investigated velocities. In other words, the intermediate-velocity strengthening, which would probably act as a "barrier" to rupture propagation in the dry gouges, disappears in water-dampened gouges. This result is compatible with propagation of the Tohoku rupture to the trench, and also with large coseismic slip at shallow depths. Quantitative phase analysis using the combined Rietveld and R.I.R. method has been performed also on six post-experiment gouges for the determination of both the crystalline and amorphous fractions. Preliminary results show that the mineralogical assemblage is basically the same after the experiments, with both smectite and illite phases preserved, this suggests that the weakening mechanism operating in this material is active at low temperature.

New insights into seismic faulting during the 2008 Mw7.9 Wenchuan earthquake

NASA Astrophysics Data System (ADS)

Li, H.; Wang, H.; Si, J.; Sun, Z.; Pei, J.; Lei, Z.; He, X.

2017-12-01

The WFSD project was implemented promptly after the 2008 Mw 7.9 Wenchuan earthquake. A series of research results on the seismogenic structure, fault deformation, sliding mechanism and fault healing have been obtained, which provide new insights into seismic faulting and mechanisms of the Wenchuan earthquake. The WFSD-1 and -2 drilling core profiles reveal that the Longmen Shan thrust belt is composed of multiple thrust sheets. The 2008 Wenchuan earthquake took place in such tectonic setting with strong horizontal shortening. The two ruptured faults have different deformation mechanisms. The Yingxiu-Beichuan fault (YBF) is a stick-slip fault characterized by fault gouge with high magnetic susceptibility, Guanxian-Anxian fault (GAF) with creeping features and characterized by fault gouge with low magnetic susceptibility. Two PSZs were found in WFSD-1 and -2 cores in the southern segment of YBF. The upper PSZ1 is a low-angle thrust fault characterized by coseisimc graphitization with an extremely low frictional coefficient. The lower PSZ2 is an oblique dextral-slip thrust fault characterized by frictional melt lubrication. In the northern segment of YBF, the PSZ in WFSD-4S cores shows a high-angle thrust feature with fresh melt as well. Therefore, the oblique dextral-slip thrust faulting with frictional melt lubrication is the main faulting of Wenchuan earthquake. Fresh melt with quenching texture was formed in Wenchuan earthquake implying vigorous fluid circulation occurred during the earthquake, which quenched high-temperature melt, hamper the aftermost fault slip and welding seismic fault. Therefore, fluids in the fault zone not only promotes fault weakening, but also suppress slipping in theWenchuan earthquake. The YBF has an extremely high hydraulic diffusivity (2.4×10-2 m2s-1), implying a vigorous fluid circulation in the Wenchuan fault zone. the permeability of YBF has reduced 70% after the shock, reflecting a rapid healing for the YBF. However, the water level has not changed in the WFSD-3 borehole drilled through GAF, indicating an unchanged permeability. These results are of great significance to understanding the seismogenic mechanisms and earthquake cycle for the Wenchuan earthquake.

High-velocity frictional properties of Alpine Fault rocks: Mechanical data, microstructural analysis, and implications for rupture propagation

NASA Astrophysics Data System (ADS)

Boulton, Carolyn; Yao, Lu; Faulkner, Daniel R.; Townend, John; Toy, Virginia G.; Sutherland, Rupert; Ma, Shengli; Shimamoto, Toshihiko

2017-04-01

The Alpine Fault in New Zealand is a major plate-bounding structure that typically slips in ∼M8 earthquakes every c. 330 years. To investigate the near-surface, high-velocity frictional behavior of surface- and borehole-derived Alpine Fault gouges and cataclasites, twenty-one rotary shear experiments were conducted at 1 MPa normal stress and 1 m/s equivalent slip velocity under both room-dry and water-saturated (wet) conditions. In the room-dry experiments, the peak friction coefficient (μp = τp/σn) of Alpine Fault cataclasites and fault gouges was consistently high (mean μp = 0.67 ± 0.07). In the wet experiments, the fault gouge peak friction coefficients were lower (mean μp = 0.20 ± 0.12) than the cataclasite peak friction coefficients (mean μp = 0.64 ± 0.04). All fault rocks exhibited very low steady-state friction coefficients (μss) (room-dry experiments mean μss = 0.16 ± 0.05; wet experiments mean μss = 0.09 ± 0.04). Of all the experiments performed, six experiments conducted on wet smectite-bearing principal slip zone (PSZ) fault gouges yielded the lowest peak friction coefficients (μp = 0.10-0.20), the lowest steady-state friction coefficients (μss = 0.03-0.09), and, commonly, the lowest specific fracture energy values (EG = 0.01-0.69 MJ/m2). Microstructures produced during room-dry and wet experiments on a smectite-bearing PSZ fault gouge were compared with microstructures in the same material recovered from the Deep Fault Drilling Project (DFDP-1) drill cores. The near-absence of localized shear bands with a strong crystallographic preferred orientation in the natural samples most resembles microstructures formed during wet experiments. Mechanical data and microstructural observations suggest that Alpine Fault ruptures propagate preferentially through water-saturated smectite-bearing fault gouges that exhibit low peak and steady-state friction coefficients.

Origin and nature of crystal reflections: Results from integrated seismic measurements at the KTB superdeep drilling site

NASA Astrophysics Data System (ADS)

Harjes, H.-P.; Bram, K.; Dürbaum, H.-J.; Gebrande, H.; Hirschmann, G.; Janik, M.; KlöCkner, M.; Lüschen, E.; Rabbel, W.; Simon, M.; Thomas, R.; Tormann, J.; Wenzel, F.

1997-08-01

For almost 10 years the KTB superdeep drilling project has offered an excellent field laboratory for adapting seismic techniques to crystalline environments and for testing new ideas for interpreting seismic reflections in terms of lithological or textural properties of metamorphic rock units. The seismic investigations culminated in a three-dimensional (3-D) reflection survey on a 19×19 km area with the drill site at its center. Interpretation of these data resulted in a detailed, structural model of the German Continental Deep Drilling Program (KTB) location with dominant, steep faults in the upper crust. The 3-D reflection survey was part of a suite of seismic experiments, ranging from wide-angle reflection and refraction profiles to standard vertical seismic profiles (VSP) and more sophisticated surface-to-borehole observations. It was predicted that the drill bit would meet the most prominent, steeply dipping, crustal reflector at a depth of about 6500-7000 m, and indeed, the borehole penetrated a major fault zone in the depth interval between 6850 and 7300 m. This reflector offered the rare opportunity to relate logging results, reflective properties, and geology to observed and modeled data. Post-Variscan thrusting caused cataclastic deformation, with partial, strong alterations within a steeply dipping reverse fault zone. This process generated impedance contrasts within the fault zone on a lateral scale large enough to cause seismic reflections. This was confirmed by borehole measurements along the whole 9.1 km deep KTB profile. The strongest, reflected signals originated from fluid-filled fractures and cataclastic fracture zones rather than from lithological boundaries (i.e., first-order discontinuities between different rock types) or from texture- and/or foliation-induced anisotropy. During the interpretation of seismic data at KTB several lessons were learned: Conventional processing of two-dimensional (2-D) reflection data from a presite survey showed predominantly subhorizontal layering in the upper crust with reflectivity striking in the Variscan direction. Drilling, however, revealed that all rock units are steeply dipping. This confirms that surface common depth point (CDP) seismics strongly enhances subhorizontal reflectivity and may thus produce a very misleading crustal image. Although this was shown for synthetic examples earlier, the KTB provides the experimental proof of how crucial this insight can be.

Proposed Drill Sites

DOE Data Explorer

Lane, Michael

2013-06-28

Proposed drill sites for intermediate depth temperature gradient holes and/or deep resource confirmation wells. Temperature gradient contours based on shallow TG program and faults interpreted from seismic reflection survey are shown, as are two faults interpreted by seismic contractor Optim but not by Oski Energy, LLC.

Monroe, Utah, Hydrothermal System: Results from Drilling of Test Wells MC1 and MC2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, D.S.; Harrison, Roger

1978-10-01

Following detailed geological (Parry et al., 1976; Miller, 1976) and geophysical (Mase, Chapman, and Ward, 1978; Kilty, Mase, and Chapman, 1978) studies of the Monroe, Utah hydrothermal system, a program of drilling two intermediate depth test wells was undertaken. The objectives of the test well drilling were three-fold: (1) to obtain structural information bearing on the poorly known dip of the Sevier Fault, (2) to obtain temperature information below the shallow depths (approximately 300 ft.) sampled in the first phase of exploration, and (3) to provide cased wells which could act as monitor wells during the production phase of themore » project. The test well drilling was seen to be vital to the selection of a site for a production well. This report describes the results from the drilling of the two test wells, designated MC1 and MC2, and offers interpretation of the hydrothermal system which may be used as a basis for selecting production wells.« less

Structure and clay mineralogy: borehole images, log interpretation and sample analyses at Site C0002 Nankai Trough accretionary prism

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Schleicher, Anja

2015-04-01

Our research focused on the characterization of fracture and fault structures from the deep Nankai Trough accretionary prism in Japan. Logging Data and cuttings samples from the two most recent International Ocean Discovery Program (IODP) Expeditions 338 and 348 of the NanTroSEIZE project were analyzed by Logging While Drilling (LWD) oriented images, geophysical logs and clay mineralogy. Both expeditions took place at Site C0002, but whereas Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002N and C0002P (Expedition 348) reached a depth of 2325.5 mbsf and 3058.8 mbsf respectively. The structural interpretation of borehole imaging data illustrates the deformation within the fractured and faulted sections of the accretionary prism. All drill holes show distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Here, smectite and illite are the most common clay minerals, but the properties and the role they may play in influencing the fractures, faults and folds in the accretionary prism is still not well understood. When comparing clay mineralogy and fracture/fault areas in hole C0002F (Expedition 338), a trend in the abundance of illite and smectite, and in particular the swelling behavior of smectite is recognizable. In general, the log data provided a good correlation with the actual mineralogy and the relative abundance of clay. Ongoing postcruise preliminary research on hole C0002 N and C0002P (Expedition 348) should confirm these results. The relationship between fracture and fault structures and the changes in clay mineralogy could be explained by the deformation of specific areas with different compaction features, fluid-rock interaction processes, but could also be related to beginning diagenetic processes related to depth. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the Nankai accretionary prism. This is critical for our understanding of clay-fluid interaction and mechanical properties duing fault displacements and seismogenesis.

Merging high resolution geophysical and geochemical surveys to reduce exploration risk at glass buttes, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walsh, Patrick; Fercho, Steven; Perkin, Doug

2015-06-01

The engineering and studies phase of the Glass Buttes project was aimed at reducing risk during the early stages of geothermal project development. The project’s inclusion of high resolution geophysical and geochemical surveys allowed Ormat to evaluate the value of these surveys both independently and in combination to quantify the most valuable course of action for exploration in an area where structure, permeability, and temperature are the most pressing questions. The sizes of the thermal anomalies at Glass Buttes are unusually large. Over the course of Phase I Ormat acquired high resolution LIDAR data to accurately map fault manifestations atmore » the surface and collected detailed gravity and aeromagnetic surveys to map subsurface structural features. In addition, Ormat collected airborne hyperspectral data to assist with mapping the rock petrology and mineral alteration assemblages along Glass Buttes faults and magnetotelluric (MT) survey to try to better constrain the structures at depth. Direct and indirect identification of alteration assemblages reveal not only the geochemical character and temperature of the causative hydrothermal fluids but can also constrain areas of upflow along specific fault segments. All five datasets were merged along with subsurface lithologies and temperatures to predict the most likely locations for high permeability and hot fluids. The Glass Buttes temperature anomalies include 2 areas, totaling 60 km2 (23 mi2) of measured temperature gradients over 165° C/km (10° F/100ft). The Midnight Point temperature anomaly includes the Strat-1 well with 90°C (194 °F) at 603 m (1981 ft) with a 164 °C/km (10°F/100ft) temperature gradient at bottom hole and the GB-18 well with 71°C (160 °F) at 396 m (1300 ft) with a 182°C/km (11°F/100ft) gradient. The primary area of alteration and elevated temperature occurs near major fault intersections associated with Brothers Fault Zone and Basin and Range systems. Evidence for faulting is observed in each data set as follows. Field observations include fault plane orientations, complicated fault intersections, and hydrothermal alteration apparently pre-dating basalt flows. Geophysical anomalies include large, linear gradients in gravity and aeromagnetic data with magnetic lows possibly associated with alteration. Resistivity low anomalies also appear to have offsets associated with faulting. Hyperspectral and XRF identified alteration and individual volcanic flow units, respectively. When incorporated into a 3D geologic model, the fault intersections near the highest proven temperature and geophysical anomalies provide the first priority targets at Midnight Point. Ormat geologists selected the Midnight Point 52-33 drilling target based on a combination of pre-existing drilling data, geologic field work, geophysical interpretation, and geochemical analysis. Deep temperatures of well 52-33 was lower than anticipated. Temperature gradients in the well mirrored those found in historical drilling, but they decreased below 1500 ft and were isothermal below 2000 ft.« less

A Reference Section through the Lower Fast-spreading Oceanic Crust in the Wadi Gideah (Sumail ophiolite, Sultanate Oman): Drill Sites GT1A and GT2A within the ICDP Oman Drilling Project

NASA Astrophysics Data System (ADS)

Mueller, S.; Koepke, J.; Garbe-Schoenberg, C. D.; Müller, T.; Mock, D.; Strauss, H.; Schuth, S.; Ildefonse, B.

2017-12-01

In the absence of a complete profile through fast-spreading oceanic crust in modern oceans, we established a reference profile through the whole paleocrust of the Sumail Ophiolite (Oman), which is regarded as the best analogue for fast-spreading oceanic crust on land. For establishing a coherent data set, we sampled the Wadi Gideah in the Wadi-Tayin massif from the mantle section up to the pillow basalts and performed different analytical and structural investigations on the same suite of samples (pool sample concept). The whole sample set contains about 400 samples focusing on both primary magmatic rocks and hydrothermal fault zones to characterize initial formation processes and cooling of the crust. The Wadi Gideah hosts the sites GT1A (lower crust) and GT2A (foliated / layered gabbro transition) where 400 m long cores have been drilled in the frame of the ICDP Oman Drilling Project (OmanDP). Thus, the Wadi Gideah crustal transect is well-suited for providing a reference frame for these two drill cores. Major and trace element data on minerals and rocks reveal in-situ crystallization in the deep crust, thus strongly supporting a hybrid accretion model that is characterized by sheeted sill intrusion in the lower part of the plutonic crust and gabbro glacier features in the upper section. This hybrid model is also supported by results on crystallographic preferred orientations (CPO) of the minerals within the gabbros, which call for distinct formation mechanisms in the upper and lower gabbro sections. A requirement for our hybrid model is significant hydrothermal cooling in the lower crust for the consumption of the latent heat of crystallization. This was facilitated by channelled hydrothermal flow zones, preserved today in faulted zones of extensively altered gabbro cutting both layered and foliated gabbros. These gabbros show higher Sr87/Sr86 ratios if compared to the background gabbro, the presence of late stage minerals (amphibole, oxides, orthopyroxene, apatite) and evidence for hydrous partial melting, as consequence of fluid / rock interaction at very high temperatures. Obviously, these fault zones remained active for channelled fluid flow during the entire cooling stage of the oceanic crust down to low-temperature mineral assemblages.

Fracture zone drilling through Atotsugawa fault in central Japan - geological and geophysical structure -

NASA Astrophysics Data System (ADS)

Omura, K.; Yamashita, F.; Yamada, R.; Matsuda, T.; Fukuyama, E.; Kubo, A.; Takai, K.; Ikeda, R.; Mizuochi, Y.

2004-12-01

Drilling is an effective method to investigate the structure and physical state in and around the active fault zone, such as, stress and strength distribution, geological structure and materials properties. In particular, the structure in the fault zone is important to understand where and how the stress accumulates during the earthquake cycle. In previous studies, we did integrate investigation on active faults in central Japan by drilling and geophysical prospecting. Those faults are estimated to be at different stage in the earthquake cycle, i.e., Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2), the Neodani fault which appeared by the 1891 Nobi earth-quake (M=8.0), the Atera fault, of which some parts have seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9), and Gofukuji Fault that is considered to have activated about 1200 years ago. Each faults showed characteristic features of fracture zone structure according to their geological and geophysical situations. In a present study, we did core recovery and down hole measurements at the Atotsugawa fault, central Japan, that is considered to have activated at 1858 Hida earthquake (M=7.0). The Atotsugawa fault is characterized by active seismicity along the fault. But, at the same time, the shallow region in the central segment of the fault seems to have low seismicity. The high seismicity segment and low seismicity segments may have different mechanical, physical and material properties. A 350m depth borehole was drilled vertically beside the surface trace of the fault in the low seismicity segment. Recovered cores were overall heavily fractured and altered rocks. In the cores, we observed many shear planes holding fault gouge. Logging data showed that the apparent resistance was about 100 - 600 ohm-m, density was about 2.0 - 2.5g/cm3, P wave velocity was approximately 3.0 - 4.0 km/sec, neutron porosity was 20 - 40 %. Results of physical logging show features of fault fracture zone that were the same as the fault fracture zones of other active faults that we have drilled previously. By the BHTV logging, we detected many fractures of which the strikes are not only parallel to the fault trace bur also oblique to the fault trace. The observations of cores and logging data indicate that the borehole passed in the fracture zone down to the bottom, and that the fracture zone has complicate internal structure including foliation not parallel to the fault trace. The core samples are significant for further investigation on material properties in the fracture zone. And we need data of geophysical prospecting to infer the deeper structure of the fracture zone.

Do mesoscale faults near the tip of an active strike-slip fault indicate regional or local stress?

NASA Astrophysics Data System (ADS)

Yamaji, Atsushi

2017-04-01

Fault-slip analysis is used in Japan after the Great Tohoku Earthquake (2011) to judge the stability of fractures in the foundations of nuclear power plants. In case a fault-slip datum from a fracture surface is explained by the present stress condition, the fracture is thought to have a risk to be activated as a fault. So, it is important to understand the relative significance of regional and local stresses. To answer the question whether mesoscale faults indicate regional or local stress, fault-slip data were collected from the walls of a trenching site of the Nojima Fault in central Japan—an active, dextral, strike-slip fault. The fault gave rise to the 1995 Kobe earthquake, which killed more than 6000 people. The trench was placed near the fault tip, which produced compressional and extensional local stress conditions on the sides of the fault near the tip. A segment of the fault, which ruptured the surface in 1995, bounded Cretaceous granite and latest Pliocene sediments in the trench. As a result, the stress inversion of the data from the mesoscale faults observed in the trench showed both the local stresses. The present WNW-ESE regional compression was found from the compressive side, but was not in the extensional side, probably because local extension surpassed the regional compression. Instead, the regional N-S compression of the Early Pleistocene was found from the extensional side. From this project, we got the lesson that fault-slip analysis reveals regional and local stresses, and that local stress sometimes masks regional one. This work was supported by a science project of "Drilling into Fault Damage Zone" (awarded to A. Lin) of the Secretariat of Nuclear Regulation Authority (Japan).

Answers from deep inside the Earth; Continental Scientific Drilling at Cajon Pass, California

USGS Publications Warehouse

Russ, D.P.

1989-01-01

Drilling of a 12,000-foot-deep scientific well has been completed at Cajon Pass in southern California to measure crustal properties, to determine crustal structure, and to better understanding the generation of earthquakes along the San Andreas fault. A joint effort of the National Science Foundation (NFS) and the U.S Geological Survey (USGS), the well was begun in November 1986, and is one of the first projects to be undertaken in the new national Continental Scientific Drilling Program. This program aims to enchance our knowledge of the compostiion, sturcture, dynamics, and evolution of the continental crust and of how these factors affect the origin and distribution of mineral and energy resources and natural phenomena such as volcanic eruptions and earthquakes. 

High-velocity frictional strength across the Tohoku-Oki megathrust determined from surface drilling torque

NASA Astrophysics Data System (ADS)

Ujiie, K.; Inoue, T.; Ishiwata, J.

2015-12-01

Frictional strength at seismic slip rates is a key to evaluate fault weakening and rupture propagation during earthquakes. The Japan Trench First Drilling Project (JFAST) drilled through the shallow plate-boundary thrust, where huge displacements of ~50 m occurred during the 2011 Tohoku-Oki earthquake. To determine the downhole frictional strength at drilled site (Site C0019), we analyzed surface drilling data. The equivalent slip rate estimated from the rotation rate and inner and outer radiuses of the drill bit ranges from 0.8 to 1.3 m/s. The measured torque includes the frictional torque between the drilling string and borehole wall, the viscous torque between the drilling string and seawater/drilling fluid, and the drilling torque between the drill bit and sediments. We subtracted the former two from the measured torque using the torque data during bottom-up rotating operations at several depths. Then, the shear stress was calculated from the drilling torque taking the configuration of the drill bit into consideration. The normal stress was estimated from the weight on bit data and the projected area of the drill bit. Assuming negligible cohesion, the frictional strength was obtained by dividing shear stress by normal stress. The results show a clear contrast in high-velocity frictional strength across the plate-boundary thrust: the friction coefficient of frontal prism sediments (hemipelagic mudstones) in hanging wall is 0.1-0.2, while that in subducting sediments (hemipelagic to pelagic mudstones and chert) in footwall increases to 0.2-0.4. The friction coefficient of smectite-rich pelagic clay in the plate-boundary thrust is ~0.1, which is consistent with that obtained from high-velocity (1.3 m/s) friction experiments and temperature measurements. We conclude that surface drilling torque provides useful data to obtain a continuous downhole frictional strength.

The Realization of Drilling Fault Diagnosis Based on Hybrid Programming with Matlab and VB

NASA Astrophysics Data System (ADS)

Wang, Jiangping; Hu, Yingcai

This paper presents a method using hybrid programming with Matlab and VB based on ActiveX to design the system of drilling accident prediction and diagnosis. So that the powerful calculating function and graphical display function of Matlab and visual development interface of VB are combined fully. The main interface of the diagnosis system is compiled in VB,and the analysis and fault diagnosis are implemented by neural network tool boxes in Matlab.The system has favorable interactive interface,and the fault example validation shows that the diagnosis result is feasible and can meet the demands of drilling accident prediction and diagnosis.

Thermal Alteration of Pyrite to Pyrrhotite During Earthquakes: New Evidence of Seismic Slip in the Rock Record

NASA Astrophysics Data System (ADS)

Yang, Tao; Dekkers, Mark J.; Chen, Jianye

2018-02-01

Seismic slip zones convey important information on earthquake energy dissipation and rupture processes. However, geological records of earthquakes along exhumed faults remain scarce. They can be traced with a variety of methods that establish the frictional heating of seismic slip, although each has certain assets and disadvantages. Here we describe a mineral magnetic method to identify seismic slip along with its peak temperature through examination of magnetic mineral assemblages within a fault zone in deep-sea sediments cored from the Japan Trench—one of the seismically most active regions around Japan—during the Integrated Ocean Drilling Program Expedition 343, the Japan Trench Fast Drilling Project. Fault zone sediments and adjacent host sediments were analyzed mineral magnetically, supplemented by scanning electron microscope observations with associated energy dispersive X-ray spectroscopy analyses. The presence of the magnetic mineral pyrrhotite appears to be restricted to three fault zones occurring at 697, 720, and 801 m below sea floor in the frontal prism sediments, while it is absent in the adjacent host sediments. Elevated temperatures and coseismic hot fluids as a consequence of frictional heating during earthquake rupture induced partial reaction of preexisting pyrite to pyrrhotite. The presence of pyrrhotite in combination with pyrite-to-pyrrhotite reaction kinetics constrains the peak temperature to between 640 and 800°C. The integrated mineral-magnetic, microscopic, and kinetic approach adopted here is a useful tool to identify seismic slip along faults without frictional melt and establish the associated maximum temperature.

Curiosity Drill After Drilling at Telegraph Peak

NASA Image and Video Library

2015-03-06

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover shows the rover's drill just after finishing a drilling operation at a target rock called "Telegraph Peak" on Feb. 24, 2015, the 908th Martian day, or sol, of the rover's work on Mars. Three sols later, a fault-protection action by the rover halted a process of transferring sample powder that was collected during this drilling. The image is in raw color, as recorded directly by the camera, and has not been white-balanced. The fault-protection event, triggered by an irregularity in electrical current, led to engineering tests in subsequent days to diagnose the underlying cause. http://photojournal.jpl.nasa.gov/catalog/PIA19145

A world-class target for ICDP drilling at Lake Nam Co, Tibetan Plateau, China: progresses and perspectives

NASA Astrophysics Data System (ADS)

Zhu, L.; Wang, J.; Daut, G.; Spiess, V.; Haberzettl, T.; Schulze, N.; Ju, J.; Lü, X.; Bergmann, F.; Haberkern, J.; Schwalb, A.; Mäusbacher, R.

2017-12-01

Lake Nam Co (ca. 2000 km2, 4718 m a.s.l., maximum depth: 100 m) is located at the interaction zone of the Westerlies and the Indian monsoon on the central Tibetan Plateau. It was part of a mega-lake during Marine Isotope Stage (MIS) 3 before the Last Glacial Maximum. A long term sedimentary record from Nam Co could therefore provide an excellent paleo-environmental sequence for regional and global comparative studies. This will to deepen our understanding of large scale atmospheric circulation shifts and the environmental links between the Tibetan Plateau at low latitudes and the North Atlantic region at high latitudes. A Nam Co deep drilling will fill the gap in two large scale ICDP/IODP drilling transects (N-S: Lake Baikal, Lake Qinghai, Bay of Bengal; W-E: Lake Van, Lake Issyk-Kul, South China Sea, Lake Towuti), which will show the great significance of monsoon dynamics on a long-term scale. Multidisciplinary researches have been conducted since 2005 by a Sino-German cooperative team. The progresses during the last decade are: 1) Detailed bathymetric surveying, including a shallow sediment profiler investigation (Innomar SES 2000 light, ca. 30 m sediment penetration); 2) Paleo-environmental reconstructions covering the past 24 ka; 3) Modern sediment distribution covering the entire lake; 4) Monitoring including water temperature profiles, sediment traps, seasonal airborne pollen collection; 5) Deep seismic survey penetrating up to 800 meters of lake sediments. Based on sediment rates from reference core NC08/01, seismic results show that an age of 500 ka may be reached at 500 m, and >1 Ma at the observed base. Faulting can be clearly detected in the seismic profiles, especially from MIS 5 to early Holocene, and shows the characteristics of normal faults or strike-slip faults. Both rotation of the layers and the close spacing, along with negative and positive offsets of the faults make a transtensional origin of the basin likely. An ICDP workshop proposal was approved this year (ID: ICDP-2017/10, http://www.icdp-online.org/projects/world/asia/lake-nam-co/). The workshop will likely be held in May 2018 in Beijing, where future scientific objectives, potential coring locations and logistics of a drilling campaign will be intensively discussed to ensure a successful drilling campaign in the near future.

Elemental Geochemistry of Samples From Fault Segments of the San Andreas Fault Observatory at Depth (SAFOD) Drill Hole

NASA Astrophysics Data System (ADS)

Tourscher, S. N.; Schleicher, A. M.; van der Pluijm, B. A.; Warr, L. N.

2006-12-01

Elemental geochemistry of mudrock samples from phase 2 drilling of the San Andreas Fault Observatory at Depth (SAFOD) is presented from bore hole depths of 3066 m to 3169 m and from 3292 m to 3368 m, which contain a creeping section and main trace of the fault, respectively. In addition to preparation and analysis of whole rock sample, fault grains with neomineralized, polished surfaces were hand picked from well-washed whole rock samples, minimizing the potential contamination from drilling mud and steel shavings. The separated fractions were washed in deionized water, powdered using a mortar and pestle, and analyzed using an Inductively Coupled Plasma- Optical Emission Spectrometer for major and minor elements. Based on oxide data results, systematic differences in element concentrations are observed between the whole rock and fault rock. Two groupings of data points are distinguishable in the regions containing the main trace of the fault, a shallow part (3292- 3316 m) and a deeper section (3320-3368 m). Applying the isocon method, assuming Zr and Ti to be immobile elements in these samples, indicates a volume loss of more than 30 percent in the shallow part and about 23 percent in the deep part of the main trace. These changes are minimum estimates of fault-related volume loss, because the whole rock from drilling samples contains variable amount of fault rock as well. Minimum estimates for volume loss in the creeping section of the fault are more than 50 percent when using the isocon method, comparing whole rock to plucked fault rock. The majority of the volume loss in the fault rocks is due to the dissolution and loss of silica, potassium, aluminum, sodium and calcium, whereas (based on oxide data) the mineralized surfaces of fractures appear to be enriched in Fe and Mg. The large amount of element mobility within these fault traces suggests extensive circulation of hydrous fluids along fractures that was responsible for progressive dissolution and leaching of the wall rock during faulting.

Operations Summary During Riserless Drilling to >7700 mbsl in the Japan Trench for IODP Expedition 343 & 343T: JFAST, and Discussion of the Relationship Between Drilling Parameters and Rock Damage.

NASA Astrophysics Data System (ADS)

Toy, V. G.; Maeda, L.; Toczko, S.; Eguchi, N.; Chester, F. M.; Mori, J. J.; Sawada, I.; Saruhashi, T.

2014-12-01

During IODP Expedition 343: The Japan Trench Fast Drilling Project (JFAST), two main boreholes were drilled from the D/V Chikyu in ~7000 m water depth. An uncored hole that penetrated to 850.5 meters below seafloor (mbsf) (total depth [TD] = 7740 meters below sea level [mbsl]) was documented using logging while drilling (LWD) tools. From an adjacent partially cored hole drilled to 844.5 mbsf (TD = 7734 mbsl) 21 cores were acquired that spanned the two main fault targets. The operations lasted 88 days. The drilling operation was very technically challenging. The drill string had to be withdrawn a number of times due to high seas, and technical issues; five holes were drilled (one abandoned after spud-in) and reoccupied in >6800 m water depth. A simple observatory was deployed in the wellhead installed during Exp 343 during the follow-up Exp 343T. In certain intervals during coring we mostly recovered loose, subrounded fine gravel clasts of the two major lithologies penetrated to those depths (silt and mudstones). We have performed particle shape and size analysis on these gravel aggregates. Particle shape variations apparent visually are not clearly quantified by conventional 'shape descriptors'. Variations in particle size distributions are apparent and we will discuss whether these relate to variations in drilling parameters.

Long-term, on-site borehole monitoring of gases released from an “active” fault system at 3.6km depth, TauTona Gold Mine, South Africa

NASA Astrophysics Data System (ADS)

Lippmann-Pipke, J.; Erzinger, J.; Zimmer, M.; Kujawa, C.; Boettcher, M. S.; Moller, H.; van Heerden, E.; Bester, A.; Reches, Z.

2009-12-01

Fluid transport and seismicity are interrelated. Fluids can trigger earthquakes and seismic activity can release fluids from rock formations. The study of this relationship requires direct and near-field observations at focal depth. The international DAFSAM-NELSAM*-projects focus on building the earthquake laboratory in deep gold mines in South Africa. Our DAFGAS-project (Drilling Active Faults - Gas Analytical System) aims to quantify the gases released during seismic events. One motivation for the project is to investigate the hypothesis that released fluids might be a nutrient supply for microbial ecosystems in active fault zones. Extensive underground activities started in 2004 with establishing a 25m2 cubby within the Pretorius fault zone at 3.6 km depth for the save installation of comprehensive technical equipment. For DAFGAS, subsequently two different gas analytical units were installed to measure gases collected in a 40 m long borehole crossing the fault. The DAFGAS Team and our collaborators overcame numerous technical problems. Since 2007 a dedicated air-conditioned box protects a mass spectrometer, pumps, a PC, a radon detector and electronics from the harsh underground environment. Since 2009 gas sensitive sensors and a data logger replace the spectrometer and the PC. In parallel the NELSAM project has installed 9 seismometers in a narrow network surrounding the gas collection system. The accelerometers and geophones record mining activities (e.g. drilling and ore-production blasts) as well as tens of mining-induced earthquakes (magnitude ≥ -4) on and around the Pretorius Fault each day. Data from three years is presented: Borehole temperature at 40m increased by about 0.8 °C/year to 52.3 °C; different scales of pressure variations on surface (869±5) mbar (three-week mean, maximal and minimal daily mean) and below surface (1130±15) mbar are explained by the barometric formula. The major gas concentrations are constant and air-like with 78 % N2, 21 % O2, 1 % Ar, while the trace gas components CO2, CH4, He and H2 show most interesting trends and variations on weekly, daily, hourly and on the minute-by-minute basis. They are interpreted by means of time series and cross correlation analysis. He, CH4, H2 and CO2 fluxes positively correlate with mining induced seismic activity. The CO2 flux additionally correlates with air pressure. Gas flow rates of H2 and CO2 from the formation into the borehole are calculated for periods with and without mining activity. In passive times they amount to ≤(0.1 and 0.3) μmol/min and increase to (0.7±0.1) μmol/min and (4.5±0.6) μmol/min during times of mining induced seismic activity, respectively. The installed gas sensitive electrodes (O2, CO2, CH4 and H2) are clearly more suitable for the underground environment than the mass spectrometer. Their sensitivity is currently only sufficient for H2 and CO2 measurements, however. *) Drilling Active Faults Laboratory in South African Mines - Natural Earthquake Laboratory in South African Mines

Core-Log-Seismic Integrative Study of a Subduction Zone Megasplay Fault -An Example from the Nobeoka Thrust, Shimanto Belt, Southwest Japan

NASA Astrophysics Data System (ADS)

Hamahashi, M.; Tsuji, T.; Saito, S.; Tanikawa, W.; Hamada, Y.; Hashimoto, Y.; Kimura, G.

2016-12-01

Investigating the mechanical properties and deformation patterns of megathrusts in subduction zones is important to understand the generation of large earthquakes. The Nobeoka Thrust, a fossilized megasplay fault in Kyushu Shimanto Belt, southwest Japan, exposes foliated fault rocks that were formed under the temperature range of 180-350° (Kondo et al., 2005). During the Nobeoka Thrust Drilling Project (2011), core samples and geophysical logging data were obtained recovering a continuous distribution of multiple fault zones, which provide the opportunity to examine their structure and physical properties in various scales (Hamahashi et al., 2013; 2015). By performing logging data analysis, discrete sample physical property measurements, and synthetic modeling of seismic reflections along the Nobeoka Thrust, we conducted core-log-seismic integrative study to characterize the effects of damage zone architecture and structural anisotropy towards the physical properties of the megasplay. A clear contrast in physical properties across the main fault core and surrounding damage zones were identified, where the fault rocks preserve the porosity of 4.8% in the hanging wall and 7.6% in the footwall, and P-wave velocity of 4.8 km/s and 4.2 km/s, respectively. Multiple sandstone-rich- and shale-rich damage zones were found from the drilled cores, in which velocity decreases significantly in the brecciated zones. The internal structure of these foliated fault rocks consist of heterogeneous lithology and texture, and velocity anisotropy ranges 1-18% (P-wave) and 1.5-80% (S-wave), affected by structural dip angle, foliation density, and sandstone/mudstone ratio. To evaluate the fault properties at the seismogenic depth, we developed velocity/earth models and synthetic modeling of seismic reflection using acoustic logs across the thrust and parameterized lithological and structural elements in the identified multiple damage zones.

Subsurface Resistivity Structures in and Around Strike-Slip Faults - Electromagnetic Surveys and Drillings Across Active Faults in Central Japan -

NASA Astrophysics Data System (ADS)

Omura, K.; Ikeda, R.; Iio, Y.; Matsuda, T.

2005-12-01

Electrical resistivity is important property to investigate the structure of active faults. Pore fluid affect seriously the electrical properties of rocks, subsurface electrical resistivity can be an indicator of the existence of fluid and distribution of pores. Fracture zone of fault is expected to have low resistivity due to high porosity and small gain size. Especially, strike-slip type fault has nearly vertical fracture zone and the fracture zone would be detected by an electrical survey across the fault. We performed electromagnetic survey across the strike-slip active faults in central Japan. At the same faults, we also drilled borehole into the fault and did downhole logging in the borehole. We applied MT or CSAMT methods onto 5 faults: Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2), western Nagano Ohtaki area(1984 Nagano-ken seibu earthquake (M=6.8), the fault did not appeared on the surface), Neodani fault which appeared by the 1891 Nobi earthquake (M=8.0), Atera fault which seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9), Gofukuji fault that is considered to have activated about 1200 years ago. The sampling frequencies of electrical and magnetic field were 2 - 1024Hz (10 frequencies) for CSAMT survey and 0.00055 - 384Hz (40 frequencies) for MT survey. The electromagnetic data were processed by standard method and inverted to 2-D resistivity structure along transects of the faults. Results of the survey were compared with downhole electrical logging data and observational descriptions of drilled cores. Fault plane of each fault were recognized as low resistivity region or boundary between relatively low and high resistivity region, except for Gofukuji fault. As for Gofukuji fault, fault was located in relatively high resistivity region. During very long elapsed time from the last earthquake, the properties of fracture zone of Gofukuji fault might changed from low resistivity properties as observed for other faults. Downhole electrical logging data were consistent to values of resistivity estimated by electromagnetic survey for each fault. The existence of relatively low and high resistivity regions in 2-D structure from electromagnetic survey was observed again by downhole logging at the correspondent portion in the borehole. Cores recovered from depthes where the electrical logging showed low resistivity were hardly fractured and altered from host rock which showed high resistivity. Results of electromagnetic survey, downhole electrical logging and observation of drilled cores were consistent to each other. In present case, electromagnetic survey is useful to explore the properties of fault fracture zone. In the further investigations, it is important to explore relationships among features of resistivity structure and geological and geophysical situations of the faults.

sRecovery Act: Geologic Characterization of the South Georgia Rift Basin for Source Proximal CO 2 Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waddell, Michael

This study focuses on evaluating the feasibility and suitability of using the Jurassic/Triassic (J/TR) sediments of the South Georgia Rift basin (SGR) for CO 2 storage in southern South Carolina and southern Georgia The SGR basin in South Carolina (SC), prior to this project, was one of the least understood rift basin along the east coast of the U.S. In the SC part of the basin there was only one well (Norris Lightsey #1) the penetrated into J/TR. Because of the scarcity of data, a scaled approach used to evaluate the feasibility of storing CO 2 in the SGR basin.more » In the SGR basin, 240 km (~149 mi) of 2-D seismic and 2.6 km2 3-D (1 mi2) seismic data was collected, process, and interpreted in SC. In southern Georgia 81.3 km (~50.5 mi) consisting of two 2-D seismic lines were acquired, process, and interpreted. Seismic analysis revealed that the SGR basin in SC has had a very complex structural history resulting the J/TR section being highly faulted. The seismic data is southern Georgia suggest SGR basin has not gone through a complex structural history as the study area in SC. The project drilled one characterization borehole (Rizer # 1) in SC. The Rizer #1 was drilled but due to geologic problems, the project team was only able to drill to 1890 meters (6200 feet) instead of the proposed final depth 2744 meters (9002 feet). The drilling goals outlined in the original scope of work were not met. The project was only able to obtain 18 meters (59 feet) of conventional core and 106 rotary sidewall cores. All the conventional core and sidewall cores were in sandstone. We were unable to core any potential igneous caprock. Petrographic analysis of the conventional core and sidewall cores determined that the average porosity of the sedimentary material was 3.4% and the average permeability was 0.065 millidarcy. Compaction and diagenetic studies of the samples determined there would not be any porosity or permeability at depth in SC. In Georgia there appears to be porosity in the J/TR section based on neutron log porosity values. The only zones in Rizer #1 that appear to be porous were fractured diabase units where saline formation water was flowing into the borehole. Two geocellular models were created for the SC and GA study area. Flow simulation modeling was performed on the SC data set. The injection simulation used the newly acquired basin data as well as the Petrel 3-D geologic model that included geologic structure. Due to the new basin findings as a result of the newly acquired data, during phase two of the modeling the diabase unit was used as reservoir and the sandstone units were used as caprock. Conclusion are: 1) the SGR basin is composed of numerous sub-basins, 2) this study only looked at portions of two sub-basins, 3) in SC, 30 million tonnes of CO 2 can be injected into the diabase units if the fracture network is continuous through the units, 4) due to the severity of the faulting there is no way of assuring the injected CO 2 will not migrate upward into the overlying Coastal Plain aquifers, 5) in Georgia there appears to porous zones in the J/TR sandstones, 6) as in SC there is faulting in the sub-basin and the seismic suggest the faulting extends upward into the Coastal Plain making that area not suitable for CO 2 sequestration, 7) the complex faulting observed at both study areas appear to be associated with transfer fault zones (Heffner 2013), if sub-basins in the Georgia portion of the SGR basin can be located that are far away from the transfer fault zones there is a strong possibility of sequestering CO 2 in these areas, and 9) the SGR basin covers area in three states and this project only studied two small areas so there is enormous potential for CO 2 sequestration in other portions the basin and further research needs to be done to find these areas.« less

Frictional properties of DFDP-1 Alpine Fault rocks under hydrothermal conditions and high shear strain

NASA Astrophysics Data System (ADS)

Niemeijer, André R.; Boulton, Carolyn; Toy, Virginia; Townend, John; Sutherland, Rupert

2015-04-01

The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65-75% of the total relative motion between the Australian and Pacific plates. Paleoseismic evidence of large-displacement surface-rupturing events, as well as an absence of measurable contemporary surface deformation, indicates that the fault slips mostly in quasi-periodic large-magnitude earthquakes (< Mw 8.0). To understand the mechanics of earthquakes, it is important to study the evolution of frictional properties of the fault rocks under conditions representative of the potential hypocentral depth. Here, we present data obtained on drill core samples of rocks that surround the principal slip zone(s) (PSZ) of the Alpine Fault and the PSZ itself. The drill core samples were obtained during phase 1 of the Deep Fault Drilling Project (DFDP-1) in 2011 at relatively shallow depths (down to ~150 m). Simulated fault gouges were sheared under elevated pressure and temperature conditions in a hydrothermal ring shear apparatus. We performed experiments at temperatures of 25, 150, 300, 450 ° C, and 600 oC. Using the shallow geothermal gradient of 63 ° C/km determined in DFDP-1, our highest temperature corresponds to a depth of ~7 km (Sutherland et al. 2012); it would correspond to 10 km depth using a more moderate geotherm of 45 oC/km (Toy et al. 2010). All samples show a transition from velocity-strengthening behavior, i.e. a positive value of (a-b), to velocity-weakening behavior, i.e. a negative value of (a-b) at a temperature of 150 ° C. The transition depends on the absolute value of sliding velocity, with velocity-weakening dominating at lower sliding velocities. At 600 oC, velocity-strengthening dominates at low sliding velocity, whereas the high-velocity steps are all velocity-weakening. Moreover, shear stress depends linearly on effective normal stress at 600 oC, indicating that shearing is essentially frictional and that no transition to ductile (normal stress independent) flow has occurred. Thus, depending on the background (nucleation) strain rate, our data indicate that the Alpine Fault should be able to generate earthquakes at all temperatures above room temperature. However, at the highest temperature investigated (600 oC), the transition to velocity-weakening is postponed to slip rates above 10 mm/s (strain rate ~10-2 s-1). This observation, combined with the absence of strength recovery after long holds, suggests that seismic slip may propagate into regions of the fault unlikely to nucleate earthquakes. We propose that in our porous gouges, thermally activated processes operate simultaneously with granular flow, postponing ductile flow to higher temperatures or lower strain rates. Sutherland, R., V.G. Toy, J. Townend, S.C. Cox, J.D. Eccles, D.R. Faulkner, D.J. Prior, R.J.Norris, E. Mariani, C. Boulton, B.M. Carpenter, C.D. Menzies, T.A. Little, M. Hasting, G.De Pascale, R.M. Langridge, H.R. Scott, Z. Reid-Lindroos, B. Fleming (2012), Drilling reveals fluid control on architecture and rupture of the Alpine Fault, New Zealand, Geology,40, 1143-1146, doi:10.1130/G33614.1. Toy, V.G., Craw, D., Cooper, A.F., and R.J. Norris (2010), Thermal regime in the central Alpine Fault zone, New Zealand: Constraints from microstructures, biotite chemistry and fluid inclusion data, Tectonophysics, doi:10.1016/j.tecto.2009.12.013

Characterization of Seismogenic Faults of Central Japan by Geophysical Survey and Drilling

NASA Astrophysics Data System (ADS)

Ikeda, R.; Omura, K.; Matsuda, T.

2004-12-01

Integrated investigations on seismogenic faults by geophysical survey and drilling are indispensable to better understand deep structure and physical properties of a fault fracture zone. In central Japan, three large active faults, Neodani, Atotsugawa and Atera faults, exist and are remarkable for research because of the potentiality of a scale of magnitude 7 to 8 class earthquake and the different characteristics of the seismogenic activities in these faults. Each individual fault shows its own characteristic features, which may reflect different stages in an earthquake cycle. High seismicity is concentrated with a clear lineation on and around the Atotsugawa fault, which is recognized as aftershocks from the latest event of the 1858 Hida earthquake (M=7.0). On the other hand, extremely low seismicity is found around the Atera fault, of which some parts seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9). As an example of the results of study at the Atera fault, we obtained a wide variety of fault structures, composed materials, states of crustal stress and strengths of the fault from the geophysical survey (resistivity and gravity) and in-situ borehole experiments. Our findings are as follows: (1) The fracture zone around the Atera fault shows a very wide and complex fracture structure, from approximately 1 km to 4 km wide. (2) The average slip rate was estimated to be 5.3 m /1000 yr by the distribution of basalt in the age of 1.5 Ma as determined by radioactive dating. We inferred that the Atera fault has been repeatedly active in recent geologic time; however, it is in a very weak state at present. (3) Stress magnitude decreases in the area closer to the center of the fracture zone. These are important results to evaluate fault activity. Recent in-situ downhole measurements and coring through active faults have provided us with new insights into the physical properties of fault zones. In the vicinity of the epicenter of the 1995 Hyogo-ken Nanbu (Kobe) earthquake, we have conducted an integrated study by using 1,000 m to 1,800 m deep drilling wells. In particular, the Nojima-Hirabayashi borehole was drilled to a depth of 1,838 m and directly intersected the Nojima fault. Three possible fault strands were detected at depths of 1,140 m, 1,313 m and 1,800 m. Major results obtained from this study include the following: (1) Shear stress around the fault zone is very small, and the orientation of the maximum horizontal compression is perpendicular to the surface trace of faults. (2) From the results of a heat flow study, the lower cut-off depth of the aftershocks was estimated to be roughly 300 _E#8249;C. (3) Cores were classified into several types of fault rocks, and an asymmetric distribution pattern of these fault rocks in the fracture zones was identified. (4) Country rock is characterized by very low permeability and high strength. (5) Resistivity structure can be explained by a model of a fault extending to greater depths but with low resistivity. The integrated study by geophysical survey, drilling and core analyses, downhole measurements and long-term monitoring directly within these fault zones, provide us with characteristic features and dynamics of active faults.

Magnetic properties of cores from the Wenchuan Earthquake Fault Scientific Drilling Hole-2 (WFSD-2), China

NASA Astrophysics Data System (ADS)

Zhang, L., Jr.; Sun, Z.; Li, H.; Cao, Y.; Ye, X.; Wang, L.; Zhao, Y.; Han, S.

2015-12-01

During an earthquake, seismic slip and frictional heating may cause the physical and chemical alterations of magnetic minerals within the fault zone. Rock magnetism provides a method for understanding earthquake dynamics. The Wenchuan earthquake Fault Scientific Drilling Project (WFSD) started right after 2008 Mw7.9 Wenchuan earthquake, to investigate the earthquake faulting mechanism. Hole 2 (WFSD-2) is located in the Pengguan Complex in the Bajiaomiao village (Dujiangyan, Sichuan), and reached the Yingxiu-Beichuan fault (YBF). We measured the surface magnetic susceptibility of the cores in WFSD-2 from 500 m to 1530 m with an interval of 1 cm. Rocks at 500-599.31 m-depth and 1211.49-1530 m-depth are from the Neoproterozoic Pengguang Complex while the section from 599.31 m to 1211.49 m is composed of Late Triassic sediments. The magnetic susceptibility values of the first part of the Pengguan Complex range from 1 to 25 × 10-6 SI, while the second part ranges from 10 to 200 × 10-6 SI, which indicate that the two parts are not from the same rock units. The Late Triassic sedimentary rocks have a low magnetic susceptibility values, ranging from -5 to 20 × 10-6 SI. Most fault zones coincide with the high value of magnetic susceptibility in the WFSD-2 cores. Fault rocks, mainly fault breccia, cataclasite, gouge and pseudotachylite within the WFSD-2 cores, and mostly display a significantly higher magnetic susceptibility than host rocks (5:1 to 20:1). In particular, in the YBF zone of the WFSD-2 cores (from 600 to 960 m), dozens of stages with high values of magnetic susceptibility have been observed. The multi-layered fault rocks with high magnetic susceptibility values might indicate that the YBF is a long-term active fault. The magnetic susceptibility values change with different types of fault rocks. The gouge and pseudotachylite have higher values of magnetic susceptibility than other fault rocks. Other primary rock magnetism analyses were then performed to investigate the mechanisms. We consider that the principal mechanism for the high magnetic susceptibility of these fault rocks is most likely the production of new magnetite from iron-bearing paramagnetic minerals (such as silicates or clays). These new magnetites might originate from frictional heating on a seismic fault slip plane or seismic fluid during an earthquake.

Physical and chemical properties of the creeping fault ruptured in the 2008 Mw 7.9 Wenchuan earthquake from the WFSD-3P cores, eastern Tibet

NASA Astrophysics Data System (ADS)

He, X.; Li, H.; Wang, H.; Zhang, L., Jr.; Chevalier, M. L.

2016-12-01

The Anxian-Guanxian Fault (AGF) is a frontal fault of the Longmen Shan thrust belt, which ruptured during the 2008 Mw 7.9 Wenchuan earthquake in the eastern margin of the Tibetan Plateau. This study focuses on the 551.54 m-depth cores from the shallow hole of the Wenchuan earthquake Fault Scientific Drilling Project WFSD-3P which drilled across the AGF. Detailed core petrological study, geophysical downhole logs, rock magnetism and XRF analyses were conducted to explore the physical and chemical properties of the AGF, which is helpful to reveal the faulting mechanism and provides a reference to determine behaviors of other faults. The AGF zone in the WFSD-3p mainly consists of fault gouge and fault breccia from 442.41-510.14 m depth cores ( 48 m thick), with a dip angle of 45°. Fine-grained fault gouge and pressolution structures are commonly observed under optical microscope, which indicate the AGF is in creeping. The average magnetic susceptibility value of the fault gouge is slightly less than that of the country rock and the main magnetic carriers are pyrrhotite on the basis of low-temperature magnetic measurement. This phenomenon is different from the characteristics of other seismic faults with high magnetic susceptibility value due to heating by rapid slip friction. In terms of chemical properties, the fault gouge is characterized by relatively low concentration of iron, manganese and calcium, as well as high concentration of copper, vanadium and sulfur according to XRF analyses. In addition, the fluid samples are reductive, with a PH value of 10 and a negative value for redox potential. Combined with the grey-green sandstone along the rupture zone, they indicate that the AGF creeping is in a reducing environment. There are partly locked areas with clasts by rapid slip during the earthquake in the AGF zone. This observation was present at the boundary of the Triassic and Jurassic units ( 507 m depth), near the bottom of the fault zone. It represents the location of the Principle Slip Zone (PSZ) of the 2008 Wenchuan earthquake and shows earthquakes might occur along a creeping fault in certain cases.

Frictional, Hydraulic, and Acoustic Properties of Alpine Fault DFDP-1 Core

NASA Astrophysics Data System (ADS)

Carpenter, B. M.; Ikari, M.; Kitajima, H.; Kopf, A.; Marone, C.; Saffer, D. M.

2012-12-01

The Alpine Fault, a transpressional plate-boundary fault transecting the South Island of New Zealand, is the current focus of the Deep Fault Drilling Project (DFDP), a major fault zone drilling initiative. Phase 1 of this project included 2 boreholes that penetrated the active fault at depths of ˜100 m and ˜150 m, and provided a suite of core samples crossing the fault. Here, we report on laboratory measurements of frictional strength and constitutive behavior, permeability, and ultrasonic velocities for a suite of the recovered core samples We conducted friction experiments on powdered samples in a double-direct shear configuration at room temperature and humidity. Our results show that over a range of effective normal stresses from 10-100 MPa, friction coefficients are ~0.60-0.70, and are similar for all of the materials we tested. Rate-stepping tests document velocity-weakening behavior in the majority of wall rock samples, whereas the principal slip surface (PSS) and an adjacent clay-rich cataclasite exhibit velocity-strengthening behavior. We observe significant rates of frictional healing in all of our samples, indicating that that the fault easily regains its strength during interseismic periods. Our results indicate that seismic slip is not likely to nucleate in the clay-rich PSS at shallow depths, but might nucleate and propagate on the gouge/wall rock interface. We measured permeability using a constant head technique, on vertically oriented cylindrical mini-cores (i.e. ˜45 degrees to the plane of the Alpine Fault). We conducted these tests in a triaxial configuration, under isotropic stress conditions and effective confining pressures from ~2.5 - 63.5 MPa. We conducted ultrasonic wavespeed measurements concurrently with the permeability measurements to determine P- and S-wave velocities from time-of-flight. The permeability of all samples decreases systematically with increasing effective stress. The clay-rich cataclasite (1.37 x 10-19 m2) and PSS (1.62 x 10-20 m2) samples exhibit the lowest permeabilities. The cataclasite, and wall rock mylonite and gravel samples, all exhibit permeabilities > 10-18 m2. We also observe that permeability of the cataclasites appears to decrease with proximity to the active fault zone. Our laboratory measurements are consistent with borehole slug tests that show the fault is a hydraulic barrier, and suggest that fault rock permeability is sufficiently low to facilitate transient pore pressure effects during rapid slip, including thermal pressurization and dilatancy hardening. Elastic wave velocity increases systematically with increasing effective stress. We find the lowest P-wave velocities in clay-rich, poorly lithified samples from within and near the active fault, including hanging wall cataclasite, fault gouge, and footwall gravel. Our results are consistent with borehole logging data that show an increase in P-wave velocity from the mylonite into the competent cataclasites, and a decrease in P-wave velocity through the clay-rich cataclasite and into the fault zone.

Real time drilling mud gas response to small-moderate earthquakes in Wenchuan earthquake Scientific Drilling Hole-1 in SW China

NASA Astrophysics Data System (ADS)

Gong, Zheng; Li, Haibing; Tang, Lijun; Lao, Changling; Zhang, Lei; Li, Li

2017-05-01

We investigated the real time drilling mud gas of the Wenchuan earthquake Fault Scientific Drilling Hole-1 and their responses to 3918 small-moderate aftershocks happened in the Longmenshan fault zone. Gas profiles for Ar, CH4, He, 222Rn, CO2, H2, N2, O2 are obtained. Seismic wave amplitude, energy density and static strain are calculated to evaluate their power of influence to the drilling site. Mud gases two hours before and after each earthquake are carefully analyzed. In total, 25 aftershocks have major mud gas response, the mud gas concentrations vary dramatically immediately or minutes after the earthquakes. Different gas species respond to earthquakes in different manners according to local lithology encountered during the drill. The gas variations are likely controlled by dynamic stress changes, rather than static stress changes. They have the seismic energy density between 10-5 and 1.0 J/m3 whereas the static strain are mostly less than 10-8. We suggest that the limitation of the gas sources and the high hydraulic diffusivity of the newly ruptured fault zone could have inhibited the drilling mud gas behaviors, they are only able to respond to a small portion of the aftershocks. This work is important for the understanding of earthquake related hydrological changes.

Results from Geothermal Logging, Air and Core-Water Chemistry Sampling, Air Injection Testing and Tracer Testing in the Northern Ghost Dance Fault, YUCCA Mountain, Nevada, November 1996 to August 1998

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lecain, G.D.; Anna, L.O.; Fahy, M.F.

1998-08-01

Geothermal logging, air and core-water chemistry sampling, air-injection testing, and tracer testing were done in the northern Ghost Dance Fault at Yucca Mountain, Nevada, from November 1996 to August 1998. The study was done by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy. The fault-testing drill room and test boreholes were located in the crystal-poor, middle nonlithophysal zone of the Topopah Spring Tuff, a tuff deposit of Miocene age. The drill room is located off the Yucca Mountain underground Exploratory Studies Facility at about 230 meters below ground surface. Borehole geothermal logging identified a temperature decreasemore » of 0.1 degree Celsius near the Ghost Dance Fault. The temperature decrease could indicate movement of cooler air or water, or both, down the fault, or it may be due to drilling-induced evaporative or adiabatic cooling. In-situ pneumatic pressure monitoring indicated that barometric pressure changes were transmitted from the ground surface to depth through the Ghost Dance Fault. Values of carbon dioxide and delta carbon-13 from gas samples indicated that air from the underground drill room had penetrated the tuff, supporting the concept of a well-developed fracture system. Uncorrected carbon-14-age estimates from gas samples ranged from 2,400 to 4,500 years. Tritium levels in borehole core water indicated that the fault may have been a conduit for the transport of water from the ground surface to depth during the last 100 years.« less

Fault Zone Resistivity Structure and Monitoring at the Taiwan Chelungpu Drilling Project from AMT data

NASA Astrophysics Data System (ADS)

Chiang, C.-W.; Unsworth, M. J.; Chen, C.-S.; Chen, C.-C.; Lin, A.-T.; Hsu, H.-L.

2009-04-01

The Chi-Chi earthquake occurred on September 21st, 1999 in the Western Foothills of central Taiwan. This Mw=7.6 earthquake produced a 90 km long surface rupture and caused severe damage across Taiwan. The coseismic displacement on the Chelungpu fault was one of the largest ever observed. The Taiwan Chelungpu drilling project (TCDP) began in 2003 and resulted in a 2,000 m well that recovered cores from the fault zone at A-hole and finished in 2005 with two boreholes (A-hole and B-hole) being completed. The Chelungpu fault that caused the Chi-Chi earthquake was observed in the core at a depth of 1,111 m (FAZ1111). Another fault zone (Sanyi Fault - FAZ1710) was observed at depths of 1,500~1,710 m. Since the electrical resistivity of rocks is sensitive to the presence of fluids, geophysical methods that remotely sense sub-surface resistivity, such as Magnetotellurics (MT), can be a powerful tool in investigating the fluid distribution in the shallow crust. The effectiveness of MT in imaging fault zones has been demonstrated by studies of the San Andreas Fault zone in California, the U.S. and elsewhere. In magnetotellurics, the depth of exploration increases as the signal frequency decreases. Thus for imaging shallow fault zone structure at the TCDP site, the higher frequency audio-magnetotelluric (AMT) method is the most suitable. In this paper, AMT data collected at the TCDP site from 2004 to 2006 are presented. Spatial and temporal variations are described and interpreted in terms of the tectonic setting. Audio-magnetotelluric (AMT) measurements were used to investigate electrical resistivity structure at the TCDP site from 2004~2006. These data show a geoelectric strike direction of N15°E to N30°E. Inversion and forward modeling of the AMT data were used to generate a 1-D resistivity model that has a prominent low resistivity zone (< 10 ohm-m) between depths of 1,100 and 1,500 m. When combined with porosity measurements, the AMT measurements imply that the ground water has a resistivity of 0.55 ohm-m at the depth of the fault zone. Time variations in the measured AMT data were observed from 2004~2005 with maximum changes of 43% in apparent resistivity and 18° in phase. The change in apparent resistivity is greatest in the 1,000~100 Hz frequency band. These frequencies are sensitive to the resistivity structure of the upper 500 m of the hanging wall of the Chelungpu Fault. The decrease in resistivity over time appears to be robust and could be caused by an increase in porosity and a re-distribution of the groundwater.

Drilling the leading edge of the mantle wedge and the underlying metamorphic sole of the Samail Ophiolite: Hole BT1B, Oman Drilling Project

NASA Astrophysics Data System (ADS)

Morishita, T.; Kelemen, P. B.; Coggon, J. A.; Harris, M.; Matter, J. M.; Michibayashi, K.; Takazawa, E.; Teagle, D. A. H.

2017-12-01

Hole BT1B (23°21.861' N, 58°10.957' E) was drilled by the Oman Drilling Project (OmDP) on the north side of Wadi Mansah in the Samail ophiolite, Oman. OmDP is an international collaboration supported by the International Continental Scientific Drilling Program, Deep Carbon Observatory, NSF, IODP, JAMSTEC, and the European, Japanese, German and Swiss Science Foundations, with in-kind support in Oman from the Ministry of Regional Municipalities and Water Resources, Public Authority of Mining, Sultan Qaboos University, and the German University of Technology. Hole BT1B was cored from 6 to 23 March 2017, to a depth of 300.05 m. The outer surfaces of the cores were imaged and described onsite before being curated, boxed and shipped to the IODP drill ship Chikyu. Hole BT1B sampled carbonated peridotite (listvenite), 2 carbonate-veined serpentinite bands at 80-100 and 180-185 m depth, a few cm of ultracataclasite and 70 cm of fault gouge at 197 m depth, followed by 103 m metamorphic sole. Onboard Chikyu, BT1B underwent X-ray computed tomography (CT) and multi-sensor logging, imaging and spectroscopy, macroscopic and thin section observations, physical properties measurements, and XRF, XRD and ICP-MS analyses. 1st authors of abstracts reporting initial results are Beinlich (matrix characteristics), de Obeso (modeling mass transfer), Godard (XRF and ICP-MS whole rock data), Greenberger (infrared spectroscopy), Johnson (XRF core scanner), Kelemen (overall petrology), Manning (veins), and Michibayashi (X-ray CT). Listvenite is composed of carbonate + quartz + Fe-oxyhydroxides, + minor relict spinel ± chromian mica (fuchsite). The mineralogy suggests formation at < 150°C. The bulk rock density is similar to that of gabbro but the P-wave velocity is generally higher. Rock textures suggest viscous deformation, while additional brittle deformation is recorded by older veins and younger breccias and faults. The metamorphic sole consists of fine-grained to microcrystalline metasediments and metabasalts. Metasediments have qtz + plag and mica + amphibole layers, with minor epidote, and become less abundant and poorer in K downhole. Metabasalts are massive, epidote-rich with less qtz and mica. Actinolite and possible pumpellyite needles in quartz suggest low T/P. Sediment and basalt compositions resemble alkali basalt.

Mud Gas Logging In A Deep Borehole: IODP Site C0002, Nankai Trough Accretionary Prism

NASA Astrophysics Data System (ADS)

Toczko, S.; Hammerschmidt, S.; Maeda, L.

2014-12-01

Mud logging, a tool in riser drilling, makes use of the essentially "closed-circuit" drilling mud flow between the drilling platform downhole to the bit and then back to the platform for analyses of gas from the formation in the drilling mud, cuttings from downhole, and a range of safety and operational parameters to monitor downhole drilling conditions. Scientific riser drilling, with coincident control over drilling mud, downhole pressure, and returning drilling mud analyses, has now been in use aboard the scientific riser drilling vessel Chikyu since 2009. International Ocean Discovery Program (IODP) Expedition 348, as part of the goal of reaching the plate boundary fault system near ~5000 mbsf, has now extended the deep riser hole (Hole C0002 N & P) to 3058.5 mbsf. The mud gas data discussed here are from two approximately parallel boreholes, one a kick-off from the other; 860-2329 mbsf (Hole C0002N) and 2163-3058 mbsf (Hole C0002P). An approximate overlap of 166 m between the holes allows for some slight depth comparison between the two holes. An additional 55 m overlap at the top of Hole C0002P exists where a 10-5/8-inch hole was cored, and then opened to 12-1/4-inch with logging while drilling (LWD) tools (Fig. 1). There are several fault zones revealed by LWD data, confirmed in one instance by coring. One of the defining formation characteristics of Holes C0002 N/P are the strongly dipping bedding planes, typically exceeding 60º. These fault zones and bedding planes can influence the methane/ethane concentrations found in the returning drilling mud. A focused comparison of free gas in drilling mud between one interval in Hole C0002 P, drilled first with a 10 5/8-inch coring bit and again with an 12 ¼-inch logging while drilling (LWD) bit is shown. Hole C0002N above this was cased all the way from the sea floor to the kick-off section. A fault interval (in pink) was identified from the recovered core section and from LWD resistivity and gamma. The plot of methane and ethane free gas (C1 and C2; ppmv) shows that the yield of free gas (primarily methane) was greater when the LWD bit returned to open the cored hole to a greater diameter. One possible explanation for this is the time delay between coring and LWD operations; approximately 3 days passed between the end of coring and the beginning of LWD (25-28 December 2013).

IODP Expedition 338: NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2

NASA Astrophysics Data System (ADS)

Moore, G. F.; Kanagawa, K.; Strasser, M.; Dugan, B.; Maeda, L.; Toczko, S.

2014-01-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is designed to investigate fault mechanics and seismogenesis along a subduction megathrust, with objectives that include characterizing fault slip, strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout an active plate boundary system. Integrated Ocean Drilling Program (IODP) Expedition 338 was planned to extend and case riser Hole C0002F from 856 to 3600 meters below the seafloor (m b.s.f.). Riser operations extended the hole to 2005.5 m b.s.f., collecting logging-while-drilling (LWD) and measurement-while-drilling, mud gas, and cuttings data. Results reveal two lithologic units within the inner wedge of the accretionary prism that are separated by a prominent fault zone at ~ 1640 m b.s.f. Due to damage to the riser during unfavorable winds and strong currents, riser operations were suspended, and Hole C0002F left for re-entry during future riser drilling operations. Contingency riserless operations included coring at the forearc basin site (C0002) and at two slope basin sites (C0021 and C0022), and LWD at one input site (C0012) and at three slope basin sites (C0018, C0021 and C0022). Cores and logs from these sites comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution, gas hydrates in the forearc basin, and recent activity of the shallow megasplay fault zone system and associated submarine landslides.

Reinforcement and Drill by Microcomputer.

ERIC Educational Resources Information Center

Balajthy, Ernest

1984-01-01

Points out why drill work has a role in the language arts classroom, explores the possibilities of using a microcomputer to give children drill work, and discusses the characteristics of a good software program, along with faults found in many software programs. (FL)

Three-Dimensional Geologic Model of Complex Fault Structures in the Upper Seco Creek Area, Medina and Uvalde Counties, South-Central Texas

USGS Publications Warehouse

Pantea, Michael P.; Cole, James C.; Smith, Bruce D.; Faith, Jason R.; Blome, Charles D.; Smith, David V.

2008-01-01

This multimedia report shows and describes digital three-dimensional faulted geologic surfaces and volumes of the lithologic units of the Edwards aquifer in the upper Seco Creek area of Medina and Uvalde Counties in south-central Texas. This geologic framework model was produced using (1) geologic maps and interpretations of depositional environments and paleogeography; (2) lithologic descriptions, interpretations, and geophysical logs from 31 drill holes; (3) rock core and detailed lithologic descriptions from one drill hole; (4) helicopter electromagnetic geophysical data; and (5) known major and minor faults in the study area. These faults were used because of their individual and collective effects on the continuity of the aquifer-forming units in the Edwards Group. Data and information were compared and validated with each other and reflect the complex relationships of structures in the Seco Creek area of the Balcones fault zone. This geologic framework model can be used as a tool to visually explore and study geologic structures within the Seco Creek area of the Balcones fault zone and to show the connectivity of hydrologic units of high and low permeability between and across faults. The software can be used to display other data and information, such as drill-hole data, on this geologic framework model in three-dimensional space.

Fracture structures of active Nojima fault, Japan, revealed by borehole televiewer imaging

NASA Astrophysics Data System (ADS)

Nishiwaki, T.; Lin, A.

2017-12-01

Most large intraplate earthquakes occur as slip on mature active faults, any investigation of the seismic faulting process and assessment of seismic hazards require an understanding of the nature of active fault damage zones as seismogenic source. In this study, we focus on the fracture structures of the Nojima Fault (NF) that triggered the 1995 Kobe Mw 7.2 earthquake using ultrasonic borehole televiewer (BHTV) images from a borehole wall. The borehole used in this study was drilled throughout the NF at 1000 m in depth by a science project of Drilling into Fault Damage Zone(DFDZ) in 2016 (Lin, 2016; Miyawaki et al., 2016). In the depth of <230 m of the borehole, the rocks are composed of weak consolidated sandstone and conglomerate of the Plio-Pleistocene Osaka-Group and mudstone and sandstone of the Miocene Kobe Group. The basement rock in the depth of >230 m consist of pre-Neogene granitic rock. Based on the observations of cores and analysis of the BHTV images, the main fault plane was identified at a depth of 529.3 m with a 15 cm thick fault gouge zone and a damage zone of 100 m wide developed in the both sides of the main fault plane. Analysis of the BHTV images shows that the fractures are concentrated in two groups: N45°E (Group-1), parallel to the general trend of the NF, and another strikes N70°E (Group-2), oblique to the fault with an angle of 20°. It is well known that Riedel shear structures are common within strike-slip fault zones. Previous studies show that the NF is a right-lateral strike-slip fault with a minor thrust component, and that the fault damage zone is characterized by Riedel shear structures dominated by Y shears (main faults), R shears and P foliations (Lin, 2001). We interpret that the fractures of Group (1) correspond to Y Riedel fault shears, and those of Group (2) are R shears. Such Riedel shear structures indicate that the NF is a right-lateral strike-slip fault which is activated under a regional stress field oriented to the direction close to east-west, coincident with that inferred from geophysical observations (Tsukahara et al., 2001), seismic inversion results (Katao, 1997) and geological structures (Lin, 2001).Katao et al., 1997. J. Phys. Earth, 45, 105.Lin, 2016. AGU, Fall Meeting.Lin, 2001. J. Struc. Geo., 23, 1167.Miyawaki and Uchida, 2016. AGU, Fall Meeting.Tsukahara et al., 2001. Isl. Arc, 10, 261.

RIO Tinto Faulted Volcanosedimentary Deposits as Analog Habitats for Extant Subsurface Biospheres on Mars: A Synthesis of the MARTE Drilling Project Geobiology Results

NASA Technical Reports Server (NTRS)

Fernandez-Remolar, D. C.; Prieto-Ballesteros, O.; Rodriquez, N.; Davila, F.; Stevens, T.; Amils, R.; Gomez-Elvira, J.; Stoker, C.

2005-01-01

Geochemistry and mineralogy on Mars surface characterized by the MER Opportunity Rover suggest that early Mars hosted acidic environments in the Meridiani Planum region [1, 2]. Such extreme paleoenvironments have been suggested to be a regional expression of the global Mars geological cycle that induced acidic conditions by sulfur complexation and iron buffering of aqueous solutions [3]. Under these assumptions, underground reservoirs of acidic brines and, thereby, putative acidic cryptobiospheres, may be expected. The MARTE project [4, 5] has performed a drilling campaign to search for acidic and anaerobic biospheres in R o Tinto basement [6] that may be analogs of these hypothetical communities occurring in cryptic habitats of Mars. This Rio Tinto geological region is characterized by the occurrence of huge metallic deposits of iron sulfides [7]. Late intensive diagenesis of rocks driven by a compressive regimen [8] largely reduced the porosity of rocks and induced a cortical thickening through thrusting and inverse faulting and folding. Such structures play an essential role in transporting and storing water underground as any other aquifers do in the Earth. Once the underground water reservoirs of the Ro Tinto basement contact the hydrothermal pyrite deposits, acidic brines are produced by the release of sulfates and iron through the oxidation of sulfides [9].

Interferometric imaging of the San Andreas Fault at Parkfield Using a Massive VSP

NASA Astrophysics Data System (ADS)

Chavarria, J.; Goertz, A.; Karrenbach, M.; Paulsson, B.

2006-12-01

The San Andreas Fault Observatory at Depth (SAFOD) has the goal of investigating the physical processes controlling earthquakes in central California at Parkfield. The observatory consists of a deep well, that intersected the San Andreas Fault at seismogenic depths of ~3.2 km, where recurring microearthquake activity takes place. Previous to the drilling of Phase II, that intersected the fault at the end of Summer 2005, a long array of seismometers was deployed in the deeper part of the well to characterize the fault structure and to aid the monitoring activities of the natural seismicity. The Massive VSP array consisted of 80 three component seismometers that were deployed during April and May 2005. During this period of time we recorded active data from 13 explosions used to refine the velocity models that improved the locations of target events. In addition to this, we continuously monitored passive data from the natural earthquake activity in the area that was dominated by the Parkfield 2004 event aftershock sequence. During the recording time of this project we were able to record one of the target earthquakes of the SAFOD project as well as recently discovered non-volcanic tremor. The data recorded by this deep array of seismometers has provided important information to characterize the structure of the fault at scale that is comparable to the scale of the geologic observations. These observations, derived during drilling of the well, consist of cores and cuttings as well as geophysical logs. With the use of the borehole array of seismometers we have been able to directly correlate this lithologic information with seismic phases observed in the VSP data. This has lead to better understanding the nature of the scattering that takes place in this complex fault zone. Seismic reflections in the dataset were analyzed with Kirchhoff imaging methods to determine a partial image of the San Andreas Fault at depth. Due to the low density distribution of sources in the study area the illumination volume is limited but still shows clear signals originating from sub-vertical structures associated to the strands of the San Andreas fault inferred from high resolution earthquake location. The existing Kirchhoff imaging methods have been complemented with the use of interferometric imaging by which we extract the Green's function of the data recorded by the array. This takes place with the use of correlation analysis of both active and passive data resulting in a dataset where each downhole receiver acts as a virtual source. This analysis has provided a refined image of the structure of the San Andreas Fault at seismogenic depths with which a better understanding of the system can be achieved.

Constraints on Neogene deformation in the southern Terror Rift from calcite twinning analyses of veins within the ANDRILL MIS core, Victoria Land Basin, Antarctica

NASA Astrophysics Data System (ADS)

Paulsen, T. S.; Demosthenous, C.; Wilson, T. J.; Millan, C.

2009-12-01

The ANDRILL MIS (McMurdo Ice Shelf) Drilling Project obtained over 1200 meters of Neogene sedimentary and volcanic rocks in 2006/2007. Systematic fracture logging of the AND-1B core identified 1,475 natural fractures, i.e. pre-existing fractures in the rock intersected by coring. The most abundant natural fractures are normal faults and calcite veins; reverse faults, brecciated zones, and sedimentary intrusions are also present. In order to better understand Neogene deformation patterns within the southern Terror Rift, we have been conducting strain analyses on mechanically twinned calcite within healed fractures in the drill core. Twinning strains using all of the data from each sample studied to date range from 2% to 10%. The cleaned data (20% of the largest magnitude deviations removed) typically show ≤30% negative expected values, consistent with a single deformation episode or multiple ~coaxial deformation episodes. The majority of the samples record horizontal extension, similar to strain patterns expected in a normal fault regime and/or vertical sedimentary compaction in a continental rift system. The morphology, width, and intensity of twins in the samples suggest that twinning typically occurred at temperatures <170° C. Twinning intensities suggest differential stress magnitudes that caused the twinning ranged from 216 to 295 MPa.

A dense, intersecting array of normal faults on the outer shelf off Southern Costa Rica, associated with subducting Quepos ridge

NASA Astrophysics Data System (ADS)

Silver, E. A.; Kluesner, J. W.; Gibson, J. C.; Bangs, N. L.; McIntosh, K. D.; von Huene, R.; Orange, D.; Ranero, C. R.

2012-12-01

Use of narrow, fixed swath multibeam data with high sounding densities has allowed order of magnitude improvement in image resolution with EM122 multibeam and backscatter data, as part of a 3D seismic study west of the Osa Peninsula. On the outer shelf, along the projection of the subducting Quepos Ridge, we mapped a dense array of faults cutting an arcuate, well-layered set of outcropping beds in the backscatter imagery (mosaicked at 2 m), with roughly N-S and E-W trends. The N-S trends dominate, and show inconsistent offsets, implying that the faults are normal and not strike-slip. The faults also show normal displacement in the 3D seismic data, consistent with the surface interpretation. The outcropping beds (of late Pleistocene age, based on Expedition 334 drilling), may have been truncated during the late Pleistocene low sea-level stand. The outermost shelf (edged by arcuate bathymetric contours) does not show these folded beds, as it was below wave base and buried by a thin sediment layer. However, narrow lines of small pockmarks and mounds follow the fault trends exactly, indicating that fluid flow through the faults is expressed at the surface, including a gas plume that extends to the sea-surface. The almost unprecedented increase in resolution of the EM122 data allows us to infer that the N-S, E-W grid of faults overlying the NE-trending Quepos Ridge projection (and NE directed subduction) formed by extensional arching above the ridge, not by collisional slip lines at a rigid indenter (as proposed earlier based on sandbox models). The extensional fault pattern also facilitates fluid and gas flow through the sedimentary section.

Frictional melt generated by the 2008 Mw 7.9 Wenchuan earthquake and its faulting mechanisms

NASA Astrophysics Data System (ADS)

Wang, H.; Li, H.; Si, J.; Sun, Z.; Zhang, L.; He, X.

2017-12-01

Fault-related pseudotachylytes are considered as fossil earthquakes, conveying significant information that provide improved insight into fault behaviors and their mechanical properties. The WFSD project was carried out right after the 2008 Wenchuan earthquake, detailed research was conducted in the drilling cores. 2 mm rigid black layer with fresh slickenlines was observed at 732.6 m in WFSD-1 cores drilled at the southern Yingxiu-Beichuan fault (YBF). Evidence of optical microscopy, FESEM and FIB-TEM show it's frictional melt (pseudotachylyte). In the northern part of YBF, 4 mm fresh melt was found at 1084 m with similar structures in WFSD-4S cores. The melts contain numerous microcracks. Considering that (1) the highly unstable property of the frictional melt (easily be altered or devitrified) under geological conditions; (2) the unfilled microcracks; (3) fresh slickenlines and (4) recent large earthquake in this area, we believe that 2-4 mm melt was produced by the 2008 Wenchuan earthquake. This is the first report of fresh pseudotachylyte with slickenlines in natural fault that generated by modern earthquake. Geochemical analyses show that fault rocks at 732.6 m are enriched in CaO, Fe2O3, FeO, H2O+ and LOI, whereas depleted in SiO2. XRF results show that Ca and Fe are enriched obviously in the 2.5 cm fine-grained fault rocks and Ba enriched in the slip surface. The melt has a higher magnetic susceptibility value, which may due to neoformed magnetite and metallic iron formed in fault frictional melt. Frictional melt visible in both southern and northern part of YBF reveals that frictional melt lubrication played a major role in the Wenchuan earthquake. Instead of vesicles and microlites, numerous randomly oriented microcracks in the melt, exhibiting a quenching texture. The quenching texture suggests the frictional melt was generated under rapid heat-dissipation condition, implying vigorous fluid circulation during the earthquake. We surmise that during earthquakes vigorous fluid influx within fault zone, likely dissipating the frictional heat and resulting in rapid temperature drop, may facilitate the solidification of melt and hamper the aftermost fault slip. Meanwhlie, the high temperature fluid-rock interaction may play an important role in the chemical elements migrating in fault zones.

Frictional power dissipation on plate boundary faults: Implications for coseismic slip propagation at near-surface depths

NASA Astrophysics Data System (ADS)

Ikari, M.; Kopf, A.; Saffer, D. M.; Marone, C.; Carpenter, B. M.

2013-12-01

The general lack of earthquake slip at shallow (< ~4 km) depths on plate-boundary faults suggests that they creep stably, a behavior associated with laboratory observations that disaggregated fault gouges commonly strengthen with increasing sliding velocity (i.e. velocity-strengthening friction), which precludes strain energy release via stress drops. However, the 2011 Tohoku earthquake demonstrated that coseismic rupture and slip can sometimes propagate to the surface in subduction zones. Surface rupture is also known to occur on other plate boundary faults, such as the Alpine Fault in New Zealand. It is uncertain how the extent of coseismic slip propagation from depth is controlled by the frictional properties of the near-surface portion of major faults. In these situations, it is common for slip to localize within gouge having a significant component of clay minerals, which laboratory experiments have shown are generally weak and velocity strengthening. However, low overall fault strength should facilitate coseismic slip, while velocity-strengthening behavior would resist it. In order to investigate how frictional properties may control the extent of coseismic slip propagation at shallow depths, we compare frictional strength and velocity-dependence measurements using samples from three subduction zones known for hosting large magnitude earthquakes. We focus on samples recovered during scientific drilling projects from the Nankai Trough, Japan, the Japan Trench in the region of the Tohoku earthquake, and the Middle America Trench, offshore Costa Rica; however we also include comparisons with other major fault zones sampled by drilling. In order to incorporate the combined effects of overall frictional strength and friction velocity-dependence, we estimate shear strength as a function of slip velocity (at constant effective normal stress), and integrate this function to obtain the areal power density, or frictional power dissipation capability of the fault zone. We also explore the role of absolute shear stress level before arrival of a propagating rupture. Preliminary results show that weak, velocity-strengthening fault zones have a low net power density, but are unlikely to contribute to instability via dynamic stress drops unless they are initially very close to failure. By contrast, strong and velocity-weakening faults will tend to resist coseismic slip by consuming energy if stresses are initially low; however their velocity-weakening nature means that they can support a stress drop even if relatively far below their failure strength.

Magnetic insights on seismogenic processes from scientific drilling of fault

NASA Astrophysics Data System (ADS)

Ferre, E. C.; Chou, Y. M.; Aubourg, C. T.; Li, H.; Doan, M. L.; Townend, J.; Sutherland, R.; Toy, V.

2017-12-01

Modern investigations through scientific drilling of recently seismogenic faults have provided remarkable insights on the physics of rupture processes. Following devastating earthquakes, several drilling programs focused since 1995 on the Nojima, Chelungpu, San Andreas, Wenchuan, Nankai Trough, Japan Trench and New Zealand Alpine faults. While these efforts were all crowned with success largely due to the multidisciplinarity of investigations, valuable insights were gained from rock magnetism and paleomagnetism and deserve to be highlighted. Continuous logging of magnetic properties allows detection of mineralogical and chemical changes in the host rock and fault zone particularly in slip zones, whether these are caused by frictional melting, elevation of temperature, ultracataclasis, or post-seismic fluid rock interaction. Further magnetic experiments on discrete samples including magnetic susceptibility, natural remanent magnetization, hysteresis properties, isothermal remanent magnetization acquisition and first order reversal curves, provide additional constrains on the nature, concentration and grain size of magnetic carriers. These experiments typically also inform on magnetization processes by thermal, chemical, or electrical mechanisms. Magnetic fabrics are generally not investigated on fault rocks from drill cores primarily in an effort to conserve the recovered core. However, recent methodological developments now would allow chemically non-destructive anisotropy of magnetic susceptibility (AMS) measurements to be performed on small 3.5 mm cubes. The mini-AMS method could provide crucial information on the kinematics of frictional melts produced during recent or ancient earthquakes and therefore would constrain the corresponding focal mechanisms. Finally, demagnetization experiments of the natural remanent magnetization (NRM) are one of the most powerful items in the magnetic toolkit because they provide chronological constrains on magnetization processes. Hence paleomagnetic experiments on fault rocks offer a unique opportunity to distinguish between recently active and ancient slip zones.

Core Across the San Andreas Fault at SAFOD - Photographs, Physical Properties Data, and Core-Handling Procedures

NASA Astrophysics Data System (ADS)

Kirschner, D. L.; Carpenter, B.; Keenan, T.; Sandusky, E.; Sone, H.; Ellsworth, B.; Hickman, S.; Weiland, C.; Zoback, M.

2007-12-01

Core samples were obtained that cross three faults of the San Andreas Fault Zone north of Parkfield, California, during the summer of 2007. The cored intervals were obtained by sidetracking off the SAFOD Main Hole that was rotary drilled across the San Andreas in 2005. The first cored interval targeted the pronounced lithologic boundary between the Salinian terrane and the Great Valley and Franciscan formations. Eleven meters of pebbly conglomerate (with minor amounts of fine sands and shale) were obtained from 3141 to 3152 m (measured depth, MD). The two conglomerate units are heavily fractured with many fractures having accommodated displacement. Within this cored interval, there is a ~1m zone with highly sheared, fine-grained material, possibly ultracataclasite in part. The second cored interval crosses a creeping segment of a fault that has been deforming the cemented casing of the adjacent Main Hole. This cored interval sampled the fault 100 m above a seismogenic patch of M2 repeating earthquakes. Thirteen meters of core were obtained across this fault from 3186 to 3199 m (MD). This fault, which is hosted primarily in siltstones and shales, contains a serpentinite body embedded in a highly sheared shale and serpentinite-bearing fault gouge unit. The third cored interval crosses a second creeping fault that has also been deforming the cemented casing of the Main Hole. This fault, which is the most rapidly shearing fault in the San Andreas fault zone based on casing deformation, contains multiple fine- grained clay-rich fault strands embedded in highly sheared shales and lesser deformed sandstones. Initial processing of the cores was carried out at the drill site. Each core came to the surface in 9 meter-long aluminum core barrels. These were cut into more manageable three-foot sections. The quarter-inch-thick aluminum liner of each section was cut and then split apart to reveal the 10 cm diameter cores. Depending on the fragility and porosity of the rock, the drilling fluid was removed either by washing with dilute calcium chloride brine (to approximately match the salinity of the formation fluids) or by gently scraping away drilling mud on the core surface. Once cleaned, each core section was photographed to very high resolution on a Geotek Multi- Sensor Core Logging (MSCL) system. This system was also used to determine the bulk density and magnetic susceptibility of each section. The 25 MB high-resolution photographs and the raw and processed physical properties data were then uploaded to the ICDP web server in Potsdam for public access (http://safod.icdp- online.org). The cores will be archived at the Gulf Coast Repository of the Integrated Ocean Drilling Program in College Station, TX. The MSCL photographs, physical property measurements, and other related data, such as geophysical logs, will be integrated using CoreWall, and will be on display at the meeting. All samples, data, and imagery are available to the science community.

Hydraulic properties of samples retrieved from the Wenchuan earthquake Fault Scientific Drilling Project Hole-1 (WFSD-1) and the surface rupture zone: Implications for coseismic slip weakening and fault healing

NASA Astrophysics Data System (ADS)

Chen, Jianye; Yang, Xiaosong; Ma, Shengli; Yang, Tao; Niemeijer, André

2016-07-01

In this study, we report the hydraulic properties of samples recovered from the first borehole of the Wenchuan earthquake Fault Scientific Drilling and from outcrops associated with the surface rupture zone of the 2008 Wenchuan earthquake. Compositional and microstructural analyses have also been performed on selected samples. Using the pore pressure oscillation method, the permeability measurements show that (1) fault gouge samples have low permeabilities, decreasing from 2 × 10-18 m2 at an effective pressure (Pe) of 10 MPa (equivalent to an in situ depth of 600 m) to 9 × 10-21 m2 at 155 MPa. (2) Intact and cemented samples are impermeable with permeabilities less than 2 × 10-20 m2 at 10 MPa. (3) Fractured samples have variable permeabilities, ranging from 3 × 10-15 to 1 × 10-20 m2 at 10 MPa, and are most insensitive to changes in the effective pressure. (4) Granitic cataclasites have a moderate permeability at low pressure (i.e., 10-16 to 10-17 m2 at 10 MPa); which decreases rapidly with increasing Pe. Hydraulic conduction of the fault is believed to be influenced by the permeability of the fractures developed, which is controlled by the density, aperture, and/or connectivity of the fractures. Microstructural and compositional analyses of the samples indicate that the fault zone heals through chemically mediated fracture closure related to mineral precipitation, possibly assisted by pressure solution of stressed fracture asperities. Although other weakening mechanisms remain possible, our laboratory measurements combined with numerical modeling reveal that thermal/thermochemical pressurization, perhaps leading to gouge fluidization, played an important role in the dynamic weakening of the Wenchuan earthquake, at least in the study area.

Recent exploration and drilling activity in the Lafayette Bol. mex. basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, F.W. Jr.

