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Sample records for 3d seismic investigations

  1. 3-D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface

    SciTech Connect

    Levander, Alan R.

    2004-12-01

    Under ER63662, 3-D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface, we have completed a number of subprojects associated with the Hill Air Force Base (HAFB) high resolution 3-D reflection/tomography dataset.

  2. 3-D Seismic Interpretation

    NASA Astrophysics Data System (ADS)

    Moore, Gregory F.

    2009-05-01

    This volume is a brief introduction aimed at those who wish to gain a basic and relatively quick understanding of the interpretation of three-dimensional (3-D) seismic reflection data. The book is well written, clearly illustrated, and easy to follow. Enough elementary mathematics are presented for a basic understanding of seismic methods, but more complex mathematical derivations are avoided. References are listed for readers interested in more advanced explanations. After a brief introduction, the book logically begins with a succinct chapter on modern 3-D seismic data acquisition and processing. Standard 3-D acquisition methods are presented, and an appendix expands on more recent acquisition techniques, such as multiple-azimuth and wide-azimuth acquisition. Although this chapter covers the basics of standard time processing quite well, there is only a single sentence about prestack depth imaging, and anisotropic processing is not mentioned at all, even though both techniques are now becoming standard.

  3. A 3D seismic investigation of the Ray Gas Storage Reef in Macomb County, Michigan

    SciTech Connect

    Schaefer, S.F.; Dixon, R.A.

    1995-09-01

    A 4.2 square mile 3D seismic survey was acquired over the Ray Niagaran Reef Gas Storage Field in southeast Michigan as part of a program to maximize storage capacity and gas deliverability of the field. Goals of the survey were: (1) to determine if additional storage capacity could be found, either as extensions to the main reef or as undiscovered satellite reefs, (2) to determine if 3D seismic data can be utilized to quantify reservoir parameters in order to maximize the productive capacity of infill wells, and (3) to investigate the relationship between the main reef body and a low relief/flow volume gas well east of the reef. Interpretation of the 3D seismic data resulted in a detailed image of the reef, using several interpretive techniques. A seismic reflection within the reef was correlated with a known porosity zone, and the relationship between porosity and seismic amplitude was investigated. A possible connection between the main reef and the low relief gas well was identified. This project illustrates the economic value of investigating an existing storage reef with 3D seismic data, and underscores the necessity of acquiring such a survey prior to developing a new storage reservoir.

  4. A 3-D seismic investigation of the Ray gas storage reef, Macomb County, Michigan

    SciTech Connect

    Schaefer, S.F. ); Dixon, R.A. )

    1994-08-01

    A 4.2 mi[sup 2] 3-D seismic survey was acquired over the Ray Niagaran reef gas storage field in southeast Michigan as part of a program to maximize storage capacity and gas deliverability of the storage reservoir. Goals of the survey were to (1) determine if additional storage capacity could be found either as extensions to the Ray reef or as undiscovered satellite reefs, (2) investigate the relationship between the main body and a low-relief gas well east of the reef, and (3) determine if seismic data can be used to quantify reservoir parameters to maximize the productive capacity of infill wells. Interpretation of the 3-D seismic data resulted in a detailed image of the reef, using several interpretive techniques. A seismic reflection within the reef was correlated with a known porosity zone, and a possible relationship between porosity and seismic amplitude was investigated. A potential connection between the main reef and the low-relief gas well was identified. This project illustrates the economic value of investigating an existing storage reef with 3-D seismic data, and underscores the necessity of such a survey prior to developing a new storage reservoir.

  5. High-resolution 3D seismic investigation of giant seafloor craters in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Waage, Malin; Bünz, Stefan; Andreassen, Karin

    2016-04-01

    Multiple giant craters exist on the seafloor in an area of ~ 100 km2 east of Bear Island Trough in the west-central Barents Sea. It has been hypothesized that these craters might have been caused by gas eruptions following the last deglaciation. Gas seepage from the seafloor occurs abundantly in this area. The crater area is still likely to represent one of the largest hot-spots for shallow marine methane release in the arctic. In summer 2015, we acquired high-resolution P-Cable 3D seismic data in this area covering several of the craters and their associated pingo structures. Due to the shallow and hard Triassic bedrock, penetration of the seismic signals is limited to approximately 450 ms bsf. The crater structures are up to 1 km wide and 40 m deep. Pingo structures occur on the rim of some of the craters and are up to 700 m wide and up to 15 m high above the surrounding seafloor. The 3D seismic data reveals faults, fracture networks and weakness zone that resemble pipes or similar vertical, focused fluid-flow structures in the Triassic sedimentary rocks below the craters. The principal orientation of the faults is in a ~ NW-SE direction that coincides with regional faulting from Permo-Triassic extension. The seismic data also show high-amplitude anomalies beneath some of representing shallow gas accumulations that might be the intermediate source of the gas seepage. This might suggest that craters are caused by high pressured gas that migrated from deeper petroleum systems and accumulated in the shallow Triassic rocks during the last glaciation. Previous work indicate that craters of similar size are likely a cause of enormous blow-outs of gas. Our study discusses the formation mechanisms and timing of these potential blow-out craters and whether they formed during the last deglaciation, when this area was likely quite unstable as severe glacial erosion caused localized high isostatic rebound rates here. We also investigate the role of gas hydrates that might

  6. 3D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface

    SciTech Connect

    Levander, Alan Richard; Zelt, Colin A.

    2015-03-17

    The work plan for this project was to develop and apply advanced seismic reflection and wide-angle processing and inversion techniques to high resolution seismic data for the shallow subsurface to seismically characterize the shallow subsurface at hazardous waste sites as an aid to containment and cleanup activities. We proposed to continue work on seismic data that we had already acquired under a previous DoE grant, as well as to acquire additional new datasets for analysis. The project successfully developed and/or implemented the use of 3D reflection seismology algorithms, waveform tomography and finite-frequency tomography using compressional and shear waves for high resolution characterization of the shallow subsurface at two waste sites. These two sites have markedly different near-surface structures, groundwater flow patterns, and hazardous waste problems. This is documented in the list of refereed documents, conference proceedings, and Rice graduate theses, listed below.

  7. Investigation of 3-D lateral variations on seismic waveform modeling, in preparation for the InSight mission to Mars

    NASA Astrophysics Data System (ADS)

    Drilleau, M.; Dubois, A.; Blanchette-Guertin, J. F.; Kawamura, T.; Lognonne, P. H.

    2015-12-01

    In 2016, the InSight mission will provide the very first seismic records from Mars after installing a seismometer on the surface of the Red Planet. Obtaining information on the deep 1-D seismic structure of Mars using a single geophysical station will be challenging. However, successful test inversions using body and surface waves have been presented in a preliminary study by Panning et al. (2015). Future investigations need now to focus on inversions making a complete use of the seismic waveform. An important challenge is to investigate the effects of 3-D lateral variations of seismic velocity structures on seismograms. The HOPT (Higher Order Perturbation Theory) code originally developed by P. Lognonné and E. Clévédé (Lognonné, 1991 ; Lognonné and Clévédé, 2002) and based on the perturbation theory allows for the computation of synthetic seismograms in a 3-D Earth. We adapted the code for Mars and computed surface wave synthetics in a 3-D planet, initially only considering the effects of the planet's ellipticity as well as the lateral variations in the depth of the Moho which are known through gravity measurements (e.g. Neumann et al., 2004). Additional constraints from lateral variations in topography will be the focus of future work. These synthetics can be compared to future seismic data in order to identify a suite of Martian internal structure models that best match the data. To do so, we first need to estimate the resolvable parameters concerning the Mars deep interior while considering the 3-D effects, which is the main goal of this study. Furthermore, in preparation for the InSight mission data return phase, the computation of these synthetic (but realistic) seismograms is primordial to test the softwares developed by the InSight Mars Quake and Mars Structure Services (in charge of locating the seismic events, and using them to assess the internal structure of Mars).

  8. Investigation into 3D earth structure and sources using full seismic waveforms

    NASA Astrophysics Data System (ADS)

    Covellone, Brian M.

    Seismograms are the result of the complex interactions between a seismic source, a propagation medium and the seismograph's response. Through the use of 3-dimensional modeling and full seismic waveform data, we quantify and minimize errors associated with the source and propagation medium within our data sets. We compile a new and unique earthquake catalog for the Middle East that is openly available to the public. We quantify the benefits of using a 3-dimensional model relative to a 1-dimensional model to minimizing error in earthquake moment tensors and identify where in the waveform 3-dimensional models outperform 1-dimensional models. Two new and unique 3-dimensional seismic wave speed models are computed for the Ontong Java plateau and eastern North American margin.Both models are significant improvements to the resolution of wave speed structures in the crust and upper mantle and provide new information for the evaluation of tectonic features.

  9. Pore Space Geometry and Seismic Anisotropy of Rocks: 3-D Experimental Investigation

    NASA Astrophysics Data System (ADS)

    Spacek, P.; Melichar, R.; Ulrich, S.

    2004-12-01

    Pressure-driven closing of the pores in the rock sample results in changes of its effective physical properties. We use 3-D ultrasonic pulse-transmission method to characterize the relationships between the spatial distribution of microcracks and elastic anisotropy of the rock. With the use of apparatus developed in Geophysical Institute, Prague, the P-wave velocities and amplitudes ({\\IT VP} and {\\IT AP}) are measured in 132 directions on spherical rock samples. The measurements are carried out at several steps of confining pressure within pressure-increasing and pressure-decreasing paths (0.1-400, 400-0.1 MPa). Then the directions of maximum and minimum velocities and amplitudes are found for which the measurements is repeated under continually changing pressure. As the measurements are repeated at the same position under various pressures, the data can be processed so that the change of the {\\IT VP} and {\\IT AP} between the individual pressure-steps and the hysteresis at particular pressure can be seen directly. The resulting differential diagrams show the magnitude of {\\IT VP} and {\\IT AP} changes in 3-D which are mainly due to the pressure-induced closing of microcracks, and respectively, the flexibility of the microcracks. Using the data measured at high confining pressure or those computed with averaging method we are able to distinguish the influence the deformation-induced lattice re-orientations from the pore-related properties. Numerous measurements carried out on various rock samples show that the anisotropic patterns of {\\IT VP} and {\\IT AP} changes due to the closing of oriented microcracks and other pores highly correlate with the macroscopic structural features of the rock (preferred grain-shape orientation, fracture cleavage, stretching lineation) and are sensitive to them. It is believed that in such cases where the structural features associated with porosity can not be observed directly, the above outlined method will be applicable as a

  10. Characterization of the 3-D fracture setting of an unstable rock mass: From surface and seismic investigations to numerical modeling

    NASA Astrophysics Data System (ADS)

    Colombero, C.; Baillet, L.; Comina, C.; Jongmans, D.; Vinciguerra, S.

    2017-08-01

    The characterization of the fracturing state of a potentially unstable rock cliff is a crucial requirement for stability assessments and mitigation purposes. Classical measurements of fracture location and orientation can however be limited by inaccessible rock exposures. The steep topography and high-rise morphology of these cliffs, together with the widespread presence of fractures, can additionally condition the success of geophysical prospecting on these sites. In order to mitigate these limitations, an innovative approach combining noncontact geomechanical measurements, active and passive seismic surveys, and 3-D numerical modeling is proposed in this work to characterize the 3-D fracture setting of an unstable rock mass, located in NW Italian Alps (Madonna del Sasso, VB). The 3-D fracture geometry was achieved through a combination of field observations and noncontact geomechanical measurements on oriented pictures of the cliff, resulting from a previous laser-scanning and photogrammetric survey. The estimation of fracture persistence within the rock mass was obtained from surface active seismic surveys. Ambient seismic noise and earthquakes recordings were used to assess the fracture control on the site response. Processing of both data sets highlighted the resonance properties of the unstable rock volume decoupling from the stable massif. A finite element 3-D model of the site, including all the retrieved fracture information, enabled both validation and interpretation of the field measurements. The integration of these different methodologies, applied for the first time to a complex 3-D prone-to-fall mass, provided consistent information on the internal fracturing conditions, supplying key parameters for future monitoring purposes and mitigation strategies.

  11. Investigating Deep-Marine Sediment Waves in the Northern Gulf of Mexico Using 3D Seismic Data

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Gani, M. R.

    2016-12-01

    Deep-water depositional elements have been studied for decades using outcrop, flume tank, sidescan sonar, and seismic data. Even though they have been well recognized by researchers, the improvements in the quality of 3D seismic data with increasingly larger dimension allow detailed analysis of deep-water depositional elements with new insights. This study focuses on the deep-marine sediment waves in the northern Gulf of Mexico. By interpreting a 3D seismic dataset covering 635 km2 at Mississippi Canyon and Viosca Knoll areas, large sediment waves, generated by sediment gravity flows, were mapped and analyzed with various seismic attributes. A succession of sediment waves, approximately 100 m in thickness, is observed on the marine slope that tapers out at the toe of the slope. The individual sediment wave exhibits up to 500 m in wavelength and up to 20 m in height. The wave crests oriented northeast-southwest are broadly aligned parallel to the regional slope-strike, indicating their sediment gravity flow origin. The crestlines are straight or slightly sinuous, with sinuosity increasing downslope. Their anti-dune patterns likely imply the presence of supercritical flows. The sediment waves have a retrogradational stacking pattern. Seismic amplitude maps of each sediment wave revealed that after depositing the majority of sheet-like sands on the upper slope, sediment gravity flows started to form large sediment waves on the lower slope. The steep and narrow upcurrent flanks of the sediment waves always display higher amplitudes than the gentle and wide downcurrent flanks, indicating that the sands were likely preferentially trapped along the upcurrent flanks, whereas the muds spread along the downcurrent flanks. The formation of sediment waves likely requires a moderate sand-mud ratio, as suggested by these observations: (1) absence of sediment waves on the upper slope where the sands were mainly deposited as unconfined sheets with a high sand-mud ratio; (2

  12. 3-D seismic data for geohazards assessment

    SciTech Connect

    Gafford, W.T.

    1996-10-01

    Three-dimensional (3-D) seismic data, acquired for oil and gas exploration purposes, is now being used to supplement, or in some cases, even replace conventional high resolution geohazard surveys in the Gulf of Mexico. The use of 3-D seismic data has improved the identification and understanding of some types of geohazards and has resulted in a more thorough interpretation of the shallow geologic section. The use of seismic interpretation workstations has allowed the geohazard interpreter to apply new tools in geohazard analysis. Some of the newer geohazard analysis. Some of the newer geophysical technologies used for exploration purposes are now being adapted for use in the identification and assessment of drilling hazards in the near-seafloor sedimentary section.

  13. Application of 3D reflection seismic methods to mineral exploration

    NASA Astrophysics Data System (ADS)

    Urosevic, Milovan

    2013-04-01

    Seismic exploration for mineral deposits is often tested by excessively complex structures, regolith heterogeneity, intrinsically low signal to noise ratio, ground relief and accessibility. In brown fields, where the majority of the seismic surveys have been conducted, existing infrastructure, old pits and tailings, heavy machinery in operation, mine drainage and other mine related activities are further challenging the application of seismic methods and furthermore increasing its cost. It is therefore not surprising that the mining industry has been reluctant to use seismic methods, particularly 3D for mineral exploration, primarily due to the high cost, but also because of variable performance, and in some cases ambiguous interpretation results. However, shallow mineral reserves are becoming depleted and exploration is moving towards deeper targets. Seismic methods will be more important for deeper investigations and may become the primary exploration tool in the near future. The big issue is if we have an appropriate seismic "strategy" for exploration of deep, complex mineral reserves. From the existing case histories worldwide we know that massive ore deposits (VMS, VHMS) constitute the best case scenario for the application of 3D seismic. Direct targeting of massive ore bodies from seismic has been documented in several case histories. Sediment hosted deposits could, in some cases, can also produce a detectable seismic signature. Other deposit types such as IOCG and skarn are much more challenging for the application of seismic methods. The complexity of these deposits requires new thinking. Several 3D surveys acquired over different deposit types will be presented and discussed.

  14. 3D seismic image processing for interpretation

    NASA Astrophysics Data System (ADS)

    Wu, Xinming

    Extracting fault, unconformity, and horizon surfaces from a seismic image is useful for interpretation of geologic structures and stratigraphic features. Although interpretation of these surfaces has been automated to some extent by others, significant manual effort is still required for extracting each type of these geologic surfaces. I propose methods to automatically extract all the fault, unconformity, and horizon surfaces from a 3D seismic image. To a large degree, these methods just involve image processing or array processing which is achieved by efficiently solving partial differential equations. For fault interpretation, I propose a linked data structure, which is simpler than triangle or quad meshes, to represent a fault surface. In this simple data structure, each sample of a fault corresponds to exactly one image sample. Using this linked data structure, I extract complete and intersecting fault surfaces without holes from 3D seismic images. I use the same structure in subsequent processing to estimate fault slip vectors. I further propose two methods, using precomputed fault surfaces and slips, to undo faulting in seismic images by simultaneously moving fault blocks and faults themselves. For unconformity interpretation, I first propose a new method to compute a unconformity likelihood image that highlights both the termination areas and the corresponding parallel unconformities and correlative conformities. I then extract unconformity surfaces from the likelihood image and use these surfaces as constraints to more accurately estimate seismic normal vectors that are discontinuous near the unconformities. Finally, I use the estimated normal vectors and use the unconformities as constraints to compute a flattened image, in which seismic reflectors are all flat and vertical gaps correspond to the unconformities. Horizon extraction is straightforward after computing a map of image flattening; we can first extract horizontal slices in the flattened space

  15. 3D seismic imaging, example of 3D area in the middle of Banat

    NASA Astrophysics Data System (ADS)

    Antic, S.

    2009-04-01

    3D seismic imaging was carried out in the 3D seismic volume situated in the middle of Banat region in Serbia. The 3D area is about 300 km square. The aim of 3D investigation was defining geology structures and techtonics especially in Mesozoik complex. The investigation objects are located in depth from 2000 to 3000 m. There are number of wells in this area but they are not enough deep to help in the interpretation. It was necessary to get better seismic image in deeper area. Acquisition parameters were satisfactory (good quality of input parameters, length of input data was 5 s, fold was up to 4000 %) and preprocessed data was satisfied. GeoDepth is an integrated system for 3D velocity model building and for 3D seismic imaging. Input data for 3D seismic imaging consist of preprocessing data sorted to CMP gathers and RMS stacking velocity functions. Other type of input data are geological information derived from well data, time migrated images and time migrated maps. Workflow for this job was: loading and quality control the input data (CMP gathers and velocity), creating initial RMS Velocity Volume, PSTM, updating the RMS Velocity Volume, PSTM, building the Initial Interval Velocity Model, PSDM, updating the Interval Velocity Model, PSDM. In the first stage the attempt is to derive initial velocity model as simple as possible as.The higher frequency velocity changes are obtained in the updating stage. The next step, after running PSTM, is the time to depth conversion. After the model is built, we generate a 3D interval velocity volume and run 3D pre-stack depth migration. The main method for updating velocities is 3D tomography. The criteria used in velocity model determination are based on the flatness of pre-stack migrated gathers or the quality of the stacked image. The standard processing ended with poststack 3D time migration. Prestack depth migration is one of the powerful tool available to the interpretator to develop an accurate velocity model and get

  16. Walker Ranch 3D seismic images

    DOE Data Explorer

    Robert J. Mellors

    2016-03-01

    Amplitude images (both vertical and depth slices) extracted from 3D seismic reflection survey over area of Walker Ranch area (adjacent to Raft River). Crossline spacing of 660 feet and inline of 165 feet using a Vibroseis source. Processing included depth migration. Micro-earthquake hypocenters on images. Stratigraphic information and nearby well tracks added to images. Images are embedded in a Microsoft Word document with additional information. Exact location and depth restricted for proprietary reasons. Data collection and processing funded by Agua Caliente. Original data remains property of Agua Caliente.

  17. A comparative study between a rectilinear 3-D seismic survey and a concentric-circle 3-D seismic survey

    SciTech Connect

    Maldonado, B.; Hussein, H.S.