1995-10-01

The 1984 discovery of thick Bol. mex. gas sands at the Broussard Field initiated an intense exploration play. This activity and further evaluation of existing fields has centered in and around Lafayette, Louisiana. Since 1984 drilling for Bol. mex. sands has resulted in the discovery of several new fields and extensions. Cumulative production from fields within the basin is 425 BCF gas and 20 million barrels of condensate through 1994. The quest for these high yield reservoirs, which average over 200 feet in thickness in some fault blocks, continues unabated. There are four wells currently drilling near Lafayette with Bol.more » mex. sands as the main objective. One of the most exciting ventures is being drilled by Vastar in the city of Lafayette. All the drilling wells are located in the Lafayette Bol. mex. basin which is a large depositional center of Oligocene {open_quotes}Frio{close_quotes} sands centering just west of Lafayette. Approximately 2000 feet thick, the basin is a sequence of alternating sands and shales deposited in a deep marine environment. It is flanked on the north by a large growth fault which forms the northern limit of the basin. Basinward, a series of additional growth faults strike south of the subparallel to the northern edge of the Bol. mex. basin. The production seems to be associated with structures along the strike of the growth faulting. The fields which produce from the Bol. mex. interval are Scott, Broussard, West Ridge, Duson-Ridge, North Broussard, Milton, Maurice, North Maurice and Perry Point.« less

Integrated characterization of the geologic framework of a contaminated site in West Trenton, New Jersey

USGS Publications Warehouse

Ellefsen, Karl J.; Burton, William C.; Lacombe, Pierre J.

2012-01-01

Fractured sedimentary bedrock and groundwater at the former Naval Air Warfare Center in West Trenton, New Jersey (United States of America) are contaminated with chlorinated solvents. Predicting contaminant migration or removing the contaminants requires an understanding of the geology. Consequently, the geologic framework near the site was characterized with four different methods having different spatial scales: geologic field mapping, analyses of bedrock drill core, analyses of soil and regolith, and S-wave refraction surveys. A fault zone is in the southeast corner of the site and separates two distinct sedimentary formations; the fault zone dips (steeply) southeasterly, strikes northeasterly, and extends at least 550 m along its strike direction. Drill core from the fault zone is extensively brecciated and includes evidence of tectonic contraction. Approximately 300 m east of this fault zone is another fault zone, which offsets the contact between the two sedimentary formations. The S-wave refraction surveys identified both fault zones beneath soil and regolith and thereby provided constraints on their lateral extent and location.

The Toa Baja Drilling Project and current studies in Puerto Rican geology: Introduction and summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larue, D.K.

1991-03-01

This volume concerns information learned by drilling the Toa Baja well on the north coast of Puerto Rico, and current studies of Puerto Rican geology and tectonics. The Toa Baja Drillsite is located in the North Coast basin of Puerto Rico about 10 km west of San Juan. The hole was spudded on August 23, 1989, and plugged and abandoned on November 7, 1989 at a total depth of 2,704m. Two lithologies were encountered during drilling: an upper series consisting of Oligocene-Miocene shallow-water limestone and sandstone facies, and a lower series consisting of Eocene deep-water volcaniclastic strata, including some lavamore » flows or shallow intrusions, pelagic marls, and altered igneous rocks or coarse-grained sandstones. Principal findings made during drilling include: (1) the important unconformity separating the upper and lower series at about 579 m; (2) 8 faults defined clearly by dipmeter log; (3) changes in rock type probably associated with reflection events in seismic reflection profiles crossing the drillsite; (4) confirmation of overall low geothermal gradients and heat flow, but presence of a thermal anomaly near 2683 m; (5) documentation of high paleogeothermal gradients using petrographic, isotopic, X-Ray diffraction and electron microprobe studies; (6) presence of fractures indicating a current extensional tectonic setting. Current studies in the Puerto Rico region include: (1) paleomagnetic evidence for late Miocene counterclockwise rotation; (2) geochemical evolution of Cretaceous and Eocene igneous rocks; (3) evidence of transtension in the northeast Caribbean plate boundary zone; (4) results of studies of ancient fault zones on Puerto Rico; and (5) stratigraphic studies of the Tertiary of Puerto Rico.« less

Final Project Report: Imaging Fault Zones Using a Novel Elastic Reverse-Time Migration Imaging Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lianjie; Chen, Ting; Tan, Sirui

Imaging fault zones and fractures is crucial for geothermal operators, providing important information for reservoir evaluation and management strategies. However, there are no existing techniques available for directly and clearly imaging fault zones, particularly for steeply dipping faults and fracture zones. In this project, we developed novel acoustic- and elastic-waveform inversion methods for high-resolution velocity model building. In addition, we developed acoustic and elastic reverse-time migration methods for high-resolution subsurface imaging of complex subsurface structures and steeply-dipping fault/fracture zones. We first evaluated and verified the improved capabilities of our newly developed seismic inversion and migration imaging methods using synthetic seismicmore » data. Our numerical tests verified that our new methods directly image subsurface fracture/fault zones using surface seismic reflection data. We then applied our novel seismic inversion and migration imaging methods to a field 3D surface seismic dataset acquired at the Soda Lake geothermal field using Vibroseis sources. Our migration images of the Soda Lake geothermal field obtained using our seismic inversion and migration imaging algorithms revealed several possible fault/fracture zones. AltaRock Energy, Inc. is working with Cyrq Energy, Inc. to refine the geologic interpretation at the Soda Lake geothermal field. Trenton Cladouhos, Senior Vice President R&D of AltaRock, was very interested in our imaging results of 3D surface seismic data from the Soda Lake geothermal field. He planed to perform detailed interpretation of our images in collaboration with James Faulds and Holly McLachlan of University of Nevada at Reno. Using our high-resolution seismic inversion and migration imaging results can help determine the optimal locations to drill wells for geothermal energy production and reduce the risk of geothermal exploration.« less

Drilling into seismogenic zones of M2.0 - M5.5 earthquakes in deep South African gold mines (DSeis)

NASA Astrophysics Data System (ADS)

Ogasawara, Hiroshi; Durrheim, Raymond; Yabe, Yasuo; Ito, Takatoshi; van Aswegen, Gerrie; Cichowicz, Artur; Onstott, Tullis; Kieft, Tom; Boettcher, Margaret; Wiemer, Stefan; Ziegler, Martin; Janssen, Christoph; Shapiro, Serge; Gupta, Harsh; Dight, Phil

2016-04-01

Several times a year, mining-induced earthquakes with magnitudes equal to or larger than 2 take place only a few tens of meters away from active workings in South African gold mines at depths of up to 3.4 km. The largest event recorded in mining regions, a M5.5 earthquake, took place near Orkney, South Africa on 5 August 2014, with the upper edge of the activated fault being only some hundred meters below the nearest mine workings (3.0 km depth). This is one of the rare events for which detailed seismological data are available, both from surface and underground seismometers and strainmeters, allowing for a detailed seismological analysis and comparison with in-situ observed data. Therefore, this earthquake calls for drilling to investigate the seismogenic zones before aftershocks diminish. Such a project will have a significantly better spatial coverage (including nuclei of ruptures, strong motion sources, asperities, and rupture edges) than drilling in seismogenic zones of natural large earthquakes and will be possible with a lower risk and at much smaller costs. In seismogenic zones in a critical state of stress, it is difficult to delineate reliably the local spatial variation in both directions and magnitudes of principal stresses (3D full stress tensor) reliably. However, we have overcome this problem. We are able to numerically model stress better than before, enabling us to orient boreholes so that the chance of stress-induced damage during stress measurement is minimized, and enabling us to measure the full 3D stress tensor successively in a hole within reasonable time even when stresses are as large as those expected in seismogenic zones. Better recovery of cores with less stress-induced damage during drilling is also feasible. These will allow us to address key scientific questions in earthquake science and associated deep biosphere activities which have remained elusive. We held a 4-day workshop sponsored by ICDP and Ritsumeikan University in October/November 2015, which confirmed the great scientific value as well as technical feasibility, flexibility, and cost-effectiveness of drilling into the targets which have already been well seismologically probed. The value will be maximized if we combine outcomes from a limited number of holes drilled from 3 km depth into the M5.5 seismogenic zones (~ 4 km depth) with larger number of boreholes from mining horizons into the other targets (M~2 faults) already extensively exhumed by mining or which will be in future. We could have additional inputs during the 2015 AGU Fall Meeting period. We intend to start drilling before the M5.5 aftershocks diminish or mining around the M2.8 fault starts to alter stress considerably.

Elastic Properties of Subduction Zone Materials in the Large Shallow Slip Environment for the Tohoku 2011 Earthquake: Laboratory data from JFAST Core Samples

NASA Astrophysics Data System (ADS)

Jeppson, T.; Tobin, H. J.

2014-12-01

The 11 March 2011 Tohoku-Oki earthquake (Mw=9.0) produced large displacements of ~50 meters near the Japan Trench. In order to understand earthquake propagation and slip stabilization in this environment, quantitative values of the real elastic properties of fault zones and their surrounding wall rock material is crucial. Because elastic and mechanical properties of faults and wallrocks are controlling factors in fault strength, earthquake generation and propagation, and slip stabilization, an understanding of these properties and their depth dependence is essential to understanding and accurately modeling earthquake rupture. In particular, quantitatively measured S-wave speeds, needed for estimation of elastic properties, are scarce in the literature. We report laboratory ultrasonic velocity measurements performed at elevated pressures, as well as the calculated dynamic elastic moduli, for samples of the rock surrounding the Tohoku earthquake principal fault zone recovered by drilling during IODP Expedition 343, Japan Trench Fast Drilling Project (JFAST). We performed measurements on five samples of gray mudstone from the hanging wall and one sample of underthrust brown mudstone from the footwall. We find P- and S-wave velocities of 2.0 to 2.4 km/s and 0.7 to 1.0 km/s, respectively, at 5 MPa effective pressure. At the same effective pressure, the hanging wall samples have shear moduli ranging from 1.4 to 2.2 GPa and the footwall sample has a shear modulus of 1.0 GPa. While these values are perhaps not surprising for shallow, clay-rich subduction zone sediments, they are substantially lower than the 30 GPa commonly assumed for rigidity in earthquake rupture and propagation models [e.g., Ide et al., 1993; Liu and Rice, 2005; Loveless and Meade, 2011]. In order to better understand the elastic properties of shallow subduction zone sediments, our measurements from the Japan Trench are compared to similar shallow drill core samples from the Nankai Trough, Costa Rica, Cascadia, and Barbados ridge subduction zones. We find that shallow subduction zone sediments in general have similarly low rigidity. These data provide important ground-truth values that can be used to parameterize fault slip models addressing the problem of shallow, tsunamigenic propagation of megathrust earthquakes.

Hydrothermal minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Indonesia

USGS Publications Warehouse

Moore, Diane E.; Hickman, S.; Lockner, D.A.; Dobson, P.F.

2001-01-01

Detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike-slip Great Sumatran fault zone near Silangkitang, North Sumatra, supports a model for enhanced hydrothermal circulation adjacent to this major plate-boundary fault. Two wells (A and C) were drilled nearly vertically ??1 km southwest of the eastern (i.e., the principal) fault trace, and the third, directional well (B) was drilled eastward from the site of well A to within ??100 m of the principal fault trace. The examined core samples come from depths of 1650-2120 m at measured well temperatures of 180-320 ??C. The samples collected near the principal fault trace have the highest temperatures, the largest amount of secondary pore space that correlates with high secondary permeability, and the most extensive hydrothermal mineral development. Secondary permeability and the degree of hydrothermal alteration decrease toward the southwestern margin of the fault zone. These features indicate episodic, localized flow of hot, possibly CO2-rich fluids within the fault zone. The microstructure populations identified in the core samples correlate to the subsidiary fault patterns typical of strike-slip faults. The geothermal reservoir appears to be centered on the fault zone, with the principal fault strands and adjoining, highly fractured and hydrothermally altered rock serving as the main conduits for vertical fluid flow and advective heat transport from deeper magmatic sources.

Fluid-rock interaction during a large earthquake recorded in fault gouge: A case study of the Nojima fault, Japan

NASA Astrophysics Data System (ADS)

Bian, D.; Lin, A.

2016-12-01

Distinguishing the seismic ruptures during the earthquake from a lot of fractures in borehole core is very important to understand rupture processes and seismic efficiency. In particular, a great earthquake like the 1995 Mw 7.2 Kobe earthquake, but again, evidence has been limited to the grain size analysis and the color of fault gouge. In the past two decades, increasing geological evidence has emerged that seismic faults and shear zones within the middle to upper crust play a crucial role in controlling the architectures of crustal fluid migration. Rock-fluid interactions along seismogenic faults give us a chance to find the seismic ruptures from the same event. Recently, a new project of "Drilling into Fault Damage Zone" has being conducted by Kyoto University on the Nojima Fault again after 20 years of the 1995 Kobe earthquake for an integrated multidisciplinary study on the assessment of activity of active faults involving active tectonics, geochemistry and geochronology of active fault zones. In this work, we report on the signature of slip plane inside the Nojima Fault associated with individual earthquakes on the basis of trace element and isotope analyses. Trace element concentrations and 87Sr/86Sr ratios of fault gouge and host rocks were determined by an inductively coupled plasma mass spectrometer (ICP-MS) and thermal ionization mass spectrometry (TIMS). Samples were collected from two trenches and an outcrop of Nojima Fault which. Based on the geochemical result, we interpret these geochemical results in terms of fluid-rock interactions recorded in fault friction during earthquake. The trace-element enrichment pattern of the slip plane can be explained by fluid-rock interactions at high temperature. It also can help us find the main coseismic fault slipping plane inside the thick fault gouge zone.

A Test Case for the Source Inversion Validation: The 2014 ML 5.5 Orkney, South Africa Earthquake

NASA Astrophysics Data System (ADS)

Ellsworth, W. L.; Ogasawara, H.; Boettcher, M. S.

2017-12-01

The ML5.5 earthquake of August 5, 2014 occurred on a near-vertical strike slip fault below abandoned and active gold mines near Orkney, South Africa. A dense network of surface and in-mine seismometers recorded the earthquake and its aftershock sequence. In-situ stress measurements and rock samples through the damage zone and rupture surface are anticipated to be available from the "Drilling into Seismogenic Zones of M2.0-M5.5 Earthquakes in South African gold mines" project (DSeis) that is currently progressing toward the rupture zone (Science, doi: 10.1126/science.aan6905). As of 24 July, 95% of drilled core has been recovered from a 427m-section of the 1st hole from 2.9 km depth with minimal core discing and borehole breakouts. A 2nd hole is planned to intersect the fault at greater depth. Absolute differential stress will be measured along the holes and frictional characteristics of the recovered core will be determined in the lab. Surface seismic reflection data and exploration drilling from the surface down to the mining horizon at 3km depth is also available to calibrate the velocity structure above the mining horizon and image reflective geological boundaries and major faults below the mining horizon. The remarkable quality and range of geophysical data available for the Orkney earthquake makes this event an ideal test case for the Source Inversion Validation community using actual seismic data to determine the spatial and temporal evolution of earthquake rupture. We invite anyone with an interest in kinematic modeling to develop a rupture model for the Orkney earthquake. Seismic recordings of the earthquake and information on the faulting geometry can be found in Moyer et al. (2017, doi: 10.1785/0220160218). A workshop supported by the Southern California Earthquake Center will be held in the spring of 2018 to compare kinematic models. Those interested in participating in the modeling exercise and the workshop should contact the authors for additional information.

From Target Selection to Post-Stimulation Analysis: Example of an Unconventional Faulted Reservoir

NASA Astrophysics Data System (ADS)

LeCalvez, J. H.; Williams, M.; Xu, W.; Stokes, J.; Moros, H.; Maxwell, S. C.; Conners, S.

2011-12-01

As the global balance of supply and demand forces the hydrocarbon industry toward unconventional resources, technology- and economics-driven shale oil and gas production is gaining momentum throughout many basins worldwide. Production from such unconventional plays is facilitated by massive hydraulic fracturing treatments aimed at increasing permeability and reactivating natural fractures. Large-scale faulting and fracturing partly control stress distribution, hence stimulation-derived hydraulically-induced fracture systems development. Therefore, careful integrated approaches to target selection, treatment staging, and stimulation methods need to be used to economically maximize ultimate hydrocarbon recovery. We present a case study of a multistage, multilateral stimulation project in the Fort Worth Basin, Texas. Wells had to be drilled within city limits in a commercially developing building area. Well locations and trajectories were determined in and around large-scale faults using 3D surface seismic with throws varying from seven to thirty meters. As a result, three horizontal wells were drilled in the Lower Barnett Shale section, 150 m apart with the central well landed about 25 m shallower than the outside laterals. Surface seismic indicates that the surface locations are on top of a major fault complex with the lateral sections drilling away from the major fault system and through a smaller fault. Modeling of the borehole-based microseismic monitoring options led to the selection of an optimum set of configurations given the operational restrictions faced: monitoring would mainly take place using a horizontal array to be tractored downhole and moved according to the well and stage to be monitored. Wells were completed using a perf-and-plug approach allowing for each stimulation stage to obtain a precise orientation of the various three-component accelerometers of the monitoring array as well as the calibration of the velocity model used to process the microseismic data acquired. Real-time microseismic monitoring allowed (i) to avoid the water-bearing formation below the zone of interest, (ii) to bypass the faulted zone, and (iii) to modify as needed the perforation and stimulation plans. Completion led to an initial gas production of over 3 MMCF/day each. Early decline rates confirm successful completion in avoiding the faulted areas. Initial observations of the slickwater fracturing stimulation treatments for these three wells using an integrated approach involving mechanical modelling calibrated using microseismic data indicate that (i) a long bi-wing-like fracture system initiated prior to being followed by a complex fracture network; thus, explaining the fact that some events are mapped relatively far away from the injection site, (ii) proppant generally settled down in the near wellbore area during the fracture network development due to rapid decrease of fluid flow velocity away from the injection side. Initial b-value results seem to indicate that the target reservoir is naturally fractured and that the influence of a large fault system in the vicinity of the treated zone could be asserted.

Elastic anisotropy of core samples from the Taiwan Chelungpu Fault Drilling Project (TCDP): direct 3-D measurements and weak anisotropy approximations

NASA Astrophysics Data System (ADS)

Louis, Laurent; David, Christian; Špaček, Petr; Wong, Teng-Fong; Fortin, Jérôme; Song, Sheng Rong

2012-01-01

The study of seismic anisotropy has become a powerful tool to decipher rock physics attributes in reservoirs or in complex tectonic settings. We compare direct 3-D measurements of P-wave velocity in 132 different directions on spherical rock samples to the prediction of the approximate model proposed by Louis et al. based on a tensorial approach. The data set includes measurements on dry spheres under confining pressure ranging from 5 to 200 MPa for three sandstones retrieved at a depth of 850, 1365 and 1394 metres in TCDP hole A (Taiwan Chelungpu Fault Drilling Project). As long as the P-wave velocity anisotropy is weak, we show that the predictions of the approximate model are in good agreement with the measurements. As the tensorial method is designed to work with cylindrical samples cored in three orthogonal directions, a significant gain both in the number of measurements involved and in sample preparation is achieved compared to measurements on spheres. We analysed the pressure dependence of the velocity field and show that as the confining pressure is raised the velocity increases, the anisotropy decreases but remains significant even at high pressure, and the shape of the ellipsoid representing the velocity (or elastic) fabric evolves from elongated to planar. These observations can be accounted for by considering the existence of both isotropic and anisotropic crack distributions and their evolution with applied pressure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rush, Jason; Holubnyak, Yevhen; Watney, Willard

This DOE-funded project evaluates the utility of seismic volumetric curvature (VC) for predicting stratal and structural architecture diagnostic of paleokarst reservoirs. Of special interest are applications geared toward carbon capture, utilization, and storage (CCUS). VC has been championed for identifying faults (offset <¼ λ) that cannot be imaged by conventional 3-D seismic attributes such as coherence. The objective of this research was to evaluate VC-techniques for reducing uncertainties in reservoir compartmentalization studies and seal risk assessments especially for saline aquifers. A 2000-ft horizontal lateral was purposefully drilled across VC-imaged lineaments—interpreted to record a fractured and a fault-bounded doline—to physically confirmmore » their presence. The 15-mi² study area is located in southeastern Bemis-Shutts Field, which is situated along the crest of the Central Kansas Uplift (CKU) in Ellis County, Kansas. The uppermost Arbuckle (200+ ft) has extensive paleokarst including collapsed paleocaverns and dolines related to exceedingly prolonged pre-Simpson (Sauk–Tippecanoe) and/or pre-Pennsylvanian subaerial exposure. A lateral borehole was successfully drilled across the full extent (~1100 ft) of a VC-inferred paleokarst doline. Triple combo (GR-neutron/density-resistivity), full-wave sonic, and borehole micro-imager logs were successfully run to TD on drill-pipe. Results from the formation evaluation reveal breccias (e.g., crackle, mosaic, chaotic), fractures, faults, vugs (1-6"), and unaffected host strata consistent with the pre-spud interpretation. Well-rounded pebbles were also observed on the image log. VC-inferred lineaments coincide with 20–80-ft wide intervals of high GR values (100+ API), matrix-rich breccias, and faults. To further demonstrate their utility, VC attributes are integrated into a geocellular modeling workflow: 1) to constrain the structural model; 2) to generate facies probability grids, and; 3) to collocate petrophysical models to separate-vug rock fabrics along solution-enlarged fault and fracture systems. Simulation-based studies demonstrate a potential alternative field development model for developing CO 2 storage sites that target carbonate reservoirs overprinted by paleokarst. Simulation results for this complex reservoir indicate that individual fault blocks could function as discrete containers for CO 2 storage thereby reducing the risk of plume migration outside the legally defined extent of the permitted storage site. Vertically extensive, anastomosing, solution-enlarged fault/fracture systems — infilled by clay-rich sediments — would operate as non-to-low permeability vertical "curtains" that restrict CO 2 movement beyond the confines of the CO 2 storage site. Such a location could be developed in a checker-board fashion with CO 2 injection operations occurring in one block and surveillance operations occurring in the adjacent block. Such naturally partitioned reservoirs may be ideal candidates for reducing risks associated with CO 2 plume breakthrough.« less

Multimillion-Year Evolution of a Sublacustrine Fan System: Source-to-Sink History of the South Rukuru and Ruhuhu River Drainages, Lake Malawi (Nyasa) Rift, East Africa

NASA Astrophysics Data System (ADS)

Scholz, C. A.; Shillington, D. J.; McCartney, T.

2017-12-01

The development of long-lived continental rifts can be markedly influenced by surface processes, including sediment input and footwall erosion. This occurs through modifying crustal thickness and loading, as well as by influencing behaviors of individual faults. Here we report on the evolution of a long-lived system of sublacustrine fans in the Central Basin of the Lake Malawi (Nyasa) rift, East Africa. An extensive suite of crustal-scale seismic reflection data was acquired in 2015 as part of the SEGMeNT project, which resulted superb images of the syn-rift section. These data are augmented by legacy single-channel high resolution reflection data that provide detailed information on facies geometries and stacking architecture of the deep-water fan systems. The ages and lithologic character of the stratal surfaces observed in the reflection seismic data are constrained by ties to the 2005 scientific drill cores acquired during the Lake Malawi Scientific Drilling Project. The South Rukuru River is an eastward flowing regional drainage (11,900 km2) that enters Lake Malawi through an incision in the western border fault of the rift's Central Basin. The Rukuru River drainage (17,230 km2) enters the eastern side of the lake at an accommodation zone margin between the North and Central Basins. Both are antecedent drainages that prior to rifting may have delivered sediments to the Indian Ocean continental margin. Both systems now deliver sediment to a highly confined and focused depocenter in the Central Basin. The complex interplay of extension, mainly on the border fault systems, and high-frequency and high-amplitude lake levels shifts, has led to unique coarse sediment facies stacking architectures, with vertical stacking controlled by hydroclimate, and lateral positioning localized by fault behavior. Focused deep-water (700 m) deposition has resulted in overpressure within the sedimentary section in the localized depocenter, producing dramatic mud diapirs. Long-lived channel-levee systems observed in the seismic data demonstrate that both drainages systems have been operative for the past several million years.

Advancing Understanding of Earthquakes by Drilling an Eroding Convergent Margin

NASA Astrophysics Data System (ADS)

von Huene, R.; Vannucchi, P.; Ranero, C. R.

2010-12-01

A program of IODP with great societal relevance is sampling and instrumenting the seismogenic zone. The zone generates great earthquakes that trigger tsunamis, and submarine slides thereby endangering coastal communities containing over sixty percent of the earth’s population. To asses and mitigate this endangerment it is urgent to advance understanding of fault dynamics that allows more timely anticipation of hazardous seismicity. Seismogenesis on accreting and eroding convergent plate boundaries apparently differ because of dissimilar materials along the interplate fault. As the history of instrumentally recorded earthquakes expands the difference becomes clearer. The more homogeneous clay, silt and sand subducted at accreting margins is associated with great earthquakes (M 9) whereas the fragmented upper plate rock that can dominate subducted material along an eroding margin plate interface is associated with many tsunamigenic earthquakes (Bilek, 2010). Few areas have been identified where the seismogenic zone can be reached with scientific drilling. In IODP accreting margins are studied on the NanTroSeize drill transect off Japan where the ultimate drilling of the seismogenic interface may occur by the end of IODP. The eroding Costa Rica margin will be studied in CRISP where a drill program will begin in 2011. The Costa Rican geophysical site survey will be complete with acquisition and processing of 3D seismic data in 2011 but the entire drilling will not be accomplished in IODP. It is appropriate that the accreting margin study be accomplished soon considering the indications of a pending great earthquake that will affect a country that has devoted enormous resources to IODP. However, understanding the erosional end-member is scientifically as important to an understanding of fault mechanics. Transoceanic tsunamis affect the entire Pacific rim where most subduction zones are eroding margins. The Costa Rican subduction zone is less complex operationally and perhaps geologically than the Nankai margin. The developing Central American countries do not have the resources to contribute to IODP but this should not deter acquiring the scientific insights proposed in CRISP considering the broader scientific benefits. Such benefits include the first sampling and instrumentation of an actively eroding plate interface and drilling near or into an earthquake asperity. Drilling an eroding margin should significantly advance understanding of subduction zone fault mechanisms and help improve assessment of future hazardous earthquakes and tsunamis.

Internal Structure of Taiwan Chelungpu Fault Zone Gouges

NASA Astrophysics Data System (ADS)

Song, Y.; Song, S.; Tang, M.; Chen, F.; Chen, Y.

2005-12-01

Gouge formation is found to exist in brittle faults at all scale (1). This fine-grain gouge is thought to control earthquake instability. And thus investigating the gouge textures and compositions is very important to an understanding of the earthquake process. Employing the transmission electron microscope (TEM) and a new transmission X-ray microscope (TXM), we study the internal structure of fault zone gouges from the cores of the Taiwan Chelungpu-fault Drilling Project (TCDP), which drilled in the fault zone of 1999 Chi-Chi earthquake. This X-ray microscope have installed at beamline BL01B of the Taiwan Light Source, National Synchrotron Radiation Research Center (NSRRC). It provides 2D imaging and 3D tomography at energy 8-11 keV with a spatial resolution of 25-60 nm, and is equipped with the Zernike-phase contrast capability for imaging light materials. In this work, we show the measurements of gouge texture, particle size distribution and 3D structure of the ultracataclasite in fault gouges within 12 cm about 1111.29 m depth. These characterizations in transition from the fault core to damage zone are related to the comminuting and the fracture energy in the earthquake faulting. The TXM data recently shows the particle size distributions of the ultracataclasite are between 150 nm and 900 nm in diameter. We will keep analyzing the characterization of particle size distribution, porosity and 3D structure of the fault zone gouges in transition from the fault core to damage zone to realize the comminuting and fracture surface energy in the earthquake faulting(2-5).The results may ascertain the implication of the nucleation, growth, transition, structure and permeability of the fault zones(6-8). Furthermore, it may be possible to infer the mechanism of faulting, the physical and chemical property of the fault, and the nucleation of the earthquake. References 1) B. Wilson, T. Dewerw, Z. Reches and J. Brune, Nature, 434 (2005) 749. 2) S. E. Schulz and J. P. Evans, Tectonophysics 295 (1998) 223. 3) A. M. Boullier, K. Fujimoto, T. Ohtani, G. Roman-Ross, ? Lewin and H. Ito, P. Pezard, B. Ildefonse, Tectonophysics 378 (2004)v165. 4) Z. K. Shipton and P. A. Cowie, J. Structural Geology 25 (2003) 333. 5) J. S. Chester, F. M. Chester and A. K. Kronenberg, Nature 437, (2005) 133. 6) A. Billi, F. Salvini and F. Storti, J. Structural Geology 25 (2003)1779. 7) J. S. Caine, J. P. Evans and C. B. Forster, Geology 24 (11) (1996)1025. 8) N. Nakimura, T. Hirose and G. J. Borradaile, Earth and Planetary Science Letters 201 (2002) 13.

Seismic anisotropy in the vicinity of the Alpine fault, New Zealand, estimated by seismic interferometry

NASA Astrophysics Data System (ADS)

Takagi, R.; Okada, T.; Yoshida, K.; Townend, J.; Boese, C. M.; Baratin, L. M.; Chamberlain, C. J.; Savage, M. K.

2016-12-01

We estimate shear wave velocity anisotropy in shallow crust near the Alpine fault using seismic interferometry of borehole vertical arrays. We utilized four borehole observations: two sensors are deployed in two boreholes of the Deep Fault Drilling Project in the hanging wall side, and the other two sites are located in the footwall side. Surface sensors deployed just above each borehole are used to make vertical arrays. Crosscorrelating rotated horizontal seismograms observed by the borehole and surface sensors, we extracted polarized shear waves propagating from the bottom to the surface of each borehole. The extracted shear waves show polarization angle dependence of travel time, indicating shear wave anisotropy between the two sensors. In the hanging wall side, the estimated fast shear wave directions are parallel to the Alpine fault. Strong anisotropy of 20% is observed at the site within 100 m from the Alpine fault. The hanging wall consists of mylonite and schist characterized by fault parallel foliation. In addition, an acoustic borehole imaging reveals fractures parallel to the Alpine fault. The fault parallel anisotropy suggest structural anisotropy is predominant in the hanging wall, demonstrating consistency of geological and seismological observations. In the footwall side, on the other hand, the angle between the fast direction and the strike of the Alpine fault is 33-40 degrees. Since the footwall is composed of granitoid that may not have planar structure, stress induced anisotropy is possibly predominant. The direction of maximum horizontal stress (SHmax) estimated by focal mechanisms of regional earthquakes is 55 degrees of the Alpine fault. Possible interpretation of the difference between the fast direction and SHmax direction is depth rotation of stress field near the Alpine fault. Similar depth rotation of stress field is also observed in the SAFOD borehole at the San Andreas fault.

Gravity and magnetic data across the Ghost Dance Fault in WT-2 Wash, Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliver, H.W.; Sikora, R.F.

1994-12-31

Detailed gravity and ground magnetic data were obtained in September 1993 along a 4,650 ft-long profile across the Ghost Dance Fault system in WT-2 Wash. Gravity stations were established every 150 feet along the profile. Total-field magnetic measurements made initially every 50 ft along the profile, then remade every 20 ft through the fault zone. These new data are part of a geologic and geophysical study of the Ghost Dance Fault (GDF) which includes detailed geologic mapping, seismic reflection, and some drilling including geologic and geophysical logging. The Ghost Dance Fault is the only through-going fault that has been identifiedmore » within the potential repository for high-level radioactive waste at Yucca Mountain, Nevada. Preliminary gravity results show a distinct decrease of 0.1 to 0.2 mGal over a 600-ft-wide zone to the east of and including the mapped fault. The gravity decrease probably marks a zone of brecciation. Another fault-offset located about 2,000 ft to the east of the GDF was detected by seismic reflection data and is also marked by a distinct gravity low. The ground magnetic data show a 200-ft-wide magnetic low of about 400 nT centered about 100 ft east of the Ghost Dance Fault. The magnetic low probably marks a zone of brecciation within the normally polarized Topopah Spring Tuff, the top of which is about 170 ft below the surface, and which is known from drilling to extend to a depth of about 1,700 ft. Three-component magnetometer logging in drill hole WT-2 located about 2,700 ft east of the Ghost Dance Fault shows that the Topopah Spring Tuff is strongly polarized magnetically in this area, so that fault brecciation of a vertical zone within the Tuff could provide an average negative magnetic contrast of the 4 Am{sup {minus}1} needed to produce the 400 nT low observed at the surface.« less

What is an Oceanic Core Complex?

NASA Astrophysics Data System (ADS)

Schroeder, T.; Cheadle, M. J.

2007-12-01

The Mid-Atlantic Ridge (MAR) 75km north and south of the 15-20 Fracture Zone (FZ) has produced upper oceanic lithosphere composed dominantly of mantle peridotite with gabbro intrusions. In the absence of diapirism, mantle peridotite can only be exposed on the seafloor by extensional faulting, thus the sea floor geology and bathymetry provide widespread evidence for extensive low-angle faulting. However, only 3% of the seafloor in this region has the domal morphology characteristic of features that have been termed oceanic core complexes; suggesting that other processes, in addition to low-angle faulting, are responsible for the generation of domal core complexes. Most low-angle faults near the 15-20 FZ form gently dipping (10-15°), 10-15km-wide dip slopes on the flanks of 2000m relief bathymetric ridges that are up to 15-40km long (parallel to the MAR). Core recovered from ODP Leg 209 drill holes in these ridges is dominantly peridotite with small (<50m thick) gabbro intrusions. The peridotite is cut by a very high density of brittle faults dipping at both steep and gentle angles. Several holes also contain long-lived shear zones/faults in their upper reaches in which strain was localized at granulite facies, indicated by mylonitic olivine and cpx, and remained active during cooling to sub-greenschist grade, indicated by cross-cutting of progressively lower-grade syn-deformation mineral assemblages. These observations suggest that seafloor spreading is largely accommodated here by slip on low-angle faults, and that these faults are correctly termed detachment faults. Holes drilled into a domal oceanic core complex north of the 15-20 FZ during Leg 209 (ODP Site 1275) recovered dominantly gabbro and not mantle peridotite. This hole is cut by significantly fewer brittle and ductile faults than the peridotite drilled at the non-core-complex detachment fault sites. The detachment fault in the upper reaches (50m) of Site 1275 was localized at temperatures near feldspar's ductile-to-brittle transition, indicated by cataclasis with minor crystal plastic flow in plagioclase, and a lack of pervasive pure-ductile deformation. Amphibole-plagioclase thermometry in the fault yields equilibrium temperatures from 600-650°C, compared to equilibrium temperatures of 750-850°C for the gabbro outside the fault. The presence of talc- chlorite schists and cataclasites cutting the higher-temperature deformation textures indicate fault activity down- temperature from amphibolite through greenschist facies. This core-complex-bounding fault contrasts with the fault that bounds the Atlantis Bank Core Complex on the Southwest Indian Ridge (SWIR). There, the fault is 100m thick and strain was initially localized at granulite grade (>800°C) (Mehl & Hirth, 2007); significantly hotter than the Site 1275 fault. Therefore, the formation of core-complex morphology does not seem to depend on the initial faulting conditions. Both oceanic core complexes that have been drilled besides Site 1275, Atlantis Massif at 30°N (IODP Hole 1309D) on the MAR and Atlantis Bank on the SWIR (ODP Hole 735B), are also comprised dominantly of gabbro. This suggests that magma supply may be an essential requirement for core complex formation and raises the question whether all domal oceanic core complexes are cored by gabbro? We also ask whether the term 'oceanic core complex' should be restricted to these domal features and not applied to detachment-bound, non- domal, peridotite-cored ridges; or if these should be considered two sub-classes of oceanic core complexes.

Numerical modeling of regional stress distributions for geothermal exploration

NASA Astrophysics Data System (ADS)

Guillon, Theophile; Peter-Borie, Mariane; Gentier, Sylvie; Blaisonneau, Arnold

2017-04-01

Any high-enthalpy unconventional geothermal projectcan be jeopardized by the uncertainty on the presence of the geothermal resource at depth. Indeed, for the majority of such projects the geothermal resource is deeply seated and, with the drilling costs increasing accordingly, must be located as precisely as possible to increase the chance of their economic viability. In order to reduce the "geological risk", i.e., the chance to poorly locate the geothermal resource, a maximum amount of information must be gathered prior to any drilling of exploration and/or operational well. Cross-interpretation from multiple disciplines (e.g., geophysics, hydrology, geomechanics …) should improve locating the geothermal resource and so the position of exploration wells ; this is the objective of the European project IMAGE (grant agreement No. 608553), under which the work presented here was carried out. As far as geomechanics is concerned, in situ stresses can have a great impact on the presence of a geothermal resource since they condition both the regime within the rock mass, and the state of the major fault zones (and hence, the possible flow paths). In this work, we propose a geomechanical model to assess the stress distribution at the regional scale (characteristic length of 100 kilometers). Since they have a substantial impact on the stress distributions and on the possible creation of regional flow paths, the major fault zones are explicitly taken into account. The Distinct Element Method is used, where the medium is modeled as fully deformable blocks representing the rock mass interacting through mechanically active joints depicting the fault zones. The first step of the study is to build the model geometry based on geological and geophysical evidences. Geophysical and structural geology results help positioning the major fault zones in the first place. Then, outcrop observations, structural models and site-specific geological knowledge give information on the fault zones family sets and their priority rule. In the second step, the physical model must be established, including constitutive equations for the rock mass and the fault zones, initial state and boundary conditions. At such large scales, physical laws and parameters are difficult to assess and must be constrained by sensitivity analysis. In the last step of the study, the results can be interpreted to highlight areas where the mechanical conditions favor the presence of a geothermal resource. The DEM enables accounting for the strong stress redistributions inherent to highly-segmented geometries, and to the dilational opening of fault zones under shearing. A 130x150 square-kilometers region within the Upper Rhine Graben is used as a case-study to illustrate the building and interpretation of a regional stress model.

Initial results from the Nankai Trough shallow splay and frontal thrust (IODP Expedition 316): Implications for fluid flow

NASA Astrophysics Data System (ADS)

Screaton, E.; Kimura, G.; Curewitz, D.; Scientists, E.

2008-12-01

Integrated Ocean Drilling Program (IODP) Expedition 316 examined the frontal thrust and the shallow portion of the megasplay fault offshore of the Kii peninsula, and was the third drilling expedition of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). NanTroSEIZE will integrate seafloor observations, drilling, and observatories to investigate the processes controlling slip along subduction zone plate boundary fault systems. Site C0004 examined a shallow portion of the splay fault system where it overrides slope basin sediments. Site C0008, located in the slope basin 1 km seaward of Site C0004, provided a reference site for the footwall sediments. Results of drilling indicate that the footwall sediments have dewatered significantly, suggesting permeable routes for fluid escape. These high-permeability pathways might be provided by coarse-grained layers within the slope sediments. In situ dewatering and multiple fluid escape paths will tend to obscure any geochemical signature of flow from depth. Sites C0006 and C0007 examined the frontal thrust system. Although poorly recovered, coarse-grained trench sediments were sampled within the footwall. These permeable sediments would be expected to allow rapid escape of any fluid pressures due to loading. At both sites, low porosities are observed at shallow depths, suggesting removal of overlying material. This observation is consistent with interpretations that the prism is unstable and currently in a period of collapse. Anomalously low temperatures were measured within boreholes at these sites. One possible explanation for the low temperatures is circulation of seawater along normal faults in the unstable prism.

Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture-Mediated Fluid and Heat Transport in the Alpine Fault's Hanging-Wall Damage Zone

NASA Astrophysics Data System (ADS)

Townend, John; Sutherland, Rupert; Toy, Virginia G.; Doan, Mai-Linh; Célérier, Bernard; Massiot, Cécile; Coussens, Jamie; Jeppson, Tamara; Janku-Capova, Lucie; Remaud, Léa.; Upton, Phaedra; Schmitt, Douglas R.; Pezard, Philippe; Williams, Jack; Allen, Michael John; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin M.; Boulton, Carolyn; Broderick, Neil; Carpenter, Brett; Chamberlain, Calum J.; Cooper, Alan; Coutts, Ashley; Cox, Simon C.; Craw, Lisa; Eccles, Jennifer D.; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Henry, Gilles; Howarth, Jamie; Jacobs, Katrina; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Tim; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luis; Mori, Hiroshi; Niemeijer, André; Nishikawa, Osamu; Nitsch, Olivier; Paris, Jehanne; Prior, David J.; Sauer, Katrina; Savage, Martha K.; Schleicher, Anja; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Zimmer, Martin

2017-12-01

Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging-wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP-2). We present observational evidence for extensive fracturing and high hanging-wall hydraulic conductivity (˜10-9 to 10-7 m/s, corresponding to permeability of ˜10-16 to 10-14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP-2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging-wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off-fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation.

Testing the Extensional Detachment Paradigm: A Borehole Observatory in the Sevier Desert Basin, Utah

NASA Astrophysics Data System (ADS)

Christie-Blick, N.; Wernicke, B. P.

2007-12-01

The Sevier Desert basin, Utah represents a world-class target for scientific drilling and for the development of an in situ borehole observatory of active faulting, with potential for establishing that normal-sense slip can occur along a brittle low-angle fault and, by determining the conditions under which that may take place, for resolving the mechanical paradox associated with such structures. The Sevier Desert detachment was defined in the mid- 1970s on the basis seismic reflection data and commercial wells as the contact between Paleozoic carbonate rocks and Cenozoic basin fill over a depth range of ~0-4 km. Today, the interpreted fault is thought by most workers to root into the crust to the west, to have large estimated offset (< 47 km), to have been active over most of its history near its present 11° dip, and to be associated with contemporary surface extension (a 30- km-long zone of prominent Holocene fault scarps immediately west of Clear Lake). Although no seismicity has been documented on the detachment, its scale is consistent with earthquake magnitudes as large as M 7.0. A published alternative interpretation of the Paleozoic-Cenozoic contact as an unconformity rather than a fault has not been generally accepted. Deformation at detachment faults is commonly spatially restricted, and may have been missed in well cuttings. Exhumation of the detachment would have made it possible to remove critical footwall evidence prior to later sedimentary onlap, particularly at updip locations. The incomplete coverage and uneven quality of seismic reflection data on which the detachment interpretation depends, and an unresolved debate about stratigraphic ties to a critical well, leave room for discussion about interpretive details, including the possibility that deformation was distributed across several closely spaced faults. An apparent mismatch between stratigraphically based ages and fission-track evidence for the timing of footwall exhumation cannot be resolved with available well data. Drilling is now needed to make in situ measurements at depth, to obtain critical core of fault rocks at a down-dip site where offset should be large, and to establish more clearly the relationship between basin development and displacement along the interpreted fault. A workshop will take place from July 15-18, 2008, in Utah, under the auspices of the International Continental Scientific Drilling Program, to flesh out objectives, strategies and operational details, and to develop a consensus on the location of a drill site.

3D imaging of geological structures by R-VSP utilizing vibrations caused by shaft excavations at the Mizunami Underground Research Laboratory in Japan

NASA Astrophysics Data System (ADS)

Matsuoka, T.; Hodotsuka, Y.; Ishigaki, K.; Lee, C.

2009-12-01

Japan Atomic Energy Agency is now conducting the Mizunami Underground Research Laboratory (MIU) project. The MIU consists of two shafts (main shaft: 6.5m, ventilation shaft: 4.5m diameter) and horizontal research galleries, in sedimentary and granitic rocks at Mizunami City, Central Japan. The MIU project is a broad scientific study of the deep geological environment providing the basis for research and development for geological disposal of high level radioactive waste. One of the main goals is to establish techniques for investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. As a part of the MIU project, we carried out the Reverse-Vertical Seismic Profile (R-VSP) using vibrations from the blasting for the shaft excavations and drilling of boreholes in the horizontal research galleries and examined the applicability of this method to imaging of geological structures around underground facilities, such as the unconformity between the sedimentary rocks and the basal granite, and faults and fracture zones in the granite. R-VSP method is a seismic method utilizing the receiver arrays on surface and seismic sources underground (e.g. in boreholes). This method is advantageous in that planning of 3-dimensional surveys is easy compared with reflection seismic surveying and conventional VSP because seismic source arrays that are major constraint for conducting surveys on surface are unnecessary. The receiver arrays consist of six radial lines on surface with a central focus on the main shaft. Seven blast rounds for the main shaft excavation from GL-52.8m to GL-250m and the borehole drilling in the GL-200m horizontal research gallery were observed. Three types of data processing, conventional VSP data processing (VSP-CDP transform and VSP migration), Reflection data processing utilizing Seismic interferometry method (“Seismic interferometry”) and Reflection mapping utilizing Image Point transform method (“IP transform”), were performed to obtain reflection images from heterogeneous geological structure. As the results, the reflective events that seemed to correspond with sedimentary layers, the unconformity between sedimentary rocks and granite, and fracture zones in granite could be detected by reflection profiles using “conventional VSP data processing” and “Seismic interferometry”. However, it is difficult to identify the faults around the MIU because they are generally at a high-angle. “IP transform” is one type of Radon transform which change common shot gather to IP domain. Image Points are defined through geometries of sources and reflectors. Reflection signals in time domain can be accumulated and enhanced in IP domain by “IP transform” on the condition of the right angle to a fault. So, by a search of the direction that reflection signals are enhanced using “IP transform”, the locations of faults can be inferred. By this method, the distribution of faults that correspond with faults in the current geological model constructed from investigation data in the MIU project could be detected.

Drilling into a present-day migration pathway for hydrocarbons within a fault zone conduit in the Eugene Island 330 field, offshore Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, R.N.

1995-11-01

Within the Global Basins Research Network, we have developed 4-D seismic analysis techniques that, when integrated with pressure and temperature mapping, production history, geochemical monitoring, and finite element modeling, allow for the imaging of active fluid migration in the subsurface. We have imaged fluid flow pathways that are actively recharging shallower hydrocarbon reservoirs in the Eugene Island 330 field, offshore Louisiana. The hydrocarbons appear to be sourcing from turbidite stacks within the salt-withdrawal mini-basin buried deep within geopressure. Fault zone conduits provide transient migration pathways out of geopressure. To accomplish this 4-D imaging, we use multiple 3-D seismic surveys donemore » several years apart over the same blocks. 3-D volume processing and attribute analysis algorithms are used to identify significant seismic amplitude interconnectivity and changes over time that result from active fluid migration. Pressures and temperatures are then mapped and modeled to pro- vide rate and timing constraints for the fluid movement. Geochemical variability observed in the shallow reservoirs is attributed to the mixing of new with old oils. The Department of Energy has funded an industry cost-sharing project to drill into one of these active conduits in Eugene Island Block 330. Active fluid flow was encountered within the fault zone in the field demonstration experiment, and hydrocarbons were recovered. The active migration events connecting shallow reservoirs to deep sourcing regions imply that large, heretofore undiscovered hydrocarbon reserves exist deep within geopressures along the deep continental shelf of the northern Gulf of Mexico.« less

Tectonics and geology of spreading ridge subduction at the Chile Triple Junction: a synthesis of results from Leg 141 of the Ocean Drilling Program

USGS Publications Warehouse

Behrmann, J.H.; Lewis, S.D.; Cande, S.C.

1994-01-01

An active oceanic spreading ridge is being subducted beneath the South American continent at the Chile Triple Junction. This process has played a major part in the evolution of most of the continental margins that border the Pacific Ocean basin. A combination of high resolution swath bathymetric maps, seismic reflection profiles and drillhole and core data from five sites drilled during Ocean Drilling Program (ODP) Leg 141 provide important data that define the tectonic, structural and stratigraphic effects of this modern example of spreading ridge subduction. A change from subduction accretion to subduction erosion occurs along-strike of the South American forearc. This change is prominently expressed by normal faulting, forearc subsidence, oversteepening of topographic slopes and intensive sedimentary mass wasting, overprinted on older signatures of sediment accretion, overthrusting and uplift processes in the forearc. Data from drill sites north of the triple junction (Sites 859-861) show that after an important phase of forearc building in the early to late Pliocene, subduction accretion had ceased in the late Pliocene. Since that time sediment on the downgoing oceanic Nazca plate has been subducted. Site 863 was drilled into the forearc in the immediate vicinity of the triple junction above the subducted spreading ridge axis. Here, thick and intensely folded and faulted trench slope sediments of Pleistocene age are currently involved in the frontal deformation of the forearc. Early faults with thrust and reverse kinematics are overprinted by later normal faults. The Chile Triple Junction is also the site of apparent ophiolite emplacement into the South American forearc. Drilling at Site 862 on the Taitao Ridge revealed an offshore volcanic sequence of Plio-Pleistocene age associated with the Taitao Fracture Zone, adjacent to exposures of the Pliocene-aged Taitao ophiolite onshore. Despite the large-scale loss of material from the forearc at the triple junction, ophiolite emplacement produces a large topographic promontory in the forearc immediately after ridge subduction, and represents the first stage of forearc rebuilding. ?? 1994 Springer-Verlag.

3D Groundwater flow model at the Upper Rhine Graben scale to delineate preferential target areas for geothermal projects

NASA Astrophysics Data System (ADS)

Armandine Les Landes, Antoine; Guillon, Théophile; Peter-Borie, Mariane; Rachez, Xavier

2017-04-01

Any deep unconventional geothermal project remains risky because of the uncertainty regarding the presence of the geothermal resource at depth and the drilling costs increasing accordingly. That's why this resource must be located as precisely as possible to increase the chances of successful projects and their economic viability. To minimize the risk, as much information as possible should be gathered prior to any drilling. Usually, the position of the exploration wells of geothermal energy systems is chosen based on structural geology observations, geophysics measurements and geochemical analyses. Confronting these observations to results from additional disciplines should bring more objectivity in locating the region to explore and where to implant the geothermal system. The Upper Rhine Graben (URG) is a tectonically active rift system that corresponds to one branch of the European Cenozoic Rift System where the basin hosts a significant potential for geothermal energy. The large fault network inherited from a complex tectonic history and settled under the sedimentary deposits hosts fluid circulation patterns. Geothermal anomalies are strongly influenced by fluid circulations within permeable structures such as fault zones. In order to better predict the location of the geothermal resource, it is necessary to understand how it is influenced by heat transport mechanisms such as groundwater flow. The understanding of fluid circulation in hot fractured media at large scale can help in the identification of preferential zones at a finer scale where additional exploration can be carried out. Numerical simulations is a useful tool to deal with the issue of fluid circulations through large fault networks that enable the uplift of deep and hot fluids. Therefore, we build a numerical model to study groundwater flow at the URG scale (150 x 130km), which aims to delineate preferential zones. The numerical model is based on a hybrid method using a Discrete Fracture Network (DFN) and 3D elements to simulate groundwater flow in the 3D regional fault network and in sedimentary deposits, respectively. Firstly, the geometry of the 3D fracture network and its hydraulic connections with 3D elements (sedimentary cover) is built in accordance with the tectonic history and based on geological and geophysical evidences. Secondly, data from previous studies and site-specific geological knowledge provide information on the fault zones family sets and on respective hydraulic properties. Then, from the simulated 3D groundwater flow model and based on a particle tracking methodology, groundwater flow paths are constructed. The regional groundwater flow paths results are extracted and analysed to delineate preferential zones to explore at finer scale and so to define the potential positions of the exploration wells. This work is conducted in the framework of the IMAGE project (Integrated Methods for Advanced Geothermal Exploration, grant agreement No. 608553), which aims to develop new methods for better siting of exploitation wells.

Preliminary Studies of the Structural Characteristics of the Lubao Fault using 2D High Resolution Shallow Seismic Reflection Profile

NASA Astrophysics Data System (ADS)

Bonus, A. A. B.; Lagmay, A. M. A.; Rodolfo, K. S.

2016-12-01

The Lubao fault, located in the province of Pampanga, Philippines, is part of the Bataan Volcanic Arc Complex (BVAC). Active faults within and around the BVAC include the East Zambales and Iba faults; according to the official active faults map of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) there are no other existing active faults in the area. The Lubao Fault distinctly separates wetlands to the northeast and dry alluvial plains to the northwest of Manila Bay. Long term subsidence and high sedimentation rates were observed in the fault and over the past 1.5 thousand years, the northeastern block has dropped 3.5 meters. Along the southwest flank of Mount Natib, tectonic structures were identified using surface mapping and remote sensing. The Persistent Scattering Interferometric Synthetic Aperture Radar (PSInSAR) data results of Eco et al. in 2015 shows uplifts and subsidence in the BVAC area delineating the Lubao Fault. A 480-meter seismic reflection line was laid down perpendicular to the fault with a recording system consisting of 48 channels of Geometrics geophones spaced 10 meters apart. Acquired data were processed using the standard seismic reflection processing sequence by Yilmaz 2001. This preliminary study produced a high resolution subsurface profile of the Lubao fault in the village of San Rafael, Lubao where it is well manifested. The velocity model integrated by stratigraphic data of drilled core shows subsurface lithology. The depth converted profile reveals clear structures and dipping segments which indicates a history of movement along the Lubao fault. Discontinuity of reflectors, either offsets or breaks, are considered structures along the subsurface of the study area. Additional structural mapping and seismic lines along the projected fault are planned in the future to further detail the characteristics of the Lubao Fault. The surface observations made by other researchers coupled with the subsurface seismic profile mapping of this study hopes to clearly delineate and characterize the Lubao Fault.

Fracture Modes and Identification of Fault Zones in Wenchuan Earthquake Fault Scientific Drilling Boreholes

NASA Astrophysics Data System (ADS)

Deng, C.; Pan, H.; Zhao, P.; Qin, R.; Peng, L.

2017-12-01

After suffering from the disaster of Wenchuan earthquake on May 12th, 2008, scientists are eager to figure out the structure of formation, the geodynamic processes of faults and the mechanism of earthquake in Wenchuan by drilling five holes into the Yingxiu-Beichuan fault zone and Anxian-Guanxian fault zone. Fractures identification and in-situ stress determination can provide abundant information for formation evaluation and earthquake study. This study describe all the fracture modes in the five boreholes on the basis of cores and image logs, and summarize the response characteristics of fractures in conventional logs. The results indicate that the WFSD boreholes encounter enormous fractures, including natural fractures and induced fractures, and high dip-angle conductive fractures are the most common fractures. The maximum horizontal stress trends along the borehole are deduced as NWW-SEE according to orientations of borehole breakouts and drilling-induced fractures, which is nearly parallel to the strikes of the younger natural fracture sets. Minor positive deviations of AC (acoustic log) and negative deviation of DEN (density log) demonstrate their responses to fracture, followed by CNL (neutron log), resistivity logs and GR (gamma ray log) at different extent of intensity. Besides, considering the fact that the reliable methods for identifying fracture zone, like seismic, core recovery and image logs, can often be hampered by their high cost and limited application, this study propose a method by using conventional logs, which are low-cost and available in even old wells. We employ wavelet decomposition to extract the high frequency information of conventional logs and reconstruction a new log in special format of enhance fracture responses and eliminate nonfracture influence. Results reveal that the new log shows obvious deviations in fault zones, which confirm the potential of conventional logs in fracture zone identification.

Characteristics of crushed rocks observed in drilled cores in landslide bodies located in accretionary complexes

NASA Astrophysics Data System (ADS)

Wakizaka, Yasuhiko

2013-10-01

The recent development of high-quality boring, which uses foam surfactants, has made it possible to examine the detailed geological constitution and structure of landslide bodies. However, geological information related to landslides has not been obtained appropriately even from undisturbed high-quality drilled cores. Moreover, it has been difficult to distinguish between rocks crushed by landslide movement and the fault breccia in accretionary complexes. We examined the detailed geology of high-quality drilled cores of landslide bodies on the Shimanto Belt and the Chichibu Belt. The fault breccia near the landslide bodies was found to exhibit planar fabrics while the crushed breccias in the landslide bodies showed a random fabric. We discovered that classifying the degree of crushing and inspecting the planar fabrics of rocks are effective in the geological determination of landslide bodies.

Scientific drilling into the San Andreas Fault Zone - an overview of SAFOD's first five years

USGS Publications Warehouse

Zoback, Mark; Hickman, Stephen; Ellsworth, William; ,

2011-01-01

The San Andreas Fault Observatory at Depth (SAFOD) was drilled to study the physical and chemical processes controlling faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD is located near Parkfield, California and penetrates a section of the fault that is moving due to a combination of repeating microearthquakes and fault creep. Geophysical logs define the San Andreas Fault Zone to be relatively broad (~200 m), containing several discrete zones only 2–3 m wide that exhibit very low P- and S-wave velocities and low resistivity. Two of these zones have progressively deformed the cemented casing at measured depths of 3192 m and 3302 m. Cores from both deforming zones contain a pervasively sheared, cohesionless, foliated fault gouge that coincides with casing deformation and explains the observed extremely low seismic velocities and resistivity. These cores are being now extensively tested in laboratories around the world, and their composition, deformation mechanisms, physical properties, and rheological behavior are studied. Downhole measurements show that within 200 m (maximum) of the active fault trace, the direction of maximum horizontal stress remains at a high angle to the San Andreas Fault, consistent with other measurements. The results from the SAFOD Main Hole, together with the stress state determined in the Pilot Hole, are consistent with a strong crust/weak fault model of the San Andreas. Seismic instrumentation has been deployed to study physics of faulting—earthquake nucleation, propagation, and arrest—in order to test how laboratory-derived concepts scale up to earthquakes occurring in nature.

Changes in paleostress and its magnitude related to seismic cycles in the Chelung-pu Fault, Taiwan

NASA Astrophysics Data System (ADS)

Hashimoto, Yoshitaka; Tobe, Kota; Yeh, En-Chao; Lin, Weiren; Song, Sheng-Rong

2015-12-01

Paleostress analysis was conducted through a multiple stress inversion method using slip data recoded for the core samples from the Taiwan Chelung-pu Fault Drilling Project (TCDP). Two stress fields were obtained; one of these had horizontally plunging σ1, and the other has horizontally plunging σ2 or σ3 in the compressional stress direction of the Chi-Chi earthquake. Stress magnitude for both the stress fields was constrained by stress polygons, which indicated larger SHmax for horizontally plunging σ1 than that in the case of horizontally plunging σ2 or σ3. These differences in stress orientations and stress magnitude suggest that the change in stress filed can be caused by stress drop and stress buildup associated with seismic cycles. The seismic cycles recoded in the core samples from TCDP could include many events at geological timescale and not only the 1999 Chi-Chi earthquake.

Role of Geomechanics in Assessing the Feasibility of CO2 Sequestration in Depleted Hydrocarbon Sandstone Reservoirs

NASA Astrophysics Data System (ADS)

Fang, Zhi; Khaksar, Abbas

2013-05-01

Carbon dioxide (CO2) sequestration in depleted sandstone hydrocarbon reservoirs could be complicated by a number of geomechanical problems associated with well drilling, completions, and CO2 injection. The initial production of hydrocarbons (gas or oil) and the resulting pressure depletion as well as associated reduction in horizontal stresses (e.g., fracture gradient) narrow the operational drilling mud weight window, which could exacerbate wellbore instabilities while infill drilling. Well completions (casing, liners, etc.) may experience solids flowback to the injector wells when injection is interrupted due to CO2 supply or during required system maintenance. CO2 injection alters the pressure and temperature in the near wellbore region, which could cause fault reactivation or thermal fracturing. In addition, the injection pressure may exceed the maximum sustainable storage pressure, and cause fracturing and fault reactivation within the reservoirs or bounding formations. A systematic approach has been developed for geomechanical assessments for CO2 storage in depleted reservoirs. The approach requires a robust field geomechanical model with its components derived from drilling and production data as well as from wireline logs of historical wells. This approach is described in detail in this paper together with a recent study on a depleted gas field in the North Sea considered for CO2 sequestration. The particular case study shows that there is a limitation on maximum allowable well inclinations, 45° if aligning with the maximum horizontal stress direction and 65° if aligning with the minimum horizontal stress direction, beyond which wellbore failure would become critical while drilling. Evaluation of sanding risks indicates no sand control installations would be needed for injector wells. Fracturing and faulting assessments confirm that the fracturing pressure of caprock is significantly higher than the planned CO2 injection and storage pressures for an ideal case, in which the total field horizontal stresses increase with the reservoir re-pressurization in a manner opposite to their reduction with the reservoir depletion. However, as the most pessimistic case of assuming the total horizontal stresses staying the same over the CO2 injection, faulting could be reactivated on a fault with the least favorable geometry once the reservoir pressure reaches approximately 7.7 MPa. In addition, the initial CO2 injection could lead to a high risk that a fault with a cohesion of less than 5.1 MPa could be activated due to the significant effect of reduced temperature on the field stresses around the injection site.

Quantitative Characterisation of Fracturing Around the Damage Zone Surrounding New Zealand's Alpine Fault Using X-ray CT Scans of DFDP-1 Core

NASA Astrophysics Data System (ADS)

Williams, J. N.; Toy, V.; Massiot, C.; Mcnamara, D. D.; Wang, T.

2015-12-01

X-ray computer tomography (CT) scans of core recovered from the first phase of the Deep Fault Drilling Project (DFDP-1) through the Alpine Fault provide an excellent opportunity to analyse brittle deformation around the fault. In particular, assessment can be made of the heavily fractured protolith constituting the damage zone. Damage zone structures are divided into two types that result from two distinct processes: (1) "off fault damage" formed by stress changes induced by the passage of a seismic rupture and (2) "off fault deformation" that represent structures, which accommodate strain around the fault that was not localised on the principal slip zone (PSZ). The distribution of these damage zones structures within CT scans of the recovered core was measured along a scanline parallel to the core axis and assessed using a weighted moving average technique to account for orientation bias. The results of this analysis reveal that within the part of the fault rocks sampled by DFDP-1 there is no increase in density of these structures towards the PSZ. This is in agreement with independent analysis using Borehole Televiewer Data of the DFDP-1B borehole. Instead, we consider the density of these structures to be controlled to the first order by lithology, which modulates the mechanical properties of the fault rocks such as its frictional strength and cohesion. Comparisons of fracture density to p-wave velocities obtained from wireline logs indicate they are independent of each other, therefore, for the cores sampled in this study fractures impart no influence on the elastic properties of the rock. This is consistent with the observation from core that the majority of fractures are cemented. We consider how this might influence future rupture dynamics.

Large‐displacement, hydrothermal frictional properties of DFDP‐1 fault rocks, Alpine Fault, New Zealand: Implications for deep rupture propagation

PubMed Central

Boulton, C.; Toy, V. G.; Townend, J.; Sutherland, R.

2016-01-01

Abstract The Alpine Fault, New Zealand, is a major plate‐bounding fault that accommodates 65–75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP‐1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity‐strengthening behavior to velocity‐weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity‐weakening region restricted to higher velocity for higher temperatures. Friction was substantially lower for low‐velocity shearing (V < 0.3 µm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate‐and‐state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity‐strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle‐plastic transition for quartzofeldspathic compositions. PMID:27610290

Architecture of buried reverse fault zone in the sedimentary basin: A case study from the Hong-Che Fault Zone of the Junggar Basin

NASA Astrophysics Data System (ADS)

Liu, Yin; Wu, Kongyou; Wang, Xi; Liu, Bo; Guo, Jianxun; Du, Yannan

2017-12-01

It is widely accepted that the faults can act as the conduits or the barrier for oil and gas migration. Years of studies suggested that the internal architecture of a fault zone is complicated and composed of distinct components with different physical features, which can highly influence the migration of oil and gas along the fault. The field observation is the most useful methods of observing the fault zone architecture, however, in the petroleum exploration, what should be concerned is the buried faults in the sedimentary basin. Meanwhile, most of the studies put more attention on the strike-slip or normal faults, but the architecture of the reverse faults attracts less attention. In order to solve these questions, the Hong-Che Fault Zone in the northwest margin of the Junggar Basin, Xinjiang Province, is chosen for an example. Combining with the seismic data, well logs and drill core data, we put forward a comprehensive method to recognize the internal architectures of buried faults. High-precision seismic data reflect that the fault zone shows up as a disturbed seismic reflection belt. Four types of well logs, which are sensitive to the fractures, and a comprehensive discriminated parameter, named fault zone index are used in identifying the fault zone architecture. Drill core provides a direct way to identify different components of the fault zone, the fault core is composed of breccia, gouge, and serpentinized or foliated fault rocks and the damage zone develops multiphase of fractures, which are usually cemented. Based on the recognition results, we found that there is an obvious positive relationship between the width of the fault zone and the displacement, and the power-law relationship also exists between the width of the fault core and damage zone. The width of the damage zone in the hanging wall is not apparently larger than that in the footwall in the reverse fault, showing different characteristics with the normal fault. This study provides a comprehensive method in identifying the architecture of buried faults in the sedimentary basin and would be helpful in evaluating the fault sealing behavior.

Changes in In Situ Stress Across the Nankai and Cascadia Convergent Margins From Borehole Breakout Measurements During Ocean Drilling

NASA Astrophysics Data System (ADS)

McNeill, L.; Moore, J. C.; Yamada, Y.; Chang, C.; Tobin, H.; Kinoshita, M.; Gulick, S.; Moore, G.; Iodp Exp. 314/315/316 Science Party, &

2008-12-01

Borehole breakouts are commonly observed in borehole images shortly after drilling of continental margin sites. This study aims to compile and compare these results to determine what in situ shallow stress measurements can tell us about the larger scale tectonic regime. Recent Logging While Drilling resistivity images across the Kumano transect of the Nankai subduction zone, during Expedition 314, Stage 1 of the IODP NanTroSEIZE project, add to this dataset. Expedition 314 site data within the prism (C0001, C0004, C0006, including the megasplay fault system which may overlie the seismogenic updip limit) suggest maximum compressive stress (SHmax) is perpendicular to the margin (not parallel to the convergence vector) but is rotated through 90° at the forearc basin site (C0002). These results may point to changes in stress state of the shallow forearc from east to west: compression in the aseismic active prism (with evidence of strain partitioning of oblique convergence); and extension above the updip seismogenic zone suggesting focus of plate coupling at the plate boundary and not in the shallow forearc. Further south, ODP Leg 196 drilled the prism toe (808) with breakouts indicating SHmax parallel to the convergence vector, in contrast to Exp. 314 results. The stress state in the shallow prism at Site 808 may be affected by nearby seamount subduction or may represent differences in strain partitioning. On the Cascadia margin, two drilling legs have collected LWD borehole images (Leg 204 and Exp. 311). Leg 204 drilled 3 sites at hydrate ridge in the C Cascadia outer prism with breakout orientations variable between closely spaced sites. Prism fold axes are parallel to the margin so we might expect SHmax perpendicular to the margin as in Exp. 314. Deviations from this orientation may reflect local and surface effects (Goldberg and Janik, 2006). Exp. 311, N Cascadia, drilled 5 sites across the prism with breakouts in LWD images. Subduction is not oblique here, in contrast to the other sites discussed, and most sites indicate SHmax almost parallel to convergence and normal to major fold axes. In one case, the in situ stress orientation is also compatible with shallow normal faulting from seismic data. Site 1325, in a slope basin, deviates from this orientation and may reflect local processes. Borehole breakouts within the shallow forearc of convergent margins are often in agreement with other indications of regional tectonic stress and may be indicative of processes at depth. Deviations may represent local stresses due to gravitational processes.

Examination of the relationship between project management critical success factors and project success of oil and gas drilling projects

NASA Astrophysics Data System (ADS)

Alagba, Tonye J.

Oil and gas drilling projects are the primary means by which oil companies recover large volumes of commercially available hydrocarbons from deep reservoirs. These types of projects are complex in nature, involving management of multiple stakeholder interfaces, multidisciplinary personnel, complex contractor relationships, and turbulent environmental and market conditions, necessitating the application of proven project management best practices and critical success factors (CSFs) to achieve success. Although there is some practitioner oriented literature on project management CSFs for drilling projects, none of these is based on empirical evidence, from research. In addition, the literature has reported alarming rates of oil and gas drilling project failure, which is attributable not to technical factors, but to failure of project management. The aim of this quantitative correlational study therefore, was to discover an empirically verified list of project management CSFs, which consistent application leads to successful implementation of oil and gas drilling projects. The study collected survey data online, from a random sample of 127 oil and gas drilling personnel who were members of LinkedIn's online community "Drilling Supervisors, Managers, and Engineers". The results of the study indicated that 10 project management factors are individually related to project success of oil and gas drilling projects. These 10 CSFs are namely; Project mission, Top management support, Project schedule/plan, Client consultation, Personnel, Technical tasks, Client acceptance, Monitoring and feedback, Communication, and Troubleshooting. In addition, the study found that the relationships between the 10 CSFs and drilling project success is unaffected by participant and project demographics---role of project personnel, and project location. The significance of these findings are both practical, and theoretical. Practically, application of an empirically verified CSFs list to oil and gas drilling projects could help oil companies improve the performance of future drilling projects. Theoretically, the study's findings may help to bridge a gap in the project management CSFs literature, and add to the general project management body of knowledge.

Distribution of resistive and conductive structures in Nankai accretionary wedge reveals contrasting stress paths

NASA Astrophysics Data System (ADS)

Conin, Marianne; Bourlange, Sylvain; Henry, Pierre; Boiselet, Aurelien; Gaillot, Philippe

2014-01-01

In this article, we study the characteristics and spatial distribution of the deformation structures along the Kumano transect of the Nankai accretionary wedge, and use this information to interpret the stress path followed by the sediments. Deformation structures are identified from logging while drilling (LWD) resistivity images of the materials surrounding the drill hole and from 3-dimensional X-ray CT-images of cores acquired during the IODP NanTroSEIZE project. The relative resistivity of the structures identified on logs and the strike, dip, and density of structures identified on CT scan images are measured. The analysis of dip and strike of structures indicates that most of the resistive structures identified on logging data correspond to compactive shear bands. Results also indicate that conductive structures predominate at the toe of the prism and above the main out of sequence thrust, in locations where past and recent erosion occurred. We propose several mechanisms that could explain the relation between erosion and the absence of compactive shear bands. We conclude that sediments followed different stress paths depending on their location within the wedge, and that those differences explain the distribution of deformation structures within the wedge. We also show the coexistence of dilatant and compactant structures in fault zones including the frontal thrust and mega splay fault, and we interpret the coexistence of these structures as a possible consequence of a transient fluid pressure.

Earthquake sequence simulations with measured properties for JFAST core samples

NASA Astrophysics Data System (ADS)

Noda, Hiroyuki; Sawai, Michiyo; Shibazaki, Bunichiro

2017-08-01

Since the 2011 Tohoku-Oki earthquake, multi-disciplinary observational studies have promoted our understanding of both the coseismic and long-term behaviour of the Japan Trench subduction zone. We also have suggestions for mechanical properties of the fault from the experimental side. In the present study, numerical models of earthquake sequences are presented, accounting for the experimental outcomes and being consistent with observations of both long-term and coseismic fault behaviour and thermal measurements. Among the constraints, a previous study of friction experiments for samples collected in the Japan Trench Fast Drilling Project (JFAST) showed complex rate dependences: a and a-b values change with the slip rate. In order to express such complexity, we generalize a rate- and state-dependent friction law to a quadratic form in terms of the logarithmic slip rate. The constraints from experiments reduced the degrees of freedom of the model significantly, and we managed to find a plausible model by changing only a few parameters. Although potential scale effects between lab experiments and natural faults are important problems, experimental data may be useful as a guide in exploring the huge model parameter space. This article is part of the themed issue 'Faulting, friction and weakening: from slow to fast motion'.

Fracturing, fluid-rock interaction and mineralisation during the seismic cycle along the Alpine Fault

NASA Astrophysics Data System (ADS)

Williams, Jack N.; Toy, Virginia G.; Smith, Steven A. F.; Boulton, Carolyn

2017-10-01

The Alpine Fault has a <50 m wide geochemically distinct hanging-wall alteration zone. Using a combination of petrological and cathodoluminescence (CL) microscopy, Energy Dispersive Spectroscopy and X-ray diffraction, we document the habitat and mineralising phases of macro- and micro-fractures within the alteration zone using samples derived from outcrop and the Deep Fault Drilling Project. Veins predominantly contain calcite, chlorite, K-feldspar or muscovite. Gouge-filled fractures are also observed and reflect filling from mechanical wear and chlorite mineralisation. CL imaging suggests that each calcite vein was opened and sealed in one episode, possibly corresponding to a single seismic cycle. The thermal stability of mineralising phases and their mutually cross-cutting relationships indicates a cyclic history of fracture opening and mineralisation that extends throughout the seismogenic zone. Cataclasites contain intragranular veins that are hosted within quartzofeldspathic clasts, as well as veins that cross-cut clasts and the surrounding matrix. Intragranular calcite veins formed prior to or during cataclasis. Cross-cutting veins are interpreted to have formed by fracturing of relatively indurated cataclasites after near-surface slip localisation within the Alpine Fault's principal slip zone gouges (PSZs). These observations clearly demonstrate that shear strain is most localised in the shallowest part of the seismogenic zone.

Frictional properties of exhumed fault gouges in DFDP-1 cores, Alpine Fault, New Zealand

USGS Publications Warehouse

Boulton, Carolyn; Moore, Diane E.; Lockner, David A.; Toy, Virginia G.; Townend, John; Southerland, Rupert

2014-01-01

Principal slip zone gouges recovered during the Deep Fault Drilling Project (DFDP-1), Alpine Fault, New Zealand, were deformed in triaxial friction experiments at temperatures, T, of up to 350°C, effective normal stresses, σn′, of up to 156 MPa, and velocities between 0.01 and 3 µm/s. Chlorite/white mica-bearing DFDP-1A blue gouge, 90.62 m sample depth, is frictionally strong (friction coefficient, μ, 0.61–0.76) across all experimental conditions tested (T = 70–350°C, σn′ = 31.2–156 MPa); it undergoes a transition from positive to negative rate dependence as T increases past 210°C. The friction coefficient of smectite-bearing DFDP-1B brown gouge, 128.42 m sample depth, increases from 0.49 to 0.74 with increasing temperature and pressure (T = 70–210°C, σn′ = 31.2–93.6 MPa); the positive to negative rate dependence transition occurs as T increases past 140°C. These measurements indicate that, in the absence of elevated pore fluid pressures, DFDP-1 gouges are frictionally strong under conditions representative of the seismogenic crust.

Earthquake sequence simulations with measured properties for JFAST core samples.

PubMed

Noda, Hiroyuki; Sawai, Michiyo; Shibazaki, Bunichiro

2017-09-28

Since the 2011 Tohoku-Oki earthquake, multi-disciplinary observational studies have promoted our understanding of both the coseismic and long-term behaviour of the Japan Trench subduction zone. We also have suggestions for mechanical properties of the fault from the experimental side. In the present study, numerical models of earthquake sequences are presented, accounting for the experimental outcomes and being consistent with observations of both long-term and coseismic fault behaviour and thermal measurements. Among the constraints, a previous study of friction experiments for samples collected in the Japan Trench Fast Drilling Project (JFAST) showed complex rate dependences: a and a - b values change with the slip rate. In order to express such complexity, we generalize a rate- and state-dependent friction law to a quadratic form in terms of the logarithmic slip rate. The constraints from experiments reduced the degrees of freedom of the model significantly, and we managed to find a plausible model by changing only a few parameters. Although potential scale effects between lab experiments and natural faults are important problems, experimental data may be useful as a guide in exploring the huge model parameter space.This article is part of the themed issue 'Faulting, friction and weakening: from slow to fast motion'. © 2017 The Author(s).

Detachment Faulting, Serpentinization, Fluids and Life: Preliminary Results of IODP Expedition 357 (Atlantis Massif, MAR 30°N)

NASA Astrophysics Data System (ADS)

Fruh-Green, G. L.; Orcutt, B.; Green, S.; Cotterill, C.

2016-12-01

We present an overview of IODP Expedition 357, which successfully used two seabed rock drills to core 17 shallow holes at 9 sites across Atlantis Massif (Mid-Atlantic Ridge 30°N). A major goal of this expedition is to investigate serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. More than 57 m of core were recovered, with borehole penetration ranging from 1.3 to 16.4 meters below seafloor, and core recovery as high as 75% of total penetration. The cores show highly heterogeneous rock type, bulk rock chemistry and alteration that reflect multiple phases of magmatism and fluid-rock interaction within the detachment fault zone. In cores along an E-W transect of the southern wall, recovered mantle peridotites are locally intruded by gabbroic and doleritic dikes and veins. The proportion of mafic rocks are volumetrically less than the amount of mafic rocks recovered previously in the central dome at IODP Site U1309, suggesting a lower degree of melt infiltration into mantle peridotite at the ridge-transform intersection. New technologies were developed and successfully applied for the first time: (1) an in-situ sensor package and water sampling system on each seabed drill measured real-time variations in dissolved methane, oxygen, pH, oxidation reduction potential, temperature, and conductivity during drilling and took water samples after drilling; (2) a borehole plug system to seal the boreholes was successfully deployed at two sites to allow access for future sampling; and (3) delivery of chemical tracers into the drilling fluids for contamination testing. We will provide an overview of the drilling strategy and preliminary results of Expedition 357, and highlight the role of serpentinization in sustaining microbial communities in a region of active serpentinization and low temperature hydrothermal alteration.

Auto-Calibration and Fault Detection and Isolation of Skewed Redundant Accelerometers in Measurement While Drilling Systems.

PubMed

Seyed Moosavi, Seyed Mohsen; Moaveni, Bijan; Moshiri, Behzad; Arvan, Mohammad Reza

2018-02-27

The present study designed skewed redundant accelerometers for a Measurement While Drilling (MWD) tool and executed auto-calibration, fault diagnosis and isolation of accelerometers in this tool. The optimal structure includes four accelerometers was selected and designed precisely in accordance with the physical shape of the existing MWD tool. A new four-accelerometer structure was designed, implemented and installed on the current system, replacing the conventional orthogonal structure. Auto-calibration operation of skewed redundant accelerometers and all combinations of three accelerometers have been done. Consequently, biases, scale factors, and misalignment factors of accelerometers have been successfully estimated. By defecting the sensors in the new optimal skewed redundant structure, the fault was detected using the proposed FDI method and the faulty sensor was diagnosed and isolated. The results indicate that the system can continue to operate with at least three correct sensors.

Auto-Calibration and Fault Detection and Isolation of Skewed Redundant Accelerometers in Measurement While Drilling Systems

PubMed Central

Seyed Moosavi, Seyed Mohsen; Moshiri, Behzad; Arvan, Mohammad Reza

2018-01-01

The present study designed skewed redundant accelerometers for a Measurement While Drilling (MWD) tool and executed auto-calibration, fault diagnosis and isolation of accelerometers in this tool. The optimal structure includes four accelerometers was selected and designed precisely in accordance with the physical shape of the existing MWD tool. A new four-accelerometer structure was designed, implemented and installed on the current system, replacing the conventional orthogonal structure. Auto-calibration operation of skewed redundant accelerometers and all combinations of three accelerometers have been done. Consequently, biases, scale factors, and misalignment factors of accelerometers have been successfully estimated. By defecting the sensors in the new optimal skewed redundant structure, the fault was detected using the proposed FDI method and the faulty sensor was diagnosed and isolated. The results indicate that the system can continue to operate with at least three correct sensors. PMID:29495434

Evolution of petrophysical properties of across natural faults: a study on cores from the Tournemire underground research laboratory (France)

NASA Astrophysics Data System (ADS)

Bonnelye, Audrey; David, Christian; Schubnel, Alexandre; Wassermann, Jérôme; Lefèvre, Mélody; Henry, Pierre; Guglielmi, Yves; Castilla, Raymi; Dick, Pierre

2017-04-01

Faults in general, and in clay materials in particular, have complex structures that can be linked to both a polyphased tectonic history and the anisotropic nature of the material. Drilling through faults in shaly materials allows one to measure properties such as the structure, the mineralogical composition, the stress orientation or physical properties. These relations can be investigated in the laboratory in order to have a better understanding on in-situ mechanisms. In this study we used shales of Toarcian age from the Tournemire underground research laboratory (France). We decided to couple different petrophysical measurements on core samples retrieved from a borehole drilled perpendicularly to a fault plane, and the fault size is of the order of tens of meters. This 25m long borehole was sampled in order to perform several types of measurements: density, porosity, saturation directly in the field, and velocity of elastic waves and magnetic susceptibility anisotropy in the laboratory. For all these measurements, special protocols were developed in order to preserve as much as possible the saturation state of the samples. All these measurements were carried out in three zones that intersects the borehole: the intact zone , the damaged zone and the fault core zone. From our measurements, we were able to associate specific properties to each zone of the fault. We then calculated Thomsen's parameters in order to quantify the elastic anisotropy across the fault. Our results show strong variations of the elastic anisotropy with the distance to the fault core as well as the occurrence of anisotropy reversal.

Recent scientific and operational achievements of D/V Chikyu

NASA Astrophysics Data System (ADS)

Taira, Asahiko; Toczko, Sean; Eguchi, Nobu; Kuramoto, Shin'ichi; Kubo, Yusuke; Azuma, Wataru

2014-12-01

The D/V Chikyu, a scientific drilling vessel, is equipped with industry-standard riser capabilities. Riser drilling technology enables remarkable drilling and downhole logging capabilities and provides unprecedented hole-stability, enabling the shipboard team to retrieve high-quality wire-line logging data as well as well-preserved core samples. The 11 March 2011 Tohoku Oki mega-earthquake and tsunami cost over 18,000 casualties in NE Japan. Chikyu, docked in the Port of Hachinohe, was damaged by the tsunami. By April 2012, the ship was back in operation; drilling the toe of the Japan Trench fault zone where topographic surveys suggested there was up to 50 m eastward motion, the largest earthquake rupture ever recorded. During Integrated Ocean Drilling Program (IODP) Expeditions 343 and 343 T, Chikyu drilled 850 m below sea floor (mbsf) in 6,900+ m water depth and recovered core samples of a highly brecciated shear zone composed of pelagic claystone. A subseafloor observatory looking for temperature signatures caused by the fault friction during the earthquake, was installed and later successfully recovered. The recovered temperature loggers recorded data from which the level of friction during the mega-earthquake slip could be determined. Following Exp. 343, Chikyu began IODP Exp. 337, a riser drilling expedition into the Shimokita coal beds off Hachinohe, to study the deep subsurface biosphere in sedimentary units including Paleogene-Neogene coal beds. New records in scientific ocean drilling were achieved in deepest penetration (drilling reached 2,466 mbsf) and sample recovery. Currently Chikyu is conducting deep riser drilling at the Nankai Trough in the final stage of the NanTroSEIZE campaign. During the years 2011 to 2013, including drilling in the Okinawa Hydrothermal System, Chikyu's operational and scientific achievements have demonstrated that the ship's capabilities are vital for opening new frontiers in earth and biological sciences.

The postglacial Stuoragurra Fault, North Norway - A textural and mineralogical study.

NASA Astrophysics Data System (ADS)

Roaldset, E.

2012-04-01

The postglacial Stuoragurra Fault, North Norway - A textural and mineralogical study Elen Roaldset(1), Mari Åm (2), and Oddleiv Olesen(3) 1) Natural History Museum, University of Oslo, P.O.Box 1172 Blindern, 0318 Oslo, Norway 2) Statoil R &D, P. O. Box 2470, 7005 Trondheim, Norway 3) Norwegian Geological Survey, P.O.Box 6315 Sluppen, 7491 Trondheim, Norway The Stuoragurra Fault is part of the Lapland province of postglacial faults and was identified in 1983 during a colloborative project between the Geological Surveys of Finland Norway and Sweden. The Stuoragurra Fault is an 80 km long fault zone which contains three main segments of eastward dipping faults (30-55 deg.) with up to 10 m of reverse displacement and a 7 m high escarpment. It cross-cuts glaciofluvial deposits and consequently being younger than 10.000 years. The postglacial fault segments follow to a large extent older fault zones represented by lithified breccias and diabases of Proterozoic age. In this paper we will present textural and mineralogical study of a 135 m continous core drilled across the fault zone. The investigation methods include quality assessments by rock quality designation methods (RQD and Q- methods), textural and petrological descriptions visually and by thin section microscopy, and mineralogical analysis by X-ray diffraction. Special attention is drawn to neoformed and/or degraded minerals like clay minerals and iron oxides/hydroxides. The quality assessments of the cored material reflect the degree of rock deformation and fragmentation and show the quality of the bedrock generally to be of very poor (about 60%) to poor quality" (25%) The main minerals in the fresh rock are quarts, feldspar, mica and iron oxides (magnetite and ilmenite). Throughout the cored borehole products of weathering have formed on fissures, fractures and in strongly deformed, gravelly, zones. The neoformed minerals include kaolinite, smectite, and vermiculite, as well as goethite. The mineralogical transformations will be discussed in relation to the rock texture,petrophysical properties and fault characteristics.

Fault detection and diagnosis for gas turbines based on a kernelized information entropy model.

PubMed

Wang, Weiying; Xu, Zhiqiang; Tang, Rui; Li, Shuying; Wu, Wei

2014-01-01

Gas turbines are considered as one kind of the most important devices in power engineering and have been widely used in power generation, airplanes, and naval ships and also in oil drilling platforms. However, they are monitored without man on duty in the most cases. It is highly desirable to develop techniques and systems to remotely monitor their conditions and analyze their faults. In this work, we introduce a remote system for online condition monitoring and fault diagnosis of gas turbine on offshore oil well drilling platforms based on a kernelized information entropy model. Shannon information entropy is generalized for measuring the uniformity of exhaust temperatures, which reflect the overall states of the gas paths of gas turbine. In addition, we also extend the entropy to compute the information quantity of features in kernel spaces, which help to select the informative features for a certain recognition task. Finally, we introduce the information entropy based decision tree algorithm to extract rules from fault samples. The experiments on some real-world data show the effectiveness of the proposed algorithms.

High sedimentation rates and thrust fault modulation: Insights from ocean drilling offshore the St. Elias Mountains, southern Alaska

NASA Astrophysics Data System (ADS)

Worthington, Lindsay L.; Daigle, Hugh; Clary, Wesley A.; Gulick, Sean P. S.; Montelli, Aleksandr

2018-02-01

The southern Alaskan margin offshore the St. Elias Mountains has experienced the highest recorded offshore sediment accumulation rates globally. Combined with high uplift rates, active convergence and extensive temperate glaciation, the margin provides a superb setting for evaluating competing influences of tectonic and surface processes on orogen development. We correlate results from Integrated Ocean Drilling Program (IODP) Expedition 341 Sites U1420 and U1421 with regional seismic data to determine the spatial and temporal evolution of the Pamplona Zone fold-thrust belt that forms the offshore St. Elias deformation front on the continental shelf. Our mapping shows that the pattern of active faulting changed from distributed across the shelf to localized away from the primary glacial depocenter over ∼300-780 kyrs, following an order-of-magnitude increase in sediment accumulation rates. Simple Coulomb stress calculations show that the suppression of faulting is partially controlled by the change in sediment accumulation rates which created a differential pore pressure regime between the underlying, faulted strata and the overlying, undeformed sediments.

Fault Detection and Diagnosis for Gas Turbines Based on a Kernelized Information Entropy Model

PubMed Central

Wang, Weiying; Xu, Zhiqiang; Tang, Rui; Li, Shuying; Wu, Wei

2014-01-01

Gas turbines are considered as one kind of the most important devices in power engineering and have been widely used in power generation, airplanes, and naval ships and also in oil drilling platforms. However, they are monitored without man on duty in the most cases. It is highly desirable to develop techniques and systems to remotely monitor their conditions and analyze their faults. In this work, we introduce a remote system for online condition monitoring and fault diagnosis of gas turbine on offshore oil well drilling platforms based on a kernelized information entropy model. Shannon information entropy is generalized for measuring the uniformity of exhaust temperatures, which reflect the overall states of the gas paths of gas turbine. In addition, we also extend the entropy to compute the information quantity of features in kernel spaces, which help to select the informative features for a certain recognition task. Finally, we introduce the information entropy based decision tree algorithm to extract rules from fault samples. The experiments on some real-world data show the effectiveness of the proposed algorithms. PMID:25258726

Paleomagnetism of the Oman Ophiolite: New Results from Oman Drilling Project Cores

NASA Astrophysics Data System (ADS)

Horst, A. J.; Till, J. L.; Koornneef, L.; Usui, Y.; Kim, H.; Morris, A.