    1994-12-31

    Due to the rectilinear nature of the previous 3D seismic survey, the details necessary for proper interpretation were absent. Theoretically, concentric 3D seismic technology may provide an avenue for gaining more and higher quality data coverage. Problems associated with recording a rectilinear 3D seismic grid over the salt dome in this area have created the need to investigate the use of such procedures as the concentric-circle 3D seismic acquisition technique. The difficulty of imaging salt dome flanks with conventional rectilinear 3D seismic may be a result of the inability to precisely predict the lateral velocity-field variation adjacent to both salt and sediments. The dramatic difference in the interval velocities of salt and sediments causes the returning ray to severely deviate from being a hyperbolic path. This hampers the ability to predict imaging points near the salt/sediment interface. Perhaps the most difficult areas to image with rectilinear seismic surveys are underneath salt overhangs. Modeling suggests that a significant increase in the number of rays captured from beneath a salt overhang can be achieved with the concentric-circle method. This paper demonstrates the use of the ``circle shoot`` on a survey conducted over a salt dome in the Gulf of Mexico. A total of 80 concentric circles cover an area which is equivalent to 31,000 acres. The final post-stack data were sorted into bins with dimensions of 25 meters by 25 meters. A comparison of 3D rectilinear shooting vs. 3D concentric circle shooting over the same area will show an improvement in data quality and signal-to-noise characteristics.

  18. Imaging fault zones using 3D seismic image processing techniques

    NASA Astrophysics Data System (ADS)

    Iacopini, David; Butler, Rob; Purves, Steve

    2013-04-01

    Significant advances in structural analysis of deep water structure, salt tectonic and extensional rift basin come from the descriptions of fault system geometries imaged in 3D seismic data. However, even where seismic data are excellent, in most cases the trajectory of thrust faults is highly conjectural and still significant uncertainty exists as to the patterns of deformation that develop between the main faults segments, and even of the fault architectures themselves. Moreover structural interpretations that conventionally define faults by breaks and apparent offsets of seismic reflectors are commonly conditioned by a narrow range of theoretical models of fault behavior. For example, almost all interpretations of thrust geometries on seismic data rely on theoretical "end-member" behaviors where concepts as strain localization or multilayer mechanics are simply avoided. Yet analogue outcrop studies confirm that such descriptions are commonly unsatisfactory and incomplete. In order to fill these gaps and improve the 3D visualization of deformation in the subsurface, seismic attribute methods are developed here in conjunction with conventional mapping of reflector amplitudes (Marfurt & Chopra, 2007)). These signal processing techniques recently developed and applied especially by the oil industry use variations in the amplitude and phase of the seismic wavelet. These seismic attributes improve the signal interpretation and are calculated and applied to the entire 3D seismic dataset. In this contribution we will show 3D seismic examples of fault structures from gravity-driven deep-water thrust structures and extensional basin systems to indicate how 3D seismic image processing methods can not only build better the geometrical interpretations of the faults but also begin to map both strain and damage through amplitude/phase properties of the seismic signal. This is done by quantifying and delineating the short-range anomalies on the intensity of reflector amplitudes

  19. Exploring the seismic expression of fault zones in 3D seismic volumes

    NASA Astrophysics Data System (ADS)

    Iacopini, D.; Butler, R. W. H.; Purves, S.; McArdle, N.; De Freslon, N.

    2016-08-01

    Mapping and understanding distributed deformation is a major challenge for the structural interpretation of seismic data. However, volumes of seismic signal disturbance with low signal/noise ratio are systematically observed within 3D seismic datasets around fault systems. These seismic disturbance zones (SDZ) are commonly characterized by complex perturbations of the signal and occur at the sub-seismic (10 s m) to seismic scale (100 s m). They may store important information on deformation distributed around those larger scale structures that may be readily interpreted in conventional amplitude displays of seismic data. We introduce a method to detect fault-related disturbance zones and to discriminate between this and other noise sources such as those associated with the seismic acquisition (footprint noise). Two case studies from the Taranaki basin and deep-water Niger delta are presented. These resolve SDZs using tensor and semblance attributes along with conventional seismic mapping. The tensor attribute is more efficient in tracking volumes containing structural displacements while structurally-oriented semblance coherency is commonly disturbed by small waveform variations around the fault throw. We propose a workflow to map and cross-plot seismic waveform signal properties extracted from the seismic disturbance zone as a tool to investigate the seismic signature and explore seismic facies of a SDZ.

  20. Exploring the seismic expression of fault zones in 3D seismic volumes

    NASA Astrophysics Data System (ADS)

    Iacopini, David; Butler, Rob; Purves, Steve

    2016-04-01

    Mapping and understanding distributed deformation is a major challenge for the structural interpretation of seismic data. However, volumes of seismic signal disturbance with low signal/noise ratio are systematically observed within 3D seismic datasets around fault systems. These seismic disturbance zones (SDZ) are commonly characterized by complex perturbations of the signal and occur at the sub-seismic to seismic scale. They may store important information on deformation distributed around those larger scale structures that may be readily interpreted in conventional amplitude displays of seismic data scale. We introduce a method to detect fault-related disturbance zones and to discriminate between this and other noise sources such as those associated with the seismic acquisition (footprint noise). Two case studies, from the Taranaki basin and deep-water Niger delta are presented. These resolve structure within SDZs using tensor and semblance attributes along with conventional seismic mapping. The tensor attribute is more efficient in tracking volumes containing structural displacements while structurally-oriented semblance coherency is commonly disturbed by small waveform variations around the fault throw. We propose a workflow to map and cross-plot seismic waveform signal properties extracted from the seismic disturbance zone as a tool to investigate the seismic signature and explore seismic facies of a SDZ.

  1. 3-D seismic imaging of complex geologies

    SciTech Connect

    Womble, D.E.; Dosanjh, S.S.; VanDyke, J.P.; Oldfield, R.A.; Greenberg, D.S.

    1995-02-01

    We present three codes for the Intel Paragon that address the problem of three-dimensional seismic imaging of complex geologies. The first code models acoustic wave propagation and can be used to generate data sets to calibrate and validate seismic imaging codes. This code reported the fastest timings for acoustic wave propagation codes at a recent SEG (Society of Exploration Geophysicists) meeting. The second code implements a Kirchhoff method for pre-stack depth migration. Development of this code is almost complete, and preliminary results are presented. The third code implements a wave equation approach to seismic migration and is a Paragon implementation of a code from the ARCO Seismic Benchmark Suite.

  2. 3D Seismic Reflection Experiment over the Galicia Deep Basin

    NASA Astrophysics Data System (ADS)

    Sawyer, D. S.; Jordan, B.; Reston, T. J.; Minshull, T. A.; Klaeschen, D.; Ranero, C.; Shillington, D. J.; Morgan, J. K.

    2014-12-01

    In June thru September, 2013, a 3D reflection and a long offset seismic experiment were conducted at the Galicia rifted margin by investigators from the US, UK, Germany, and Spain. The 3D multichannel experiment covered 64 km by 20 km (1280 km2), using the RV Marcus Langseth. Four streamers 6 km long were deployed at 12.5 m hydrophone channel spacing. The streamers were 200 m apart. Two airgun arrays, each 3300 cu in, were fired alternately every 37.5 m, to collectively yield a 400 m wide sail line consisting of 8 CMP lines at 50 m spacing. The long offset seismic experiment included 72 short period OBS's deployed below the 3D reflection survey box. Most of the instruments recorded all the shots from the airgun array shots. The 3D seismic box covered a variety of geologic features. The Peridotite Ridge (PR), is associated with the exhumation of upper mantle rocks to the seafloor during the final stage of the continental separation between the Galicia Bank and the Grand Banks of Newfoundland. The S reflector is present below most of the continental blocks under the deep Galicia basin. S is interpreted to be a low-angle detachment fault formed late in the rifting process, and a number of rotated fault block basins and ranges containing pre and syn-rift sediments. Initial observations from stacked 3D seismic data, and samples of 2D pre-stack time migrated (PSTM) 3D seismic data show that the PR is elevated above the present seafloor in the South and not exposed through the seafloor in the North. The relative smoothness of the PR surface for the entire 20 km N-S contrasts with the more complex, shorter wavelength, faulting of the continental crustal blocks to the east. The PR does not seem to show offsets or any apparent internal structure. The PSTM dip lines show substantial improvement for the structures in the deep sedimentary basin East of the PR. These seem to extend the S reflector somewhat farther to the West. The migrated data show a substantial network of

  3. Using submarine landforms to investigate glacial history, chronology and evolution during the Late Cenozoic: A 3D seismic case study of the mid-Norwegian shelf.

    NASA Astrophysics Data System (ADS)

    Newton, Andrew; Huuse, Mads

    2014-05-01

    The mid-Norwegian continental shelf and its succession through time has in places preserved a detailed geomorphological record of glacial and interglacial ice dynamics. Most work has concentrated on the most recent glaciations and therefore the full extent and dynamics of older glaciations is poorly understood. In this work several 3D seismic volumes, from across the mid-Norwegian shelf, are used together to image the glacial-interglacial sequences and piece together a chronology of shelf edge glaciation throughout the Late Cenozoic up until the most recent Weichselian glaciation. The 3D seismic data are supplemented with a large number of 2D seismic profiles and oil industry boreholes are used for calibration and horizon dating. The work presented here will help in the effort to establish a better detailed and more tightly constrained chronology of the extent and timings of different glaciations throughout the Late Cenozoic. Developing a better chronology is of critical importance for helping to calibrate current models of ice sheet and landscape evolution so that contemporary changes may be better understood. The basic geology of the system shows a progradation of the shelf edge towards the basin. The stratigraphical succession comprises evidence for several erosional events associated with the Elsterian, Saalian and Weichselian glaciations during the mid- to late Pleistocene. At depth the pre-glacial Neogene deposits are characterized by widespread polygonal faulting. Within the 3D seismic blocks several glaciogenic structures are visible. Most notably these include an abundance of linear and curvilinear mega-scale glacial lineations, which reach lengths of over 50 km, and iceberg scours that vary in length from 100 m to over 7 km. An array of different sized channels offer insight into the flow characteristics of pro-glacial and subglacial regimes during previous glaciations. Lateral moraines are also present in the seismic data and help to delineate past

  4. 3D Seismic Reflection Experiment Over the Galicia Deep Basin

    NASA Astrophysics Data System (ADS)

    Sawyer, Dale; Jordan, Brian; Tesi Sanjurjo, Mari; Alexanian, Ara; Morgan, Julia; Shillington, Donna; Reston, Timothy; Minshull, Timothy; Klaeschen, Dirk; Ranero, César

    2014-05-01

    In June thru September, 2013, a 3D reflection and a long offset seismic experiment were conducted at the Galicia rifted margin by investigators from the US, UK, Germany, and Spain. The 3D multichannel experiment covered 64 km by 20 km (1280 km2), using the RV Marcus Langseth. Four streamers 6 km long were deployed at 12.5 m hydrophone channel spacing. The streamers were 200 m apart. Two airgun arrays, each 3300 cu in, were fired alternately every 37.5 m, to collectively yield a 400 m wide sail line consisting of 8 CMP lines at 50 m spacing. The long offset seismic experiment included 72 short period OBS's deployed below the 3D reflection survey box. Most of the instruments recorded all the shots from the airgun array shots. The 3D seismic box covered a variety of geologic features. The Peridotite Ridge (PR), is associated with the exhumation of upper mantle rocks to the seafloor during the final stage of the continental separation between the Galicia Bank and the Grand Banks of Newfoundland. The S reflector is present below most of the continental blocks under the deep Galicia basin. S is interpreted to be a low-angle detachment fault formed late in the rifting process, and a number of rotated fault block basins and ranges containing pre and syn-rift sediments. Initial observations from stacked, but not yet migrated, 3D seismic data show that the PR is elevated above the present seafloor in the South and not exposed through the seafloor in the North. The relative smoothness of the PR surface for the entire 20 km N-S contrasts with the more complex, shorter wavelength, faulting of the continental crustal blocks to the east. The PR does not seem to show offsets or any apparent internal structure. However, migration will be required to see internal structure of the PR. Between the PR and the western most rifted continental crustal blocks, is a sedimentary basin about as wide as the PR and very different from the sedimentary basins bounded by the continental crustal

  5. Seismic modeling of Earth's 3D structure: Recent advancements

    NASA Astrophysics Data System (ADS)

    Ritsema, J.

    2008-12-01

    Global models of Earth's seismic structure continue to improve due to the growth of seismic data sets, implementation of advanced wave propagations theories, and increased computational power. In my presentation, I will summarize seismic tomography results from the past 5-10 years. I will compare the most recent P and S velocity models, discuss model resolution and model interpretation, and present an, admittedly biased, list of research directions required to develop the next generation 3D models.

  6. Investigating the complex structural integrity of the Zeit Bay Field, Gulf of Suez, Egypt, using interpretation of 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Afife, M.; Salem, M.; Aziz, M. Abdel

    2017-07-01

    Zeit Bay Field is one of the most important oil-bearing fields in the Gulf of Suez, Egypt, producing oil from the fractured basement rocks. Due to the complex structural setting of the area and the classical exploration concept that was based mainly on 2D seismic survey data, the area suffered from limited hydrocarbon interest for several years. During this time, most of the drilled wells hit structural highs and resulted in several dry holes. The present study is based on the interpretation of more recently acquired 3D seismic survey data as, matched with the available well logs, used to understand the complex structural setting of the Zeit Bay Field and provide insight into the entrapment style of the implied hydrocarbons. Several selected seismic cross sections were constructed, to extract subsurface geologic information, using available seismic profiles and wells. In addition, structure contour maps (isochronous maps, converted to depth maps) were constructed for the peaks of the basement, Nubian Sandstone, Kareem and Belayim Formations. Folds (anticlines and synclines) and faults (dip-slip) are identified on these maps, both individually and in groups, giving rise to step-like belts, as well as graben and horst blocks.

  7. Lossless compression of 3D seismic data using a horizon displacement compensated 3D lifting scheme

    NASA Astrophysics Data System (ADS)

    Meftah, Anis; Antonini, Marc; Ben Amar, Chokri

    2010-01-01

    In this paper we present a method to optimize the computation of the wavelet transform for the 3D seismic data while reducing the energy of coefficients to the minimum. This allow us to reduce the entropy of the signal and so increase the compression ratios. The proposed method exploits the geometrical information contained in the seismic 3D data to optimize the computation of the wavelet transform. Indeed, the classic filtering is replaced by a filtering following the horizons contained in the 3D seismic images. Applying this approach in two dimensions permits us to obtain wavelets coefficients with lowest energy. The experiments show that our method permits to save extra 8% of the size of the object compared to the classic wavelet transform.

  8. The 3-D seismic revolution: Impact on exploration and development

    SciTech Connect

    Nestvold, W. )

    1994-07-01

    The success of an exploration and production project hinges on a knowledge of the subsurface. An accurate seismic image of subsurface structure and lithology is a weapon in the armory against the risk of drilling an earth into which one cannot see. The tool for this is 3-D seismic, and it has no peer. The authors believe that 3-D seismic is revolutionizing the geophysical industry with far-reaching effect on the exploration and production business worldwide. This belief is corroborated by a broad spectrum of the industry. Although the details vary, the message is always the same, and always clear. Most exploration 3-D surveys to date have been acquired in known hydrocarbon fairways. These surveys not only reduce the risk of drilling an exploration or appraisal dry hole, but also add reserves by enabling new oil and gas to be found.

  9. 3D Seismic Imaging over a Potential Collapse Structure

    NASA Astrophysics Data System (ADS)

    Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

  10. Frozen Gaussian approximation for 3-D seismic wave propagation

    NASA Astrophysics Data System (ADS)

    Chai, Lihui; Tong, Ping; Yang, Xu

    2017-01-01

    We present a systematic introduction on applying frozen Gaussian approximation (FGA) to compute synthetic seismograms in 3-D earth models. In this method, seismic wavefield is decomposed into frozen (fixed-width) Gaussian functions, which propagate along ray paths. Rather than the coherent state solution to the wave equation, this method is rigorously derived by asymptotic expansion on phase plane, with analysis of its accuracy determined by the ratio of short wavelength over large domain size. Similar to other ray-based beam methods (e.g. Gaussian beam methods), one can use relatively small number of Gaussians to get accurate approximations of high-frequency wavefield. The algorithm is embarrassingly parallel, which can drastically speed up the computation with a multicore-processor computer station. We illustrate the accuracy and efficiency of the method by comparing it to the spectral element method for a 3-D seismic wave propagation in homogeneous media, where one has the analytical solution as a benchmark. As another proof of methodology, simulations of high-frequency seismic wave propagation in heterogeneous media are performed for 3-D waveguide model and smoothed Marmousi model, respectively. The second contribution of this paper is that, we incorporate the Snell's law into the FGA formulation, and asymptotically derive reflection, transmission and free surface conditions for FGA to compute high-frequency seismic wave propagation in high contrast media. We numerically test these conditions by computing traveltime kernels of different phases in the 3-D crust-over-mantle model.

  11. 3-D seismic exploration in the Ames hole

    SciTech Connect

    Ainsworth, K.R.

    1995-09-01

    The Ames Crater of Major County, Oklahoma has been one of the more controversial drilling projects to emerge in the Mid-Continent province in this decade. Within the crater, dolomitic and granodiorite breccias produce substantial quantities of oil and gas within structurally controlled accumulations. To understand the structural complexities of the crater, Continental Resources, in partnership with other Ames operators, acquired 3-D seismic data in four separate acquisition projects across various exploratory and development projects across the crater. Integrated seismic and subsurface control revealed four separate features within the principal crater floor oil and gas accumulation. Using the 3-D data as a lead tool, these companies identified and developed a significant number of commercial tests within the limits of the seismic surveys. Although the tool generally proved to be successful, reservoir variability, velocity variations, and interpretational errors resulted in some non-commercial and dry tests.

  12. How 3-D, 3-C seismic characterized a carbonate reservoir

    SciTech Connect

    Arestad, J.F.; Mattocks, B.W.; Davis, T.L.; Benson, R.D.

    1995-04-01

    The Reservoir Characterization Project (RCP) at the Colorado School of Mines has pioneered research into 3-D, 3-C (multicomponent) reflection seismology for nearly a decade utilizing both P-wave and S-wave sources. Multicomponent-seismic surveys provide significantly more information about petroleum reservoirs than compressional-wave surveys. Initial 3-D, 3-C surveys acquired by RCP were targeted at characterizing naturally fractured reservoirs. The current phase of the project is oriented towards utilizing shear waves to discriminate lithologic and diagenetic changes within stratigraphic reservoirs where compressional-seismic data has not be effective. The Joffre field, Nisku reservoir, is the site of RCP`s ongoing multidisciplinary research effort in Western Canada. The research team is directed by Colorado School of Mines faculty with graduate team members from geology, geophysics and petroleum engineering departments. While this study is still in progress, some key findings and directions of this research are reported here. The following topics will be discussed: Joffre field 3-D, 3-C survey; compressional wave 3-D technique; shear-wave 3-D technique; converted-wave 3-D technique; reservoir characterization, and future directions.

  13. 3-D vertical seismic profiling at LLNL Site 300

    SciTech Connect

    Bainer, R.; Rector, J.; Milligan, P.

    1997-01-29

    The initial goal of the 3-D Vertical Seismic Profiling (VSP) work at LLNL was to characterize seismic wave velocities and frequencies below the vadose zone to design the acquisition geometry for a 3-D shallow surface seismic reflection survey. VSPs are also used routinely to provide a link between surface seismic data and well logs. However, a test 2-D seismic line recorded at LLNL in the Spring of 1994 indicated that obtaining high quality reflection images below the vadose zone, yet shallower that 50 m, would require an expensive, very finely sampled survey ({lt} 1 m receiver spacing). Extensive image processing of the LLNL 2-D test line indicated that the only reliable reflection was from the top of the water table. Surprisingly, these results were very different than recent 3-D seismic work recorded at other sites, where high quality, high frequency surface (up to 300 Hz) reflection images were obtained as shallow as 20m. We believe that the differences are primarily due to the comparatively deep vadose zone at LLNL (15 to 30m) as compared to 0-5m at other sites. The thick vadose zone attenuates the reflection signals, particularly at the high frequencies (above 100 @). In addition, the vadose zone at LLNL creates a seismogram in which surface-propagating noise overlaps with the reflection signals for reflections above 50 m. By contrast, when the vadose zone is not thick, high frequencies can propagate and noise will not overlap with reflections as severely. Based on the results from the 2-D seismic line and the encouraging results from a VSP run concurrent with the 2-D seismic experiment, we modified the objectives of the research and expanded the scope of the VSP imaging at LLNL. We conducted two 3-D multi-offset VSP experiments at LLNL in the Summer and Fall of 1994. These VSP experiments were designed to characterize the seismic propagation characteristics at two different locations on the LLNL site: the first was a well with a relatively shallow water

  14. Advanced computational tools for 3-D seismic analysis

    SciTech Connect

    Barhen, J.; Glover, C.W.; Protopopescu, V.A.