2017-12-01

The Oman Drilling Project drilled holes at four sites in a transect through the southern massifs of the Samail ophiolite, and recovered 1500 m of igneous and metamorphic rocks. We focus on three sites from the oceanic crustal section including lower layered gabbros (GT1A), the mid-crustal layered to foliated gabbro transition (GT2A), and the shallower transition from sheeted dikes to varitextured gabbros (GT3A). Detailed core descriptions, analyses, and paleomagnetic measurements, were made on D/V Chikyu from July to September 2017 to utilize the core laboratory facilities similar to IODP expeditions. Shipboard measurements included anisotropy of magnetic susceptibility (AMS) and alternating field and thermal demagnetization of 597 discrete samples. Sample demagnetization behavior is varied from each of the cores, with some revealing multiple components of magnetization, and others yielding nearly univectorial data. The interpretation of results from the lower crustal cores is complicated by the pervasive presence of secondary magnetite. In almost all samples, a stable component was resolved (interpreted as a characteristic remanent magnetization) after removal of a lower-coercivity or lower unblocking-temperature component. The inclinations of the stable components in the core reference frame are very consistent in Hole GT1A. However, a transition from negative to positive inclinations in GT2A suggests some structural complexity, possibly as a result of intense late faulting activity. Both abrupt and gradual transitions between multiple zones of negative and positive inclinations occur in Hole GT3A. Interpretation and direct comparison of remanence between drill sites is difficult as recovered core pieces currently remain azimuthally unoriented, and GT2A was drilled at a plunge of 60°, whereas GT1A and GT3A were both drilled vertically. Work is ongoing to use borehole imagery to reorient the core pieces and paleomagnetic data into a geographic in situ reference frame. We will present an overview of preliminary AMS and remanence data that will be used in the future to 1) document deformational histories, 2) characterize magmatic flow directions at different structural levels, and 3) identify the magnetic mineralogy of remanence carriers throughout the oceanic crustal section.

Technical know-how relevant to planning of borehole investigation for fault characterization

NASA Astrophysics Data System (ADS)

Mizuno, T.; Takeuchi, R.; Tsuruta, T.; Matsuoka, T.; Kunimaru, T.; Saegusa, H.

2011-12-01

As part of the national R&D program for geological disposal of high-level radioactive waste (HLW), the broad scientific study of the deep geological environment, JAEA has established the Mizunami Underground Research Laboratory (MIU) in Central Japan as a generic underground research laboratory (URL) facility. The MIU Project focuses on the crystalline rocks. In the case of fractured rock, a fault is one of the major discontinuity structures which control the groundwater flow conditions. It is important to estimate geological, hydrogeological, hydrochemical and rock mechanical characteristics of faults, and then to evaluate its role in the engineering design of repository and the assessment of long-term safety of HLW disposal. Therefore, investigations for fault characterization have been performed to estimate its characteristics and to evaluate existing conceptual and/or numerical models of the geological environment in the MIU project. Investigations related to faults have been conducted based on the conventional concept that a fault consists of a "fault core (FC)" characterized by distribution of the faulted rocks and a "fractured zone (FZ)" along FC. With the progress of investigations, furthermore, it is clear that there is also a case in which an "altered zone (AZ)" characterized by alteration of host rocks to clay minerals can be developed around the FC. Intensity of alteration in AZ generally decreases with distance from the FC, and AZ transits to FZ. Therefore, the investigation program focusing on properties of AZ is required for revising the existing conceptual and/or numerical models of geological environment. In this study, procedures for planning of fault characterizations have been summarized based on the technical know-how learnt through the MIU Project for the development of Knowledge Management System performed by JAEA under a contract with the Ministry of Economy, Trade and Industry as part of its R&D supporting program for developing geological disposal technology in 2010. Taking into account the experience from the fault characterization in the MIU Project, an optimization procedure for investigation program is summarized as follows; 1) Definition of investigation aim, 2) Confirmation of current understanding of the geological environment, 3) Specification and prioritization of the data to be obtained 4) Selection of the methodology for obtaining the data, 5) Specification of sequence of the investigations, and 6) Establishment of drilling and casing program including optional cases and taking into account potential problems. Several geological conceptual models with uncertainty of geological structures were illustrated to define the investigation aim and to confirm the current uncertainties. These models were also available to establish optional cases by predicting the type and location of potential problems. The procedures and case study related to establishment of the investigation program are summarized in this study and can be available for site characterization works conducted by the implementing body (NUMO) in future candidate areas.

IODP drilling in the South China Sea in 2017 will address the mechanism of continental breakup

NASA Astrophysics Data System (ADS)

Sun, Z.; Larsen, H. C.; Lin, J.; Pang, X.; McIntosh, K. D.; Stock, J. M.; Jian, Z.; Wang, P.; Li, C.

2016-12-01

Geophysical exploration and scientific drilling along the North Atlantic rifted continental margins suggested that passive continental margins can be classified into two end members: magma-rich and magma-poor. Bearing seaward-dipping reflector sequences (SDRS) and highly mafic underplated high velocity lower crust (HVLC), the magma-rich margin is thought to be related to large igneous provinces (LIP) or mantle plume activity. Magma-poor margins have been drilled offshore Iberia and Newfoundland, where brittle faults cut through the whole crust and reach the upper mantle. Following seawater infiltration, the mantle was serpentinized and exhumed in the continent-ocean transition zone (COT). Later geophysical exploration and modeling suggested that in magma-poor margins lithosphere may break up in different styles, including uniform breakup, lower crust exhumation, or upper mantle exhumed at the COT, etc. The northern continental margin of the South China Sea (SCS) between longitude 114.5º and 116.5º hosts features that might be similar to both of the two end-members defined in the North Atlantic. Wide-angle seismic studies suggest that below the inner margin, crustal underplating of high velocity material is present, while syn-rift as well as post-rift intrusive features are visible and have in places been verified by industry drilling. However, the profound volcanism and associated SDRS formation are entirely lacking, and thus classification as a volcanic rifted margin can be ruled out. Instead, the COT exhibits a profound thinning of the continental crust towards the ocean crust of the SCS, showing some similarity to the Iberia type margin. The crustal thinning is caused by low-angle faults that have stretched the upper continental crust. There are indications of lower crustal flow toward the SCS. Alternatively, these extensional faults may have reached the lithospheric mantle and generated serpentinized material in a similar fashion as seen off Iberia. It will require deep drilling and sampling of characteristic basement units within the COT to distinguish. Four months of drilling by IODP to address this question is scheduled for February to June in 2017. The IODP drilling has the potential to support a third breakup mechanism theorized by modelling in addition to the two types drilled.

Development of a Methodology for Hydrogeological Characterization of Faults: Progress of the Project in Berkeley, California

NASA Astrophysics Data System (ADS)

Goto, J.; Moriya, T.; Yoshimura, K.; Tsuchi, H.; Karasaki, K.; Onishi, T.; Ueta, K.; Tanaka, S.; Kiho, K.

2010-12-01

The Nuclear Waste Management Organization of Japan (NUMO), in collaboration with Lawrence Berkeley National Laboratory (LBNL), has carried out a project to develop an efficient and practical methodology to characterize hydrologic property of faults since 2007, exclusively for the early stage of siting a deep underground repository. A preliminary flowchart of the characterization program and a classification scheme of fault hydrology based on the geological feature have been proposed. These have been tested through the field characterization program on the Wildcat Fault in Berkeley, California. The Wildcat Fault is a relatively large non-active strike-slip fault which is believed to be a subsidiary of the active Hayward Fault. Our classification scheme assumes the contrasting hydrologic features between the linear northern part and the split/spread southern part of the Wildcat Fault. The field characterization program to date has been concentrated in and around the LBNL site on the southern part of the fault. Several lines of electrical and reflection seismic surveys, and subsequent trench investigations, have revealed the approximate distribution and near-surface features of the Wildcat Fault (see also Onishi, et al. and Ueta, et al.). Three 150m deep boreholes, WF-1 to WF-3, have been drilled on a line normal to the trace of the fault in the LBNL site. Two vertical holes were placed to characterize the undisturbed Miocene sedimentary formations at the eastern and western sides of the fault (WF-1 and WF-2 respectively). WF-2 on the western side intersected the rock formation, which was expected only in WF-1, and several of various intensities. Therefore, WF-3, originally planned as inclined to penetrate the fault, was replaced by the vertical hole further to the west. It again encountered unexpected rocks and faults. Preliminary results of in-situ hydraulic tests suggested that the transmissivity of WF-1 is ten to one hundred times higher than WF-2. The monitoring of hydraulic pressure displayed different head distribution patterns between WF-1 and WF-2 (see also Karasaki, et al.). Based on these results, three hypotheses on the distribution of the Wildcat Fault were proposed: (a) a vertical fault in between WF-1 and WF-2, (b) a more gently dipping fault intersected in WF-2 and WF-3, and (c) a wide zone of faults extending between WF-1 and WF-3. At present, WF-4, an inclined hole to penetrate the possible (eastern?) master fault, is ongoing to test these hypotheses. After the WF-4 investigation, hydrologic and geochemical analyses and modeling of the southern part of the fault will be carried out. A simpler field characterization program will also be carried out in the northern part of the fault. Finally, all the results will be synthesized to improve the comprehensive methodology.

Paleomagnetic Reorientation of Structural Elements in Drill Cores: an example from Tolhuaca Geothermal Field

NASA Astrophysics Data System (ADS)

Perez-Flores, P.; Veloso, E. E.; Cembrano, J. M.; Sánchez, P.; Iriarte, S.; Lohmar, S.

2013-12-01

Reorientation of mesoscopic faults, veins and fractures recovered from drilling is critical to construct reliable structural models that can account for their architecture and deformation regime. However, oriented cores are expensive and time consuming to drill. Some techniques achieve reorientation by introducing tools into the borehole. Problems arise when boreholes are unstable or collapse. One alternative technique allowing reorientation is to obtain reliable paleomagnetic vectors to reorient each core piece after drilling. Here, we present stable and reliable remnant magnetic vectors calculated from the Tol-1 core to analyze the geometry of the fracture network and its relationship to regional tectonic. Tol-1 core is a vertical, 1073 m deep geothermal well, drilled at the Tolhuaca Geothermal Field in the Southern Volcanic Zone of the Andes by MRP Geothermal Chile Ltda (formerly GGE Chile SpA) in 2009. The core consists of basaltic/andesitic volcanic rocks with subordinate pyroclastic/volcaniclastic units, with probable Pleistocene age. Fault planes with slickenlines and mineral fiber kinematic indicators are common in the upper 700 m of the core. Calcite, quartz and calcite-quartz veins are recognized along of entire core, whereas epidote-quartz and calcite-epidote veins occur in the last 350 m, minor chlorite, anhydrite and clay-minerals are present. Orientations of structural features in the core were measured with a goniometer using the core's axis and a false north for each piece; hence, orientation data has a false strike but a real dip. To achieve total reorientation of the pieces, we collected 200 standard-size paleomagnetic specimens, ensuring that at least four of them were recovered from continuous pieces. Thermal (up to 700°C) and alternating field demagnetization (up to 90mT on steps of 2mT) methods were used to isolate a stable remnant magnetization (RM) vector, and each technique yielded similar results. RM vectors were recovered between 0 to 25mT, and between 0 to 625°C. The declination of RM vectors was used to bring pieces to a common anchor orientation calculated through the Geocentric Axial Dipole Model (GAD). The paleomagnetic technique proved to be reliable to reorient the Tol-1 core. Structural analyses along the core show N50-60E-striking preferential vein orientation. In addition, N40-50E- and N60-70W-striking preferential fault orientations were identified. Kinematic analysis of fault-slip data shows a N60E-striking bulk fault plane solution with normal strain regime. The veins and faults orientation show strain axes compatible with published regional stress field (σmax N238E).

3-Dimensional Geologic Modeling Applied to the Structural Characterization of Geothermal Systems: Astor Pass, Nevada, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siler, Drew L; Faulds, James E; Mayhew, Brett

2013-04-16

Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to broad-scale geothermal circulation is crucial to both the mitigation of the costs of geothermal exploration (especially drilling) and to the identification of geothermal systems that have no surface expression (blind systems). 3-dimensional geologic modeling is a tool that can elucidate the specific stratigraphic intervals and structural geometries that host geothermal reservoirs. Astor Pass, NV USA lies just beyond the northern extent of the dextral Pyramid Lake fault zone near the boundarymore » between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present. Previous studies at Astor Pass identified a blind geothermal system controlled by the intersection of west-northwest and north-northwest striking dextral-normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94°C fluids, with geothermometers suggesting a maximum reservoir temperature of 130°C. A 3-dimensional model was constructed based on detailed geologic maps and cross-sections, 2-dimensional seismic data, and petrologic analysis of the cuttings from three wells in order to further constrain the structural setting. The model reveals the specific geometry of the fault interaction area at a level of detail beyond what geologic maps and cross-sections can provide.« less

Borehole Breakout Derived Constraints on Stress Regimes in the Santa Barbara Channel, Offshore Southern California

NASA Astrophysics Data System (ADS)

Pritchard, E. H.; Persaud, P.; Stock, J. M.

2017-12-01

The Santa Barbara Channel is an E-W trending marine basin that serves as the southern extension of the Western Transverse Ranges block. Several active, E-W trending en echelon fault systems exist beneath the Channel with both N and S dips. These control a series of tight, asymmetric anticlinal folds along the North Channel and Mid-Channel regions. Although controversial, recent models have suggested that these systems are capable of producing large magnitude, tsunamigenic earthquakes. Not controversial, however, is the fact that further knowledge of the stress regime related to these systems would greatly contribute to our understanding of a potential rupture along them. In this study, oriented 4-arm caliper well log data obtained from industry are used to determine the orientations of stress induced shear failures along well bore walls, called borehole breakouts, beneath two offshore drill platforms in the Santa Barbara Channel. Analysis of breakout orientations along 18 differently oriented, highly deviated wells allows for constraint of the current in situ stress regime beneath each of the platforms. The best-fit stress regime can then be used to inform the nature of slip along nearby faults, many of which are blind and display no surface indications of slip. At the Holly platform, located roughly 19 km west of Santa Barbara, and proximate to the Pitas Point, North Channel, and Red Mountain fault systems, lower hemisphere polar projections of breakout orientations in deviated well sections indicate a mainly thrust faulting stress regime, although a strike-slip component is not currently excluded. At the Gail platform, located midway between Ventura and Santa Cruz Island, and proximate to the Western Deep Fault, polar projections of breakouts indicate that a predominantly thrust faulting stress regime also exists beneath this platform. However, a few inconsistencies in the breakout orientations at each platform suggest variability in the stress regime, leading to the hypothesis that the stress field beneath these regions may change with depth, from a shallow degenerate-like thrust faulting stress state, with the horizontal principal stresses roughly equal in magnitude yet greater than the vertical principal stress (SH = Sh > Sv), to a deeper, less degenerate regime.

Hydraulic Fracture Induced Seismicity During A Multi-Stage Pad Completion in Western Canada: Evidence of Activation of Multiple, Parallel Faults

NASA Astrophysics Data System (ADS)

Maxwell, S.; Garrett, D.; Huang, J.; Usher, P.; Mamer, P.

2017-12-01

Following reports of injection induced seismicity in the Western Canadian Sedimentary Basin, regulators have imposed seismic monitoring and traffic light protocols for fracturing operations in specific areas. Here we describe a case study in one of these reservoirs, the Montney Shale in NE British Columbia, where induced seismicity was monitored with a local array during multi-stage hydraulic fracture stimulations on several wells from a single drilling pad. Seismicity primarily occurred during the injection time periods, and correlated with periods of high injection rates and wellhead pressures above fracturing pressures. Sequential hydraulic fracture stages were found to progressively activate several parallel, critically-stressed faults, as illuminated by multiple linear hypocenter patterns in the range between Mw 1 and 3. Moment tensor inversion of larger events indicated a double-couple mechanism consistent with the regional strike-slip stress state and the hypocenter lineations. The critically-stressed faults obliquely cross the well paths which were purposely drilled parallel to the minimum principal stress direction. Seismicity on specific faults started and stopped when fracture initiation points of individual injection stages were proximal to the intersection of the fault and well. The distance ranges when the seismicity occurs is consistent with expected hydraulic fracture dimensions, suggesting that the induced fault slip only occurs when a hydraulic fracture grows directly into the fault and the faults are temporarily exposed to significantly elevated fracture pressures during the injection. Some faults crossed multiple wells and the seismicity was found to restart during injection of proximal stages on adjacent wells, progressively expanding the seismogenic zone of the fault. Progressive fault slip is therefore inferred from the seismicity migrating further along the faults during successive injection stages. An accelerometer was also deployed close to the pad operations providing information about the local ground motion at near offsets, although no ground motion was recorded that exceeds the minimum levels requiring mandatory reporting to the regulator.

Refined images of the crust around the SAFOD drill site derived from combined active and passive seismic experiment data

NASA Astrophysics Data System (ADS)

Roecker, S.; Thurber, C.; Shuler, A.; Liu, Y.; Zhang, H.; Powell, L.

2005-12-01

Five years of effort collecting and analyzing earthquake and explosion data in the vicinity of the SAFOD drill site culminated in the determination of the final trajectory for summer 2005's Phase 2 drilling. The trajectory was defined to optimize the chance of reaching one of two adjacent M2 "target earthquake" fault patches, whose centroids are separated horizontally by about 50 meters, with one or more satellite coreholes planned for Phase 3 drilling in summer 2007. Some of the most critical data for the final targeting were explosion data recorded on a Paulsson Geophysical Services, Inc., 80-element 3-component borehole string and earthquake data recorded on a pair of 3-component Duke University geophones in the SAFOD borehole. We are now utilizing the full 5-year dataset to refine our knowledge of three-dimensional (3D) crustal structure, wave propagation characteristics, and earthquake locations around SAFOD. These efforts are proceeding in parallel in several directions. Improved picks from a careful reanalysis of shear waves observed on the PASO array will be used in deriving an improved tomographic 3D wavespeed model. We are using finite-difference waveform modeling to investigate waveform complexity for earthquakes in and near the target region, including fault-zone head waves and strong secondary S-wave arrivals. A variety of waveform imaging methods are being applied to image fine-scale 3D structure and subsurface scatterers, including fault zones. In the process, we aim to integrate geophysical logging and geologic observations with our models to try to associate the target region earthquake activity, which is occurring on two fault strands about 280 meters apart, with shear zones encountered in the SAFOD Phase-2 borehole. These observations will be agumented and the target earthquake locations further refined over the next 2 years through downhole and surface recording of natural earthquakes and surface shots conducted at PASO station locations.

Groundwater Exploration for Rural Communities in Ghana, West Africa

NASA Astrophysics Data System (ADS)

McKay, W. A.

2001-05-01

Exploration for potable water in developing countries continues to be a major activity, as there are more than one billion people without access to safe drinking water. Exploration for groundwater becomes more critical in regions where groundwater movement and occurrence is controlled by secondary features such as fractures and faults. Drilling success rates in such geological settings are generally very low, but can be improved by integrating geological, hydrogeological, aerial photo interpretation with land-based geophysical technology in the selection of drilling sites. To help alleviate water supply problems in West Africa, the Conrad N. Hilton Foundation and other donors, since 1990, have funded the World Vision Ghana Rural Water Project (GRWP) to drill wells for potable water supplies in the Greater Afram Plains (GAP) of Ghana. During the first two years of the program, drilling success rates using traditional methods ranged from 35 to 80 percent, depending on the area. The average drilling success rate for the program was approximately 50 percent. In an effort to increase the efficiency of drilling operations, the Desert Research Institute evaluated and developed techniques for application to well-siting strategies in the GAP area of Ghana. A critical project element was developing technical capabilities of in-country staff to independently implement the new strategies. Simple cost-benefit relationships were then used to evaluate the economic advantages of developing water resources using advanced siting methods. The application of advanced methods in the GAP area reveal an increase of 10 to 15 percent in the success rate over traditional methods. Aerial photography has been found to be the most useful of the imagery products covering the GAP area. An effective approach to geophysical exploration for groundwater has been the combined use of EM and resistivity methods. Economic analyses showed that the use of advanced methods is cost-effective when success rates with traditional methods are less than 70 to 90 percent. Finally, with the focus of GRWP activities shifting to Ghana's northern regions, new challenges in drilling success rates are being encountered. In certain districts, success rates as low as 35 percent are observed, raising questions about the efficacy of existing well-siting strategies in the current physical setting, and the validity of traditional cost-benefit analyses for assessing the economic aspects of water exploration in drought-stricken areas.

Evolution of the continental margin of southern Spain and the Alboran Sea

USGS Publications Warehouse

Dillon, William P.; Robb, James M.; Greene, H. Gary; Lucena, Juan Carlos

1980-01-01

Seismic reflection profiles and magnetic intensity measurements were collected across the southern continental margin of Spain and the Alboran basin between Spain and Africa. Correlation of the distinct seismic stratigraphy observed in the profiles to stratigraphic information obtained from cores at Deep Sea Drilling Project site 121 allows effective dating of tectonic events. The Alboran Sea basin occupies a zone of motion between the African and Iberian lithospheric plates that probably began to form by extension in late Miocene time (Tortonian). At the end of Miocene time (end of Messinian) profiles show that an angular unconformity was cut, and then the strata were block faulted before subsequent deposition. The erosion of the unconformity probably resulted from lowering of Mediterranean sea level by evaporation when the previous channel between the Mediterranean and Atlantic was closed. Continued extension probably caused the block faulting and, eventually the opening of the present channel to the Atlantic through the Strait of Gibraltar and the reflooding of the Mediterranean. Minor tectonic movements at the end of Calabrian time (early Pleistocene) apparently resulted in minor faulting, extensive transgression in southeastern Spain, and major changes in the sedimentary environment of the Alboran basin. Active faulting observed at five locations on seismic profiles seems to form a NNE zone of transcurrent movement across the Alboran Sea. This inferred fault trend is coincident with some bathymetric, magnetic and seismicity trends and colinear with active faults that have been mapped on-shore in Morocco and Spain. The faults were probably caused by stresses related to plate movements, and their direction was modified by inherited fractures in the lithosphere that floors the Alboran Sea.

Combined Application of Shallow Seismic Reflection and High-resolution Refraction Exploration Approach to Active Fault Survey, Central Orogenic Belt, China

NASA Astrophysics Data System (ADS)

Lin, S.; Luo, D.; Yanlin, F.; Li, Y.

2016-12-01

Shallow Seismic Reflection (SSR) is a major geophysical exploration method with its exploration depth range, high-resolution in urban active fault exploration. In this paper, we carried out (SSR) and High-resolution refraction (HRR) test in the Liangyun Basin to explore a buried fault. We used NZ distributed 64 channel seismic instrument, 60HZ high sensitivity detector, Geode multi-channel portable acquisition system and hammer source. We selected single side hammer hit multiple overlay, 48 channels received and 12 times of coverage. As there are some coincidence measuring lines of SSR and HRR, we chose multi chase and encounter observation system. Based on the satellite positioning, we arranged 11 survey lines in our study area with total length for 8132 meters. GEOGIGA seismic reflection data processing software was used to deal with the SSR data. After repeated tests from the aspects of single shot record compilation, interference wave pressing, static correction, velocity parameter extraction, dynamic correction, eventually got the shallow seismic reflection profile images. Meanwhile, we used Canadian technology company good refraction and tomographic imaging software to deal with HRR seismic data, which is based on nonlinear first arrival wave travel time tomography. Combined with drilling geological profiles, we explained 11 measured seismic profiles. Results show 18 obvious fault feature breakpoints, including 4 normal faults of south-west, 7 reverse faults of south-west, one normal fault of north-east and 6 reverse faults of north-east. Breakpoints buried depth is 15-18 meters, and the inferred fault distance is 3-12 meters. Comprehensive analysis shows that the fault property is reverse fault with northeast incline section, and fewer branch normal faults presenting southwest incline section. Since good corresponding relationship between the seismic interpretation results, drilling data and SEM results on the property, occurrence, broken length of the fault, we considered the Liangyun fault to be an active fault which has strong activity during the Neogene Pliocene and early Pleistocene, Middle Pleistocene period. The combined application of SSR and HRR can provide more parameters to explain the seismic results, and improve the accuracy of the interpretation.

Seismic Prediction While Drilling (SPWD): Seismic exploration ahead of the drill bit using phased array sources

NASA Astrophysics Data System (ADS)

Jaksch, Katrin; Giese, Rüdiger; Kopf, Matthias

2010-05-01

In the case of drilling for deep reservoirs previous exploration is indispensable. In recent years the focus shifted more on geological structures like small layers or hydrothermal fault systems. Beside 2D- or 3D-seismics from the surface and seismic measurements like Vertical Seismic Profile (VSP) or Seismic While Drilling (SWD) within a borehole these methods cannot always resolute this structures. The resolution is worsen the deeper and smaller the sought-after structures are. So, potential horizons like small layers in oil exploration or fault zones usable for geothermal energy production could be failed or not identified while drilling. The application of a device to explore the geology with a high resolution ahead of the drill bit in direction of drilling would be of high importance. Such a device would allow adjusting the drilling path according to the real geology and would minimize the risk of discovery and hence the costs for drilling. Within the project SPWD a device for seismic exploration ahead of the drill bit will be developed. This device should allow the seismic exploration to predict areas about 50 to 100 meters ahead of the drill bit with a resolution of one meter. At the GFZ a first prototype consisting of different units for seismic sources, receivers and data loggers has been designed and manufactured. As seismic sources four standard magnetostrictive actuators and as receivers four 3-component-geophones are used. Every unit, actuator or geophone, can be rotated in steps of 15° around the longitudinal axis of the prototype to test different measurement configurations. The SPWD prototype emits signal frequencies of about 500 up to 5000 Hz which are significant higher than in VSP and SWD. An increased radiation of seismic wave energy in the direction of the borehole axis allows the view in areas to be drilled. Therefore, every actuator must be controlled independently of each other regarding to amplitude and phase of the source signal to maximize the energy of the seismic source in order to reach a sufficient exploration range. The next step for focusing is to use the method of phased array. Dependent of the seismic wave velocities of the surrounding rock, the distance of the actuators to each other and the used frequencies the signal phases for each actuator can be determined. Since one year several measurements with the prototype have been realized under defined conditions at a test site in a mine. The test site consists of a rock block surrounded from three galleries with a dimension of about 100 by 200 meters. For testing the prototype two horizontal boreholes were drilled. They are directed to one of the gallery to get a strong reflector. The quality of the data of the borehole seismics in amplitude and frequency spectra show overall a good signal-to-noise ratio and correlate strongly with the fracture density along the borehole and are associated with a lower signal-to-noise ratio. Additionally, the geophones of the prototype show reflections from ahead and rearward in the seismic data. In particular, the reflections from the gallery ahead are used for the calibration of focusing. The direct seismic wave field indicates distinct compression and shear waves. The analysis of several seismic measurements with a focus on the direct seismic waves shows that the phased array technology explicit can influence the directional characteristics of the radiated seimic waves. The amplitudes of the seismic waves can be enhanced up to three times more in the desired direction and simultaneously be attenuated in the reverse direction. A major step for the directional investigation in boreholes has accomplished. But the focusing of the seismic waves has to be improved to maximize the energy in the desired direction in more measurements by calibrating the initiating seismic signals of the sources. A next step this year is the development of a wireline prototype for application in vertical boreholes with depths not more than 2000 meters are planned. The prototype must be modified and adapted to the conditions in deep boreholes with respect to pressure and temperature. This project is funded by the German Federal Environment Ministry.

Frictional and hydrologic behavior of the San Andreas Fault: Insights from laboratory experiments on SAFOD cuttings and core

NASA Astrophysics Data System (ADS)

Carpenter, B. M.; Marone, C.; Saffer, D. M.

2010-12-01

The debate concerning the apparent low strength of tectonic faults, including the San Andreas Fault (SAF), continues to focus on: 1) low intrinsic friction resulting from mineralogy and/or fabric, and 2) decreased effective normal stress due to elevated pore pressure. Here we inform this debate with laboratory measurements of the frictional behavior and permeability of cuttings and core returned from the SAF at a vertical depth of 2.7 km. We conducted experiments on cuttings and core recovered during SAFOD Phase III drilling. All samples in this study are adjacent to and within the active fault zone penetrated at 10814.5 ft (3296m) measured depth in the SAFOD borehole. We sheared gouge samples composed of drilling cuttings in a double-direct shear configuration subject to true-triaxial loading under constant effective normal stress, confining pressure, and pore pressure. Intact wafers of material were sheared in a single-direct shear configuration under similar conditions of effective stress, confining pressure, and pore pressure. We also report on permeability measurements on intact wafers of wall rock and fault gouge prior to shearing. Initial results from experiments on cuttings show: 1) a weak fault (µ=~0.21) compared to the surrounding wall rock (µ=~0.35), 2) velocity strengthening behavior, (a-b > 0), consistent with aseismic slip, and 3) near zero healing rates in material from the active fault. XRD analysis on cuttings indicates the main mineralogical difference between fault rock and wall rock, is the presence of significant amounts of smectite within the fault rock. Taken together, the measured frictional behavior and clay mineral content suggest that the clay composition exhibits a basic control on fault behavior. Our results document the first direct evidence of weak material from an active fault at seismogenic depths. In addition, our results could explain why the SAF in central California fails aseismically and hosts only small earthquakes.

Site selection for DOE/JIP gas hydrate drilling in the northern Gulf of Mexico

USGS Publications Warehouse

Hutchinson, Deborah; Shelander, Dianna; Dai, J.; McConnell, D.; Shedd, William; Frye, Matthew; Ruppel, Carolyn D.; Boswell, R.; Jones, Emrys; Collett, Timothy S.; Rose, Kelly K.; Dugan, Brandon; Wood, Warren T.

2008-01-01

n the late spring of 2008, the Chevron-led Gulf of Mexico Gas Hydrate Joint Industry Project (JIP) expects to conduct an exploratory drilling and logging campaign to better understand gas hydrate-bearing sands in the deepwater Gulf of Mexico. The JIP Site Selection team selected three areas to test alternative geological models and geophysical interpretations supporting the existence of potential high gas hydrate saturations in reservoir-quality sands. The three sites are near existing drill holes which provide geological and geophysical constraints in Alaminos Canyon (AC) lease block 818, Green Canyon (GC) 955, and Walker Ridge (WR) 313. At the AC818 site, gas hydrate is interpreted to occur within the Oligocene Frio volcaniclastic sand at the crest of a fold that is shallow enough to be in the hydrate stability zone. Drilling at GC955 will sample a faulted, buried Pleistocene channel-levee system in an area characterized by seafloor fluid expulsion features, structural closure associated with uplifted salt, and abundant seismic evidence for upward migration of fluids and gas into the sand-rich parts of the sedimentary section. Drilling at WR313 targets ponded sheet sands and associated channel/levee deposits within a minibasin, making this a non-structural play. The potential for gas hydrate occurrence at WR313 is supported by shingled phase reversals consistent with the transition from gas-charged sand to overlying gas-hydrate saturated sand. Drilling locations have been selected at each site to 1) test geological methods and models used to infer the occurrence of gas hydrate in sand reservoirs in different settings in the northern Gulf of Mexico; 2) calibrate geophysical models used to detect gas hydrate sands, map reservoir thicknesses, and estimate the degree of gas hydrate saturation; and 3) delineate potential locations for subsequent JIP drilling and coring operations that will collect samples for comprehensive physical property, geochemical and other analyses

BACA Project: geothermal demonstration power plant. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-12-01

The various activities that have been conducted by Union in the Redondo Creek area while attempting to develop the resource for a 50 MW power plant are described. The results of the geologic work, drilling activities and reservoir studies are summarized. In addition, sections discussing the historical costs for Union's involvement with the project, production engineering (for anticipated surface equipment), and environmental work are included. Nineteen geothermal wells have been drilled in the Redondo Creek area of the Valles Caldera: a prominent geologic feature of the Jemez mountains consisting of Pliocene and Pleistocene age volcanics. The Redondo Creek area ismore » within a complex longitudinal graben on the northwest flank of the resurgent structural dome of Redondo Peak and Redondo Border. The major graben faults, with associated fracturing, are geologically plausible candidates for permeable and productive zones in the reservoir. The distribution of such permeable zones is too erratic and the locations too imprecisely known to offer an attractive drilling target. Log analysis indicates there is a preferred mean fracture strike of N31W in the upper portion of Redondo Creek wells. This is approximately perpendicular to the major structure in the area, the northeast-striking Redondo Creek graben. The geothermal fluid found in the Redondo Creek reservoir is relatively benign with low brine concentrations and moderate H/sub 2/S concentrations. Geothermometer calculations indicate that the reservoir temperature generally lies between 500/sup 0/F and 600/sup 0/F, with near wellbore flashing occurring during the majority of the wells' production.« less

Structure and lithology of the Japan Trench subduction plate boundary fault

NASA Astrophysics Data System (ADS)

Kirkpatrick, James D.; Rowe, Christie D.; Ujiie, Kohtaro; Moore, J. Casey; Regalla, Christine; Remitti, Francesca; Toy, Virginia; Wolfson-Schwehr, Monica; Kameda, Jun; Bose, Santanu; Chester, Frederick M.

2015-01-01

The 2011 Mw9.0 Tohoku-oki earthquake ruptured to the trench with maximum coseismic slip located on the shallow portion of the plate boundary fault. To investigate the conditions and physical processes that promoted slip to the trench, Integrated Ocean Drilling Program Expedition 343/343T sailed 1 year after the earthquake and drilled into the plate boundary ˜7 km landward of the trench, in the region of maximum slip. Core analyses show that the plate boundary décollement is localized onto an interval of smectite-rich, pelagic clay. Subsidiary structures are present in both the upper and lower plates, which define a fault zone ˜5-15m thick. Fault rocks recovered from within the clay-rich interval contain a pervasive scaly fabric defined by anastomosing, polished, and lineated surfaces with two predominant orientations. The scaly fabric is crosscut in several places by discrete contacts across which the scaly fabric is truncated and rotated, or different rocks are juxtaposed. These contacts are inferred to be faults. The plate boundary décollement therefore contains structures resulting from both distributed and localized deformation. We infer that the formation of both of these types of structures is controlled by the frictional properties of the clay: the distributed scaly fabric formed at low strain rates associated with velocity-strengthening frictional behavior, and the localized faults formed at high strain rates characterized by velocity-weakening behavior. The presence of multiple discrete faults resulting from seismic slip within the décollement suggests that rupture to the trench may be characteristic of this margin.

In-situ stress and fracture permeability in a fault-hosted geothermal reservoir at Dixie Valley, Nevada

USGS Publications Warehouse

Hickman, Stephen; Barton, Colleen; Zoback, Mark; Morin, Roger; Sass, John; Benoit, Richard; ,

1997-01-01

As part of a study relating fractured rock hydrology to in-situ stress and recent deformation within the Dixie Valley Geothermal Field, borehole televiewer logging and hydraulic fracturing stress measurements were conducted in a 2.7-km-deep geothermal production well (73B-7) drilled into the Stillwater fault zone. Borehole televiewer logs from well 73B-7 show numerous drilling-induced tensile fractures, indicating that the direction of the minimum horizontal principal stress, Shmin, is S57 ??E. As the Stillwater fault at this location dips S50 ??E at approximately 3??, it is nearly at the optimal orientation for normal faulting in the current stress field. Analysis of the hydraulic fracturing data shows that the magnitude of Shmin is 24.1 and 25.9 MPa at 1.7 and 2.5 km, respectively. In addition, analysis of a hydraulic fracturing test from a shallow well 1.5 km northeast of 73B-7 indicates that the magnitude of Shmin is 5.6 MPa at 0.4 km depth. Coulomb failure analysis shows that the magnitude of Shmin in these wells is close to that predicted for incipient normal faulting on the Stillwater and subparallel faults, using coefficients of friction of 0.6-1.0 and estimates of the in-situ fluid pressure and overburden stress. Spinner flowmeter and temperature logs were also acquired in well 73B-7 and were used to identify hydraulically conductive fractures. Comparison of these stress and hydrologic data with fracture orientations from the televiewer log indicates that hydraulically conductive fractures within and adjacent to the Stillwater fault zone are critically stressed, potentially active normal faults in the current west-northwest extensional stress regime at Dixie Valley.

Palaeopermeability anisotropies of a strike-slip fault damage zone: 3D Insights of quantitative fluid flow from µCT analysis.

NASA Astrophysics Data System (ADS)

Gomila, R.; Arancibia, G.; Nehler, M.; Bracke, R.; Morata, D.

2017-12-01

Fault zones and their related structural permeability are a key aspect in the migration of fluids through the continental crust. Therefore, the estimation of the hydraulic properties (palaeopermeability conditions; k) and the spatial distribution of the fracture mesh within the damage zone (DZ) are critical in the assessment of fault zones behavior for fluids. The study of the real spatial distribution of the veinlets of the fracture mesh (3D), feasible with the use of µCT analyses, is a first order factor to unravel both, the real structural permeability conditions of a fault-zone, and the validation of previous (and classical) estimations made in 2D analyses in thin-sections. This work shows the results of a fault-related fracture mesh and its 3D spatial distribution in the damage-zone of the Jorgillo Fault (JF), an ancient subvertical left-lateral strike-slip fault exposed in the Atacama Fault System in northern Chile. The JF is a ca. 20 km long NNW-striking strike-slip fault with sinistral displacement of ca. 4 km. The methodology consisted of drilling 5 mm vertically oriented plugs at several locations within the JF damage zone. Each specimen was scanned with an X-Ray µCT scanner, to assess the fracture mesh, with a voxel resolution of ca. 4.5 µm in the 3D reconstructed data. Tensor permeability modeling, using Lattice-Boltzmann Method, through the segmented microfracture mesh show GMkmin (geometric mean values) of 2.1x10-12 and 9.8x10-13 m2, and GMkmax of 6.4x10-12 and 2.1x10-12 m2. A high degree of anisotropy of the DZ permeability tensor both sides of the JF (eastern and western side, respectively) is observed, where the k values in the kmax plane are 2.4 and 1.9 times higher than the kmin direction at the time of fracture sealing. This style of anisotropy is consistent with the obtained for bedded sandstones supporting the idea that damage zones have an analogous effect - but vertically orientated - on bulk permeability (in low porosity rocks) as stratigraphic layering, where across-strike khorizontal of a fault is lower when compared with the kvertical and kfault parallel. Acknowledgements: This work is a contribution to FONDAP-CONICYT Project 15090013 and CONICYT- BMBF International Scientific Collaborative Research Program Project PCCI130025/FKZ01DN14033. R.G. Ph.D. is funded by CONICYT Scholarship 21140021.

Characterizing the potential for fault reactivation related to CO2 injection through subsurface structural mapping and stress field analysis, Wellington Field, Sumner County, KS

NASA Astrophysics Data System (ADS)

Schwab, D.; Bidgoli, T.; Taylor, M. H.

2015-12-01

South-central Kansas has experienced an unprecedented increase in seismic activity since 2013. The spatial and temporal relationship of the seismicity with brine disposal operations has renewed interest in the role of fluids in fault reactivation. This study focuses on determining the suitability of CO2 injection into a Cambro-Ordovician reservoir for long-term storage and a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. Our approach for determining the potential for induced seismicity has been to (1) map subsurface faults and estimate in-situ stresses, (2) perform slip and dilation tendency analysis to identify optimally-oriented faults relative to the estimated stress field, and (3) monitor surface deformation through cGPS data and InSAR imaging. Through the use of 3D seismic reflection data, 60 near vertical, NNE-striking faults have been identified. The faults range in length from 140-410 m and have vertical separations of 3-32m. A number of faults appear to be restricted to shallow intervals, while others clearly cut the top basement reflector. Drilling-induced tensile fractures (N=78) identified from image logs and inversion of earthquake focal mechanism solutions (N=54) are consistent with the maximum horizontal stress (SHmax) oriented ~E-W. Both strike-slip and normal-slip fault plane solutions for earthquakes near the study area suggest that SHmax and Sv may be similar in magnitude. Estimates of stress magnitudes using step rate tests (Shmin = 2666 psi), density logs (Sv = 5308 psi), and calculations from wells with drilling induced tensile fractures (SHmax = 4547-6655 psi) are determined at the gauge depth of 4869ft. Preliminary slip and dilation tendency analysis indicates that faults striking 0°-20° are stable, whereas faults striking 26°-44° may have a moderate risk for reactivation with increasing pore-fluid pressure.

The ML 3.5 earthquake sequence induced by the hydrothermal energy project in St. Gallen, Switzerland

NASA Astrophysics Data System (ADS)

Kraft, T.; Wiemer, S.; Deichmann, N.; Diehl, T.; Edwards, B.; Guilhem, A.; Haslinger, F.; Király, E.; Kissling, E. H.; Mignan, A.; Plenkers, K.; Roten, D.; Seif, S.; Woessner, J.

2013-12-01

Starting in March 2013, the geothermal project of the city of Sankt Gallen, Switzerland, has drilled through 4 km of sedimentary rocks in the Swiss Molasse Basinin order to find and exploit hydrothermal aquifers in the Mesozoic sediments. In a large-scale 3D seismic survey, the project operators identified a nearly 30 km long N-S striking segmented fault zone in the Mesozoic sediments. Based on the apparent lack of recent seismic activity, they concluded that the fault zone was not active and drilled into this target of potentially enhanced permeability. In July 2013 a testing and stimulation program began in the Malm sediments. A small-scale fresh water injectionon July 14 was followed by two acid stimulations. A low level of seismicity that strongly correlated with the testing program was observed by the Swiss Seismological Service (SED) on a dedicated network of 10 surface stations and one shallow borehole station. The seismicity during this period did not exceed magnitude ML1.2 and was judged to be well within the expected range. When operators were preparing for an airlift test, methane gas was released into the borehole from an unknown source around noon on July 19. The pressure at the wellhead rose rapidly, and operators decided to pump water and heavy mud down the well. Even though wellhead pressure decreased steadily, seismicity started to increase suddenly at 7 pm (UTC) on July 19. Although the traffic light system designed by the operators was triggered in the early phase of the seismicity increase, operators found themselves forced to continue well control instead of stopping the pumps. During this period, the seismicity intensified and culminated in a ML 3.5 event at 3:30 (UTC) on July 20 that was widely felt in the area. Yet, the SED received only a small number of reports on minor non-structural damage. In the following hours, the operators were able to stabilize the well and flare the methane in a controlled manner. Seismicity decreased rapidly within a few days but two weeks later was still far from reaching the background level. Here we report on the results of our analysis of the induced seismic sequence at Sankt Gallen: ML 3.5 event initiated near the borehole, had a comparatively low stress drop (3.5 bar) and a rupture length of ~1.1 km. Peak ground motions observed for the ML 3.5 eventare very similar to the ones observed in the ML 3.4 event induced in 2006 in Basel. Yet, macroseismic intensities in St. Gallen only reach IV (EMS) versus V (EMS) in Basel. Precise earthquake relative locations indicate that seismicity extends bi-laterally from the injection point, following the trend of the mapped fault segments. Fault plane solutions of the two largest events indicate a left lateral strike slip fault whose orientation agrees well with the aftershock locations and the imaged fault zone. The St. Gallen sequence shows the highest seismic productivity per injected fluid volume when compared to other injection-induced sequences, and challenges proposed relations between injected fluid volume and maximum observed magnitude or between hydraulic energy and released seismic energy.

The characteristics of heat flow in the Shenhu gas hydrate drilling area, northern South China Sea

NASA Astrophysics Data System (ADS)

Xu, Xing; Wan, Zhifeng; Wang, Xianqing; Sun, Yuefeng; Xia, Bin

2016-12-01

Marine heat flow is of great significance for the formation and occurrence of seabed oil, gas and gas hydrate resources. Geothermal gradient is an important parameter in determining the thickness of the hydrate stability zone. The northern slope of the South China Sea is rich in gas hydrate resources. Several borehole drilling attempts were successful in finding hydrates in the Shenhu area, while others were not. The failures demand further study on the distribution regularities of heat flow and its controlling effects on hydrate occurrence. In this study, forty-eight heat flow measurements are analyzed in the Shenhu gas hydrate drilling area, located in the northern South China Sea, together with their relationship to topography, sedimentary environment and tectonic setting. Canyons are well developed in the study area, caused mainly by the development of faults, faster sediment supply and slumping of the Pearl River Estuary since the late Miocene in the northern South China Sea. The heat flow values in grooves, occurring always in fault zones, are higher than those of ridges. Additionally, the heat flow values gradually increase from the inner fan, to the middle fan, to the external fan subfacies. The locations with low heat flow such as ridges, locations away from faults and the middle fan subfacies, are more conducive to gas hydrate occurrence.

Play-fairway analysis for geothermal exploration: Examples from the Great Basin, western USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siler, Drew L; Faulds, James E

2013-10-27

Elevated permeability within fault systems provides pathways for circulation of geothermal fluids. Future geothermal development depends on precise and accurate location of such fluid flow pathways in order to both accurately assess geothermal resource potential and increase drilling success rates. The collocation of geologic characteristics that promote permeability in a given geothermal system define the geothermal ‘fairway’, the location(s) where upflow zones are probable and where exploration efforts including drilling should be focused. We define the geothermal fairway as the collocation of 1) fault zones that are ideally oriented for slip or dilation under ambient stress conditions, 2) areas withmore » a high spatial density of fault intersections, and 3) lithologies capable of supporting dense interconnected fracture networks. Areas in which these characteristics are concomitant with both elevated temperature and fluids are probable upflow zones where economic-scale, sustainable temperatures and flow rates are most likely to occur. Employing a variety of surface and subsurface data sets, we test this ‘play-fairway’ exploration methodology on two Great Basin geothermal systems, the actively producing Brady’s geothermal system and a ‘greenfield’ geothermal prospect at Astor Pass, NV. These analyses, based on 3D structural and stratigraphic framework models, reveal subsurface characteristics about each system, well beyond the scope of standard exploration methods. At Brady’s, the geothermal fairways we define correlate well with successful production wells and pinpoint several drilling targets for maintaining or expanding production in the field. In addition, hot-dry wells within the Brady’s geothermal field lie outside our defined geothermal fairways. At Astor Pass, our play-fairway analysis provides for a data-based conceptual model of fluid flow within the geothermal system and indicates several targets for exploration drilling.« less

Heat flow pattern in the gas hydrate drilling areas of northern south china sea and the implication for further study

NASA Astrophysics Data System (ADS)

Wang, Lifeng; Sha, Zhibin

2015-04-01

Numerous seismic reflection profiles have been acquired by China Geological Survey (CGS) in the Northern Slope of South China Sea (SCS), clearly indicating widespread occurrence of free gases and/or gas hydrates in the sediments. In the year 2007 and 2013 respectively the gas hydrate samples are successfully recovered during two offshore drilling exploratory programs. Results of geothermal data during previous field studies along the north continental margin, however, show that the gas hydrate sites are associated with high geothermal background in contrast to the other offshore ones where the gas hydrates are more likely to be found in the low geothermal regional backgrounds. There is a common interesting heat flow pattern during the two drilling expeditions that the gas hydrate occurrences coincide with the presences of comparatively low geothermal anomalies against the high thermal background which is mainly caused by concentrated fluid upward movements into the stability zone (GHSZ) detected by the surface heat flow measurements over the studied fields. The key point for understanding the coupling between the presences of the gas hydrates and heat flow pattern at regional scale is to know the cause of high heat flows and the origin of forming gases at depth. We propose that these high heat flows are attributed to elevated shallow fault-fissure system due to the tectonic activities. A remarkable series of vertical faults and fissures are common on the upper continental slope and the forming gases are thought to have migrated with hot advective fluid flows towards seafloor mainly via fault-fissure system from underlying source rocks which are deeper levels than those of the GHSZ. The present study is based on an extensive dataset on hydrate distribution and associated temperature field measurements collected in the vicinity of studied areas during a series of field expeditions organized within the framework of national widely collaborative projects. Those observations bring new insights to our growing understanding of the stability of this dynamic hydrate reservoir in the continental margin shallow subsurface, and alert us that occurrence patterns may be more complex than previously thought. So the future aim of this program is to better understand the factors constraining the distribution of hydrate deposits, and the processes involved in gas hydrate formation.

Structural and Lithologic Characterization of the SAFOD Pilot Hole and Phase One Main Hole

NASA Astrophysics Data System (ADS)

Barton, D. C.; Bradbury, K.; Solum, J. G.; Evans, J. P.

2005-12-01

Petrological and microstructural analyses of drill cuttings were conducted for the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole and Main Hole projects. Grain mounts were produced at ~30 m (100 ft) intervals from drill cuttings collected from the Pilot Hole to a depth of 2164 m (7100 ft) and from Phase 1 of the SAFOD main hole to a depth of 3067 m (10062 ft). . Thin-section grain mount analysis included identification of mineral composition, alteration, and deformation within individual grains, measured at .5 mm increments on an equally spaced, 300 point grid pattern. Lithologic features in the Quaternary/Tertiary deposits from 30 - 640 m (100-2100 ft) in the Pilot Hole, and 670 - 792 m (2200 - 2600 ft) in the Phase 1 main hole, include fine-grained, thinly bedded sediments with clasts of fine-grained volcanic groundmass. Preliminary grain mount analysis from 1920 - 3067 m (6300 - 10062) in the Phase 1 main hole, indicates a sedimentary sequence consisting of fine-grained lithic fragments of very fine-grained shale. Deformation mechanisms observed within the cuttings of granitic rocks from 914 - 1860 m (3000 - 6100 ft.) include intracrystalline plasticity and cataclasis. Intracrystalline plastic deformation within quartz and feldspar grains is indicated by undulatory extinction, ribbon grains, chessboard patterns, and deformation twins and lamellae. Cataclastic deformation is characterized by intra- and intergranular microfractures, angular grains, gouge zones, iron-oxide banding, and comminution. Mineral and cataclasite abundances were plotted as a function of weight percent vs. depth. Plots of quartz and feldspar abundances are also correlated with XRD weight percent data from 1160 - 1890 m (3800 - 6200 ft.) in the granitic and granodioritic sequences of the Phase 1 main hole. Regions of the both of the drill holes with cataclasite abundances ranging from 20 - 30 wt% are interpreted as shear zones. Shear zones identified in this study from 1150 - 1420 m (3773 - 4659 ft.) in the Pilot Hole occur in the same location as shear zones recognized by Boness and Zoback (2004) using borehole geophysical data. These shear zones may possibly be correlated to shear zones identified in the Phase I main hole from 1615 - 2012 m (5300 - 6600 ft). If this is the case, it can be explained by steeply dipping subsidiary fault zones, likely associated with the San Andreas Fault system.

Probabilistic Risk Assessment of Hydraulic Fracturing in Unconventional Reservoirs by Means of Fault Tree Analysis: An Initial Discussion

NASA Astrophysics Data System (ADS)

Rodak, C. M.; McHugh, R.; Wei, X.

2016-12-01

The development and combination of horizontal drilling and hydraulic fracturing has unlocked unconventional hydrocarbon reserves around the globe. These advances have triggered a number of concerns regarding aquifer contamination and over-exploitation, leading to scientific studies investigating potential risks posed by directional hydraulic fracturing activities. These studies, balanced with potential economic benefits of energy production, are a crucial source of information for communities considering the development of unconventional reservoirs. However, probabilistic quantification of the overall risk posed by hydraulic fracturing at the system level are rare. Here we present the concept of fault tree analysis to determine the overall probability of groundwater contamination or over-exploitation, broadly referred to as the probability of failure. The potential utility of fault tree analysis for the quantification and communication of risks is approached with a general application. However, the fault tree design is robust and can handle various combinations of regional-specific data pertaining to relevant spatial scales, geological conditions, and industry practices where available. All available data are grouped into quantity and quality-based impacts and sub-divided based on the stage of the hydraulic fracturing process in which the data is relevant as described by the USEPA. Each stage is broken down into the unique basic events required for failure; for example, to quantify the risk of an on-site spill we must consider the likelihood, magnitude, composition, and subsurface transport of the spill. The structure of the fault tree described above can be used to render a highly complex system of variables into a straightforward equation for risk calculation based on Boolean logic. This project shows the utility of fault tree analysis for the visual communication of the potential risks of hydraulic fracturing activities on groundwater resources.

Crustal Structure and Seismicity along the Central Alpine Fault: Results from the WIZARD Array

NASA Astrophysics Data System (ADS)

Thurber, C. H.; Roecker, S. W.; Townend, J.; Bannister, S. C.; Guo, B.; Rawles, C.; Feenstra, J. P.

2015-12-01

In 2012 and 2013, the University of Wisconsin-Madison (UW), Rensselaer Polytechnic Institute (RPI), and Victoria University of Wellington (VUW) operated a 20-station temporary seismic array along the obliquely slipping Alpine Fault on the South Island of New Zealand. The stations of the array, nicknamed WIZARD, were deployed mainly north and east of the Deep Fault Drilling Program (DFDP) borehole site in Whataroa Valley (DFPD-2). WIZARD complemented the station distribution of the Southern Alps Microearthquake Borehole Array (SAMBA) operated by VUW, situated south and west of DFDP-2. Three additional temporary stations were deployed to the north and east of WIZARD by GNS Science, and four GeoNet permanent stations fell within the footprint of our study area. The main goals of the WIZARD project are to image the crustal structure in the region surrounding the DFDP-2 site, relocate earthquakes as precisely and accurately as possible, and determine focal mechanisms for the larger earthquakes, in order to characterize the Alpine Fault and its geometry at depth. Some previous studies had identified the area covered by WIZARD to be largely aseismic, but we have in fact located roughly 500 earthquakes underneath WIZARD. A new automatic S-wave picker proved to be very effective for rapidly increasing the size of our S-wave arrival dataset. Our tomographic inversion results show that significant velocity contrasts in both Vp and Vs (hanging wall fast) appear to delineate the Alpine Fault at depth in most of our study region, dipping typically about 60 degrees SE, and some focal mechanisms show oblique slip. However, we are not able to identify earthquakes that are actually occurring on the Alpine Fault with certainty based only on our location results.

Regional distribution of volcaniclastic layer and its implication for segmentation of the Nankai seismogenic zone

NASA Astrophysics Data System (ADS)

Sasaki, T.; Lim, J.; Higashi, M.; Park, J.

2010-12-01

The Nankai Trough is known as one of the best-suited convergent plate margins for studying accretionary prism growth as well as subduction zone earthquakes. Along the Nankai accretionary margin off southwest Japan, the Shikoku Basin which formed 26-15 Ma as backarc spreading in the Philippine Sea Plate is being subducted about 4 cm/year to the northwest. The Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) penetrated the Nankai accretionary prism and the incoming sedimentary section along the Ashizuri and Muroto transects, off Shikoku Island. Also, Integrated Ocean Drilling Program (IODP), which represented just one part of a multi-stage project known as the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) has been conducting drilling cruises now. IODP Expedition 322 in 2009, the coring was carried out at two drilling sites on the northern part of the Shikoku Basin in the subducting Philippine Sea plate. One of the major achievements of Expedition 322 is a discovery of late Miocene (10.2-7.6 Ma) tuffaceous and volcaniclastic sandstone layer (Underwood et al., IODP Prel. Rept. 322, 2009) that has not been previously recognized in the Nankai Trough. Based on age and volcanic sand content analysis, these volcaniclastic layers were unique to the Shikoku Basin off Kii Peninsula. The closest source of this volcanic layer was supposed to be the Izu-Bonin arc. Subducted sediments ultimately affect subduction zone geochemistry, thermal structure, and seismogenesis. High porosity of the volcaniclastic sandstone layer suggests the transportation of fluid to the subduction zone, it might affect the initiation and evolution of the decollement zone or plate boundary fault in the Nankai Trough. We interpreted single channel and multichannel seismic reflection profiles that have been acquired in the Nankai Trough margin by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) since the year of 1997. We tried to map the major seismic layers such as volcaniclastic layer, volcanic ash layer and turbidite layers which were found at drilling sites in the IODP Expedition 322 in the northern Shikoku Basin. As a result, we recognized that these prominent seismic layers are widely distributed in the northern Shikoku Basin. In this talk, we will show specific seismic layers directly connecting to the decollement at the Nankai Trough axis, and discuss its implications for subduction processes in the Nankai Trough margin.

The effect of the Baton Rouge fault on flow in the Abita aquifer of southeastern Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, T.R.

1993-03-01

The ground-water resources of southern Tangipahoa Parish and adjacent areas were studied to determine their potential for development as an alternative to the Mississippi River as a water supply source for Jefferson Parish, Louisiana. The study area, in southeastern Louisiana, is underlain by eight major aquifers and is crossed by a fault zone, referred to as the Baton Rouge fault. The fault restricts the flow of water in the aquifers of intermediate depth. Data from a test well drilling program and geophysical logs of a nearby oil well indicated that a significant freshwater aquifer that provides water to a nearbymore » municipality was actually the Abita aquifer and not the Covington aquifer, as was previously thought. The Abita aquifer, a shallower aquifer with a lower hydraulic conductivity, had been displaced to a position equivalent to that of the Covington aquifer by the Baton Rouge fault. An additional final test well drilled south of the fault penetrated the leading edge of a wedge-shaped saltwater interface. Analysis of lithologic and geophysical logs indicated that the Abita aquifer has a well-sorted, clean sand at the base of the aquifer and substantial amounts of clay in the top two-thirds of the aquifer. Geophysical logs of oil test wells south of the fault zone indicated that the sand thickens substantially to the south. The thicker sand south of a public supply well that pumps water from the Abita aquifer and the higher hydraulic conductivity of the lower part of the aquifer where the saline water was detected indicate that a much larger percentage of recharge to the public supply well may come from the south than was originally thought.« less

Frictional properties of Alpine Fault gouge in high-velocity shear experiments

NASA Astrophysics Data System (ADS)

Morgan, C.; Reches, Z.

2015-12-01

The Alpine Fault, New Zealand, is a plate boundary with slip rate of ~ 37 mm/yr, with major historic seismic events. The Deep Fault Drilling Program (DFDP) into the Alpine Fault had two phases in 2011 and 2014, with main objectives of fault-zone sampling and borehole instrumentations. As complementary work to the drilling, we analyze the frictional properties of the Alpine Fault gauge on samples collected at three field exposures (Waikukupa, Cataclasite, and Gaunt) at distances up to 70 km away from DFDP-2. The bulk samples (1-3 kg) were first manually disintegrated without shear, and then sieved to the 250-350 micron fraction. The gouge was sheared in a Confined Rotary Cell (CROC) in the natural, moisture conditions, at slip-velocity range of 0.01 m/s to 0.5 m/s (constant and stepped) with a constant normal stress of 2-3 MPa. Runs included monitoring the CO2 and H2O emission, in addition to the standard mechanical parameters. The preliminary results show an initial friction coefficient ~0.6. Initial slip at low velocities (0.01 m/s) display gentle velocity strengthening, that changed to a drastic weakening (~50%) at velocity of 0.5 m/s. This weakening was associated with intense slip localization along a hard, dark slip surface within the gouge zone. After the establishment of this slip surface, the low friction remains for the following low slip-velocity steps. Future work will include: (1) systematic investigation of the dynamic friction dependence on the slip-velocity and slip-distance; (2) analysis of the relations between friction, mineralogy and the release of CO2/H2O; and (3) application of the experimental results to characterize natural fault behavior.

Postglacial seismic activity along the Isovaara-Riikonkumpu fault complex

NASA Astrophysics Data System (ADS)

Ojala, Antti E. K.; Mattila, Jussi; Ruskeeniemi, Timo; Palmu, Jukka-Pekka; Lindberg, Antero; Hänninen, Pekka; Sutinen, Raimo

2017-10-01

Analysis of airborne LiDAR-based digital elevation models (DEMs), trenching of Quaternary deposits, and diamond drilling through faulted bedrock was conducted to characterize the geological structure and full slip profiles of the Isovaara-Riikonkumpu postglacial fault (PGF) complex in northern Finland. The PGF systems are recognized from LiDAR DEMs as a complex of surface ruptures striking SW-NE, cutting through late-Weichselian till, and associated with several postglacial landslides within 10 km. Evidence from the terrain rupture characteristics, the deformed and folded structure of late-Weichselian till, and the 14C age of 11,300 cal BP from buried organic matter underneath the Sotka landslide indicates a postglacial origin of the Riikonkumpu fault (PGF). The fracture frequency and lithology of drill cores and fault geometry in the trench log indicate that the Riikonkumpu PGF dips to WNW with a dip angle of 40-45° at the Riikonkumpu site and close to 60° at the Riikonvaara site. A fault length of 19 km and the mean and maximum cumulative vertical displacement of 1.3 m and 4.1 m, respectively, of the Riikonkumpu PGF system indicate that the fault potentially hosted an earthquake with a moment magnitude MW ≈ 6.7-7.3 assuming that slip was accumulated in one seismic event. Our interpretation further suggests that the Riikonkumpu PGF system is linked to the Isovaara PGF system and that, together, they form a larger Isovaara-Riikonkumpu fault complex. Relationships between the 38-km-long rupture of the Isovaara-Riikonkumpu complex and the fault offset parameters, with cumulative displacement of 1.5 and 8.3 m, respectively, indicate that the earthquake(s) contributing to the PGF complex potentially had a moment magnitude of MW ≈ 6.9-7.5. In order to adequately sample the uncertainty space, the moment magnitude was also estimated for each major segment within the Isovaara-Riikonkumpu PGF complex. These estimates vary roughly between MW ≈ 5-8 for the individual segments.

Enhanced Geothermal Systems (EGS) - Where Are We Now

NASA Astrophysics Data System (ADS)

Wyborn, D.

2011-12-01

There were seven major EGS projects in which reservoir circulation was achieved prior to the Geodynamics Limited project in the Innamincka granite in northern South Australia which commenced in 2002. Six other projects did not achieve significant circulation. Importantly all but one of these projects were located in granitic bodies in which it is assumed that families of existing natural fractures are present. Evidence from all these EGS projects indicated that: 1 Stimulation in granite rock resulting from water injection with no added chemicals enhanced rock fracture permeability by 2-3 orders of magnitude. 2 The increased permeability resulted from increased fracture porosity associated with slippage on existing natural fractures during the stimulation. 3The extent of the resulting reservoir could be accurately mapped by acoustic (micro-seismic) monitoring of the fracture slippages. 4 The orientation of the reservoir is strongly dependent on the relative directions of the three principle rock stress axes. 5 The stimulation pumping pressures required were 50-75% of the minimum principle stress for the depth of reservoir creation in accord with geomechanical theory, and are therefore lower than those required to open tensile fractures (fracking). 6 The size of the resulting stimulated reservoir is proportional to the volume of water injected. New space created by the increase in fracture porosity associated with the micro-seismic events is taken up by the injected water. 7 Most projects to 2002 were carried out in strike-slip and normal faulting stress regimes with minimum stress direction horizontal and the resulting reservoirs were oriented close to vertically. 8 Volcanic activity can only occur in strike-slip and normal faulting stress regimes so EGS reservoirs in volcanic areas will be oriented close to vertically. 9 The Fjallbacka project in Sweden was the only project carried out in an overthrust stress regime (minimum stress direction vertical) and the reservoir was oriented horizontally. It is with these understandings that the Geodynamics field program commenced near Innamincka in 2002 where high temperature granite basement had been intersected at 3.6 km depth by petroleum exploration wells. Gravity and heat flow models indicated the basement granite to be 10 km thick and that most of the heat flow (> 100 mW/m2) was derived from elevated thorium and uranium levels in the granite. The stress environment was thought to be overthrust, but this was not certain.The results of the Geodynamics field program consists of drilling 5 wells to the granite, stimulation in three of those wells, flow testing in two of those wells and circulation between two of those wells. There are now four main barriers to economic deployment of EGS throughout the world for electricity generation. One is the cost of drilling and new technologies need to be developed to increase drilling ROP in high strength rocks. The other three relate to reservoir development and increased flow rate. These are (i) new geophysical tools to locate large fractures remotely (ii) deployment of temporary fracture sealing agents to allow enhancement in more than one fracture, and (iii) decreased flow impedance in a given fracture at the production well. New projects at different locations around the world are required to test ways of overcoming these barriers.

An interdisciplinary approach to reservoir management: The Malu Field, West Niger Delta, Nigeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, B.A.; Bluhm, C.T.; Adokpaye, E.U.

The Malu Field is 175 kilometers southeast of Lagos, offshore Nigeria. The field was discovered in 1967 and brought on stream in 1971. Peak production reached 31,300 barrels per day in 1972. Twenty-six wells have been drilled in the thirty-six square kilometer size field. In 1990 original-oil-in-place was estimated at 345 million barrels with cumulative production of 109 million barrels and an estimated 40 million barrels of remaining reserves. The Main Field review was initiated in 1994 to resolve structural and production inconsistencies and therefore improve reservoir performance. The tools used include reprocessed three-dimensional seismic, oil chemistry (primarily gas chromatography),more » and production data. The complexly faulted field is subdivided into seven different fault blocks. Growth faults generally trend northwest to southeast and are downthrown to the west. Twenty-five different hydrocarbon-bearing sands have been identified within the field. These sands are separated into sixty-three different reservoirs by the series of southeast trending growth faults. Most sands are laterally continuous within mapped fault blocks except in east Malu. Cross-fault communication of oils occurs among several of the shallow reservoirs in west Malu allowing wells to deplete unintended horizons. In addition, three of the dual string completions are producing oil only from only the upper sands. The integration of seismic, oil chemistry, and production data allows more efficient management of production by providing accurate structure maps, reserve estimates, drainage pathways, and justification for workovers and future development drilling.« less

Noise Configuration and fault zone anisotropy investigation from Taiwan Chelungpu-fault Deep Borehole Array

NASA Astrophysics Data System (ADS)

Hung, R. J.; Ma, K. F.; Song, T. R. A.; Nishida, K.; Lin, Y. Y.

2016-12-01

The Taiwan Chelungpu-fault Drilling Project was operated to understand the fault zone characteristics associated with the 1999 Chichi earthquake. Seven Borehole Seismometers (TCDPBHS) were installed through the identified fault zone to monitor the micro-seismic activities, as well as the fault-zone seismic structure properties. To understand the fault zone anisotropy and its possible temporal variations after the Chichi earthquake, we calculated cross-correlations of the noise at different stations to obtain cross correlation functions (CCFs) of the ambient noise field between every pair of the stations. The result shows that TCDP well site suffers from complex wavefield, and phase traveltime from CCF can't provide explicit result to determine the dominated wavefield. We first analyze the power density spectra and probability density functions of this array. We observe that the spectra show diurnal variation in the frequency band 1-25 Hz, suggesting human-generated sources are dominated in this frequency band. Then, we focus on the particle motion analysis at each CCF. We assume one component at a station plays as a visual source and compute the CCF tensor in other station components. The particle motion traces show high linearity which indicate that the dominated wavefield in our study area is body wave signals with the azimuth approximate to 60° from north. We also analyze the Fourier spectral amplitudes by rotating every 5 degrees in time domain to search for the maximum background energy distribution. The result shows that the spectral amplitudes are stronger at NE-SW direction, with shallow incident angles which are comparable with the CCF particle motion measurement. In order to obtain higher resolution about the dominated wavefield in our study area, we also used beamforming from surface station array to validate our results from CCF analysis. In addition to the CCF analysis to provide the noise configuration at the TCDPBHS site for further analysis on fault zone anisotropy using ambient noise, we also analyze fault zone anisotropy using the events data recorded by TCDPBHS. The identified event clusters through the borehole data enhance the consistency in results to give hints on fault zone anisotropy.

In-situ stress measurements using core-based methods in the vicinity of Nojima fault.

NASA Astrophysics Data System (ADS)

Yano, S.; Sugimoto, T.; Lin, W.; Lin, A.

2017-12-01

In the cycle of repeatable occurrence of earthquakes, stress accumulates at the source fault and its surroundings in an interseismic period until the next earthquake, and releases abruptly when the earthquake occurs. However, it is almost unknown that the quantitative relationship between stress change and earthquake occurrence. Hence, in order to improve our understanding on the mechanisms of the outbreak of earthquakes, it is important to grasp the stress states in the vicinity of the source fault and to evaluate its change over time. In this study, we carried out in-situ stress measurements by using core samples obtained from a scientific drilling penetrated through the Nojima fault which ruptured and caused the Hyogo-ken Nanbu earthquake, Japan in 1995. Our stress measurements were conducted from 2016 to 2017 when is 22 years after the earthquake. For this purpose, we applied the Anelastic Strain Recovery (ASR) method and Diametrical Core Deformation Analysis (DCDA). First, we measure the ASR change with time of the cores from stress releasing soon and calculate three-dimensional principal in-situ stress orientations and magnitudes from the ASR data. In this study, to ensure the enough amount of ASR, we conducted the measurements using the cores collected within a short time (e.g. 2.5 - 3.5 hours) after stress releasing by drilling at an on-site laboratory in the drilling site in Awaji island, Japan. The site locates at the south-west part of the Nojima fault. In DCDA, we measure the core diameters in all (360°) azimuths, and determine difference of the two horizontal principal stresses and their orientation by using the other cores as those used for ASR. DCDA experiments were conducted indoor and after a long time passed from core collecting. Lithology of all the core samples we used for ASR and DCDA are granite, and 19 and 7 cores were used for ASR and DCDA, respectively. As a result, it was found that the stress state in the depth range of 500 - 560 m and around 822 m were of normal faulting stress regime and that in 711 - 730 m was strike slip faulting type. As mentioned above, we have obtained a data set of the current state of stress around Nojima fault using the two core-based stress measurement methods. In future, we will determine the core orientations and restore the directions of the principal stress axes to the geologic coodinates.

Initial Results of Gulf of Mexico Gas Hydrate Joint Industry Program Leg II Logging-While-Drilling Operations in Green Canyon Block 955

NASA Astrophysics Data System (ADS)

McConnell, D. R.; Boswell, R. M.; Collett, T. S.; Frye, M.; Shedd, W.; Mrozewski, S.; Guerin, G.; Cook, A.; Shelander, D.; Dai, J.; Dufrene, R.; Godfriaux, P. D.; Roy, R.; Jones, E.

2009-12-01

The Gulf of Mexico gas hydrates Joint Industry Project (the JIP), a cooperative research program between the US Department of Energy and an international industrial consortium under the leadership of Chevron, conducted its “Leg II” logging-while-drilling operations in April and May of 2009. GC 955 was one of three sites drilled during Leg II. Three holes were drilled at the GC 955 site. High-saturations of gas hydrate in sands were logged at two of the three holes. The gas hydrate targets at the GC 955 site are just basinward of the Sigsbee Escarpment and outboard of the Green Canyon embayment in a Late Pleistocene Mississippi Fan channel levee sequence (0.5Ma). At the GC 955 site, the sand prone channel levee sediments are uplifted by a salt diapir, faulting the channel levee facies as well as focusing hydrocarbon charge to them. The top of the channel is approximately 1000 ft below seafloor and the sand-prone interval is in excess of 700 ft thick. The site was prospective for gas hydrate primarily due to the observation that seismic indicators of gas charge terminated anomalously within the inferred sand interval along a horizon consistent with the base of gas hydrate stability. Seismic amplitude analysis, as well as rock-physics based inversions of the seismic data, were used to refine the potential high-saturation targets. The gas hydrate targets clustered within a four-way closure caused by salt uplift. Other targets, faulted, with evidence of fluid migration, were identified, on the periphery of the closure. Three holes, locations I, H, and Q, were drilled at site GC955. The data acquired consist of a comprehensive suite of high resolution LWD logs including gamma ray, density, porosity, sonic, and resistivity tools. No physical samples were taken in the field. At the I location, only four feet of pore fill gas hydrate was detected within the sandy reservoir facies. At the H location, gas hydrate in clays and thin sands was found above the target zone and 101 ft of high-saturation gas hydrate was found at the primary target. At the Q location, at least 53 ft of high-saturation gas hydrate was found at the primary target before drilling was aborted. The discovery of thick, highly saturated gas hydrate sands at the GC955 site validates that gas hydrate can be found in reservoir quality sands through the integration of geologic and geophysical data. The LWD acquired data provided unprecedented information on the nature of the sediments and the occurrence of gas hydrate in the Gulf of Mexico.

Cenozoic sedimentation in the Mumbai Offshore Basin: Implications for tectonic evolution of the western continental margin of India

NASA Astrophysics Data System (ADS)

Nair, Nisha; Pandey, Dhananjai K.

2018-02-01

Interpretation of multichannel seismic reflection data along the Mumbai Offshore Basin (MOB) revealed the tectonic processes that led to the development of sedimentary basins during Cenozoic evolution. Structural interpretation along three selected MCS profiles from MOB revealed seven major sedimentary sequences (∼3.0 s TWT, thick) and the associated complex fault patterns. These stratigraphic sequences are interpreted to host detritus of syn- to post rift events during rift-drift process. The acoustic basement appeared to be faulted with interspaced intrusive bodies. The sections also depicted the presence of slumping of sediments, subsidence, marginal basins, rollover anticlines, mud diapirs etc accompanied by normal to thrust faults related to recent tectonics. Presence of upthrusts in the slope region marks the locations of local compression during collision. Forward gravity modeling constrained with results from seismic and drill results, revealed that the crustal structure beneath the MOB has undergone an extensional type tectonics intruded with intrusive bodies. Results from the seismo-gravity modeling in association with litholog data from drilled wells from the western continental margin of India (WCMI) are presented here.

Geometry of the Nojima fault at Nojima-Hirabayashi, Japan - I. A simple damage structure inferred from borehole core permeability

USGS Publications Warehouse

Lockner, David A.; Tanaka, Hidemi; Ito, Hisao; Ikeda, Ryuji; Omura, Kentaro; Naka, Hisanobu

2009-01-01

The 1995 Kobe (Hyogo-ken Nanbu) earthquake, M = 7.2, ruptured the Nojima fault in southwest Japan. We have studied core samples taken from two scientific drillholes that crossed the fault zone SW of the epicentral region on Awaji Island. The shallower hole, drilled by the Geological Survey of Japan (GSJ), was started 75 m to the SE of the surface trace of the Nojima fault and crossed the fault at a depth of 624 m. A deeper hole, drilled by the National Research Institute for Earth Science and Disaster Prevention (NIED) was started 302 m to the SE of the fault and crossed fault strands below a depth of 1140 m. We have measured strength and matrix permeability of core samples taken from these two drillholes. We find a strong correlation between permeability and proximity to the fault zone shear axes. The half-width of the high permeability zone (approximately 15 to 25 m) is in good agreement with the fault zone width inferred from trapped seismic wave analysis and other evidence. The fault zone core or shear axis contains clays with permeabilities of approximately 0.1 to 1 microdarcy at 50 MPa effective confining pressure (10 to 30 microdarcy at in situ pressures). Within a few meters of the fault zone core, the rock is highly fractured but has sustained little net shear. Matrix permeability of this zone is approximately 30 to 60 microdarcy at 50 MPa effective confining pressure (300 to 1000 microdarcy at in situ pressures). Outside this damage zone, matrix permeability drops below 0.01 microdarcy. The clay-rich core material has the lowest strength with a coefficient of friction of approximately 0.55. Shear strength increases with distance from the shear axis. These permeability and strength observations reveal a simple fault zone structure with a relatively weak fine-grained core surrounded by a damage zone of fractured rock. In this case, the damage zone will act as a high-permeability conduit for vertical and horizontal flow in the plane of the fault. The fine-grained core region, however, will impede fluid flow across the fault.

18 CFR 430.11 - Advance notice of exploratory drilling.

Code of Federal Regulations, 2010 CFR

2010-04-01

... exploratory drilling. 430.11 Section 430.11 Conservation of Power and Water Resources DELAWARE RIVER BASIN... exploratory drilling. The Commission encourages consultation with any project sponsor who is considering... project and prior to initiation of exploratory drilling. (a) Any person, firm corporation or other entity...

18 CFR 430.11 - Advance notice of exploratory drilling.

Code of Federal Regulations, 2011 CFR

2011-04-01

... exploratory drilling. 430.11 Section 430.11 Conservation of Power and Water Resources DELAWARE RIVER BASIN... exploratory drilling. The Commission encourages consultation with any project sponsor who is considering... project and prior to initiation of exploratory drilling. (a) Any person, firm corporation or other entity...

18 CFR 430.11 - Advance notice of exploratory drilling.

Code of Federal Regulations, 2013 CFR

2013-04-01

... exploratory drilling. 430.11 Section 430.11 Conservation of Power and Water Resources DELAWARE RIVER BASIN... exploratory drilling. The Commission encourages consultation with any project sponsor who is considering... project and prior to initiation of exploratory drilling. (a) Any person, firm corporation or other entity...

18 CFR 430.11 - Advance notice of exploratory drilling.

Code of Federal Regulations, 2012 CFR

2012-04-01

... exploratory drilling. 430.11 Section 430.11 Conservation of Power and Water Resources DELAWARE RIVER BASIN... exploratory drilling. The Commission encourages consultation with any project sponsor who is considering... project and prior to initiation of exploratory drilling. (a) Any person, firm corporation or other entity...

18 CFR 430.11 - Advance notice of exploratory drilling.

Code of Federal Regulations, 2014 CFR

2014-04-01

... exploratory drilling. 430.11 Section 430.11 Conservation of Power and Water Resources DELAWARE RIVER BASIN... exploratory drilling. The Commission encourages consultation with any project sponsor who is considering... project and prior to initiation of exploratory drilling. (a) Any person, firm corporation or other entity...

Geologic report on the Sand Wash Drilling Project, Moffat and Routt Counties, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, T.E.; Wayland, T.E.

1981-09-01

The Sand Wash Basin Drilling Project comprises twenty-seven (27) drill holes located in Moffat and Routt Counties, northwest Colorado, having an aggregate depth of 26,107.5 feet (7957.6 m). The holes penetrate the Browns Park Formation of Miocene age, which is a tuffaceous continental sandstone deposited in fluvial, eolian, and lacustrine environments. Partly based on project drilling results, uranium potential resource estimates for this formation in the $50/lb U/sub 3/O/sub 8/ forward-cost category have been increased by 34,476 tons U/sub 3/O/sub 8/ (35,036 metric tons). Three areas between Maybell and Craig, Colorado, considered favorable for uranium occurrences were verified as favorablemore » by project drilling, and a fourth favorable area northwest of Maybell has been expanded. In addition, project drilling results indicate two new favorable areas, one north and northwest and one south of Steamboat Springs, Colorado. Anomalous radioactivity was detected in drill holes in all six study areas of the project. The most important factor in concentrating significant amounts of uranium in the target formation appears to be the availability of gaseous or liquid hydrocarbons and/or hydrogen sulfide gas as reductants. Where subjacent formations supply these reductants to the Browns Park Formation, project drilling encountered 0.05 percent to 0.01 percent uranium concentrations. Potential, though unproven, sources of these reductants are believed to underlie parts of all six project study areas.« less

Structural deformation at the Flynn Creek impact crater, Tennessee - A preliminary report on deep drilling

NASA Technical Reports Server (NTRS)

Roddy, D. J.

1979-01-01

The geologic and core drilling studies described in the present paper show that the Flynn Creek crater has such distinctive morphological features as a broad flat hummocky floor; large central peak; locally terraced crater walls; uplifted, as well as flat-lying rim segments; and a surrounding ejecta blanket. The major structural features include a shallow depth of total brecciation and excavation as compared with apparent crater diameter; a thin breccia lens underlain by a thin zone of disrupted strata; concentric ring fault zones in inner rim, beneath crater wall, and outer crater floor regions; a large central uplift underlain by a narrow dipping zone of deeply disrupted strata; faulted, folded, brecciated, and fractured rim strata; and uplifted rim strata, which dip away from the crater, and flat-lying rim strata, which terminate as inward dipping rocks.

Support of EarthScope GPS Campaigns at the UNAVCO Facility

NASA Astrophysics Data System (ADS)

Boyce, E.; Blume, F.; Normandeau, J.

2008-12-01

In order to support portable GPS deployments funded by the NSF's EarthScope Science panel, PBO has purchased 100 campaign GPS systems. Based Topcon GB-1000 equipment, the systems have been designed for stand-alone temporary or semi-permanent deployment that will be used for densifying areas not sufficiently covered by continuous GPS, and responding to volcanic and tectonic crises. UNAVCO provides support for all aspects of these projects, including proposal and budget development, project planning, equipment design, field support, and data archiving. Ten of the 100 systems have been equipped with real-time kinematic (RTK) capability requiring additional radio and data logging equipment. RTK systems can be used to rapidly map fault traces and profile fault escarpments and collect precise position information for GIS based geologic mapping. Each portable self-contained campaign systems include 18 Ah batteries, a regulated 32 watt solar charging system, and a low-power dual frequency GPS receiver and antenna in a waterproof case with security enhancements. The receivers have redundant memory sufficient for storing over a year's worth of data as well as IP and serial communications capabilities for longer-term deployments. Monumentation options are determined on a project-by-project basis, with options including Tech2000 masts, low-profile spike mounts, and traditional tripods and optical tribrachs. Drilled-braced monuments or masts can be installed for "semi- permanent" style occupations. The systems have been used to support several projects to date, including the University of Washington's 30-unit deployment to monitor the Episodic Tremor and Slip event in November, 2005 and the ongoing Rio Grande Rift experiment, run by the Universities of Colorado, Utah State, and New Mexico, which has seen the construction of 25 permanent monuments in 2006 and 2007 and a 26-site campaign reoccupation in 2008.

Support of EarthScope GPS Campaigns at the UNAVCO Facility

NASA Astrophysics Data System (ADS)

Boyce, E.; Blume, F.; Normandeau, J.

2007-12-01

In order to support portable GPS deployments funded by the NSF's EarthScope Science panel, PBO has purchased 100 campaign GPS systems. Based Topcon GB-1000 equipment, the systems have been designed for stand-alone temporary or semi-permanent deployment that will be used for densifying areas not sufficiently covered by continuous GPS, and responding to volcanic and tectonic crises. UNAVCO provides support for all aspects of these projects, including proposal and budget development, project planning, equipment design, field support, and data archiving. Ten of the 100 systems will be purchased with real-time kinematic (RTK) capability requiring additional radio and data logging equipment. RTK systems can be used to rapidly map fault traces and profile fault escarpments and collect precise position information for GIS based geologic mapping. Each portable self-contained campaign systems include 18 Ah batteries, a regulated 32 watt solar charging system, and a low-power dual frequency GPS receiver and antenna in a waterproof case with security enhancements. The receivers have redundant memory sufficient for storing over a year's worth of data as well as IP and serial communications capabilities for longer-term deployments. Monumentation options are determined on a project-by-project basis, with options including Tech2000 masts, low-profile spike mounts, and traditional tripods and optical tribrachs. Drilled-braced monuments or masts can be installed for "semi-permanent" style occupations. The systems have been used to support several projects to date, including the University of Washington's 30- unit deployment to monitor the Episodic Tremor and Slip event in November, 2005 and the ongoing Rio Grande Rift experiment, run by the Universities of Colorado, Utah State, and New Mexico, which has seen the construction of 25 permanent monuments in 2006 and 2007.

Drilling informatics: data-driven challenges of scientific drilling

NASA Astrophysics Data System (ADS)

Yamada, Yasuhiro; Kyaw, Moe; Saito, Sanny

2017-04-01

The primary aim of scientific drilling is to precisely understand the dynamic nature of the Earth. This is the reason why we investigate the subsurface materials (rock and fluid including microbial community) existing under particular environmental conditions. This requires sample collection and analytical data production from the samples, and in-situ data measurement at boreholes. Current available data comes from cores, cuttings, mud logging, geophysical logging, and exploration geophysics, but these datasets are difficult to be integrated because of their different kinds and scales. Now we are producing more useful datasets to fill the gap between the exiting data and extracting more information from such datasets and finally integrating the information. In particular, drilling parameters are very useful datasets as geomechanical properties. We believe such approach, 'drilling informatics', would be the most appropriate to obtain the comprehensive and dynamic picture of our scientific target, such as the seismogenic fault zone and the Moho discontinuity surface. This presentation introduces our initiative and current achievements of drilling informatics.

Some thorium prospects, Lemhi Pass area, Beaverhead County, Montana

USGS Publications Warehouse

Armstrong, Frank C.

1955-01-01

The Last Chance group> Brown Bear and Shady Tree claims in Beaverhead County, Mont., were explored for thorium under a Defense Minerals Exploration Administration Contract in 1951 and 1952. The project was undertaken to explore northwest-trending moderately to steep dipping, thorite-bearing quartz-barite-hematite veins. The veins are wall-rock replacements and fissure fillings in faults and shears that cut rocks of the Precambrian Belt series. Recurrent movement along the faults has intense fractured the veins. Quartz iron-oxide minerals, and thorite have been deposited in these fractures. The iron oxides and thorite are intimately associated and were among the last minerals deposited. Because no rare earth or uranium minerals have been found in the veins, it is thought that the small amounts of these elements reported in the analyses must substitute for thorium in the thorite. Under the D. M. E. A. contract the Last Chance vein was traced on surface for a distance of about 1,300 feet; the thickness ranges from about 35 feet to a few inches. Two diamond drill holes cut the vein 240 and 290 feet below the outcrop.

Satellite tree subsea completions permit marginal reserves production offshore East Kalimantan, Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunnell, R.L.; Hawkins, J.G.

1983-05-01

The hydrocarbon-bearing sands in the fields offshore East Kalimantan were deposited in a deltaic environment and are complicated by faulting. This faulting results in small accumulations which cannot be economically exploited by conventional means. Three of these accumulations had been discovered in the Attaka Field in water depths of 160-190 feet. Even though the weather conditions are mild, conventional platforms were ruled out on economic grounds. An alternate method employing subsea completions was found to be economically viable. This subsea system is characterized by its ''off-the-shelf'' configuration and simplicity. To reduce the possibility of required well workovers, the wells aremore » single string, gravel packed completions. This project, then, is an example of a subsea completion system being chosen for marginal reserve development based on economic grounds. Additionally, these are the first subsea completions in Indonesia and yielded much information for use in designing, scheduling, and costing similar installations. The wells were all previously drilled and suspended exploratory wells, and the completion operations were performed from a floating vessel.« less

Paleoseismological surveys on the Hinagu fault zone in Kumamoto, central Kyushu, Japan

NASA Astrophysics Data System (ADS)

Azuma, T.

2017-12-01

The Hinagu fault zone is located on the south of the Futagawa fault zone, which was a main part of the source fault of the 2016 Kumamoto earthquake of Mj 7.3. Northernmost part of the Hinagu fault zone was also acted in 2016 event and surface faults with right-lateral displacement upto ca. 50 cm were appeared. Seismicity along the central part of the Hinagu fault was increased just after the 2016 Kumamoto Earthquake. It seems that the Hinagu fault zone would produce the next large earthquake in the near future, although it has not occurred yet. The Headquarters of the Earthquake Research Promotions (HERP) conducted active fault surveys on the Hinagu fault zone to recognize the probability of the occurrence of the next faulting event. The Hinagu fault zone is composed with 3 fault segments, Takano-Shirahata, Hinagu, and Yatsushiro Bay. Yatsushiro Bay segment is offshore fault. In FY2016, we conducted paleoseismological trenching surveys at 2 sites (Yamaide, Minamibeta) and offshore drilling. Those result showed evidences that the recurrence intervals of the Hinagu fault zone was rather short and the last faulting event occurred around 1500-2000 yrsBP. In FY2017, we are planning another trenching survey on the southern part of the central segment, where Yatsushiro city located close to the fault.

HIGH UINTAS PRIMITIVE AREA, UTAH.

USGS Publications Warehouse

Crittenden, Max D.; Sheridan, Michael J.

1984-01-01

Mineral surveys in the High Uintas Primitive Area, Utah and the additions subsequently proposed concluded that the area has little promise for mineral resources. Of the areas around the fringes, a strip along the north flank fault can be classed as having probable energy-resource potential for oil and gas. The oil and gas potential could be tested by additional seismic studies followed by drilling. Much of the necessary information probably could be obtained without drilling within the primitive area itself.