    1996-06-01

    The global objective of this effort is to develop advanced computational tools for 3-D seismic analysis, and test the products using a model dataset developed under the joint aegis of the United States` Society of Exploration Geophysicists (SEG) and the European Association of Exploration Geophysicists (EAEG). The goal is to enhance the value to the oil industry of the SEG/EAEG modeling project, carried out with US Department of Energy (DOE) funding in FY` 93-95. The primary objective of the ORNL Center for Engineering Systems Advanced Research (CESAR) is to spearhead the computational innovations techniques that would enable a revolutionary advance in 3-D seismic analysis. The CESAR effort is carried out in collaboration with world-class domain experts from leading universities, and in close coordination with other national laboratories and oil industry partners.

  15. NORTH HILL CREEK 3-D SEISMIC EXPLORATION PROJECT

    SciTech Connect

    Marc T. Eckels; David H. Suek; Denise H. Harrison; Paul J. Harrison

    2004-05-06

    Wind River Resources Corporation (WRRC) received a DOE grant in support of its proposal to acquire, process and interpret fifteen square miles of high-quality 3-D seismic data on non-allotted trust lands of the Uintah and Ouray (Ute) Indian Reservation, northeastern Utah, in 2000. Subsequent to receiving notice that its proposal would be funded, WRRC was able to add ten square miles of adjacent state and federal mineral acreage underlying tribal surface lands by arrangement with the operator of the Flat Rock Field. The twenty-five square mile 3-D seismic survey was conducted during the fall of 2000. The data were processed through the winter of 2000-2001, and initial interpretation took place during the spring of 2001. The initial interpretation identified multiple attractive drilling prospects, two of which were staked and permitted during the summer of 2001. The two initial wells were drilled in September and October of 2001. A deeper test was drilled in June of 2002. Subsequently a ten-well deep drilling evaluation program was conducted from October of 2002 through March 2004. The present report discusses the background of the project; design and execution of the 3-D seismic survey; processing and interpretation of the data; and drilling, completion and production results of a sample of the wells drilled on the basis of the interpreted survey. Fifteen wells have been drilled to test targets identified on the North Hill Creek 3-D Seismic Survey. None of these wildcat exploratory wells has been a dry hole, and several are among the best gas producers in Utah. The quality of the data produced by this first significant exploratory 3-D survey in the Uinta Basin has encouraged other operators to employ this technology. At least two additional 3-D seismic surveys have been completed in the vicinity of the North Hill Creek Survey, and five additional surveys are being planned for the 2004 field season. This project was successful in finding commercial oil, natural gas

  16. Seismic random noise attenuation via 3D block matching

    NASA Astrophysics Data System (ADS)

    Amani, Sajjad; Gholami, Ali; Javaheri Niestanak, Alireza

    2017-01-01

    The lack of signal to noise ratio increases the final errors of seismic interpretation. In the present study, we apply a new non-local transform domain method called "3 Dimensional Block Matching (3DBM)" for seismic random noise attenuation. Basically, 3DBM uses the similarities through the data for retrieving the amplitude of signal in a specific point in the f-x domain, and because of this, it is able to preserve discontinuities in the data such as fractures and faults. 3DBM considers each seismic profile as an image and thus it can be applied to both pre-stack and post-stack seismic data. It uses the block matching clustering method to gather similar blocks contained in 2D data into 3D groups in order to enhance the level of correlation in each 3D array. By applying a 2D transform and 1D transform (instead of a 3D transform) on each array, we can effectively attenuate the noise by shrinkage of the transform coefficients. The subsequent inverse 2D transform and inverse 1D transform yield estimates of all matched blocks. Finally, the random noise attenuated data is computed using the weighted average of all block estimates. We applied 3DBM on both synthetic and real pre-stack and post-stack seismic data and compared it with a Curvelet transform based denoising method which is one of the most powerful methods in this area. The results show that 3DBM method eventuates in higher signal to noise ratio, lower execution time and higher visual quality.

  17. 3D seismic imaging on massively parallel computers

    SciTech Connect

    Womble, D.E.; Ober, C.C.; Oldfield, R.

    1997-02-01

    The ability to image complex geologies such as salt domes in the Gulf of Mexico and thrusts in mountainous regions is a key to reducing the risk and cost associated with oil and gas exploration. Imaging these structures, however, is computationally expensive. Datasets can be terabytes in size, and the processing time required for the multiple iterations needed to produce a velocity model can take months, even with the massively parallel computers available today. Some algorithms, such as 3D, finite-difference, prestack, depth migration remain beyond the capacity of production seismic processing. Massively parallel processors (MPPs) and algorithms research are the tools that will enable this project to provide new seismic processing capabilities to the oil and gas industry. The goals of this work are to (1) develop finite-difference algorithms for 3D, prestack, depth migration; (2) develop efficient computational approaches for seismic imaging and for processing terabyte datasets on massively parallel computers; and (3) develop a modular, portable, seismic imaging code.

  18. Investigation of surface wave amplitudes in 3-D velocity and 3-D Q models

    NASA Astrophysics Data System (ADS)

    Ruan, Y.; Zhou, Y.

    2010-12-01

    It has been long recognized that seismic amplitudes depend on both wave speed structures and anelasticity (Q) structures. However, the effects of lateral heterogeneities in wave speed and Q structures on seismic amplitudes has not been well understood. We investigate the effects of 3-D wave speed and 3-D anelasticity (Q) structures on surface-wave amplitudes based upon wave propagation simulations of twelve globally-distributed earthquakes and 801 stations in Earth models with and without lateral heterogeneities in wave speed and anelasticity using a Spectral Element Method (SEM). Our tomographic-like 3-D Q models are converted from a velocity model S20RTS using a set of reasonable mineralogical parameters, assuming lateral perturbations in both velocity and Q are due to temperature perturbations. Surface-wave amplitude variations of SEM seismograms are measured in the period range of 50--200 s using boxcar taper, cosine taper and Slepian multi-tapers. We calculate ray-theoretical predictions of surface-wave amplitude perturbations due to elastic focusing, attenuation, and anelastic focusing which respectively depend upon the second spatial derivative (''roughness'') of perturbations in phase velocity, 1/Q, and the roughness of perturbations in 1/Q. Both numerical experiments and theoretical calculations show that (1) for short-period (~ 50 s) surface waves, the effects of amplitude attenuation due to 3-D Q structures are comparable with elastic focusing effects due to 3-D wave speed structures; and (2) for long-period (> 100 s) surface waves, the effects of attenuation become much weaker than elastic focusing; and (3) elastic focusing effects are correlated with anelastic focusing at all periods due to the correlation between velocity and Q models; and (4) amplitude perturbations are depend on measurement techniques and therefore cannot be directly compared with ray-theoretical predictions because ray theory does not account for the effects of measurement

  19. 3-D Seismic Tomography Survey at a Groundwater Contamination Site

    NASA Astrophysics Data System (ADS)

    Azaria, A.; Zelt, C.; Levander, A.

    2002-12-01

    As part of an ongoing environmental characterization project at Hill Air Force Base near Ogden, Utah, a 3-D seismic survey led by a team from Rice University was performed over a contaminated aquifer in 2000. This site contains significant amounts of dense non-aqueous phase liquids (DNAPLs) in a shallow aquifer less than ~15 m deep. The aquifer is bounded below by a clay aquiclude, in which a paleochannel acts as a trap for the contaminants. The overburden consists of Quaternary sands, gravels and clays. Imaging the structure of the paleochannel at depths up to 15 m is the main target of the survey. The four week experiment included 3-D reflection, 3-D refraction, checkshot surveys and vertical seismic profiles using wells up to 15m deep. Here we present traveltime tomography results from the 3-D refraction survey which consisted of 596 RefTek Texan recorders deployed uniformly in a stationary rectangular grid over an area of 95m by 36m. A shot from a .223 caliber rifle was fired 30cm from each receiver station, yielding a dataset with about 360,000 traces. The arrival times of the refracted waves were used in a 3-D tomographic inversion to image the seismic velocity structure of the study area. The iterative, nonlinear tomographic approach employs regularization to smooth the model perturbations with respect to a simple 1-D starting/reference model. The resulting velocity model shows that the near-surface velocity increases by roughly a factor of 5 in the upper 15m, from about 300m/s to 1500m/s. Cross-sections through the model show a north-south trending low-velocity feature interpreted to be the channel structure. The low-velocity feature is best viewed via depth slices which define an anomaly that roughly outlines the geometry of the buried paleo-channel based on well data. A comparison between the 3-D velocity model and time slices through a brute stack of the 3-D reflection data also show close agreement (see Dana et al. this session). Checkerboard tests

  20. Recovering physical property information from subduction plate boundaries using 3D full-waveform seismic inversion

    NASA Astrophysics Data System (ADS)

    Bell, R. E.; Morgan, J. V.; Warner, M.

    2013-12-01

    Our understanding of subduction margin seismogenesis has been revolutionised in the last couple of decades with the discovery that the size of the seismogenic zone may not be controlled simply by temperature and a broad spectrum of seismic behaviour exists from stick-slip to stable sliding. Laboratory and numerical experiments suggest that physical properties, particularly fluid pressure may play an important role in controlling the seismic behaviour of subduction margins. Although drilling can provide information on physical properties along subduction thrust faults at point locations at relatively shallow depths, correlations between physical properties and seismic velocity using rock physics relationships are required to resolve physical properties along the margin and down-dip. Therefore, high resolution seismic velocity models are key to recovering physical property information at subduction plate boundaries away from drill sites. 3D Full waveform inversion (FWI) is a technique pioneered by the oil industry to obtain high-resolution high-fidelity models of physical properties in the sub-surface. 3D FWI involves the inversion of low-frequency (>2 to <7 Hz), early arriving (principally transmitted) seismic data, to recover the macro (intermediate to long-wavelength) velocity structure. Although 2D FWI has been used to improve velocity models of subduction plate boundaries before, 3D FWI has not yet been attempted. 3D inversions have superior convergence and accuracy, as they sample the subsurface with multi-azimuth multiply-crossing wavefields. In this contribution we perform a suite of synthetic tests to investigate if 3D FWI could be used to better resolve physical property information along subduction margin plate boundaries using conventionally collected 3D seismic data. We base our analysis on the Muroto Basin area of the Nankai margin and investigate if the acquisition parameters and geometry of the subduction margin render 3D seismic data collected across

  1. Exploration 3-D Seismic Field Test/Native Tribes Initiative

    SciTech Connect

    Carroll, Herbert B.; Chen, K.C.; Guo, Genliang; Johnson, W.I.; Reeves,T.K.; Sharma,Bijon

    1999-04-27

    To determine current acquisition procedures and costs and to further the goals of the President's Initiative for Native Tribes, a seismic-survey project is to be conducted on Osage tribal lands. The goals of the program are to demonstrate the capabilities, costs, and effectiveness of 3-D seismic work in a small-operator setting and to determine the economics of such a survey. For these purposes, typical small-scale independent-operator practices are being followed and a shallow target chose in an area with a high concentration of independent operators. The results will be analyzed in detail to determine if there are improvements and/or innovations which can be easily introduced in field-acquisition procedures, in processing, or in data manipulation and interpretation to further reduce operating costs and to make the system still more active to the small-scale operator.