Tectonic evolution of the outer Izu-Bonin-Mariana fore arc system: initial results from IODP Expedition 352

NASA Astrophysics Data System (ADS)

Kurz, W.; Ferre, E. C.; Robertson, A. H. F.; Avery, A. J.; Kutterolf, S.

2015-12-01

During International Ocean Discovery Program (IODP) Expedition 352, a section through the volcanic stratigraphy of the outer fore arc of the Izu-Bonin-Mariana (IBM) system was drilled to trace magmatism, tectonics, and crustal accretion associated with subduction initiation. Structures within drill cores, borehole and site survey seismic data indicate that tectonic deformation in the outer IBM fore arc is mainly post-magmatic. Extension generated asymmetric sediment basins such as half-grabens at sites 352-U1439 and 352-U1442 on the upper trench slope. Along their eastern margins the basins are bounded by west-dipping normal faults. Deformation was localized along multiple sets of faults, accompanied by syn-tectonic pelagic and volcaniclastic sedimentation. The lowermost sedimentary units were tilted eastward by ~20°. Tilted beds were covered by sub-horizontal beds. Biostratigraphic constraints reveal a minimum age of the oldest sediments at ~ 35 Ma; timing of the sedimentary unconformities is between ~ 27 and 32 Ma. At sites 352-U1440 and 352-U1441 on the outer fore arc strike-slip faults are bounding sediment basins. Sediments were not significantly affected by tectonic tilting. Biostratigraphy gives a minimum age of the basement-cover contact between ~29.5 and 32 Ma. The post-magmatic structures reveal a multiphase tectonic evolution of the outer IBM fore arc. At sites 352-U1439 and 352-U1442, shear with dominant reverse to oblique reverse displacement was localized along subhorizontal fault zones, steep slickensides and shear fractures. These were either re-activated as or cut by normal-faults and strike-slip faults. Extension was also accommodated by steep to subvertical mineralized veins and extensional fractures. Faults at sites 352-U1440 and 352-U1441 show mainly strike-slip kinematics. Sediments overlying the igneous basement(maximum Late Eocene to Recent age), document ash and aeolian input, together with mass wasting of the fault-bounded sediment ponds.

Creation of an Enhanced Geothermal System through Hydraulic and Thermal Stimulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Peter Eugene

2013-04-15

This report describes a 10-year DOE-funded project to design, characterize and create an Engineered Geothermal System (EGS) through a combination of hydraulic, thermal and chemical stimulation techniques. Volume 1 describes a four-year Phase 1 campaign, which focused on the east compartment of the Coso geothermal field. It includes a description of the geomechanical, geophysical, hydraulic, and geochemical studies that were conducted to characterize the reservoir in anticipation of the hydraulic stimulation experiment. Phase 1 ended prematurely when the drill bit intersected a very permeable fault zone during the redrilling of target stimulation well 34-9RD2. A hydraulic stimulation was inadvertently achieved,more » however, since the flow of drill mud from the well into the formation created an earthquake swarm near the wellbore that was recorded, located, analyzed and interpreted by project seismologists. Upon completion of Phase 1, the project shifted focus to a new target well, which was located within the southwest compartment of the Coso geothermal field. Volume 2 describes the Phase 2 studies on the geomechanical, geophysical, hydraulic, and geochemical aspects of the reservoir in and around target-stimulation well 46A-19RD, which is the deepest and hottest well ever drilled at Coso. Its total measured depth exceeding 12,000 ft. It spite of its great depth, this well is largely impermeable below a depth of about 9,000 ft, thus providing an excellent target for stimulation. In order to prepare 46A-19RD for stimulation, however, it was necessary to pull the slotted liner. This proved to be unachievable under the budget allocated by the Coso Operating Company partners, and this aspect of the project was abandoned, ending the program at Coso. The program then shifted to the EGS project at Desert Peak, which had a goal similar to the one at Coso of creating an EGS on the periphery of an existing geothermal reservoir. Volume 3 describes the activities that the Coso team contributed to the Desert Peak project, focusing largely on a geomechanical investigation of the Desert Peak reservoir, tracer testing between injectors 21-2 and 22-22 and the field's main producers, and the chemical stimulation of target well 27-15.« less

Creation of an Enhanced Geothermal System through Hydraulic and Thermal Stimulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Peter Eugene

This report describes a 10-year DOE-funded project to design, characterize and create an Engineered Geothermal System (EGS) through a combination of hydraulic, thermal and chemical stimulation techniques. Volume 1 describes a four-year Phase 1 campaign, which focused on the east compartment of the Coso geothermal field. It includes a description of the geomechanical, geophysical, hydraulic, and geochemical studies that were conducted to characterize the reservoir in anticipation of the hydraulic stimulation experiment. Phase 1 ended prematurely when the drill bit intersected a very permeable fault zone during the redrilling of target stimulation well 34-9RD2. A hydraulic stimulation was inadvertently achieved,more » however, since the flow of drill mud from the well into the formation created an earthquake swarm near the wellbore that was recorded, located, analyzed and interpreted by project seismologists. Upon completion of Phase 1, the project shifted focus to a new target well, which was located within the southwest compartment of the Coso geothermal field. Volume 2 describes the Phase 2 studies on the geomechanical, geophysical, hydraulic, and geochemical aspects of the reservoir in and around target-stimulation well 46A-19RD, which is the deepest and hottest well ever drilled at Coso. Its total measured depth exceeding 12,000 ft. It spite of its great depth, this well is largely impermeable below a depth of about 9,000 ft, thus providing an excellent target for stimulation. In order to prepare 46A-19RD for stimulation, however, it was necessary to pull the slotted liner. This proved to be unachievable under the budget allocated by the Coso Operating Company partners, and this aspect of the project was abandoned, ending the program at Coso. The program then shifted to the EGS project at Desert Peak, which had a goal similar to the one at Coso of creating an EGS on the periphery of an existing geothermal reservoir. Volume 3 describes the activities that the Coso team contributed to the Desert Peak project, focusing largely on a geomechanical investigation of the Desert Peak reservoir, tracer testing between injectors 21-2 and 22-22 and the field's main producers, and the chemical stimulation of target well 27-15.« less

Does velocity-strengthening to velocity-weakening transition really determine the updip limit of the seismogenic zone in subduction megathrusts?

NASA Astrophysics Data System (ADS)

Shimamoto, T.

2009-12-01

Understanding the mechanisms of thrust-type earthquakes in subduction zones is the primary target of seismogenic-zone drilling project in Nankai Trough. Drilling into the upper part of the seismogenic zone is attempted, so that understanding the processes controlling the updip limit of the seismogenic zone is becoming a more specific target. A commonly accepted notion is that the onset of seismic behavior is due to a change in velocity strengthening to velocity weakening property of fault zone (see Saffer & Marone, 2003, EPSL ). Smectite-illite transformation had been a fashionable hypothesis for such a transition because the transformation is likely to occur near the updip limit of the seismogenic zone. However, Saffer & Marone recognized velocity-strengthening behavior of illite gouge questioning the smectite-illite transformation as the primary cause for the updip limit of seismic zone. They explored other possibilities that might cause a change in the velocity dependency of friction. I want to address the problem from a different angle. Progress in high-velocity friction in the last 15 years has demonstrated that nearly all faults exhibit dramatic weakening at high slip rates and large displacements. The weakening is indeed greater than the changes in friction at slow slip rates by more than one order of magnitude, and the slip- and velocity-weakening of faults at high velocities is likely to control the dynamic fault motion during large earthquakes. Thus by combining abundant work on rate-and-state dependent friction at slow slip rates and recent high-velocity friction studies, a possibility emerges in that the rate-and-state friction at slow slip rates controls the earthquake nucleation, whereas intermediate to high-velocity friction dictates the growth processes into a large earthquake. Taiwan Chi-Chi earthquake in 1999 is very interesting in this regard because Tanikawa & Shimamoto (2008, JGR ) recognized velocity-strengthening properties for gouge from the northern part of the Chelungpu fault (velocity weakening for gouge from the south). The northern part of the fault should be aseismic according to a traditional view for earthquakes in velocity-weakening regime, whereas the northern part displaced much more at higher slip rates with lower frequencies than in southern part. Permeability of fault gouge is lower in the north than in the south by one to two orders of magnitude, so that high-velocity weakening is more pronounced in the north due to more effective thermal pressurization than in the south. Thus Tanikawa & Shimamoto proposed a scenario that the Chi-Chi earthquake started from the southern part of Chelungpu fault with velocity-weakening property and that the earthquake rupture grew more in the north due to high-velocity weakening. Noda & Lapusta (2009, JPGU meeting ) demonstrated by dynamic modeling that such a scenario is indeed possible. I propose that such a scenario is applicable to shallow subduction zone where earthquake rupture comes from deeper parts. This change in view will change the scope of laboratory work, modeling, and even ways of looking at faults in accretionary prism such as Shimanto belt. Those problems will be elaborated in my presentation.

Drilling into the deep interior of the Nankai accretionary prism: Preliminary results of IODP NanTroSEIZE Expedition 348

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Hirose, T.; Saffer, D. M.; Toczko, S.; Maeda, L.

2014-12-01

International Ocean Discovery Program (IODP) Expedition 348, the latest advance of the NanTroSEIZE project, started on 13 September 2013 and was completed on 29 January 2014. During Expedition 348, the drilling vessel Chikyu advanced the ultra-deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula, from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf, the world record for the deepest scientific ocean drilling, and cased it for future deepening. The drilling operation successfully obtained data on formation physical properties from logging while drilling (LWD) tools, as well as from lithological analyses of cuttings and core from the interior of the active accretionary prism at the Nankai Trough. IODP Site C0002 is the currently only borehole to access the deep interior of an active convergent margin. Preliminary scientific results of Expedition 348 are as follows: (1) Fine-grained turbiditic mudstones with coarser silty and sandy interbeds, exhibiting steep dips (between ~60 and 90 degrees) are predominant in the prism down to ~3000 mbsf. The biostratigraphic age of the sediments in the lowermost part of the hole is thought to be 9-11 Ma, with an assumed age of accretion of 3-5 Ma. (2) Slickenlined surfaces, deformation bands and mineral veins are present throughout the drilled interval, while well-developed scaly clay fabrics are increasingly observed below ~2200 mbsf. A substantial fault zone with well-developed foliation was successfully cored from the deep interior of the prism at ~2205 mbsf. (3) Porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf. However, physical properties including grain density, electrical conductivity and P-wave velocity suggest fairly homogeneous properties in the interior of the prism between ~2000 and 3000 mbsf. (4) Mud gas analysis during the riser drilling indicates that a source of methane gas shifts from microbial origin to thermogenic at around 2325 mbsf. (5) The maximum horizontal principal stress at ~2200 mbsf is in the NE-SW direction. The inner wedge at ~ 2000 mbsf is currently in a strike-slip stress regime.

Drill drive mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dressel, M.O.

1979-10-30

A drill drive mechanism is especially adapted to provide both rotational drive and axial feed for a drill of substantial diameter such as may be used for drilling holes for roof bolts in mine shafts. The drill shaft is made with a helical pattern of scroll-like projections on its surface for removal of cuttings. The drill drive mechanism includes a plurality of sprockets carrying two chains of drive links which are arranged to interlock around the drill shaft with each drive link having depressions which mate with the scroll-like projections. As the chain links move upwardly or downwardly the surfacesmore » of the depressions in the links mate with the scroll projections to move the shaft axially. Tangs on the drive links mate with notch surfaces between scroll projections to provide a means for rotating the shaft. Projections on the drive links mate together at the center to hold the drive links tightly around the drill shaft. The entire chain drive mechanism is rotated around the drill shaft axis by means of a hydraulic motor and gear drive to cause rotation of the drill shaft. This gear drive also connects with a differential gearset which is interconnected with a second gear. A second motor is connected to the spider shaft of the different gearset to produce differential movement (speeds) at the output gears of the differential gearset. This differential in speed is utilized to drive said second gear at a speed different from the speed of said gear drive, this speed differential being utilized to drive said sprockets for axial movement of said drill shaft. 11 claims.« less

Drill drive mechanism

DOEpatents

Dressel, Michael O.

1979-01-01

A drill drive mechanism is especially adapted to provide both rotational drive and axial feed for a drill of substantial diameter such as may be used for drilling holes for roof bolts in mine shafts. The drill shaft is made with a helical pattern of scroll-like projections on its surface for removal of cuttings. The drill drive mechanism includes a plurality of sprockets carrying two chains of drive links which are arranged to interlock around the drill shaft with each drive link having depressions which mate with the scroll-like projections. As the chain links move upwardly or downwardly the surfaces of the depressions in the links mate with the scroll projections to move the shaft axially. Tangs on the drive links mate with notch surfaces between scroll projections to provide a means for rotating the shaft. Projections on the drive links mate together at the center to hold the drive links tightly around the drill shaft. The entire chain drive mechanism is rotated around the drill shaft axis by means of a hydraulic motor and gear drive to cause rotation of the drill shaft. This gear drive also connects with a differential gearset which is interconnected with a second gear. A second motor is connected to the spider shaft of the differential gearset to produce differential movement (speeds) at the output gears of the differential gearset. This differential in speed is utilized to drive said second gear at a speed different from the speed of said gear drive, this speed differential being utilized to drive said sprockets for axial movement of said drill shaft.

Crustal Structure and Deformation of the Yakutat Microplate: New Insights From STEEP Marine Seismic Reflection Data

NASA Astrophysics Data System (ADS)

Lowe, L. A.; Gulick, S. P.; Christeson, G.; van Avendonk, H.; Reece, R.; Elmore, R.; Pavlis, T.

2008-12-01

In fall 2008, we will conduct an active source marine seismic experiment of the offshore Yakutat microplate in the northern Gulf of Alaska. The survey will be conducted aboard the academic research vessel, R/V Marcus Langseth, collecting deep-penetrating multi-channel seismic reflection survey using an 8-km, 640 channel hydrophone streamer and a 6600 cu. in., 36 airgun array. The survey is the concluding data acquisition phase for the ST. Elias Erosion and tectonics Project (STEEP), a multi-institution NSF-Continental Dynamics project investigating the interplay of climate and tectonics in the Chugach-St. Elias Mountains in southern Alaska. The experiment will also provide important site survey information for possible future Integrated Ocean Drilling Program investigations. Two profiles coincident with wide-angle refraction data (see Christeson, et al., this session) will image structural changes across the Dangerous River Zone from east to west and the Transition Fault from south to north. We will also image the western portion of the Transition Fault to determine the nature of faulting along this boundary including whether or not the Pacific Plate is underthrusting beneath the Yakutat microplate as part of this collision. Our westernmost profile will image the Kayak Island Zone, typically described as the northern extension of the Aleutian megathrust but which may be a forming suture acting as a deformation backstop for the converging Yakutat and North American plates. Profiles across the Pamplona Zone, the current Yakutat-North America deformation front, will further constrain relative timing of structural development and the depth of deformation on the broad folds and thrust faults that comprise the area. This new dataset will allow further insight into regional tectonics of the St. Elias region as well as provide more detail regarding the development of the south Alaskan margin during major Plio-Pleistocene glacial- interglacial periods.

Make-up wells drilling cost in financial model for a geothermal project

NASA Astrophysics Data System (ADS)

Oktaviani Purwaningsih, Fitri; Husnie, Ruly; Afuar, Waldy; Abdurrahman, Gugun

2017-12-01

After commissioning of a power plant, geothermal reservoir will encounter pressure decline, which will affect wells productivity. Therefore, further drilling is carried out to enhance steam production. Make-up wells are production wells drilled inside an already confirmed reservoir to maintain steam production in a certain level. Based on Sanyal (2004), geothermal power cost consists of three components, those are capital cost, O&M cost and make-up drilling cost. The make-up drilling cost component is a major part of power cost which will give big influence in a whole economical value of the project. The objective of this paper it to analyse the make-up wells drilling cost component in financial model of a geothermal power project. The research will calculate make-up wells requirements, drilling costs as a function of time and how they influence the financial model and affect the power cost. The best scenario in determining make-up wells strategy in relation with the project financial model would be the result of this research.

Drilling Automation Tests At A Lunar/Mars Analog Site

NASA Technical Reports Server (NTRS)

Glass, B.; Cannon, H.; Hanagud, S.; Lee, P.; Paulsen, G.

2006-01-01

Future in-situ lunar/martian resource utilization and characterization, as well as the scientific search for life on Mars, will require access to the subsurface and hence drilling. Drilling on Earth is hard - an art form more than an engineering discipline. The limited mass, energy and manpower in planetary drilling situations makes application of terrestrial drilling techniques problematic. The Drilling Automation for Mars Exploration (DAME) project is developing drilling automation and robotics for projected use in missions to the Moon and Mars in the 2011-15 period. This has been tested recently, drilling in permafrost at a lunar/martian analog site (Haughton Crater, Devon Island, Canada).

Seismic calibration shots conducted in 2009 in the Imperial Valley, southern California, for the Salton Seismic Imaging Project (SSIP)

USGS Publications Warehouse

Murphy, Janice; Goldman, Mark; Fuis, Gary; Rymer, Michael; Sickler, Robert; Miller, Summer; Butcher, Lesley; Ricketts, Jason; Criley, Coyn; Stock, Joann; Hole, John; Chavez, Greg

2011-01-01

Rupture of the southern section of the San Andreas Fault, from the Coachella Valley to the Mojave Desert, is believed to be the greatest natural hazard facing California in the near future. With an estimated magnitude between 7.2 and 8.1, such an event would result in violent shaking, loss of life, and disruption of lifelines (freeways, aqueducts, power, petroleum, and communication lines) that would bring much of southern California to a standstill. As part of the Nation's efforts to prevent a catastrophe of this magnitude, a number of projects are underway to increase our knowledge of Earth processes in the area and to mitigate the effects of such an event. One such project is the Salton Seismic Imaging Project (SSIP), which is a collaborative venture between the United States Geological Survey (USGS), California Institute of Technology (Caltech), and Virginia Polytechnic Institute and State University (Virginia Tech). This project will generate and record seismic waves that travel through the crust and upper mantle of the Salton Trough. With these data, we will construct seismic images of the subsurface, both reflection and tomographic images. These images will contribute to the earthquake-hazard assessment in southern California by helping to constrain fault locations, sedimentary basin thickness and geometry, and sedimentary seismic velocity distributions. Data acquisition is currently scheduled for winter and spring of 2011. The design and goals of SSIP resemble those of the Los Angeles Region Seismic Experiment (LARSE) of the 1990's. LARSE focused on examining the San Andreas Fault system and associated thrust-fault systems of the Transverse Ranges. LARSE was successful in constraining the geometry of the San Andreas Fault at depth and in relating this geometry to mid-crustal, flower-structure-like decollements in the Transverse Ranges that splay upward into the network of hazardous thrust faults that caused the 1971 M 6.7 San Fernando and 1987 M 5.9 Whittier Narrows earthquakes. The project also succeeded in determining the depths and seismic-velocity distributions of several sedimentary basins, including the Los Angeles Basin, San Fernando Valley, and Antelope Valley. These results advanced our ability to understand and assess earthquake hazards in the Los Angeles region. In order to facilitate permitting and planning for the data collection phase of SSIP, in June of 2009 we set off calibration shots and recorded the seismic data with a variety of instruments at varying distances. We also exposed sections of buried clay drainage pipe near the shot points to determine the effect of seismic energy on the pipes. Clay drainage pipes are used by the irrigation districts in both the Coachella and Imperial Valleys to prevent ponding and remove salts and irrigation water. This report chronicles the calibration project. We present new near-source velocity data that are used to test the regression curves that were determined for the LARSE project. These curves are used to create setback tables to determine explosive charge size and for placement of shot points. We also found that our shots did not damage the irrigation pipes and that the ODEX drilling system did well in the clay rich soils of the Imperial Valley.

Analysis and interpretation of stress indicators in deviated wells of the Coso Geothermal Field

USGS Publications Warehouse

Schoenball, Martin; Glen, Jonathan M. G.; Davatzes, Nicholas C.

2016-01-01

Characterizing the tectonic stress field is an integral part of the development of hydrothermal systems and especially for enhanced geothermal systems (EGS). With a well characterized stress field the propensity of fault slip on faults with known location and orientation can be identified. Faults that are critically oriented for faulting with respect to the stress field are known to provide natural fluid pathways. A high slip tendency makes a fault a likely candidate for reactivation during the creation of an EGS. Similarly, the stress state provides insight for the potential of larger, damaging earthquakes should extensive portions of well-oriented, larger faults be reactivated.The analysis of stress indicators such as drilling-induced fractures and borehole breakouts is the main tool to infer information on the stress state of a geothermal reservoir. The standard procedure is applicable to sub-vertical wellbore sections and highly deviated sections have to be discarded. However, in order to save costs and reduce the environmental impact most recent wells are directionally drilled with deviations that require appropriate consideration of the deviated trajectory. Here we present an analysis scheme applicable to arbitrary well trajectories or a combination of wells to infer the stress state. Through the sampling of the stress tensor along several directions additional information on the stress regime and even relative stress magnitudes can be obtained. We apply this method on image logs from the pair of wells 58-10 and 58A-10 that were drilled from the same well pad. Both wells have image logs of about 2km of their trajectories that are separated by less than 300m. For both wells we obtain a mean orientation of SHmax of N23° with large standard deviations of locations of stress indicators of 24° and 26°, respectively. While the local stress direction is highly variable along both wells with dominant wavelengths from around 50 to 500m, the mean directions are very consistent and also agree with previous stress estimates in the eastern part of the Coso Geothermal Field. In order to obtain a reliable estimation of the stress orientation in this setting, it is necessary to sample the stress field on an interval long to capture several of the dominant wavelengths.

Interpretation of a leak-off test conducted near the bottom of the Kumano Forearc Basin strata at IODP Site C0002 in the Nankai accretionary complex, SW Japan

NASA Astrophysics Data System (ADS)

Song, I.; Huepers, A.; Olcott, K. A.; Saffer, D. M.; Dugan, B.; Strasser, M.

2013-12-01

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a long-term, multi-stage scientific drilling project launched for investigating fault mechanics and seismogenesis along subduction megathrusts. One main key to the mechanics of the plate boundary is understanding the absolute mechanical strength and the in situ stress along the megathrust. As part of efforts to access the Nankai Trough seismogenic zone, the NanTroSEIZE Integrated Ocean Drilling Program (IODP) project began riser-based drilling operations at Site C0002 (Hole C0002F) in 2010 during IODP Expedition 326, with the objective of reaching the plate interface at ~6800 meters below the seafloor (mbsf). The geology in this area is composed of the Kumano Forearc Basin sedimentary strata to ~940 mbsf, underlain by the inner accretionary wedge. IODP Expedition 326 drilled Hole C0002F to 872.5 mbsf, near the bottom of the Kumano Basin, and set a 20-inch casing string to 860.2 mbsf. During IODP Expedition 338 in 2012, the hole was extended to 2005.5 mbsf. At the beginning of the operation, a leak-off test (LOT) was conducted in the interval of 872.5-875.5 mbsf, to define the maximum mud weight for the next stage of logging-while-drilling (LWD). Drilling-out-cement (DOC) at the bottom of the hole prior to the LOT provided a 3-m long, 17-inch diameter open borehole for the LOT. For the LOT, this open hole interval was pressurized with the outer annulus closed by the blow out preventer (BOP) using drilling mud of density of 1100 kg/m3, and mud pressure was measured at the cement pumps. The bottom-hole pressure was calculated by the recorded pressure plus the static pressure of the mud column. The first cycle of pressurization was conducted with injection of drilling mud at 31.8 l/min. However, the leak-off pressure (LOP) was not clearly defined because a large volume of mud was lost. Therefore a second cycle was conducted with a higher drilling mud injection rate (47.7 l /min). The rapid increase in pressure with a lower volume of mud injected during the second cycle suggests that a good mud cake was formed around the borehole wall, possibly due to mud flowing into the formation during the first cycle. In the second cycle, we identify a LOP of ~32.0 MPa from the pressure-volume record, which we interpret as the least principal stress. The total vertical stress given by the integration of bulk density with respect to depth is 35.7 MPa, indicating that the LOP reflects the least horizontal stress. This result can be a solid basis to constrain the in situ state of stress from indirect stress indicators such as wellbore failures at other depths.

McGee Mountain Shallow (2m) Temperature Survey, Humboldt County, Nevada 2009

DOE Data Explorer

Richard Zehner

2009-01-01

This shapefile contains location and attribute data for a shallow (2 meter) temperature survey conducted by Geothermal Technical Partners, Inc. during late 2008 and early 2009. Temperatures at 2m depth were measured at 192 separate points as outlined by Coolbaugh et al., 2007. The purpose of the survey was to try and detect a shallow thermal anomaly associated with the McGee Mountain geothermal area as discovered by Phillips Petroleum and Earth Power Resources in the late 1970’s. Drilling identified ~120oC temperatures at ~100m depth. This 2-meter survey delineated what was interpreted as a steam-heated fault zone centered along a range front fault in the vicinity of the drilled holes and fumaroles. Coolbaugh, M.F., Sladek, C., Faulds, J.E., Zehner, R.E., and Oppliger, G.L., 2007, Use of rapid temperature measurements at a 2-meter depth to augment deeper temperature gradient drilling: Proceedings, 32nd Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA, Jan. 22-24, 2007, p. 109-116. Zehner, R., Tullar, K., and Rutledge, E., 2012, Effectiveness of 2-Meter and geoprobe shallow temperature surveys in early stage geothermal exploration: Geothermal Resources Council Transactions, v. 36, in press.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stone, D.M.; Huffmyer, W.A.; Greener, J.M.

This paper describes the geoscience and engineering aspects of the Opon Gas Field located in the Middle Magdalena Basin, Colombia. The remoteness and extreme downhole conditions make the drilling, completion, testing and geoscience interpretation of the two most recent Opon wells technically very challenging. Multiple faults, steep dips, rugged topography, a sensitive jungle environment and variable surface velocities complicate field definition. A full assessment of the commercial potential of the reservoir requires additional development drilling. Now in the early development stages, the Opon Gas Field has first production scheduled for late 1996.

Geologic applications of ERTS images on the Colorado Plateau, Arizona

NASA Technical Reports Server (NTRS)

Goetz, A. F. H.; Billingsley, F. C.; Elston, D. P.; Lucchitta, I.; Shoemaker, E. M.

1974-01-01

Three areas in central and northern Arizona centered on the (1) Verde Valley, (2) Coconino Plateau, and (3) Shivwits Plateau were studied using ERTS photography. Useful applications results include: (1) upgrading of the existing state geologic map of the Verde Valley region; (2) detection of long NW trending lineaments in the basalt cap SE of Flagstaff which may be favorable locations for drilling for new water supplies; (3) tracing of the Bright Angel and Butte faults to twice their previously known length and correlating the extensions with modern seismic events, showing these faults to be present-day earthquake hazards; (4) discovering and successfully drilling perched sandstone aquifers in the Kaibab Limestone on the Coconino Plateau; and (5) determining the relationship between the Shivwits lavas and the formation of the lower Grand Canyon and showing that the lavas should be an excellent aquifer, as yet untapped.

Results of a test well in the Nanafalia Formation near Melvin, Choctaw County, Alabama

USGS Publications Warehouse

Davis, M.E.; Sparkes, A.K.; Peacock, B.S.

1983-01-01

Test drilling at Melvin, Choctaw County, Alabama, discloses that the Nanafalia Formation (Paleocene) contains freshwater in sand at a distance of 25 miles downdip from the outcrop area. A nearby fault on the north side of Gilberttown-Pickens fault zone does not appear to affect either the head or the water quality in sand of the Nanafalia. This presently undeveloped aquifer could be a source of water supply in this area. (USGS)

Relationship Between Faults Oriented Parallel and Oblique to Bedding in Neogene Massive Siliceous Mudstones at The Horonobe Underground Research Laboratory, Japan

NASA Astrophysics Data System (ADS)

Hayano, Akira; Ishii, Eiichi

2016-10-01

This study investigates the mechanical relationship between bedding-parallel and bedding-oblique faults in a Neogene massive siliceous mudstone at the site of the Horonobe Underground Research Laboratory (URL) in Hokkaido, Japan, on the basis of observations of drill-core recovered from pilot boreholes and fracture mapping on shaft and gallery walls. Four bedding-parallel faults with visible fault gouge, named respectively the MM Fault, the Last MM Fault, the S1 Fault, and the S2 Fault (stratigraphically, from the highest to the lowest), were observed in two pilot boreholes (PB-V01 and SAB-1). The distribution of the bedding-parallel faults at 350 m depth in the Horonobe URL indicates that these faults are spread over at least several tens of meters in parallel along a bedding plane. The observation that the bedding-oblique fault displaces the Last MM fault is consistent with the previous interpretation that the bedding- oblique faults formed after the bedding-parallel faults. In addition, the bedding-parallel faults terminate near the MM and S1 faults, indicating that the bedding-parallel faults with visible fault gouge act to terminate the propagation of younger bedding-oblique faults. In particular, the MM and S1 faults, which have a relatively thick fault gouge, appear to have had a stronger control on the propagation of bedding-oblique faults than did the Last MM fault, which has a relatively thin fault gouge.

Syntectonic Mississippi River Channel Response: Integrating River Morphology and Seismic Imaging to Detect Active Faults

NASA Astrophysics Data System (ADS)

Magnani, M. B.

2017-12-01

Alluvial rivers, even great rivers such as the Mississippi, respond to hydrologic and geologic controls. Temporal variations of valley gradient can significantly alter channel morphology, as the river responds syntectonically to attain equilibrium. The river will alter its sinuosity, in an attempt to maintain a constant gradient on a surface that changes slope through time. Therefore, changes of river pattern can be the first clue that active tectonics is affecting an area of pattern change. Here I present geomorphological and seismic imaging evidence of a previously unknown fault crossing the Mississippi river south of the New Madrid seismic zone, between Caruthersville, Missouri and Osceola, Arkansas, and show that both datasets support Holocene fault movement, with the latest slip occurring in the last 200 years. High resolution marine seismic reflection data acquired along the Mississippi river imaged a NW-SE striking north-dipping fault displacing the base of the Quaternary alluvium by 15 m with reverse sense of movement. The fault consistently deforms the Tertiary, Cretaceous and Paleozoic formations. Historical river channel planforms dating back to 1765 reveal that the section of the river channel across the fault has been characterized by high sinuosity and steep projected-channel slope compared to adjacent river reaches. In particular, the reach across the fault experienced a cutoff in 1821, resulting in a temporary lowering of sinuosity followed by an increase between the survey of 1880 and 1915. Under the assumption that the change in sinuosity reflects river response to a valley slope change to maintain constant gradient, I use sinuosity through time to calculate the change in valley slope since 1880 and therefore to estimate the vertical displacement of the imaged fault in the past 200 years. Based on calculations so performed, the vertical offset of the fault is estimated to be 0.4 m, accrued since at least 1880. If the base of the river alluvium imaged here is coeval to that of the region just south (which was recently drilled and dated at 14.3 ka), and assuming a uniform slip accumulation through time, then 15 m of vertical offset imaged by the seismic data suggests a return interval of 400 years for this fault, comparable to the one observed for the nearby New Madrid seismic zone fault system.

Permeability and of the San Andreas Fault core and damage zone from SAFOD drill core

NASA Astrophysics Data System (ADS)

Rathbun, A. P.; Fry, M.; Kitajima, H.; Song, I.; Carpenter, B. M.; Marone, C.; Saffer, D. M.

2012-12-01

Quantifying fault-rock permeability is important toward understanding both the regional hydrologic behavior of fault zones, and poro-elastic processes that may affect faulting and earthquake mechanics by mediating effective stress. These include persistent fluid overpressures hypothesized to reduce fault strength, as well as dynamic processes that may occur during earthquake slip, including thermal pressurization and dilatancy hardening. To date, studies of permeability on fault rocks and gouge from plate-boundary strike-slip faults have mainly focused on samples from surface outcrops. We report on permeability tests conducted on the host rock, damage zone, and a major actively creeping fault strand (Central Deformation Zone, CDZ) of the San Andreas Fault (SAF), obtained from coring across the active SAF at ~2.7 km depth as part of SAFOD Phase III. We quantify permeability on subsamples oriented both perpendicular and parallel to the coring axis, which is nearly perpendicular to the SAF plane, to evaluate permeability anisotropy. The fault strand samples were obtained from the CDZ, which accommodates significant creep, and hosts ~90% of the observed casing deformation measured between drilling phases. The CDZ is 2.6 m thick with a matrix grain size < 10 μm and ~5% vol. clasts, and contains ~80% clay, of which ~90% is smectite. We also tested damage zone samples taken from adjacent core sections within a few m on either side of the CDZ. Permeability experiments were conducted in a triaxial vessel, on samples 25.4 mm in diameter and ~20-35 mm in length. We conducted measurements under isotropic stress conditions, at effective stress (Pc') of ~5-70 MPa. We measure permeability using a constant head flow-through technique. At the highest Pc', low permeability of the CDZ and damage zone necessitates using a step loading transient method and is in good agreement with permeabilities obtained from flow-through experiments. We quantify compression behavior by monitoring the volumetric and axial strain in response to changes in effective stress. Permeability of the CDZ is systematically lower than that of the damage zone or wall rock, and decreases from 2x10 -19m 2 at 5 MPa effective stress to 5x10-21 m 2 at 65 MPa. Some damage zone samples exhibit permeabilities as low as the CDZ, but most values are ~10-30 times higher. For both the damage zone and CDZ, permeability anisotropy is negligible. Volumetric compressibility (mv) decreases from ~1x10-9 Pa-1 to ~1x10-10 Pa-1 and hydraulic diffusivity decreases from ~2x10-7 m2/s to 1.7x10-8 m2/s over a range of effective stresses from 10 to 65 MPa. Our results are consistent with published geochemical data from SAFOD mud gas monitoring, and from inferred pore pressures during drilling [Zoback et al., 2010], which together suggest that the fault has a low permeability and is a barrier to regional fluid flow along. Our results also demonstrate that the diffusivity of the fault core of CDZ is sufficiently low to result in effectively undrained behavior over timescales of minutes to hours, thus facilitating dynamic hydrologic processes that may impact fault slip, including thermal pressurization and dilatancy hardening.

Initial report on drilling into seismogenic zones of M2.0 - M5.5 earthquakes from deep South African gold mines (DSeis)

NASA Astrophysics Data System (ADS)

Ogasawara, Hiroshi; Durrheim, Raymond; Yabe, Yasuo; Ito, Takatoshi; van Aswegen, Gerrie; Grobbelaar, Michelle; Funato, Akio; Ishida, Akimasa; Ogasawara, Hiroyuki; Mngadi, Siyanda; Manzi, Musa; Ziegler, Martin; Ward, Tony; Moyer, Pamela; Boettcher, Margaret; Ellsworth, Bill; Liebenberg, Bennie; Wechsler, Neta; Onstott, Tullis; Berset, Nicolas

2017-04-01

The International Continental Scientific Drilling Program (ICDP) approved our proposal (Ogasawara et al., EGU 2016) to drill into and around seismogenic zones where critically stressed faults initiated ruptures at depth. The drilling targets include four ruptures equivalent to M2.0, 2.8, 3.5, and 5.5 that dynamically and quasi-statically evolved in 2.9 Ga hard rock in the Witwatersrand basin, South Africa. Major advantages of our drilling locations are the large quantity and high-quality of existing data from dense seismic arrays both on surface and near-field underground in three deep South African gold mines. Additionally, the great depths (1.0 to 3.3 km from surface) to collar holes reduce drilling costs significantly and enable a larger number of holes to be drilled. Flexibility in drilling direction will also allow us to minimize damage in borehole or drilled cores. With the ICDP funds, we will conduct full-core drilling of 16 holes with drilling ranges from 50 to 750 m to recover both materials and fractures in and around the seismogenic zones, followed by core and borehole logging. Additional in-hole monitoring at close proximity will be supported by co-mingled funds and will follow the ICDP drilling. Expected magnitudes of maximum shear stress are several tens of MPa. We have established an overcoring procedure to measure 3D-stress state for adverse underground working conditions so as not to interfere with mining operations. This procedure was optimized based on the Compact Conic-ended Borehole Overcoring (CCBO) technique (ISRM suggested; Sugawara and Obara, 1999). Funato and Ito (2016 IJRMMS) developed a diametrical core deformation analysis (DCDA) method to measure differential stress using only drilled core by assuming diametrical change with roll angles caused by elastic in-axisymmetrical expansion during drilling. A gold mine has already drilled a hole to intersect the hypocenter of a 2016 M3.5 earthquake and carried out the CCBO stress measurement in other holes at the M3.5 seismogenic zone. As we successfully conducted DCDA with the above-mentioned drilled core, we look forward to shedding light on spatial variations of stress in the seismogenic zones following our ICDP DSeis drilling. A M5.5 earthquake which took place near Orkney, South Africa on 5 August 2014, offers a special opportunity to compare seismically inverted spatio-temporal evolution of both the main rupture and the aftershock activity with the information directly probed by the ICDP DSeis project. Moyer et al. (2016 Seismol. Res. Lett. submitted) calls for comparing seismic source models as part of a workshop proposed to the Southern California Earthquake Center for Fall 2017. In addition, the upper edge of the M5.5 rupture is located hundreds of meters below the mining horizon, sufficiently away from anthropogenic activity. This allows geomicrobiologists to investigate deep microbiological activity fueled by H2 from seismic rupture to address questions about Earth's early life. Drilling machines are being rigged underground soon to kick off our ICDP DSeis drilling in early 2017.

Virtual Research Expeditions along Plate Margins: Examples from an Online Oceanography Course

NASA Astrophysics Data System (ADS)

Reed, D. L.; Moore, G. F.; Bangs, N. L.; Tobin, H. J.

2010-12-01

An undergraduate online course in oceanography is based on the participation of each student in a series of virtual, at-sea, research expeditions, two of which are used to examine the tectonic processes at plate boundaries. The objective is to leverage the results of major federal research initiatives in the ocean sciences into effective learning tools with a long lifespan for use in undergraduate geoscience courses. These web-based expeditions examine: (1) hydrothermal vents along the divergent plate boundary at the Explorer Ridge and (2) the convergent plate boundary fault along the Nankai Trough, which is the objective of the multi-year NanTroSEIZE drilling program. Here we focus on the convergent plate boundary in NanTroSEIZE 3-D, which is based on a seismic survey supported through NSF-MARGINS, IODP and CDEX in Japan to study the properties of the plate boundary fault system in the upper limit of the seismogenic zone off Japan. The virtual voyage can be used in undergraduate classes at anytime, since it is not directly tied to the finite duration of a specific seagoing project, and comes in two versions, one that is being used in geoscience major courses and the other in non-major courses, such as the oceanography course mentioned above and a lower-division global studies course with a science emphasis. NanTroSEIZE in 3-D places undergraduate learning in an experiential framework as students participate on the expedition and carry out research on the structure of the plate boundary fault. Students learn the scientific background of the program, especially the critical role of international collaboration, and meet the chief scientists before joining the 3-D seismic imaging expedition to identify the active faults that were the likely sources of devastating earthquakes and tsunamis in Japan in 1944 and 1948. The initial results of phase I ODP drilling that began in 2007 are also reviewed. Students document their research on a worksheet that accompanies the expedition, interpret a slice through the 3-D seismic volume, and compose an “AGU-style” abstract summarizing their work, which is submitted to the instructor for review. NanTroSEIZE in 3-D is openly available and can be accessed through the MARGINS Mini-lesson section of the Science Education Resource Center (SERC).

Drill hole logging with infrared spectroscopy

USGS Publications Warehouse

Calvin, W.M.; Solum, J.G.

2005-01-01

Infrared spectroscopy has been used to identify rocks and minerals for over 40 years. The technique is sensitive to primary silicates as well as alteration products. Minerals can be uniquely identified based on multiple absorption features at wavelengths from the visible to the thermal infrared. We are currently establishing methods and protocols in order to use the technique for rapid assessment of downhole lithology on samples obtained during drilling operations. Initial work performed includes spectral analysis of chip cuttings and core sections from drill sites around Desert Peak, NV. In this paper, we report on a survey of 10,000 feet of drill cuttings, at 100 foot intervals, from the San Andreas Fault Observatory at Depth (SAFOD). Data from Blue Mountain geothermal wells will also be acquired. We will describe the utility of the technique for rapid assessment of lithologic and mineralogic discrimination.

Stratigraphy, structure, and some petrographic features of Tertiary volcanic rocks in the USW G-2 drill hole, Yucca Mountain, Nye County, Nevada

USGS Publications Warehouse

Maldonado, Florian; Koether, S.L.

1983-01-01

A continuously cored drill hole designated as USW G-2, located at Yucca Mountain in southwestern Nevada, penetrated 1830.6 m of Tertiary volcanic strata composed of abundant silicic ash-flow tuffs, minor lava and flow breccias, and subordinate volcaniclastic rocks. The volcanic strata penetrated are comprised of the following in descending order: Paintbrush Tuff (Tiva Canyon Member, Yucca Mountain Member, bedded tuff, Pah Canyon Member, and Topopah Spring Member), tuffaceous beds of Calico Hills, Crater Flat Tuff (Prow Pass Member, Bullfrog Member, and Tram unit), lava and flow breccia (rhyodacitic), tuff of Lithic Ridge, bedded and ash-flow tuff, lava and flow breccia (rhyolitic, quartz latitic, and dacitic), bedded tuff, conglomerate and ash-flow tuff, and older tuffs of USW G-2. Comparison of unit thicknesses at USW G-2 to unit thicknesses at previously drilled holes at Yucca Mountain indicate the following: (1) thickening of the Paintbrush Tuff members and tuffaceous beds of Calico Hills toward the northern part of Yucca Mountain; (2) thickening of the Prow Pass Member but thinning of the Bullfrog Member and Tram unit; (3) thinning of the tuff of Lithic Ridge; (4) presence of approximately 280 m of lava and flow breccia not previously penetrated by any drill hole; and (5) presence of an ash-flow tuff unit at the bottom of the drill hole not previously intersected, apparently the oldest unit penetrated at Yucca Mountain to date. Petrographic features of some of the units include: (1) decrease in quartz and K-feldspar and increases in biotite and plagioclase with depth in the tuffaceous beds of Calico Hills; (2) an increase in quartz phenocrysts from the top to the bottom members of the Crater Flat Tuff; (3) a low quartz content in the tuff of Lithic Ridge, suggesting tapping of the magma chamber at quartz-poor levels; (4) a change in zeolitic alteration from heulandite to clinoptilolite to mordenite with increasing depth; (5) lavas characterized by a rhyolitic top and dacitic base, suggesting reverse compositional zoning; and (6) presence of hydrothermal mineralization in the lavas that could be related to an intrusive under Yucca Mountain or to volcanism associated with the Timber Mountain-Claim Canyon caldera complex. A fracture analysis of the core resulted n tabulation of 7,848 fractures, predominately open and high angle. The fractures were filled or coated with material in various combinations and include the following in decreasing abundance: CaCo3, iron oxides and hydroxides, SiO2, manganese oxides and hydroxides, clays and zeolites. An increase in the intensity of fracturing can be correlated with the following: (1) densely welded zones, (2) lithophysal zones, (3) vitrophyre, (4) silicified zones, (5) fault zones, and (6) cooling joints. Numerous fault zones were penetrated by the drill hole, predominately in the lithophysal zone of the Topopah Spring Member and below the tuffaceous beds of Calico Hills. The faults are predominately high angle with both a vertical and lateral component. Three major faults were penetrated, two of which intersect the ground surface, with displacements of at least 20 m and possibly as much as 52 m. The faults and some fractures are probably related to the regional doming of the area associated with the volcanism-tectonism of the Timber Mountain-Claim Canyon caldera complex, and to Basin and Range tectonism.

Quantitative Analysis of Thermal Anomalies in the DFDP-2B Borehole, New Zealand

NASA Astrophysics Data System (ADS)

Janků-Čápová, Lucie; Sutherland, Rupert; Townend, John

2017-04-01

The DFDP-2B borehole, which was drilled in the Whataroa Valley, South Island, New Zealand in late 2014, provides a unique opportunity to study the conditions in the hanging wall of a plate boundary fault, the Alpine Fault, which is late in its seismic cycle. High geothermal gradient of > 125°C/km encountered in the borehole drew attention to the thermal structure of the valley, as well as of the Alpine Fault's hanging wall as a whole. A detailed analysis of temperature logs measured during drilling of the DFDP-2B borehole, reveals two distinct portions of the signal containing information on different processes. The long-wavelength portion of the temperature signal, i.e. the overall trend (hundreds of metres), reflects the response of the rock environment to the disturbance caused by drilling and permits an estimation of the thermal diffusivity of the rock based on the rate of temperature recovery. The short-wavelength (tens of metres to tens of centimetres) signal represents the local anomalies caused by lithological variations or, more importantly, by fluid flow into or out of the borehole along fractures. By analysing these distinct features, we can identify anomalous zones that manifest in other wireline data (resistivity, BHTV) and are likely attributable to permeable fractures. Here we present a novel method of quantitative analysis of the short-wavelength temperature anomalies. This method provides a precise and objective way to determine the position, width and amplitude of temperature anomalies and facilitates the interpretation of temperature logs, which is of a particular importance in estimation of flow in a fractured aquifer.

Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery

USGS Publications Warehouse

Carson, Bobb; Seke, Erol; Paskevich, Valerie F.; Holmes, Mark L.

1994-01-01

Point-discharge fluid expulsion on accretionary prisms is commonly indicated by diagenetic deposition of calcium carbonate cements and gas hydrates in near-surface (<10 m below seafloor; mbsf) hemipelagic sediment. The contrasting clastic and diagenetic lithologies should be apparent in side scan images. However, sonar also responds to variations in bottom slope, so unprocessed images mix topographic and lithologic information. We have processed GLORIA imagery from the Oregon continental margin to remove topographic effects. A synthetic side scan image was created initially from Sea Beam bathymetric data and then was subtracted iteratively from the original GLORIA data until topographic features disappeared. The residual image contains high-amplitude backscattering that we attribute to diagenetic deposits associated with fluid discharge, based on submersible mapping, Ocean Drilling Program drilling, and collected samples. Diagenetic deposits are concentrated (1) near an out-of-sequence thrust fault on the second ridge landward of the base of the continental slope, (2) along zones characterized by deep-seated strikeslip faults that cut transversely across the margin, and (3) in undeformed Cascadia Basin deposits which overlie incipient thrust faults seaward of the toe of the prism. There is no evidence of diagenetic deposition associated with the frontal thrust that rises from the dècollement. If the dècollement is an important aquifer, apparently the fluids are passed either to the strike-slip faults which intersect the dècollement or to the incipient faults in Cascadia Basin for expulsion. Diagenetic deposits seaward of the prism toe probably consist dominantly of gas hydrates.

Three-dimensional geologic model of the southeastern Espanola Basin, Santa Fe County, New Mexico

USGS Publications Warehouse

Pantea, Michael P.; Hudson, Mark R.; Grauch, V.J.S.; Minor, Scott A.

2011-01-01

This multimedia model and report show and describe digital three-dimensional faulted surfaces and volumes of lithologic units that confine and constrain the basin-fill aquifers within the Espanola Basin of north-central New Mexico. These aquifers are the primary groundwater resource for the cities of Santa Fe and Espanola, six Pueblo nations, and the surrounding areas. The model presented in this report is a synthesis of geologic information that includes (1) aeromagnetic and gravity data and seismic cross sections; (2) lithologic descriptions, interpretations, and geophysical logs from selected drill holes; (3) geologic maps, geologic cross sections, and interpretations; and (4) mapped faults and interpreted faults from geophysical data. Modeled faults individually or collectively affect the continuity of the rocks that contain the basin aquifers; they also help define the form of this rift basin. Structure, trend, and dip data not previously published were added; these structures are derived from interpretations of geophysical information and recent field observations. Where possible, data were compared and validated and reflect the complex relations of structures in this part of the Rio Grande rift. This interactive geologic framework model can be used as a tool to visually explore and study geologic structures within the Espanola Basin, to show the connectivity of geologic units of high and low permeability between and across faults, and to show approximate dips of the lithologic units. The viewing software can be used to display other data and information, such as drill-hole data, within this geologic framework model in three-dimensional space.

Quaternary geology of the DFDP-2 drill holes, Alpine Fault, New Zealand

NASA Astrophysics Data System (ADS)

Upton, P.; Cox, S.; Howarth, J. D.; Sutherland, R.; Langridge, R.; Barth, N. C.; Atkins, C.

2015-12-01

A 240 m-thick Quaternary sediment sequence in Whataroa Valley was much thicker than predicted before drilling. DFDP-2A and DFDP-2B were mostly drilled through the sequence by dual-rotary method using air or water circulation, returning cuttings bagged at 1 or 2 m sample intervals. Some sorting/bias and contamination occurred. Core was retrieved in DFDP-2A from 125-160 m, with highly variable recovery (0-100%) and mixed preservation/quality. The sequence is interpreted to comprise: fluvial-glacial gravels (0-58 m); grading downward into sandy lake delta sediments (59-77 m); overlying a monotonous sequence of lake mud and silts, with rare pebble-cobble diamictite (77-206 m); with a basal unit (206-240 m) containing coarse cobbles and boulders that may represent a distinct till/diamictite. Evidence has yet to be found for any marine influence in lowermost sediments, despite deposition at least 120 m below present day sea level, and potentially 200 m bsl if uplift has occurred on the Alpine Fault. When corrected for uplift the lacustrine sequence broadly correlates to those in present Lakes Rotokina and Wahapo, suggesting a substantial (~100 km2) pro-glacial lake once covered the area. Radiocarbon dating of plant fragments indicate 70 m of upper lacustrine and deltaic sediments (129-59 m) were deposited rapidly between 16350-15800 Cal BP. Overlying alluvial gravels are much younger (<1 ka), but potentially also involved pulses of rapid aggradation. The sequence provides a record of sedimentation on the Alpine Fault hanging wall following late-glacial ice retreat up Whataroa Valley, with uplift and erosion followed by Holocene alluvial gravel deposition. Future work will address: (1) the nature and history of sedimentation, including the lithology and origin of sediments; (2) what, if any, geological record of tectonics (movement) or Alpine Fault earthquakes (shaking) the sediments contain.

Vertical Seismic Profiling at riser drilling site in the rupture area of the 1944 Tonankai Earthquake, Japan (Invited)

NASA Astrophysics Data System (ADS)

Hino, R.; Kinoshita, M.; Araki, E.; Byrne, T. B.; McNeill, L. C.; Saffer, D. M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.

2009-12-01

A series of scientific drilling expeditions is in operation in the Nankai Trough to reveal the faulting mechanism of the magathrust earthquakes, through clarifying composition, fine structure, mechanical behavior, and environmental variables of the seismogenic faults. In the studied area, extensive seismic surveys for site characterization have been made to image detailed geometry of the fault complex in the accretionary prism as well as Vp distribution around the faults. Although these previous surveys provided invaluable information for understanding seismotectonic processes in this subduction zone, more complete knowledge is needed to be acquired to predict dynamic behavior of the faults, such as geometrical irregularities in short wavelength, Vs and seismic attenuation which are sensitive to fluid distribution in and around fault zones. It is expected that estimation of these parameters would be improved considerably by a seismic exploration using a vertical array of seismographs installed in a deep borehole (VSP: vertical seismic profiling). In July 2009, we made a VSP at one of the drilling sites located just above the rupture area of the 1994 Tonankai Earthquake (M 8.1), during the IODP Exp.319. The well site of our VSP was made by the riser drilling of D/V Chikyu. The seismic array, lowered from Chikyu into the hole, was composed of a three-component accelerometer and vertical separation of the array elements was 15.12 m. The VSP was composed of offset VSP and zero-offset VSP. In the offset VSP, a tuned airgun array towed by R/V Kairei was shot along one straight line (walk-away VSP) and another circular line (walk-around VSP) and seismic signals were recorded by an array consisting of 16 elements installed from 907 to 1,135 m in depth from seafloor. The object of the walk-away VSP is to obtain fine image of the faults using reflection arrivals with less attenuation. It is also expected to obtain spatial variation of Vs from arrival time tomography of refracted S waves. For this purpose, we preferred extraordinarily longer (~ 30 km) offset shooting than usual industrial VSPs. Shot spacing was 60 m along the same line as the previous 3D reflection and OBS wide angle surveys. The radius of circle of the walk-around VSP was 3.5 km to detect azimuthal anisotropy of downgoing P and S waves, correlated to stress state around the site. In zero-offset VSP, shots just above the hole were recorded by the 8 element array moving from 0 to 1,135 mbsf along the hole so that seismic structure with comparable vertical resolution as core-log information would be obtained. In the records of the walk-away VSP, clear first arrivals as well as several evident later arrivals were clearly identified. The later phases contain the reflection from the megasplay fault and the refracted S wave through the accretional prism, on both of which we have significant interest. The walk-around VSP also provided us with high S/N records but detailed data reduction, such as velocity analysis using vertical array, are required to derive anisotropic nature of the formation around the hole.

High resolution shallow imaging of the mega-splay fault in the central Nankai Trough off Kumano

NASA Astrophysics Data System (ADS)

Ashi, J.

2012-12-01

Steep slopes are continuously developed at water depths between 2200 to 2800 m at the Nankai accretionary prism off Kumano. These slopes are interpreted to be surface expressions caused by the megasplay fault on seismic reflection profiles. The fault plane has been drilled at multiple depths below seafloor by IODP NanTroSEIZE project. Mud breccias only recognized at the hanging wall of the fault (Site C0004) by Xray CT scanner are interpreted be formed by strong ground shaking and the age of the shallowest event of mud breccia layers suggests deformation in 1944 Tonankai earthquake (Sakaguchi et al., 2011). Detailed structures around the fault have been examined by seismic reflection profiles including 3D experiments. Although the fault plane deeper than 100 m is well imaged, the structure shallower than 100 m is characterized by obscure sediment veneer suggesting no recent fault activity. Investigation of shallow deformation structures is significant for understanding of recent tectonic activity. Therefore, we carried out deep towed subbottom profile survey by ROV NSS (Navigable Sampling System) during Hakuho-maru KH-11-9 cruise. We introduced a chirp subbottom profiling system of EdgeTech DW-106 for high resolution mapping of shallow structures. ROV NSS also has capability to take a long core with a pinpoint accuracy. The subbottom profiler crossing the megasplay fault near Site C0004 exhibits a landward dipping reflector suggesting the fault plane. The shallowest depth of the reflector is about 10 m below seafloor and the strata above it shows reflectors parallel to the seafloor without any topographic undulation. The fault must have displaced the shallow formation because intense deformation indicated by mud breccia was restricted to near fault zone. Slumping or sliding probably modified the shallow formation after the faulting. The shallow deformations near the megasplay fault were well imaged at the fault scarp 20 km southwest of Site C0004. Although the fault plane itself is not recognized, displacements of sedimentary layers are observed along the fault up to 30 meter below the seafloor. Landward dip of the fault is estimated to be 30 degrees. Displacements of strata are about 3 m near the surface and about 5 m at 7 m below the seafloor suggesting accumulation of fault displacement. The structure more than 30 m below the seafloor is obscure due to decrease of acoustic signal. Active cold seep is expected in this site by high heat flow (Yamano et al., 2012) and many trails of Calyptogena detected by seafloor observations. These results are consistent with the shallow structures reveled by our subbottom profiling survey. References Sakaguchi, A. et al., Geology 39, 919-922, 2011. Yamano, M. et al., JpGU Meeting abstract, SSS38-P23, 2012

Fault-related structural permeability: Qualitative insights of the damage-zone from micro-CT analysis.

NASA Astrophysics Data System (ADS)

Gomila, Rodrigo; Arancibia, Gloria; Nehler, Mathias; Bracke, Rolf; Stöckhert, Ferdinand

2016-04-01

Fault zones and their related structural permeability play a leading role in the migration of fluids through the continental crust. A first approximation to understanding the structural permeability conditions, and the estimation of its hydraulic properties (i.e. palaeopermeability and fracture porosity conditions) of the fault-related fracture mesh is the 2D analysis of its veinlets, usually made in thin-section. Those estimations are based in the geometrical parameters of the veinlets, such as average fracture density, length and aperture, which can be statistically modelled assuming penny-shaped fractures of constant radius and aperture within an anisotropic fracture system. Thus, this model is related to fracture connectivity, its length and to the cube of the fracture apertures. In this way, the estimated values presents their own inaccuracies owing to the method used. Therefore, the study of the real spatial distribution of the veinlets of the fault-related fracture mesh (3D), feasible with the use of micro-CT analyses, is a first order factor to unravel both, the real structural permeability conditions of a fault-zone, together with the validation of previous estimations made in 2D analyses in thin-sections. This early contribution shows the preliminary results of a fault-related fracture mesh and its 3D spatial distribution in the damage zone of the Jorgillo Fault (JF), an ancient subvertical left-lateral strike-slip fault exposed in the Atacama Fault System in northern Chile. The JF is a ca. 20 km long NNW-striking strike-slip fault with sinistral displacement of ca. 4 km. The methodology consisted of the drilling of vertically oriented plugs of 5 mm in diameter located at different distances from the JF core - damage zone boundary. Each specimen was, then, scanned with an x-ray micro-CT scanner (ProCon X-Ray CTalpha) in order to assess the fracture mesh. X-rays were generated in a transmission target x-ray tube with acceleration voltages ranging from 90-120 kV and target currents from 40-60 μA. The focal spot size on the diamond/tungsten target was about 5 μm. The x-ray beam was filtered using a 1 mm Aluminum plate before passing the sample. 1200 x-ray images were taken during a full rotation of the sample using an amorphous silicon flat panel detector with 1516x1900 pixels. This resulted in a voxel resolution of about 8 μm in the 3D data reconstructed from the images. Future work will be aimed in the images segmentation of the fault-related fracture mesh followed by the estimation of its hydraulic properties at the time of fracture sealing. Acknowledgements: This work is a contribution to the CONICYT- BMBF International Scientific Collaborative Research Program Project PCCI130025/FKZ01DN14033 and the FONDAP-CONICYT Project 15090013.

Quaternary displacement rates on the Meeman‐Shelby fault and Joiner ridge horst, eastern Arkansas: Results from coring Mississippi River alluvium

USGS Publications Warehouse

Ward, Alex; Counts, Ronald C.; Van Arsdale, Roy; Larsen, Daniel; Mahan, Shannon

2017-01-01

This research used coring and optically stimulated luminescence (OSL) dating of displaced, deeply buried Quaternary alluvium to determine vertical displacement rates for the Meeman‐Shelby fault and the Joiner ridge horst, two structures in northeastern Arkansas that have no modern seismicity associated with them. We drilled continuous cores of the entire alluvial section in the hanging wall of each structure, performed detailed core descriptions and analyses, and obtained three OSL ages from each core. The Meeman‐Shelby fault core consists of 36 m of 4.3–5.2‐ka Holocene alluvium overlying 4 m of 14.3‐ka Kennett alluvium that in turn overlies the upper part of Eocene Claiborne Group sediments at a depth of 41 m. Seismic reflection indicates that the basal (Kennett) alluvium at the Meeman‐Shelby fault is displaced ∼28  m across the Meeman‐Shelby fault, which equates to a time‐averaged vertical displacement rate of 2  mm/yr within the last 14.3 ka. The Joiner ridge horst core consists, in descending order, of 11 m of 6.3‐ka Holocene alluvium, 14 m of 11.5‐ka Morehouse alluvium, a paleosol, 6 m of Kennett alluvium, and 4 m of 20.3‐ka Sikeston alluvium that in turn overlies the upper part of Eocene Claiborne Group sediments at a depth of 36 m. Lignite exploration drilling conducted in the 1970s indicates that basal (Sikeston) alluvium is displaced ∼20  m across the eastern bounding fault of the Joiner ridge horst, resulting in a time‐averaged vertical displacement rate of ∼1  mm/yr within the last 20.3 ka. These late Quaternary displacement rates are comparable to time‐averaged displacement rates of faults within the active New Madrid seismic zone.

Geologic setting of the proposed West Flank Forge Site, California: Suitability for EGS research and development

USGS Publications Warehouse

Sabin, Andrew; Blake, Kelly; Lazaro, Mike; Blankenship, Douglas; Kennedy, Mack; McCullough, Jess; DeOreo, S.B.; Hickman, Stephen H.; Glen, Jonathan; Kaven, Joern; Williams, Colin F.; Phelps, Geoffrey; Faulds, James E.; Hinz, Nicholas H.; Calvin, Wendy M.; Siler, Drew; Robertson-Tait, Ann

2017-01-01

The proposed West Flank FORGE site is within the China Lake Naval Air Weapons Station (NAWS), China Lake, CA. The West Flank is west of the Coso geothermal field, an area of China Lake NAWS dominated by the Quaternary Coso volcanic field largely comprised of rhyolite domes and their volcaniclastic and epiclastic horizons. The largest dome flow complex, Sugarloaf Mountain, marks the northwestern margin of the geothermal field. The West Flank is situated due west of Sugarloaf. The geologic setting of the West Flank was determined from one deep well (83-11) drilled as a potential production hole in 2009. The bottom-hole temperature (BHT) of well 83-11 approaches 600 oF (315˚C), but flow tests demonstrate very low, non-commercial permeabilities. With the exception of the upper 600 feet of volcaniclastic alluvium, well 83-11 is completed in granitic basement. The West Flank possesses the primary attributes of a FORGE site: non-commercial permeability (<10-16m2), a 175˚ to 225˚C temperature range in crystalline rocks, and a location outside an existing geothermal fieldThe Coso Mountains host the Coso volcanic field and are within a right-releasing stepover between the dextral Airport Lake (ALF) and Little Lake fault zones (LLFZ) and the Wild Horse Mesa and Owens Valley faults. Two distinct fault populations have been identified at Coso: WNW-trending and antithetical, NE-trending strike-slip faults and N- to NNE-trending normal faults. These faults are both high permeability drilling targets at depth within the main (productive) geothermal field and they locally segment the field into distinct hydrothermal regimes. The West Flank may be segmented from the rest of the field by one such northerly trending fault. The overall minimum principal stress orientation in the main geothermal field varies from 103˚ to 108˚; however, the minimum horizontal principal stress in 83-11 is rotated to 081˚.

New insight into the 1556 M8 Huaxian earthquake in China

NASA Astrophysics Data System (ADS)

Ma, J.

2017-12-01

The disastrous 1556 M8 Huaxian earthquake in China took away 0.8Ma lives then as well as attracted scientists' attention. Although the Huashan front fault and Weinan plateform-front fault at the south margin of Weihe basin was responsible for this earthquake, we know less about the fault behaviors. There's evidence that the modern riverbank offset and older geomorphic scarps in Chishui river site on Weinan plateau-front fault from the Pleiades DEM. Here, we did a 3D trench excavation model using SfM work, drilling profiles and geomorphological measurement there to revive the site for multiearthquakes. It turns out two events occurred on the normal fault with pretty high offsets 9.4m and 7.8-8.0m respectively, the later one resulted from Huaxian earthquake. And we estimate that the fault slip rate approximately 1.48-1.75 mm/a. Thus, we find that the older earthquake also produced a similar fault offsets to the 1556 earthquake showing as characteristics earthquake. The paleoseismic study demonstrates that the Weinan pateform-front fault plays a role in boundary faults of Weihe basin, which can contribute to the basin evolution of regions of active faulting.

Petrology of deep drill hole, Kilauea Volcano

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grose, L.T.; Keller, G.V.

1976-12-01

The first deep drill hole (1262 m TD) at the summit of an active volcano (1102 m elev) was drilled in 1973 at Kilauea volcano, Hawaii with support from NSF and USGS. The hole is located within southern margin of Kilauea caldera in northern part of a 15 km/sup 2/ triangular block bounded by east rift zone, Koae fault zone, and southwest rift zone-a summit area relatively free of faults, rifts, and extrusions. Nearest eruptions are from fissures 1.2 km away which are active in 1974 and which do not trend toward the drill hole. Core recovery totals 47 mmore » from 29 core runs at rather evenly spaced intervals to total depth. Megascopic, thin-section, and X-ray examination reveals: (1) Recovered core is essentially vesicular, intergranular, nonporphyritic to porphyritic olivine basalt with minor olivine diabase, picrite diabase, and basalt, (2) Hyaloclastite and pillow basalt are absent, (3) Below water table (614 m elev) with increasing depth, vesicularity decreases, and density, crystallinity, competence, vesicle fill, and alteration irregularly increase, (4) Alteration first occurs at water table where calcite and silica partially fill vesticles and olivine is partially serpentinized, (5) At about 570 m elev massive serpentinization of olivine and deposition of montmorillonite-nontronite occur; at about 210 m elev truscottite and tobermorite occur in vesicles; at about 35 m elev mordenite occurs in vesicles, (6) Bottom-hole cores have complete filling of vesicles with silica, minor silica replacement, and complete alteration of olivine, and (7) Plagioclase is unaltered. Chemical analyses of bottom-hole cores are similar to those of modern summit lavas. Alteration and low porosity in bottom-hole cores plus abrupt temperature increase suggest the drill hole penetrated a self-sealed ''cap rock'' to a hydrothermal convection cell and possibly a magma body.« less

The effects of the Yogyakarta earthquake at LUSI mud volcano, Indonesia

NASA Astrophysics Data System (ADS)

Lupi, M.; Saenger, E. H.; Fuchs, F.; Miller, S. A.

2013-12-01

The M6.3 Yogyakarta earthquake shook Central Java on May 27th, 2006. Forty seven hours later, hot mud outburst at the surface near Sidoarjo, approximately 250 km from the earthquake epicentre. The mud eruption continued and originated LUSI, the youngest mud volcanic system on earth. Since the beginning of the eruption, approximately 30,000 people lost their homes and 13 people died due to the mud flooding. The causes that initiated the eruption are still debated and are based on different geological observations. The earthquake-triggering hypothesis is supported by the evidence that at the time of the earthquake ongoing drilling operations experienced a loss of the drilling mud downhole. In addition, the eruption of the mud began only 47 hours after the Yogyakarta earthquake and the mud reached the surface at different locations aligned along the Watukosek fault, a strike-slip fault upon which LUSI resides. Moreover, the Yogyakarta earthquake also affected the volcanic activity of Mt. Semeru, located as far as Lusi from the epicentre of the earthquake. However, the drilling-triggering hypothesis points out that the earthquake was too far from LUSI for inducing relevant stress changes at depth and highlight how upwelling fluids that reached the surface first emerged only 200 m far from the drilling rig that was operative at the time. Hence, was LUSI triggered by the earthquake or by drilling operations? We conducted a seismic wave propagation study on a geological model based on vp, vs, and density values for the different lithologies and seismic profiles of the crust beneath LUSI. Our analysis shows compelling evidence for the effects produced by the passage of seismic waves through the geological formations and highlights the importance of the overall geological structure that focused and reflected incoming seismic energy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

F.V. Perry

Basaltic volcanism poses a potential hazard to the proposed Yucca Mountain nuclear waste repository because multiple episodes of basaltic volcanism have occurred in the Yucca Mountain region (YMR) in the past 11 Ma. Intervals between eruptive episodes average about 1 Ma. Three episodes have occurred in the Quaternary at approximately 1.1 Ma (5 volcanoes), 350 ka (2 volcanoes), and 80 ka (1 volcano). Because Yucca Mountain lies within the Basin and Range Province, a significant portion of the pre-Quaternary volcanic history of the YMR may be buried in alluvial-filled basins. An exceptionally high-resolution aeromagnetic survey and subsequent drilling program sponsoredmore » by the U.S. Department of Energy (DOE) began in 2004 and is gathering data that will enhance understanding of the temporal and spatial patterns of Pliocene and Miocene volcanism in the region (Figure 1). DOE has convened a ten-member expert panel of earth scientists that will use the information gathered to update probabilistic volcanic hazard estimates originally obtained by expert elicitation in 1996. Yucca Mountain is a series of north-trending ridges of eastward-tilted fault blocks that are bounded by north to northeast-trending normal faults. Topographic basins filled with up to 500 m of alluvium surround it to the east, south and west. In the past several decades, nearly 50 holes have been drilled in these basins, mainly for Yucca Mountain Project Site Characterization and the Nye County Early Warning Drilling Program. Several of these drill holes have penetrated relatively deeply buried (300-400 m) Miocene basalt; a Pliocene basalt dated at 3.8 Ma was encountered at a relatively shallow depth (100 m) in the northern Amargosa Desert (Anomaly B in Figure 1). The current drilling program is the first to specifically target and characterize buried basalt. Based on the new aeromagnetic survey and previous air and ground magnetic surveys (Connor et al. 2000; O'Leary et al. 2002), at least eight drill holes are planned with the goal of sampling each geographic subpopulation of magnetic anomalies in the region (Figure 1). This will result in a more complete characterization of the location, age, volume and composition of buried basaltic features for the purpose of updating the volcanic hazard assessment. Smith and Keenan (2005) suggested that volcanic hazard estimates might be 1-2 orders of magnitude higher than estimated by the DOE expert elicitation in 1996, based on (1) a proposed relationship between recurrence rates in the YMR and the Reveille-Lunar Crater volcanic field to the north, and (2) the implication that a number of so-far-undiscovered buried volcanoes would have a significant impact on hazard estimates. This article presents the new aeromagnetic data and an interpretation of the data that suggests magnetic anomalies nearest the proposed repository site represent buried Miocene basalt that will likely have only a minor impact on the volcanic hazard.« less

The Comparison Study of gas source between two hydrate expeditions in ShenHu area, SCS

NASA Astrophysics Data System (ADS)

Cong, X. R.

2016-12-01

Two gas hydrate expeditions (GMGS 01&03) were conducted in the Pearl River Mouth Basin, SCS, which were organized by Guangzhou Marine Geological Survey in 2007 and 2015, respectively. Compared with the drilling results of "mixed bio-thermogenic gas and generally dominated by biogenic gas" in 2007, hydrocarbon component measurements revealed a higher content of ethane and propane in 2015 drilling, providing direct evidence that deep thermogenic gas was the source for shallow hydrate formation. According to the geochemical analyses of the results obtained from the industrial boreholes in Baiyun sag, the deep hydrocarbon gas obviously leaked from the reservoir as escape caused by Dongsha movement in the late Miocene, as a result thermogenic gas from Wenchang, Enping and Zhuhai hydrocarbon source rocks migrated to late Miocene shallow strata through faults, diapirs and gas chimney vertically migration. In this paper we report the differences in fluid migration channel types and discuss their effect in fluid vertical migration efficiency in the two Shenhu hydrate drilling areas. For the drilling area in 2007,when the limited deep thermogenic gas experienced long distance migration process from bottom to up along inefficient energy channel, the gas composition might have changed and the carbon isotope fractionation might have happened, which were reflected in the results of higher C1/C2 ratios and lighter carbon isotope in gas hydrate bearing sediments. As a result the gas is with more "biogenic gas" features. It means thermogenic gases in the deep to contributed the formation of shallow gas hydrate indirectly in 2007 Shenhu drill area. On another hand, the gases were transported to the shallow sediment layers efficiently, where gas hydrate formed, through faults and fractures from deep hydrocarbon reservoirs, and as the result they experienced less changes in both components and isotopes in 2015 drilling site.

Combined geophysical, geochemical and geological investigations of geothermal reservoir characteristics in Lower Saxony, Germany

NASA Astrophysics Data System (ADS)

Hahne, B.; Thomas, R.

2012-04-01

The North German basin provides a significant geothermal potential, although temperature gradients are moderate. However, deep drilling up to several thousand meters is required to reach temperatures high enough for efficient generation of geothermal heat and electric power. In these depths we have not much information yet about relevant physical properties like porosity or permeability of the rock formations. Therefore the costs of developing a geothermal reservoir and the risk of missing the optimum drilling location are high. The collaborative research association "Geothermal Energy and High Performance Drilling" (gebo) unites several universities and research institutes in Lower Saxony, Germany. It aims at a significant increase of economic efficiency by introducing innovative technology and high tech materials resisting temperatures up to 200 °C in the drilling process. Furthermore, a better understanding of the geothermal reservoir is essential. gebo is structured into four main fields: Drilling Technology, Materials, Technical Systems and Geosystem. Here, we show the combined work of the Geosystem group, which focuses on the exploration of geological fault zones as a potential geothermal reservoir as well as on modeling the stress field, heat transport, coupled thermo-hydro-mechanical processes, geochemical interactions and prediction of the long-term behavior of the reservoir. First results include combined seismic and geoelectric images of the Leinetalgraben fault system, a comparison of seismic images from P- and S-wave measurements, mechanical properties of North German rocks from field and laboratory measurements as well as from drill cores, seismological characterization of stimulated reservoirs, a thermodynamic "gebo" database for modeling hydrogeochemical processes in North German formation waters with high salinity and at high temperatures, stress models for specific sites in northern Germany, and modeling results of permeability and heat transport in different (fractured) media. gebo is funded by the Ministry of Science and Culture of Lower Saxony, Germany and the industry partner Baker Hughes, Celle, Germany.

Southeastern extension of the Lake Basin fault zone in south- central Montana: implications for coal and hydrocarbon exploration ( USA).

USGS Publications Warehouse

Robinson, L.N.; Barnum, B.E.

1986-01-01

The Lake Basin fault zone consists mainly of en echelon NE-striking normal faults that have been interpreted to be surface expressions of left-lateral movement along a basement wrench fault. Information gathered from recent field mapping of coal beds and from shallow, closely-spaced drill holes resulted in detailed coal bed correlations, which revealed another linear zone of en echelon faulting directly on the extended trend of the Lake Basin fault zone. This faulted area, referred to as the Sarpy Creek area, is located 48 km E of Hardin, Montana. It is about 16 km long, 13 km wide, and contains 21 en echelon normal faults that have an average strike of N 63oE. We therefore extend the Lake Basin fault zone 32 km farther SE than previously mapped to include the Sarpy Creek area. The Ash Creek oil field, Wyoming, 97 km due S of the Sarpy Creek area, produces from faulted anticlinal structues that have been interpreted to be genetically related to the primary wrench-fault system known as the Nye-Bowler fault zone. The structural similarities between the Sarpy Creek area and the Ash Creek area indicate that the Sarpy Creek area is a possible site for hydrocarbon accumulation.-from Authors

The occurrence of macro- and mesoscopic methane hydrate in the eastern margin of Japan Sea

NASA Astrophysics Data System (ADS)

Matsumoto, R.; Kakuwa, Y.; Tanahashi, M.; Hiruta, A.

2016-12-01

Shallow methane hydrate is known to occur in muddy sediments that were deposited in the eastern margin of Japan Sea. In such settings, the hydrate occurs just below the seabed or is exposed directly on the seabed. Its presence is quite different from the pore-filling type of hydrate typically found in sandstone of the Pacific Ocean side of the Japanese islands. This presentation focuses on categorizing the distribution of gas hydrate in Japan Sea which, until recently, has been poorly understood. Macroscopic occurrence: Numerous gas chimney structures, which are characterized by an acoustic blanking on sub-bottom profiler images, have been discovered in the eastern margin of Japan Sea. We carried out seafloor drilling at several topographic highs that showed gas chimney structures. The results confirm that, while methane hydrate does not occur in the well-stratified part of SBP images, it does occur uniquely in the gas chimney structure-bearing mounds and pockmarks. Several horizons of methane hydrate-concentrated layers are identified by our LWD data and are traceable over lateral distances of as much as a kilometer.. In another case, the methane hydrate-concentrated layers occur stratigraphically in a regular manner with methane-derived carbonate nodules. We interpret the second case as one in which methane gas was supplied by regularly repeated movements of active fault(s). Mesoscopic occurrence: Methane hydrate is classified into 5 types that are readily observable in drilled cores: granular, nodular, platy, veiny and massive. The granular type is common over shallower intervals, while platy and veiny types are more common in the deeper intervals. Nevertheless, a significant fraction of the granular type may have possibly originated from the destruction and dissociation of other types during drilling and recovery. The massive type hydrate that characterizes highly-concentrated layers transitions to other types laterally as methane hydrate becomes poorly concentrated. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

Fluid Characteristics and Evolution of Chelungpu fault of Taiwan

NASA Astrophysics Data System (ADS)

Song, S. R.

2017-12-01

We analyzed geochemical characteristics, such as hydrogen and oxygen isotopes, and ionic concentrations, of fluid samples retrieved from various depth along boreholes of the Hole A and Hole B of Taiwan Chelungpu fault Drilling Project(TCDP) to trace the fluid sources. The results show that the source of fluid in the Hole B is mainly the tap water, while there are two probable sources in the Hole A owing to the abrupt shift of ionic concentrations at the depth of 200-300 m. The shallower fluid might be from the leakage above the depth of 300 m and is characteristic of lower ionic concentrations and the isotopic ratios are close to those of adjacent river water. However, the deeper fluid should be the thermal water from Kueichulin formation because of high ionic concentrations, especially HCO3-, and higher oxygen isotope, which suggests higher temperature and more isotope exchange. Two sources of fluid of the Hole A are representative of the fluid systems in the hanging wall and foot wall respectively. The characteristics of fluids in the Hole A imply that the fault zone serves as a barrier in the inter-seismic period, resulting in distinctly different fluid between the Hanging wall and the foot wall. The frequent occurrence and the distribution of calcite veins provide the evidence of the upwelling of HCO3-rich fluid of Kueichulin formation and indicate that the fault served as fluid conduit during faulting and allowed the fluid flow across the fault zone to precipitate calcite veins in fractures of the hanging wall. Thus, we can deduce the mechanism of local groundwater flow during different stages of fault development by evidences such as calcite veins distribution, regional groundwater geology, and fluids characteristics in boreholes of the Hole-A and Hole B. During inter-seismic period, groundwater flows below and above the fault zone are separated by the impermeable fault gouge layer. In co-seismic time, faulting breaks the gouge layer, providing openings that let the over-pressured thermal water which contained high concentration of bicarbonate ion to surge up. After co-seismic period, the gouge layer is sealed again, residual thermal water which contained high concentration of bicarbonate ion in the hanging wall gradually precipitated calcite in fractures and the closer precipitation took place, the more calcite veins.

AGSM Functional Fault Models for Fault Isolation Project

NASA Technical Reports Server (NTRS)

Harp, Janicce Leshay

2014-01-01

This project implements functional fault models to automate the isolation of failures during ground systems operations. FFMs will also be used to recommend sensor placement to improve fault isolation capabilities. The project enables the delivery of system health advisories to ground system operators.

Engineering report on drilling in the San Rafael Swell area, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, L.I.

1980-05-01

The San Rafael Swell drilling project was conducted by Bendix Field Engineering Corporation in support of the US Department of Energy National Uranium Resource Evaluation (NURE) program. This project consisted of 27 drill holes ranging in depth from 120.0 ft (36.5 m) to 3,700.0 ft (1,127.7 m). A total of 41,716 ft (12,715 m) was drilled, of which 3,099.8 ft (944.8 m) were cored. Geophysical logging was supplied by Century Geophysical Corporation and Bendix Field Engineering Corporation. The objective of the project was to test the uranium potential of the Triassic and Jurassic sandstone units and to investigate areas wheremore » industry was unlikely to drill in the near future. Drilling commenced September 24, 1978, and was finished on December 17, 1979.« less

Thoughts Regarding the Dimensions of Faults at Rainier and Aqueduct Mesas, Nye County, Nevada, Based on Surface and Underground Mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drellack, S.L.; Prothro, L.B.; Townsend, M.J.

2011-02-01

The geologic setting and history, along with observations through 50 years of detailed geologic field work, show that large-displacement (i.e., greater than 30 meters of displacement) syn- to post-volcanic faults are rare in the Rainier Mesa area. Faults observed in tunnels and drill holes are mostly tight, with small displacements (most less than 1.5 meters) and small associated damage zones. Faults are much more abundant in the zeolitized tuffs than in the overlying vitric tuffs, and there is little evidence that faults extend downward from the tuff section through the argillic paleocolluvium into pre-Tertiary rocks. The differences in geomechanical characteristicsmore » of the various tuff lithologies at Rainier Mesa suggest that most faults on Rainer Mesa are limited to the zeolitic units sandwiched between the overlying vitric bedded tuffs and the underlying pre-Tertiary units (lower carbonate aquifer–3, lower clastic confining unit–1, and Mesozoic granite confining unit).« less

Heterogeneities of mechanical properties in potential geothermal reservoir rocks of the North German Basin

NASA Astrophysics Data System (ADS)

Reyer, D.; Philipp, S. L.

2012-04-01

Heterogeneous rock properties in terms of layering and complex infrastructure of fault zones are typical phenomena in sedimentary basins such as the North German Basin. To be able to model reservoir stimulation in layered stratifications and to better adapt the drilling strategy to the rock mechanical conditions it is important to have knowledge about the effects of heterogeneous rock properties on fracture propagation and fault zone infrastructure for typical sedimentary reservoir rocks in the North German Basin. Therefore we aim at quantifying these properties by performing structural geological field studies in outcrop analogues combined with laboratory analyses. The field studies in Rotliegend sandstones (Lower Permian), the sandstones of the Middle Bunter (Lower Triassic) and the sandstones of the Upper Keuper (Upper Triassic) focus on 1) host rock fracture systems and 2) fault zone infrastructure. We analyse quantitatively the dimension, geometry, persistence and connectivity of fracture systems separately for host rocks and fault damage zones. The results show that in rocks with distinctive layering (sandstones and shales) natural fractures are often restricted to individual layers, that is, they are stratabound. The probability of fracture arrest seems to depend on the stiffness contrast between the two layers and on the thickness of the softer layer. The field studies are complemented by systematic sampling to obtain mechanical property variations caused by the layering. For the samples we measure the parameters Young's modulus, compressive and tensile strengths, elastic strain energy, density and porosity. The results show that the mechanical properties vary considerably and many samples are clearly anisotropic. That is, samples taken perpendicular to layering commonly have higher strengths but lower stiffnesses than those taken parallel to layering. We combine the results of laboratory analyses and field measurements to specify the mechanical heterogeneities of the sedimentary reservoir rocks of the North German Basin and of the mechanical units of fault zones therein. To estimate the in situ rock properties at different depths it is further important to understand how rocks from outcrops differ from rocks at depth (for example due to alteration and removal of the overburden load). To answer these questions we analyse samples from drill cores from depths relevant for the use as geothermal reservoirs which are stratigraphically and lithologically equivalent to those taken in outcrop analogues. The results from drill-core sample analyses are then compared with the results from the outcrop samples. Another approach is to analyse how rock mechanical properties correlate with petrographic properties (e.g., mineral content, cementation, fabric, porosity) to use this knowledge to extrapolate the data to depth. Altogether these results will be very useful to make better assumptions on natural reservoir permeabilities and to better adapt the drilling and reservoir stimulation strategy to the rock mechanical conditions.

Review-Esso Resources Canada Ltd. , Norman Wells expansion project drilling program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaef, D.G.

Esso Resources Canada Limited has embarked on a project to increase production from its Norman Wells Oil field located 145 km south of the Arctic Circle, from 475 m/sup 3//D to 4000 m/sup 3//D of crude oil. This paper provides details on the development drilling portion of the project which is comprised of 150 wells to be drilled in 3 years utilizing 2 drilling rigs from July 1982 through September 1985. The majority of the wells will be directionally drilled from multiwell land pads and artificial islands to shallow reservoir targets underlying the Mackenzie River, a major river intersecting themore » field boundaries. Experience from the initial 27 wells completed is provided.« less

Advanced Ground Systems Maintenance Functional Fault Models For Fault Isolation Project

NASA Technical Reports Server (NTRS)

Perotti, Jose M. (Compiler)

2014-01-01

This project implements functional fault models (FFM) to automate the isolation of failures during ground systems operations. FFMs will also be used to recommend sensor placement to improve fault isolation capabilities. The project enables the delivery of system health advisories to ground system operators.

Gas Hydrate Research Site Selection and Operational Research Plans

NASA Astrophysics Data System (ADS)

Collett, T. S.; Boswell, R. M.

2009-12-01

In recent years it has become generally accepted that gas hydrates represent a potential important future energy resource, a significant drilling and production hazard, a potential contributor to global climate change, and a controlling factor in seafloor stability and landslides. Research drilling and coring programs carried out by the Ocean Drilling Program (ODP), the Integrated Ocean Drilling Program (IODP), government agencies, and several consortia have contributed greatly to our understanding of the geologic controls on the occurrence of gas hydrates in marine and permafrost environments. For the most part, each of these field projects were built on the lessons learned from the projects that have gone before them. One of the most important factors contributing to the success of some of the more notable gas hydrate field projects has been the close alignment of project goals with the processes used to select the drill sites and to develop the project’s operational research plans. For example, IODP Expedition 311 used a transect approach to successfully constrain the overall occurrence of gas hydrate within the range of geologic environments within a marine accretionary complex. Earlier gas hydrate research drilling, including IODP Leg 164, were designed primarily to assess the occurrence and nature of marine gas hydrate systems, and relied largely on the presence of anomalous seismic features, including bottom-simulating reflectors and “blanking zones”. While these projects were extremely successful, expeditions today are being increasingly mounted with the primary goal of prospecting for potential gas hydrate production targets, and site selection processes designed to specifically seek out anomalously high-concentrations of gas hydrate are needed. This approach was best demonstrated in a recently completed energy resource focused project, the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II (GOM JIP Leg II), which featured the collection of a comprehensive set of logging-while-drilling (LWD) data through expected gas-hydrate-bearing sand reservoirs in seven wells at three sites in the Gulf of Mexico. The discovery of thick hydrate-bearing sands at two of the sites drilled in the Gulf Mexico validated the integrated geological and geophysical approach used in the pre-drill site selection process to identify gas hydrate reservoirs that may be conducive to energy production. The results of the GOM JIP Leg II LWD expedition are also being used to support the selection of sites for a future drilling, logging, and coring program. Operationally, recent drilling programs, such as ODP Leg 204, IODP Expedition 311, the Japanese Toaki-oki to Kumano-nada drilling leg, the Indian NGHP Expedition 01, and the South Korean Gas Hydrate Research and Development Organization Expedition 01 have demonstrated the great benefit of a multi-leg drilling approach, including the initial acquisition of LWD data that was used to then select sites for the drilling of complex core and wireline logging test holes. It is obvious that a fully integrated site selection approach and a “goal based” operational plan, possibly including numerous drill sites and drilling legs, are required considerations for any future gas hydrate research project.

Paleomagnetic and Magnetostratigraphic Studies in Drilling Projects of Impact Craters - Recent Studies, Challenges and Perspectives

NASA Astrophysics Data System (ADS)

Fucugauchi, J. U.; Velasco-Villarreal, M.; Perez-Cruz, L. L.

2013-05-01

Paleomagnetic studies have long been successfully carried out in drilling projects, to characterize the borehole columns and to investigate the subsurface structure and stratigraphy. Magnetic susceptibility logging and magnetostratigraphic studies provide data for lateral correlation, formation evaluation, azimuthal core orientation, physical properties, etc., and are part of the tools available in the ocean and continental drilling programs. The inclusion of continuous core recovery in scientific drilling projects have greatly expanded the range of potential applications of paleomagnetic and rock magnetic studies, by allowing laboratory measurements on core samples. For this presentation, we concentrate on drilling studies of impact structures and their usefulness for documenting the structure, stratigraphy and physical properties at depth. There are about 170-180 impact craters documented in the terrestrial record, which is a small number compared to what is observed in the Moon, Mars, Venus and other bodies of the solar system. Of the terrestrial impact craters, only a few have been studied by drilling. Some craters have been drilled as part of industry exploration surveys and/or academic projects, including notably the Sudbury, Ries, Vredefort, Manson and many other craters. As part of the Continental ICDP program, drilling projects have been conducted on the Chicxulub, Bosumtwi, Chesapeake and El gygytgyn craters. Drilling of terrestrial craters has proved important in documenting the shallow stratigraphy and structure, providing insight on the cratering and impact dynamics. Questions include several that can only be addressed by retrieving core samples and laboratory analyses. Paleomagnetic, rock magnetic and fabric studies have been conducted in the various craters, which are here summarized with emphasis on the Chicxulub crater and Yucatan carbonate platform. Chicxulub is buried under a kilometer of younger sediments, making drilling an essential tool. Oil exploration included several boreholes, and additionally we have drilled 11 boreholes with continuous core recovery. Contributions and limitations of paleomagnetism for investigating the impact age, crater stratigraphy, cratering, ejecta emplacement, impact dynamics, hydrothermal system and post-impact processes are discussed.

In situ stress and fracture permeability along the Stillwater fault zone, Dixie Valley Nevada

USGS Publications Warehouse

Hickman, S.H.; Barton, C.A.; Zoback, M.D.; Morin, R.; Sass, J.; Benoit, R.

1997-01-01

Borehole televiewer and hydrologic logging and hydraulic fracturing stress measurements were carried out in a 2.7-km-deep geothermal production well (73B-7) drilled into the Stillwater fault zone. Precision temperature and spinner flowmeter logs were also acquired in well 73B-7, with and without simultaneously injecting water into the well. Localized perturbations to well-bore temperature and flow were used to identify hydraulically conductive fractures. Comparison of these data with fracture orientations from the televiewer log indicates that permeable fractures within and adjacent to the Stillwater fault zone are critically stressed, potentially active shear planes in the current west-northwest extensional stress regime at Dixie Valley.

Characterizing structures on borehole images and logging data of the Nankai trough accretionary prism: new insights

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose

2016-04-01

IODP has extensively used the D/V Chikyu to drill the Kumano portion of the Nankai Trough, including two well sites within the Kumano Basin. IODP Expeditions 338 and 348 drilled deep into the inner accretionary prism south of the Kii Peninsula collecting a suite of LWD data, including natural gamma ray, electrical resistivity logs and borehole images, suitable to characterize structures (fractures and faults) inside the accretionary prism. Structural interpretation and analysis of logging-while-drilling data in the deep inner prism revealed intense deformation of a generally homogenous lithology characterized by bedding that dips steeply (60-90°) to the NW, intersected by faults and fractures. Multiple phases of deformation are characterized. IODP Expedition borehole images and LWD data acquired in the last decade in previous and results of NantroSEIZE IODP Expeditions (314, 319) were also analyzed to investigate the internal geometries and structures of the Nankai Trough accretionary prism. This study focused mainly on the characterization of the different types of structures and their specific position within the accretionary prism structures. New structural constraints and methodologies as well as a new approach to the characterization of study of active structures inside the prism will be presented.

Uncovering a Salt Giant. Deep-Sea Record of Mediterranean Messinian Events (DREAM) multi-phase drilling project

NASA Astrophysics Data System (ADS)

Camerlenghi, Angelo; Aoisi, Vanni; Lofi, Johanna; Hübscher, Christian; deLange, Gert; Flecker, Rachel; Garcia-Castellanos, Daniel; Gorini, Christian; Gvirtzman, Zohar; Krijgsman, Wout; Lugli, Stefano; Makowsky, Yizhaq; Manzi, Vinicio; McGenity, Terry; Panieri, Giuliana; Rabineau, Marina; Roveri, Marco; Sierro, Francisco Javier; Waldmann, Nicolas

2014-05-01

In May 2013, the DREAM MagellanPlus Workshop was held in Brisighella (Italy). The initiative builds from recent activities by various research groups to identify potential sites to perform deep-sea scientific drilling in the Mediterranean Sea across the deep Messinian Salinity Crisis (MSC) sedimentary record. In this workshop three generations of scientists were gathered: those who participated in formulation of the deep desiccated model, through DSDP Leg 13 drilling in 1973; those who are actively involved in present-day MSC research; and the next generation (PhD students and young post-docs). The purpose of the workshop was to identify locations for multiple-site drilling (including riser-drilling) in the Mediterranean Sea that would contribute to solve the several open questions still existing about the causes, processes, timing and consequences at local and planetary scale of an outstanding case of natural environmental change in the recent Earth history: the Messinian Salinity Crisis in the Mediterranean Sea. The product of the workshop is the identification of the structure of an experimental design of site characterization, riser-less and riser drilling, sampling, measurements, and down-hole analyses that will be the core for at least one compelling and feasible multiple phase drilling proposal. Particular focus has been given to reviewing seismic site survey data available from different research groups at pan-Mediterranean basin scale, to the assessment of additional site survey activity including 3D seismics, and to ways of establishing firm links with oil and gas industry. The scientific community behind the DREAM initiative is willing to proceed with the submission to IODP of a Multi-phase Drilling Project including several drilling proposals addressing specific drilling objectives, all linked to the driving objectives of the MSC drilling and understanding . A series of critical drilling targets were identified to address the still open questions related to the MSC event. Several proposal ideas also emerged to support the Multi-phase drilling project concept: Salt tectonics and fluids, Deep stratigraphic and crustal drilling in the Gulf of Lion (deriving from the GOLD drilling project), Deep stratigraphic and crustal drilling in the Ionian Sea, Deep Biosphere, Sapropels, and the Red Sea. A second MagellanPlus workshop held in January 2014 in Paris (France), has proceeded a step further towards the drafting of the Multi-phase Drilling Project and a set of pre-proposals for submission to IODP.

Improved 3D seismic images of dynamic deformation in the Nankai Trough off Kumano

NASA Astrophysics Data System (ADS)

Shiraishi, K.; Moore, G. F.; Yamada, Y.; Kinoshita, M.; Sanada, Y.; Kimura, G.

2016-12-01

In order to improve the seismic reflection image of dynamic deformation and seismogenic faults in the Nankai trough, the 2006 Kumano 3D seismic dataset was reprocessed from the original field records by applying advanced technologies a decade after the data acquisition and initial processing. The 3D seismic survey revealed the geometry of megasplay fault system. However, there were still unclear regions in the accretionary prism beneath from Kumano basin to the outer ridge, because of sea floor multiple reflections and noise caused by the Kuroshio current. For the next stage of deep scientific drilling into the Nankai trough seismogenic zone, it is essential to know exactly the shape and depth of the megasplay, and fine structures around the drilling site. Three important improvements were achieved in data processing before imaging. First, full deghosting and optimized zero phasing techniques could recover broadband signals, especially in low frequency, by compensating for ghost effects at both source and receiver, and removing source bubbles. Second, the multiple reflections better attenuated by applying advanced techniques in combination, and the strong noise caused by the Kuroshio were attenuated carefully. Third, data regularization by means of the optimized 4D trace interpolation was effective both to mitigate non-uniform fold distribution and to improve data quality. Further imaging processes led to obvious improvement from previous results by applying PSTM with higher order correction of VTI anisotropy, and PSDM based on the velocity model built by reflection tomography with TTI anisotropy. Final reflection images show new geological aspects, such as clear steep dip faults around the "notch", and fine scale faults related to main thrusts in frontal thrust zone. The improved images will highly contribute to understanding the deformation process in the old accretionary prism and seismogenic features related to the megasplay faults.

Three-dimensional model of the hydrostratigraphy and structure of the area in and around the U.S. Army-Camp Stanley Storage Activity Area, northern Bexar County, Texas

USGS Publications Warehouse

Pantea, Michael P.; Blome, Charles D.; Clark, Allan K.

2014-01-01

A three-dimensional model of the Camp Stanley Storage Activity area defines and illustrates the surface and subsurface hydrostratigraphic architecture of the military base and adjacent areas to the south and west using EarthVision software. The Camp Stanley model contains 11 hydrostratigraphic units in descending order: 1 model layer representing the Edwards aquifer; 1 model layer representing the upper Trinity aquifer; 6 model layers representing the informal hydrostratigraphic units that make up the upper part of the middle Trinity aquifer; and 3 model layers representing each, the Bexar, Cow Creek, and the top of the Hammett of the lower part of the middle Trinity aquifer. The Camp Stanley three-dimensional model includes 14 fault structures that generally trend northeast/southwest. The top of Hammett hydrostratigraphic unit was used to propagate and validate all fault structures and to confirm most of the drill-hole data. Differences between modeled and previously mapped surface geology reflect interpretation of fault relations at depth, fault relations to hydrostratigraphic contacts, and surface digital elevation model simplification to fit the scale of the model. In addition, changes based on recently obtained drill-hole data and field reconnaissance done during the construction of the model. The three-dimensional modeling process revealed previously undetected horst and graben structures in the northeastern and southern parts of the study area. This is atypical, as most faults in the area are en echelon that step down southeasterly to the Gulf Coast. The graben structures may increase the potential for controlling or altering local groundwater flow.

Spent Fuel Test-Climax: core logging for site investigation and instrumentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilder, D.G.; Yow, J.L. Jr.; Thorpe, R.K.

1982-05-28

As an integral part of the Spent Fuel Test-Climax 5150 ft (1570 m) of granite core was obtained. This core was diamond drilled in various sizes, mainly 38-mm and 76-mm diameters. The core was teken with single tube core barrels and was unoriented. Techniques used to drill and log this core are discussed, as well as techniques to orient the core. Of the 5150 ft (1570 m) of core more than 3645 ft (1111 m) was retained and logged in some detail. As a result of the core logging, geologic discontinuities were identified, joint frequency and spacing characterized. Discontinuities identifiedmore » included several joint sets, shear zones and faults. Correlations based on coring along were generally found to be impossible, even for the more prominent features. The only feature properly correlated from the exploratory drilling was the fault system at the end of the facility, but it was not identified from the exploratory core as a fault. Identification of discontinuities was later helped by underground mapping that identified several different joint sets with different characteristics. It was found that joint frequency varied from 0.3 to 1.1 joint per foot of core for open fractures and from 0.3 to 3.3/ft for closed or healed fractures. Histograms of fracture spacing indicate that there is likely a random distribution of spacing superimposed upon uniformly spaced fractures. It was found that a low angle joint set had a persistent mean orientation. These joints were healed and had pervasive wall rock alteration which made identification of joints in this set possible. The recognition of a joint set with known attitude allowed orientation of much of the core. This orientation technique was found to be effective. 10 references, 25 figures, 4 tables.« less

Helium isotopes in matrix pore fluids from SAFOD drill core samples suggest mantle fluids cannot be responsible for fault weakening

NASA Astrophysics Data System (ADS)

Ali, S.; Stute, M.; Torgersen, T.; Winckler, G.

2008-12-01

To quantify fluid flow in the San Andreas Fault (SAF) (and since direct fracture fluid sampling of the fault zone was not available), we have adapted a method to extract rare gases from matrix fluids of whole rocks by diffusion. Helium was measured on drill core samples obtained from 3054 m (Pacific Plate) to 3990 m (North American Plate) through the San Andreas Fault Zone (SAFZ) ~3300 m during SAFOD Phases I (2004), II (2005), III (2007). Samples were typically collected as 2.54 cm diameter subcores drilled into the ends of the cores, or from the core catcher and drillcore fragments within <2hr after core recovery. The samples were placed into ultra high vacuum stainless steel containers, flushed with ultra high purity nitrogen and immediately evacuated. Helium isotopes of the extracted matrix pore fluids and the solid matrix were determined by mass spectrometery at LDEO. Matrix porefluid 3He/4He ratios are ~0.4 - 0.5xRa (Ra: atmospheric 3He/4He = 1.384 x 10-6) in the Pacific Plate, increasing toward the SAFZ, while pore fluids in the North American Plate have a 3He/4He range of 0.7-0.9Ra, increasing away from the SAFZ (consistent with results from mud gas samples (Wiersberg and Erzinger, 2007) and direct fluid samples (Kennedy et al., 2007)). Helium isotope ratios of the solid matrix are less than 0.06Ra across the SAF in samples from both the North American and the Pacific plates, thereby excluding the host matrix as source for the enhanced isotopic signature. If the system is assumed to be in steady state, then the flux of mantle helium must be from the North American Plate to the Pacific plate. The steeper gradient in the Pacific Plate relative to the North American plate is consistent with a porosity corrected effective diffusivity. The source for this mantle helium in the North American Plate is likely related to a low crustal conductivity zone identified by magnetotelluric signals (Becken et al., 2008) that provides a channel for transport of mantle helium within brittle crust under high strain rates (Kennedy et al., 2007). The helium isotope gradients suggest that fault weakening by mantle-derived fluid pressure is unlikely. More likely, mantle fluids "bleed" into the North American plate below seismogenic depths and are transported across the fault by nonseismic, diffusive processes.

High Temperature 300°C Directional Drilling System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, Kamalesh; Aaron, Dick; Macpherson, John

2015-07-31

Many countries around the world, including the USA, have untapped geothermal energy potential. Enhanced Geothermal Systems (EGS) technology is needed to economically utilize this resource. Temperatures in some EGS reservoirs can exceed 300°C. To effectively utilize EGS resources, an array of injector and production wells must be accurately placed in the formation fracture network. This requires a high temperature directional drilling system. Most commercial services for directional drilling systems are rated for 175°C while geothermal wells require operation at much higher temperatures. Two U.S. Department of Energy (DOE) Geothermal Technologies Program (GTP) projects have been initiated to develop a 300°Cmore » capable directional drilling system, the first developing a drill bit, directional motor, and drilling fluid, and the second adding navigation and telemetry systems. This report is for the first project, “High Temperature 300°C Directional Drilling System, including drill bit, directional motor and drilling fluid, for enhanced geothermal systems,” award number DE-EE0002782. The drilling system consists of a drill bit, a directional motor, and drilling fluid. The DOE deliverables are three prototype drilling systems. We have developed three drilling motors; we have developed four roller-cone and five Kymera® bits; and finally, we have developed a 300°C stable drilling fluid, along with a lubricant additive for the metal-to-metal motor. Metal-to-metal directional motors require coatings to the rotor and stator for wear and corrosion resistance, and this coating research has been a significant part of the project. The drill bits performed well in the drill bit simulator test, and the complete drilling system has been tested drilling granite at Baker Hughes’ Experimental Test Facility in Oklahoma. The metal-to-metal motor was additionally subjected to a flow loop test in Baker Hughes’ Celle Technology Center in Germany, where it ran for more than 100 hours.« less

Subsurface Tectonics and Pingos of Northern Alaska

NASA Astrophysics Data System (ADS)

Skirvin, S.; Casavant, R.; Burr, D.

2008-12-01

We describe preliminary results of a two-phase study that investigated links between subsurface structural and stratigraphic controls, and distribution of hydrostatic pingos on the central coastal plain of Arctic Alaska. Our 2300 km2 study area is underlain by a complete petroleum system that supports gas, oil and water production from 3 of the largest oil fields in North America. In addition, gas hydrate deposits exist in this area within and just below the permafrost interval at depths of 600 to 1800 feet below sea level. Phase 1 of the study compared locations of subsurface faults and pingos for evidence of linkages between faulting and pingo genesis and distribution. Several hundred discrete fault features were digitized from published data and georeferenced in a GIS database. Fault types were determined by geometry and sense of slip derived from well log and seismic maps. More than 200 pingos and surface sediment type associated with their locations were digitized from regional surficial geology maps within an area that included wire line and seismic data coverage. Beneath the pingos lies an assemblage of high-angle normal and transtensional faults that trend NNE and NW; subsidiary trends are EW and NNW. Quaternary fault reactivation is evidenced by faults that displaced strata at depths exceeding 3000 meters below sea level and intersect near-surface units. Unpublished seismic images and cross-section analysis support this interpretation. Kinematics and distribution of reactivated faults are linked to polyphase deformational history of the region that includes Mesozoic rift events, succeeded by crustal shortening and uplift of the Brooks Range to the south, and differential subsidence and segmentation of a related foreland basin margin beneath the study area. Upward fluid migration, a normal process in basin formation and fault reactivation, may play yet unrecognized roles in the genesis (e.g. fluid charging) of pingos and groundwater hydrology. Preliminary analysis shows that more than half the pingos occur within 150 m of the vertical projections of subsurface fault plane traces. In a previous, unpublished geostatistical study, comparison of pingo and random locations indicated a non-random NE-trending alignment of pingos. This trend in particular matches the dominant orientation of fault sets that are linked to the most recent tectonic deformation of the region. A concurrent Phase 2 of the study examines the potential role of near-surface stratigraphic units in regard to both pingos and faults. Both surface and subsurface coarse-grained deposits across the region are often controlled by fault structures; this study is the first to assess any relationship between reservoir rocks and pingo locations. Cross-sections were constructed from well log data to depths of 100 meters. Subsurface elements were compared with surface features. Although some studies have linked fine-grained surface sediments with pingo occurrence, our analysis hints that coarse-grained sediments underlie pingos and may be related to near-surface fluid transmissivity, as suggested by other researchers. We also investigated pingo occurrence in relationship to upthrown or downthrown fault blocks that vary in the degree of deformation and fluid transmission. Results will guide a proposed pingo drilling project to test linkages between pingos, subsurface geology, hydrology, and petroleum systems. Findings from this study could aid research and planning for field exploration of similar settings on Earth and Mars.

Structure of the Suasselkä postglacial fault in northern Finland obtained by analysis of local events and ambient seismic noise

NASA Astrophysics Data System (ADS)

Afonin, Nikita; Kozlovskaya, Elena; Kukkonen, Ilmo; Dafne/Finland Working Group

2017-04-01

Understanding the inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of local seismic events and ambient seismic noise recorded by the temporary DAFNE array in the northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä postglacial fault (SPGF), which was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised an area of about 20 to 100 km and consisted of eight short-period and four broadband three-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September 2011-May 2013. Recordings of the array have being analysed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä gold mine. As a result, we found a number of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single-station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate corresponding surface wave dispersion curves. The S-wave velocity models were obtained as a result of dispersion curve inversion. The results suggest that the area of the SPGF corresponds to a narrow region of low S-wave velocities surrounded by rocks with high S-wave velocities. We interpret this low-velocity region as a non-healed mechanically weak fault damage zone (FDZ) formed due to the last major earthquake that occurred after the last glaciation.

Estimation of in-situ Stress Magnitudes and Orientations in a Deep South African Gold Mine: Applications to Fault Mechanics and Mine Safety

NASA Astrophysics Data System (ADS)

Lucier, A. M.; Heesakkers, V.; Zoback, M. D.; Reches, Z.

2006-12-01

As part of the Natural Earthquake Laboratory in South African Mines (NELSAM) project, we are investigating the far-field in-situ stress state around the TauTona gold mine. The far-field stress state is used as a boundary condition to quantify the stresses within the active mining area, and to evaluate the potential for reactivation of existing faults (or creation of new faults) in the NELSAM study area. Our main goals are to gain insight into earthquake processes under induced faulting conditions and to guide mining practices in improving underground seismic safety. To characterize in-situ stresses, we use an integrated stress measurement strategy that incorporates rock properties with breakout and drilling-induced tensile fracture observations from camera log images of several boreholes in the NELSAM study area at a depth of 3.5 km below the ground surface. The quantification of the far-field in-situ stress state is based on breakouts observed in a sub-horizontal borehole that extends 418 m away from the mined region and intersects the Pretorius fault, the largest fault-zone in the mine. The location, width and orientation of these breakouts were interpreted along the length of the borehole. Breakouts occur along most of the length of the borehole, with widths ranging from 25-95 deg and orientations fluctuating up to 45 deg around the sidewalls of the borehole. The fluctuations in breakout orientations are presumably due to slip on fault segments, and modeling these fluctuations provides constraints on the far-field stress state. Rock properties (uniaxial compressive strength, Young's modulus and Poisson's ratio) from on-going laboratory experiments will further constrain the stress magnitudes. The results of the stress characterization in this long borehole have been compared with independent stress determinations made in several 10-40 m long boreholes within the mined region to ensure consistency between the modeled far-field stress magnitudes and the observed near-field stresses. Our preliminary results indicate a normal faulting to normal/strike-slip stress state. Once a final stress model has been obtained, we will use it to assess the potential for fault reactivation and to predict future stress changes associated with further mining operations. The study was supported by NSF Continental Dynamics grant 0409605.

Microhole Test Data

DOE Data Explorer

Su, Jiann

2016-05-23

Drilling results from the microhole project at the Sandia High Operating Temperature test facility. The project is seeking to help reduce the cost of exploration and monitoring of geothermal wells and formations by drilling smaller holes. The tests were part of a control algorithm development to optimize the weight-on-bit (WOB) used during drilling with a percussive hammer.

Fort Bliss Geothermal Area Data: Temperature profile, logs, schematic model and cross section

DOE Data Explorer

Adam Brandt

2015-11-15

This dataset contains a variety of data about the Fort Bliss geothermal area, part of the southern portion of the Tularosa Basin, New Mexico. The dataset contains schematic models for the McGregor Geothermal System, a shallow temperature survey of the Fort Bliss geothermal area. The dataset also contains Century OH logs, a full temperature profile, and complete logs from well RMI 56-5, including resistivity and porosity data, drill logs with drill rate, depth, lithology, mineralogy, fractures, temperature, pit total, gases, and descriptions among other measurements as well as CDL, CNL, DIL, GR Caliper and Temperature files. A shallow (2 meter depth) temperature survey of the Fort Bliss geothermal area with 63 data points is also included. Two cross sections through the Fort Bliss area, also included, show well position and depth. The surface map included shows faults and well spatial distribution. Inferred and observed fault distributions from gravity surveys around the Fort Bliss geothermal area.

A reappraisal of the petroleum prospectivity of the Torquay Sub-basin, offshore southern Victoria, Australia

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, B.G.; Collins, G.

1996-01-01

The Torquay Sub-basin is located in the offshore part of the eastern Otway Basin, some 50km southwest of Melbourne. Three wells, all dry holes, were drilled between 1967 and 1992. Nerita-1 drilled in 1967 tested Eocene and Early Cretaceous reservoirs in a Miocene anticline. Snail-1 drilled in 1972 was not a valid structural test, and Wild Dog-1 drilled in 1992 tested Late Eocene sands in an Oligocene inversion faulted anticline sourced from Early Cretaceous coals. The area was assessed by previous explorers as lacking effective source. Work currently underway indicates these wells were dry because of lack of migration pathwaysmore » to the Tertiary. To the west, significant gas has been discovered in Late Cretaceous reservoirs offshore at Minerva-11 and LaBella-1, and onshore in wells in the Port Campbell Embayment. In the Bass Basin to the south, there have been consistent oil, condensate and gas shows. Geochemical analysis of the Early Cretaceous Eumeralla Formation and Casterton beds throughout the Otway Basin demonstrate they contain source rocks capable of generating both oil and gas. Our study indicates that early Cretaceous sandstones with porosities better than 20%, may be present at depths of less than 2000m in the Torquay Sub-basin in tilted fault blocks. Source would be from down-dip lacustrine shales of the Casterton Beds. The general basement high area in which this play is developed is some 15km by 15 km with up to 400m of relief.« less

A reappraisal of the petroleum prospectivity of the Torquay Sub-basin, offshore southern Victoria, Australia

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, B.G.; Collins, G.

1996-12-31

The Torquay Sub-basin is located in the offshore part of the eastern Otway Basin, some 50km southwest of Melbourne. Three wells, all dry holes, were drilled between 1967 and 1992. Nerita-1 drilled in 1967 tested Eocene and Early Cretaceous reservoirs in a Miocene anticline. Snail-1 drilled in 1972 was not a valid structural test, and Wild Dog-1 drilled in 1992 tested Late Eocene sands in an Oligocene inversion faulted anticline sourced from Early Cretaceous coals. The area was assessed by previous explorers as lacking effective source. Work currently underway indicates these wells were dry because of lack of migration pathwaysmore » to the Tertiary. To the west, significant gas has been discovered in Late Cretaceous reservoirs offshore at Minerva-11 and LaBella-1, and onshore in wells in the Port Campbell Embayment. In the Bass Basin to the south, there have been consistent oil, condensate and gas shows. Geochemical analysis of the Early Cretaceous Eumeralla Formation and Casterton beds throughout the Otway Basin demonstrate they contain source rocks capable of generating both oil and gas. Our study indicates that early Cretaceous sandstones with porosities better than 20%, may be present at depths of less than 2000m in the Torquay Sub-basin in tilted fault blocks. Source would be from down-dip lacustrine shales of the Casterton Beds. The general basement high area in which this play is developed is some 15km by 15 km with up to 400m of relief.« less

Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steve McRae; Thomas Walsh; Michael Dunn

2010-02-22

In November of 2008, the Department of Energy (DOE) and the North Slope Borough (NSB) committed funding to develop a drilling plan to test the presence of hydrates in the producing formation of at least one of the Barrow Gas Fields, and to develop a production surveillance plan to monitor the behavior of hydrates as dissociation occurs. This drilling and surveillance plan was supported by earlier studies in Phase 1 of the project, including hydrate stability zone modeling, material balance modeling, and full-field history-matched reservoir simulation, all of which support the presence of methane hydrate in association with the Barrowmore » Gas Fields. This Phase 2 of the project, conducted over the past twelve months focused on selecting an optimal location for a hydrate test well; design of a logistics, drilling, completion and testing plan; and estimating costs for the activities. As originally proposed, the project was anticipated to benefit from industry activity in northwest Alaska, with opportunities to share equipment, personnel, services and mobilization and demobilization costs with one of the then-active exploration operators. The activity level dropped off, and this benefit evaporated, although plans for drilling of development wells in the BGF's matured, offering significant synergies and cost savings over a remote stand-alone drilling project. An optimal well location was chosen at the East Barrow No.18 well pad, and a vertical pilot/monitoring well and horizontal production test/surveillance well were engineered for drilling from this location. Both wells were designed with Distributed Temperature Survey (DTS) apparatus for monitoring of the hydrate-free gas interface. Once project scope was developed, a procurement process was implemented to engage the necessary service and equipment providers, and finalize project cost estimates. Based on cost proposals from vendors, total project estimated cost is $17.88 million dollars, inclusive of design work, permitting, barging, ice road/pad construction, drilling, completion, tie-in, long-term production testing and surveillance, data analysis and technology transfer. The PRA project team and North Slope have recommended moving forward to the execution phase of this project.« less

Workshop to develop deep-life continental scientific drilling projects

DOE PAGES

Kieft, T. L.; Onstott, T. C.; Ahonen, L.; ...

2015-05-29

The International Continental Scientific Drilling Program (ICDP) has long espoused studies of deep subsurface life, and has targeted fundamental questions regarding subsurface life, including the following: "(1) What is the extent and diversity of deep microbial life and what are the factors limiting it? (2) What are the types of metabolism/carbon/energy sources and the rates of subsurface activity? (3) How is deep microbial life adapted to subsurface conditions? (4) How do subsurface microbial communities affect energy resources? And (5) how does the deep biosphere interact with the geosphere and atmosphere?" (Horsfield et al., 2014) Many ICDP-sponsored drilling projects have includedmore » a deep-life component; however, to date, not one project has been driven by deep-life goals, in part because geomicrobiologists have been slow to initiate deep biosphere-driven ICDP projects. Therefore, the Deep Carbon Observatory (DCO) recently partnered with the ICDP to sponsor a workshop with the specific aim of gathering potential proponents for deep-life-driven ICDP projects and ideas for candidate drilling sites. Twenty-two participants from nine countries proposed projects and sites that included compressional and extensional tectonic environments, evaporites, hydrocarbon-rich shales, flood basalts, Precambrian shield rocks, subglacial and subpermafrost environments, active volcano–tectonic systems, megafan deltas, and serpentinizing ultramafic environments. The criteria and requirements for successful ICDP applications were presented. Deep-life-specific technical requirements were discussed and it was concluded that, while these procedures require adequate planning, they are entirely compatible with the sampling needs of other disciplines. As a result of this workshop, one drilling workshop proposal on the Basin and Range Physiographic Province (BRPP) has been submitted to the ICDP, and several other drilling project proponents plan to submit proposals for ICDP-sponsored drilling workshops in 2016.« less

Spatial heterogeneity of stress and driving fluid pressure ratio inferred from mineral vein orientation along seismogenic megasplay fault (Nobeoka Thrust, Japan)

NASA Astrophysics Data System (ADS)

Otsubo, M.; Miyakawa, A.; Kawasaki, R.; Sato, K.; Yamaguchi, A.; Kimura, G.

2015-12-01

Fault zones including the damage zone and the fault core have a controlling influence on the crust's mechanical and fluid flow properties (e.g., Faulkner et al., 2010). In the Nankai subduction zone, southwest Japan, the velocity structures indicate the contrast of the pore fluid pressure between hanging wall and footwall of the megasplay fault (Tsuji et al., 2014). Nobeoka Thrust, which is an on-land example of an ancient megasplay fault, provides an excellent record of deformation and fluid flow at seismogenic depths (Kondo et al., 2005; Yamaguchi et al., 2011). Yamaguchi et al. (2011) showed that the microchemical features of syn-tectonic mineral veins along fault zones of the Nobeoka Thrust. The inversion approaches by using the mineral vein orientations can provide stress regimes and fluid driving pressure ratio (Jolly and Sanderson, 1997) at the time of fracture opening (e.g., Yamaji et al., 2010). In this study, we show (1) stress regimes in co- and post seismic period of the Nobeoka Thrust and (2) spatial heterogeneity of the fluid driving pressure ratio by using the mineral veins (extension veins) around the fault zone in the Nobeoka Thrust. We applied the inversion approach proposed by Sato et al. (2013) to estimate stress regimes by using the mineral vein orientations. The estimated stresses are the normal faulting stress regimes of which sigma 3 axes are almost horizontal and trend NNW-SSE in both the hanging wall and the footwall. The stress regimes are the negative stress for the reverse faulting stress regime that Kawasaki et al. (2014) estimated from the minor faults in the core samples of the Nobeoka Thrust Drilling Project (Hamahashi et al., 2013). And, the orientation of the sigma 3 axes of the estimated stress regime is parallel to the slip direction of the Nobeoka Thrust (Top to SSE; Kondo et al., 2005). These facts indicate the normal faulting stress regime at the time of fracture opening is the secondary stress generated by the slip of the Nobeoka Thrust. We estimated the fluid driving pressure ratio P* at the time of fracture opening by using the Mohr circle analysis that has been carried out using the vein orientation data. The estimated P* are 0.05 and 0.15-0.40 in the hanging wall and footwall, respectively. These results indicate that there are spatial differences of pore fluid pressure in the interseismic period.

Geologic Map and Cross Sections of the McGinness Hills Geothermal Area - GIS Data

DOE Data Explorer

Faulds, James E.

2013-12-31

Geologic map data in shapefile format that includes faults, unit contacts, unit polygons, attitudes of strata and faults, and surficial geothermal features. 5 cross‐sections in Adobe Illustrator format. Comprehensive catalogue of drill‐hole data in spreadsheet, shapefile, and Geosoft database formats. Includes XYZ locations of well heads, year drilled, type of well, operator, total depths, well path data (deviations), lithology logs, and temperature data. 3D model constructed with EarthVision using geologic map data, cross‐sections, drill‐hole data, and geophysics.

Earthquakes and depleted gas reservoirs: which comes first?

NASA Astrophysics Data System (ADS)

Mucciarelli, M.; Donda, F.; Valensise, G.

2015-10-01

While scientists are paying increasing attention to the seismicity potentially induced by hydrocarbon exploitation, so far, little is known about the reverse problem, i.e. the impact of active faulting and earthquakes on hydrocarbon reservoirs. The 20 and 29 May 2012 earthquakes in Emilia, northern Italy (Mw 6.1 and 6.0), raised concerns among the public for being possibly human-induced, but also shed light on the possible use of gas wells as a marker of the seismogenic potential of an active fold and thrust belt. We compared the location, depth and production history of 455 gas wells drilled along the Ferrara-Romagna arc, a large hydrocarbon reserve in the southeastern Po Plain (northern Italy), with the location of the inferred surface projection of the causative faults of the 2012 Emilia earthquakes and of two pre-instrumental damaging earthquakes. We found that these earthquake sources fall within a cluster of sterile wells, surrounded by productive wells at a few kilometres' distance. Since the geology of the productive and sterile areas is quite similar, we suggest that past earthquakes caused the loss of all natural gas from the potential reservoirs lying above their causative faults. To validate our hypothesis we performed two different statistical tests (binomial and Monte Carlo) on the relative distribution of productive and sterile wells, with respect to seismogenic faults. Our findings have important practical implications: (1) they may allow major seismogenic sources to be singled out within large active thrust systems; (2) they suggest that reservoirs hosted in smaller anticlines are more likely to be intact; and (3) they also suggest that in order to minimize the hazard of triggering significant earthquakes, all new gas storage facilities should use exploited reservoirs rather than sterile hydrocarbon traps or aquifers.

Fault geometry and cumulative offsets in the central Coast Ranges, California: Evidence for northward increasing slip along the San Gregorio-San Simeon-Hosgri fault

USGS Publications Warehouse

Langenheim, V.E.; Jachens, R.C.; Graymer, R.W.; Colgan, J.P.; Wentworth, C.M.; Stanley, R.G.

2012-01-01

Estimates of the dip, depth extent, and amount of cumulative displacement along the major faults in the central California Coast Ranges are controversial. We use detailed aeromagnetic data to estimate these parameters for the San Gregorio–San Simeon–Hosgri and other faults. The recently acquired aeromagnetic data provide an areally consistent data set that crosses the onshore-offshore transition without disruption, which is particularly important for the mostly offshore San Gregorio–San Simeon–Hosgri fault. Our modeling, constrained by exposed geology and in some cases, drill-hole and seismic-reflection data, indicates that the San Gregorio–San Simeon–Hosgri and Reliz-Rinconada faults dip steeply throughout the seismogenic crust. Deviations from steep dips may result from local fault interactions, transfer of slip between faults, or overprinting by transpression since the late Miocene. Given that such faults are consistent with predominantly strike-slip displacement, we correlate geophysical anomalies offset by these faults to estimate cumulative displacements. We find a northward increase in right-lateral displacement along the San Gregorio–San Simeon–Hosgri fault that is mimicked by Quaternary slip rates. Although overall slip rates have decreased over the lifetime of the fault, the pattern of slip has not changed. Northward increase in right-lateral displacement is balanced in part by slip added by faults, such as the Reliz-Rinconada, Oceanic–West Huasna, and (speculatively) Santa Ynez River faults to the east.

Microhole Coiled Tubing Bottom Hole Assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Don Macune

2008-06-30

The original objective of the project, to deliver an integrated 3 1/8-inch diameter Measurement While Drilling (MWD) and Logging While Drilling (LWD) system for drilling small boreholes using coiled tubing drilling, has been achieved. Two prototype systems have been assembled and tested in the lab. One of the systems has been successfully tested downhole in a conventional rotary drilling environment. Development of the 3 1/8-inch system has also lead to development and commercialization of a slightly larger 3.5-inch diameter system. We are presently filling customer orders for the 3.5-inch system while continuing with commercialization of the 3 1/8-inch system. Themore » equipment developed by this project will be offered for sale to multiple service providers around the world, enabling the more rapid expansion of both coiled tubing drilling and conventional small diameter drilling. The project was based on the reuse of existing technology whenever possible in order to minimize development costs, time, and risks. The project was begun initially by Ultima Labs, at the time a small company ({approx}12 employees) which had successfully developed a number of products for larger oil well service companies. In September, 2006, approximately 20 months after inception of the project, Ultima Labs was acquired by Sondex plc, a worldwide manufacturer of downhole instrumentation for cased hole and drilling applications. The acquisition provided access to proven technology for mud pulse telemetry, downhole directional and natural gamma ray measurements, and surface data acquisition and processing, as well as a global sales and support network. The acquisition accelerated commercialization through existing Sondex customers. Customer demand resulted in changes to the product specification to support hotter (150 C) and deeper drilling (20,000 psi pressure) than originally proposed. The Sondex acquisition resulted in some project delays as the resistivity collar was interfaced to a different MWD system and also as the mechanical design was revised for the new pressure requirements. However, the Sondex acquisition has resulted in a more robust system, secure funding for completion of the project, and more rapid commercialization.« less

SALTON SEA SCIENTIFIC DRILLING PROJECT: SCIENTIFIC PROGRAM.

USGS Publications Warehouse

Sass, J.H.; Elders, W.A.

1986-01-01

The Salton Sea Scientific Drilling Project, was spudded on 24 October 1985, and reached a total depth of 10,564 ft. (3. 2 km) on 17 March 1986. There followed a period of logging, a flow test, and downhole scientific measurements. The scientific goals were integrated smoothly with the engineering and economic objectives of the program and the ideal of 'science driving the drill' in continental scientific drilling projects was achieved in large measure. The principal scientific goals of the project were to study the physical and chemical processes involved in an active, magmatically driven hydrothermal system. To facilitate these studies, high priority was attached to four areas of sample and data collection, namely: (1) core and cuttings, (2) formation fluids, (3) geophysical logging, and (4) downhole physical measurements, particularly temperatures and pressures.

A continuous structural characterisation of Atlantis Massif using an integrated analysis of oriented downhole imagery and logging data

NASA Astrophysics Data System (ADS)

Pressling, Nicola; Morris, Antony; John, Barbara; MacLeod, Christopher

2010-05-01

Continuous wireline logging data are invaluable when less than 100% of drilled core material is recovered. The data provide information on missing units, record the true depth of features and uniquely constrain spatial orientation. Only by fully integrating continuous, oriented logging data and discrete, finer-scale core data can we develop a complete structural interpretation for drill holes that is not limited by sampling bias. Integrated Ocean Drilling Program (IODP) Expedition 304/305 sampled the Atlantis Massif oceanic core complex at the intersection between the Mid-Atlantic Ridge and the Atlantis Transform fault at 30°N. Hole U1309D penetrated 1415.5m into the central dome of the massif, which exposes the corrugated detachment fault surface denuding the lower crust and upper mantle. The recovered section is dominated by gabbro compositions that are complexly faulted and layered on a variety of scales, reflecting the complicated interplay between magmatic and tectonic processes controlling the formation, evolution and deformation of oceanic crust at slow-spreading ridges. The average core recovery at Atlantis Massif was 74%. Therefore, to augment and constrain structural interpretations based on limited core material, we used the Formation MicroScanner (FMS) wireline logging tool that measures microresistivity contrasts in the immediate vicinity of the borehole wall formation. The data are presented as an unwrapped image of the borehole cylinder, and inclined planar structural features that intersect the borehole, such as faults or veins, are shown as darker (more conductive) sinusoidal traces. The true dip and azimuth of these features can be calculated directly due to the inclusion of an accelerometer and magnetometer on the toolstring, which record the position and spatial orientation (with respect to magnetic north) of the tool within the borehole, respectively. 4324 distinct structural features have been identified in the FMS images between 97 and 1415mbsf (metres below sea floor). Distinctly different structural trends are seen across the five sub-units that are based on petrological and geochemical observations of the recovered core. In addition, variations in the borehole dimensions are used to define 115 zones of borehole breakout, with a cumulative extent of 434.76m (31% of the total drilled). Such regions often correspond to areas of poor recovery and are consequently poorly characterised using core samples. The extensive FMS-based structural database allows the variation in fracture networks and areas of weakness to be quantified at a high-resolution, leading to improved understanding of the hydrothermal fluid flow and melt pathways in the footwall section.

Structural Features of the Western Taiwan Foreland Basin in the Eastern Taiwan Strait since Late Miocene

NASA Astrophysics Data System (ADS)

WANG, J. H.; Liu, C. S.; Chang, J. H.; Yang, E. Y.

2017-12-01

The western Taiwan Foreland Basin lies on the eastern part of Taiwan Strait. The structures in this region are dominated by crustal stretch and a series of flexural normal faults have been developed since Late Miocene owing to the flexural of Eurasia Plate. Through deciphering multi-channel seismic data and drilling data, these flexural features are observed in the offshore Changhua coastal area. The flexure normal faults are important features to realize structural activity in the western Taiwan Foreland Basin. Yang et al. (2016) mention that the reactivated normal faults are found north of the Zhushuixi estuary. It should be a significant issue to decipher whether these faults are still active. In this study, we have analyzed all the available seismic reflections profiles in the central part of the Taiwan Strait, and have observed many pre-Pliocene normal faults that are mainly distributed in the middle of the Taiwan Strait to Changyun Rise, and we tentatively suggest that the formation of these faults may be associated with the formation of the foreland basal unconformity. Furthermore, we will map the distribution of these normal faults and examine whether the reactivated normal faults have extended to south of the Zhushuixi estuary. Finally, we discuss the relation between the reactivated normal faults in the Taiwan Strait and those faults onshore. Key words: Multichannel seismic reflection profile, Taiwan Strait, Foreland basin, normal fault.

Active Faults and Seismic Sources of the Middle East Region: Earthquake Model of the Middle East (EMME) Project

NASA Astrophysics Data System (ADS)

Gulen, L.; EMME WP2 Team*

2011-12-01

The Earthquake Model of the Middle East (EMME) Project is a regional project of the GEM (Global Earthquake Model) project (http://www.emme-gem.org/). The EMME project covers Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project consists of three main modules: hazard, risk, and socio-economic modules. The EMME project uses PSHA approach for earthquake hazard and the existing source models have been revised or modified by the incorporation of newly acquired data. The most distinguishing aspect of the EMME project from the previous ones is its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that permits continuous update, refinement, and analysis. An up-to-date earthquake catalog of the Middle East region has been prepared and declustered by the WP1 team. EMME WP2 team has prepared a digital active fault map of the Middle East region in ArcGIS format. We have constructed a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. The EMME project database includes information on the geometry and rates of movement of faults in a "Fault Section Database", which contains 36 entries for each fault section. The "Fault Section" concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far 6,991 Fault Sections have been defined and 83,402 km of faults are fully parameterized in the Middle East region. A separate "Paleo-Sites Database" includes information on the timing and amounts of fault displacement for major fault zones. A digital reference library, that includes the pdf files of relevant papers, reports and maps, is also prepared. A logic tree approach is utilized to encompass different interpretations for the areas where there is no consensus. Finally seismic source zones in the Middle East region have been delineated using all available data. *EMME Project WP2 Team: Levent Gülen, Murat Utkucu, M. Dinçer Köksal, Hilal Yalçin, Yigit Ince, Mine Demircioglu, Shota Adamia, Nino Sadradze, Aleksandre Gvencadze, Arkadi Karakhanyan, Mher Avanesyan, Tahir Mammadli, Gurban Yetirmishli, Arif Axundov, Khaled Hessami, M. Asif Khan, M. Sayab.

Initial Results from the New Stress Map of Texas Project

NASA Astrophysics Data System (ADS)

Lund Snee, J. E.; Zoback, M. D.

2015-12-01

Modern techniques for characterizing tectonic stress orientation and relative magnitude have been successfully used for more than 35 years. Nevertheless, large areas of North America lack high spatial resolution maps of stress orientation, magnitude, and faulting regime. In Texas, for example, <30 A-C-quality stress orientations are currently registered on the World Stress Map and only 7 of these points also describe the stress regime. Stress data are foundational elements of attempts to characterize tectonic driving forces, understand hazards associated with induced seismicity, and optimize production of oil, gas, and geothermal resources. This year, we launched the Texas Stress Map project to characterize tectonic stress patterns at higher spatial resolution across Texas and nearby areas. Following a successful effort just completed in Oklahoma, we will evaluate borehole breakouts, drilling-induced tensile fractures, shear wave anisotropy, and earthquake data. The principal data source will be FMI (fullbore formation microimager), UBI (ultrasonic borehole imager), cross-dipole sonic, density, and caliper logs provided by private industry. Earthquake moment tensor solutions from the U.S. Geological Survey, Saint Louis University and other sources will also be used. Our initial focus is on the Permian Basin and Barnett Shale petroleum plays due to the availability of data, but we will expand our analysis across the state as the project progresses. In addition, we hope to eventually apply the higher spatial resolution data coverage to understanding tectonic and geodynamic characteristics of the southwestern United States and northeastern Mexico. Here we present early results from our work to constrain stress orientations and faulting regime in and near Texas, and we also provide a roadmap for the ongoing research.

A Ship for Scientific Drilling.

ERIC Educational Resources Information Center

Peterson, M. N. A.; MacTernan, F. C.

1982-01-01

Traces the history and development of the Deep Sea Drilling Project, focusing on the Glomar Challenger, drilling improvements, and international significance. Includes photographs, illustrations, and tables. (DC)

The stress heat-flow paradox and thermal results from Cajon Pass

USGS Publications Warehouse

Lachenbruch, A.H.; Sass, J.H.

1988-01-01

Conventional friction models predict a substantial thermal anomaly associated with active traces of strike-slip faults, but no such anomaly is observed from over 100 heat-flow determinations along 1000 km of the San Andreas fault. The Cajon Pass well is being drilled to bring deep heat-flow and stress data to bear on this paradox. Preliminary stress results from Cajon Pass and a new interpretation of regional data by Mark D. Zoback and colleagues suggests that the maximum compressive stress near the fault is almost normal to the trace, and hence the resolved shear stress is low and the fault, weak. The heat-flow data show large variability with depth, probably from three-dimensional structure, and an overall decrease from over 90 mW/m2 in the upper kilometer to less than 80 mW/m2 in the lower 300 m with no evidence of advective heat transfer. -from Authors

Preliminary results of thermal conductivity and elastic wave velocity measurements of various rock samples collected from outcrops in hanging wall of the Alpine Fault

NASA Astrophysics Data System (ADS)

Lin, W.; Tadai, O.; Shigematsu, N.; Nishikawa, O.; Mori, H.; Townend, J.; Capova, L.; Saito, S.; Kinoshita, M.

2015-12-01

The Alpine Fault is a mature active fault zone likely to rupture in the near future and DFDP aims to measure physical and chemical conditions within the fault. DFDP-2B borehole was drilled into hanging wall of the Alpine Fault. Downhole temperature measurements carried out in DFDP-2B borehole showed that the geothermal gradient in the hanging wall of the fault is very high, likely reaching to 130-150 °C/km (Sutherland et al., 2015 AGU Fall Meeting). To explain this abnormal feature, the determination of thermal properties of all the rock types in the hanging wall of the Alpine Fault is essential. To measure thermal properties and elastic wave velocities, we collected six typical rock block samples from outcrops in Stony creek and Gaunt creek. These include ultramylonite, mylonite, muscovite schist, garnet amphibolite, protomylonite and schist, which are representative of the hanging wall of the Alpine Fault. Their wet bulk densities are 2.7 - 2.8 g/cm3, and porosities are 1.4 - 3.0%. We prepared a pair of 4 cm cube specimens of each rock type with one flat plane parallel to the foliation. First, we measured thermal conductivity by the transient plane heat source (hot disc) method in a bulk mode, i.e. to deal with the rock as an isotropic material. However, several samples have clearly visible foliation and are likely to be anisotropic. Thus, the data measured in bulk mode provided an average value of the rocks in the range of approximately 2.4 - 3.2 W/mK. The next step will be to measure thermal conductivity in an anisotropic mode. We also measured P wave velocity (Vp) using the same samples, but in two directions, i.e. parallel and perpendicular to the foliation, respectively. Our preliminary results suggested that Vp is anisotropic in all the six rocks. Generally, Vp parallel to foliation is higher than that in the perpendicular direction. Vp in the parallel direction ranged in 5.5 - 6.0 km/s, whereas in the perpendicular direction it was 4.4 - 5.5 km/s. We thank the PIs and onsite staffs of the DFDP-2 project for their helps to collecting rock samples, and the financial support by JSPS (Japan-New Zealand Joint Research Program).

Structural control on the Tohoku earthquake rupture process investigated by 3D FEM, tsunami and geodetic data

PubMed Central

Romano, F.; Trasatti, E.; Lorito, S.; Piromallo, C.; Piatanesi, A.; Ito, Y.; Zhao, D.; Hirata, K.; Lanucara, P.; Cocco, M.

2014-01-01

The 2011 Tohoku earthquake (Mw = 9.1) highlighted previously unobserved features for megathrust events, such as the large slip in a relatively limited area and the shallow rupture propagation. We use a Finite Element Model (FEM), taking into account the 3D geometrical and structural complexities up to the trench zone, and perform a joint inversion of tsunami and geodetic data to retrieve the earthquake slip distribution. We obtain a close spatial correlation between the main deep slip patch and the local seismic velocity anomalies, and large shallow slip extending also to the North coherently with a seismically observed low-frequency radiation. These observations suggest that the friction controlled the rupture, initially confining the deeper rupture and then driving its propagation up to the trench, where it spreads laterally. These findings are relevant to earthquake and tsunami hazard assessment because they may help to detect regions likely prone to rupture along the megathrust, and to constrain the probability of high slip near the trench. Our estimate of ~40 m slip value around the JFAST (Japan Trench Fast Drilling Project) drilling zone contributes to constrain the dynamic shear stress and friction coefficient of the fault obtained by temperature measurements to ~0.68 MPa and ~0.10, respectively. PMID:25005351

Structural control on the Tohoku earthquake rupture process investigated by 3D FEM, tsunami and geodetic data.

PubMed

Romano, F; Trasatti, E; Lorito, S; Piromallo, C; Piatanesi, A; Ito, Y; Zhao, D; Hirata, K; Lanucara, P; Cocco, M

2014-07-09

The 2011 Tohoku earthquake (Mw = 9.1) highlighted previously unobserved features for megathrust events, such as the large slip in a relatively limited area and the shallow rupture propagation. We use a Finite Element Model (FEM), taking into account the 3D geometrical and structural complexities up to the trench zone, and perform a joint inversion of tsunami and geodetic data to retrieve the earthquake slip distribution. We obtain a close spatial correlation between the main deep slip patch and the local seismic velocity anomalies, and large shallow slip extending also to the North coherently with a seismically observed low-frequency radiation. These observations suggest that the friction controlled the rupture, initially confining the deeper rupture and then driving its propagation up to the trench, where it spreads laterally. These findings are relevant to earthquake and tsunami hazard assessment because they may help to detect regions likely prone to rupture along the megathrust, and to constrain the probability of high slip near the trench. Our estimate of ~40 m slip value around the JFAST (Japan Trench Fast Drilling Project) drilling zone contributes to constrain the dynamic shear stress and friction coefficient of the fault obtained by temperature measurements to ~0.68 MPa and ~0.10, respectively.

UAV-based photogrammetry combination of the elevational outcrop and digital surface models: an example of Sanyi active fault in western Taiwan

NASA Astrophysics Data System (ADS)

Hsieh, Cheng-En; Huang, Wen-Jeng; Chang, Ping-Yu; Lo, Wei

2016-04-01

An unmanned aerial vehicle (UAV) with a digital camera is an efficient tool for geologists to investigate structure patterns in the field. By setting ground control points (GCPs), UAV-based photogrammetry provides high-quality and quantitative results such as a digital surface model (DSM) and orthomosaic and elevational images. We combine the elevational outcrop 3D model and a digital surface model together to analyze the structural characteristics of Sanyi active fault in Houli-Fengyuan area, western Taiwan. Furthermore, we collect resistivity survey profiles and drilling core data in the Fengyuan District in order to build the subsurface fault geometry. The ground sample distance (GSD) of an elevational outcrop 3D model is 3.64 cm/pixel in this study. Our preliminary result shows that 5 fault branches are distributed 500 meters wide on the elevational outcrop and the width of Sanyi fault zone is likely much great than this value. Together with our field observations, we propose a structural evolution model to demonstrate how the 5 fault branches developed. The resistivity survey profiles show that Holocene gravel was disturbed by the Sanyi fault in Fengyuan area.

Correlation of clayey gouge in a surface exposure of serpentinite in the San Andreas Fault with gouge from the San Andreas Fault Observatory at Depth (SAFOD)

NASA Astrophysics Data System (ADS)

Moore, Diane E.; Rymer, Michael J.

2012-05-01

Magnesium-rich clayey gouge similar to that comprising the two actively creeping strands of the San Andreas Fault in drill core from the San Andreas Fault Observatory at Depth (SAFOD) has been identified in a nearby outcrop of serpentinite within the fault zone at Nelson Creek. Each occurrence of the gouge consists of porphyroclasts of serpentinite and sedimentary rocks dispersed in a fine-grained, foliated matrix of Mg-rich smectitic clays. The clay minerals in all three gouges are interpreted to be the product of fluid-assisted, shear-enhanced reactions between quartzofeldspathic wall rocks and serpentinite that was tectonically entrained in the fault from a source in the Coast Range Ophiolite. We infer that the gouge at Nelson Creek connects to one or both of the gouge zones in the SAFOD core, and that similar gouge may occur at depths in between. The special significance of the outcrop is that it preserves the early stages of mineral reactions that are greatly advanced at depth, and it confirms the involvement of serpentinite and the Mg-rich phyllosilicate minerals that replace it in promoting creep along the central San Andreas Fault.

Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, B.L.; Gardner, M.C.; Koenig, J.B.

The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Westernmore » Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost circulation results in very high costs per foot drilled.« less

Coseismic fold scarp associated with historic earthquakes upon the Yoro active blind thrust, the Nobi-Ise fault zone, central Japan

NASA Astrophysics Data System (ADS)

Ishiyama, T.; Mueller, K.; Togo, M.

2004-12-01

We present structural models constrained by tectonic geomorphology, surface geologic mapping, shallow borehole transects and a high-resolution S-wave seismic reflection profile to define the kinematic evolution of a coseismic fold scarp along the Nobi-Ise fault zone (NIFZ). The NIFZ is an active intraplate fault system in central Japan, and consists of a 110-km-long array of active, east-verging reverse faults. Fold scarps along the Yoro fault are interpreted as produced during a large historic blind-thrust earthquake. The Yoro Mountains form the stripped core of the largest structure in the NIFZ and expose Triassic-Jurassic basement that are thrust eastward over a 2-km-thick sequence of Pliocene-Pleistocene strata deposited in the Nobi basin. This basement-cored fold is underlain by an active blind thrust that is expressed as late Holocene fold scarps along its eastern flank. Drilling investigations across the fold scarp at a site near Shizu identified at least three episodes of active folding associated with large earthquakes on the Yoro fault. Radiocarbon ages constrain the latest event as having occurred in a period that contains historical evidence for a large earthquake in A.D. 1586. A high resolution, S-wave seismic reflection profile at the same site shows that the topographic fold scarp coincides with the projected surface trace of the synclinal axis, across which the buried, early Holocene to historic sedimentary units are folded. This is interpreted to indicate that the structure accommodated coseismic fault-propagation folding during the A.D. 1586 blind thrust earthquake. Flexural-slip folding associated with secondary bedding-parallel thrusts may also deform late Holocene strata and act to consume slip on the primary blind thrust across the synclinal axial surfaces. The best-fitting trishear model for folded ca. 13 ka gravels deposited across the forelimb requires a 28\\deg east-dipping thrust fault. This solution suggests that a 4.2 mm/yr of slip rate has been accommodated on the Yoro fault during the late Holocene, with an average vertical rate of 1.9 mm/yr. This is consistent with longer-term slip rates calculated by a structural relief across a ca. 7.3 ka volcanic ash horizon (1.6 mm/yr), and ca. 110 ka innerbay clays (1.3 mm/yr) deposited across the forelimb. Our trishear model is thus able to account for the bulk of the folding history accommodated at shorter millennial timescales, suggesting that this technique may be used to adequately define slip rates on blind thrust faults.

Application of ERTS and EREP images to geologic investigations of the basin and range: Colorado plateau boundary in northwestern and north-central Arizona

NASA Technical Reports Server (NTRS)

Goetz, A. F. H. (Principal Investigator); Billingsley, F. C.; Elston, D. P.; Lucchita, I.; Shoemaker, E. M.

1974-01-01

The author has identified the following significant results. In the course of the ERTS investigation in the Cataract Creek Basin of the Coconino Plateau it was recognized that shallow perched ground water associated with the Kaibab Limestone could be discovered by means of drilling guided by geologic mapping aided by the use of ERTS imagery. At the Globe Ranch, the perched water table is only 5 meters beneath the surface at the site of the original, hand dug well. Recharge occurs from local runoff and from direct precipitation on the outcrop belt of the sandstone. This well provides water for the ranch at the rate of about 1,000 gallons a week. In order to explore the possibility of further developing this aquifer, unit 5 was mapped over an area of about 50 square miles in the vicinity of the hand-dug well, with negative results. A new location was then picked for drilling based on the occurrence of unit 5 in a favorable structural setting. This location was along a normal fault, and it was anticipated that water might be structurally trapped within the down-dropped block of the fault. Four shallow testholes were drilled and all encountered water. These four water-bearing holes are currently being monitored and will be tested to determine potential production of water from the local sandstone aquifer.

Class III Mid-Term Project, "Increasing Heavy Oil Reserves in the Wilmington Oil Field Through Advanced Reservoir Characterization and Thermal Production Technologies"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott Hara

2007-03-31

The overall objective of this project was to increase heavy oil reserves in slope and basin clastic (SBC) reservoirs through the application of advanced reservoir characterization and thermal production technologies. The project involved improving thermal recovery techniques in the Tar Zone of Fault Blocks II-A and V (Tar II-A and Tar V) of the Wilmington Field in Los Angeles County, near Long Beach, California. A primary objective has been to transfer technology that can be applied in other heavy oil formations of the Wilmington Field and other SBC reservoirs, including those under waterflood. The first budget period addressed several producibilitymore » problems in the Tar II-A and Tar V thermal recovery operations that are common in SBC reservoirs. A few of the advanced technologies developed include a three-dimensional (3-D) deterministic geologic model, a 3-D deterministic thermal reservoir simulation model to aid in reservoir management and subsequent post-steamflood development work, and a detailed study on the geochemical interactions between the steam and the formation rocks and fluids. State of the art operational work included drilling and performing a pilot steam injection and production project via four new horizontal wells (2 producers and 2 injectors), implementing a hot water alternating steam (WAS) drive pilot in the existing steamflood area to improve thermal efficiency, installing a 2400-foot insulated, subsurface harbor channel crossing to supply steam to an island location, testing a novel alkaline steam completion technique to control well sanding problems, and starting on an advanced reservoir management system through computer-aided access to production and geologic data to integrate reservoir characterization, engineering, monitoring, and evaluation. The second budget period phase (BP2) continued to implement state-of-the-art operational work to optimize thermal recovery processes, improve well drilling and completion practices, and evaluate the geomechanical characteristics of the producing formations. The objectives were to further improve reservoir characterization of the heterogeneous turbidite sands, test the proficiency of the three-dimensional geologic and thermal reservoir simulation models, identify the high permeability thief zones to reduce water breakthrough and cycling, and analyze the nonuniform distribution of the remaining oil in place. This work resulted in the redevelopment of the Tar II-A and Tar V post-steamflood projects by drilling several new wells and converting idle wells to improve injection sweep efficiency and more effectively drain the remaining oil reserves. Reservoir management work included reducing water cuts, maintaining or increasing oil production, and evaluating and minimizing further thermal-related formation compaction. The BP2 project utilized all the tools and knowledge gained throughout the DOE project to maximize recovery of the oil in place.« less

Astrobiology Drilling Program of the NASA Astrobiology Institute

NASA Astrophysics Data System (ADS)

Runnegar, B.

2004-12-01

Access to unweathered and uncontaminated samples of the least altered, oldest, sedimentary rocks is essential for understanding the early history of life on Earth and the environments in which it may have existed. For this reason, the NASA Astrobiology Institute (NAI) has embarked on two international programs, a series of Field Workshops aimed at making the most important surface samples available to investigators, and the Astrobiology Drilling Program (ADP), which serves to provide access to fresh subsurface samples when the scientific objectives require them. The Astrobiology Drilling Program commenced in Western Australia in 2003 with the initiation of its first project, the Archean Biosphere Drilling Project (ABDP). Funding for the ABDP came mainly from the Japanese Government through Kagoshima University and from NASA through the NAI Team at Pennsylvania State University, but significant technical and logistic support was provided by the Geological of Western Australia and, to a lesser extent, by the University of Western Australia. Six diamond drill cores totalling 1.4 km were obtained from astrobiologically important successions in the 3.3-3.5 Ga-old Pilbara Craton of northern Western Australia. Drilling in 2004 also occurred in Western Australia. The Deep Time Drilling Project (DTDP), a spin-off from the NAI's Mission to Early Earth Focus Group, completed one long hole, aimed mainly at fossil biomolecules (biomarkers) and other geochemical indicators of early life. The DTDP and the ABDP also jointly drilled two other important holes 2004, one through the oldest known erosion surface (and possible soil profile). The other intersected well-preserved middle Archean sediments. These efforts parallel other drilling initiatives within the wider astrobiological community that are taking place in Western Australia, South Africa, Spain, and arctic Canada. The ADP is managed by the NAI through a Steering Committee appointed by the NAI Director. Samples of cores obtained through ADP projects are available to the whole community, following a one year embargo, upon application to project PIs and the ADP Steering Committee.

Real-Time Fluid and Gas Monitoring During Drilling of the SAFOD Main Hole in Parkfield, CA.

NASA Astrophysics Data System (ADS)

Wiersberg, T.; Erzinger, J.

2005-12-01

Little is known about the role and origin of fluids and gases associated with the San Andreas Fault zone (SAF). To gain information on fluids and gases at depth, we performed real-time mud gas monitoring during drilling of the SAFOD (San Andreas Fault Observatory at Depth) Pilot Hole (PH) and Main Hole (MH). Gas extracted from returning drill mud was piped into a nearby laboratory trailer and analyzed on-line. Permanent gases were detected using a portable mass spectrometer, hydrocarbons with a gas chromatograph, and the 222Rn-activity with a Lucas-Cell detector. When significant amounts of non-atmospheric gases were detected, off-line gas samples were collected from the gas line for further isotope studies. The SAFOD PH and MH were drilled in only a few meter distance, but in contrast to the straight PH, which penetrates through 768 m of sediments into granites down to 2168 m target depth (TD), the nearby MH is deviated towards the SAF and returns into sedimentary strata below 1930 m. The MH drilled sedimentary rocks down to 3987 m TD, approximately 45 m northeast of the surface trace of the SAF. From surface to 1930 m, the depth distribution of gas is similar for SAFOD PH and MH. Shear zones, identified by geophysical logging, are often characterized by elevated concentrations of CH4, CO2, H2, Rn, and He. The same gases were found in the MH below 1930 m, but their concentrations were, with the exception of He, significantly higher: CH4, CO2, and H2 sometimes reach several volume percent. Generally, the gas composition is partly controlled by the lithology. Variation in the methane concentration in several depth intervals reflects the changes in lithology from low gas abundance in clays and silts to more gas rich shales, which are the source rocks for hydrocarbons. Highly porous and permeable sandstone yield the highest concentrations of hydrocarbons (up to 15 vol% methane), and may be regarded as reservoir rocks. We interpret high radon activities in mud gas as indicator for circulating fluids entering the borehole via fractures. These fluids are also rich in hydrocarbons, carbon dioxide, and hydrogen, but only low concentrated in helium. Such intervals could be identified in several depth intervals (2675-2750 m, 2825-2900 m, and 3550-3650 m depth, and below 3700 m). The hydrocarbons in the surrounding rocks show a similar composition as those associated with fault zones. In addition to the low helium concentration, these results demonstrate fluid migration from the nearby with only little evidence for gas migration from a deeper source. A striking observation is the high amount of hydrogen found in these intervals. We can exclude a significant contribution of artificial hydrogen (drilling artifact) and mantle hydrogen. From soil gas studies, it is known that fault zones sometimes show enhanced concentration of hydrogen. As a possible source of hydrogen, the interaction of water with freshly ground rock, caused by fault zone movement, is discussed. Isotopic studies on hydrogen in combination with laboratory experiments are ongoing to test hydrogen synthesis by rock-water interaction. First isotopic studies on δ13C of methane indicate mixing of microbial methane with only small amounts of methane generated by thermal degradation of organic matter in the shallower depth (down to ~2500 m). Below this depth, the concentration of heavy hydrocarbons increases. CH4/(C2H6+C3H8) significantly drops from >100 to values <30 towards the bottom of the MH, and, methane becomes isotopically heavier, which is more typical for thermogenic hydrocarbons.

Earthquake Model of the Middle East (EMME) Project: Active Fault Database for the Middle East Region

NASA Astrophysics Data System (ADS)

Gülen, L.; Wp2 Team

2010-12-01

The Earthquake Model of the Middle East (EMME) Project is a regional project of the umbrella GEM (Global Earthquake Model) project (http://www.emme-gem.org/). EMME project region includes Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project will use PSHA approach and the existing source models will be revised or modified by the incorporation of newly acquired data. More importantly the most distinguishing aspect of the EMME project from the previous ones will be its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that will permit continuous update, refinement, and analysis. A digital active fault map of the Middle East region is under construction in ArcGIS format. We are developing a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. Similar to the WGCEP-2007 and UCERF-2 projects, the EMME project database includes information on the geometry and rates of movement of faults in a “Fault Section Database”. The “Fault Section” concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far over 3,000 Fault Sections have been defined and parameterized for the Middle East region. A separate “Paleo-Sites Database” includes information on the timing and amounts of fault displacement for major fault zones. A digital reference library that includes the pdf files of the relevant papers, reports is also being prepared. Another task of the WP-2 of the EMME project is to prepare a strain and slip rate map of the Middle East region by basically compiling already published data. The third task is to calculate b-values, Mmax and determine the activity rates. New data and evidences will be interpreted to revise or modify the existing source models. A logic tree approach will be utilized for the areas where there is no consensus to encompass different interpretations. Finally seismic source zones in the Middle East region will be delineated using all available data. EMME Project WP2 Team: Levent Gülen, Murat Utkucu, M. Dinçer Köksal, Hilal Domaç, Yigit Ince, Mine Demircioglu, Shota Adamia, Nino Sandradze, Aleksandre Gvencadze, Arkadi Karakhanyan, Mher Avanesyan, Tahir Mammadli, Gurban Yetirmishli, Arif Axundov, Khaled Hessami, M. Asif Khan, M. Sayab.

Acoustic stratigraphy of Bear Lake, Utah-Idaho: late Quaternary sedimentation patterns in a simple half-graben

USGS Publications Warehouse

Colman, Steven M.

2006-01-01

A 277-km network of high-resolution seismic-reflection profiles, supplemented with a sidescan-sonar mosaic of the lake floor, was collected in Bear Lake, Utah–Idaho, in order to explore the sedimentary framework of the lake's paleoclimate record. The acoustic stratigraphy is tied to a 120 m deep, continuously cored drill hole in the lake. Based on the age model for the drill core, the oldest continuously mapped acoustic reflector in the data set has an age of about 100 ka, although older sediments were locally imaged. The acoustic stratigraphy of the sediments below the lake indicates that the basin developed primarily as a simple half-graben, with a steep normal-fault margin on the east and a flexural margin on the west. As expected for a basin controlled by a listric master fault, seismic reflections steepen and diverge toward the fault, bounding eastward-thickening sediment wedges. Secondary normal faults west of the master fault were imaged beneath the lake and many of these faults show progressively increasing offset with depth and age. Several faults cut the youngest sediments in the lake as well as the modern lake floor. The relative simplicity of the sedimentary sequence is interrupted in the northwestern part of the basin by a unit that is interpreted as a large (4 × 10 km) paleodelta of the Bear River. The delta overlies a horizon with an age of about 97 ka, outcrops at the lake floor and is onlapped by much of the uppermost sequence of lake sediments. A feature interpreted as a wave-cut bench occurs in many places on the western side of the lake. The base of this bench occurs at a depth (22–24 m) similar to that (20–25 m) of the distal surface of the paleodelta. Pinch-outs of sedimentary units are common in relatively shallow water on the gentle western margin of the basin and little Holocene sediment has accumulated in water depths of less than 30 m. On the steep eastern margin of the basin, sediments commonly onlap the hanging wall of the East Bear Lake Fault. However, no major erosional or depositional features suggestive of shoreline processes were observed on acoustic profiles in water deeper than about 20–25 m.

Textures of water-rich mud sediments from the continental margin offshore Costa Rica (IODP expeditions 334 and 344)

NASA Astrophysics Data System (ADS)

Kuehn, Rebecca; Stipp, Michael; Leiss, Bernd

2017-04-01

During sedimentation and burial at continental margins, clay-rich sediments develop crystallographic preferred orientations (textures) depending on the ongoing compaction as well as size distribution and shape fabrics of the grains. Such textures can control the deformational properties of these sediments and hence the strain distribution in active continental margins and also the frictional behavior along and around the plate boundary. Strain-hardening and discontinuous deformation may lead to earthquake nucleation at or below the updip limit of the seismogenic zone. We want to investigate the active continental margin offshore Costa Rica where the oceanic Cocos plate is subducted below the Caribbean plate at a rate of approximately 9 cm per year. The Costa Rica trench is well-known for shallow seismogenesis and tsunami generation. As it is an erosive continental margin, both the incoming sediments from the Nazca plate as well as the slope sediments of the continental margin can be important for earthquake nucleation and faulting causing sea-floor breakage. To investigate texture and composition of the sediments and hence their deformational properties we collected samples from varying depth of 7 different drilling locations across the trench retrieved during IODP expeditions 334 and 344 as part of the Costa Rica Seismogenesis Project (CRISP). Texture analysis was carried out by means of synchrotron diffraction, as only this method is suitable for water-bearing samples. As knowledge on the sediment composition is required as input parameter for the texture data analysis, additional X-ray powder diffraction analysis on the sample material has been carried out. Samples for texture measurements were prepared from the original drill cores using an internally developed cutter which allows to produce cylindrical samples with a diameter of about 1.5 cm. The samples are oriented with respect to the drill core axis. Synchrotron texture measurements were conducted at the ESRF (European Synchrotron Radiation Facility) in Grenoble and the DESY (German Electron Synchrotron) in Hamburg. Samples were measured in transmission mode perpendicular to their cylinder axis with a beam diameter of 500 µm. Measurements were taken from 0 to 175° in 5° steps resulting in 36 images from a 2D image plate detector. Measurement time was in a range from 1 to 3 seconds. Due to the different, low symmetric mineral phases a large number of mostly overlapping reflections results. Such data can only be analyzed by the Rietveld method, in our case implemented in the software package MAUD (Materials Analysis Using Diffraction). Preliminary results show distinct textures depending on the composition and the origin of the samples, i.e. on drilling location and depth, which may be critical for strain localization and faulting of these samples. The results are also important for the analysis of experimentally deformed samples from the same drill cores which showed structurally weak and structurally strong deformation behavior during triaxial compression.

DOE Office of Scientific and Technical Information (OSTI.GOV)

William C. Maurer; William J. McDonald; Thomas E. Williams

Underbalanced drilling is experiencing growth at a rate that rivals that of horizontal drilling in the mid-1980s and coiled-tubing drilling in the 1990s. Problems remain, however, for applying underbalanced drilling in a wider range of geological settings and drilling environments. This report addresses developments under this DOE project to develop products aimed at overcoming these problems. During Phase I of the DOE project, market analyses showed that up to 12,000 wells per year (i.e., 30% of all wells) will be drilled underbalanced in the U.S.A. within the next ten years. A user-friendly foam fluid hydraulics model (FOAM) was developed formore » a PC Windows environment during Phase I. FOAM predicts circulating pressures and flow characteristics of foam fluids used in underbalanced drilling operations. FOAM is based on the best available mathematical models, and was validated through comparison to existing models, laboratory test data and field data. This model does not handle two-phase flow or air and mist drilling where the foam quality is above 0.97. This FOAM model was greatly expanded during Phase II including adding an improved foam rheological model and a ''matching'' feature that allows the model to be field calibrated. During Phase I, a lightweight drilling fluid was developed that uses hollow glass spheres (HGS) to reduce the density of the mud to less than that of water. HGS fluids have several advantages over aerated fluids, including they are incompressible, they reduce corrosion and vibration problems, they allow the use of mud-pulse MWD tools, and they eliminate high compressor and nitrogen costs. Phase II tests showed that HGS significantly reduce formation damage with water-based drilling and completion fluids and thereby potentially can increase oil and gas production in wells drilled with water-based fluids. Extensive rheological testing was conducted with HGS drilling and completion fluids during Phase II. These tests showed that the HGS fluids act similarly to conventional fluids and that they have potential application in many areas, including underbalanced drilling, completions, and riserless drilling. Early field tests under this project are encouraging. These led to limited tests by industry (which are also described). Further field tests and cost analyses are needed to demonstrate the viability of HGS fluids in different applications. Once their effectiveness is demonstrated, they should find widespread application and should significantly reduce drilling costs and increase oil and gas production rates. A number of important oilfield applications for HGS outside of Underbalanced Drilling were identified. One of these--Dual Gradient Drilling (DGD) for deepwater exploration and development--is very promising. Investigative work on DGD under the project is reported, along with definition of a large joint-industry project resulting from the work. Other innovative products/applications are highlighted in the report including the use of HGS as a cement additive.« less

Bedrock Geology of the DFDP-2 Drill-Site

NASA Astrophysics Data System (ADS)

Toy, V.; Sutherland, R.; Townend, J.

2015-12-01

Bedrock was encountered in DFDP-2B at drilled depths (MD) of 238.50-893.18 m (vertical depths of 238.40-818.00 m). Continuous sampling of cuttings revealed the bedrock is composed predominantly of ductilely sheared mylonite-series lithologies exhumed from the roots of the Alpine Fault zone. The protolith is interpreted to be amphibolite facies metasediments classified as part of the Aspiring Subdivision of the Torlesse Supergroup. Onsite description of whole cuttings and thin sections made within a few hours of sample recovery allowed identification of progressive structural changes. Fabrics were schistose in the upper part of the hole, but at greater depths we observed increasing indications that the rocks had been subjected to simple shear deformation. These macro-and micro-structural features are consistent with those that typify the Alpine Fault mylonite sequence previously described, and were used as input to drilling decisions. The structural features found to be the most useful indicators of ductile simple shear strain accommodated by the recovered rocks were the occurrence of shear bands; changes in mean quartz grain size; changes in maximum mica grain size; and redistribution of or changes in microstructural setting of accessory phases (e.g. graphite). The quartz:mica ratio based on mass was also determined but the extent to which this reflects true lithologic variations is unclear, as washing and winnowing of the samples (both by circulating drill fluids and during the sample collection process) probably modified bulk mineralogy in different particle size domains. Nevertheless, the quartz:mica dataset suggests a dramatic change in mineralogy at 730 m MD (vertical depth of 695 m). This coincides with a pronounced step in the temperature gradient, possibly related to large changes in hydrogeology.

In situ stress and pore pressure in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Flemings, P. B.; Boutt, D.; Doan, M.-L.; Ito, T.; McNeill, L.; Byrne, T.; Conin, M.; Lin, W.; Kano, Y.; Araki, E.; Eguchi, N.; Toczko, S.

2013-05-01

situ stress and pore pressure are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, pore pressure, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ pore pressure and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10-17 to 4.23 × 10-14 m2. Pore fluid pressures are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009.

Collisional Orogeny in the Scandinavian Caledonides (COSC): Scientific objectives for the planned 2.5 km deep COSC-2 borehole

NASA Astrophysics Data System (ADS)

Juhlin, Christopher; Anderson, Mark; Dopson, Mark; Lorenz, Henning; Pascal, Christophe; Piazolo, Sandra; Roberts, Nick; Rosberg, Jan-Erik; Tsang, Chin-Fu

2016-04-01

The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific drilling project employs two fully cored boreholes for investigating mountain building processes at mid-crustal levels in a deeply eroded Paleozoic collisional orogen of Alpine-Himalayan size. The two COSC boreholes will provide a unique c. 5 km deep composite section from a hot allochthon through the underlying 'colder' nappes, the main décollement and into the basement of the collisional underriding plate. COSC's unprecedented wealth of geophysical field and borehole data combined with the petrology, geochronology and rock physics information obtained from the drill cores will develop into an integrated model for a major collisional mountain belt. This can be utilized as an analogue to better understand similar modern tectonic settings (Himalaya, Izu-Bonin-Mariana, amongst others) and, thus, advance our understanding of such complex systems and how they affect the (human) environment. COSC investigations and drilling activities are focused in the Åre-Mörsil area (Sweden) of central Scandinavia. The first drill hole, COSC-1, was completed in late August 2014 with near 100% core recovery down to 2.5 km. It targeted the high-grade metamorphic Seve Nappe Complex (SNC) and its contact with the underlying allochthon, investigating how this metasedimentary unit, that was initially deeply subducted during orogeny, was exhumed and then, still hot, emplaced as an allochthon onto the foreland of the underriding plate. COSC-2 will investigate the main Caledonian décollement, which is the major detachment that separates the Caledonian allochthons from the autochthonous basement of the Fennoscandian Shield, and the character of the deformation in the basement. Combined seismic, magnetotelluric (MT) and magnetic data provide control on the basement structure and the depth to the main décollement, believed to be hosted in the carbon-rich highly conductive Alum Shale. Key targets are to understand the geometry, stress distribution and rheology of the main décollement and associated fault systems in the foreland of one of the Earth's largest orogens, and to determine the relationship between the basement deformation and the thrust tectonics in the nappes above. COSC-2 will provide insights into the evolution of Baltica near the Ordovician-Silurian boundary by providing a new, distal section from the Early Paleozoic sedimentary basin. High-quality, high-resolution temperature profiles will allow the reconstruction of the ground surface temperature history and its variations for up to 100000 years and gather new knowledge about the Weichselian glaciation and climate evolution in northern Europe during the Holocene, including industrial age trends. Furthermore, research will address the hydrogeological and geothermic characteristics of the mountain belt and investigate the geological energy sources utilized by the deep biosphere. The drilling program and on-site science will build on the experience from drilling COSC-1. Applications for drilling related costs have been made to ICDP and the Swedish Research Council and if funded, drilling can be performed in 2017 at the earliest. Researchers interested in any aspect of the COSC project are invited to join and provide parallel funding for drilling, on-site science, and studies on core and downhole geophysics.

Issues and Concerns in Robotic Drilling

NASA Technical Reports Server (NTRS)

Glass, Brian

2003-01-01

Exploration of the Martian subsurface will be essential in the search for life and water, given the desiccated and highly oxidized conditions on the surface. Discovery of these, at least in non-fossil form, is unlikely without drilling or other physical access to the subsurface. Hence subsurface access will be critical for both future in-situ science and Mars sample return. Drilling applications present many new challenges for diagnosis and control technology. Traditionally, diagnosis has concentrated on determining the internal state of a system, and detecting failures of system components. In the case of drilling applications, an additional challenge is to diagnose the interactions between the drill and its environment. This is necessary because particular observations of the drilling operation may be consistent with a number of possible problems, including faults in the equipment, but also changes in the material being drilled (for example, from rock to ice). The diagnosis of a particular observation may also depend on knowledge of geological formations previously encountered during drilling, and different remedial actions may be required for each diagnosis. Current 2009 Mars mission scenarios call for no more than 33 sols to be spent drilling. Yet they also call for a baseline of two 2m-deep holes in each of three target areas, for a total of six drilling operations. Using current levels of automation, it is estimated that 15-16 sols would be required to drill each hole. As a result of this, either the drilling part of the mission plan will need to be severely downscoped to no more than two holes total, or on-board automation and robotics must be increased in order to reduce the number of sols required per hole by removing ground control from the drilling control loop. This lecture will discuss salient issues and concerns of robotic drilling automation compares with other applications, and implementation constraints.

Tectonic structure and petroleum potential of TayabasBay southeast Luzon, Philippines

NASA Astrophysics Data System (ADS)

Bacud, Jaime; Moore, Aidan; Lee, Chao-Skiing

Tayabas Bay is one of four offshore Philippine areas where the Australian GeologicalSurvey Organization and the Philippine Department of Energy conducted a cooperative marine seismic, gravity, magnetic, bathymetry and geochemical survey. The project acquired new seismic data and reprocessed the 1983 World Bank seismic sections which were all integrated with previous oil company data. the absence of wells drilled offshore, interpretation of offshore seismic data was complemented by onshore well log information and stratigraphy of the Bondoc Peninsula. Geochemistry data, both offshore and onshore, were analyzed to confirm the presence of mature source rocks and hydrocarbon migration. A new seismic interpretation has revealed the structure of this tectonically active geologically complex area. A major structural feature interpreted in offshore Tayabas Bay was a N-NW-trending strike-slip fault which is believed to be a northern splay of the Sibuyan Sea Fault. The authors named this fault the Tayabas Bay Fault and due to its association with the Philippine Fault System the movement is assumed to be left-lateral. The present study suggested the presence of a prolific source rock in the Middle Miocene Vigo Formation and/or the Late Oligocene to Early Miocene Panaon Limestone. Oil and gas generation have been and are occurring in the Bondoc Sub-basin. Two groups of reservoirs were identified, the shelf carbonates beneath the Middle Miocene shales on the Marinduque Platform and the early Middle Miocene carbonates and basin-floor clastics near the base of the Vigo Formation. Carbonate reservoirs are believed to be present in traps formed when the Late Oligocene to Early Miocene carbonate reefs and shelf deposits of the Panaon Limestone were buried by the Middle Miocene shales. A later set of traps was formed and possibly superimposed by the intense deformation associated with the Philippine Fault System which has continued from the Late Pliocene up to the present. Evaluation for hydrocarbon reserves of several possible traps identified three significant leads, namely the Yuni Lead in the south, the Mulanay in the central area and the Mabio in the North.

Massive sulfide exploration models of the Iberian Pyrite Belt Neves Corvo mine region, based in a 3D geological, geophysical and geochemical ProMine study

NASA Astrophysics Data System (ADS)

Inverno, Carlos; Matos, João Xavier; Rosa, Carlos; Mário Castelo-Branco, José; Granado, Isabel; Carvalho, João; João Baptista, Maria; Represas, Patrícia; Pereira, Zélia; Oliveira, Tomás; Araujo, Vitor

2013-04-01

The Iberian Pyrite Belt (IPB) hosts one of the largest concentrations of massive sulfides in the Earth's crust. This highly productive VMS belt contains more than 85 massive sulfide deposits, totalling an estimate of 1600 Mt of massive ore and about 250 Mt of stockwork ore (Leistel et al., 1998; Oliveira et al., 2005; Tornos, 2006). Included in the South Portuguese Zone the IPB is represented by the Phyllite-Quartzite Group (PQG) composed of shales and quartzites of late Devonian age followed by the Volcanic-Sedimentary Complex (VSC) a submarine succession of sediments and felsic and basic volcanic rocks (late Famennian-late Viséan age). Above the IPB a turbidite sedimentary unit occurs being represented by the Baixo Alentejo Flysch Group (BAFG). The ore deposits are hosted by felsic volcanic rocks and sediments that are dominant in the lower part of the VSC succession. The Neves Corvo (ProMine, EU FP7) project area is focused on the Neves Corvo deposit, an active copper mine. The project area is located between the Messejana Fault and the Portuguese/Spanish border which has been selected for the 3D geological and geophysical modelling study, based on high exploration potential of the Neves Corvo area (Oliveira et al. 2006, Relvas et al. 2006, Pereira et al. 2008, Rosa et al. 2008, Matos et al. 2011, Oliveira et al. 2013). In this study existing LNEG and AGC geological, geophysical and geochemistry databases were considered. New surveys were done: i) - A physical volcanology and palynostratigraphic age data study and log of the Cotovio drill-hole core (1,888 m, drilled by AGC). ii) - Interpretation of 280 km of Squid TEM performed by AGC. Based on the TEM data, significant conductors have been identified related with: shallow conductive cover, graphitic shale, black shale and sulphide mineralizations. The most important TEM conductors are related with the Neves Corvo massive sulphides lenses (1-10 Ωm). iii) - Ground and residual gravimetry studies including superficial directional derivatives to obtain the various directions of the late-Variscan faults, the main overthrusts and lithological structures. iv) - Detailed palynological sediment dating; v) - A seismic survey was conducted in the vicinities of the Neves Corvo mine totalling 82 km of profiles with target depth of over 10 km. A 3D regional model has been constructed for the selected IPB area using GoCAD, integrating the most critical information of the follow geological units: the lower unit BAFG Mértola Formation, the VSC, the Neves Corvo ores and the PQG. It incorporated surface regional geological maps, 168 drill-hole geological logs throughout the area, structural and tectonic data, former seismic sections, where available, and a digital terrain model. Chemical data from 42 selected drill-holes in order to outline in 3D the Cu distribution in the area. The results have already indicated new important guidelines for VHMS exploration and new regional correlations with the Neves Corvo mining area. The 3D modelling study was essential to the detail understanding of the complex IPB geological structures observed in the south of Portugal.

Gravity investigations of the Chesapeake Bay impact structure

USGS Publications Warehouse

Plescia, J.B.; Daniels, D.L.; Shah, A.K.

2009-01-01

The Chesapeake Bay impact structure is a complex impact crater, ??85 km in diameter, buried beneath postimpact sediments. Its main structural elements include a central uplift of crystalline bedrock, a surrounding inner crater filled with impact debris, and an annular faulted margin composed of block-faulted sediments. The gravity anomaly is consistent with that of a complex impact consisting of a central positive anomaly over the central uplift and an annular negative anomaly over the inner crater. An anomaly is not recognized as being associated with the faulted margin or the outer edge of the structure. Densities from the Eyreville drill core and modeling indicate a density contrast of ??0.3-0.6 g cm-3 between crystalline basement and the material that fills the inner crater (e.g., Exmore breccia and suevite). This density contrast is somewhat higher than for other impact structures, but it is a function of the manner in which the crater fill was deposited (as a marine resurge deposit). Modeling of the gravity data is consistent with a depth to basement of ??1600 m at the site of Eyreville drill hole and 800 m at the central uplift. Both depths are greater than the depth at which crystalline rocks were encountered in the cores, suggesting that the cored material is highly fractured para-allochthonous rock. ?? 2009 The Geological Society of America.

Tethyan Anhydrite Preserved in the Lower Ocean Crust of the Samail Ophiolite? Evidence from Oman Drilling Project Holes GT1A and 2A

NASA Astrophysics Data System (ADS)

Teagle, D. A. H.; Harris, M.; Crispini, L.; Deans, J. R.; Cooper, M. J.; Kelemen, P. B.; Alt, J.; Banerjee, N.; Shanks, W. C., III

2017-12-01

Anhydrite is important in mid-ocean ridge hydrothermal systems because of the high concentrations of calcium and sulfate in modern seawater and anhydrite's retrograde solubility. Because anhydrite hosts many powerful tracers of fluid-rock interactions (87Sr/86Sr, δ18O, δ34S, trace elements, fluid inclusions) it is useful for tracing the chemical evolution of hydrothermal recharge fluids and estimating time-integrated fluid fluxes. Anhydrite can form from heated seawater (>100°C), through water-rock reaction, or by mixing of seawater and hydrothermal fluids. Although abundant in active hydrothermal mounds, and predicted to form from downwelling, warming fluids during convection, anhydrite is rare in drill core from seafloor lavas, sheeted dikes and upper gabbros, with only minor amounts in ODP Holes 504B and 1256D. Because anhydrite can dissolve during weathering, its occurrence in ophiolites is unexpected. Instead, gypsum is present in Macquarie Island lavas and Miocene gypsum fills cavities within the Cretaceous Troodos ore deposits. Thus, the occurrence of numerous anhydrite veins in cores from the gabbroic lower crust of the Samail ophiolite in Oman was unanticipated. To our knowledge, anhydrite in Oman gabbros has not been previously reported. Oman Drilling Project Holes GT1A and GT2A were drilled into the Wadi Gideah section of the Wadi Tayin massif. Both recovered 400 m of continuous core from sections of layered gabbros (GT1) and the foliated-layered gabbro transition (GT2). Anhydrite is present throughout both holes, some in vein networks but more commonly as isolated 1-110 mm veins (>60 mm ave). Anhydrite is mostly the sole vein filling but can occur with greenschist minerals such as epidote, quartz, chlorite and prehnite. Anhydrite commonly exhibits prismatic and bladed textures but can also be capriciously microcrystalline. Though definitive cross cutting relationships are elusive, anhydrite veins cut across some greenschist veins. Anhydrite is deformed in faults with asymmetries consistent with normal senses of shear, suggestive of formation near the ridge, or at least before obduction. Gypsum is also present in both holes, but is clearly late stage and cuts across all earlier vein sets and deformation features. Notably, anhydrite was not observed in core from Hole GT3, in the dike-gabbro transition.

A 3-D view of field-scale fault-zone cementation from geologically ground-truthed electrical resistivity

NASA Astrophysics Data System (ADS)

Barnes, H.; Spinelli, G. A.; Mozley, P.