  2. Cash value of 3-D seismic to a producing field

    SciTech Connect

    Bligh, R.; Thompson, S.

    1996-05-01

    Recent years have produced many reservoir management examples guided by seismic where clear value in excess of cost can be demonstrated. One of these examples was a 3-D survey recorded in the winter of 1994 over the Wytch Farm oil field in southern England, operated by BP on behalf of a consortium, including Arco, Clyda, Premier, Goal and Purbeck. A joint BP-CGG case history of this survey was presented at the 1995 SEG Convention in Houston and will be repeated at the 1996 AAPG Convention in San Diego. A brief summary is provided in this paper.

  3. Parallel 3-D viscoelastic finite difference seismic modelling

    NASA Astrophysics Data System (ADS)

    Bohlen, Thomas

    2002-10-01

    Computational power has advanced to a state where we can begin to perform wavefield simulations for realistic (complex) 3-D earth models at frequencies of interest to both seismologists and engineers. On serial platforms, however, 3-D calculations are still limited to small grid sizes and short seismic wave traveltimes. To make use of the efficiency of network computers a parallel 3-D viscoelastic finite difference (FD) code is implemented which allows to distribute the work on several PCs or workstations connected via standard ethernet in an in-house network. By using the portable message passing interface standard (MPI) for the communication between processors, running times can be reduced and grid sizes can be increased significantly. Furthermore, the code shows good performance on massive parallel supercomputers which makes the computation of very large grids feasible. This implementation greatly expands the applicability of the 3-D elastic/viscoelastic finite-difference modelling technique by providing an efficient, portable and practical C-program.

  4. Stratigraphic and structural interpretation with 3-D seismic coherence

    SciTech Connect

    Bahorich, M.; Lopez, J.; Haskell, N.

    1996-12-31

    3-D seismic discontinuity is useful for identifying faults, stratigraphic features and the relationship between them. This paper covers the application of coherence technology to three basins; the Gulf of Mexico, the North Sea, aid the Ardmore Basin of Oklahoma. In the Gulf of Mexico, 3-D coherence data may be used to simultaneously view faults and stratigraphic features and therefore see the relationship between them. Coherence data reveal channels that avoid a structural high generated by a salt dome, Channels that change direction as they cross faults, radial faults adjacent to a salt dome, and complex and en-echelon faults. Since the coherence process is applied to non- interpreted seismic data, these features are available for viewing without the time or bias of interpretation. Coherence time slices from the Ardmore Basin of Oklahoma were compared with a horizon-dip map and a discrepancy in the fault patterns was noted. Further analysis revealed that subtle errors in the autopicking had created a false bend in a fault trace seen on the horizon-dip map. After correction, the horizon-dip map and coherence time slice indicated similar fault patterns. Since the coherence method is run on the raw seismic data, it provides a view of the faults that is not biased by the interpreter or horizon autopicker. In the North Sea, faults may exhibit meandering patterns that are easy to interpret on traditional time-slices where they cut perpendicular to stratigraphic bedding but are difficult to recognize where they cut parallel to bedding. The coherence technique images faults in any orientation equally well.

  5. Stratigraphic and structural interpretation with 3-D seismic coherence

    SciTech Connect

    Bahorich, M.; Lopez, J.; Haskell, N.; Nissen, S.; Poole, A.

    1996-06-01

    3-D seismic discontinuity is useful for identifying faults, stratigraphic features and the relationship between them. This paper covers the application of coherence technology to three basins; the Gulf of Mexico, the North Sea, and the Ardmore Basin of Oklahoma. In the Gulf of Mexico, 3-D coherence data may be used to simultaneously view faults and stratigraphic features and therefore see the relationship between them. Coherence data reveal channels that avoid a structural high generated by a salt dome, channels that change direction as they cross faults, radial faults adjacent to a salt dome, and complex and en-echelon faults. Since the coherence process is applied to non-interpreted seismic data, these features are available for viewing without the time or bias of interpretation. Coherence time slices from the Ardmore Basin of Oklahoma were compared with a horizon-dip map and a discrepancy in the fault patterns was noted. Further analysis revealed that subtle errors in the autopicking had created a false bend in a fault trace seen on the horizon-dip map. After correction, the horizon-dip map and coherence time slice indicated similar fault patterns. Since the coherence method is run on the raw seismic data, it provides a view of the faults that is not biased by the interpreter or horizon autopicker. In the North Sea, faults may exhibit meandering patterns that are easy to interpret on traditional time-slices where they cut perpendicular to stratigraphic bedding but are difficult to recognize where they cut parallel to bedding. The coherence technique images faults in any orientation equally well.

  6. Frio, Yegua objectives of E. Texas 3D seismic

    SciTech Connect

    1996-07-01

    Houston companies plan to explore deeper formations along the Sabine River on the Texas and Louisiana Gulf Coast. PetroGuard Co. Inc. and Jebco Seismic Inc., Houston, jointly secured a seismic and leasing option from Hankamer family et al. on about 120 sq miles in Newton County, Tex., and Calcasieu Parish, La. PetroGuard, which specializes in oilfield rehabilitation, has production experience in the area. Historic production in the area spans three major geologic trends: Oligocene Frio/Hackberry, downdip and mid-dip Eocene Yegua, and Eocene Wilcox. In the southern part of the area, to be explored first, the trends lie at 9,000--10,000 ft, 10,000--12,000 ft, and 14,000--15,000 ft, respectively. Output Exploration Co., an affiliate of Input/Output Inc., Houston, acquired from PetroGuard and Jebco all exploratory drilling rights in the option area. Output will conduct 3D seismic operations over nearly half the acreage this summer. Data acquisition started late this spring. Output plans to use a combination of a traditional land recording system and I/O`s new RSR 24 bit radio telemetry system because the area spans environments from dry land to swamp.

  7. Northern California Seismic Attenuation: 3-D Qp and Qs models

    NASA Astrophysics Data System (ADS)

    Eberhart-Phillips, D. M.

    2015-12-01

    The northern California crust exhibits a wide range of rock types and deformation processes which produce pronounced heterogeneity in regional attenuation. Using local earthquakes, 3-D Qp and Qs crustal models have been obtained for this region which includes the San Andreas fault system, the Central Valley, the Sierra Nevada batholith, and the Mendocino subduction volcanic system. Path attenuation t* values were determined from P and S spectra of 959 spatially distributed earthquakes, magnitude 2.5-6.0 from 2005-2014, using 1254 stations from NCEDC networks and IRIS Mendocino and Sierra Nevada temporary arrays. The t* data were used in Q inversions, using existing hypocenters and 3-D velocity models, with basic 10-km node spacing. The uneven data coverage was accounted for with linking of nodes into larger areas in order to provide useful Q images across the 3-D volume. The results at shallow depth (< 2 km) show very low Q in the Sacramento Delta, the Eureka area, and parts of the Bay Area. In the brittle crust, fault zones that have high seismicity exhibit low Q. In the lower crust, low Q is observed along fault zones that have large cumulative displacement and have experienced grain size reduction. Underlying active volcanic areas, low Q features are apparent below 20-km depth. Moderately high Q is associated with igneous rocks of the Sierra Nevada and Salinian block, while the Franciscan subduction complex shows moderately low Q. The most prominent high Q feature is related to the Great Valley Ophiolite.

  8. Seismic source inversion using Green's reciprocity and a 3-D structural model for the Japanese Islands

    NASA Astrophysics Data System (ADS)

    Simutė, S.; Fichtner, A.

    2015-12-01

    We present a feasibility study for seismic source inversions using a 3-D velocity model for the Japanese Islands. The approach involves numerically calculating 3-D Green's tensors, which is made efficient by exploiting Green's reciprocity. The rationale for 3-D seismic source inversion has several aspects. For structurally complex regions, such as the Japan area, it is necessary to account for 3-D Earth heterogeneities to prevent unknown structure polluting source solutions. In addition, earthquake source characterisation can serve as a means to delineate existing faults. Source parameters obtained for more realistic Earth models can then facilitate improvements in seismic tomography and early warning systems, which are particularly important for seismically active areas, such as Japan. We have created a database of numerically computed 3-D Green's reciprocals for a 40°× 40°× 600 km size area around the Japanese Archipelago for >150 broadband stations. For this we used a regional 3-D velocity model, recently obtained from full waveform inversion. The model includes attenuation and radial anisotropy and explains seismic waveform data for periods between 10 - 80 s generally well. The aim is to perform source inversions using the database of 3-D Green's tensors. As preliminary steps, we present initial concepts to address issues that are at the basis of our approach. We first investigate to which extent Green's reciprocity works in a discrete domain. Considering substantial amounts of computed Green's tensors we address storage requirements and file formatting. We discuss the importance of the initial source model, as an intelligent choice can substantially reduce the search volume. Possibilities to perform a Bayesian inversion and ways to move to finite source inversion are also explored.

  9. Intraplate Seismicity and Lithospheric Strength as Inferred from 3D Seismic Models

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Pollitz, F. F.; Ritsema, J.

    2014-12-01

    Focal mechanism studies and other stress indicators indicate that intraplate earthquakes in central and eastern North America are consistent with an ENE-WSW compressive stress field that acts on existing faults. Here we argue that either locally thinned lithosphere (as beneath the Reelfoot Rift, central US) or regional lithospheric thinning (as beneath the edge of the North American craton or the rifted continental margin) constitutes zones of relatively low lithospheric strength where crustal strain accumulates. We use seismic surface waves to determine the 3D shear-wave seismic velocity structure of the lithosphere, and find that the Reelfoot Rift is underlain by a zone with low mantle seismic velocities that extends to at least 200 km depth. Thus, the Reelfoot Rift, which hosts the New Madrid Seismic Zone, is unique among North American paleo-rifts in term of the properties in the mantle. We hypothesize that this low-velocity mantle volume is weaker than its surroundings and that the Reelfoot Rift consequently has relatively lower elastic plate thickness that would tend to concentrate tectonic stress within this zone. On a continental scale, the 3D velocity model clearly identifies an approximately 220-km-thick, high seismic velocity lithospheric root beneath the North America craton which has a low rate of crustal seismicity and very few events with Mw≥6. We attribute the relatively aseismic nature of the craton to dry, cold conditions within the cratonic lower crust and mantle lithosphere. Conversely, we find that a high proportion of intraplate events are concentrated around the pronounced lateral gradient in lithospheric thickness that surrounds the craton. We attribute this observation to a lateral decrease in lithospheric strength at the edge of the North American craton. This relationship between intraplate seismicity and lithospheric properties is apparent in maps that compare regional and continental lithospheric thickness with crustal seismicity. We

  10. Noise attenuation on 3D seismic project "Juzni Banat I"

    NASA Astrophysics Data System (ADS)

    Stojanovic, Vojislav; Milojevic, Slavka

    2017-04-01

    „Juzni Banat I" is a 3D land seismic survey area which covers more than 700 km2. The field is situated in a very complex area of southern Panonian basin. North-eastern part of the field is agricultural and the rest is sands. The thickness of the surface sands goes down to 200m deep which significantly attenuated the frequency of the signal. The dominant frequency varies from below 20Hz in sands to 30Hz in agricultural areas. Also there are urban zones and densely forested protected zone within sands which caused lower fold coverage. Survey is registered with wireless equipment and as a receiver single geophones were used. Every receiver was buried in the ground in order to decrease environmental noise. Due to all these field conditions followed with strong wind which is common in this area, the acquisition data have very strong noise, especially ground roll type of noise. It was the great effort to attenuate strong ground roll noise and to preserve and enhance the signal. This presentation shows how LIFT (Leading Intelligent Filter Technology) technology with different types of signal processing tools (amplitude scaling, time-variant band-limited suppression, frequency filtering, header manipulation…) suppresses noise on this very demanding survey.

  11. Drill site geohazard identification facilitated by rework of suitable existing 3D seismic data volumes

    SciTech Connect

    Cowlard, A.P.

    1996-12-31

    3D seismic volumes are increasingly being used to assist in the mapping and identification of drilling hazards. A method of reworking the 3D volume, termed the Short Offset method, is proposed which offers the benefit of optimized resolution in the shallow section and therefore provides the interpreter with an enhanced image of the near surface geology. The processing sequence contrasts markedly with conventional 3D processing and involves the inclusion of only near normal incidence traces. Two case histories are described which illustrate the application of the Short Offset method and its robustness even in conditions not conducive to enhancing frequency bandwidth. In summary, Short Offset reprocessing results in a product which offers considerably improved resolution when compared to a conventional 3D volume and far finer areal sampling when compared to a traditional 2D site survey thus providing the industry with a valuable tool for drilling hazard investigation.

  12. Towards Automated Seismic Moment Tensor Inversion in Australia Using 3D Structural Model

    NASA Astrophysics Data System (ADS)

    Hingee, M.; Tkalcic, H.; Fichtner, A.; Sambridge, M.; Kennett, B. L.; Gorbatov, A.

    2009-12-01

    There is significant seismic activity in the region around Australia, largely due to the plate boundaries to the north and to the east of the mainland. This seismicity poses serious seismic and tsunamigenic hazard in a wider region, and risk to coastal areas of Australia, and is monitored by Geoscience Australia (GA) using a network of permanent broadband seismometers within Australia. Earthquake and tsunami warning systems were established by the Australian Government and have been using the waveforms from the GA seismological network. The permanent instruments are augmented by non-GA seismic stations based both within and outside of Australia. In particular, seismic moment tensor (MT) solutions for events around Australia as well as local distances are useful for both warning systems and geophysical studies in general. These monitoring systems, however, currently use only one dimensional, spherically-symmetric models of the Earth for source parameter determination. Recently, a novel 3D model of Australia and the surrounding area has been developed from spectral element simulations [1], taking into account not only velocity heterogeneities, but also radial anisotropy and seismic attenuation. This development, inter alia, introduces the potential of providing significant improvements in MT solution accuracy. Allowing reliable MT solutions with reduced dependence on non-GA stations is a secondary advantage. We studied the feasibility of using 1D versus 3D structural models. The accuracy of the 3D model has been investigated, confirming that these models are in most cases superior to the 1D models. A full MT inversion method using a point source approximation was developed as the first step, keeping in mind that for more complex source time functions, a finite source inversion will be needed. Synthetic experiments have been performed with random noise added to the signal to test the code in the both 1D and 3D setting, using a precomputed library of structural Greens

  13. 3D seismic reverse time migration on GPGPU

    NASA Astrophysics Data System (ADS)

    Liu, Guofeng; Liu, Yaning; Ren, Li; Meng, Xiaohong

    2013-09-01

    Reverse time migration (RTM) is a powerful seismic imaging method for the interpretation of steep-dips and subsalt regions; however, implementation of the RTM method is computationally expensive. In this paper, we present a fast and computationally inexpensive implementation of RTM using a NVIDIA general purpose graphic processing unit (GPGPU) powered with Compute Unified Device Architecture (CUDA). To accomplish this, we introduced a random velocity boundary in the source propagation kernel. By creating a random velocity layer at the left, right, and bottom boundaries, the wave fields that encounter the boundary regions are pseudo-randomized. Reflections off the random layers have minimal coherent correlation in the reverse direction. This process eliminates the need to write the wave fields to a disk, which is important when using a GPU because of the limited bandwidth of the PCI-E that is connected to the CPU and GPU. There are four GPU kernels in the code: shot, receiver, modeling, and imaging. The shot and receiver insertion kernels are simple and are computed using a GPU because the wave fields reside in GPU's memory. The modeling kernel is computed using Micikevicius's tiling method, which uses shared memory to improve bandwidth usage in 2D and 3D finite difference problems. In the imaging kernel, we also use this tiling method. A Tesla C2050 GPU with 4 GB memory and 480 stream processing units was used to test the code. The shot and receiver modeling kernel occupancy achieved 85%, and the imaging kernel occupancy was 100%. This means that the code achieved a good level of optimization. A salt model test verified the correct and effective implementation of the GPU RTM code.

  14. Fluids emission and gas chimneys imaged in high-resolution 3D seismic: Investigating the role of sedimentary structures in controlling vertical fluid migration (offshore of Ceará-Potiguar sub-basin, Brazil).

    NASA Astrophysics Data System (ADS)

    Maestrelli, Daniele; Iacopini, David; Vittorio, Maselli

    2017-04-01

    Fluid emissions at seabed have been widely investigated during last years due to their potential in detecting new petroleum provinces and to their role in monitoring the environmental risk associated to CO2 storage and hydrocarbon leakage from the overburden. Fluid emission appears to be characterized by a variety of different processes and genetic mechanisms, and has been reported in different geological settings. We investigated a 45 by 25 km 3D seismic dataset located in the offshore Ceará state (Brazil), imaging the submarine slope system of the Potiguar sub-basin, part of the Ceará basin. The Paleogene sequence is characterized by a series of steep canyons acting as slope-bypass systems that force the transport of sediment basinward and promote the deposition in deepwater settings. The whole area seems to be affected by gravity driven processes in the form of turbidites and hyperpycnal flows that probably are responsible of the main submarine landslides observed and of the evolution of the canyons themselves. Bottom currents seem to play a key role in shaping the margin as well, by promoting the formation of sediment ridges and fields of sediment waves. In this setting, a series of widely distributed active pockmarks are observed both at the seabed and as paleo-pockmarks in the seismic subsurface, testifying the upward fluid migration and emission along gas chimneys and conduits. Active or recent pockmark varies from tens of meters up to about 2 km in diameters and are mainly circular to elliptical. A preliminary systematic mapping of those fluid escape features shows the strong control of the chutes and pools generated by fast turbidity currents on the chimney geometry pattern and fluid conduit. This evidence may suggest that the erosional/depositional features associated to turbidite sedimentation strongly control lateral permeability variations and, consequently, the vertical fluid migration.

  15. 3D Modelling of Seismically Active Parts of Underground Faults via Seismic Data Mining

    NASA Astrophysics Data System (ADS)

    Frantzeskakis, Theofanis; Konstantaras, Anthony

    2015-04-01

    During the last few years rapid steps have been taken towards drilling for oil in the western Mediterranean sea. Since most of the countries in the region benefit mainly from tourism and considering that the Mediterranean is a closed sea only replenishing its water once every ninety years careful measures are being taken to ensure safe drilling. In that concept this research work attempts to derive a three dimensional model of the seismically active parts of the underlying underground faults in areas of petroleum interest. For that purpose seismic spatio-temporal clustering has been applied to seismic data to identify potential distinct seismic regions in the area of interest. Results have been coalesced with two dimensional maps of underground faults from past surveys and seismic epicentres, having followed careful reallocation processing, have been used to provide information regarding the vertical extent of multiple underground faults in the region of interest. The end product is a three dimensional map of the possible underground location and extent of the seismically active parts of underground faults. Indexing terms: underground faults modelling, seismic data mining, 3D visualisation, active seismic source mapping, seismic hazard evaluation, dangerous phenomena modelling Acknowledgment This research work is supported by the ESPA Operational Programme, Education and Life Long Learning, Students Practical Placement Initiative. References [1] Alves, T.M., Kokinou, E. and Zodiatis, G.: 'A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins', Marine Pollution Bulletin, In Press, 2014 [2] Ciappa, A., Costabile, S.: 'Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea)', Marine Pollution Bulletin, vol. 84 (1-2), pp. 44-55, 2014 [3] Ganas, A., Karastathis, V., Moshou, A., Valkaniotis, S., Mouzakiotis

  16. Characterization of landslide geometry using 3D seismic refraction traveltime tomography

    NASA Astrophysics Data System (ADS)

    Samyn, K.; Travelletti, J.; Bitri, A.; Grandjean, G.; Malet, J. P.