2015-12-01

Fault-zones are an important control on fluid flow, affecting groundwater supply, hydrocarbon/contaminant migration, and waste/carbon storage. However, current models of fault seal are inadequate, primarily focusing on juxtaposition and entrainment effects, despite the recognition that fault-zone cementation is common and can dramatically reduce permeability. We map the 3D cementation patterns of the variably cemented Loma Blanca fault from the land surface to ~40 m depth, using electrical resistivity and induced polarization (IP). The carbonate-cemented fault zone is a region of anomalously low normalized chargeability, relative to the surrounding host material. Zones of low-normalized chargeability immediately under the exposed cement provide the first ground-truth that a cemented fault yields an observable IP anomaly. Low-normalized chargeability extends down from the surface exposure, surrounded by zones of high-normalized chargeability, at an orientation consistent with normal faults in the region; this likely indicates cementation of the fault zone at depth, which could be confirmed by drilling and coring. Our observations are consistent with: 1) the expectation that carbonate cement in a sandstone should lower normalized chargeability by reducing pore-surface area and bridging gaps in the pore space, and 2) laboratory experiments confirming that calcite precipitation within a column of glass beads decreases polarization magnitude. The ability to characterize spatial variations in the degree of fault-zone cementation with resistivity and IP has exciting implications for improving predictive models of the hydrogeologic impacts of cementation within faults.

Compilation of Reprints Number 63.

DTIC Science & Technology

1986-03-01

Michel Be6, Stephen H1. Johnson, and E.F. Chiburis PRELIMINARY SEISMIC REFRACTION RESULTS USING A BOREHOLE SEISMOMETER IN DEEP SEA DRILLING PROJECT HOLE...refraction data with wells drilled on land and offshore reflection profiles permits tentative identification of geologic sequences on the basis of...PERIOD CO’VEAEO PRELIMINARY SEISMIC REFRACTION RESULTS USING A Rern BOREHOLE SEISMOMETER IN DEEP SEA DRILLING ~ rn PROJECT HOLE 395A 6.PERFORMING ORG

76 FR 76689 - Cibola National Forest, Mount Taylor Ranger District, NM, Mount Taylor Combined Exploratory Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-08

... the drill pad would measure 4 by 20 feet and be approximately 5 feet deep. An estimated 1.45 acres of... the drill pad would measure 8 by 10 feet and be approximately 6 feet deep. An estimated 42.64 acres of... the proposal will be posted on the project Web site at http://www.fs.fed.us/nepa/nepa_project_exp.php...

Pitfalls of negationist approach in communicating induced seismicity hazard in Italy

NASA Astrophysics Data System (ADS)

Mucciarelli, Marco

2013-04-01

Italy is a country rich in hydropower, geothermal wells, extraction/reinjection of hydrocarbons, but surprisingly from 1964 to date only three papers have been published on the seismicity induced by dams, two on the problem of seismicity induced by reinjection of fluids and one that studies the effect on seismicity by the variation of the groundwater regime possibly caused by the excavation of a tunnel or by climate change. What has happened in Italy to cause this (at least apparent) disregard for the induced seismicity? We must go back to 1964, after the catastrophe of Vajont. In that year, prof. Caloi, then principal geophysicist of the National Institute of Geophysics published a work in which he noted as the start of the reservoir impounding gave rise to a sequence of induced seismicity in the same rock shoulder that later collapsed causing an inundation claiming more than 2000 casualties. Since then induced seismicity is a taboo, constantly downplayed by companies and utilities, dismissed as impossible or communicated with artifacts like the constant use of the prefix "micro-". The Emilia 2012 occurred close to a site that was selected for a gas storage facility in an (un)confined aquifer. Regional government denied permission due to the vicinity to an active fault and the question was still pending in front of the National authority in charge of licensing the plant when the earthquake occurred. The local residents, that were opposing the gas storage, misinterpreted the motivation of the denial of permission, understanding that the fault would became active only if the storage was working. Thus they concluded the the earthquake occurred because the company performed secret drillings. Badly informed journalists mounted the case, calling it a "fracking" operation. Incredible it may sound, the governor of the Emilia-Romagna region appointed an international commission charged to investigate the relationship between drillings (not storage) and earthquakes. In the meantime, the L'Aquila sentence convinced the population that all the seismologists are corrupted, politically-linked flunkeys. Other hydrocarbons operation are now strongly opposed by residents and even geothermal projects, once hailed as eco-friendly, are blocked by local authorities on the base that "any drilling will cause earthquakes". The fact that there are not reliable expert in the field of induced seismicity is making things difficult to resolve, since no opinion is considered trustworthy.

Quantitative Risk Assessment (QRA) for an Underground Blowout Scenario in the Gulf of Mexico (GoM) Well

NASA Astrophysics Data System (ADS)

Tyagi, M.; Zulqarnain, M.

2017-12-01

Offshore oil and gas exploration and production operations, involve the use of some of the cutting edge and challenging technologies of the modern time. These technological complex operations involves the risk of major accidents as well, which have been demonstrated by disasters such as the explosion and fire on the UK production platform piper alpha, the Canadian semi-submersible drilling rig Ocean Ranger and the explosion and capsizing of Deepwater horizon rig in the Gulf of Mexico. By conducting Quantitative Risk Assessment (QRA), safety of various operations as well as their associated risks and significance during the entire life phase of an offshore project can be quantitatively estimated. In an underground blowout, the uncontrolled formation fluids from higher pressure formation may charge up shallower overlying low pressure formations or may migrate to sea floor. Consequences of such underground blowouts range from no visible damage at the surface to the complete loss of well, loss of drilling rig, seafloor subsidence or hydrocarbons discharged to the environment. These blowouts might go unnoticed until the over pressured sands, which are the result of charging from higher pressure reservoir due to an underground blowout. Further, engineering formulas used to estimate the fault permeability and thickness are very simple in nature and may add to uncertainty in the estimated parameters. In this study the potential of a deepwater underground blowout are assessed during drilling life phase of a well in Popeye-Genesis field reservoir in the Gulf of Mexico to estimate the time taken to charge a shallower zone to its leak-off test (LOT) value. Parametric simulation results for selected field case show that for relatively high permeability (k = 40mD) fault connecting a deep over-pressured zone to a shallower low-pressure zone of similar reservoir volumes, the time to recharge the shallower zone up to its threshold LOT value is about 135 years. If the ratio of the reservoir volumes for shallower to deeper zone is about 0.1, the recharging time significantly decreased to 24 years. Also, the hydrocarbons might possibly migrate through casing-wellbore annulus due to delamination fractures between cement interfaces with rock/casing and any other micro annulus gap not isolated by cement.

Geology of the Eymir iron mine, Edremit, Turkey

USGS Publications Warehouse

Jacobson, Herbert Samuel; Turet, Erdogan

1972-01-01

The Eymir mine near Edremit on Turkey's Aegean coast (long 27?30'E.,1at 39?36'N.) was investigated as part of the Maden Tetkik ve Arama Enstitutsu (MTA)-U. S. Geological Survey (USGS) mineral exploration and training project, for the purpose of increasing the known mineral reserves. Geologic mapping of the mine area indicates that hematite is restricted to argillized, silicified, and pyritized dacite and possibly andesite. Hematite is present as massive replacements, impregnations, disseminations, and fracture fillings. Most of the upper part of the iron deposit consists of a breccia composed mostly of silicifiled dacite fragments in a hematite matrix. The iron deposit was apparently formed in three steps: 1. Argillation, silicification, and pyritization of the andesitic lava and dacite units as a result of a regional intrusion. 2. Intrusion of the Dere Oren dacite stock, with associated faulting, fracturing, and breccia formation at the surface. 3. Deposition of hematite by oxidation of pyrite, and transfer of iron via fractures and faults by hydrothermal or meteoric fluids. The Eymir iron deposit is a blanketlike deposit on the crest of the Sivritepe-Eymir ridge. It is 1300 meters long, 80 to 450 meters wide, and has an average thickness of 18.6 meters. Drill holes in the deposit show the iron content to range from 32.0 to 57.6 percent, and to average 46.5 percent. Most of the gangue is silica, and an arsenic impurity averaging 0.39 percent is present. Most of the deposit cannot be utilized as iron ore because of low iron content, high silica content, and high arsenic content. Ore-dressing tests have shown that it is feasible to concentrate the low-grade material, producing a concentrate having increased iron content and reduced silica content. Tests have shown also that the arsenic content of the ore can be reduced substantially by sintering. Further tests and economic feasibility studies are necessary to determine whether an economic marketable iron ore can be produced. If such studies indicate the technical and economic feasibility of utilizing all the Eymir iron deposit, detailed additional studies are recommended including: 1. A detailed drilling and sampling program to include 60 drill holes averaging 40 meters in depth and detailed sampling of mine dumps. 2. Pilot-plant testing of concentration and sintering procedures. 3. A detailed pre-investment economic feasibility study.

Slip behaviour of carbonate-bearing faults subjected to fluid pressure stimulations

NASA Astrophysics Data System (ADS)

Collettini, Cristiano; Scuderi, Marco; Marone, Chris

2017-04-01

Earthquakes caused by fluid injection within reservoir have become an important topic of political and social discussion as new drilling and improved technologies enable the extraction of oil and gas from previously unproductive formations. During reservoir stimulation, the coupled interactions of frictional and fluid flow properties together with the stress state control both the onset of fault slip and fault slip behaviour. However, currently, there are no studies under controlled, laboratory conditions for which the effect of fluid pressure on fault slip behaviour can be deduced. To cover this gap, we have developed laboratory experiments where we monitor fault slip evolution at constant shear stress but with increasing fluid pressure, i.e. reducing the effective normal stress. Experiments have been conducted in the double direct shear configuration within a pressure vessel on carbonate fault gouge, characterized by a slightly velocity strengthening friction that is indicative of stable aseismic creep. In our experiments fault slip history can be divided in three main stages: 1) for high effective normal stress the fault is locked and undergoes compaction; 2) when the shear and effective normal stress reach the failure condition, accelerated creep is associated to fault dilation; 3) further pressurization leads to an exponential acceleration during fault compaction and slip localization. Our results indicate that fault weakening induced by fluid pressurization overcomes the velocity strengthening behaviour of calcite gouge, resulting in fast acceleration and earthquake slip. As applied to tectonic faults our results suggest that a larger number of crustal faults, including those slightly velocity strengthening, can experience earthquake slip due to fluid pressurization.

Surface mapping and drilling of extinct seafloor massive sulphide deposits (eSMS) from the TAG Hydrothermal Field, 26oN: A tale of two `Jaspers'

NASA Astrophysics Data System (ADS)

Stobbs, I. J.; Lusty, P.; Petersen, S.; Murton, B. J.

2017-12-01

Two extinct seafloor massive sulphide (eSMS) deposits within the TAG hydrothermal field, 26oN, mid-Atlantic ridge, were mapped and drilled: Southern Mound and the newly discovered `Rona Mound'. Surface mapping was undertaken by combining high definition video footage and high resolution bathymetry to interpret surface geological and geomorphological features. Drill core was recovered using the BGS RD2 robotic drilling rig. Surface mapping of the mounds revealed a superficial cover of carbonate and iron-oxyhydroxides sediments, observed to directly overly oxide coated sulphide material within fault scarps, which dissect the flanks of both mounds. Drilling at the summits of the mounds revealed similar stratigraphy to the mapping, with the addition of a coherent and dense layer of red-coloured silica-rich `jasper', up to 3m thick, underlying the sediments and overlying unoxidised massive sulphides. The jasper mineralogy is dominated by silica, with minor iron oxides and rare disseminated sulphides. It displays a range of complex textures including filamentous and dendritic iron oxides often coated in silica. Drill core samples show the material to be porous, but relatively impermeable. Strong and positive Eu (REE) anomalies indicates a hydrothermal origin with little evidence of a seawater signature (lack of negative Ce anomaly). Silica precipitation is associated with low temperature hydrothermal activity, chert and jasper materials are locally present within the nearby hydrothermally active TAG mound and are more widespread at low-temperature diffuse hydrothermal sites such as within the MESO field. We interpret the `jasper' layers to be a common product, formed during the waning, low temperature, stage of the hydrothermal cycle which may form an impermeable and resistant `cap' that protects the underlying massive sulphide ore body from oxidation and dissolution. The formation of a `jasper cap' could act automatically to preserve eSMS deposits when hydrothermal circulation ceases and is essential to preserving the resource potential of eSMS deposits. This `jasper' capping layer is important from an economic perspective, and reinforces the need for shallow sub-seafloor mapping as part of any deep-sea mineral exploration. This research received funding from the EC FP7 project Blue Mining (604500).

Structural controls on a geothermal system in the Tarutung Basin, north central Sumatra

NASA Astrophysics Data System (ADS)

Nukman, Mochamad; Moeck, Inga

2013-09-01

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW-SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE-WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.

The Maradi fault zone: 3-D imagery of a classic wrench fault in Oman

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neuhaus, D.

1993-09-01

The Maradi fault zone extends for almost 350 km in a north-northwest-south-southeast direction from the Oman Mountain foothills into the Arabian Sea, thereby dissecting two prolific hydrocarbon provinces, the Ghaba and Fahud salt basins. During its major Late Cretaceous period of movement, the Maradi fault zone acted as a left-lateral wrench fault. An early exploration campaign based on two-dimensional seismic targeted at fractured Cretaceous carbonates had mixed success and resulted in the discovery of one producing oil field. The structural complexity, rapidly varying carbonate facies, and uncertain fracture distribution prevented further drilling activity. In 1990 a three-dimensional (3-D) seismic surveymore » covering some 500 km[sup 2] was acquired over the transpressional northern part of the Maradi fault zone. The good data quality and the focusing power of 3-D has enabled stunning insight into the complex structural style of a [open quotes]textbook[close quotes] wrench fault, even at deeper levels and below reverse faults hitherto unexplored. Subtle thickness changes within the carbonate reservoir and the unconformably overlying shale seal provided the tool for the identification of possible shoals and depocenters. Horizon attribute maps revealed in detail the various structural components of the wrench assemblage and highlighted areas of increased small-scale faulting/fracturing. The results of four recent exploration wells will be demonstrated and their impact on the interpretation discussed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, J.S.

Several factors in the development of the East Wilmington oil field by THUMS Long Beach Co. are described. These include: critical path scheduling, complex stratigraphy, reservoir engineering, drilling program, production methods, pressure maintenance, crude oil processing, automation, transportation facilities, service lines, and electrical facilities. The complexity and closely scheduled operational events interwoven in the THUMS project demands a method for the carefully planned sequence of jobs to be done, beginning with island construction up through routine production and to the LACT system. These demanding requirements necessitated the use of a critical path scheduling program. It was decided to use themore » program evaluation technique. This technique is used to assign responsibilities for individual assignments to time assignments, and to keep the overall program on schedule. The stratigraphy of East Wilmington complicates all engineering functions associated with recovery methods and reservoir evaluation. At least 5 major faults are anticipated.« less

Deep Sea Drilling Project

ERIC Educational Resources Information Center

Kaneps, Ansis

1977-01-01

Discusses the goals of the ocean drilling under the International Phase of Ocean Drilling, which include sampling of the ocean crust at great depths and sampling of the sedimentary sequence of active and passive continental margins. (MLH)

Drilling the Oceanic Lower Crust and Mantle

DTIC Science & Technology

1989-11-01

East Pacific Rise near 21 ...A. Bideau, R.D. and Hekinian, R. 1983, Ultramafics and mafic rocks from the Garret transform fault near 13󈧢’S on the East Pacific Rise : igneous...Science Foundation. older crust formed at the East Pacific Rise . The JOIDES Planning Committee should immediately constitute a Deep Crustal

Strength of the San Andreas Fault Zone: Insight From SAFOD Cuttings and Core

NASA Astrophysics Data System (ADS)

Tembe, S.; Lockner, D. A.; Solum, J. G.; Morrow, C. A.; Wong, T.; Moore, D. E.

2005-12-01

Cuttings acquired during drilling of the SAFOD scientific hole near Parkfield, California offer a continuous physical record of the lithology across the San Andreas fault (SAF) zone and provide the only complete set of samples available for laboratory testing. Guided by XRD clay mineral analysis and velocity and gamma logs, we selected washed cuttings from depths spanning the main hole from 1.85 to 3.0 km true vertical depth. Cuttings were chosen to represent primary lithologic units as well as significant shear zones, including candidates for the currently active SAF. To determine frictional properties triaxial sliding tests were conducted on cylindrical granite blocks containing sawcuts inclined at 30° and filled with 1 mm-thick sample gouge layers. Tests were run at constant effective normal stresses of 10 and 40 MPa and constant pore pressure of 1 MPa. Samples were sheared up to 10.4 mm at room temperature and velocities of 1, 0.1 and 0.01 μm/s. Stable sliding behavior and overall strain hardening were observed in all tests. The coefficient of friction typically showed a modest decrease with increasing effective normal stress and mostly velocity strengthening was observed. Preliminary results yield coefficients of friction, μ, which generally fell into two clusters spanning the range of 0.45 to 0.8. The higher values of friction (~0.7 - 0.8) corresponded to quartzofeldspathic samples derived from granodiorites and arkoses encountered in the drill hole. Lower values of friction (0.45 - 0.55) were observed at depth intervals interpreted as shear zones based on enriched clay content, reduced seismic velocities and increased gamma radiation. Arguments for a weak SAF suggest coseismic frictional strength of μ = 0.1 to 0.2 yet the actual fault zone materials studied here appear consistently stronger. At least two important limitations exist for inferring in-situ fault strength from cuttings. (1) Clays and weak minerals are preferentially lost during drilling and therefore undersampled in the cuttings and (2) cuttings are mixed as they travel up the borehole. To test the validity of this approach sliding tests were conducted on core samples obtained from a prominent fault zone at 2.56 km (10062 ft measured depth). Coefficient of friction was measured to be 0.42-0.5, notably weaker than that for cuttings tested at this depth (~0.6) but similar to values obtained for other shear zones. This difference between core and cuttings from the equivalent depth is likely due to mixing, resulting in the averaging of mechanical properties over a 1 to 10 foot interval. Nevertheless, we find good agreement in the strength of materials obtained from shallow shear zones, an indication that some weak mineral phases are preserved in the cuttings. While our findings indicate that meaningful mechanical data can be derived from the cuttings, it should be noted that these observations do not represent an exhaustive study of SAF frictional strength. We continue to explore the effectiveness of the present technique by a variety of methods. For example, estimates of lost clay fractions determined from XRD analysis of unwashed cuttings can be used in the application of approximate mixing laws to correct friction measurements. In addition, comparisons of strength of cuttings and corresponding sidewall cores will help refine our results. While the analysis of cuttings provides the best fault zone strength data to date, unresolved questions show the importance of collecting continuous core in Phase 3 drilling planned for 2007.

Structure of Suasselkä Postglacial Fault in northern Finland obtained by analysis of ambient seismic noise

NASA Astrophysics Data System (ADS)

Afonin, Nikita; Kozlovskaya, Elena

2016-04-01

Understanding inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of ambient seismic noise recorded by the temporary DAFNE array in northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä post-glacial fault (SPGF) that was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised the area of about 20 to 100 km and consisted of 8 short-period and 4 broad-band 3-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September, 2011-May, 2013. Recordings of the array have being analyzed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä Gold Mine. As a result, we found several dozens of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate correspondent surface wave dispersion curves. After that S-wave velocity models were obtained as a result of dispersion curves inversion using Geopsy software. The results suggest that the area of the SPGF corresponds to a narrow region of low S-wave velocities surrounded by rocks with high S-wave velocities. We interpret this low velocity region as a non-healed mechanically weak fault damage zone (FDZ) remained after the last major earthquake that occurred after the last glaciation. Seismic instruments for the DAFNE/FINLAND experiment were provided by the institute of Seismology of the University of Helsinki and by the Sodankylä Geophysical Observatory. The study was partly funded by Posiva Oy and Geological Survey of Finland. DAFNE/FINLAND Working Group: Ilmo Kukkonen Pekka Heikkinen Kari Komminaho Elena Kozlovskaya Riitta Hurskainen Tero Raita Hanna Silvennoinen

An overview of results from the CO2SINK 3D baseline seismic survey at Ketzin, Germany

NASA Astrophysics Data System (ADS)

Juhlin, C.; Giese, R.; Cosma, C.; Kazemeini, H.; Juhojuntti, N.; Lüth, S.; Norden, B.; Förster, A.; Yordkayhun, S.

2009-04-01

A 3D seismic survey was acquired at the CO2SINK project site over the Ketzin anticline in the fall of 2005. Main objectives of the survey were (1) to verify earlier geological interpretations of the structure based on vintage 2D seismic and borehole data, (2) to provide, if possible, an understanding of the structural geometry for flow pathways within the reservoir, (3) a baseline for later evaluation of the time evolution of rock properties as CO2 is injected into the reservoir, and (4) detailed sub-surface images near the injection borehole for planning of the drilling operations. Overlapping templates with 5 receiver lines containing 48 active channels in each template were used for the acquisition. In each template, 200 nominal source points were activated using an accelerated weight drop, giving a nominal fold of 25. Due to logistics, the number of actual source points in each template varied. In spite of the relatively low fold and the simple source used, data quality is generally good with the uppermost 1000 m being well imaged. Data processing results clearly show a fault system across the top of the Ketzin anticline that is termed the Central Graben Fault Zone (CGFZ). The fault zone consists of west-southwest-east-northeast- to east-west-trending normal faults bounding a 600-800 m wide graben. Within the Jurassic section, discrete faults are well developed, and the main graben-bounding faults have throws of up to 30 m. At shallower levels, the fault system appears to disappear in the Tertiary Rupelian clay. The main bounding faults of the CGFZ can be traced downwards to the top of the Weser Formation and possibly to the Stuttgart level, the target formation for CO2 injection. No faults were imaged near the injection site on the southern limb of the anticline. Remnant gas, cushion and residual gas from a previous natural gas storage facility at the site, is present near the top of the anticline in the depth interval of about 250-400 m and has a clear seismic signature. In addition to the standard processing and interpretation applied, attribute analysis, detailed shallow reflection seismic processing, tomographic inversion of first arrival times, and initial seismic modeling of the CO2 response have been performed. Attribute analysis of the target horizon using the continuous wavelet transform indicates that the injection site penetrates the target reservoir near the edge of a north-northwest-south-southeast striking channel.

Interpretation of a 3D Seismic-Reflection Volume in the Basin and Range, Hawthorne, Nevada

NASA Astrophysics Data System (ADS)

Louie, J. N.; Kell, A. M.; Pullammanappallil, S.; Oldow, J. S.; Sabin, A.; Lazaro, M.

2009-12-01

A collaborative effort by the Great Basin Center for Geothermal Energy at the University of Nevada, Reno, and Optim Inc. of Reno has interpreted a 3d seismic data set recorded by the U.S. Navy Geothermal Programs Office (GPO) at the Hawthorne Army Depot, Nevada. The 3d survey incorporated about 20 NNW-striking lines covering an area of approximately 3 by 10 km. The survey covered an alluvial area below the eastern flank of the Wassuk Range. In the reflection volume the most prominent events are interpreted to be the base of Quaternary alluvium, the Quaternary Wassuk Range-front normal fault zone, and sequences of intercalated Tertiary volcanic flows and sediments. Such a data set is rare in the Basin and Range. Our interpretation reveals structural and stratigraphic details that form a basis for rapid development of the geothermal-energy resources underlying the Depot. We interpret a map of the time-elevation of the Wassuk Range fault and its associated splays and basin-ward step faults. The range-front fault is the deepest, and its isochron map provides essentially a map of "economic basement" under the prospect area. There are three faults that are the most readily picked through vertical sections. The fault reflections show an uncertainty in the time-depth that we can interpret for them of 50 to 200 ms, due to the over-migrated appearance of the processing contractor’s prestack time-migrated data set. Proper assessment of velocities for mitigating the migration artifacts through prestack depth migration is not possible from this data set alone, as the offsets are not long enough for sufficiently deep velocity tomography. The three faults we interpreted appear as gradients in potential-field maps. In addition, the southern boundary of a major Tertiary graben may be seen within the volume as the northward termination of the strong reflections from older Tertiary volcanics. Using a transparent volume view across the survey gives a view of the volcanics in full, providing a clear picture of prominent structures. Potential drill targets and areas of development are defined within the data volume by the intersections of the fault surfaces with the tracked, strong stratigraphic reflections. Target volumes for drilling and development are defined by the intersections of the faults and bright-spot stratigraphy, and their uncertainty bounds. There are a few such intersections present within the 3d volume. Analyzing seismic attributes gives the opportunity to identify characteristics common in geothermal environments.

Robotic and Human-Tended Collaborative Drilling Automation for Subsurface Exploration

NASA Technical Reports Server (NTRS)

Glass, Brian; Cannon, Howard; Stoker, Carol; Davis, Kiel

2005-01-01

Future in-situ lunar/martian resource utilization and characterization, as well as the scientific search for life on Mars, will require access to the subsurface and hence drilling. Drilling on Earth is hard - an art form more than an engineering discipline. Human operators listen and feel drill string vibrations coming from kilometers underground. Abundant mass and energy make it possible for terrestrial drilling to employ brute-force approaches to failure recovery and system performance issues. Space drilling will require intelligent and autonomous systems for robotic exploration and to support human exploration. Eventual in-situ resource utilization will require deep drilling with probable human-tended operation of large-bore drills, but initial lunar subsurface exploration and near-term ISRU will be accomplished with lightweight, rover-deployable or standalone drills capable of penetrating a few tens of meters in depth. These lightweight exploration drills have a direct counterpart in terrestrial prospecting and ore-body location, and will be designed to operate either human-tended or automated. NASA and industry now are acquiring experience in developing and building low-mass automated planetary prototype drills to design and build a pre-flight lunar prototype targeted for 2011-12 flight opportunities. A successful system will include development of drilling hardware, and automated control software to operate it safely and effectively. This includes control of the drilling hardware, state estimation of both the hardware and the lithography being drilled and state of the hole, and potentially planning and scheduling software suitable for uncertain situations such as drilling. Given that Humans on the Moon or Mars are unlikely to be able to spend protracted EVA periods at a drill site, both human-tended and robotic access to planetary subsurfaces will require some degree of standalone, autonomous drilling capability. Human-robotic coordination will be important, either between a robotic drill and humans on Earth, or a human-tended drill and its visiting crew. The Mars Analog Rio Tinto Experiment (MARTE) is a current project that studies and simulates the remote science operations between an automated drill in Spain and a distant, distributed human science team. The Drilling Automation for Mars Exploration (DAME) project, by contrast: is developing and testing standalone automation at a lunar/martian impact crater analog site in Arctic Canada. The drill hardware in both projects is a hardened, evolved version of the Advanced Deep Drill (ADD) developed by Honeybee Robotics for the Mars Subsurface Program. The current ADD is capable of 20m, and the DAME project is developing diagnostic and executive software for hands-off surface operations of the evolved version of this drill. The current drill automation architecture being developed by NASA and tested in 2004-06 at analog sites in the Arctic and Spain will add downhole diagnosis of different strata, bit wear detection, and dynamic replanning capabilities when unexpected failures or drilling conditions are discovered in conjunction with simulated mission operations and remote science planning. The most important determinant of future 1unar and martian drilling automation and staffing requirements will be the actual performance of automated prototype drilling hardware systems in field trials in simulated mission operations. It is difficult to accurately predict the level of automation and human interaction that will be needed for a lunar-deployed drill without first having extensive experience with the robotic control of prototype drill systems under realistic analog field conditions. Drill-specific failure modes and software design flaws will become most apparent at this stage. DAME will develop and test drill automation software and hardware under stressful operating conditions during several planned field campaigns. Initial results from summer 2004 tests show seven identifi distinct failure modes of the drill: cuttings-removal issues with low-power drilling into permafrost, and successful steps at executive control and initial automation.

Method and apparatus for in-situ detection and isolation of aircraft engine faults

NASA Technical Reports Server (NTRS)

Bonanni, Pierino Gianni (Inventor); Brunell, Brent Jerome (Inventor)

2007-01-01

A method for performing a fault estimation based on residuals of detected signals includes determining an operating regime based on a plurality of parameters, extracting predetermined noise standard deviations of the residuals corresponding to the operating regime and scaling the residuals, calculating a magnitude of a measurement vector of the scaled residuals and comparing the magnitude to a decision threshold value, extracting an average, or mean direction and a fault level mapping for each of a plurality of fault types, based on the operating regime, calculating a projection of the measurement vector onto the average direction of each of the plurality of fault types, determining a fault type based on which projection is maximum, and mapping the projection to a continuous-valued fault level using a lookup table.

In situ stress variations at the Variscan deformation front — Results from the deep Aachen geothermal well

NASA Astrophysics Data System (ADS)

Trautwein-Bruns, Ute; Schulze, Katja C.; Becker, Stephan; Kukla, Peter A.; Urai, Janos L.

2010-10-01

In 2004 the 2544 m deep RWTH-1 well was drilled in the city centre of Aachen to supply geothermal heat for the heating and cooling of the new student service centre "SuperC" of RWTH Aachen University. Aachen is located in a complex geologic and tectonic position at the northern margin of the Variscan deformation front at the borders between the Brabant Massif, the Hohes Venn/Eifel areas and the presently active rift zone of the Lower Rhine Embayment, where existing data on in situ stress show complex changes over short distances. The borehole offers a unique opportunity to study varying stress regimes in this area of complex geodynamic evolution. This study of the in situ stresses is based on the observation of compressive borehole breakouts and drilling-induced tensile fractures in electrical and acoustic image logs. The borehole failure analysis shows that the maximum horizontal stress trends SE-NW which is in accordance with the general West European stress trend. Stress magnitudes modelled in accordance to the Mohr-Coulomb Theory of Sliding Friction indicate minimum and maximum horizontal stress gradients of 0.019 MPa/m and 0.038 MPa/m, respectively. The occurrence of drilling-induced tensile failure and the calculated in situ stress magnitudes are consistent with a model of strike-slip deformation. The observed strike-slip faulting regime supports the extension of the Brabant Shear Zone proposed by Ahorner (1975) into the Aachen city area, where it joins the major normal faulting set of the Roer Valley Graben zone. This intersection of the inherited Variscan deformation grain and the Cenozoic deformation resulting in recent strike-slip and normal faulting activity proves the tectonically different deformation responses over a short distance between the long-lived Brabant Massif and the Cenozoic Rhine Rift System.

Identification of natural fractures and in situ stress at Rantau Dedap geothermal field

NASA Astrophysics Data System (ADS)

Artyanto, Andika; Sapiie, Benyamin; Idham Abdullah, Chalid; Permana Sidik, Ridwan

2017-12-01

Rantau Dedap Area is a geothermal field which is located in Great Sumatra Fault (GSF). The fault and fracture are main factor in the permeability of the geothermal system. However, not all faults and fractures have capability of to flow the fluids. Borehole image log is depiction of the borehole conditions, it is used to identify the natural fractures and drilling induced fracture. Both of them are used to identify the direction of the fracture, direction of maximum horizontal stress (SHmax), and geomechanics parameters. The natural fractures are the results of responses to stress on a rock and permeability which controlling factor in research area. Breakouts is found in this field as a trace of drilling induced fracture due to in situ stress work. Natural fractures are strongly clustered with true strike trending which first, second, and third major direction are N170°E - N180°E (N-S), N60°E - N70°E (NE-SW), and N310°E - N320°E (NW-SE), while the dominant dip is 80° -90°. Based on borehole breakout analysis, maximum horizontal stress orientation is identified in N162°E - N204°E (N-S) and N242°E (NE-SW) direction. It’s constantly similar with regional stress which is affected by GSF. Several parameters have been identified and analyzed are SHmax, SHmin, and Sy. It can be concluded that Rantau Dedap Geothermal Field is affected by strike-slip regime. The determination of in situ stress and natural fractures are important to study the pattern of permeability which is related to the fault in reservoir of this field.

Post-magmatic tectonic deformation of the outer Izu-Bonin-Mariana forearc system: initial results of IODP Expedition 352

NASA Astrophysics Data System (ADS)

Kurz, Walter; Ferré, Eric C.; Robertson, Alastair; Avery, Aaron; Christeson, Gail L.; Morgan, Sally; Kutterorf, Steffen; Sager, William W.; Carvallo, Claire; Shervais, John; Party IODP Expedition 352, Scientific

2015-04-01

IODP Expedition 352 was designed to drill through the entire volcanic sequence of the Bonin forearc. Four sites were drilled, two on the outer fore arc and two on the upper trench slope. Site survey seismic data, combined with borehole data, indicate that tectonic deformation in the outer IBM fore arc is mainly post-magmatic. Post-magmatic extension resulted in the formation of asymmetric sedimentary basins such as, for example, the half-grabens at sites 352-U1439 and 352-U1442 located on the upper trench slope. Along their eastern margins these basins are bounded by west-dipping normal faults. Sedimentation was mainly syn-tectonic. The lowermost sequence of the sedimentary units was tilted eastward by ~20°. These tilted bedding planes were subsequently covered by sub-horizontally deposited sedimentary beds. Based on biostratigraphic constraints, the minimum age of the oldest sediments is ~ 35 Ma; the timing of the sedimentary unconformities lies between ~ 27 and 32 Ma. At sites 352-U1440 and 352-U1441, located on the outer forearc, post-magmatic deformation resulted mainly in strike-slip faults possibly bounding the sedimentary basins. The sedimentary units within these basins were not significantly affected by post-sedimentary tectonic tilting. Biostratigraphic ages indicate that the minimum age of the basement-cover contact lies between ~29.5 and 32 Ma. Overall, the post-magmatic tectonic structures observed during Expedition 352 reveal a multiphase tectonic evolution of the outer IBM fore arc. At sites 352-U1439 and 352-U1442, shear with dominant reverse to oblique reverse displacement was localized along distinct subhorizontal cataclastic shear zones as well as steeply dipping slickensides and shear fractures. These structures, forming within a contractional tectonic regime, were either re-activated as or cross-cut by normal-faults as well as strike-slip faults. Extension was also accommodated by steeply dipping to subvertical mineralized veins and extensional fractures. Faults observed at sites 352-U1440 and 352-U1441 show mainly strike-slip. The sediments overlying the igneous basement, of maximum Late Eocene to Recent age, document ash and aeolian input, together with mass wasting of the fault-bounded sediment ponds.

Correlation of clayey gouge in a surface exposure of the San Andreas fault with gouge at depth from SAFOD: Implications for the role of serpentinite in fault mechanics

USGS Publications Warehouse

Moore, Diane E.; Rymer, Michael J.

2012-01-01

Magnesium-rich clayey gouge similar to that comprising the two actively creeping strands of the San Andreas Fault in drill core from the San Andreas Fault Observatory at Depth (SAFOD) has been identified in a nearby outcrop of serpentinite within the fault zone at Nelson Creek. Each occurrence of the gouge consists of porphyroclasts of serpentinite and sedimentary rocks dispersed in a fine-grained, foliated matrix of Mg-rich smectitic clays. The clay minerals in all three gouges are interpreted to be the product of fluid-assisted, shear-enhanced reactions between quartzofeldspathic wall rocks and serpentinite that was tectonically entrained in the fault from a source in the Coast Range Ophiolite. We infer that the gouge at Nelson Creek connects to one or both of the gouge zones in the SAFOD core, and that similar gouge may occur at depths in between. The special significance of the outcrop is that it preserves the early stages of mineral reactions that are greatly advanced at depth, and it confirms the involvement of serpentinite and the Mg-rich phyllosilicate minerals that replace it in promoting creep along the central San Andreas Fault.

Characterization of the Cretaceous aquifer structure of the Meskala region of the Essaouira Basin, Morocco

USGS Publications Warehouse

Hanich, L.; Zouhri, L.; Dinger, J.

2011-01-01

The aquifer of early Cretaceous age in the Meskala region of the Essaouira Basin is defined by interpretation of geological drilling data of oil and hydrogeological wells, field measurement and analysis of in situ fracture orientations, and the application of a morphostructural method to identify lineaments. These analyzes are used to develop a stratigraphic-structural model of the aquifer delimited by fault zones of two principal orientations: NNE and WNW. These fault zones define fault blocks that range in area from 4 to 150km2. These blocks correspond either to elevated zones (horsts) or depressed zones (grabens). This structural setting with faults blocks of Meskala region is in accordance with the structure of the whole Essaouira Basin. Fault zones disrupt the continuity of the aquifer throughout the study area, create recharge and discharge zones, and create dip to the units from approximately 10?? to near vertical in various orientations. Fracture measurements and morphometric-lineament analyzes help to identify unmapped faults, and represent features important to groundwater hydraulics and water quality within fault blocks. The above geologic features will enable a better understanding of the behaviour and hydro-geo-chemical and hydrodynamics of groundwater in the Meskala aquifer. ?? 2010 Elsevier Ltd.

IODP Expedition 338: Riser and Riserless Drilling Along the NanTroSEIZE Transect

NASA Astrophysics Data System (ADS)

Strasser, M.; Moore, G. F.; Dugan, B.; Kanagawa, K.; Toczko, S.

2013-12-01

Integrated Ocean Drilling Program (IODP) Expedition 338 provided new constraints on the Kumano Basin sediments, the accretionary prism inner wedge, the seaward extension of the megasplay fault, the architecture and mechanics of landslides, and the alteration of oceanic basement of the incoming Philippine Sea plate. This was accomplished through riser and riserless drilling, logging while drilling (LWD), and cuttings and core analysis. Cuttings and LWD analyses at Hole C0002F reveal two lithologic units in the prism inner wedge which are separated by a prominent fault zone at ~1640 mbsf. Mud-gases from the inner prism show high concentrations at the top of the wedge that decrease, but become more thermogenic, with depth. These data are from the previously unaccessed deeper part of the Nankai accretionary prism. Riserless coring at Site C0002 provided data across the gas hydrate zone of the Kumano Basin, across the Kumano Basin-accretionary prism unconformity, and in the uppermost accretionary prism. Within the Kumano basin section, gas and porewater geochemistry documents microbial methane gas in hydrates that are disseminated in sandy layers. Multiple penetrations of the Kumano Basin-accretionary prism boundary and 3D seismic data show that the boundary is erosive and complex. LWD (Site C0018) and coring and LWD (Site C0021) augment existing data to better understand submarine landslide dynamics and mass-transport deposit (MTD) emplacement processes. Previous coring at Site C0018 identified six MTDs, but only two MTD intervals were detected in resistivity images that show high angle, randomly oriented bedding. Site C0021, located more proximal to the MTD source, provides constraint on MTD variability. Correlation across the sites reveals a thick MTD with an erosional base characterized by a shear zone in muddy sediments vs. a translational basal surface within coarse volcaniclastic sand in the proximal and distal/lateral areas, respectively. LWD data and cores from Site C0022 characterize the uppermost 400 m of sediment near the tip of the megasplay fault zone where it approaches the seafloor. This fault zone is inferred to be located at the interval of 80-145 mbsf, based on biostratigraphic reversals, bedding dips >20°, porosity anomalies and a change in trend of interstitial water chemistry data. LWD at Site C0012 primarily yielded insights into the nature of the incoming oceanic crust. Two crustal units were identified based on LWD data. The upper unit had gamma ray variations that may indicate changes in the crustal alteration or sediment-basalt interlayering. The deeper unit has little variation in log properties, suggesting the presence of uniform or fresh basalt. Together these data provide new constraints on the overall architecture and mechanics of the Nankai subduction zone.

A Thermal Technique of Fault Nucleation, Growth, and Slip

NASA Astrophysics Data System (ADS)

Garagash, D.; Germanovich, L. N.; Murdoch, L. C.; Martel, S. J.; Reches, Z.; Elsworth, D.; Onstott, T. C.

2009-12-01

Fractures and fluids influence virtually all mechanical processes in the crust, but many aspects of these processes remain poorly understood largely because of a lack of controlled field experiments at appropriate scale. We have developed an in-situ experimental approach to create carefully controlled faults at scale of ~10 meters using thermal techniques to modify in situ stresses to the point where the rock fails in shear. This approach extends experiments on fault nucleation and growth to length scales 2-3 orders of magnitude greater than are currently possible in the laboratory. The experiments could be done at depths where the modified in situ stresses are sufficient to drive faulting, obviating the need for unrealistically large loading frames. Such experiments require an access to large rock volumes in the deep subsurface in a controlled setting. The Deep Underground Science and Engineering Laboratory (DUSEL), which is a research facility planned to occupy the workings of the former Homestake gold mine in the northern Black Hills, South Dakota, presents an opportunity for accessing locations with vertical stresses as large as 60 MPa (down to 2400 m depth), which is sufficient to create faults. One of the most promising methods for manipulating stresses to create faults that we have evaluated involves drilling two parallel planar arrays of boreholes and circulating cold fluid (e.g., liquid nitrogen) to chill the region in the vicinity of the boreholes. Cooling a relatively small region around each borehole causes the rock to contract, reducing the normal compressive stress throughout much larger region between the arrays of boreholes. This scheme was evaluated using both scaling analysis and a finite element code. Our results show that if the boreholes are spaced by ~1 m, in several days to weeks, the normal compressive stress can be reduced by 10 MPa or more, and it is even possible to create net tension between the borehole arrays. According to the Mohr-Coulomb strength criterion with standard Byerlee parameters, a fault will initiate before the net tension occurs. After a new fault is created, hot fluid can be injected into the boreholes to increase the temperature and reverse the direction of fault slip. This process can be repeated to study the formation of gouge, and how the properties of gouge control fault slip and associated seismicity. Instrumenting the site with arrays of geophones, tiltmeters, strain gauges, and displacement transducers as well as back mining - an opportunity provided by the DUSEL project - can reveal details of the fault geometry and gouge. We also expect to find small faults (with cm-scale displacement) during construction of DUSEL drifts. The same thermal technique can be used to induce slip on one of them and compare the “man-made” and natural gouges. The thermal technique appears to be a relatively simple way to rapidly change the stress field and either create slip on existing fractures or create new faults at scales up to 10 m or more.

Summary of IODP Expedition 344, CRISP-A2, offshore the Osa Peninsula, Costa Rica

NASA Astrophysics Data System (ADS)

Harris, R. N.; Sakaguchi, A.; Petronotis, K. E.

2013-12-01

The Costa Rica Seismogenesis Project (CRISP) is designed to elucidate the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. The CRISP study area is located offshore the Osa Peninsula where the incoming Cocos Ridge has lifted the seismogenic zone to within reach of scientific drilling. The incoming plate is characterized by low sediment supply, a fast convergence rate, abundant plate interface seismicity, and a change in subducting plate relief along strike. In addition to elucidating processes at erosional convergent margins, this project is complementary to other IODP deep fault drilling projects (e.g., NanTroSEIZE and J-FAST). Expedition 344 (23 October - 11 December, 2012) is the second expedition of CRISP Program A (Integrated Ocean Drilling Program Proposal 537A-Full5) that focused on the shallow lithologic, hydrologic, stress, and thermal conditions that lead to unstable slip in the seismogenic zone. With the exception of not reaching the décollement and the underthrust sediment at the toe site (U1412), Expedition 344 exceeded expectations. Material was recovered from the incoming Cocos plate (Sites U1381 and U1414), the toe of the margin (Site U1412), the mid-slope region (Site U1380), and the upper-slope region (Site U1413). Input sites U1381 and U1414 are characterized by anomalously high heat flow and the flow of fluids. These sites contained abundant ash that will be used to assess the impact of Cocos Ridge subduction on the evolution of the Central American volcanic arc. Although toe Site U1412 did not cross the décollement we did penetrate terrigenous sediments interrupted by a Miocene ooze that may reflect accretion of a frontal prism sliver. Mid-slope Site U1380 yielded a major result in that the upper plate material is not a mélange of oceanic material or the offshore extension of the Caribbean large igneous complex, but forearc basin material consisting of lithic sedimentary units. Upper-slope Site U1413 consists of a terrestrially sourced upper slope sequence consistent with high sediment accumulation rates. Preliminary biostratigraphic and paleomagnetic ages from Sites U1380 and U1413, the midslope and upper slope, respectively, yield sediment accumulation rates between ~290 and 590 m/m.y., an order of magnitude greater than estimated offshore the Nicoya Peninsula.

Sensitivity Studies of 3D Reservoir Simulation at the I-Lan Geothermal Area in Taiwan Using TOUGH2

NASA Astrophysics Data System (ADS)

Kuo, C. W.; Song, S. R.

2014-12-01

A large scale geothermal project conducted by National Science Council is initiated recently in I-Lan south area, northeastern Taiwan. The goal of this national project is to generate at least 5 MW electricity from geothermal energy. To achieve this goal, an integrated team which consists of various specialties are held together to investigate I-Lan area comprehensively. For example, I-Lan geological data, petrophysical analysis, seismicity, temperature distribution, hydrology, geochemistry, heat source study etc. were performed to build a large scale 3D conceptual model of the geothermal potential sites. In addition, not only a well of 3000m deep but also several shallow wells are currently drilling to give us accurate information about the deep underground. According to the current conceptual model, the target area is bounded by two main faults, Jiaosi and Choshui faults. The geothermal gradient measured at one drilling well (1200m) is about 49.1˚C/km. The geothermal reservoir is expected to occur at a fractured geological formation, Siling sandstone layer. The preliminary results of this area from all the investigations are used as input parameters to create a realistic numerical reservoir model. This work is using numerical simulator TOUGH2/EOS1 to study the geothermal energy potential in I-Lan area. Once we can successfully predict the geothermal energy potential in this area and generate 5 MW electricity, we can apply the similar methodology to the other potential sites in Taiwan, and therefore increase the percentage of renewable energy in the generation of electricity. A large scale of three-dimensional subsurface geological model is built mainly based on the seismic exploration of the subsurface structure and well log data. The dimensions of the reservoir model in x, y, and z coordinates are 20x10x5 km, respectively. Once the conceptual model and the well locations are set up appropriately based on the field data, sensitivity studies on production and injection rates, heat source, fractures, and all the relevant parameters are performed to evaluate their effects on temperature distribution of reservoir for 30 years. Through these sensitivity studies, we can design the better geothermal system in I-Lan area and reduce the risk of exploitation.

Metamorphism Near the Dike-Gabbro Transition in the Ocean Crust Based on Preliminary Results from Oman Drilling Project Hole GT3A

NASA Astrophysics Data System (ADS)

Manning, C. E.; Nozaka, T.; Harris, M.; Michibayashi, K.; de Obeso, J. C.; D'Andres, J.; Lefay, R.; Leong, J. A. M.; Zeko, D.; Kelemen, P. B.; Teagle, D. A. H.

2017-12-01

Oman Drilling Project Hole GT3A intersected 400 m of altered basaltic dikes, gabbros, and diorites. The 100% recovery affords an unprecedented opportunity to study metamorphism and hydrothermal alteration near the dike-gabbro transition in the ocean crust. Hydrothermal alteration is ubiquitous; all rocks are at least moderately altered, and mean alteration intensity is 54%. The earliest alteration in all rock types is background replacement of igneous minerals, some of which occurred at clinopyroxene amphibolite facies, as indicated by brown-green hornblende, calcic plagioclase, and secondary cpx. In addition, background alteration includes greenschist, subgreenschist, and zeolite facies minerals. More extensive alteration is locally observed in halos around veins, patches, and zones related to deformation. Dense networks of hydrothermal veins record a complex history of fluid-rock alteration. During core description, 10,727 individual veins and 371 vein networks were logged in the 400 m of Hole GT3A. The veins displayed a range of textures and connectivities. The total density of veins in Hole GT3A is 26.8 veins m-1. Vein density shows no correlation with depth, but may be higher near dike margins and faults. Vein minerals include amphibole, epidote, quartz, chlorite, prehnite, zeolite (chiefly laumontite) and calcite in a range of combinations. Analysis of crosscutting relations leads to classification of 4 main vein types. In order of generally oldest to youngest these are: amphibole, quartz-epidote-chlorite (QEC), zeolite-prehnite (ZP), and calcite. QEC and ZP vein types may contain any combination of minerals except quartz alone; veins filled only by quartz may occur at any relative time. Macroscopic amphibole veins are rare and show no variation with depth. QEC vein densities appear to be higher (>9.3 veins m-1) in the upper 300 m of GT3A, where dikes predominate. In contrast, there are 5.5 veins m-1 at 300-400 m, where gabbros and diorites are abundant. ZP veins increase in density downhole; the highest density of 17.5 ZP veins/m occurs in the lowest 100 m where substantial faulting is observed. Equilibrium coexistence of laumontite and prehnite in ZP veins implies formation at 100-250 °C, lower than amphibole and QEC veins. Calcite veins are abundant only in the uppermost 100 m of the hole.

The Marysville, Montana Geothermal Project

NASA Technical Reports Server (NTRS)

Mcspadden, W. R.; Stewart, D. H.; Kuwada, J. T.

1974-01-01

Drilling the first geothermal well in Montana presented many challenges, not only in securing materials and planning strategies for drilling the wildcat well but also in addressing the environmental, legal, and institutional issues raised by the request for permission to explore a resource which lacked legal definition. The Marysville Geothermal Project was to investigate a dry hot rock heat anomaly. The well was drilled to a total depth of 6790 feet and many fractured water bearing zones were encountered below 1800 feet.

Stress geomechanical model application: Stress tensor evaluation in recent Nankai subduction zone, SW Japan

NASA Astrophysics Data System (ADS)

Wu, H. Y.; Chan, C. H.

2016-12-01

Nowadays, IODP keeps investigating the scientific drilling in Nakai of southwest Japan from 2006. During this decade, we collected the massive logging data and core samples in this area for determining the stress evolution in this interseimic period after 1944 Tonakai earthquake. One of key assumption in Nankai seismogenic zone is the stress accumulation on the plate boundary should be the thrust-fault stress regime (SHmax>Shmin> Sv). In this research, the slip-deficit model is used to determine the wide scale stress field. The drilled IODP well sites are designed to be the fine control points. Based on the multiple ICDP expeditions near the Nankai trough (C0002A, F, and P) in different depths, the three dimensional stress estimation can be confirmed with the lateral boreholes loggings. Even the recently drilling did not reach the subduction zone, our model provides the considerable results by the reliable boundary conditions. This model simulated the stress orientation and magnitude generated by the slip-deficit model, area seismicity, and borehole loggings. Our results indicated that the stress state keeps in normal-faulting stress regime in our research area, even near the Nankai trough. Although the stress magnitude is increasing with the depth, one of horizontal principal stresses (Shmin) is hardly greater than the vertical stress (over-burden weight) in the reachable depth (>10km). This result implies the pore-pressure anomaly would happen during the slip and the stress state would be varied in different stages when event occurred

Physical properties of fault zone rocks from SAFOD: Tying logging data to high-pressure measurements on drill core

NASA Astrophysics Data System (ADS)

Jeppson, T.; Tobin, H. J.

2013-12-01

In the summer of 2005, Phase 2 of the San Andreas Fault Observatory at Depth (SAFOD) borehole was completed and logged with wireline tools including a dipole sonic tool to measure P- and S-wave velocities. A zone of anomalously low velocity was detected from 3150 to 3414 m measured depth (MD), corresponding with the subsurface location of the San Andreas Fault Zone (SAFZ). This low velocity zone is 5-30% slower than the surrounding host rock. Within this broad low-velocity zone, several slip surfaces were identified as well as two actively deforming shear zones: the southwest deformation zone (SDZ) and the central deformation zone (CDZ), located at 3192 and 3302 m MD, respectively. The SAFZ had also previously been identified as a low velocity zone in seismic velocity inversion models. The anomalously low velocity was hypothesized to result from either (a) brittle deformation in the damage zone of the fault, (b) high fluid pressures with in the fault zone, or (c) lithological variation, or a combination of the above. We measured P- and S-wave velocities at ultrasonic frequencies on saturated 2.5 cm diameter core plug samples taken from SAFOD core obtained in 2007 from within the low velocity zone. The resulting values fall into two distinct groups: foliated fault gouge and non-gouge. Samples of the foliated fault gouge have P-wave velocities between 2.3-3.5 km/s while non-gouge samples lie between 4.1-5.4 km/s over a range of effective pressures from 5-70 MPa. There is a good correlation between the log measurements and laboratory values of P-and S wave velocity at in situ pressure conditions especially for the foliated fault gouge. For non-gouge samples the laboratory values are approximately 0.08-0.73 km/s faster than the log values. This difference places the non-gouge velocities within the Great Valley siltstone velocity range, as measured by logs and ultrasonic measurements performed on outcrop samples. As a high fluid pressure zone was not encountered during SAFOD drilling, we use the ultrasonic velocities of SAFOD core and analogous outcrop samples to determine if the velocity reduction is due to lithologic variations or the presence of deformational fabrics and alteration in the fault zone. Preliminary analysis indicates that while the decrease in velocity across the broad fault zone is heavily influenced by fractures, the extremely low velocities associated with the actively deforming zones are more likely caused by the development of scaly fabric with clay coatings on the fracture surfaces. Analysis of thin sections and well logs are used to support this interpretation.

Hydromechanical drilling device

DOEpatents

Summers, David A.

1978-01-01

A hydromechanical drilling tool which combines a high pressure water jet drill with a conventional roller cone type of drilling bit. The high pressure jet serves as a tap drill for cutting a relatively small diameter hole in advance of the conventional bit. Auxiliary laterally projecting jets also serve to partially cut rock and to remove debris from in front of the bit teeth thereby reducing significantly the thrust loading for driving the bit.

Active source monitoring at the Wenchuan fault zone: coseismic velocity change associated with aftershock event and its implication

NASA Astrophysics Data System (ADS)

Yang, Wei; Ge, Hongkui; Wang, Baoshan; Hu, Jiupeng; Yuan, Songyong; Qiao, Sen

2014-12-01

With the improvement of seismic observation system, more and more observations indicate that earthquakes may cause seismic velocity change. However, the amplitude and spatial distribution of the velocity variation remains a controversial issue. Recent active source monitoring carried out adjacent to Wenchuan Fault Scientific Drilling (WFSD) revealed unambiguous coseismic velocity change associated with a local M s5.5 earthquake. Here, we carry out forward modeling using two-dimensional spectral element method to further investigate the amplitude and spatial distribution of observed velocity change. The model is well constrained by results from seismic reflection and WFSD coring. Our model strongly suggests that the observed coseismic velocity change is localized within the fault zone with width of ~120 m rather than dynamic strong ground shaking. And a velocity decrease of ~2.0 % within the fault zone is required to fit the observed travel time delay distribution, which coincides with rock mechanical experiment and theoretical modeling.

HIGH-POWER TURBODRILL AND DRILL BIT FOR DRILLING WITH COILED TUBING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert Radtke; David Glowka; Man Mohan Rai

2008-03-31

Commercial introduction of Microhole Technology to the gas and oil drilling industry requires an effective downhole drive mechanism which operates efficiently at relatively high RPM and low bit weight for delivering efficient power to the special high RPM drill bit for ensuring both high penetration rate and long bit life. This project entails developing and testing a more efficient 2-7/8 in. diameter Turbodrill and a novel 4-1/8 in. diameter drill bit for drilling with coiled tubing. The high-power Turbodrill were developed to deliver efficient power, and the more durable drill bit employed high-temperature cutters that can more effectively drill hardmore » and abrasive rock. This project teams Schlumberger Smith Neyrfor and Smith Bits, and NASA AMES Research Center with Technology International, Inc (TII), to deliver a downhole, hydraulically-driven power unit, matched with a custom drill bit designed to drill 4-1/8 in. boreholes with a purpose-built coiled tubing rig. The U.S. Department of Energy National Energy Technology Laboratory has funded Technology International Inc. Houston, Texas to develop a higher power Turbodrill and drill bit for use in drilling with a coiled tubing unit. This project entails developing and testing an effective downhole drive mechanism and a novel drill bit for drilling 'microholes' with coiled tubing. The new higher power Turbodrill is shorter, delivers power more efficiently, operates at relatively high revolutions per minute, and requires low weight on bit. The more durable thermally stable diamond drill bit employs high-temperature TSP (thermally stable) diamond cutters that can more effectively drill hard and abrasive rock. Expectations are that widespread adoption of microhole technology could spawn a wave of 'infill development' drilling of wells spaced between existing wells, which could tap potentially billions of barrels of bypassed oil at shallow depths in mature producing areas. At the same time, microhole coiled tube drilling offers the opportunity to dramatically cut producers' exploration risk to a level comparable to that of drilling development wells. Together, such efforts hold great promise for economically recovering a sizeable portion of the estimated remaining shallow (less than 5,000 feet subsurface) oil resource in the United States. The DOE estimates this U.S. targeted shallow resource at 218 billion barrels. Furthermore, the smaller 'footprint' of the lightweight rigs utilized for microhole drilling and the accompanying reduced drilling waste disposal volumes offer the bonus of added environmental benefits. DOE analysis shows that microhole technology has the potential to cut exploratory drilling costs by at least a third and to slash development drilling costs in half.« less

Improved alignment of the Hengchun Fault (southern Taiwan) based on fieldwork, structure-from-motion, shallow drilling, and levelling data

NASA Astrophysics Data System (ADS)

Giletycz, Slawomir Jack; Chang, Chung-Pai; Lin, Andrew Tien-Shun; Ching, Kuo-En; Shyu, J. Bruce H.

2017-11-01

The fault systems of Taiwan have been repeatedly studied over many decades. Still, new surveys consistently bring fresh insights into their mechanisms, activity and geological characteristics. The neotectonic map of Taiwan is under constant development. Although the most active areas manifest at the on-land boundary of the Philippine Sea Plate and Eurasia (a suture zone known as the Longitudinal Valley), and at the southwestern area of the Western Foothills, the fault systems affect the entire island. The Hengchun Peninsula represents the most recently emerged part of the Taiwan orogen. This narrow 20-25 km peninsula appears relatively aseismic. However, at the western flank the peninsula manifests tectonic activity along the Hengchun Fault. In this study, we surveyed the tectonic characteristics of the Hengchun Fault. Based on fieldwork, four years of monitoring fault displacement in conjunction with levelling data, core analysis, UAV surveys and mapping, we have re-evaluated the fault mechanisms as well as the geological formations of the hanging and footwall. We surveyed features that allowed us to modify the existing model of the fault in two ways: 1) correcting the location of the fault line in the southern area of the peninsula by moving it westwards about 800 m; 2) defining the lithostratigraphy of the hanging and footwall of the fault. A bathymetric map of the southern area of the Hengchun Peninsula obtained from the Atomic Energy Council that extends the fault trace offshore to the south distinctively matches our proposed fault line. These insights, coupled with crust-scale tomographic data from across the Manila accretionary system, form the basis of our opinion that the Hengchun Fault may play a major role in the tectonic evolution of the southern part of the Taiwan orogen.

Constraints on the stress state of the San Andreas Fault with analysis based on core and cuttings from San Andreas Fault Observatory at Depth (SAFOD) drilling phases 1 and 2

USGS Publications Warehouse

Tembe, S.; Lockner, D.; Wong, T.-F.

2009-01-01

Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (?? 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. Some models assert that weak gouge and/or high pore pressure exist under static conditions while others consider strength loss or fluid pressure increase due to rapid coseismic fault slip. The present paper is composed of three parts. First, we develop generalized equations, based on and consistent with the Rice (1992) fault zone model to relate stress orientation and magnitude to depth-dependent coefficient of friction and pore pressure. Second, we present temperature-and pressure-dependent friction measurements from wet illite-rich fault gouge extracted from San Andreas Fault Observatory at Depth (SAFOD) phase 1 core samples and from weak minerals associated with the San Andreas Fault. Third, we reevaluate the state of stress on the San Andreas Fault in light of new constraints imposed by SAFOD borehole data. Pure talc (?????0.1) had the lowest strength considered and was sufficiently weak to satisfy weak fault heat flow and stress orientation constraints with hydrostatic pore pressure. Other fault gouges showed a systematic increase in strength with increasing temperature and pressure. In this case, heat flow and stress orientation constraints would require elevated pore pressure and, in some cases, fault zone pore pressure in excess of vertical stress. Copyright 2009 by the American Geophysical Union.

Direct Observations of In Situ Stress State in a 3 Kilometer Deep Borehole in the Upper Plate, Nankai Trough Subduction Zone: IODP Site C0002

NASA Astrophysics Data System (ADS)

Tobin, H. J.; Saffer, D. M.; Castillo, D. A.; Hirose, T.

2016-12-01

During IODP Expedition 348, borehole C0002F/N/P was advanced to a depth of 3058 m below the seafloor (mbsf) into the inner forearc accretionary wedge of the Nankai subduction zone (SW Japan), now the deepest scientific drilling ever into the ocean floor. The goals were to investigate the physical properties, structure, and state of stress deep within the hanging wall of a seismogenic subduction plate boundary. Mud pressure and gas monitoring, injection tests, leak-off tests (LOT), logging-while-drilling (LWD) measurements, and observations of mud losses and hole conditions provide both direct and indirect information about in situ pore pressure and stress state. The LOTs show that the minimum principal stress is consistently less than the vertical stress defined by the overburden, ruling out a thrust faulting stress state throughout the drilled section, and define a nearly linear gradient in Shmin from the seafloor to the base of the hole. Observations of mud loss and the lack of observed gas shows indicate that formation pore fluid pressure is not significantly (< 10 MPa) greater than hydrostatic. The maximum horizontal stress, estimated from borehole breakout width and pressure spikes during pack-off events, is close in magnitude to the vertical stress. Therefore the accretionary prism lies in either a normal or strike-slip faulting regime, or is transitional between the two, from 1 to 3 km depth. At 3002 mbsf we estimate that the effective stresses are: Sv' = 33 MPa; SHmax' = 25-36 MPa; and Shmin' = 18.5-21 MPa. Differential stresses are therefore low, on the order of 10-12 MPa, in the hanging wall of the subduction thrust. We conclude that (1) the inner wedge is not critically stressed in horizontal compression; (2) basal traction along the megathrust must be low in order to permit concurrent locking of the fault and low differential stresses deep within the upper plate; and (3) although low differential stresses may persist down to the plate boundary at 5000 mbsf, the maximum horizontal stress SHmax must transition to become greater than the vertical stress, either spatially below the base of the borehole, or temporally leading up to megathrust fault rupture, in order to drive slip on the megathrust.

Hawaii Scientific Drilling Project: Objectives, Successes, Surprises and Frustrations

NASA Astrophysics Data System (ADS)

Depaolo, D. J.; Stolper, E.; Thomas, D. M.

2008-12-01

The Hawaii Scientific Drilling Project (HSDP) is a long-running project undertaken with the objective of studying a mantle plume by drilling an extended sequence of lavas from a single Hawaiian volcano. The project originated with a proposal to NSF in late 1986 with the idea of drilling to the Moho under Hilo; the target depth was estimated at 12km, commensurate with the depth reached by the drilling program then being pursued by the USSR and that proposed in the U.S. for the southern Appalachians, and in line with the aspirations of the nascent DOSECC program. Subsequently, due to limitations in funding and reorganization of the drilling program into what later became the NSF Continental Dynamics Program, HSDP was re-scoped with the objective of drilling deeply enough (ca. 4.5km) to recover most of the eruptive history of a single volcano. The project first went to a pilot stage, which resulted in coring to a depth of 1.1km in late 1993. The pilot stage was relatively inexpensive (1M including science) and productive. Funding was then obtained from NSF and ICDP in 1995 (ca. 12M) with the objective of drilling to 4.5km. Drilling was originally planned for a five-year period, in two campaigns. The first campaign, in 1999, resulted in efficient coring to a depth of 3.1km over a period of 6 months; it used about 40 percent of the funds and was also highly productive. Deepening the hole below 3.1km turned out to be both difficult and expensive, although for interesting reasons. To facilitate deeper drilling the hole needed to be reamed to a larger diameter; but when this was done the well unexpectedly started to flow. We now know that there are several deep pressurized aquifers, with varying salt content, but these hydrological phenomena were totally unanticipated. A key finding, also unanticipated, is that cold seawater circulates through the volcanic pile in volumes sufficient to refrigerate the entire section below 700m depth to temperatures about 25 degrees below a normal geothermal gradient. In early 1999 when the first drilling campaign was organized, the price of oil was 10 USD (rigs and drilling crews were available and reasonably priced); in early 2003 when hole opening was being arranged, the price of oil was 30 USD, and for the coring campaigns in 2005 and 2007 it was 50 to 70 USD. For these reasons, and because trip times were longer and deeply buried pillow basalts more difficult to drill, the remainder of the project funds (and then some) were needed to deepen the hole from 3.1 to 3.5km. Nevertheless, the project obtained a nearly continuous, and virtually unweathered, core consisting of lava flows, hyaloclastite, minor intrusives and sediment from a 3260m section of the Mauna Kea volcano, covering an age range from 200 to over 600 ka. It also recovered a 250m and a 280m section of the Mauna Loa volcano. A wealth of geological, volcanological, petrological, geochemical, geomagnetic, geodynamic, hydrological, and geobiological data have come from the core and the well, and more are coming in. The unprecedented geochemical-petrological data sets are a major success, as is the fact that geochemists can work together, but the hoped-for detailed geochronology for the core has proven difficult to obtain.

Deep rock damage in the San Andreas Fault revealed by P- and S-type fault-zone-guided waves

USGS Publications Warehouse

Ellsworth, William L.; Malin, Peter E.

2011-01-01

Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA. This laterally extensive channel extends downwards to at least half way through the seismogenic crust, more than about 7 km. The channel supports not only the previously recognized Love-type- (FL) and Rayleigh-type- (FR) guided waves, but also a new fault-guided wave, which we name FF. As recorded 2.7 km underground, FF is normally dispersed, ends in an Airy phase, and arrives between the P- and S-waves. Modelling shows that FF travels as a leaky mode within the core of the fault zone. Combined with the drill core samples, well logs and the two other types of guided waves, FF at SAFOD reveals a zone of profound, deep, rock damage. Originating from damage accumulated over the recent history of fault movement, we suggest it is maintained either by fracturing near the slip surface of earthquakes, such as the 1857 Fort Tejon M 7.9, or is an unexplained part of the fault-creep process known to be active at this site.

Map and database of Quaternary faults in Venezuela and its offshore regions

USGS Publications Warehouse

Audemard, F.A.; Machette, M.N.; Cox, J.W.; Dart, R.L.; Haller, K.M.

2000-01-01

As part of the International Lithosphere Program’s “World Map of Major Active Faults,” the U.S. Geological Survey is assisting in the compilation of a series of digital maps of Quaternary faults and folds in Western Hemisphere countries. The maps show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. They are accompanied by databases that describe these features and document current information on their activity in the Quaternary. The project is a key part of the Global Seismic Hazards Assessment Program (ILP Project II-0) for the International Decade for Natural Hazard Disaster Reduction.The project is sponsored by the International Lithosphere Program and funded by the USGS’s National Earthquake Hazards Reduction Program. The primary elements of the project are general supervision and interpretation of geologic/tectonic information, data compilation and entry for fault catalog, database design and management, and digitization and manipulation of data in †ARCINFO. For the compilation of data, we engaged experts in Quaternary faulting, neotectonics, paleoseismology, and seismology.

An Investigation for Disposal of Drill Cuttings into Unconsolidated Sandstones and Clayey Sands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mese, Ali; Dvorkin, Jack; Shillinglaw, John

2000-09-11

This project include experimental data and a set of models for relating elastic moduli/porosity/texture and static-to-dynamic moduli to strength and failure relationships for unconsolidated sands and clayey sands. The results of the project should provide the industry with a basis for wider use of oil base drilling fluids in water sensitive formations by implementing drill cutting injection into existing wells at abandoned formations and controlling fracture geometry to prevent ground water contamination.

K-Ar constraints on fluid-rock interaction and dissolution-precipitation events within the actively creeping shear zones from SAFOD cores

NASA Astrophysics Data System (ADS)

Ali, S.; Hemming, S. R.; Torgersen, T.; Fleisher, M. Q.; Cox, S. E.; Stute, M.

2009-12-01

The San Andreas Fault Observatory at Depth (SAFOD) was drilled to study the physical and chemical processes responsible for faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD drill cores show multiple zones of alteration and deformation due to fluid-rock interaction in the fault rocks(Schleicher et al. 2008). In context of fluid studies in the SAFZ, noble gas and potassium measurements were performed on solid samples of sedimentary rocks obtained from drill cores across the fault (3050-4000m-MD). We used a combination of 40Ar/39Ar and K-Ar methods on crushed samples of mudrock with variable amounts of visible slickensides to constrain the degree of resetting of the K-Ar system across the San Andreas Fault zone. 40Ar/39Ar was analyzed from small fragments (sand sized grains) while K-Ar was measured in crushed bulk rock samples (100-250 mg for Ar, and 5-10 mg for K analyses). The apparent 40Ar/39Ar ages based on single step laser fusion of small fragments corresponding to the detrital component in the coarse fraction, show varying ages ranging from the provenance age to <13Ma. Although more data are needed to make detailed comparisons, the apparent K-Ar ages of bulk samples in the fault zone are biased toward authigenic materials contained in the fine fraction, similar to the 40Ar/39Ar ages reported for mineralogical separates from very fine size fractions of samples obtained from 3065.98m-MD and 3294.89m-MD (Schleicher et al., submitted to Geology). The small samples measured for 40Ar/39Ar show scatter in the apparent ages, generally bracketing the bulk ages. However they are picked from sieved portions of the samples, and it is likely that there may be a loss of the younger (finer) material. Detrital provenance ages appear to be 50-60Ma in the Pacific Plate, and 100Ma in the North American Plate. 40Ar/39Ar ages within the SAFZ, as defined by geophysical logs (3200-3400m MD), are dominated by apparent detrital ages of ˜100Ma. More work is needed to test whether this is a real provenance age, or if there could be some systematic process that could lead to age bias towards older values. We observe nearly complete resetting of K-Ar ages, indicating that the K content is dominated by newly formed authigenic minerals as a result of fluid rock interaction in the SAFZ. Because the authigenic minerals are subject to successive dissolution-precipitation events over a range of time (3 to 0 Ma) and because the detrital component may not be fully reset, the K-Ar apparent ages (<300,000 years) in the SAFZ provide a maximum age on the resetting event. Similar trends of relatively young ages across the SAFZ compared to the surrounding country rock in the Pacific and North American Plates are also observed in the apparent fluid ‘ages’, corresponding to the fluid event responsible for the fluid-rock interaction in the fault (Ali et al. this session).

76 FR 78938 - Carpinteria Offshore Field Redevelopment Project-Developmental Drilling Into the Carpinteria...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... DEPARTMENT OF THE INTERIOR Bureau of Ocean Energy Management Carpinteria Offshore Field Redevelopment Project--Developmental Drilling Into the Carpinteria Offshore Field Oil and Gas Reserves... Lands Commission (CSLC) intend to jointly review a proposal to develop offshore oil and gas resources...

Geology of the undeveloped oil and gas fields of Central Offshore Santa Maria Basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milton, J.D.; Edwards, E.B.; Heck, R.G.

1996-01-01

Two prominent subsurface structural features of the Central Offshore Santa Maria Basin are the Hosgri fault system and the associated anticlinal fold trend. Exploratory drilling and 3D seismic mapping have delineated a series of oil and gas fields along this trend which underlie four federal units and one non-unitized lease. The units are named after local geography and are called the Lion Rock, Point Sal, Purisima Point and Santa Maria Units. The individual lease, OCS P-0409, overlies the San Miguel field. The Hosgri fault system trends northwest-southeast and effectively forms the eastern boundary of the oil and gas province. Lyingmore » semi-parallel with the fault are several anticlinal culminations which have trapped large volumes of oil and gas in the fractured Montery Formation. The Monterey is both source and reservoir rock, averaging 300 meters n thickness throughout the Central Basin. Development of the Monterey Formation as a reservoir rock was through diagensis and tectonism with resulting porosities-from 15 to 20% and permeability up to one Darcy. These parameters coupled with a high geothermal gradient facilitate the inflow rates of the viscous Monterey oil. Some 24 exploration and delineation wells have been drilled in this area and tested at rates ranging from a few hundred to several thousand barrels per day. Estimated oil reserves in the Central Offshore Santa Maria Basin total approximately 1 billion barrels.« less

Geology of the undeveloped oil and gas fields of Central Offshore Santa Maria Basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milton, J.D.; Edwards, E.B.; Heck, R.G.

1996-12-31

Two prominent subsurface structural features of the Central Offshore Santa Maria Basin are the Hosgri fault system and the associated anticlinal fold trend. Exploratory drilling and 3D seismic mapping have delineated a series of oil and gas fields along this trend which underlie four federal units and one non-unitized lease. The units are named after local geography and are called the Lion Rock, Point Sal, Purisima Point and Santa Maria Units. The individual lease, OCS P-0409, overlies the San Miguel field. The Hosgri fault system trends northwest-southeast and effectively forms the eastern boundary of the oil and gas province. Lyingmore » semi-parallel with the fault are several anticlinal culminations which have trapped large volumes of oil and gas in the fractured Montery Formation. The Monterey is both source and reservoir rock, averaging 300 meters n thickness throughout the Central Basin. Development of the Monterey Formation as a reservoir rock was through diagensis and tectonism with resulting porosities-from 15 to 20% and permeability up to one Darcy. These parameters coupled with a high geothermal gradient facilitate the inflow rates of the viscous Monterey oil. Some 24 exploration and delineation wells have been drilled in this area and tested at rates ranging from a few hundred to several thousand barrels per day. Estimated oil reserves in the Central Offshore Santa Maria Basin total approximately 1 billion barrels.« less

Permeability Evolution With Shearing of Simulated Faults in Unconventional Shale Reservoirs

NASA Astrophysics Data System (ADS)

Wu, W.; Gensterblum, Y.; Reece, J. S.; Zoback, M. D.

2016-12-01

Horizontal drilling and multi-stage hydraulic fracturing can lead to fault reactivation, a process thought to influence production from extremely low-permeability unconventional reservoir. A fundamental understanding of permeability changes with shear could be helpful for optimizing reservoir stimulation strategies. We examined the effects of confining pressure and frictional sliding on fault permeability in Eagle Ford shale samples. We performed shear-flow experiments in a triaxial apparatus on four shale samples: (1) clay-rich sample with sawcut fault, (2) calcite-rich sample with sawcut fault, (3) clay-rich sample with natural fault, and (4) calcite-rich sample with natural fault. We used pressure pulse-decay and steady-state flow techniques to measure fault permeability. Initial pore and confining pressures are set to 2.5 MPa and 5.0 MPa, respectively. To investigate the influence of confining pressure on fault permeability, we incrementally raised and lowered the confining pressure and measure permeability at different effective stresses. To examine the effect of frictional sliding on fault permeability, we slide the samples four times at a constant shear displacement rate of 0.043 mm/min for 10 minutes each and measure fault permeability before and after frictional sliding. We used a 3D Laser Scanner to image fault surface topography before and after the experiment. Our results show that frictional sliding can enhance fault permeability at low confining pressures (e.g., ≥5.0 MPa) and reduce fault permeability at high confining pressures (e.g., ≥7.5 MPa). The permeability of sawcut faults almost fully recovers when confining pressure returns to the initial value, and increases with sliding due to asperity damage and subsequent dilation at low confining pressures. In contrast, the permeability of natural faults does not fully recover. It initially increases with sliding, but then decreases with further sliding most likely due to fault gouge blocking fluid pathways.

Multi-scale Onland-Offshore Investigations of the New Caledonia Ophiolite, SW Pacific

NASA Astrophysics Data System (ADS)

Clerc, C. N.; Collot, J.; Sevin, B.; Patriat, M.; Etienne, S.; Iseppi, M.; Lesimple, S.; Jeanpert, J.; Mortimer, N. N.; Poli, S.; Pattier, F.; Juan, C.; Robineau, B.; Godard, M.; Cluzel, D.

2017-12-01

The Peridotite Nappe of New Caledonia is one of the largest ultramafic ophiolite in the World: it represents about one quarter of the 500 x 80 km island of Grande Terre. This extensive upper mantle unit was tectonically emplaced during the Eocene onto the northeastern edge of Zealandia continent. It is weakly deformed because it was not involved in a collision belt after obduction. A dome-shaped Eocene HP/LT metamorphic complex was exhumed across the fore-arc mantle lithosphere in the northern tip of the island. Post-obduction Miocene to Present coral reefs developed in shallow waters around Grande Terre and surrounding islands. In the perspective of a possible onshore/offshore drilling project (IODP/ICDP), we present recent advances in our understanding of offshore extensions of this ophiolite. To the south of New Caledonia, the offshore continuation of the ultramafic allochthon has been identified by dredges and by its geophysical signature as a continuous linear body that extends over a distance of more than 400 km at about 2000m bsl. Such water depths allow an unprecedented seismic reflection imaging of a drowned and well-preserved ophiolite. Seismic profiles show that the nappe has a flat-top, and is capped by carbonate reefs and dissected by several major normal faults. To the east of this presumed ultramafic body, Felicité Ridge is a 30 km wide, 350 km long, dome-shaped ridge, which may be interpreted as the possible southern extension of the HP/LT metamorphic complex observed onshore. Onshore, several 150 to 200 m long cores were drilled in the ophiolite and airborne electromagnetic allowed high-resolution imaging down to 400 m depth. These recent results allow identification of internal thrusts within the peridotite body and more superficial landslides. The analysis of polyphase fracturation and associated serpentinization brings new constraints on the tectonic evolution of the ophiolite and its subsequent weathering pattern. We integrate these data and discuss the chronology of pre-, syn-, and post-obduction tectonic events. But our limited access to the deep parts of the ophiolite calls for the necessity of planning an onshore/offshore deep drilling project.

Scientific Drilling of Impact Craters - Well Logging and Core Analyses Using Magnetic Methods (Invited)

NASA Astrophysics Data System (ADS)

Fucugauchi, J. U.; Perez-Cruz, L. L.; Velasco-Villarreal, M.

2013-12-01

Drilling projects of impact structures provide data on the structure and stratigraphy of target, impact and post-impact lithologies, providing insight on the impact dynamics and cratering. Studies have successfully included magnetic well logging and analyses in core and cuttings, directed to characterize the subsurface stratigraphy and structure at depth. There are 170-180 impact craters documented in the terrestrial record, which is a small proportion compared to expectations derived from what is observed on the Moon, Mars and other bodies of the solar system. Knowledge of the internal 3-D deep structure of craters, critical for understanding impacts and crater formation, can best be studied by geophysics and drilling. On Earth, few craters have yet been investigated by drilling. Craters have been drilled as part of industry surveys and/or academic projects, including notably Chicxulub, Sudbury, Ries, Vredefort, Manson and many other craters. As part of the Continental ICDP program, drilling projects have been conducted on the Chicxulub, Bosumtwi, Chesapeake, Ries and El gygytgyn craters. Inclusion of continuous core recovery expanded the range of paleomagnetic and rock magnetic applications, with direct core laboratory measurements, which are part of the tools available in the ocean and continental drilling programs. Drilling studies are here briefly reviewed, with emphasis on the Chicxulub crater formed by an asteroid impact 66 Ma ago at the Cretaceous/Paleogene boundary. Chicxulub crater has no surface expression, covered by a kilometer of Cenozoic sediments, thus making drilling an essential tool. As part of our studies we have drilled eleven wells with continuous core recovery. Magnetic susceptibility logging, magnetostratigraphic, rock magnetic and fabric studies have been carried out and results used for lateral correlation, dating, formation evaluation, azimuthal core orientation and physical property contrasts. Contributions of magnetic studies on impact age, cratering, target-impactite stratigraphy, ejecta, impact dynamics, hydrothermal alterations and post-impact processes are presented. The challenges and perspectives of drilling studies of impact craters are discussed.

Constraints on the stress state of the San Andreas fault with analysis based on core and cuttings from SAFOD drilling phases I and II

USGS Publications Warehouse

Lockner, David A.; Tembe, Cheryl; Wong, Teng-fong

2009-01-01

Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (m < 0.2) or strength consistent with standard laboratory tests (m > 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. Some models assert that weak gouge and/or high pore pressure exist under static conditions while others consider strength loss or fluid pressure increase due to rapid coseismic fault slip. The present paper is composed of three parts. First, we develop generalized equations, based on and consistent with the Rice (1992) fault zone model to relate stress orientation and magnitude to depth-dependent coefficient of friction and pore pressure. Second, we present temperature- and pressure-dependent friction measurements from wet illite-rich fault gouge extracted from San Andreas Fault Observatory at Depth (SAFOD) phase 1 core samples and from weak minerals associated with the San Andreas Fault. Third, we reevaluate the state of stress on the San Andreas Fault in light of new constraints imposed by SAFOD borehole data. Pure talc (m0.1) had the lowest strength considered and was sufficiently weak to satisfy weak fault heat flow and stress orientation constraints with hydrostatic pore pressure. Other fault gouges showed a systematic increase in strength with increasing temperature and pressure. In this case, heat flow and stress orientation constraints would require elevated pore pressure and, in some cases, fault zone pore pressure in excess of vertical stress.

Spectral reflectance analysis of hydrothermal alteration in drill chips from two geothermal fields, Nevada

NASA Astrophysics Data System (ADS)

Lamb, A. K.; Calvin, W. M.

2010-12-01

We surveyed drill chips with a lab spectrometer in the visible-near infrared (VNIR) and short-wave infrared (SWIR) regions, 0.35-2.5 μm, to evaluate hydrothermal alteration mineralogy of samples from two known geothermal fields in western Nevada. Rock is fractured into small pieces or “chips” during drilling and stored in trays by depth interval. The drill chips are used to determine subsurface properties such as lithology, structure, and alteration. Accurately determining alteration mineralogy in the geothermal reservoir is important for indicating thermal fluids (usually associated with fluid pathways such as faults) and the highest temperature of alteration. Hydrothermal minerals, including carbonates, iron oxides, hydroxides, sheet silicates, and sulfates, are especially diagnostic in the VNIR-SWIR region.. The strength of reflectance spectroscopy is that it is rapid and accurate for differentiating temperature-sensitive minerals that are not visually unique. We examined drill chips from two western Nevada geothermal fields: Hawthorne (two wells) and Steamboat Springs (three wells) using an ASD lab spectrometer with very high resolution. The Steamboat Hills geothermal field has produced electricity since 1988 and is well studied, and is believed to be a combination of extensional tectonics and magmatic origin. Bedrocks are Cretaceous granodiorite intruding into older metasediments. Hot springs and other surface expressions occur over an area of about 2.6 km2. In contrast, the Hawthorne geothermal reservoir is a ‘blind’ system with no surface expressions such as hot springs or geysers. The geothermal field is situated in a range front fault zone in an extensional area, and is contained in Mesozoic mixed granite and meta-volcanics. We collected spectra at each interval in the chip trays. Interval length varied between 10’ and 30’. - Endmember analysis and mineral identification were performed -using standard analysis approaches used to map mineralogy in remote sensing data sets. Mapped by depth, we identified narrow zones of intense alteration that mark fluid circulation, and overall changes in metamorphic grade facies through clay type. Steamboat Hills is more highly altered than Hawthorne, thus the alteration assemblages reflect the pH and temperature differences.

Load and resistance factor design of drilled shafts in shale for lateral loading.

DOT National Transportation Integrated Search

2014-04-01

A research project involving 32 drilled shaft load tests was undertaken to establish LRFD procedures for : design of drilled shafts subjected to lateral loads. Tests were performed at two Missouri Department of : Transportation (MoDOT) geotechnical r...

The Newberry Deep Drilling Project (NDDP)

NASA Astrophysics Data System (ADS)

Bonneville, A.; Cladouhos, T. T.; Petty, S.; Schultz, A.; Sorle, C.; Asanuma, H.; Friðleifsson, G. Ó.; Jaupart, C. P.; Moran, S. C.; de Natale, G.

2017-12-01

We present the arguments to drill a deep well to the ductile/brittle transition zone (T>400°C) at Newberry Volcano, central Oregon state, U.S.A. The main research goals are related to heat and mass transfer in the crust from the point of view of natural hazards and geothermal energy: enhanced geothermal system (EGS supercritical and beyond-brittle), volcanic hazards, mechanisms of magmatic intrusions, geomechanics close to a magmatic system, calibration of geophysical imaging techniques and drilling in a high temperature environment. Drilling at Newberry will bring additional information to a very promising field of research initiated by ICDP in the Deep Drilling project in Iceland with IDDP-1 on Krafla in 2009, followed by IDDP-2 on the Reykjanes ridge in 2016, and the future Japan Beyond-Brittle project and Krafla Magma Testbed. Newberry Volcano contains one of the largest geothermal heat reservoirs in the western United States, extensively studied for the last 40 years. All the knowledge and experience collected make this an excellent choice for drilling a well that will reach high temperatures at relatively shallow depths (< 5000 m). The large conductive thermal anomaly (320°C at 3000 m depth), has already been well-characterized by extensive drilling and geophysical surveys. This will extend current knowledge from the existing 3000 m deep boreholes at the sites into and through the brittle-ductile transition approaching regions of partial melt like lateral dykes. The important scientific questions that will form the basis of a full drilling proposal, have been addressed during an International Continental Drilling Program (ICDP) workshop held in Bend, Oregon in September 2017. They will be presented and discussed as well as the strategic plan to address them.

Laboratory study of the characteristics of fault breccias in Busan area in Korea

NASA Astrophysics Data System (ADS)

Woo, I.; Um, J.

2012-12-01

The physical and mechanical characteristics of fault breccias from near the Mt. Kumjung were estimated from laboratory tests on fractured fault breccias. Mt. Kumjung is surrounded by Yangsan Fault and Dongrae Fault which are major faults traversing the southeast part of Korea in the direction of NE-SW. The undisturbed samples were obtained from boreholes drilled in this region. The microscopic analysis on the thin sections of fault breccias showed the microstructure and the porosity of breccias. The fault breccias are composed of mainly fine quartz grains, and of angular quartz grains and weathered microcline grains. This microstructure of fault breccias might be formed by the catalasis during brittle deformation processes of the fault. 20 to 40% porosity of fault breccias could play an important role in the passage of groundwater and then in the development of fault gouge in the core part of fault. The mechanical characteristics were estimated by means of uniaxial compressive strength tests on the undisturbed breccias samples. Since fault breccias are not cohesive enough to use it directly as a test specimen, the epoxy resin was utilized to fix the outer surface of core samples. The thin plastic wrap had been enveloped before the epoxy resin was applied in order that the epoxy resin could not penetrate into the core specimens. The thickness of epoxy resin was less than 1mm not to disturb the results of uniaxial compressive strength of core samples. The measured uniaxial compressive strengths are 10 to 15MPa for the only physically fractured breccias and 8 to 10 MPa for the core specimens with hydrothermally altered surface. These results can be compared with the Hoek and Brown failure criteria : 7 to 10MPa for GSI value 40 to 50 for fault breccias with fresh surface. The overall measured strength of fault breccias is less than the strength obtained empirically by Hoek and Brown failure criteria.; ;

Drilling cost-cutting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capuano, L.E. Jr.

This presentation by Louis E. Capuano, Jr., President, ThermaSource, Inc., discusses cost-cutting in the drilling phase of geothermal energy exploration and production. All aspects of a geothermal project including the drilling must be streamlined to make it viable and commercial. If production could be maximized from each well, there would be a reduction in drilling costs. This could be achieved in several ways, including big hole and multi-hole completion, directional drilling, better knowledge of the resource and where to penetrate, etc.

A magnitude gauge in modern gouge? The key case of magnetic minerals from active Chelungpu fault, Taiwan

NASA Astrophysics Data System (ADS)

Chou, Y. M.; Aubourg, C. T.; Song, S. R.; Lee, T. Q.; Yeh, E. C.

2017-12-01

During an earthquake, physical and chemical processes lead to the alteration and formation of magnetic minerals within the gouge layer in a mature fault zone. We performed rock magnetic study and X-ray tomography on 3 gouges from Taiwan Chelungpu Fault Drilling Project (TCDP), FZB1136 (fault zone at depth of 1,136 m from TCDP borehole B), FZB1194, and FZB1243. FZB1136 gouge hosts the slip zone of 1999 Chi-Chi earthquake (Mw 7.6). Magnetite and goethite are found ubiquitously in the three gouges. The peak concentration of these magnetic minerals are shifted by 1 to 2 cm. Goethite results from the circulation of hot-fluid during or soon after earthquake. Magnetite is either inherited or formed within slip zone during earthquake. The gouge FZB1136 displays the highest concentration of magnetic minerals and none of inherited magnetic minerals of the host rocks are preserved. The highest magnetite concentration is located within the 1999 slip zone. This gouge retains a single co-seismic paleomagnetic record contemporaneous of Mw 7.6 earthquake. The FZB1194 and FZB1243 gouges display contrasting pattern. Two peaks values of magnetite concentration are found in both FZB1194 and FZB1243, which suggest the location of two main seismic events. These events are elsewhere suggested by ancient paleomagnetic records of both normal and reverse polarities. The inherited nano magnetite are preserved in FZB1194 and FZB1243. These results reveal that different seismic physical/chemical alteration processes occurred among the three fault zones. In FZB1136, a strong fluid interaction is suggested resulting in destruction of nano-grains magnetite and preservation of a unique paleomagnetic record. In the two other gouges (FZB1194 and FZB1243), we suggest much less fluid interaction, leading to the preservation of inherited nano magnetite. We suggest that these different patterns are controlled by magnitude of earthquake, high magnitude (Mw 7.6) in FZB1136 and Mw < 7.6 in FZB1194 and FZB1243.

Scientific drilling projects in ancient lakes: Integrating geological and biological histories

NASA Astrophysics Data System (ADS)

Wilke, Thomas; Wagner, Bernd; Van Bocxlaer, Bert; Albrecht, Christian; Ariztegui, Daniel; Delicado, Diana; Francke, Alexander; Harzhauser, Mathias; Hauffe, Torsten; Holtvoeth, Jens; Just, Janna; Leng, Melanie J.; Levkov, Zlatko; Penkman, Kirsty; Sadori, Laura; Skinner, Alister; Stelbrink, Björn; Vogel, Hendrik; Wesselingh, Frank; Wonik, Thomas

2016-08-01

Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects.

Interaction between drilled shaft and mechanically stabilized earth (MSE) wall : project summary.

DOT National Transportation Integrated Search

2015-08-31

Drilled shafts are being constructed within the reinforced zone of mechanically stabilized earth (MSE) walls (Figure 1). The drilled shafts may be subjected to horizontal loads and push against the front of the wall. Distress of MSE wall panels has b...

Fault identification of rotor-bearing system based on ensemble empirical mode decomposition and self-zero space projection analysis

NASA Astrophysics Data System (ADS)

Jiang, Fan; Zhu, Zhencai; Li, Wei; Zhou, Gongbo; Chen, Guoan

2014-07-01

Accurately identifying faults in rotor-bearing systems by analyzing vibration signals, which are nonlinear and nonstationary, is challenging. To address this issue, a new approach based on ensemble empirical mode decomposition (EEMD) and self-zero space projection analysis is proposed in this paper. This method seeks to identify faults appearing in a rotor-bearing system using simple algebraic calculations and projection analyses. First, EEMD is applied to decompose the collected vibration signals into a set of intrinsic mode functions (IMFs) for features. Second, these extracted features under various mechanical health conditions are used to design a self-zero space matrix according to space projection analysis. Finally, the so-called projection indicators are calculated to identify the rotor-bearing system's faults with simple decision logic. Experiments are implemented to test the reliability and effectiveness of the proposed approach. The results show that this approach can accurately identify faults in rotor-bearing systems.

Mars Analog Rio Tinto Experiment (MARTE): 2003 Drilling Campaign to Search for a Subsurface Biosphere at Rio Tinto Spain

NASA Technical Reports Server (NTRS)

Stoker, Carol; Dunagan, Stephen; Stevens, Todd; Amils, Ricardo; Gomez-Elvira, Javier; Fernandez, David; Hall, James; Lynch, Kennda; Cannon, Howard; Zavaleta, Jhony

2004-01-01

The MARTE (Mars Astrobiology Research and Technology Experiment) project, an ASTEP field experiment, is exploring for a hypothesized subsurface anaerobic chemoautotrophic biosphere in the region of the Tinto River- or Rio Tinto- in southwestern Spain. It is also demonstrating technology needed to search for a subsurface biosphere on Mars. The project has three primary objectives: (1) search for and characterize subsurface life at Rio Tinto along with the physical and chemical properties and sustaining energy sources of its environment, (2) perform a high fidelity simulation of a robotic Mars drilling mission to search for life, and (3) demonstrate the drilling, sample handling, and instrument technologies relevant to searching for life on Mars. The simulation of the robotic drilling mission is guided by the results of the aseptic drilling campaign to search for life at Rio Tinto. This paper describes results of the first phase of the aseptic drilling campaign.

El Paso County Geothermal Project at Fort Bliss. Final Project Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lear, Jon; Bennett, Carlon; Lear, Dan

The El Paso County Geothermal Project at Fort Bliss was an effort to determine the scale and scope of geothermal resources previously identified on Fort Bliss’ McGregor Range in southern Otero County, New Mexico. The project was funded with a $5,000,000 grant to El Paso County from the U.S. Department of Energy (DOE) as part of the American Recovery and Reinvestment Act of 2009 and a $4,812,500 match provided by private sector partners. The project was administered through the DOE Golden Field Office to awardee El Paso County. The primary subcontractor to El Paso County and project Principal Investigator -more » Ruby Mountain Inc. (RMI) of Salt Lake City, Utah - assembled the project team consisting of Evergreen Clean Energy Management (ECEM) of Provo, Utah, and the Energy & Geoscience Institute at the University of Utah (EGI) in Salt Lake City, UT to complete the final phases of the project. The project formally began in May of 2010 and consisted of two preliminary phases of data collection and evaluation which culminated in the identification of a drilling site for a Resource Confirmation Well on McGregor Range. Well RMI 56-5 was drilled May and June 2013 to a depth of 3,030 ft. below ground level. A string of slotted 7 inch casing was set in 8.75 inch hole on bottom fill at 3,017 ft. to complete the well. The well was drilled using a technique called flooded reverse circulation, which is most common in mineral exploration. This technique produced an exceptionally large and complete cuttings record. An exciting development at the conclusion of drilling was the suspected discovery of a formation that has proven to be of exceptionally high permeability in three desalinization wells six miles to the south. Following drilling and preliminary testing and analysis, the project team has determined that the McGregor Range thermal anomaly is large and can probably support development in the tens of megawatts.« less

Block rotations, fault domains and crustal deformation in the western US

NASA Technical Reports Server (NTRS)

Nur, Amos

1990-01-01

The aim of the project was to develop a 3D model of crustal deformation by distributed fault sets and to test the model results in the field. In the first part of the project, Nur's 2D model (1986) was generalized to 3D. In Nur's model the frictional strength of rocks and faults of a domain provides a tight constraint on the amount of rotation that a fault set can undergo during block rotation. Domains of fault sets are commonly found in regions where the deformation is distributed across a region. The interaction of each fault set causes the fault bounded blocks to rotate. The work that has been done towards quantifying the rotation of fault sets in a 3D stress field is briefly summarized. In the second part of the project, field studies were carried out in Israel, Nevada and China. These studies combined both paleomagnetic and structural information necessary to test the block rotation model results. In accordance with the model, field studies demonstrate that faults and attending fault bounded blocks slip and rotate away from the direction of maximum compression when deformation is distributed across fault sets. Slip and rotation of fault sets may continue as long as the earth's crustal strength is not exceeded. More optimally oriented faults must form, for subsequent deformation to occur. Eventually the block rotation mechanism may create a complex pattern of intersecting generations of faults.

A systematic risk management approach employed on the CloudSat project

NASA Technical Reports Server (NTRS)

Basilio, R. R.; Plourde, K. S.; Lam, T.

2000-01-01

The CloudSat Project has developed a simplified approach for fault tree analysis and probabilistic risk assessment. A system-level fault tree has been constructed to identify credible fault scenarios and failure modes leading up to a potential failure to meet the nominal mission success criteria.

Recent Developments and Adaptations in Diamond Wireline Core Drilling Technology

NASA Astrophysics Data System (ADS)

Thomas, D. M.; Nielson, D. L.; Howell, B. B.; Pardey, M.

2001-05-01

Scientific drilling using diamond wireline technology is presently undergoing a significant expansion and extension of activities that has allowed us to recover geologic samples that have heretofore been technically or financially unattainable. Under the direction and management of DOSECC, a high-capacity hybrid core drilling system was designed and fabricated for the Hawaii Scientific Drilling Project (HSDP) in 1998. This system, the DOSECC Hybrid Coring System (DHCS), has the capacity to recover H-sized core from depths of more than 6 km. In 1999, the DHCS completed the first phase of the HSDP to a depth of 3100 m at a substantially lower cost per foot than any previous scientific borehole to comparable depths and, in the process, established a new depth record for recovery of H-sized wireline core. This system has been offered for use in the Unzen Scientific Drilling Project, the Chicxulub (impact crater) Scientific Drilling Project, and the Geysers Deep Geothermal Reservoir Project. More recently, DOSECC has developed a smaller barge-mounted wireline core drilling system, the GLAD800, that is capable of recovering P-sized sediment core to depths of up to 800 m. The GLAD800 has been successfully deployed on Great Salt Lake and Bear Lake in Utah and is presently being mobilized to Lake Titicaca in South America for an extensive core recovery effort there. The coring capabilities of the GLAD800 system will be available to the global lakes drilling community for acquisition of sediment cores from many of the world's deep lakes for use in calibrating and refining global climate models. Presently under development by DOSECC is a heave-compensation system that will allow us to expand the capabilities of the moderate depth coring system to allow us to collect sediment and bottom core from the shallow marine environment. The design and capabilities of these coring systems will be presented along with a discussion of their potential applications for addressing a range of earth sciences questions.

Novel Coupled Thermochronometric and Geochemical Investigation of Blind Geothermal Resources in Fault-Controlled Dilational Corners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stockli, Daniel

Geothermal plays in extensional and transtensional tectonic environments have long been a major target in the exploration of geothermal resources and the Dixie Valley area has served as a classic natural laboratory for this type of geothermal plays. In recent years, the interactions between normal faults and strike-slip faults, acting either as strain relay zones have attracted significant interest in geothermal exploration as they commonly result in fault-controlled dilational corners with enhanced fracture permeability and thus have the potential to host blind geothermal prospects. Structural ambiguity, complications in fault linkage, etc. often make the selection for geothermal exploration drilling targetsmore » complicated and risky. Though simplistic, the three main ingredients of a viable utility-grade geothermal resource are heat, fluids, and permeability. Our new geological mapping and fault kinematic analysis derived a structural model suggest a two-stage structural evolution with (a) middle Miocene N -S trending normal faults (faults cutting across the modern range), - and tiling Olio-Miocene volcanic and sedimentary sequences (similar in style to East Range and S Stillwater Range). NE-trending range-front normal faulting initiated during the Pliocene and are both truncating N-S trending normal faults and reactivating some former normal faults in a right-lateral fashion. Thus the two main fundamental differences to previous structural models are (1) N-S trending faults are pre-existing middle Miocene normal faults and (2) these faults are reactivated in a right-later fashion (NOT left-lateral) and kinematically linked to the younger NE-trending range-bounding normal faults (Pliocene in age). More importantly, this study provides the first constraints on transient fluid flow through the novel application of apatite (U-Th)/He (AHe) and 4He/ 3He thermochronometry in the geothermally active Dixie Valley area in Nevada.« less

Logs and Scarp Data from a Paloseismic Investigation of the Surprise Valley Fault Zone, Modoc County, California

USGS Publications Warehouse

Personius, Stephen F.; Crone, Anthony J.; Machette, Michael N.; Lidke, David J.; Bradley, Lee-Ann; Mahan, Shannon

2007-01-01

This report contains field and laboratory data from a paleoseismic study of the Surprise Valley fault zone near Cedarville, California. The 85-km-long Surprise Valley fault zone forms the western active margin of the Basin and Range province in northeastern California. The down-to-the-east normal fault is marked by Holocene fault scarps along most of its length, from Fort Bidwell on the north to near the southern end of Surprise Valley. We studied the central section of the fault to determine ages of paleoearthquakes and to better constrain late Quaternary slip rates, which we hope to compare to deformation rates derived from a recently established geodetic network in the region (Hammond and Thatcher, 2005; 2007). We excavated a trench in June 2005 across a prominent fault scarp on pluvial Lake Surprise deltaic sediments near the mouth of Cooks Canyon, 4 km north of Cedarville. This site was chosen because of the presence of a well-preserved fault scarp and its development on lacustrine deposits thought to be suitable for luminescence dating. We also logged a natural exposure of the fault in similar deltaic sediments near the mouth of Steamboat Canyon, 11 km south of Cedarville, to better understand the along-strike extent of surface ruptures. The purpose of this report is to present photomosaics, trench, drill hole, and stream exposure logs; scarp profiles; and fault slip, tephrochronologic, radiocarbon, luminescence, and unit description data obtained during this investigation. We do not attempt to use the data presented herein to construct a paleoseismic history of this part of the Surprise Valley fault zone; that history will be the subject of a future report.

Origin and significance of clay-coated fractures in mudrock fragments of the SAFOD borehole (Parkfield, California)

USGS Publications Warehouse

Schleicher, A.M.; van der Pluijm, B.A.; Solum, J.G.; Warr, L.N.

2006-01-01

The clay mineralogy and texture of rock fragments from the SAFOD borehole at 3067 m and 3436 m measured depth (MD) was investigated by electron microscopy (SEM, TEM) and X-ray-diffraction (XRD). The washed and ultrasonically cleaned samples show slickenfiber striations and thin films of Ca-K bearing smectite that are formed on polished fault surfaces, along freshly opened fractures and within adjacent mineralized veins. The cation composition and hydration behavior of these films differ from the Namontmorillonite of the fresh bentonite drilling mud, although there is more similarity with circulated mud recovered from 3479 m MD. We propose that these thin film smectite precipitates formed by natural nucleation and crystal growth during fault creep, probably associated with the shallow circulation of low temperature aqueous fluids along this shallow portion of the San Andreas Fault. Copyright 2006 by the American Geophysical Union.

Paleomagnetic reorientation of San Andreas Fault Observatory at Depth (SAFOD) core

USGS Publications Warehouse

Pares, J.M.; Schleicher, A.M.; van der Pluijm, B.A.; Hickman, S.

2008-01-01

We present a protocol for using paleomagnetic analysis to determine the absolute orientation of core recovered from the SAFOD borehole. Our approach is based on determining the direction of the primary remanent magnetization of a spot core recovered from the Great Valley Sequence during SAFOD Phase 2 and comparing its direction to the expected reference field direction for the Late Cretaceous in North America. Both thermal and alternating field demagnetization provide equally resolved magnetization, possibly residing in magnetite, that allow reorientation. Because compositionally similar siltstones and fine-grained sandstones were encountered in the San Andreas Fault Zone during Stage 2 rotary drilling, we expect that paleomagnetic reorientation will yield reliable core orientations for continuous core acquired from directly within and adjacent to the San Andreas Fault during SAFOD Phase 3, which will be key to interpretation of spatial properties of these rocks. Copyright 2008 by the American Geophysical Union.

Geophysical interpretations west of and within the northwestern part of the Nevada Test Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grauch, V.J.; Sawyer, D.A.; Fridrich, C.J.

1997-12-31

This report focuses on interpretation of gravity and new magnetic data west of the Nevada Test Site (NTS) and within the northwestern part of NTS. The interpretations integrate the gravity and magnetic data with other geophysical, geological, and rock property data to put constraints on tectonic and magmatic features not exposed at the surface. West of NTS, where drill hole information is absent, these geophysical data provide the best available information on the subsurface. Interpreted subsurface features include calderas, intrusions, basalt flows and volcanoes, Tertiary basins, structurally high pre-Tertiary rocks, and fault zones. New features revealed by this study includemore » (1) a north-south buried tectonic fault east of Oasis Mountain, which the authors call the Hogback fault; (2) an east striking fault or accommodation zone along the south side of Oasis Valley basin, which they call the Hot Springs fault; (3) a NNE striking structural zone coinciding with the western margins of the caldera complexes; (4) regional magnetic highs that probably represent a thick sequence of Tertiary volcanic rocks; and (5) two probable buried calderas that may be related to the tuffs of Tolicha Peak and of Sleeping Butte, respectively.« less

NanTroSEIZE observatories: Installation of a long-term borehole monitoring systems offshore the Kii Peninsula, Japan

NASA Astrophysics Data System (ADS)

Kopf, A.; Saffer, D. M.; Davis, E. E.; Araki, E.; Kinoshita, M.; Lauer, R. M.; Wheat, C. G.; Kitada, K.; Kimura, T.; Toczko, S.; Eguchi, N. O.; Science Parties, E.

2010-12-01

The IODP Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a multi-expedition drilling program designed to investigate fault mechanics, fault slip behavior, and strain accumulation along subduction megathrusts, through coring, logging, and long-term monitoring experiments. One key objective is the development and installation of a borehole observatory network extending from locations above the outer, presumably aseismic accretionary wedge to the seismogenic and interseismically locked plate interface, to record seismicity and slip transients, monitor strain accumulation, document hydraulic transients associated with deformation events, and quantify in situ pore fluid pressure and temperature. As part of recent NanTroSEIZE operations, borehole instruments have been developed for deployment at two sites: (1) Site C0010, which penetrates a major out-of-sequence thrust fault termed the “megasplay” at ca. 400 mbsf, and (2) Site C0002 in the Kumano forearc basin at a location that overlies both the updip edge of the inferred interseismically locked portion of the plate interface, and clusters of very low frequency thrust and reverse earthquakes located within the accretionary prism and potentially on the megasplay fault. In 2009, Site C0010 was drilled and cased with screens to access the megasplay fault, and a simple pore pressure and temperature monitoring system (a ”smartplug”) was installed. The simple observatory unit includes pressure and temperature sensors and a data logging package mounted beneath a mechanically set retrievable casing packer, and includes two pressure sensors, one in hydraulic communication with the formation through the casing screens below the packer, and the other to the open borehole above the packer to record hydrostatic reference pressure and ocean loading signals. Temperatures are recorded within the instrument package using a platinum thermometer and by a self-contained miniature temperature logger (MTL). In fall 2010, the smartplug will be retrieved and replaced with an upgraded instrument package that also includes an autonomous osmotic geochemical sampling system and microbial colonization experiment. Fall 2010 operations will also drill and case Site C0002 to ca. 1000 m depth and install a newly developed multi-sensor permanent observatory system, which includes a volumetric strainmeter, a broadband seismometer, tiltmeter, thermister string, and multi-level pore-pressure sensors. The strain, seismometer, and tilt sensors will be cemented with the basal mudstones of the Kumano basin, and pore pressure will be monitored within both the underlying accretionary prism and within the lower basin sediments. The observatory will ultimately be connected to the seafloor fiber-optic cable network DONET. Here, we report on the retrieval of the smartplug, installation and configuration of the new multi-sensor permanent observatory, and preliminary data obtained from the smartplug deployment.

Laser Drilling Development Trial Final Report CRADA No. TSB-1538-98

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hermann, M. R.; Hebbar, R. R.

This project performed various laser drilling tests to demonstrate femtosecond laser drilling of fuel injector nozzles with minimal recast, minimal heat affected zone and no collateral damage. LLNL had extensive experience in ultra short-pulse laser systems and developed specialized hardware for these applications.

Investigations related to scientific deep drilling to study reservoir-triggered earthquakes at Koyna, India

NASA Astrophysics Data System (ADS)

Gupta, Harsh; Purnachandra Rao, N.; Roy, Sukanta; Arora, Kusumita; Tiwari, V. M.; Patro, Prasanta K.; Satyanarayana, H. V. S.; Shashidhar, D.; Mallika, K.; Akkiraju, Vyasulu V.; Goswami, Deepjyoti; Vyas, Digant; Ravi, G.; Srinivas, K. N. S. S. S.; Srihari, M.; Mishra, S.; Dubey, C. P.; Raju, D. Ch. V.; Borah, Ujjal; Chinna Reddy, K.; Babu, Narendra; Rohilla, Sunil; Dhar, Upasana; Sen, Mrinal; Bhaskar Rao, Y. J.; Bansal, B. K.; Nayak, Shailesh

2015-09-01

Artificial water reservoir-triggered earthquakes have continued at Koyna in the Deccan Traps province, India, since the impoundment of the Shivaji Sagar reservoir in 1962. Existing models, to comprehend the genesis of triggered earthquakes, suffer from lack of observations in the near field. To investigate further, scientific deep drilling and setting up a fault zone observatory at depth of 5-7 km is planned in the Koyna area. Prior to undertaking deep drilling, an exploratory phase of investigations has been launched to constrain subsurface geology, structure and heat flow regime in the area that provide critical inputs for the design of the deep borehole observatory. Two core boreholes drilled to depths of 1,522 and 1,196 m have penetrated the Deccan Traps and sampled the granitic basement in the region for the first time. Studies on cores provide new and direct information regarding the thickness of the Deccan Traps, the absence of infra-Trappean sediments and the nature of the underlying basement rocks. Temperatures estimated at a depth of 6 km in the area, made on the basis of heat flow and thermal properties data sets, do not exceed 150 °C. Low-elevation airborne gravity gradient and magnetic data sets covering 5,012 line km, together with high-quality magnetotelluric data at 100 stations, provide both regional information about the thickness of the Deccan Traps and the occurrence of localized density heterogeneities and anomalous conductive zones in the vicinity of the hypocentral zone. Acquisition of airborne LiDAR data to obtain a high-resolution topographic model of the region has been completed over an area of 1,064 km2 centred on the Koyna seismic zone. Seismometers have been deployed in the granitic basement inside two boreholes and are planned in another set of six boreholes to obtain accurate hypocentral locations and constrain the disposition of fault zones.

Drilling into an active mofette: pilot-hole study of the impact of CO2-rich mantle-derived fluids on the geo-bio interaction in the western Eger Rift (Czech Republic)

NASA Astrophysics Data System (ADS)

Bussert, Robert; Kämpf, Horst; Flechsig, Christina; Hesse, Katja; Nickschick, Tobias; Liu, Qi; Umlauft, Josefine; Vylita, Tomáš; Wagner, Dirk; Wonik, Thomas; Estrella Flores, Hortencia; Alawi, Mashal

2017-11-01

Microbial life in the continental deep biosphere is closely linked to geodynamic processes, yet this interaction is poorly studied. The Cheb Basin in the western Eger Rift (Czech Republic) is an ideal place for such a study because it displays almost permanent seismic activity along active faults with earthquake swarms up to ML 4.5 and intense degassing of mantle-derived CO2 in conduits that show up at the surface in form of mofettes. We hypothesize that microbial life is significantly accelerated in active fault zones and in CO2 conduits, due to increased fluid and substrate flow. To test this hypothesis, pilot hole HJB-1 was drilled in spring 2016 at the major mofette of the Hartoušov mofette field, after extensive pre-drill surveys to optimize the well location. After drilling through a thin caprock-like structure at 78.5 m, a CO2 blowout occurred indicating a CO2 reservoir in the underlying sandy clay. A pumping test revealed the presence of mineral water dominated by Na+, Ca2+, HCO3-, SO42- (Na-Ca-HCO3-SO4 type) having a temperature of 18.6 °C and a conductivity of 6760 µS cm-1. The high content of sulfate (1470 mg L-1) is typical of Carlsbad Spa mineral waters. The hole penetrated about 90 m of Cenozoic sediments and reached a final depth of 108.50 m in Palaeozoic schists. Core recovery was about 85 %. The cored sediments are mudstones with minor carbonates, sandstones and lignite coals that were deposited in a lacustrine environment. Deformation structures and alteration features are abundant in the core. Ongoing studies will show if they result from the flow of CO2-rich fluids or not.

Earthquake-driven fluid flow rates inferred from borehole temperature measurements within the Japan Trench plate boundary fault zone

NASA Astrophysics Data System (ADS)

Fulton, P. M.; Brodsky, E. E.

2016-12-01

Using borehole sub-seafloor temperature measurements, we have recently identified signatures suggestive of earthquake-driven fluid pulses within the Japan Trench plate boundary fault zone during a major aftershock sequence. Here we use numerical models to show that these signatures are consistent with time-varying fluid flow rates out of permeable zones within the formation into the borehole annulus. In addition, we also identify an apparent time-varying sensitivity of whether suspected fluid pulses occur in response to earthquakes of a given magnitude and distance. The results suggest a damage and healing process and therefore provides a mechanism to allow for a disproportionate amount of heat and chemical transport in the short time frame after an earthquake. Our observations come from an observatory installed across the main plate boundary fault as part of IODP's Japan Trench Fast Drilling Project (JFAST) following the March 2011 Mw 9.0 Tohoku-oki earthquake. It operated from July 2012 - April 2013 during which a Mw 7.3 earthquake and numerous aftershocks occurred. High-resolution temperature time series data reveal spatially correlated transients in response to earthquakes with distinct patterns interpreted to reflect advection by transient pulses of fluid flow from permeable zones into the borehole annulus. Typical transients involve perturbations over 12 m with increases of 10 mK that build over 0.1 days at shallower depths and decreases at deeper depths. They are consistently centered around 792.5 m below seafloor (mbsf) where a secondary fault and permeable zone have been independently identified within the damage zone above the main plate boundary fault at 820 mbsf . Model simulations suggest transient flow rates of up to 10-3m/s from the formation that quickly decrease. Comparison of characteristics of earthquakes identified in nearby ocean bottom pressure measurements suggest there is not a clear relationship between fluid pulses and static strain. There does appear to be a time-varying sensitivity likely from dynamic stresses suggestive of a damage process followed by healing over 1 month time. The transient redistribution of fluid pressures and fluid flow within fault zones inferred here is a potential mechanism for earthquake triggering and episodic heat and chemical transport.

Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

NASA Astrophysics Data System (ADS)

Nedorub, O. I.; Knapp, C. C.

2012-12-01

The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill-hole and seismic data along the Augusta profile show that there is a significant offset (approximately 7m) down to the SE of Pinehurst and older Cretaceous deposits. The Pen Branch fault seismic profile shows evidence of Cenozoic reactivation and inversion. The youngest discontinuous reflector (the top of the Dry Branch Formation) is offset by 1-4m and constrains the latest fault movement to be Middle Eocene in age. A NW-SE well derived cross-section across the Allendale fault shows that there is no significant offset above 50m below sea level (top of the Late Eocene Black Mingo Group), however a SW-NE cross section shows an approximately 21m offset NE side up across the newly postulated fault striking NW-SE. The top of the oldest undeformed formation (Middle Eocene Santee Limestone) and the top of the youngest deformed unit (Late Eocene Black Mingo Group) constrain a time frame for the latest deformation of the Coastal Plain sediments to be between approximately 50 and 40 Ma. The results of this research provide an opportunity to address the Cenozoic tectonism in SC, advance the knowledge and current understanding of the structure of the rift basins, update the database used for the ongoing CO2 sequestration project, the local hydrology, and the Savannah River Site safety evaluation.

Drill hole data for coal beds in the Powder River Basin, Montana and Wyoming

USGS Publications Warehouse

Haacke, Jon E.; Scott, David C.

2013-01-01

This report by the U.S. Geological Survey (USGS) of the Powder River Basin (PRB) of Montana and Wyoming is part of the U.S. Coal Resources and Reserves Assessment Project. Essential to that project was the creation of a comprehensive drill hole database that was used for coal bed correlation and for coal resource and reserve assessments in the PRB. This drill hole database was assembled using data from the USGS National Coal Resources Data System, several other Federal and State agencies, and selected mining companies. Additionally, USGS personnel manually entered lithologic picks into the database from geophysical logs of coalbed methane, oil, and gas wells. Of the 29,928 drill holes processed, records of 21,393 are in the public domain and are included in this report. The database contains location information, lithology, and coal bed names for each drill hole.

Dead Sea deep cores: A window into past climate and seismicity

NASA Astrophysics Data System (ADS)

Stein, Mordechai; Ben-Avraham, Zvi; Goldstein, Steven L.

2011-12-01

The area surrounding the Dead Sea was the locus of humankind's migration out of Africa and thus has been the home of peoples since the Stone Age. For this reason, understanding the climate and tectonic history of the region provides valuable insight into archaeology and studies of human history and helps to gain a better picture of future climate and tectonic scenarios. The deposits at the bottom of the Dead Sea are a geological archive of the environmental conditions (e.g., rains, floods, dust storms, droughts) during ice ages and warm ages, as well as of seismic activity in this key region. An International Continental Scientific Drilling Program (ICDP) deep drilling project was performed in the Dead Sea between November 2010 and March 2011. The project was funded by the ICDP and agencies in Israel, Germany, Japan, Norway, Switzerland, and the United States. Drilling was conducted using the new Large Lake Drilling Facility (Figure 1), a barge with a drilling rig run by DOSECC, Inc. (Drilling, Observation and Sampling of the Earth's Continental Crust), a nonprofit corporation dedicated to advancing scientific drilling worldwide. The main purpose of the project was to recover a long, continuous core to provide a high resolution record of the paleoclimate, paleoenvironment, paleoseismicity, and paleomagnetism of the Dead Sea Basin. With this, scientists are beginning to piece together a record of the climate and seismic history of the Middle East during the past several hundred thousand years in millennial to decadal to annual time resolution.

Map and database of Quaternary faults and folds in Colombia and its offshore regions

USGS Publications Warehouse

Paris, Gabriel; Machette, Michael N.; Dart, Richard L.; Haller, Kathleen M.

2000-01-01

As part of the International Lithosphere Program’s “World Map of Major Active Faults,” the U.S. Geological Survey (USGS) is assisting in the compilation of a series of digital maps of Quaternary faults and folds in Western Hemisphere countries. The maps show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. They are accompanied by databases that describe these features and document current information on their activity in the Quaternary. Top date, the project has published fault and fold maps for Costa Rica (Montero and others, 1998), Panama (Cowan and others, 1998), Venezuela (Audemard and others, 2000), Bolovia/Chile (Lavenu, and others, 2000), and Argentina (Costa and others, 2000). The project is a key part of the Global Seismic Hazards Assessment Program (ILP Project II-0) for the International Decade for Natural Hazard Disaster Reduction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upchurch, J.L.

In order to better meet the challenges associated with downsizing and because of the ongoing need to control costs and accelerate project development many companies are trying new and different strategies in managing projects. For the Seastar Project, Phillips adopted a total team approach. The goal of this approach was to develop a win/win attitude for all of the personnel (Phillips, Engineering Contractor and Equipment Vendors) involved in the project. By bringing all the personnel together and focusing on project success it was thought that costs could be better controlled and that the development schedule could be accelerated. The Seastarmore » Project is a two well subsea development located in Garden Banks Blocks 70 and 71 approximately 120 miles south of Cameron Louisiana. Phillips took over operatorship in 1992 and drilled Garden Banks Block 71 No. 2, which discovered 349 feet of net gas pay in April 1993. Following a successful drill stem test on GB 71 No. 2, drilling was started on an appraisal well and work began on a feasibility study to define development options.« less

Condensed listing of surface boreholes at the Waste Isolation Pilot Plant Project through 31 December 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, L.R.; Aguilar, R.; Mercer, J.W.

This report contains a condensed listing of Waste Isolation Pilot Plant (WIPP) project surface boreholes drilled for the purpose of site selection and characterization through 31 December 1995. The US Department of Energy (DOE) sponsored the drilling activities, which were conducted primarily by Sandia National Laboratories. The listing provides physical attributes such as location (township, range, section, and state-plane coordinates), elevation, and total borehole depth, as well as the purpose for the borehole, drilling dates, and information about extracted cores. The report also presents the hole status (plugged, testing, monitoring, etc.) and includes salient findings and references. Maps with boreholemore » locations and times-of-drilling charts are included.« less

Correlation between deep fluids, tremor and creep along the central San Andreas fault

USGS Publications Warehouse

Becken, M.; Ritter, O.; Bedrosian, P.A.; Weckmann, U.

2011-01-01

The seismicity pattern along the San Andreas fault near Parkfield and Cholame, California, varies distinctly over a length of only fifty kilometres. Within the brittle crust, the presence of frictionally weak minerals, fault-weakening high fluid pressures and chemical weakening are considered possible causes of an anomalously weak fault northwest of Parkfield. Non-volcanic tremor from lower-crustal and upper-mantle depths is most pronounced about thirty kilometres southeast of Parkfield and is thought to be associated with high pore-fluid pressures at depth. Here we present geophysical evidence of fluids migrating into the creeping section of the San Andreas fault that seem to originate in the region of the uppermost mantle that also stimulates tremor, and evidence that along-strike variations in tremor activity and amplitude are related to strength variations in the lower crust and upper mantle. Interconnected fluids can explain a deep zone of anomalously low electrical resistivity that has been imaged by magnetotelluric data southwest of the Parkfield-Cholame segment. Near Cholame, where fluids seem to be trapped below a high-resistivity cap, tremor concentrates adjacent to the inferred fluids within a mechanically strong zone of high resistivity. By contrast, subvertical zones of low resistivity breach the entire crust near the drill hole of the San Andreas Fault Observatory at Depth, northwest of Parkfield, and imply pathways for deep fluids into the eastern fault block, coincident with a mechanically weak crust and the lower tremor amplitudes in the lower crust. Fluid influx to the fault system is consistent with hypotheses of fault-weakening high fluid pressures in the brittle crust.

The regional structural setting of the 2008 Wells earthquake and Town Creek Flat Basin: implications for the Wells earthquake fault and adjacent structures

USGS Publications Warehouse

Henry, Christopher S.; Colgan, Joseph P.

2011-01-01

The 2008 Wells earthquake occurred on a northeast-striking, southeast-dipping fault that is clearly delineated by the aftershock swarm to a depth of 10-12 km below sea level. However, Cenozoic rocks and structures around Wells primarily record east-west extension along north- to north-northeast-striking, west-dipping normal faults that formed during the middle Miocene. These faults are responsible for the strong eastward tilt of most basins and ranges in the area, including the Town Creek Flat basin (the location of the earthquake) and the adjacent Snake Mountains and western Windermere Hills. These older west-dipping faults are locally overprinted by a younger generation of east-dipping, high-angle normal faults that formed as early as the late Miocene and have remained active into the Quaternary. The most prominent of these east-dipping faults is the set of en-échelon, north-striking faults that bounds the east sides of the Ruby Mountains, East Humboldt Range, and Clover Hill (about 5 km southwest of Wells). The northeastern-most of these faults, the Clover Hill fault, projects northward along strike toward the Snake Mountains and the approximately located surface projection of the Wells earthquake fault as defined by aftershock locations. The Clover Hill fault also projects toward a previously unrecognized, east-facing Quaternary fault scarp and line of springs that appear to mark a significant east-dipping normal fault along the western edge of Town Creek Flat. Both western and eastern projections may be northern continuations of the Clover Hill fault. The Wells earthquake occurred along this east-dipping fault system. Two possible alternatives to rupture of a northern continuation of the Clover Hill fault are that the earthquake fault (1) is antithetic to an active west-dipping fault or (2) reactivated a Mesozoic thrust fault that dips east as a result of tilting by the west-dipping faults along the west side of the Snake Mountains. Both alternatives are precluded by the depths of the earthquake and aftershocks, about 8 km and as deep as 12 km, respectively. These depths are below where an antithetic fault would intersect any main fault, and a tilted, formerly shallow and sub-horizontal thrust fault would not extend to depths of more than about 5–6 km. The east-dipping, high-angle, earthquake fault cuts older west-dipping faults rather than reactivating them, highlighting a change in the structural style of Basin and Range extension in this region from closely-spaced, west-dipping faults that rotated significantly during slip and accommodated large-magnitude extension, to widely-spaced, high-angle faults that accommodate much less total strain over a long time span.

Systematic assessment of fault stability in the Northern Niger Delta Basin, Nigeria: Implication for hydrocarbon prospects and increased seismicities

NASA Astrophysics Data System (ADS)

Adewole, E. O.; Healy, D.

2017-03-01

Accurate information on fault networks, the full stress tensor, and pore fluid pressures are required for quantifying the stability of structure-bound hydrocarbon prospects, carbon dioxide sequestration, and drilling prolific and safe wells, particularly fluid injections wells. Such information also provides essential data for a proper understanding of superinduced seismicities associated with areas of intensive hydrocarbon exploration and solid minerals mining activities. Pressure and stress data constrained from wells and seismic data in the Northern Niger Delta Basin (NNDB), Nigeria, have been analysed in the framework of fault stability indices by varying the maximum horizontal stress direction from 0° to 90°, evaluated at depths of 2 km, 3.5 km and 4 km. We have used fault dips and azimuths interpreted from high resolution 3D seismic data to calculate the predisposition of faults to failures in three faulting regimes (normal, pseudo-strike-slip and pseudo-thrust). The weighty decrease in the fault stability at 3.5 km depth from 1.2 MPa to 0.55 MPa demonstrates a reduction of the fault strength by high magnitude overpressures. Pore fluid pressures > 50 MPa have tendencies to increase the risk of faults to failure in the study area. Statistical analysis of stability indices (SI) indicates faults dipping 50°-60°, 80°-90°, and azimuths ranging 100°-110° are most favourably oriented for failure to take place, and thus likely to favour migrations of fluids given appropriate pressure and stress conditions in the dominant normal faulting regime of the NNDB. A few of the locally assessed stability of faults show varying results across faulting regimes. However, the near similarities of some model-based results in the faulting regimes explain the stability of subsurface structures are greatly influenced by the maximum horizontal stress (SHmax) direction and magnitude of pore fluid pressures.

New Era of Scientific Ocean Drilling

NASA Astrophysics Data System (ADS)

Eguchi, N.; Toczko, S.; Sanada, Y.; Igarashi, C.; Kubo, Y.; Maeda, L.; Sawada, I.; Takase, K.; Kyo, N.

2014-12-01

The D/V Chikyu, committed to scientific ocean drilling since 2007, has completed thirteen IODP expeditions, and Chikyu's enhanced drilling technology gives us the means to reach deep targets, enhanced well logging, deep water riserless drilling, and state of the art laboratory. Chikyu recovered core samples from 2466 meters below sea floor (mbsf) in IODP Exp. 337, and drilled to 3058.5 mbsf in IODP Exp. 348, but these are still not the limit of Chikyu's capability. As deep as these depths are, they are just halfway to the 5200 mbsf plate boundary target for the NanTroSEIZE deep riser borehole. There are several active IODP proposals in the pipeline. Each has scientific targets requiring several thousand meters of penetration below the sea floor. Riser technology is the only way to collect samples and data from that depth. Well logging has been enhanced with the adoption of riser drilling, especially for logging-while-drilling (LWD). LWD has several advantages over wireline logging, and provides more opportunities for continuous measurements even in unstable boreholes. Because of the larger diameter of riser pipes and enhanced borehole stability, Chikyu can use several state-of-the-art downhole tools, e.g. fracture tester, fluid sampling tool, wider borehole imaging, and the latest sonic tools. These new technologies and tools can potentially expand the envelope of scientific ocean drilling. Chikyu gives us access to ultra-deep water riserless drilling. IODP Exp. 343/343T investigating the March 2011 Tohoku Oki Earthquake, explored the toe of the landward slope of the Japan Trench. This expedition reached the plate boundary fault target at more than 800 mbsf in water depths over 6900 m for logging-while-drilling, coring, and observatory installation. This deep-water drilling capability also expands the scientific ocean drilling envelope and provides access to previously unreachable targets. On top of these operational capabilities, Chikyu's onboard laboratory is equipped with state-of-the-art instruments to analyze all science samples. X-ray CT creates non-destructive 3D images of core samples providing high resolution structural detail. The microbiology laboratory offers clean and contamination-free work environments required for microbiological samples.

Horizontal drilling in the Austin Chalk: Stratigraphic factors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durham, C.O. Jr.; Bobigian, R.A.

1990-05-01

Horizontal drilling has renewed interest in the Austin chalk in south-central Texas. Large fields on opposite sides of the San Marcos arch Giddings to the northeast and Pearsall to the southwest were active with vertical drilling 10 years ago. Giddings' 4,500 Austin wells produced 209 million BO and 934 bcfg of gas through 1988; Pearsall's 1,440 wells produced 57 million BO and 35 bcfg of gas. Most vertical wells were completed, 20% were economic successes, 40% were marginal, 40% were uneconomic due to uneven areal distribution of near-vertical fractures and small faults, which provide reservoirs in otherwise tight chalk. Horizontalmore » drilling, led by Amoco in Giddings and Oryx in Pearsall, enhances the chances of encountering the fractures by drilling perpendicular to the fracture trend. Horizontal drilling requires preselection of the stratigraphic horizon to be penetrated. One must understand the variable Austin stratigraphy to choose the zone with the most brittle character and best matrix porosity, both reduced by increased clay content. Chalk 130 ft thick on the San Marcos arch thickens to 600 to 800 ft in central Giddings field where middle marl separates lower and upper chalk Northeastward only lower chalk is preserved beneath a post-Austin submarine channel. The Austin thickens to 300-500 ft in Pearsall field where middle member ash beds separate lower and upper chalk inhibiting vertical reservoir communication. Locally, on the Pearsall arch, ash is missing, lower chalk thickens, and upper chalk thins.« less

The 1997 core drilling through Ordovician and Silurian strata at Röstånga, S. Sweden: preliminary stratigraphic assessment and regional comparison

USGS Publications Warehouse

Bergstrom, Stig M.; Huff, W.D.; Koren', T.; Larsson, K.; Ahlberg, P.; Kolata, Dennis R.

1999-01-01

A core drilling at Ro??sta??nga, the first such drilling ever undertaken in this classical Lower Paleozoic outcrop area in W-central Scania, penetrated an approximately 96 m thick succession of Lower Silurian-upper Middle Ordovician marine rocks. The drilling was stopped at a depth of 132.59 m in an interval of crushed rocks, probably a prominent fault zone, that proved impossible to drill through. The core contains a stratigraphical sequence from the basal Upper Llandoverian (Telychian Stage) to the upper Middle Ordovician (Harjuan Stage). The following units are recognized in descending stratigraphic order (approximate thickness in parenthesis): Kallholn Formation (35 m), Lindega??rd Mudstone (27 m), Fja??cka Shale (13 m), Mossen Formation (0.75 m), Skagen Formation (2.5 m), and Sularp Shale (19 m+). Except for the Skagen Formation, the drilled sequence consists of shales and mudstones with occasional thin limestone interbeds and is similar to coeval successions elsewhere in Scania. There are 11 K-bentonite beds in the Kallholn Formation, 2(3?) in the Lindega??rd Mudstone, 1 in the Mossen Formation, 7 in the Skagen Formation, and 33 in the Sularp Shale. The core serves as an excellent Lower Silurian-upper Middle Ordovician reference standard not only for the Ro??sta??nga area but also for southernmost Sweden in general because the cored sequence is the stratigraphically most complete one known anywhere in this region.

Assessing Past Fracture Connectivity in Geothermal Reservoirs Using Clumped Isotopes: Proof of Concept in the Blue Mountain Geothermal Field, Nevada USA

NASA Astrophysics Data System (ADS)

Huntington, K. W.; Sumner, K. K.; Camp, E. R.; Cladouhos, T. T.; Uddenberg, M.; Swyer, M.; Garrison, G. H.

2015-12-01

Subsurface fluid flow is strongly influenced by faults and fractures, yet the transmissivity of faults and fractures changes through time due to deformation and cement precipitation, making flow paths difficult to predict. Here we assess past fracture connectivity in an active hydrothermal system in the Basin and Range, Nevada, USA, using clumped isotope geochemistry and cold cathodoluminescence (CL) analysis of fracture filling cements from the Blue Mountain geothermal field. Calcite cements were sampled from drill cuttings and two cores at varying distances from faults. CL microscopy of some of the cements shows banding parallel to the fracture walls as well as brecciation, indicating that the cements record variations in the composition and source of fluids that moved through the fractures as they opened episodically. CL microscopy, δ13C and δ18O values were used to screen homogeneous samples for clumped isotope analysis. Clumped isotope thermometry of most samples indicates paleofluid temperatures of around 150°C, with several wells peaking at above 200°C. We suggest that the consistency of these temperatures is related to upwelling of fluids in the convective hydrothermal system, and interpret the similarity of the clumped isotope temperatures to modern geothermal fluid temperatures of ~160-180°C as evidence that average reservoir temperatures have changed little since precipitation of the calcite cements. In contrast, two samples, one of which was associated with fault gauge observed in drill logs, record significantly cooler temperatures of 19 and 73°C and anomalous δ13C and δ18Owater values, which point to fault-controlled pathways for downwelling meteoric fluid. Finally, we interpret correspondence of paleofluid temperatures and δ18Owater values constrained by clumped isotope thermometry of calcite from different wells to suggest past connectivity of fractures among wells within the geothermal field. Results show the ability of clumped isotope geothermometry to assess fracture connectivity and geothermal reservoir characteristics in the past—with the potential to help optimize resource production and injection programs and better understand structural controls on mass and heat transfer in the subsurface.

Geologic framework of the 2005 Keathley Canyon gas hydrate research well, northern Gulf of Mexico

USGS Publications Warehouse

Hutchinson, D.R.; Hart, P.E.; Collett, T.S.; Edwards, K.M.; Twichell, D.C.; Snyder, F.

2008-01-01

The Keathley Canyon sites drilled in 2005 by the Chevron Joint Industry Project are located along the southeastern edge of an intraslope minibasin (Casey basin) in the northern Gulf of Mexico at 1335 m water depth. Around the drill sites, a grid of 2D high-resolution multichannel seismic data designed to image depths down to at least 1000 m sub-bottom reveals 7 unconformities and disconformities that, with the seafloor, bound 7 identifiable seismic stratigraphic units. A major disconformity in the middle of the units stands out for its angular baselapping geometry. From these data, three episodes of sedimentary deposition and deformation are inferred. The oldest episode consists of fine-grained muds deposited during a period of relative stability in the basin (units e, f, and g). Both the BSR and inferred gas hydrate occur within these older units. The gas hydrate occurs in near-vertical fractures. A second episode (units c and d) involved large vertical displacements associated with infilling and ponding of sediment. This second interval corresponds to deposition of intercalated fine and coarse-grained material that was recovered in the drill hole that penetrated the thin edges of the regionally much thicker units. The final episode of deposition (units a and b) occurred during more subdued vertical motions. Hemipelagic drape (unit a) characterizes the modern seafloor. The present-day Casey basin is mostly filled. Its sill is part of a subsiding graben structure that is only 10-20 m shallower than the deepest point in the basin, indicating that gravity-driven transport would mostly bypass the basin. Contemporary faulting along the basin margins has selectively reactivated an older group of faults. The intercalated sand and mud deposits of units c and d are tentatively correlated with Late Pleistocene deposition derived from the western shelf-edge delta/depocenter of the Mississippi River, which was probably most active from 320 ka to 70 ka [Winker, C.D., Booth, J., 2000. Sedimentary dynamics of the salt-dominated continental slope, Gulf of Mexico: integration of observations from the seafloor, near-surface, and deep subsurface. In: Proceedings of the GCSSEPM Foundation 20th Annual Research Conference, Deep-water Reservoirs of the World, pp. 1059-1086]. The presence of sand within the gas hydrate stability zone (in units c and d) is not sufficient to concentrate gas hydrate even though dispersed gas hydrate occurs deeper in the fractured mud/clay-rich sections of units e and f.

Investigating the soil removal characteristics of flexible tube coring method for lunar exploration

NASA Astrophysics Data System (ADS)

Tang, Junyue; Quan, Qiquan; Jiang, Shengyuan; Liang, Jieneng; Lu, Xiangyong; Yuan, Fengpei

2018-02-01

Compared with other technical solutions, sampling the planetary soil and returning it back to Earth may be the most direct method to seek the evidence of extraterrestrial life. To keep sample's stratification for further analyzing, a novel sampling method called flexible tube coring has been adopted for China future lunar explorations. Given the uncertain physical properties of lunar regolith, proper drilling parameters should be adjusted immediately in piercing process. Otherwise, only a small amount of core could be sampled and overload drilling faults could occur correspondingly. Due to the fact that the removed soil is inevitably connected with the cored soil, soil removal characteristics may have a great influence on both drilling loads and coring results. To comprehend the soil removal characteristics, a non-contact measurement was proposed and verified to acquire the coring and removal results accurately. Herein, further more experiments in one homogenous lunar regolith simulant were conducted, revealing that there exists a sudden core failure during the sampling process and the final coring results are determined by the penetration per revolution index. Due to the core failure, both drilling loads and soil's removal states are also affected thereby.

Constraints and inferences of conditions of seismic slip from analyses of exhumed faults

NASA Astrophysics Data System (ADS)

Evans, J. P.

2008-12-01

The study of exhumed faults, where constrained by geochemical or geochronologic evidence for depth of deformation, has provided abundant insights into the processes by which the upper crust accommodates strain. What remains elusive in these studies are: a] what evidence do we have for diagnosing [paleo] seismic slip, b ] how do we extrapolate the textures and composition of formerly active faults to constraining the conditions at depth, c] determining the conditions that promote seismic vs. aseismic slip, and d] to what degree do interseismic [healing] and post-slip processes exhumation affect what we see at the surface. Field evidence for the conditions that promote or are of diagnostic seismic vs. aseismic slip, is elusive, as there are few ways to determine seismic rates of slip in faults other than the presence of pseudotachylytes. Recent work on these rocks in a variety of settings and the increase in recognition of the presence of fault- related melts document the relationships between pseudotachylytes and cataclastically deformed rocks in what is thought to be the frictional regime, or with ductily deformed rocks at the base of a fault. Conditions that appear to promote seismic slip are alteration of granitic host rock to lower melting temperature phases and the presence of geometric complexities that may act as stress risers in the faults. Drilling into portions of faults where earthquakes occur at the top of the seismogenic zone have sampled fault-related rocks that have striking similarities to exhumed faults, exhibiting narrow slip surfaces, foliated cataclasites, injected gouge textures, polished slip surfaces, and thermally altered rocks along slip surfaces. We review the recent work from a wide range of studies to suggest that relatively small changes in conditions may initiate seismic slip, and suggest further avenues of investigation.

Faults in parts of north-central and western Houston metropolitan area, Texas

USGS Publications Warehouse

Verbeek, Earl R.; Ratzlaff, Karl W.; Clanton, Uel S.

1979-01-01

Hundreds of residential, commercial, and industrial structures in the Houston metropolitan area have sustained moderate to severe damage owing to their locations on or near active faults. Paved roads have been offset by faults at hundreds of locations, butted pipelines have been distorted by fault movements, and fault-induced gradient changes in drainage lines have raised concern among flood control engineers. Over 150 faults, many of them moving at rates of 0.5 to 2 cm/yr, have been mapped in the Houston area; the number of faults probably far exceeds this figure.This report includes a map of eight faults, in north-central and western Houston, at a scale useful for land-use planning. Seven of the faults, are known, to be active and have caused considerable damage to structures built on or near them. If the eighth fault is active, it may be of concern to new developments on the west side of Houston. A ninth feature shown on the map is regarded only as a possible fault, as an origin by faulting has not been firmly established.Seismic and drill-hold data for some 40 faults, studied in detail by various investigators have verified connections between scarps at the land surface and growth faults in the shallow subsurface. Some scarps, then, are known to be the surface manifestations of faults that have geologically long histories of movement. The degree to which natural geologic processes contribute to current fault movement, however, is unclear, for some of man’s activities may play a role in faulting as well.Evidence that current rates of fault movement far exceed average prehistoric rates and that most offset of the land surface in the Houston area has occurred only within the last 50 years indirectly suggest that fluid withdrawal may be accelerating or reinitiating movement on pre-existing faults. This conclusion, however, is based only on a coincidence in time between increased fault activity and increased rates of withdrawal of water, oil, and gas from subsurface sediments; no cause-and-effect relationship has been demonstrated. An alternative hypothesis is that natural fault movements are characterized by short—term episodicity and that Houston is experiencing the effects of a brief period of accelerated natural fault movement. Available data from monitored faults are insufficient to weigh the relative importance of natural vs. induced fault movements.

Optimization of Deep Drilling Performance--Development and Benchmark Testing of Advanced Diamond Product Drill Bits & HP/HT Fluids to Significantly Improve Rates of Penetration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alan Black; Arnis Judzis

2003-10-01

This document details the progress to date on the OPTIMIZATION OF DEEP DRILLING PERFORMANCE--DEVELOPMENT AND BENCHMARK TESTING OF ADVANCED DIAMOND PRODUCT DRILL BITS AND HP/HT FLUIDS TO SIGNIFICANTLY IMPROVE RATES OF PENETRATION contract for the year starting October 2002 through September 2002. The industry cost shared program aims to benchmark drilling rates of penetration in selected simulated deep formations and to significantly improve ROP through a team development of aggressive diamond product drill bit--fluid system technologies. Overall the objectives are as follows: Phase 1--Benchmark ''best in class'' diamond and other product drilling bits and fluids and develop concepts for amore » next level of deep drilling performance; Phase 2--Develop advanced smart bit--fluid prototypes and test at large scale; and Phase 3--Field trial smart bit--fluid concepts, modify as necessary and commercialize products. Accomplishments to date include the following: 4Q 2002--Project started; Industry Team was assembled; Kick-off meeting was held at DOE Morgantown; 1Q 2003--Engineering meeting was held at Hughes Christensen, The Woodlands Texas to prepare preliminary plans for development and testing and review equipment needs; Operators started sending information regarding their needs for deep drilling challenges and priorities for large-scale testing experimental matrix; Aramco joined the Industry Team as DEA 148 objectives paralleled the DOE project; 2Q 2003--Engineering and planning for high pressure drilling at TerraTek commenced; 3Q 2003--Continuation of engineering and design work for high pressure drilling at TerraTek; Baker Hughes INTEQ drilling Fluids and Hughes Christensen commence planning for Phase 1 testing--recommendations for bits and fluids.« less

Geologic, geophysical, and in situ stress investigations in the vicinity of the Dining Car Chimney, Dining Car/Hybla gold tunnels, Nevada Test Site, with sections on geologica investigations, geophysical investigations, and in situ stress investigations

USGS Publications Warehouse

Townsend, D.R.; Baldwin, M.J.; Carroll, R.D.; Ellis, W.L.; Magner, J.E.

1982-01-01

The Hybla Gold experiment was conducted in the U12e.20 drifts of the E-tunnel complex beneath the surface of Rainier Mesa at the Nevada Test Site. Though the proximity of the Hybla Gold working point to the chimney of the Dining Car event was important to the experiment, the observable geologic effects from Dining Car on the Hybla Gold site were minor. Overburden above the working point is approximately 385 m (1,263 ft). The pre-Tertiary surface, probably quartzite, lies approximately 254 m (833 ft) below the working point. The drifts are mined in zeolitized ash-fall tuffs of tunnel bed 4, subunits K and J, all of Miocene age. The working point is in subunit 4J. Geologic structure in the region around the working point is not complex. The U12e.20 main drift follows the axis of a shallow depositional syncline. A northeast-dipping fault with displacement of approximately 3 m (10 ft) passes within 15.2 m (50 ft) of the Hybla Gold working point. Three faults of smaller displacement pass within 183-290 m (600-950 ft) of the working point, and are antithetic to the 3-m (10-ft) fault. Three exploratory holes were drilled to investigate the chimney of the nearby Dining Car event. Four horizontal holes were drilled during the construction of the U12e.20 drifts to investigate the geology of the Hybla Gold working point.

Scientific drilling into the San Andreas Fault Zone

USGS Publications Warehouse

Zoback, Mark; Hickman, Stephen; Ellsworth, William

2010-01-01

This year, the world has faced energetic and destructive earthquakes almost every month. In January, an M = 7.0 event rocked Haiti, killing an estimated 230,000 people. In February, an M = 8.8 earthquake and tsunami claimed over 500 lives and caused billions of dollars of damage in Chile. Fatal earthquakes also occurred in Turkey in March and in China and Mexico in April.

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

NASA Astrophysics Data System (ADS)

Baker, P. A.; Fritz, S. C.; Silva, C. G.; Rigsby, C. A.; Absy, M. L.; Almeida, R. P.; Caputo, M.; Chiessi, C. M.; Cruz, F. W.; Dick, C. W.; Feakins, S. J.; Figueiredo, J.; Freeman, K. H.; Hoorn, C.; Jaramillo, C.; Kern, A. K.; Latrubesse, E. M.; Ledru, M. P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W. E.; Ramos, M. I. F.; Ribas, C. C.; Trnadade, R.; West, A. J.; Wahnfried, I.; Willard, D. A.

2015-12-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Trans-Amazon Drilling Project (TADP): origins and evolution of the forests, climate, and hydrology of the South American tropics

USGS Publications Warehouse

Baker, P.A.; Fritz, S.C.; Silva, C.G.; Rigsby, C.A.; Absy, M.L.; Almeida, R.P.; Caputo, Maria C.; Chiessi, C.M.; Cruz, F.W.; Dick, C.W.; Feakins, S.J.; Figueiredo, J.; Freeman, K.H.; Hoorn, C.; Jaramillo, C.A.; Kern, A.; Latrubesse, E.M.; Ledru, M.P.; Marzoli, A.; Myrbo, A.; Noren, A.; Piller, W.E.; Ramos, M.I.F.; Ribas, C.C.; Trinadade, R.; West, A.J.; Wahnfried, I.; Willard, Debra A.

2015-01-01

This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to the Atlantic Ocean. The goals of this project are to document the evolution of plant biodiversity in the Amazon forests and to relate biotic diversification to changes in the physical environment, including climate, tectonism, and the surface landscape. These goals require long sedimentary records from each of the major sedimentary basins across the heart of the Brazilian Amazon, which can only be obtained by drilling because of the scarcity of Cenozoic outcrops. The proposed drilling will provide the first long, nearly continuous regional records of the Cenozoic history of the forests, their plant diversity, and the associated changes in climate and environment. It also will address fundamental questions about landscape evolution, including the history of Andean uplift and erosion as recorded in Andean foreland basins and the development of west-to-east hydrologic continuity between the Andes, the Amazon lowlands, and the equatorial Atlantic. Because many modern rivers of the Amazon basin flow along the major axes of the old sedimentary basins, we plan to locate drill sites on the margin of large rivers and to access the targeted drill sites by navigation along these rivers.

Magnetic behaviors of cataclasites within Wenchuan earthquake fault zone in heating experiments

NASA Astrophysics Data System (ADS)

Zhang, L.; Li, H.; Sun, Z.; Chou, Y. M.; Cao, Y., Jr.; Huan, W.; Ye, X.; He, X.

2017-12-01

Previous rock magnetism of fault rocks were used to trace the frictional heating temperature, however, few studies are focus on different temperatures effect of rock magnetic properties. To investigate rock magnetic response to different temperature, we conducted heating experiments on cataclasites from the Wenchuan earthquake Fault Scientific Drilling borehole 2 (WFSD-2) cores. Samples of cataclasites were obtained using an electric drill with a 1 cm-diameter drill pipe from 580.65 m-depth. Experiments were performed by a Thermal-optical measurement system under argon atmosphere and elevated temperatures. Both microstructural observations and powder X-ray diffraction analyses show that feldspar and quartz start to melt at 1100 ° and 1300 ° respectively. Magnetic susceptibility values of samples after heating are higher than that before heating. Samples after heating at 700 and 1750 ° have the highest values of magnetic susceptibility. Rock magnetic measurements show that the main ferromagnetic minerals within samples heated below 1100 ° (400, 700, 900 and 1100 °) are magnetite, which is new-formed by transformation of paramagnetic minerals. The χferri results show that the quantity of magnetite is bigger at sample heated by 700° experiment than by 400, 900 and 1100° experiments. Based on the FORC diagrams, we consider that magnetite grains are getting finer from 400 to 900°, and growing coarser when heated from 900 to 1100 °. SEM-EDX results indicate that the pure iron are formed in higher temperature (1300, 1500 and 1750 °), which present as framboids with size <10 μm. Rock magnetic measurements imply pure iron is the main ferromagnetic materials in these heated samples. The amount and size of iron framboids increase with increasing temperature. Therefore, we conclude that the paramagnetic minerals are decomposed into fine magnetite, then to coarse-grained magnetite, finally to pure iron at super high temperature. New-formed magnetite contributes to the higher magnetic susceptibility values of samples when heated at 400, 700, 900 and 1100°, while the neoformed pure iron is responsible to the higher magnetic susceptibility values of samples when heated at 1300, 1500 and 1750°.

Cooling rates and the depth of detachment faulting at oceanic core complexes: Evidence from zircon Pb/U and (U-Th)/He ages

USGS Publications Warehouse

Grimes, Craig B.; Cheadle, Michael J.; John, Barbara E.; Reiners, P.W.; Wooden, J.L.

2011-01-01

Oceanic detachment faulting represents a distinct mode of seafloor spreading at slow spreading mid-ocean ridges, but many questions persist about the thermal evolution and depth of faulting. We present new Pb/U and (U-Th)/He zircon ages and combine them with magnetic anomaly ages to define the cooling histories of gabbroic crust exposed by oceanic detachment faults at three sites along the Mid-Atlantic Ridge (Ocean Drilling Program (ODP) holes 1270D and 1275D near the 15??20???N Transform, and Atlantis Massif at 30??N). Closure temperatures for the Pb/U (???800??C-850??C) and (U-Th)/He (???210??C) isotopic systems in zircon bracket acquisition of magnetic remanence, collectively providing a temperature-time history during faulting. Results indicate cooling to ???200??C in 0.3-0.5 Myr after zircon crystallization, recording time-averaged cooling rates of ???1000??C- 2000??C/Myr. Assuming the footwalls were denuded along single continuous faults, differences in Pb/U and (U-Th)/He zircon ages together with independently determined slip rates allow the distance between the ???850??C and ???200??C isotherms along the fault plane to be estimated. Calculated distances are 8.4 ?? 4.2 km and 5.0 2.1 km from holes 1275D and 1270D and 8.4 ?? 1.4 km at Atlantis Massif. Estimating an initial subsurface fault dip of 50 and a depth of 1.5 km to the 200??C isotherm leads to the prediction that the ???850??C isotherm lies ???5-7 km below seafloor at the time of faulting. These depth estimates for active fault systems are consistent with depths of microseismicity observed beneath the hypothesized detachment fault at the TAG hydrothermal field and high-temperature fault rocks recovered from many oceanic detachment faults. Copyright 2011 by the American Geophysical Union.

Final Technical Report: PV Fault Detection Tool.

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, Bruce Hardison; Jones, Christian Birk

The PV Fault Detection Tool project plans to demonstrate that the FDT can (a) detect catastrophic and degradation faults and (b) identify the type of fault. This will be accomplished by collecting fault signatures using different instruments and integrating this information to establish a logical controller for detecting, diagnosing and classifying each fault.

Seismic reflection evidence for a northeast-dipping Hayward fault near Fremont, California: Implications for seismic hazard

USGS Publications Warehouse

Williams, R.A.; Simpson, R.W.; Jachens, R.C.; Stephenson, W.J.; Odum, J.K.; Ponce, D.A.

2005-01-01

A 1.6-km-long seismic reflection profile across the creeping trace of the southern Hayward fault near Fremont, California, images the fault to a depth of 650 m. Reflector truncations define a fault dip of about 70 degrees east in the 100 to 650 m depth range that projects upward to the creeping surface trace, and is inconsistent with a nearly vertical fault in this vicinity as previously believed. This fault projects to the Mission seismicity trend located at 4-10 km depth about 2 km east of the surface trace and suggests that the southern end of the fault is as seismically active as the part north of San Leandro. The seismic hazard implication is that the Hayward fault may have a more direct connection at depth with the Calaveras fault, affecting estimates of potential event magnitudes that could occur on the combined fault surfaces, thus affecting hazard assessments for the south San Francisco Bay region.

Italian river crossing; Horizontal drilling meets pipeline project criteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1988-06-01

The River Piave flows out of the Italian Alps, crossing the Veneto farmlands on its way to the Adriatic Sea. It is an important commerce-carrying waterway. SNAM, the Italian state gas pipeline company, wanted to install a 22-in. pipeline across the Piave just north of Venice. The method chosen for crossing the river had to meet several important criteria. InArc had used its river crossing method on seven previous SNAM projects and recommended the Piave crossing should be drilled. This paper describes the use of this horizontal drilling method for this application.

Coccolith and silicoflagellate stratigraphy, northern mid-Atlantic Ridge and Reykjanes Ridge, Deep Sea Drilling Project Leg 49

USGS Publications Warehouse

Bukry, David

1979-01-01

Leg 49 of the Deep Sea Drilling Project recovered 192 cores at eight drilling sites, 407 through 414 (Figure 1). Light-microscope techniques were used to study the cocoliths, silicoflagellates, and sponge spicules of 120 samples from these cores. The cocolith zonation of the samples follows Bukry (1975a), and is summarized in Figure 2. Silicoflagellate zonation, summarized in Figure 3, is explained in the text. Siliceous sponge spicules are common in many samples and are briefly discussed and illustrated. One new silicoflagellate, Distephanus sulcatus, from the Plicene of Site 407, is described.

Seismic Velocity and Elastic Properties of Plate Boundary Faults

NASA Astrophysics Data System (ADS)

Jeppson, Tamara N.

The elastic properties of fault zone rock at depth play a key role in rupture nucleation, propagation, and the magnitude of fault slip. Materials that lie within major plate boundary fault zones often have very different material properties than standard crustal rock values. In order to understand the mechanics of faulting at plate boundaries, we need to both measure these properties and understand how they govern the behavior of different types of faults. Mature fault zones tend to be identified in large-scale geophysical field studies as zones with low seismic velocity and/or electrical resistivity. These anomalous properties are related to two important mechanisms: (1) mechanical or diagenetic alteration of the rock materials and/or (2) pore fluid pressure and stress effects. However, in remotely-sensed and large-length-scale data it is difficult to determine which of these mechanisms are affecting the measured properties. The objective of this dissertation research is to characterize the seismic velocity and elastic properties of fault zone rocks at a range of scales, with a focus on understanding why the fault zone properties are different from those of the surrounding rock and the potential effects on earthquake rupture and fault slip. To do this I performed ultrasonic velocity experiments under elevated pressure conditions on drill core and outcrops samples from three plate boundary fault zones: the San Andreas Fault, California, USA; the Alpine Fault, South Island, New Zealand; and the Japan Trench megathrust, Japan. Additionally, I compared laboratory measurements to sonic log and large-scale seismic data to examine the scale-dependence of the measured properties. The results of this study provide the most comprehensive characterization of the seismic velocities and elastic properties of fault zone rocks currently available. My work shows that fault zone rocks at mature plate boundary faults tend to be significantly more compliant than surrounding crustal rocks and quantifies that relationship. The results of this study are particularly relevant to the interpretation of field-scale seismic datasets at major fault zones. Additionally, the results of this study provide constraints on elastic properties used in dynamic rupture models.

Experimental study of the effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid

NASA Astrophysics Data System (ADS)

yang, P.

2013-12-01

Experimental study of the effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid Ping Yang 1,2, Min-hui Wu2, Xue-wen Zhu2, Tao Deng2, Xue-qing Sun2 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092,China 2. Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China Abstract The process of filtrate loss of low-solids drilling fluid was tested by changing the polyanionic cellulose content in low-solids drilling fluid. The effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid was analyzed. The test results showed that when time of filtration is same, the volume of filtrate loss decreases linearly with increasing polyanionic cellulose content. When polyanionic cellulose content is same, the rate of filtrate loss decreases nonlinearly with increasing time and the rate of filtrate loss will reach a stable value.The volume of filtrate loss in 7 to 8 minutes can reaches half of the total volume of filtrate loss. At the same time, the rate of filtrate loss of drilling fluid decreases nonlinearly with increasing viscosity.When the apparent viscosity is between 3.5~4.15 MPa.s, decrease speed of rate of filtrate loss of drilling fluid is quick. The results are helpful for characteristics evaluation of filtrate loss of drilling fluid and control of filtrate loss. Keyword Polyanionic Cellulose,Drilling Fluid,Process of Filtrate Loss Acknowledgments This investigation was supported by the National Natural Science Foundation of China (projects No. 41002093 and 41072205); the Fundamental Research Funds for the Central Universities; the Shanghai Leading Academic Discipline Project (project No. B308), Tongji University; and the Program for Young Excellent Talents, Tongji University. The authors are extremely grateful for the financial support from these five organizations.

OM300 Direction Drilling Module

DOE Data Explorer

MacGugan, Doug

2013-08-22

OM300 – Geothermal Direction Drilling Navigation Tool: Design and produce a prototype directional drilling navigation tool capable of high temperature operation in geothermal drilling Accuracies of 0.1° Inclination and Tool Face, 0.5° Azimuth Environmental Ruggedness typical of existing oil/gas drilling Multiple Selectable Sensor Ranges High accuracy for navigation, low bandwidth High G-range & bandwidth for Stick-Slip and Chirp detection Selectable serial data communications Reduce cost of drilling in high temperature Geothermal reservoirs Innovative aspects of project Honeywell MEMS* Vibrating Beam Accelerometers (VBA) APS Flux-gate Magnetometers Honeywell Silicon-On-Insulator (SOI) High-temperature electronics Rugged High-temperature capable package and assembly process

Oceanic Basement Probed

ERIC Educational Resources Information Center

Cann, J. R.; Moore, David G.

1978-01-01

Summarizes findings of the deep sea drilling project at Scripps Institute of Oceanology. Results of Atlantic and Pacific Ocean drillings in terms of the composition and properties of the sea floor are discussed. (CP)

The Chaîne des Puys and Limagne Fault World Heritage project: a view from a scientist

NASA Astrophysics Data System (ADS)

van Wyk de Vries, B.

2013-12-01

The development of the Chaîne des Puys and Limagne Fault World Heritage UNESCO project has taken about five years, since the Laboratoire Magmas et Volcans was approached by the local Auvergne government. Before this we had been working locally with organisations such as the Lemptégy volcano and Vulcania to help disseminate geoscience ideas to the general public, however the UNESCO project has lead us to do much more outreach. It has also stimulated our research and has taught us to better explain this to the lay person. In visiting other heritage projects, where we have exchanged ideas and best practice, we have been able to help other sites and improve what we do. These links are particularly important, as they can be used to help broaden the outlook of the general public and local actors, and increase further earth science literacy. I have noticed a strong increase in the awareness of the volcanoes, and volcanism as a result of the Chaîne des Puys and Limagne Fault project. I think that, before, many locals considered the volcanoes only as their special back garden, for easy walks and views and leisure, or for that matter farming, mining and hunting. However, now, there is a greater sense of pride rooted in the increased awareness of their geological significance in a historical and global context. While this effect is clear for the volcanoes, it is not yet apparent for the fault. The lay person has no clear concept of a rift and a fault. Thus, one of our major present challenges is to open the public's eyes to the fault. This is vital for the UNESCO project not only for educational reasons, but also because the fault scarp is a natural barrier that protects the rest of the property from urban development. Only if there is awareness of its nature and significance will it be an effective defence. To arrive at this goal, there is now a local government sponsored project to create and disseminate fault walks, fault viewpoints and fault information points. This is made easier, as local attractions, such as Volvic water, Lémptégy and Vulcania already all have a tectonic angle to their presentations. The difference from previous outreach efforts is that this project is focussed directly on raising understanding about a tectonic feature for very clear strategic goals. This uses the realisation that increased public understanding can be used as a powerful force to help protect sites.

Faulting and groundwater in a desert environment: constraining hydrogeology using time-domain electromagnetic data

USGS Publications Warehouse

Bedrosian, Paul A.; Burgess, Matthew K.; Nishikawa, Tracy

2013-01-01

Within the south-western Mojave Desert, the Joshua Basin Water District is considering applying imported water into infiltration ponds in the Joshua Tree groundwater sub-basin in an attempt to artificially recharge the underlying aquifer. Scarce subsurface hydrogeological data are available near the proposed recharge site; therefore, time-domain electromagnetic (TDEM) data were collected and analysed to characterize the subsurface. TDEM soundings were acquired to estimate the depth to water on either side of the Pinto Mountain Fault, a major east-west trending strike-slip fault that transects the proposed recharge site. While TDEM is a standard technique for groundwater investigations, special care must be taken when acquiring and interpreting TDEM data in a twodimensional (2D) faulted environment. A subset of the TDEM data consistent with a layered-earth interpretation was identified through a combination of three-dimensional (3D) forward modelling and diffusion time-distance estimates. Inverse modelling indicates an offset in water table elevation of nearly 40 m across the fault. These findings imply that the fault acts as a low-permeability barrier to groundwater flow in the vicinity of the proposed recharge site. Existing production wells on the south side of the fault, together with a thick unsaturated zone and permeable near-surface deposits, suggest the southern half of the study area is suitable for artificial recharge. These results illustrate the effectiveness of targeted TDEM in support of hydrological studies in a heavily faulted desert environment where data are scarce and the cost of obtaining these data by conventional drilling techniques is prohibitive.

Low resistivity and permeability in actively deforming shear zones on the San Andreas Fault at SAFOD

USGS Publications Warehouse

Morrow, Carolyn A.; Lockner, David A.; Hickman, Stephen H.

2015-01-01

The San Andreas Fault Observatory at Depth (SAFOD) scientific drillhole near Parkfield, California crosses the San Andreas Fault at a depth of 2.7 km. Downhole measurements and analysis of core retrieved from Phase 3 drilling reveal two narrow, actively deforming zones of smectite-clay gouge within a roughly 200 m-wide fault damage zone of sandstones, siltstones and mudstones. Here we report electrical resistivity and permeability measurements on core samples from all of these structural units at effective confining pressures up to 120 MPa. Electrical resistivity (~10 ohm-m) and permeability (10-21 to 10-22 m2) in the actively deforming zones were one to two orders of magnitude lower than the surrounding damage zone material, consistent with broader-scale observations from the downhole resistivity and seismic velocity logs. The higher porosity of the clay gouge, 2 to 8 times greater than that in the damage zone rocks, along with surface conduction were the principal factors contributing to the observed low resistivities. The high percentage of fine-grained clay in the deforming zones also greatly reduced permeability to values low enough to create a barrier to fluid flow across the fault. Together, resistivity and permeability data can be used to assess the hydrogeologic characteristics of the fault, key to understanding fault structure and strength. The low resistivities and strength measurements of the SAFOD core are consistent with observations of low resistivity clays that are often found in the principal slip zones of other active faults making resistivity logs a valuable tool for identifying these zones.

Core-log integration for rock mechanics using borehole breakouts and rock strength experiments: Recent results from plate subduction margins

NASA Astrophysics Data System (ADS)

Saito, S.; Lin, W.

2014-12-01

Core-log integration has been applied for rock mechanics studies in scientific ocean drilling since 2007 in plate subduction margins such as Nankai Trough, Costa Rica margin, and Japan Trench. State of stress in subduction wedge is essential for controlling dynamics of plate boundary fault. One of the common methods to estimate stress state is analysis of borehole breakouts (drilling induced borehole wall compressive failures) recorded in borehole image logs to determine the maximum horizontal principal stress orientation. Borehole breakouts can also yield possible range of stress magnitude based on a rock compressive strength criterion. In this study, we constrained the stress magnitudes based on two different rock failure criteria, the Mohr-Coulomb (MC) criteria and the modified Wiebols-Cook (mWC) criteria. As the MC criterion is the same as that under unconfined compression state, only one rock parameter, unconfined compressive strength (UCS) is needed to constrain stress magnitudes. The mWC criterion needs the UCS, Poisson's ratio and internal frictional coefficient determined by triaxial compression experiments to take the intermediate principal stress effects on rock strength into consideration. We conducted various strength experiments on samples taken during IODP Expeditions 334/344 (Costa Rica Seismogenesis Project) to evaluate reliable method to estimate stress magnitudes. Our results show that the effects of the intermediate principal stress on the rock compressive failure occurred on a borehole wall is not negligible.

Ocean Drilling Program: Drilling Services

Science.gov Websites

Drilling operations team Material services team Development engineering team ODP/TAMU Science Operator Home Services department consists of three team-oriented project groups, which also work to improve the existing team. A member of this team sails with each cruise to provide expertise for the shipboard scientific

Characterizing the Potential for Injection-Induced Fault Reactivation Through Subsurface Structural Mapping and Stress Field Analysis, Wellington Field, Sumner County, Kansas

NASA Astrophysics Data System (ADS)

Schwab, Drew R.; Bidgoli, Tandis S.; Taylor, Michael H.

2017-12-01

Kansas, like other parts of the central U.S., has experienced a recent increase in seismicity. Correlation of these events with brine disposal operations suggests pore fluid pressure increases are reactivating preexisting faults, but rigorous evaluation at injection sites is lacking. Here we determine the suitability of CO2 injection into the Cambrian-Ordovician Arbuckle Group for long-term storage and into a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. To determine the potential for injection-induced earthquakes, we map subsurface faults and estimate in situ stresses, perform slip and dilation tendency analyses to identify well-oriented faults relative to the estimated stress field, and determine the pressure changes required to induce slip at reservoir and basement depths. Three-dimensional seismic reflection data reveal 12 near-vertical faults, mostly striking NNE, consistent with nodal planes from moment tensor solutions from recent earthquakes in the region. Most of the faults cut both reservoirs and several clearly penetrate the Precambrian basement. Drilling-induced fractures (N = 40) identified from image logs and inversion of earthquake moment tensor solutions (N = 65) indicate that the maximum horizontal stress is approximately EW. Slip tendency analysis indicates that faults striking <020° are stable under current reservoir conditions, whereas faults striking 020°-049° may be prone to reactivation with increasing pore fluid pressure. Although the proposed injection volume (40,000 t) is unlikely to reactive faults at reservoir depths, high-rate injection operations could reach pressures beyond the critical threshold for slip within the basement, as demonstrated by the large number of injection-induced earthquakes west of the study area.

Structural style and hydrocarbon trap of Karbasi anticline, in the Interior Fars region, Zagros, Iran

NASA Astrophysics Data System (ADS)

Maleki, Z.; Arian, M.; Solgi, A.

2014-07-01

Karbasi anticline between west-northwest parts of Jahrom town is located in northwest 40 km distance of Aghar gas anticline in interior Fars region. This anticline has asymmetric structure and some faults with large strike separation observed in its structure. The operation of Nezamabad sinistral strike slip fault in west part of this anticline caused fault plunge change in this region. Because of complication increasing of structures geometry in Fars region and necessity to exploration activities for deeper horizons especially the Paleozoic ones, the analysis of fold style elements, which is known as one of the main parts in structural studies seems necessary. In this paper because of some reasons such as Karbasi anticline structural complication, importance of drilling and hydrocarbon explorations in Fars region, it is proceed to analysis and evaluation of fold style elements and geometry with emphasis on Nezamabad fault operation in Interior Fars region. According to fold style elements analysis results, it became clear that in east part of anticline the type of fold horizontal moderately inclined and in west part it is upright moderately plunging, so west evaluation of anticline is affected by more deformation. In this research the relationship present faults especially the Nezamabad sinistral strike slip one with folding and its affection on Dehram horizon and Bangestan group were modeled. Based on received results may be the Nezamabad fault is located between G-G' and E-E' structural sections and this fault in this area operated same as fault zone. In different parts of Karbasi anticline, Dashtak formation as a middle detachment unit plays an important role in connection to folding geometry, may be which is affected by Nezamabad main fault.

Extreme hydrothermal conditions at an active plate-bounding fault.

PubMed

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G R; Janku-Capova, Lucie; Carpenter, Brett M; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Extreme hydrothermal conditions at an active plate-bounding fault

NASA Astrophysics Data System (ADS)

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G. R.; Janku-Capova, Lucie; Carpenter, Brett M.; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R.; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Marcellus Shale Drilling's Impact on the Dairy Industry in Pennsylvania: A Descriptive Report.

PubMed

Finkel, Madelon L; Selegean, Jane; Hays, Jake; Kondamudi, Nitin

2013-01-01

Unconventional natural gas drilling in Pennsylvania has accelerated over the past five years, and is unlikely to abate soon. Dairy farming is a large component of Pennsylvania's agricultural economy. This study compares milk production, number of cows, and production per cow in counties with significant unconventional drilling activity to that in neighboring counties with less unconventional drilling activity, from 1996 through 2011. Milk production and milk cows decreased in most counties since 1996, with larger decreases occurring from 2007 through 2011 (when unconventional drilling increased substantially) in five counties with the most wells drilled compared to six adjacent counties with fewer than 100 wells drilled. While this descriptive study cannot draw a causal association between well drilling and decline in cows or milk production, given the importance of Pennsylvania's dairy industry and the projected increase in unconventional natural gas drilling, further research to prevent unintended economic and public health consequences is imperative.

An integrated geophysical study on the Mesozoic strata distribution and hydrocarbon potential in the South China Sea

NASA Astrophysics Data System (ADS)

Hu, Weijian; Hao, Tianyao; Jiang, Weiwei; Xu, Ya; Zhao, Baimin; Jiang, Didi

2015-11-01

A series of drilling, dredge, and seismic investigations indicate that Mesozoic sediments exist in the South China Sea (SCS) which shows a bright prospect for oil and gas exploration. In order to study the distribution of Mesozoic strata and their residual thicknesses in the SCS, we carried out an integrated geophysical study based mainly on gravity data, gravity basement depth and distribution of residual Mesozoic thickness in the SCS were obtained using gravity inversion constrained with high-precision drilling and seismic data. In addition, the fine deep crustal structures and distribution characteristics of Mesozoic thicknesses of three typical profiles were obtained by gravity fitting inversion. Mesozoic strata in the SCS are mainly distributed in the south and north continental margins, and have been reformed by the later tectonic activities. They extend in NE-trending stripes are macro-controlled by the deep and large NE-trending faults, and cut by the NW-trending faults which were active in later times. The offset in NW direction of Mesozoic strata in Nansha area of the southern margin are more obvious as compared to the north margin. In the Pearl River Mouth Basin and Southwest Taiwan Basin of the north continental margin the Mesozoic sediments are continuously distributed with a relatively large thickness. In the Nansha area of the south margin the Mesozoic strata are discontinuous and their thicknesses vary considerably. According to the characteristics of Mesozoic thickness distribution and hydrocarbon potential analyses from drilling and other data, Dongsha Uplift-Chaoshan Depression, Southwest Taiwan Basin-Peikang Uplift and Liyue Bank have large thickness of the Mesozoic residual strata, have good hydrocarbon genesis capability and complete source-reservoir-cap combinations, show a bright prospect of Mesozoic oil/gas resources.

Reporting from the Iceland Deep Drilling Project

NASA Astrophysics Data System (ADS)

Urban, Karl

2017-04-01

Geoscience-related topics are in many cases difficult to communicate to the public: Often they include dead soil which not easily tells lively stories. And it is hard to sell those topics to editors of public media. In addition the topics might also be politically supercharged if they are resource-related with a visible environmental impact. Therefore any researcher involved might be overcautious while talking to journalists. With a grant from the EGU Science Journalist Fellowship I travelled to Iceland in autumn 2016 to report about the Iceland Deep Drilling Project (IDDP). The project which started just weeks prior to my arrival aimed to drill the deepest borehole in a volcanically active region. During earlier trials the borehole collapsed or the drill string unintentionally hit magma. If successful the IDDP promises a much higher level of geothermal energy harvested. The IDDP was therefore ideally suited to be sold to public media outlets since Iceland's volcanic legacy easily tells a lively story. But the drilling's potential environmental impact makes it a political topic in Iceland - even though geothermal energy has a positive public perception. Therefore the IDDP included some pitfalls I observed several times before while reporting about geoscience research. Those could be circumvented if researchers and journalists knew better about their expectations before any interview takes place.

Multi-Fault Diagnosis of Rolling Bearings via Adaptive Projection Intrinsically Transformed Multivariate Empirical Mode Decomposition and High Order Singular Value Decomposition

PubMed Central

Lv, Yong; Song, Gangbing

2018-01-01

Rolling bearings are important components in rotary machinery systems. In the field of multi-fault diagnosis of rolling bearings, the vibration signal collected from single channels tends to miss some fault characteristic information. Using multiple sensors to collect signals at different locations on the machine to obtain multivariate signal can remedy this problem. The adverse effect of a power imbalance between the various channels is inevitable, and unfavorable for multivariate signal processing. As a useful, multivariate signal processing method, Adaptive-projection has intrinsically transformed multivariate empirical mode decomposition (APIT-MEMD), and exhibits better performance than MEMD by adopting adaptive projection strategy in order to alleviate power imbalances. The filter bank properties of APIT-MEMD are also adopted to enable more accurate and stable intrinsic mode functions (IMFs), and to ease mode mixing problems in multi-fault frequency extractions. By aligning IMF sets into a third order tensor, high order singular value decomposition (HOSVD) can be employed to estimate the fault number. The fault correlation factor (FCF) analysis is used to conduct correlation analysis, in order to determine effective IMFs; the characteristic frequencies of multi-faults can then be extracted. Numerical simulations and the application of multi-fault situation can demonstrate that the proposed method is promising in multi-fault diagnoses of multivariate rolling bearing signal. PMID:29659510

Multi-Fault Diagnosis of Rolling Bearings via Adaptive Projection Intrinsically Transformed Multivariate Empirical Mode Decomposition and High Order Singular Value Decomposition.

PubMed

Yuan, Rui; Lv, Yong; Song, Gangbing

2018-04-16

Rolling bearings are important components in rotary machinery systems. In the field of multi-fault diagnosis of rolling bearings, the vibration signal collected from single channels tends to miss some fault characteristic information. Using multiple sensors to collect signals at different locations on the machine to obtain multivariate signal can remedy this problem. The adverse effect of a power imbalance between the various channels is inevitable, and unfavorable for multivariate signal processing. As a useful, multivariate signal processing method, Adaptive-projection has intrinsically transformed multivariate empirical mode decomposition (APIT-MEMD), and exhibits better performance than MEMD by adopting adaptive projection strategy in order to alleviate power imbalances. The filter bank properties of APIT-MEMD are also adopted to enable more accurate and stable intrinsic mode functions (IMFs), and to ease mode mixing problems in multi-fault frequency extractions. By aligning IMF sets into a third order tensor, high order singular value decomposition (HOSVD) can be employed to estimate the fault number. The fault correlation factor (FCF) analysis is used to conduct correlation analysis, in order to determine effective IMFs; the characteristic frequencies of multi-faults can then be extracted. Numerical simulations and the application of multi-fault situation can demonstrate that the proposed method is promising in multi-fault diagnoses of multivariate rolling bearing signal.

ADVANCED CUTTINGS TRANSPORT STUDY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stefan Miska; Troy Reed; Ergun Kuru

2004-09-30

The Advanced Cuttings Transport Study (ACTS) was a 5-year JIP project undertaken at the University of Tulsa (TU). The project was sponsored by the U.S. Department of Energy (DOE) and JIP member companies. The objectives of the project were: (1) to develop and construct a new research facility that would allow three-phase (gas, liquid and cuttings) flow experiments under ambient and EPET (elevated pressure and temperature) conditions, and at different angle of inclinations and drill pipe rotation speeds; (2) to conduct experiments and develop a data base for the industry and academia; and (3) to develop mechanistic models for optimizationmore » of drilling hydraulics and cuttings transport. This project consisted of research studies, flow loop construction and instrumentation development. Following a one-year period for basic flow loop construction, a proposal was submitted by TU to the DOE for a five-year project that was organized in such a manner as to provide a logical progression of research experiments as well as additions to the basic flow loop. The flow loop additions and improvements included: (1) elevated temperature capability; (2) two-phase (gas and liquid, foam etc.) capability; (3) cuttings injection and removal system; (4) drill pipe rotation system; and (5) drilling section elevation system. In parallel with the flow loop construction, hydraulics and cuttings transport studies were preformed using drilling foams and aerated muds. In addition, hydraulics and rheology of synthetic drilling fluids were investigated. The studies were performed under ambient and EPET conditions. The effects of temperature and pressure on the hydraulics and cuttings transport were investigated. Mechanistic models were developed to predict frictional pressure loss and cuttings transport in horizontal and near-horizontal configurations. Model predictions were compared with the measured data. Predominantly, model predictions show satisfactory agreements with the measured data. As a part of this project, instrumentation was developed to monitor cuttings beds and characterize foams in the flow loop. An ultrasonic-based monitoring system was developed to measure cuttings bed thickness in the flow loop. Data acquisition software controls the system and processes the data. Two foam generating devices were designed and developed to produce foams with specified quality and texture. The devices are equipped with a bubble recognition system and an in-line viscometer to measure bubble size distribution and foam rheology, respectively. The 5-year project is completed. Future research activities will be under the umbrella of Tulsa University Drilling Research Projects. Currently the flow loop is being used for testing cuttings transport capacity of aqueous and polymer-based foams under elevated pressure and temperature conditions. Subsequently, the effect of viscous sweeps on cuttings transport under elevated pressure and temperature conditions will be investigated using the flow loop. Other projects will follow now that the ''steady state'' phase of the project has been achieved.« less

OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE - A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon Tibbitts; Arnis Judzis

2002-04-01

This document details the progress to date on the OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE--A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING contract for the quarter starting January 2002 through March 2002. Accomplishments include the following: In accordance to Task 7.0 (D. No.2 Technical Publications) TerraTek, NETL, and the Industry Contributors successfully presented a paper detailing Phase 1 testing results at the February 2002 IADC/SPE Drilling Conference, a prestigious venue for presenting DOE and private sector drilling technology advances. The full reference is as follows: (1) IADC/SPE 74540 ''World's First Benchmarking of Drilling Mud Hammer Performance atmore » Depth Conditions'' authored by Gordon A. Tibbitts, TerraTek; Roy C. Long, US Department of Energy, Brian E. Miller, BP America, Inc.; Arnis Judzis, TerraTek; and Alan D. Black, TerraTek. Gordon Tibbitts, TerraTek, will presented the well-attended paper in February of 2002. The full text of the Mud Hammer paper was included in the last quarterly report. (2) The Phase 2 project planning meeting (Task 6) was held at ExxonMobil's Houston Greenspoint offices on February 22, 2002. In attendance were representatives from TerraTek, DOE, BP, ExxonMobil, PDVSA, Novatek, and SDS Digger Tools. (3) PDVSA has joined the advisory board to this DOE mud hammer project. PDVSA's commitment of cash and in-kind contributions were reported during the last quarter. (4) Strong Industry support remains for the DOE project. Both Andergauge and Smith Tools have expressed an interest in participating in the ''optimization'' phase of the program. The potential for increased testing with additional Industry cash support was discussed at the planning meeting in February 2002.« less

A Green's function approach for assessing the thermal disturbance caused by drilling deep boreholes in rock or ice

USGS Publications Warehouse

Clow, Gary D.

2015-01-01

A knowledge of subsurface temperatures in sedimentary basins, fault zones, volcanic environments and polar ice sheets is of interest for a wide variety of geophysical applications. However, the process of drilling deep boreholes in these environments to provide access for temperature and other measurements invariably disturbs the temperature field around a newly created borehole. Although this disturbance dissipates over time, most temperature measurements are made while the temperature field is still disturbed. Thus, the measurements must be ‘corrected’ for the drilling-disturbance effect if the undisturbed temperature field is to be determined. This paper provides compact analytical solutions for the thermal drilling disturbance based on 1-D (radial) and 2-D (radial and depth) Green's functions (GFs) in cylindrical coordinates. Solutions are developed for three types of boundary conditions (BCs) at the borehole wall: (1) prescribed temperature, (2) prescribed heat flux and (3) a prescribed convective condition. The BC at the borehole wall is allowed to vary both with depth and time. Inclusion of the depth dimension in the 2-D solution allows vertical heat-transfer effects to be quantified in situations where they are potentially important, that is, near the earth's surface, at the bottom of a well and when considering finite-drilling rates. The 2-D solution also includes a radial- and time-dependent BC at the earth's surface to assess the impact of drilling-related infrastructure (drilling pads, mud pits, permanent shelters) on the subsurface temperature field. Latent-heat effects due to the melting and subsequent refreezing of interstitial ice while drilling a borehole through ice-rich permafrost can be included in the GF solution as a moving-plane heat source (or sink) located at the solid–liquid interface. Synthetic examples are provided illustrating the 1-D and 2-D GF solutions. The flexibility of the approach allows the investigation of thermal drilling effects in rock or ice for a wide variety of drilling technologies. Numerical values for the required radial GFs GR are available through the Advanced Cooperative Arctic Data and Information Service at doi:10.5065/D64F1NS6.

Frictional and hydraulic behaviour of carbonate fault gouge during fault reactivation - An experimental study

NASA Astrophysics Data System (ADS)

Delle Piane, Claudio; Giwelli, Ausama; Clennell, M. Ben; Esteban, Lionel; Nogueira Kiewiet, Melissa Cristina D.; Kiewiet, Leigh; Kager, Shane; Raimon, John

2016-10-01

We present a novel experimental approach devised to test the hydro-mechanical behaviour of different structural elements of carbonate fault rocks during experimental re-activation. Experimentally faulted core plugs were subject to triaxial tests under water saturated conditions simulating depletion processes in reservoirs. Different fault zone structural elements were created by shearing initially intact travertine blocks (nominal size: 240 × 110 × 150 mm) to a maximum displacement of 20 and 120 mm under different normal stresses. Meso-and microstructural features of these sample and the thickness to displacement ratio characteristics of their deformation zones allowed to classify them as experimentally created damage zones (displacement of 20 mm) and fault cores (displacement of 120 mm). Following direct shear testing, cylindrical plugs with diameter of 38 mm were drilled across the slip surface to be re-activated in a conventional triaxial configuration monitoring the permeability and frictional behaviour of the samples as a function of applied stress. All re-activation experiments on faulted plugs showed consistent frictional response consisting of an initial fast hardening followed by apparent yield up to a friction coefficient of approximately 0.6 attained at around 2 mm of displacement. Permeability in the re-activation experiments shows exponential decay with increasing mean effective stress. The rate of permeability decline with mean effective stress is higher in the fault core plugs than in the simulated damage zone ones. It can be concluded that the presence of gouge in un-cemented carbonate faults results in their sealing character and that leakage cannot be achieved by renewed movement on the fault plane alone, at least not within the range of slip measureable with our apparatus (i.e. approximately 7 mm of cumulative displacement). Additionally, it is shown that under sub seismic slip rates re-activated carbonate faults remain strong and no frictional weakening was observed during re-activation.

Calibrating the Truax Rough Rider seed drill for restoration plantings

Treesearch

Loren St. John; Brent Cornforth; Boyd Simonson; Dan Ogle; Derek Tilley

2008-01-01

The purpose of this technical note is to provide a step-by-step approach to calibrating the Truax Rough Rider range drill, a relatively new, state-of-the-art rangeland drill. To achieve the desired outcome of a seeding project, an important step following proper weed control and seedbed preparation is the calibration of the seeding equipment to ensure the recommended...

Data Modeling, Development, Installation and Operation of the ACEX Offshore Drilling Information System for the Mission Specific Platform Expedition to the Lomonosov Ridge, Arctic Ocean.

NASA Astrophysics Data System (ADS)

Conze, R.; Krysiak, F.; Wallrabe-Adams, H.; Graham, C. C.

2004-12-01

During August/September 2004, the Arctic Coring Expedition (ACEX) was used to trial a new Offshore Drilling Information System (OffshoreDIS). ACEX was the first Mission Specific Platform (MSP) expedition of the Integrated Ocean Drilling Programme (IODP), funded by the European Consortium for Ocean Research Drilling (ECORD). The British Geological Survey in conjunction with the University of Bremen and the European Petrophysics Consortium were the ECORD Science Operator (ESO) for ACEX. IODP MSP expeditions have very similar data management requirements and operate in similar working environments to the lake drilling projects conducted by the International Continental Scientific Drilling Program (ICDP), for example, the GLAD800, which has very restricted space on board and operates in difficult conditions. Both organizations require data capture and management systems that are mobile, flexible and that can be deployed quickly on small- to medium-sized drilling platforms for the initial gathering of data, and that can also be deployed onshore in laboratories where the bulk of the scientific work is conducted. ESO, therefore, decided that an adapted version of the existing Drilling Information System (DIS) used by ICDP projects would satisfy its requirements. Based on the existing DIS, an OffshoreDIS has been developed for MSP expeditions. The underlying data model is compatible with IODP(JANUS), the Bremen Core Repository, WDC-MARE/PANGAEA and the LacCore in Minneapolis. According to the specific expedition platform configuration and on-board workflow requirements for the Arctic, this data model, data pumps and user interfaces were adapted for the ACEX-OffshoreDIS. On the drill ship Vidar Viking the cores were catalogued and petrophysically logged using a GeoTek Multi-Sensor Core Logger System, while further initial measurements, lithological descriptions and biostratigraphic investigations were undertaken on the Oden, which provided laboratory facilities for the expedition. Onboard samples were registered in a corresponding sample archive on both vessels. The ACEX-OffshoreDIS used a local area network covering the two ships of the three icebreaker fleet by wireless LAN between the ships and partly wired LAN on the ships. A DIS-server was installed on each ship. These were synchronized by database replication and linked to a total of 10 client systems and label printers across both ships. The ACEX-OffshoreDIS will also be used for the scientific measurement and analysis phase of the expedition during the post-field operations `shore-party' in November 2004 at the Bremen Core Repository (BCR). The data management system employed in the Arctic will be reconfigured and deployed at the BCR. In addition, an eXtended DIS (XDIS) Web interface will be available. This will allow controlled sample distribution (core curation, sub-sampling) as well as sharing of data (registration, upload and download) with other laboratories which will be undertaking additional sampling and analyses. The OffshoreDIS data management system will be of long-term benefit to both IODP and ICDP, being deployed in forthcoming MSP offshore projects, ICDP lake projects and joint IODP-ICDP projects such as the New Jersey Coastal Plain Drilling Project.

The ICDP Information Network and the Chinese Continental Scientific Drilling CCSD

NASA Astrophysics Data System (ADS)

Conze, R.; Su, D.

2002-12-01

ICDP is an international program investigating the 'System Earth' in multidisciplinary co-operation. Funded drilling projects are characterized by detailed fieldwork at world-class geological sites on the continents and by the global scope of research objectives. During project work, partnering researchers from all over the world work together at remote drill sites and in laboratories at their institutions. Researchers apply a range of highly diverse scientific methodologies, thereby acquiring huge data sets. Multinational co-operation and increasing amounts of scientific data require completely new concepts and practices for scientific work, and place heavy demands on information and communications management. This is achieved by means of the ICDP Information Network. Scientists working on ICDP related data need a central long-term data archive with powerful tools for navigation, data modeling and analysis. The Chinese Continental Scientific Drilling CCSD is a national key scientific and engineering project of the PR China supported by ICDP. The current drill site of CCSD is located in Donghai, Jiangsu Province, the eastern part of the Dabie-Sulu UHP metamorphic belt, which possesses global geological significance. From the spud on June 25, 2001 to April 6, 2002, the 2000m pilot hole was finished with a total core recovery of 88.7% and an average inclination angle of 3-4 degrees. The pilot hole has been transformed to the main hole by hole opening. Deepening and coring of the CCSD-1 main hole is currently in progress. Most of the basic scientific documentation and measurements are done in a large field laboratory directly beside the drill rig, which was set up using the standard of the former German Continental Scientific Drilling (KTB). It includes a powerful infrastructure for computing and electronic communication as well as a comprehensive twofold data and information management: 1. The CCSD-DMIS is a special Data Management Information System for the chinese project management, which is used for internal controlling and decision making. 2. The CCSD-DIS is the specifically designed on-site Drilling Information System, which is used for documentation and archiving of all kinds of scientific and technical information. Both are used in a local Intranet within the field lab, but they also provide certain information via secured Internet services. The CCSD-DIS feeds day-by-day the current reports and new recordings to the CCSD Web portal within the ICDP Information Network (http://www.icdp-online.org/html/sites/donghai/news/news.html). This portal provides chinese and english news and information for the public as well as scientific and technical stuff which is only available for the international CCSD Science Team. Using the example of the CCSD project, a poster and an on-line presentation will show the main components and value-added services of the ICDP Information Network like: ú the common portal for and dissemination of project information by the ICDP Clearinghouse, ú capture of scientific drilling data using individual On-Site Drilling Information Systems (DIS), ú virtual global field laboratories based on eXtended DIS, ú integrated evaluation and analysis of data supported by the ICDP Data Webhouse.

Laser-Mechanical Drilling for Geothermal Energy: Low-Contact Drilling Technology to Enable Economical EGS Wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-01-15

Broad Funding Opportunity Announcement Project: Foro Energy is developing a unique capability and hardware system to transmit high power lasers over long distances via fiber optic cables. This laser power is integrated with a mechanical drilling bit to enable rapid and sustained penetration of hard rock formations too costly to drill with mechanical drilling bits alone. The laser energy that is directed at the rock basically softens the rock, allowing the mechanical bit to more easily remove it. Foro Energy’s laser-assisted drill bits have the potential to be up to 10 times more economical than conventional hard-rock drilling technologies, makingmore » them an effective way to access the U.S. energy resources currently locked under hard rock formations.« less

Marine geology of the Forearc region, southern Mariana Island arc

NASA Astrophysics Data System (ADS)

Karig, D. E.; Ranken, Beverly

The Mariana Arc serves as a type example of an oceanic arc system because of its long history without a continental influence and because of the large suite of data collected from that area. The concentration of deep-sea drilling and related survey data near 18°N has been interpreted in support of subsidence and narrowing of the forearc with time as a result of tectonic erosion. On the contrary, interpretation of a lesser concentration of data from the south end of the arc presented here suggests growth and relative uplift of the lower trench slope. Truncation of all forearc elements occurs south of 13°N, probably as a result of strike slip faulting along east-west fractures that define a transform between the back arc spreading ridge and the trench. North of 13°30'N the inner trench slope is ribbed with ridges that trend parallel to or convex toward the trench. These ridges are largest and perhaps most structurally active at the base of the trench slope. Depositional depth of sediments in Deep Sea Drilling Project holes drilled in the upper slope apron, concave upward slopes of this apron, which trap turbidites, and internal arcward fanning of deeper apron strata are cited in support of relative uplift and arcward rotation of the seaward part of the inner slope and of minor absolute uplift of the sediment apron. This pattern of vertical displacement and rotation, coupled with progressive downlap rather than truncation of apron strata, argues against tectonic erosion and subsidence. The conflicting data may be a result of changing response of the arc over time. Forearc volcanism and tectonic disruption of the basement beneath the upper slope apparently ceased by the early Oligocene. Younger features are more compatible with intermittent accretion of oceanic material, possibly tectonically mixed into the arc basement.

Offshore Tectonics of the St. Elias Mountains: Insights from Ocean Drilling and Seismic Stratigraphy on the Yakutat Shelf

NASA Astrophysics Data System (ADS)

Worthington, L. L.; Gulick, S. P. S.; Montelli, A.; Jaeger, J. M.; Zellers, S.; Walczak, M. H.; Mix, A. C.

2015-12-01

Ongoing collision of the Yakutat (YAK) microplate with North America (NA) in southern Alaska has driven orogenesis of the St. Elias Mountains and the advance of the offshore deformation front to the southeast. The offshore St. Elias fold-thrust belt records the complex interaction between collisional tectonics and glacial climate variability, providing insight for models of orogenesis and the evolution of glacial depocenters. Glacial erosion and deposition have provided sediment that constructed the upper continental shelf, much of which has been reincorporated into the orogenic wedge through offshore faulting and folding. We integrate core and downhole logging data from IODP Expedition 341 (Sites U1420 and U1421) drilled on the Yakutat shelf and slope with high-resolution and regional seismic profiles to investigate the coupled structural and stratigraphic evolution of the St. Elias margin. Site U1420 lies on the Yakutat shelf within the Bering Trough, a shelf-crossing trough that is within primary depocenter for Bering Glacier sediments. Two faults underlie the glacial packages and have been rendered inactive as the depositional environment has evolved, while faulting elsewhere on the shelf has initiated. Site U1421 lies on the current continental slope, within the backlimb of an active thrust that forms part of the modern YAK-NA deformation front. At each of these sites, we recovered glacigenic diamict (at depths up to ~1015 m at Site U1420), much of which is younger than 0.3 Ma. Age models within the trough indicated that initiation of active deformation away from the Bering Trough depocenter likely occurred since 0.3 Ma, suggesting that possible tectonic reorganization due to mass redistribution by glacial processes can occur at time scales on the order of 100kyr-1Myr.

Electrical Properties of the Hanging Wall of the Alpine Fault, New Zealand, from DFDP-2 Wireline Data

NASA Astrophysics Data System (ADS)

Remaud, L.; Doan, M. L.; Pezard, P. A.; Celerier, B. P.; Townend, J.; Sutherland, R.; Toy, V.

2015-12-01

The DFDP-2B borehole drilled at Whataroa, New Zealand, provides a first-hand rare opportunity to investigate the damage pattern next to a major active fault. It was drilled along more than 893 m (820 m TVD) within hanging-wall protomylonites and mylonites. The interval between 264 m and 886 m (measured depth) was intensively investigated by wireline logging. Notably, electrical laterolog data were recorded over almost 3 km of cumulative logs, providing a homogeneous, uniformly sampled recording of the electrical properties of the borehole wall. The laterolog tool measures resistivity with two different electrode configurations, and hence achieves two different depths of penetration. Numerical simulations of the tool's response show that the true resistivity of the rock is close to the deep resistivity measurement, which in DFDP-2 varies between 300 Ω.m and 700 Ω.m. The shallow resistivity is about 75% of this value, as it is more sensitive to the presence of conductive borehole fluid. However, the large borehole diameter (averaging 8.5 inch = or 21.59 cm) only partially explains this value. The strong anisotropy suggested by laboratory measurements on outcrop samples also contributes to the separation between deep and shallow resistivity. The shallow and deep resistivities exhibit many significant drops that are coincident with the presence of fractures detected in borehole televiewer data. More than 700 electrical anomalies have been manually picked. The major ones are correlated with attenuation of the sonic data and sometimes with anomalies in fluid conductivity (temperature and conductivity). Their frequency gradually increases with depth, reaching a plateau below 700 m. This increase with depth may be related to closer proximity to the Alpine Fault.

Stress state and its anomaly observations in the vicinity of a fault in NanTroSEIZE Expedition 322

NASA Astrophysics Data System (ADS)

Wu, Hung-Yu; Saito, Saneatsu; Kinoshita, Masataka

2015-12-01

To better understand the stress state and geological properties within the shallow Shikoku Basin, southwest of Japan, two sites, C0011A and C0011B, were drilled in open-ocean sediments using Logging While Drilling (LWD) and coring, respectively. Resistivity image logging was performed at C0011A from sea floor to 950 m below sea floor (mbsf). At C0011B, the serial coring was obtained in order to determine physical properties from 340 to 880 mbsf. For the LWD images, a notable breakout anomaly was observed at a depth of 615 m. Using resistivity images and a stress polygon, the potential horizontal principal stress azimuth and its magnitude within the 500-750 mbsf section of the C0011A borehole were constrained. Borehole breakout azimuths were observed for the variation by the existence of a fault zone at a depth of 615 mbsf. Out of this fracture zone, the breakout azimuth was located at approximately 109° ± 12°, subparallel to the Nankai Trough convergence vector (300-315°). Our calculations describe a stress drop was determined based on the fracture geometry. A close 90° (73° ± 12°) rotation implied a 100% stress drop, defined as a maximum shear stress drop equal to 1 MPa. The magnitude of the horizontal principal stresses near the fracture stress anomaly ranged between 49 and 52 MPa, and the bearing to the vertical stress (Sv = 52 MPa) was found to be within the normal-faulting stress regime. Low rock strength and a low stress level are necessary to satisfy the observations.

Preliminary report on the geology and geophysics of drill hole UE25a-1, Yucca Mountain, Nevada Test Site

USGS Publications Warehouse

Spengler, Richard W.; Muller, D.C.; Livermore, R.B.

1979-01-01

A subsurface geologic study in connection with the Nevada Nuclear Waste Storage Investigations has furnished detailed stratigraphic and structural information about tuffs underlying northeastern Yucca Mountain on the Nevada Test Site. Drill hole UE25a-1 penetrated thick sequences of nonwelded to densely welded ash-flow and bedded tuffs of Tertiary age. Stratigraphic units that were identified from the drill-hole data include the Tiva Canyon and Topopah Spring Members of the Paintbrush Tuff, tuffaceous beds of Calico Hills, and the Prow Pass and Bullfrog Members of the Crater Flat Tuff. Structural analysis of the core indicated densely welded zones to be highly fractured. Many fractures show near-vertical inclinations and are commonly coated with secondary silica, manganese and iron oxides, and calcite. Five fault zones were recognized, most of which occurred in the Topopah Spring Member. Shear fractures commonly show oblique-slip movement and some suggest a sizable component of lateral compression. Graphic logs are included that show the correlation of lithology, structural properties, and geophysical logs. Many rock units have characteristic log responses but highly fractured zones, occurring principally in the Tiva Canyon and Topopah Spring Members, restricted log coverage to the lower half of the drill hole.

Development and testing of a Mudjet-augmented PDC bit.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Black, Alan; Chahine, Georges; Raymond, David Wayne

2006-01-01

This report describes a project to develop technology to integrate passively pulsating, cavitating nozzles within Polycrystalline Diamond Compact (PDC) bits for use with conventional rig pressures to improve the rock-cutting process in geothermal formations. The hydraulic horsepower on a conventional drill rig is significantly greater than that delivered to the rock through bit rotation. This project seeks to leverage this hydraulic resource to extend PDC bits to geothermal drilling.

Counter-Rotating Tandem Motor Drilling System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kent Perry

2009-04-30

Gas Technology Institute (GTI), in partnership with Dennis Tool Company (DTC), has worked to develop an advanced drill bit system to be used with microhole drilling assemblies. One of the main objectives of this project was to utilize new and existing coiled tubing and slimhole drilling technologies to develop Microhole Technology (MHT) so as to make significant reductions in the cost of E&P down to 5000 feet in wellbores as small as 3.5 inches in diameter. This new technology was developed to work toward the DOE's goal of enabling domestic shallow oil and gas wells to be drilled inexpensively comparedmore » to wells drilled utilizing conventional drilling practices. Overall drilling costs can be lowered by drilling a well as quickly as possible. For this reason, a high drilling rate of penetration is always desired. In general, high drilling rates of penetration (ROP) can be achieved by increasing the weight on bit and increasing the rotary speed of the bit. As the weight on bit is increased, the cutting inserts penetrate deeper into the rock, resulting in a deeper depth of cut. As the depth of cut increases, the amount of torque required to turn the bit also increases. The Counter-Rotating Tandem Motor Drilling System (CRTMDS) was planned to achieve high rate of penetration (ROP) resulting in the reduction of the drilling cost. The system includes two counter-rotating cutter systems to reduce or eliminate the reactive torque the drillpipe or coiled tubing must resist. This would allow the application of maximum weight-on-bit and rotational velocities that a coiled tubing drilling unit is capable of delivering. Several variations of the CRTDMS were designed, manufactured and tested. The original tests failed leading to design modifications. Two versions of the modified system were tested and showed that the concept is both positive and practical; however, the tests showed that for the system to be robust and durable, borehole diameter should be substantially larger than that of slim holes. As a result, the research team decided to complete the project, document the tested designs and seek further support for the concept outside of the DOE.« less

3D Seismic Stratigraphic Analysis of Gas Hydrate Bearing Turbidite Channel-Overbank System in Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Santra, M.; Flemings, P. B.; Scott, E.; Meazell, K.; Petrou, E. G.

2017-12-01

We present a depositional model for a gas hydrate bearing deepwater channel-overbank system in Green Canyon area (around Block 955) in northern Gulf of Mexico. The gas-hydrate bearing reservoir was tested by three wells drilled in 2009 as part of the Gulf of Mexico Gas Hydrate Joint Industry Project (JIP). The same reservoir was sampled during the recent UT-GOM2-1 pressure-coring expedition. Analysis of a newly available wide-azimuth 3D seismic data shows two distinct stages of development of the channel system that significantly impacted the reservoir characteristics. The study area is located near the present-day Green Canyon reentrant, where a succession of Miocene to recent clastic sediments overlies an extensive salt diapir connected to the autochthonous level. The entire supra-salt sedimentary section is intersected by a system of large-scale normal faults formed as a result of salt movement. The channel system containing the gas hydrate reservoir has a well-defined basal surface, and is capped by a channel abandonment surface. Seismic analysis shows at least two distinct phases of channel development. In the first phase, levees undergo progressive gravitational collapse along series of normal faults that dip towards the channel axis. The normal faults on either side of channel axis are linked to a zone of compression located at the channel axis by a decollement surface at the base of the channel. The compression is recorded by bulging and/or thrusting at the channel center. This compressional bulge was eroded at the channel axis. During this phase, no axial channel deposits have been preserved. However, the position of the channel axis is indicated by a prominent linear ridge of fine-grained material that represents the remnant of the compressional bulge. Mapping of gravitational failure surfaces shows significant rotation and displacement of levee deposits along them. The second phase of development of the channel system is marked by the termination of gravitational failure and the preservation of both channel deposits and flanking levees. Both gravitational failure of channel-levee system and large-scale normal faulting impacted hydrate reservoir configuration. The large-scale fault system may have been the major pathway for hydrocarbon migration.

Modeling the Precambrian Topography of Columbia County, Wisconsin Using Two-Dimensional Models of Gravity and Aeromagnetic Data

NASA Astrophysics Data System (ADS)

Rasmussen, J.; Skalbeck, J.; Stewart, E.

2017-12-01

The deep sandstone and dolomite aquifer of Wisconsin is the primary source of water in the central, southern, and western portions of the state, as well as a supplier for many high-capacity wells in the eastern portion. This prominent groundwater system is highly impacted by the underlying Precambrian basement, which includes the doubly plunging Baraboo Syncline in Columbia and Sauk Counties. This project is a continuation of previous work done in Dodge and Fond du Lac Counties by the University of Wisconsin-Parkside (UW-P) and the Wisconsin Geological & Natural History Survey (WGNHS). The goal of this project was to produce of an updated Precambrian topographic map of southern Wisconsin, by adding Gravity and Aeromagnetic data to the existing map which is based mainly on sparse outcrop and well data. Gravity and Aeromagnetic data from the United States Geological Survey (USGS) was processed using GM-SYS 3D modeling software in Geosoft Oasis Montaj. Grids of subsurface layers were created from the data and constrained by well and drilling records. The Columbia County basement structure is a complex network of Precambrian granites and rhyolites which is non-conformably overlain by quartzite, slate, and a layer of iron rich sedimentary material. Results from previously collected cores as well as drilling done in neighboring Dodge County, show that the iron rich layer was draped over much of the Baraboo area before being subject to the multitude of folding and faulting events that happened in the region during the late Precambrian. This layer provides telltale signatures that aided in construction of the model due to having an average density of 3.7 g/cm3 and a magnetic susceptibility of 8000 x 10-6 cgs, compared to the average density and susceptibility of the rest of the bedrock being 2.8 g/cm3 and 1500 x 10-6 cgs, respectively. The research done on the Columbia County basement is one part of a larger project aimed at improving groundwater management efforts of the primary aquifer in central, southern, and western Wisconsin.

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas

DOEpatents

McCormick, S.H.; Pigott, W.R.

1997-12-30

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area. 3 figs.

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas

DOEpatents

McCormick, Steve H.; Pigott, William R.

1997-01-01

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area.

The Great California ShakeOut: Science-Based Preparedness Advocacy

NASA Astrophysics Data System (ADS)

Benthien, M. L.

2009-12-01

The Great Southern California ShakeOut in November 2008 was the largest earthquake drill in U.S. history, involving over 5 million southern Californians through a broad-based outreach program, media partnerships, and public advocacy by hundreds of partners. The basis of the drill was a comprehensive scenario for a magnitude 7.8 earthquake on the southern San Andreas fault, which would cause broad devastation. In early 2009 the decision was made to hold the drill statewide on the third Thursday of October each year (October 15 in 2009). Results of the 2008 and 2009 drills will be shared in this session. In addition, prospects of early warning systems will be described, that will one day provide the needed seconds before strong shaking arrives in which critical systems and be shut down, and people can do what they've been practicing in the ShakeOut drills: drop, cover, and hold on. A key aspect of the ShakeOut is the integration of a comprehensive earthquake scenario (incorporating earth science, engineering, policy, economics, public health, and other disciplines) and the lessons learned from decades of social science research about why people get prepared. The result is a “teachable moment” on par with having an actual earthquake (often followed by increased interest in getting ready for earthquakes). ShakeOut creates the sense of urgency that is needed for people, organizations, and communities to get prepared, to practice what to do to be safe, and to learn what plans need to be improved.

Geometry and kinematics of the Triassic rift basin in Jameson Land (East Greenland)

NASA Astrophysics Data System (ADS)

Guarnieri, Pierpaolo; Brethes, Anaïs.; Rasmussen, Thorkild M.

2017-04-01

The Triassic rift basin along the east Greenland margin described in this paper is represented by NE-SW trending basins and highs segmented by NW-SE trending transfer zones. Coarse-grained sediments along the eastern side of Jameson Land are shown to be hosted in half-graben structures belonging to the Carlsberg Fjord Basin that is bounded by NW dipping normal faults mapped and described after fieldwork in the Klitdal area in Liverpool Land. New aeromagnetic and electromagnetic data together with new drill cores allow the reinterpretation of available seismic lines showing the continuation of the Triassic rift basin toward the SW where it is buried under the Upper Triassic postrift sediments and the Jurassic successions of the Jameson Land Basin. The N-S trending Liverpool Land, interpreted as the boundary block of the Triassic basin, is shown to represent a structural high inherited from the Late Carboniferous tectonics and faulted during the Triassic rifting. The Carlsberg Fjord Basin and the Klitdal Fault System described in this paper should be seen as analogues to the Helgeland Basin in the Norwegian offshore that is bounded by the Ylvingen Fault Zone and to the Papa and West of Shetlands Basins that are bounded by the Spine Fault. The Triassic rift zone and transfer faults on both conjugate margins show a straightforward correlation with the trends of the initial spreading line and fracture zones of the northeast Atlantic indicating a possible inheritance of the Triassic rifting.

An IODP proposal to drill the Godzilla Megamullion as a step to Mohole

NASA Astrophysics Data System (ADS)

Ohara, Y.; Michibayashi, K.; Dick, H. J. B.; Snow, J. E.; Ono, S.

2017-12-01

The year 2017 represents the 60th anniversary of the "original" project Mohole, which was coined by Walter Munk in 1957. Although the project Mohole has not yet been realized, the hard-rock community is now striving hard to understand the upper mantle in a variety of ways. Firstly, the present-day project Mohole, M2M (Moho-to-Mantle) project, will move forward in this September, conducting multi-channel seismic profiling off Hawaii as a site survey. Oman Drilling Project has started last December, and the drilled cores are being described aboard D/V Chikyu from July, this year. Furthermore, the forearc M2M proposal to drill the Bonin Trench forearc mantle was submitted to IODP in April 2016. Being a part of these efforts, we are preparing an IODP proposal to drill the Godzilla Megamullion, the largest known oceanic core complex on the Earth, located in the Parece Vela Basin in the Philippine Sea. A significant fraction of the ocean floor is created in backarc basins, while there have been no single long core of backarc basin lower ocean crust, from which to understand the likely differences in magmatic evolution and crustal structure in this key setting. The opportunity to explore the formation of the backarc basin lower crust and upper mantle is, therefore, an important contribution to understanding the ocean basins. At the same time, a better understanding of the architecture of backarc basin lower crust and upper mantle will greatly aid in the interpretation of the results of ophiolite study, since much of our understanding of the architecture of oceanic lower crust and upper mantle comes from ophiolites, most of which are thought to have at least some arc and/or backarc component. The Godzilla Megamullion is unique in its huge size as well as its development in a backarc basin, a rare tectonic window to study backarc basin lithosphere. The Godzilla Megamullion is prepared for full drilling proposal, with complete bathymetric data, multiple bottom samplings, and multi-channel seismic profilings as well as P-wave velocity structures. We will propose substantial riserless drilling at Godzilla Megamullion that will provide an excellent opportunity to understand backarc basin lower crust and upper mantle. In this contribution, we will make use of this opportunity to share the general scheme of the proposal with the community.

Structural controls of the Tuscarora geothermal field, Elko County, Nevada

NASA Astrophysics Data System (ADS)

Dering, G.; Faulds, J. E.

2012-12-01

Tuscarora is an amagmatic geothermal system located ~90 km northwest of Elko, Nevada, in the northern part of the Basin and Range province ~15 km southeast of the Snake River Plain. Detailed geologic mapping, structural analysis, and well data have been integrated to identify the structural controls of the Tuscarora geothermal system. The structural framework of the geothermal field is defined by NNW- to NNE-striking normal faults that are approximately orthogonal to the present extension direction. Boiling springs, fumaroles, and siliceous sinter emanate from a single NNE-striking, west-dipping normal fault. Normal faults west of these hydrothermal features mostly dip steeply east, whereas normal faults east of the springs primarily dip west. Thus, the springs, fumaroles, and sinter straddle a zone of interaction between fault sets that dip toward each other, classified as a strike-parallel anticlinal accommodation zone. Faults within the geothermal area are mostly discontinuous along strike with offsets of tens to hundreds of meters, whereas the adjacent range-bounding fault systems of the Bull Run and Independence Mountains accommodate several kilometers of displacement. The geothermal field lies within a broad step over between the southward terminating west-dipping Bull Run fault zone and the northward terminating west-dipping Independence Mountains fault zone. Neither of these major fault zones is known to host high temperature geothermal systems. The accommodation zone lies within the broad step over and contains both east-dipping antithetic and west-dipping synthetic faults. Accommodation zones are relatively common structural components of extended terranes that transfer strain between oppositely dipping fault sets via a network of subsidiary normal faults. This study has identified the hinge zone of an anticlinal accommodation zone as the site most conducive to fluid up-flow. The recognition of this specific portion of an accommodation zone as a favorable structural setting for geothermal activity may be a useful exploration tool for development of drilling targets in extensional terranes, as well as for developing geologic models of known geothermal fields. This type of information may ultimately help to reduce the risks of targeting successful geothermal wells in such settings.

Garden Banks 388 subsea drilling/production template: Project management of a fast-track project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ledbetter, W.R.

1995-10-01

Enserch Exploration`s Garden Banks 388 development is a production scheme based around a floating drilling and production facility and subsea drilling/production template. The Floating Production Facility (FPF) is a converted semisubmersible drilling rig which will drill and product through a 24-well slot template. This development is located in Block 388 of the Garden Banks area in the Gulf of Mexico approximately 200 miles southwest of New Orleans. Louisiana. This production system is being installed in an area of known oil and gas reserves and will produce to a shallow water platform 54 miles away at Ewing Bank 315. The FPFmore » will be permanently moored on the surface above the template. The subsea template has been installed in 2,190 feet of water and will produce through a 2,000 foot free-standing production riser system to the FPF. The produced fluids are partially separated on the FPF before oil and gas are pumped through the template to export gathering lines which are connected to the shallow water facility.« less

Gravity Survey of the Carson Sink - Data and Maps

DOE Data Explorer

Faulds, James E.

2013-12-31

A detailed gravity survey was carried out for the entire Carson Sink in western Nevada (Figure 1) through a subcontract to Zonge Engineering, Inc. The Carson Sink is a large composite basin containing three known, blind high-temperature geothermal systems (Fallon Airbase, Stillwater, and Soda Lake). This area was chosen for a detailed gravity survey in order to characterize the gravity signature of the known geothermal systems and to identify other potential blind systems based on the structural setting indicated by the gravity data. Data: Data were acquired at approximately 400, 800, and 1600 meter intervals for a total of 1,243 stations. The project location and station location points are presented in Figure 14. The station distribution for this survey was designed to complete regional gravity coverage in the Carson Sink area without duplication of available public and private gravity coverage. Gravity data were acquired using a Scintrex CG-5 gravimeter and a LaCoste and Romberg (L&R) Model-G gravimeter. The CG-5 gravity meter has a reading resolution of 0.001 milligals and a typical repeatability of less than 0.005 milligals. The L&R gravity meter has a reading resolution of 0.01 milligals and a typical repeatability of 0.02 milligals. The basic processing of gravimeter readings to calculate through to the Complete Bouguer Anomaly was made using the Gravity and Terrain Correction software version 7.1 for Oasis Montaj by Geosoft LTD. Results: The gravity survey of the Carson Sink yielded the following products. Project location and station location map (Figure 14). Complete Bouguer Anomaly @ 2.67 gm/cc reduction density. Gravity Complete Bouguer Anomaly at 2.50 g/cc Contour Map (Figure 15). Gravity Horizontal Gradient Magnitude Shaded Color Contour Map. Gravity 1st Vertical Derivative Color Contour Map. Interpreted Depth to Mesozoic Basement (Figure 16), incorporating drill-hole intercept values. Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south-central, east-central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step-overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.

Comparison of conventional and self-consolidating concrete for drilled shaft construction.

DOT National Transportation Integrated Search

2015-04-01

Many entities currently use self-consolidating concrete (SCC), especially for drilled shaft construction. This project investigated the use of SCC : and various test methods to assess the suitability of SCC in underwater placement conditions. Eight m...

Superhot Drilling in Iceland, the Experience of the Iceland Deep Drilling Project.

NASA Astrophysics Data System (ADS)

Elders, W. A.; Friðleifsson, G. Ó.; Zierenberg, R. A.; Fowler, A. P.

2017-12-01

The Iceland Deep Drilling Project aims to improve geothermal economics by producing supercritical fluids (www.iddp.is). Supercritical wells could yield an order of magnitude more usable energy than that from conventional geothermal wells because of higher enthalpy and enhanced flow properties. In 2009, the IDDP-1 well failed to reach supercritical conditions in the Krafla caldera in NE Iceland, after encountering rhyolite magma at only 2.1 km depth. The completed geothermal well became the world's hottest and produced superheated steam with a wellhead temperature of 452°C and flow sufficient to generate 35 MWe. The IDDP next moved SW to the Reykjanes Peninsula, the landward extension of the Mid-Atlantic Ridge, where it is possible to study an analog of the roots of a black smoker. Reykjanes is unique among Icelandic geothermal systems in being recharged by seawater, which has a critical point of 406°C at 298 bars. Drilling began by deepening an existing 2.5 km deep production well to 3 km depth, and then angling it towards the main upflow zone of the system, for a total slant depth of 4,659 m. Total circulation losses were encountered below 3 km that could not be cured by lost circulation materials or by multiple cement jobs. Accordingly, drilling continued to total depth without return of drill cuttings. We attempted 13 core runs below 3 km depth, only half of which recovered core. The cores are basalts and dolerites with alteration ranging from lower greenschist facies to lower amphibolite facies, suggesting formation temperatures >450°C. After the end of drilling in January 2017, following only six days of heating, supercritical conditions (426°C at 340 bars) were measured in the well at a depth of 4.5 km. The well has not yet been allowed to equilibrate to full in situ temperature. A perforated liner was inserted to 4,570 m, depth to facilitate temperature cycling to enhance permeability at depth through thermal cracking. In 2018 this will be followed by a flow test and eventual production of the well. The project is co-funded by the DEEPEGS project (EU H2020), HS Orka (the field operator), Statoil, the IDDP consortium, and the ICDP. Planning is underway to drill IDDP-3 at Hellisheidi.

Some New Constraints On The Stratigraphic And Structural Setting Of The Soda Lake Geothermal Field, Churchill County, Nevada - McLACHLAN, Holly S. and FAULDS, James E., Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV 89557

NASA Astrophysics Data System (ADS)

McLachlan, H. S.

2012-12-01

Our research group is currently conducting a regional survey to identify favorable structural settings of producing and prospective geothermal fields in the Great Basin. The Soda Lake geothermal field - one of the oldest consistently producing fields in this study region - is located in west-central Nevada near the heart of the Carson Sink. Producing and prospective geothermal fields in the surrounding highlands are hosted in 1) fault termination zones (Desert Queen), 2) accommodation zones (Brady's Hot Springs) and 3) fault step-overs (Desert Peak). However, the structural setting is challenging to identify at the Soda Lake field, because it lies in the central part of a large basin with no nearby bedrock exposures. The well field at Soda Lake is centered ~3.5 km NNE of the Holocene Soda Lake maar, from which it takes its name. The geothermal field was identified serendipitously during the drilling of an irrigation survey well in the early 20th century. Modern exploratory drilling at the field began in the mid-1970s and has continued sporadically to the present. There are currently more than 28 500+ m wells at and near the production site. The exceptional drilling density at Soda Lake allows for comparatively reliable correlation of stratigraphy in the subsurface below the feature-poor Carson Sink. Stratigraphy in the Soda Lake geothermal area is relatively "layer cake" at the scale of the well field. Unconsolidated sediments extend more than 1000 m below surface. The upper few hundred meters are composed of fluvial and lacustrine sediments derived from Sierran batholith source rocks. The deeper basin fill derives from more proximal mafic to felsic Miocene volcanic rocks along the basin margins. At ~450-650 m depth, basin sediments are interrupted by a 5.11 Ma trachytic basalt of restricted lateral extent and variable thickness. Most wells intercept ~50-250 m of fine lacustrine sediments below this basalt body before intercepting the basin floor. Basin floor rocks consist of a thick (>1500 m) package of fine-grained altered basalts and interbedded sedimentary rocks. Within this package, in the central portion of the well field, a ~300-500 m thick marker of laminated siltstones + coarse-grained, porphyritic plagioclase basalt has been identified in cuttings. Variations in thickness within the marker suggest older faults with significant throw were primarily northwest striking. Large local variations in the thickness of the 5.11 Ma trachytic basalt body support this interpretation and indicate NW-striking faulting likely continued through ~5 Ma B.P. However, all evidence indicates near-surface (<1000 m depth) faults at the Soda Lake geothermal field strike NNE, perpendicular to the contemporary extension direction. Structural interpretation is in progress for the Soda Lake geothermal field. In conjunction with recently obtained 3D seismic and microgravity surveys, stratigraphic information obtained from cuttings broadly constrains the structural setting. These data may permit determination of the specific structural host environment and should allow for assessment of how the prevailing faults at the site correlate with regional scale trends.

Localized Deformation Beginning more than 15 km Beneath the Mid-Atlantic Ridge, 14 to 16 N

NASA Astrophysics Data System (ADS)

Kelemen, P.

2003-12-01

ODP Leg 209 drilled 19 holes at 8 sites along the Mid-Atlantic Ridge from 14° 43 to 15° N. All sites were surveyed by submersible, and chosen to be < 200 m from peridotite or dunite exposed on the seafloor; outcrops of gabbroic rock were also close to some sites. One of our primary goals was to constrain the mechanism of mantle upwelling, corner flow and exhumation of shallow mantle rocks. Drilling at Sites 1268, 1270-72, 1274 and 1275 penetrated 1075 meters, and recovered 354 m of core. At Sites 1268 and 1270-72 we recovered 25% gabbroic rocks and 75% residual mantle peridotite. Core from Site 1274 was mainly residual peridotite, while core from Site 1275 was mainly gabbroic. Most of the residual peridotites have nearly undeformed, protogranular textures. Orthopyroxenes are interstitial to olivine or even poikilitic. Rare, isolated clinopyroxene grains are also interstitial. Skeletal spinel grains have mm-scale extensions in three dimensions, with no discernable shape fabric. These textures are clearly different from porphyroclastic textures typical in ophiolites and fracture zone dredges. As described elsewhere at this meeting, impregnated peridotites contain olivine, 2 pyroxenes, plagioclase and spinel, and equilibrated at 0.54 GPa (+/-0.14 GPa, 2σ ) and 1220° C (+/-16° C, 2σ ) [Kinzler & Grove, JGR 92]. Melts entered the thermal boundary layer beneath the Mid-Atlantic Ridge at about 20 km [e.g., Sleep, JGR 75; Reid & Jackson, MGR 82; Grove et al JGR 92; Cannat JGR 96; Michael & Chase CMP 97; Braun et al., EPSL 00], and began to crystallize within impregnated peridotites and as discrete plutons intruding peridotite. Gabbroic rocks and peridotites from most sites underwent large tectonic rotations since aquiring remanent magnetization. At some sites, rotations may have exceeded 60° around near-horizontal axes parallel to the Mid-Atlantic Ridge. Such large rotations are unlikely to have been accomodated along a single fault, and instead blocks were progressively rotated along a series of fault systems. Sites 1270 (25% gabbroic) and 1275 (75% gabbroic) were drilled into large, low angle fault surfaces previously identified as oceanic core complexes. Deformation at Site 1270 is similar to most other Sites, while core from Site 1275 is the most weakly deformed. However, high pressure igneous assemblages indicate that some Site 1275 rocks were exhumed from depths of 20 km or more, as were residual peridotites at the other Sites. At all sites except 1269, 1273 and 1275, we recovered high temperature mylonitic shear zones (mainly with impregnated peridotite mineralogy, but also mylonitic gabbros), and intervals of low temperature fault gouge. Shear zones and faults are not all parallel; numerous, cross-cutting planes of localized deformation formed at > 1000° C to < 100° C, from > 15 km depth to near the seafloor. These accommodated nearly all subsolidus deformation during corner flow and exhumation of residual peridotites (plus high pressure igneous rocks), in keeping with the inference that the thermal boundary layer in this region extends to at least 20 km. Penetrative, viscous deformation of blocks between shear zones and faults was minor. If this is a general process at slow-spreading ridges, then one would predict that shallow mantle anisotropy in the Atlantic would be less pronounced than in the Pacific, consistent with recent seismic data [FAIM Experiment, Gaherty, Collins et al, this session].

Reconnaissance geology of the Jabal Dalfa Quadrangle, sheet 21/43 C, Kingdom of Saudi Arabia

USGS Publications Warehouse

Greene, Robert C.

1983-01-01

The Jabal Dalfa quadrangle (sheet 21/43 C) is part of the Najd province in west-central Saudi Arabia. The quadrangle is mostly a plain, tilted gently northeastward, but local inselbergs and two areas of dissected uplands rise as much as 200 m above the plain. Wadi Bishah and Wadi Ranyah terminate in the quadrangle. The quadrangle is underlain by Precambrian metavolcanic, metasedimentary, and plutonic rocks. The gneiss outcrops in the northeast and east-central parts of the quadrangle are apparently the oldest rocks. After they were emplaced, a wide variety of metavolcanic and metasedimentary rocks were deposited at Jabal Dalfa and Umm Shat, and in the northeast part of the quadrangle as the Arfan formation. Subsequently, granite gneiss was emplaced in the west part of the quadrangle and intruded by gabbro. Metabasalt and meta-andesite were extruded in a wide north-trending belt through the middle of the quadrangle and at Jabal Silli. Intrusion of small bodies of granitic rocks and Najd faulting conclude the Precambrian history of the area. Surficial deposits include sand and gravel covering the plains, alluvial fans, and voluminous dune sands. In the southeast part of the quadrangle, the layered rocks strike north and dip steeply. They are oriented parallel to the Nabitah fault zone. In the northeast and east-central parts of the quadrangle, layered rocks and gneiss are sheared into slices by the southernmost faults of the major Najd fault zone. Bedding and foliation in these slices strike northwest, parallel to the faults. Gneiss in the west part of the quadrangle also strikes northwest, and dips steeply to vertically; layered rocks underlying Jabal Silli strike northeast. Layered metamorphic rocks in the Jabal Dalfa quadrangle are mostly in the greenschist facies. Projection of data from other quadrangles suggests that the oldest gneiss is about 780 Ma old and the Arfan formation, Umm Shat, and Jabal Dalfa layered rocks are about 775 to 745 Ma old. The gneiss of Shaib Hadhaq is probably about 720 Ma old, the gabbro is 640 to 625 Ma old, and the granite is about 600 Ma old. The airborne magnetometer survey suggests that considerable additional gabbro underlies the west part of the quadrangle. Concealed serpentinite bodies, particularly in the Nabitah fault zone, are also suggested. Elongate anomalies and linear gradients indicate that the northeast part of the quadrangle is probably part of the Najd fault zone. A number of gold-bearing quartz veins in the quadrangle were mined in ancient times, and on, at Jabal Umm Matirah has been drilled and found to be uneconomic. A nickel-copper prospect has proved uneconomic. geochemical survey for additional deposits of metals was completed in 1982.

Physical exploration for uranium during 1951 in the Silver Reef district, Washington County, Utah

USGS Publications Warehouse

Stugard, Frederick

1954-01-01

During 1951 a joint exploration program of the most promising uraniferous areas in the Silver Reef district was made by the U.S. Geological Survey and the U.S. atomic Energy Commission. A U.S. Bureau of Mines drill crew, on contract to the Atomic Energy Commission, did 2,450 feet of diamond drilling under the geological supervision of the U.S. Geological Survey. The purpose of the drilling was to delineate broadly the favorable ground for commercial development of the uranium deposits. Ten drill holes were located around Pumpkin Point, which is the northeastern end of Buckeye Reef, to probe for extensions of small ore sheets mined on the Point in fine-grained sandstones of the Chinle formation. Three additional holes were located around Tecumseh Hill to probe for extensions of the small showings of uranium-bearing rocks of Buckeye Reef. Only one trace of uranium mineral was detected in the 13 drill holes by logging of drill cores, gamma-ray logging of the holes, and analysis of many core splits from favorable lithology. Extensive traversing with Geiger counters throughout the district and detailed geologic mapping of areas on Buckeye Reef and on East Reef indicate that the chances of discovering significant uranium deposits in the Silver Reef district are very poor, because of: highly variable lithology, closely faulted structure, and obliteration of the shallow uranium-bearing lenses by silver mining. Most of the available ore in the district was in the Pumpkin Point area and has been mined during 1950 to 1953. No ore reserves can be computed for the district before further development work. The most favorable remaining area in the district is now being explored by the operators with Atomic Energy Commission supervision.

Remote drill bit loader

DOEpatents

Dokos, J.A.

1997-12-30

A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. 5 figs.

Remote drill bit loader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokos, James A.

A drill bit loader for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotationmore » of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned.« less

Remote drill bit loader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokos, J.A.

A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pinsmore » prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. 5 figs.« less

Geotechnical Properties of Periplatform Carbonate Sediments

DTIC Science & Technology

1990-07-01

and Atmospheric and geoacoustic parameters for similar sediments in Research Laboratory participated in Ocean Drilling other regions. Leg 101. During...this exercise sha’"w-water and midwater depth carbonate sediments from a few deep drill holes were studied extensively by Results and Recommendations...protected by the grains and are less Deep Sea Drilling Project Leg 86. In: Heath, G. R., affected by consolidation than they are in matrix- Bruckle, L. H

Temperature distribution in the Cerro Prieto geothermal field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castillo B, F.; Bermejo M, F.J.; Domiguez A, B.

1981-01-01

A series of temperature and pressure logs and flow rate measurements was compiled for each of the geothermal wells drilled to different reservoir depths between October 1979 and December 1980. Based on the valuable information obtained, a series of graphs showing the thermal characteristics of the reservoir were prepared. These graphs clearly show the temperature distribution resulting from the movement of fluids from the deep regions toward the higher zones of the reservoir, thus establishing more reliable parameters for locating new wells with better production zones. Updated information based on data from new deep wells drilled in the geothermal fieldmore » is presented here. This new information does not differ much from earlier estimates and theories. However, the influence of faulting and fracturing on the hydrothermal recharge of the geothermal reservoir is seen more clearly.« less

Drilled Shaft Foundations for Noise Barrier Walls and Slope Stabilization

DOT National Transportation Integrated Search

2002-12-01

This research project is focused on two primary objectives. The first objective relates to the development of a methodology for using the SPT (Standard Penetration Test) results to design the laterally loaded drilled shafts. The second objective aims...

Instrumentation for measurements of lateral Earth pressure in drilled shafts.

DOT National Transportation Integrated Search

1968-09-01

This project involves the design, construction, and testing in the : laboratory and field of instrumentation capable of measuring the lateral : earth pressure along a drilled shaft. : A good deal of work" has been done concerning the development of p...

WETTABILITY AND PREDICTION OF OIL RECOVERY FROM RESERVOIRS DEVELOPED WITH MODERN DRILLING AND COMPLETION FLUIDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jill S. Buckley; Norman r. Morrow

2002-06-01

This first semiannual report covers efforts to select the materials that will be used in this project. Discussions of crude oils, rocks, smooth mineral surfaces, and drilling mud additives are included in this report.

Ejector subassembly for dual wall air drilling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolle, J.J.

1996-09-01

The dry drilling system developed for the Yucca Mountain Site Characterization Project incorporates a surface vacuum system to prevent drilling air and cuttings from contaminating the borehole wall during coring operations. As the drilling depth increases, however there is a potential for borehole contamination because of the limited volume of air which can be removed by the vacuum system. A feasibility analysis has shown that an ejector subassembly mounted in the drill string above the core barrel could significantly enhance the depth capacity of the dry drilling system. The ejector subassembly would use a portion of the air supplied tomore » the core bit to maintain a vacuum on the hole bottom. The results of a design study including performance testing of laboratory scale ejector simulator are presented here.« less

White Sands Missile Range Main Cantonment and NASA Area Faults, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, Greg

This is a zipped ArcGIS shapefile containing faults mapped for the Tularosa Basin geothermal play fairway analysis project. The faults were interpolated from gravity and seismic (NASA area) data, and from geomorphic features on aerial photography. Field work was also done for validation of faults which had surface expressions.

The Detection Method of Fire Abnormal Based on Directional Drilling in Complex Conditions of Mine

NASA Astrophysics Data System (ADS)

Huijun, Duan; Shijun, Hao; Jie, Feng

2018-06-01

In the light of more and more urgent hidden fire abnormal detection problem in complex conditions of mine, a method which is used directional drilling technology is put forward. The method can avoid the obstacles in mine, and complete the fire abnormal detection. This paper based on analyzing the trajectory control of directional drilling, measurement while drilling and the characteristic of open branch process, the project of the directional drilling is formulated combination with a complex condition mine, and the detection of fire abnormal is implemented. This method can provide technical support for fire prevention, which also can provide a new way for fire anomaly detection in the similar mine.

A new drilling method-Earthworm-like vibration drilling.

PubMed

Wang, Peng; Ni, Hongjian; Wang, Ruihe

2018-01-01

The load transfer difficulty caused by borehole wall friction severely limits the penetration rate and extended-reach limit of complex structural wells. A new friction reduction technology termed "earthworm-like drilling" is proposed in this paper to improve the load transfer of complex structural wells. A mathematical model based on a "soft-string" model is developed and solved. The results show that earthworm-like drilling is more effective than single-point vibration drilling. The amplitude and frequency of the pulse pressure and the installation position of the shakers have a substantial impact on friction reduction and load transfer. An optimization model based on the projection gradient method is developed and used to optimize the position of three shakers in a horizontal well. The results verify the feasibility and advantages of earthworm-like drilling, and establish a solid theoretical foundation for its application in oil field drilling.

Illite authigenesis during faulting and fluid flow - a microstructural study of fault rocks

NASA Astrophysics Data System (ADS)

Scheiber, Thomas; Viola, Giulio; van der Lelij, Roelant; Margreth, Annina

2017-04-01

Authigenic illite can form synkinematically during slip events along brittle faults. In addition it can also crystallize as a result of fluid flow and associated mineral alteration processes in hydrothermal environments. K-Ar dating of illite-bearing fault rocks has recently become a common tool to constrain the timing of fault activity. However, to fully interpret the derived age spectra in terms of deformation ages, a careful investigation of the fault deformation history and architecture at the outcrop-scale, ideally followed by a detailed mineralogical analysis of the illite-forming processes at the micro-scale, are indispensable. Here we integrate this methodological approach by presenting microstructural observations from the host rock immediately adjacent to dated fault gouges from two sites located in the Rolvsnes granodiorite (Bømlo, western Norway). This granodiorite experienced multiple episodes of brittle faulting and fluid-induced alteration, starting in the Mid Ordovician (Scheiber et al., 2016). Fault gouges are predominantly associated with normal faults accommodating mainly E-W extension. K-Ar dating of illites separated from representative fault gouges constrains deformation and alteration due to fluid ingress from the Permian to the Cretaceous, with a cluster of ages for the finest (<0.1 µm) fraction in the early to middle Jurassic. At site one, high-resolution thin section structural mapping reveals a complex deformation history characterized by several coexisting types of calcite veins and seven different generations of cataclasite, two of which contain a significant amount of authigenic and undoubtedly deformation-related illite. At site two, fluid ingress along and adjoining the fault core induced pervasive alteration of the host granodiorite. Quartz is crosscut by calcite veinlets whereas plagioclase, K-feldspar and biotite are almost completely replaced by the main alteration products kaolin, quartz and illite. Illite-bearing micro-domains were physically separated by means of microsawing and drilling devices. K-Ar and XRD data from these separates are compared with bulk K-Ar and XRD data from the adjacent fault gouges, which may help to further unravel complex histories archived in multiply activated brittle fault zones. Scheiber, T., Viola, G., Wilkinson, C.M., Ganerød, M., Skår, Ø., and D. Gasser (2016): Direct 40Ar/39Ar dating of Late-Ordovician and Silurian brittle faulting in the southwestern Norwegian Caledonides. Terra Nova 28, 374-382.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, Michael

Geomechanics Technologies has completed a detailed characterization study of the Wilmington Graben offshore Southern California area for large-scale CO₂ storage. This effort has included: an evaluation of existing wells in both State and Federal waters, field acquisition of about 175 km (109 mi) of new seismic data, new well drilling, development of integrated 3D geologic, geomechanics, and fluid flow models for the area. The geologic analysis indicates that more than 796 MMt of storage capacity is available within the Pliocene and Miocene formations in the Graben for midrange geologic estimates (P50). Geomechanical analyses indicate that injection can be conducted withoutmore » significant risk for surface deformation, induced stresses or fault activation. Numerical analysis of fluid migration indicates that injection into the Pliocene Formation at depths of 1525 m (5000 ft) would lead to undesirable vertical migration of the CO₂ plume. Recent well drilling however, indicates that deeper sand is present at depths exceeding 2135 m (7000 ft), which could be viable for large volume storage. For vertical containment, injection would need to be limited to about 250,000 metric tons per year per well, would need to be placed at depths greater than 7000ft, and would need to be placed in new wells located at least 1 mile from any existing offset wells. As a practical matter, this would likely limit storage operations in the Wilmington Graben to about 1 million tons per year or less. A quantitative risk analysis for the Wilmington Graben indicate that such large scale CO₂ storage in the area would represent higher risk than other similar size projects in the US and overseas.« less

An Investigation of the Mass Balance of Oil and Gas Produced Versus Estimated Reserves Remaining within the A.W.P. Field, McMullen County, Texas

NASA Astrophysics Data System (ADS)

Hamilton, Scott Murphy

The A.W.P. Field is located in McMullen County, approximately 4 to 6 miles southeast of the town of Tilden in the Rio Grande Embayment. The study area was believed to be near depletion of all hydrocarbons; however, a recent well drilled (fall 2014) just to the west of the study area has produced significant hydrocarbons. This prompted Milagro Exploration to launch an effort to reevaluate the potential within the field in order to investigate whether the field is, in fact, entirely depleted. My approach to solving this problem began with researching the area to develop an understanding of the geological setting, depositional systems, and productive intervals, then acquiring the proper data, as this data was the foundation of the project. I completed a detailed correlation framework of key formations with the acquired well logs. I interpreted an extensive 3D seismic data set to map my areas of interest and faults. With all relevant information, I completed structure maps, isopach maps, production maps, and calculated volumetrics, concluding with my recommendation, and determined whether the field is ultimately depleted or not. I concluded that there are two relevant intervals within the study area. First, the Wilcox-Wales Formation (Wales; Early Tertiary) was a random stratigraphic accumulation that had sporadic hydrocarbon production, and would be essentially high risk to drill. Second, the Olmos Formation (Olmos; Late Cretaceous) had significant potential for 2 horizontal wells on the western side of the lease area.

Stratigraphy and tectonic history of the Tucson Basin, Pima County, Arizona, based on the Exxon state (32)-1 well

USGS Publications Warehouse

Houser, Brenda B.; Peters, Lisa; Esser, Richard P.; Gettings, Mark E.

2004-01-01

The Tucson Basin is a relatively large late Cenozoic extensional basin developed in the upper plate of the Catalina detachment fault in the southern Basin and Range Province, southeastern Arizona. In 1972, Exxon Company, U.S.A., drilled an exploration well (Exxon State (32)-1) near the center of the Tucson Basin that penetrated 3,658 m (12,001 ft) of sedimentary and volcanic rocks above granitoid basement. Detailed study of cuttings and geophysical logs of the Exxon State well has led to revision of the previously reported subsurface stratigraphy for the basin and provided new insight into its depositional and tectonic history. There is evidence that detachment faulting and uplift of the adjacent Catalina core complex on the north have affected the subsurface geometry of the basin. The gravity anomaly map of the Tucson Basin indicates that the locations of subbasins along the north-trending axis of the main basin coincide with the intersection of this axis with west-southwest projections of synforms in the adjacent core complex. In other words, the subbasins overlie synforms and the ridges between subbasins overlie antiforms. The Exxon State well was drilled near the center of one of the subbasins. The Exxon well was drilled to a total depth of 3,827 m (12,556 ft), and penetrated the following stratigraphic section: Pleistocene(?) to middle(?) Miocene upper basin-fill sedimentary rocks (0-908 m [0-2,980 ft]) lower basin-fill sedimentary rocks (908-1,880 m [2,980-6,170 ft]) lower Miocene and upper Oligocene Pantano Formation (1,880-2,516 m [6,170-8,256 ft]) upper Oligocene to Paleocene(?) volcanic and sedimentary rocks (2,516-3,056 m [8,256-10,026 ft]) Lower Cretaceous to Upper Jurassic Bisbee Group (3,056-3,658 m [10,026-12,001 ft]) pre-Late Jurassic granitoid plutonic rock (3,658-3,827 m [12,001- 12,556 ft]). Stratigraphy and Tectonic History of the Tucson Basin, Pima County, Arizona, Based on the Exxon State (32)-1 Well The 1,880 m (6,170 ft) of basin-fill sedimentary rocks consist of alluvial-fan, alluvial-plain, and playa facies. The uppermost unit, a 341-m-thick (1,120-ft) lower Pleistocene and upper Pliocene alluvial-fan deposit (named the Cienega Creek fan in this study), is an important aquifer in the Tucson basin. The facies change at the base of the alluvial fan may prove to be recognizable in well data throughout much of the basin. The well data show that a sharp boundary at 908 m (2,980 ft) separates relatively unconsolidated and undeformed upper basin fill from denser, significantly faulted lower basin fill, indicating that there were two stages of basin filling in the Tucson basin as in other basins of the region. The two stages apparently occurred during times of differing tectonic style in the region. In the Tucson area the Pantano Formation, which contains an andesite flow dated at about 25 Ma, fills a syntectonic basin in the hanging wall of the Catalina detachment fault, reflecting middle Tertiary extension on the fault. The formation in the well is 636 m thick (2,086 ft) and consists of alluvial-fan, playa, and lacustrine sedimentary facies, a lava flow, and rock- avalanche deposits. Analysis of the geophysical logs indicates that a K-Ar date of 23.4 Ma reported previously for the Pantano interval of the well was obtained on selected cuttings collected from a rock-avalanche deposit near the base of the unit and, thus, does not date the Pantano Formation. The middle Tertiary volcanic and sedimentary rocks have an aggregate thickness of 540 m (1,770 ft). We obtained a new 40Ar/ 39Ar age of 26.91+0.18 Ma on biotite sampled at a depth of 2,584-2,609 m (8,478-8,560 ft) from a 169-m-thick (554-ft) silicic tuff in this interval. The volcanic rocks probably correlate with other middle Tertiary volcanic rocks of the area, and the sedimentary rocks may correlate with the Cloudburst and Mineta Formations exposed on the flanks of the San Pedro Basin to the northeast. The Bisbee Group in the Exxon well is 602 m (1,975 f

Understanding tectonic stress and rock strength in the Nankai Trough accretionary prism, offshore SW Japan

NASA Astrophysics Data System (ADS)

Huffman, Katelyn A.

Understanding the orientation and magnitude of tectonic stress in active tectonic margins like subduction zones is important for understanding fault mechanics. In the Nankai Trough subduction zone, faults in the accretionary prism are thought to have historically slipped during or immediately following deep plate boundary earthquakes, often generating devastating tsunamis. I focus on quantifying stress at two locations of interest in the Nankai Trough accretionary prism, offshore Southwest Japan. I employ a method to constrain stress magnitude that combines observations of compressional borehole failure from logging-while-drilling resistivity-at-the-bit generated images (RAB) with estimates of rock strength and the relationship between tectonic stress and stress at the wall of a borehole. I use the method to constrain stress at Ocean Drilling Program (ODP) Site 808 and Integrated Ocean Drilling Program (IODP) Site C0002. At Site 808, I consider a range of parameters (assumed rock strength, friction coefficient, breakout width, and fluid pressure) in the method to constrain stress to explore uncertainty in stress magnitudes and discuss stress results in terms of the seismic cycle. I find a combination of increased fluid pressure and decreased friction along the frontal thrust or other weak faults could produce thrust-style failure, without the entire prism being at critical state failure, as other kinematic models of accretionary prism behavior during earthquakes imply. Rock strength is typically inferred using a failure criterion and unconfined compressive strength from empirical relations with P-wave velocity. I minimize uncertainty in rock strength by measuring rock strength in triaxial tests on Nankai core. I find strength of Nankai core is significantly less than empirical relations predict. I create a new empirical fit to our experiments and explore implications of this on stress magnitude estimates. I find using the new empirical fit can decrease stress predicted in the method by as much as 4 MPa at Site C0002. I constrain stress at Site C0002 using geophysical logging data from two adjacent boreholes drilled into the same sedimentary sequence with different drilling conditions in a forward model that predicts breakout width over a range of horizontal stresses (where SHmax is constrained by the ratio of stresses that would produce active faulting and Shmin is constrained from leak-off-tests) and rock strength. I then compare predicted breakout widths to observations of breakout widths from RAB images to determine the combination of stresses in the model that best match real world observations. This is the first published method to constrain both stress and strength simultaneously. Finally, I explore uncertainty in rock behavior during compressional breakout formation using a finite element model (FEM) that predicts Biot poroelastic changes in fluid pressure in rock adjacent to the borehole upon its excavation and explore the effect this has on rock failure. I test a range of permeability and rock stiffness. I find that when rock stiffness and permeability are in the range of what exists at Nankai, pore fluid pressure increase +/- 45° from Shmin and can lead to weakening of wall rock and a wider compressional failure zone than what would exist at equilibrium conditions. In a case example at, we find this can lead to an overestimate of tectonic stress using compressional failures of ~2 MPa in the area of the borehole where fluid pressure increases. In areas around the borehole where pore fluid decreases (+/- 45° from SHmax), the wall rock can strengthen which suppresses tensile failure. The implications of this research is that there are many potential pitfalls in the method to constrain stress using borehole breakouts in Nankai Trough mudstone, mostly due to uncertainty in parameters such as strength and underlying assumptions regarding constitutive rock behavior. More laboratory measurement and/or models of rock properties and rock constitutive behavior is needed to ensure the method is accurately providing constraints on stress magnitude. (Abstract shortened by ProQuest.).

Geology and geochemistry of samples from Los Alamos National Laboratory HDR Well EE-2, Fenton Hill, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laney, R.; Laughlin, A.W.; Aldrich, M.J. Jr.

1981-07-01

Petrologic, geochemical, and structural analyses of cores and cuttings obtained from 3000 to 4389-m true vertical depth in drill hole EE-2 indicate that this deeper part of the Precambrian section at Fenton Hill, New Mexico is composed primarily of a very heterogeneous and structurally anisotropic metamorphic complex, locally intruded by dikes and sills of granodioritic and monzogranitic composition. In this borehole none of these igneous bodies approach in size the 335-m-thick biotite-granodiorite body encountered at 2591-m depth beneath Fenton Hill in the other two drill holes. Contacts between the igneous and metamorphic rocks range from sharp and discordant to gradational.more » Analysis of cuttings indicates that clay-rich alteration zones are relatively common in the openhole portion of EE-2. These zones average about 20 m in thickness. Fracture sets in the Precambrian basement rock intersected by the EE-2 well bore mostly trend northeast and are steeply dipping to vertical; however, one of the sets dips gently to the northwest. Slickensided fault planes are present in a core (No.5) taken from a true vertical depth of 4195 m. Available core orientation data and geologic inference suggest that the faults dip steeply and trend between N.42/sup 0/ and 59/sup 0/E.« less

Prospect evaluation of shallow I-35 reservoir of NE Malay Basin offshore, Terengganu, Malaysia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janjua, Osama Akhtar, E-mail: janjua945@hotmail.com; Wahid, Ali, E-mail: ali.wahid@live.com; Salim, Ahmed Mohamed Ahmed, E-mail: mohamed.salim@petronas.com.my

2016-02-01

A potential accumulation of hydrocarbon that describes significant and conceivable drilling target is related to prospect. Possibility of success estimation, assuming discovery of hydrocarbons and the potential recoverable quantities range under a commercial development program are the basis of Prospect evaluation activities. The objective was to find the new shallow prospects in reservoir sandstone of I –Formation in Malay basin. The prospects in the study area are mostly consisting of faulted structures and stratigraphic channels. The methodology follows seismic interpretation and mapping, attribute analysis, evaluation of nearby well data i.e., based on well – log correlation. The petrophysical parameters analoguemore » to nearby wells was used as an input parameter for volumetric assessment. Based on analysis of presence and effectiveness, the prospect has a complete petroleum system. Two wells have been proposed to be drilled near the major fault and stratigraphic channel in I-35 reservoir that is O-1 and O-2 prospects respectively. The probability of geological success of prospect O-1 is at 35% while for O-2 is 24%. Finally, for hydrocarbon in place volumes were calculated which concluded the best estimate volume for oil in O-1 prospect is 4.99 MMSTB and O-2 prospect is 28.70 MMSTB while for gas is 29.27 BSCF and 25.59 BSCF respectively.« less

Magnetic properties of sediments from Ocean Drilling Program sites 1109, 1115, and 1118 (Leg 180), Woodlark Basin (Papua New Guinea)

NASA Astrophysics Data System (ADS)

Ishikawa, N.; Frost, G. M.

2002-09-01

Latest Miocene-Pleistocene synrift sediments at Ocean Drilling Program sites 1109, 1115, and 1118 (Leg 180), located on the hanging wall margin north of the Moresby fault in the Woodlark Basin, showed variations in magnetic parameters carried by magnetite and maghemite related to sedimentation process in the basin. At sites 1109 and 1115, an increase in the sedimentation rate at 3.8 Ma was accompanied by the deposition of sediments with low ferrimagnetic mineral concentrations. An increase in the ferrimagnetic mineral concentrations occurred between 3.4 Ma and 3.2 Ma at the three sites. The onset age of the change became younger with distance from the subsidence center of the basin near the Moresby fault: 3.4 Ma at Site 1118, 3.3 Ma at Site 1109, and 3.2 Ma at Site 1115, which implies a northward onlapping of sediments with high ferrimagnetic mineral concentration. Sediments with finer-grained ferrimagnetic minerals were deposited between 2.3 and 2.0 Ma at sites 1118 and 1109 and later, 2.8 Ma at Site 1115 during a period of a low sedimentation rate. The upper parts of sites 1109 and 1115 had a diamagnetic contribution, which is attributed to relatively high concentrations of diamagnetic pelagic materials at a low sedimentation rate associated with the low frequency of turbidites.

Imaging The Shallow Velocity Structure Of The Hikurangi Megathrust Using Full-Waveform Inversion

NASA Astrophysics Data System (ADS)

Gray, M.; Bell, R. E.; Morgan, J. V.

2017-12-01

The Hikurangi margin, offshore North Island, New Zealand, exhibits a number of different slip behaviours, including shallow slow slip events (SSEs) (<2km to 15 km). There is also a strong contrast in geodetic coupling along the margin. While reflection data provides an image of the structure, no information about physical properties is provided. Full-waveform inversion (FWI) is an imaging technique which incorporates the full seismic wavelet rather than just the first arrivals, as in traditional tomography. By propagating synthetic seismic waves through a velocity model and comparing the synthetic wavelets to the field data, we update the velocity model until the real and synthetic wavelets match. In this way, we can resolve high-resolution physical property variations which influence the seismic wavefield. In our study, FWI was used to resolve the P-wave velocity structure at the Hikurangi megathrust up to 2km. This method enables investigation of how upper-plate structure may influence plate boundary slip behaviour. In 2005, a seismic survey was carried out over the Hikurangi megathrust. The data was acquired from a 12km streamer, allowing FWI analysis up to 2km below the seabed. The results show low velocity zones correlating to faults interpreted from reflection seismic imaging. We believe these low velocity zones, particularly near the frontal thrust resolve faulting in the area, and present these faults as possible fluid conduits. As the dataset was not collected specifically for FWI, the results show promise in resolving more information at depth. As such, both a 3D seismic survey and two drilling expeditions have been approved for the period November 2017 - May 2018. The seismic survey will be carried out with parameters optimal for FWI, allow imaging of the fault boundary, which is not possible with the current 2D data. The cores will provide direct geological evidence which can be used in conjunction with velocity models to discern lithology and structure. The current result identifies the existence of overpressure and aids in drilling safety when collecting these cores. In conjunction with the new IODP cores, the FWI model will improve understanding of properties of the shallow structure of the megathrust.

PRELIMINARY DRILLING IN THE POWDER RIVER BASIN, CONVERSE, CAMPBELL, AND JOHNSON COUNTRIES, WYOMING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geslin, H.E.; Bromley, C.P.

1957-06-01

On July 16, 1953, a diamond core-drilling program was begun in the pumpkin Buttes area to secure geologic information. Drilling was terminated March 11, 1964, after 12 holes had been completed for a total of 5,813 feet. An investigational rotary noncore-drilling project was conducted from June l4, to September 17, 1954, in the southern part of the Powder River Basin, Campbell, Johnson, and Converse Counties, Wyoming. Drilling was done in the Pumpkin Buttes area and the Converse County area. A total of 52,267 feet was drilled and the average depth of hole was 75.3 feet. Forty-one anomalous areas in themore » Powder River Basin were drilled; of these, three in Converse County were found to contain possible commercial ore bodies. All of the drilling was done in the Wasatch formation of Eocene age except one locality, which was in the Fort Union formation of Paleocene age. (auth)« less

Improvement for determining the axial capacity of drilled shafts in shale in Illinois.

DOT National Transportation Integrated Search

2013-05-01

In this project, Illinois-specific design procedures were developed for drilled shafts founded in weak shale. In addition, : recommendations for field and laboratory testing to characterize the in situ condition of weak shales in Illinois were : deve...

Comparison of conventional and self-consolidating concrete for drilled shaft construction : [tech summary].

DOT National Transportation Integrated Search

2015-04-01

Significant anomalies have been observed in many of the recent drilled shaft construction projects throughout Louisiana. : The anomalies typically occur in the form of honeycombing within the zones of heavy reinforcement or sometimes at the : shaft b...

Drilled Shaft Foundations for Noise Barrier Walls and Slope Stabilization : Executive Summary

DOT National Transportation Integrated Search

2002-12-01

This research project is focused on two primary objectives. The first objective relates to the development of a methodology for using the SPT (Standard Penetration Test) results to design the laterally loaded drilled shafts. The second objective aims...

Towards a distributed infrastructure for research drilling in Europe

NASA Astrophysics Data System (ADS)

Mevel, C.; Gatliff, R.; Ludden, J.; Camoin, G.; Horsfield, B.; Kopf, A.

2012-04-01

The EC-funded project "Deep Sea and Sub-Seafloor Frontier" (DS3F) aims at developing seafloor and sub seafloor sampling strategies for enhanced understanding of deep-sea and sub seafloor processes by connecting marine research in life and geosciences, climate and environmental change, with socio-economic issues and policy building. DS3F has identified access to sub seafloor sampling and instrumentation as a key element of this approach. There is a strong expertise in Europe concerning direct access to the sub seafloor. Within the international program IODP (Integrated Ocean Drilling Program), ECORD (European Consortium for Ocean Research Drilling) has successfully developed the concept of mission specific platforms (MSPs), contracted on a project basis to drill in ice covered and shallow water areas. The ECORD Science Operator, lead by the British Geological Survey (BGS) has build a internationally recognized expertise in scientific ocean drilling, from coring in challenging environment, through down hole measurements and laboratory analysis to core curation and data management. MARUM, at the Bremen University in Germany, is one of the three IODP core repositories. Europe is also at the forefront of scientific seabed drills, with the MeBo developed by MARUM as well as the BGS seabed rocks drills. Europe also plays a important role in continental scientific drilling and the European component of ICDP (International Continental Scientific Drilling Program) is strengthening, with the recent addition of France and foreseen addition of UK. Oceanic and continental drilling have very similar scientific objectives. Moreover, they share not only common technologies, but also common data handling systems. To develop an integrated approach to technology development and usage, a move towards a a distributed infrastructure for research drilling in Europe has been initiated by these different groups. Built on existing research & operational groups across Europe, it will facilitate the sharing of technological and scientific expertise for the benefit of the science community. It will link with other relevant infrastructure initiatives such as EMSO (European Marine Seafloor Observatories). It will raise the profile of scientific drilling in Europe and hopefully lead to better funding opportunities.

Unravelling the Paleoenvironmental and Diagenetic History of Fluviolacustrine Sediments from a Northern Kenya Rift Basin Through Analysis of HSPDP West Turkana-Kaitio Core Material

NASA Astrophysics Data System (ADS)

Rabideaux, N. M.; Chaudhary, M. S.; Deocampo, D.; Feibel, C. S.; Cohen, A. S.

2016-12-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP) collected sediment cores from six rift basins in Ethiopia and Kenya. The goal of HSPDP is to construct high-resolution records of environmental change, and to understand how those changes relate to early human evolution and cultural adaptations. The West Turkana-Kaitio (WTK) site was targeted due to the abundant archeological and paleontological artifacts and fossils discovered around the basin. We conducted XRD and XRF analyses on HSPDP-WTK core material to construct a high-resolution record of paleoenvironmental conditions in the Kenya Rift during the Early Pleistocene ( 1.9-1.35 Ma). Mineralogical and geochemical trends were also used to identify the diagenetic history of fluviolacustrine sediments in the basin. The bulk mineralogy is comprised of mostly detrital feldspars, muscovite, α-quartz, and carbonates. Zeolites are present in intervals throughout the core, possibly suggesting pulses of increased salinity. Oxides and S-bearing minerals are abundant from 100-170 mbs, which may be indicative of redox and or hydrothermal processes in that interval. The lowermost portion of the core contains α- and β-quartz, pyrite and zeolites, suggesting either low-oxygen saline conditions or hydrothermal activity. Oriented clay analysis indicated multiple intervals of diagenesis, with the illitization of smectite related to hydrothermal and or microbial activity. Clay analysis provided evidence for a low degree of illitization in the upper portion of the core, whereas mixed-layered illite-smectite (I/S) contained 30-50% illite proximal to fault breccia and up to 70% illite below the faulted section, indicative of significant alteration in the lowermost portion of the core. Coupled mineralogical and geochemical analysis revealed a complex alteration history in the basin indicated by: 1) the presence of mixed-layer I/S throughout the 216 m core; 2) pronounced alteration proximal to faulting; and 3) authigenic silicates and pyrite in the basal section of the core.

Age and isotopic systematics of Cretaceous borehole and surface samples from the greater Los Angeles Basin region: Implications for the types of crust that might underlie Los Angeles and their distribution along late Cenozoic fault systems

USGS Publications Warehouse

Premo, Wayne R.; Morton, Douglas M.; Kistler, Ronald W.

2014-01-01

Nine U-Pb zircon ages were determined on plutonic rocks sampled from surface outcrops and rock chips of drill core from boreholes within the greater Los Angeles Basin region. In addition, lead-strontium-neodymium (Pb-Sr-Nd) whole-rock isotopic data were obtained for eight of these samples. These results help to characterize the crystalline basement rocks hidden in the subsurface and provide information that bears on the tectonic history of the myriad of fault systems that have dissected the Los Angeles region over the past 15 m.y. Seven of the nine samples have U-Pb ages ranging from 115 to 103 Ma and whole-rock Pb-Sr-Nd isotopic characteristics that indicate the crystalline basement underneath the greater Los Angeles Basin region is mostly part of the Peninsular Ranges batholith. Furthermore, these data are interpreted as evidence for (1) the juxtaposition of mid-Cretaceous, northern Peninsular Ranges batholith plutonic rocks against Late Cretaceous plutonic rocks of the Transverse Ranges in the San Fernando Valley, probably along the Verdugo fault; (2) the juxtaposition of older northwestern Peninsular Ranges batholith rocks against younger northeastern Peninsular Ranges batholith rocks in the northern Puente Hills, implying transposition of northeastern Peninsular Ranges batholith rocks to the west along unrecognized faults beneath the Chino Basin; and (3) juxtaposition of northern Peninsular Ranges batholith plutonic rocks against Late Cretaceous plutonic rocks of the Transverse Ranges along the San Jose fault in the northern San Jose Hills at Ganesha Park. These mainly left-lateral strike-slip faults of the eastern part of the greater Los Angeles Basin region could be the result of block rotation within the adjacent orthogonal, right-lateral, Elsinore-Whittier fault zone to the west and the subparallel San Jacinto fault zone to the east. The San Andreas fault system is the larger, subparallel, driving force further to the east.

Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

NASA Astrophysics Data System (ADS)

Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.

2014-12-01

The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

Splay fault slip in a subduction margin, a new model of evolution

NASA Astrophysics Data System (ADS)

Conin, Marianne; Henry, Pierre; Godard, Vincent; Bourlange, Sylvain

2012-08-01

In subduction zones, major thrusts called splay faults are thought to slip coseismically during large earthquakes affecting the main plate interface. We propose an analytical condition for the activation of a splay fault based on force balance calculations and suggest thrusting along the splay fault is generally conditioned by the growth of the accretionary wedge, or by the erosion of the hanging wall. In theory, normal slip on the splay fault may occur when the décollement has a very low friction coefficient seaward. Such a low friction also implies an unstable extensional state within the outer wedge. Finite element elasto-plastic calculations with a geometry based on the Nankai Kumano section were performed and confirm that this analytical condition is a valid approximation. Furthermore, localized extension at a shallow level in the splay hanging wall is observed in models for a wide range of friction coefficients (from ∼0 to the value of internal friction coefficient of the rock, here equals to 0.4). The timing of slip established for the splay fault branch drilled on Nankai Kumano transect suggests a phase of concurrent splay and accretionary wedge growth ≈2 Ma to ≈1.5 Ma, followed by a locking of the splay ≈1.3 Ma. Active extension is observed in the hanging wall. This evolution can be explained by the activation of a deeper and weaker décollement, followed by an interruption of accretion. Activation of a splay as a normal fault, as hypothesized in the case of the Tohoku 2011 earthquake, can be achieved only if the friction coefficient on the décollement drops to near zero. We conclude that the tectonic stress state largely determines long-term variations of tightly related splay fault and outer décollement activity and thus influences where and how coseismic rupture ends, but that occurrence of normal slip on a splay fault requires coseismic friction reduction.

WEXFORD containment data report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stubbs, T.; Heinle, R.

The WEXFORD event was detonated in hole U2cr of the Nevada Test Site. A plan view map of the local region of hole U2cr showing the surface projections of the faults and the local drill holes is given. The device had a depth-of-burial of 314 m in the Tunnel Beds tuff of Area 2, about 120 m above the standing water level (SWL). Stemming of the 2.44 m diameter emplacement hole followed the plan. A log of the stemming operations was maintained by Holmes and Narver. Detonation time was 07:45 PDT on August 30, 1984 and about 26 minutes latermore » the chimney collapsed to the surface leaving a small, off-center crater which grew, over several days, until it took on a cookie cutter form encompassing the emplacement hole and having a mean diameter of about 35 m. An interior, highly asymmetric crater had a mean diameter of about 12 m. No functioning monitors detected radiation arrivals in the emplacement hole above a depth of 130 m and the WEXFORD containment was considered successful.« less

Pre-cementation of deep shaft

NASA Astrophysics Data System (ADS)

Heinz, W. F.

1988-12-01

Pre-cementation or pre-grouting of deep shafts in South Africa is an established technique to improve safety and reduce water ingress during shaft sinking. The recent completion of several pre-cementation projects for shafts deeper than 1000m has once again highlighted the effectiveness of pre-grouting of shafts utilizing deep slimline boreholes and incorporating wireline technique for drilling and conventional deep borehole grouting techniques for pre-cementation. Pre-cementation of deep shaft will: (i) Increase the safety of shaft sinking operation (ii) Minimize water and gas inflow during shaft sinking (iii) Minimize the time lost due to additional grouting operations during sinking of the shaft and hence minimize costly delays and standing time of shaft sinking crews and equipment. (iv) Provide detailed information of the geology of the proposed shaft site. Informations on anomalies, dykes, faults as well as reef (gold bearing conglomerates) intersections can be obtained from the evaluation of cores of the pre-cementation boreholes. (v) Provide improved rock strength for excavations in the immediate vicinity of the shaft area. The paper describes pre-cementation techniques recently applied successfully from surface and some conclusions drawn for further considerations.

Fractures, stress and fluid flow prior to stimulation of well 27-15, Desert Peak, Nevada, EGS project

USGS Publications Warehouse

Davatzes, Nicholas C.; Hickman, Stephen H.

2009-01-01

A suite of geophysical logs has been acquired for structural, fluid flow and stress analysis of well 27-15 in the Desert Peak Geothermal Field, Nevada, in preparation for stimulation and development of an Enhanced Geothermal System (EGS). Advanced Logic Technologies Borehole Televiewer (BHTV) and Schlumberger Formation MicroScanner (FMS) image logs reveal extensive drilling-induced tensile fractures, showing that the current minimum compressive horizontal stress, Shmin, in the vicinity of well 27-15 is oriented along an azimuth of 114±17°. This orientation is consistent with the dip direction of recently active normal faults mapped at the surface and with extensive sets of fractures and some formation boundaries seen in the BHTV and FMS logs. Temperature and spinner flowmeter surveys reveal several minor flowing fractures that are well oriented for normal slip, although over-all permeability in the well is quite low. These results indicate that well 27-15 is a viable candidate for EGS stimulation and complements research by other investigators including cuttings analysis, a reflection seismic survey, pressure transient and tracer testing, and micro-seismic monitoring.

Geological Setting of Diamond Drilling for the Archean Biosphere Drilling Project, Pilbara Craton, Western Australia

NASA Astrophysics Data System (ADS)

Hickman, A.

2004-12-01

The Archean Biosphere Drilling Project (ABDP) is a collaborative international research project conducting systematic (bio)geochemical investigations to improve our understanding of the biosphere of the early Earth. The Pilbara Craton of Western Australia, which includes exceptionally well preserved 3.52 to 2.70 Ga sedimentary sequences, was selected for an innovative sampling program commencing in 2003. To avoid near-surface alteration and contamination effects, sampling was by diamond drilling to depths of between 150 and 300 m, and was located at sites where the target lithologies were least deformed and had lowest metamorphic grade (below 300°C). The first of five successful drilling sites (Jasper Deposit) targeted red, white and black chert in the 3.46 Ga Marble Bar Chert Member. This chert marks the top of a thick mafic-felsic volcanic cycle, the third of four such cycles formed by mantle plumes between 3.52 and 3.43 Ga. The geological setting was a volcanic plateau founded on 3.72 to 3.60 Ga sialic crust (isotopic evidence). The second hole (Salgash) was sited on the basal section of the fourth cycle, and sampled sulfidic (Cu-Zn-Fe), carbon-rich shale and sandstone units separated by flows of peridotite. The third hole (Eastern Creek) was sited on the margin of a moderately deep-water rift basin, the 2.95 to 2.91 Ga Mosquito Creek Basin. This is dominated by turbidites, but the sandstones and carbon-rich shales intersected at the drilling site were deposited in shallower water. The fourth and fifth holes, located 300 km apart, sampled 2.77 to 2.76 Ga continental formations of the Fortescue Group; both holes included black shales.