    2012-04-01

    The geometry of the bedrock, internal layers and shear surfaces/bands controls the deformation pattern and the mechanisms of landslides. A challenge to progress in the forecast of landslide acceleration in terms of early-warning is therefore to characterize the 3D geometry of the unstable mass at a high level of spatial resolution, both in the horizontal and vertical directions, by integrating information from different surveying techniques. For such characterization, seismic investigations are potentially of a great interest. In the case of complex structures, the measure and the processing of seismic data need to be performed in 3D. The objective of this work is to present the implementation of a 3D seismic refraction traveltime tomography technique based on an existing 2D Simultaneous Iterative Reconstruction Technique (SIRT). First the processing algorithm is detailed and its performance is discussed, and second an application to the La Valette complex landslide is presented. Inversion of first-arrival traveltimes produces a 3D tomogram that underlines the presence of many areas characterized by low P-wave velocity of 500-1800 m.s-1. These low P-wave velocity structures result from the presence of reworked blocks, surficial cracks and in-depth fracture zones. These structures seem to extend to around 25 m in depth over a 80 x 130 m area. Based on borehole geotechnical data and previous geophysical investigations, an interface corresponding to an internal slip surface can be suspected near the isovalue of 1200 m.s-1 at a depth of -10 to -15 m. The stable substratum is characterized by higher values of P-wave velocity of 1800-3000 m.s-1. The features identified in the 3D tomogram allow to better (1) delineate the boundary between the landslide and the surrounding stable slopes, and (2) understand the morphological structures within the landslide at a hectometric scale. The integration of the 3D seismic tomography interpretation to previous geophysical

  17. 3D AUV Microseismic Implementation for Deepwater Seabed Investigations

    NASA Astrophysics Data System (ADS)

    George, R.; Taylor, M. W.; Gravely, J. G.

    2005-05-01

    Autonomous Underwater Vehicle (AUV) technology, developed commercially over the past 5 years, allows for the geophysical investigation of the seabed on the deepwater continental slope at resolutions, data densities and timelines not previously attainable. High-resolution geophysical systems normally employed on deepwater survey AUVs consist of multibeam bathymetry, side scan sonar and subbottom profiler. Inertial navigation allows positioning accuracies on the order of plus or minus 3 meters in depths up to 2,000 meters. C & C Technologies, Inc. owns and operates the C-Surveyor I AUV, which has collected more than 40,000 km of geohazard survey data on the continental slopes of the Gulf of Mexico, Mediterranean Sea, Brazil and West Africa. The oil and gas industry routinely engineers deepwater platform-mooring systems and other bottom founded subsea systems for exploration and production developments. Resolute subbottom imaging of the foundation zone in order to identify the near-seafloor geologic conditions at these deepwater development sites is critical in order to maintain system integrity. The paper describes the methodology and post-processing techniques used to create a high-resolution (2-8 kHz) 3D seismic cube from subbottom profiler data collected from an AUV system. Data examples of the multibeam bathymetry, side scan sonar and 2D seismic profiles will be provided to complement the results of the 3D seismic cube processing. Examples of inlines, crosslines, arbitrary lines, seafloor amplitude extraction and time slices are presented for the 4-meter binned data set. Advantages, disadvantages and suggested improvements for the survey acquisition technique and post processing are discussed.

  18. 3-D seismic velocity and attenuation structures in the geothermal field

    SciTech Connect

    Nugraha, Andri Dian; Syahputra, Ahmad; Fatkhan,; Sule, Rachmat

    2013-09-09

    We conducted delay time tomography to determine 3-D seismic velocity structures (Vp, Vs, and Vp/Vs ratio) using micro-seismic events in the geothermal field. The P-and S-wave arrival times of these micro-seismic events have been used as input for the tomographic inversion. Our preliminary seismic velocity results show that the subsurface condition of geothermal field can be fairly delineated the characteristic of reservoir. We then extended our understanding of the subsurface physical properties through determining of attenuation structures (Qp, Qs, and Qs/Qp ratio) using micro-seismic waveform. We combined seismic velocities and attenuation structures to get much better interpretation of the reservoir characteristic. Our preliminary attanuation structures results show reservoir characterization can be more clearly by using the 3-D attenuation model of Qp, Qs, and Qs/Qp ratio combined with 3-D seismic velocity model of Vp, Vs, and Vp/Vs ratio.

  19. Definition of subsurface stratigraphy, structure and rock properties from 3-D seismic data

    NASA Astrophysics Data System (ADS)

    Hart, Bruce S.

    1999-10-01

    This paper summarizes how three-dimensional (3-D) seismic technology is being used, primarily in the petroleum industry, to define subsurface structure, stratigraphy and rock properties. A 3-D seismic data volume: (a) provides a more accurate image of the subsurface than can be obtained with 2-D seismic methods; (b) is continuous, and so has a much greater spatial sampling than is obtained with 2-D seismic or other subsurface data (e.g., wells); and (c) can be viewed and interpreted interactively from a variety of perspectives, thus enhancing the interpreter's ability to generate an accurate description of subsurface features of interest. Seismic interpretation was once the almost exclusive realm of geophysicists, however, most 3-D seismic interpretation today is conducted by multidisciplinary teams that integrate geophysical, geological, petrophysical and engineering data and concepts into the 3-D seismic interpretation. These factors, plus proper survey design, help to increase the chances of success of a 3-D seismic interpretation project. Although there are cases where the technology is not appropriate or cannot be applied (for economic reasons or otherwise), the general success of 3-D seismic has led it to become a mainstay of the petroleum industry. The approach and technology, first developed in that industry, have potential applications in other applied and fundamental earth science disciplines, including mining, environmental geology, structural geology and stratigraphy.

  20. 3-D visualisation and interpretation of seismic attributes extracted from large 3-D seismic datasets: Subregional and prospect evaluation, deepwater Nigeria

    SciTech Connect

    Sola, M.; Haakon Nordby, L.; Dailey, D.V.; Duncan, E.A.

    1996-12-31

    High resolution 3-D visualization of horizon interpretation and seismic attributes from large 3-D seismic surveys in deepwater Nigeria has greatly enhanced the exploration team`s ability to quickly recognize prospective segments of subregional and prospect specific scale areas. Integrated workstation generated structure, isopach and extracted horizon consistent, interval and windowed attributes are particularly useful in illustrating the complex structural and stratigraphical prospectivity of deepwater Nigeria. Large 3-D seismic volumes acquired over 750 square kilometers can be manipulated within the visualization system with attribute tracking capability that allows for real time data interrogation and interpretation. As in classical seismic stratigraphic studies, pattern recognition is fundamental to effective depositions facies interpretation and reservoir model construction. The 3-D perspective enhances the data interpretation through clear representation of relative scale, spatial distribution and magnitude of attributes. In deepwater Nigeria, many prospective traps rely on an interplay between syndepositional structure and slope turbidite depositional systems. Reservoir systems in many prospects appear to be dominated by unconfined to moderately focused slope feeder channel facies. These units have spatially complex facies architecture with feeder channel axes separated by extensive interchannel areas. Structural culminations generally have a history of initial compressional folding with late in extensional collapse and accommodation faulting. The resulting complex trap configurations often have stacked reservoirs over intervals as thick as 1500 meters. Exploration, appraisal and development scenarios in these settings can be optimized by taking full advantage of integrating high resolution 3-D visualization and seismic workstation interpretation.

  1. 3-D visualisation and interpretation of seismic attributes extracted from large 3-D seismic datasets: Subregional and prospect evaluation, deepwater Nigeria

    SciTech Connect

    Sola, M.; Haakon Nordby, L.; Dailey, D.V.; Duncan, E.A. )

    1996-01-01

    High resolution 3-D visualization of horizon interpretation and seismic attributes from large 3-D seismic surveys in deepwater Nigeria has greatly enhanced the exploration team's ability to quickly recognize prospective segments of subregional and prospect specific scale areas. Integrated workstation generated structure, isopach and extracted horizon consistent, interval and windowed attributes are particularly useful in illustrating the complex structural and stratigraphical prospectivity of deepwater Nigeria. Large 3-D seismic volumes acquired over 750 square kilometers can be manipulated within the visualization system with attribute tracking capability that allows for real time data interrogation and interpretation. As in classical seismic stratigraphic studies, pattern recognition is fundamental to effective depositions facies interpretation and reservoir model construction. The 3-D perspective enhances the data interpretation through clear representation of relative scale, spatial distribution and magnitude of attributes. In deepwater Nigeria, many prospective traps rely on an interplay between syndepositional structure and slope turbidite depositional systems. Reservoir systems in many prospects appear to be dominated by unconfined to moderately focused slope feeder channel facies. These units have spatially complex facies architecture with feeder channel axes separated by extensive interchannel areas. Structural culminations generally have a history of initial compressional folding with late in extensional collapse and accommodation faulting. The resulting complex trap configurations often have stacked reservoirs over intervals as thick as 1500 meters. Exploration, appraisal and development scenarios in these settings can be optimized by taking full advantage of integrating high resolution 3-D visualization and seismic workstation interpretation.

  2. A 3D Seismic Case: Shooting around a CCS Drill Site

    NASA Astrophysics Data System (ADS)

    Wang, C.

    2013-12-01

    The reduction of carbon dioxide emission to lessen the global warming has become an important international issue in recent years. The CCS technique (Carbon-dioxide Capture and Storage) is among the most recommended methods. The capture of CO2 during its manufacturing process in the electric power plant and storing in the adjacent area is considered to be an economical and feasible choice. This research uses the 2D and 3D high-resolution seismic reflection method to investigate possible CCS sites along the coast in Taiwan. The site is near an electric power plant and is planned to be a CCS experiment laboratory. The main objective is to detect the proper geologic structure and to prepare the baseline data for the future CO2 monitoring. The size of the high-resolution method applied in this study is much smaller than that used in the oil exploration. The obtained high quality and high resolution data can resolve very detailed structures. The survey parameters in 2D are 4m interval, 240 channels. The bin size in 3D seismic is 8m x 4m, 288 channels. Both 2D and 3D used the Minivibe as a source with 40Hz geophones, and having an average of 30 folds. The 3D seismic survey was conducted around the planned drill site. A surrounding type of 3D data acquisition was taken with sources at outside and receivers at the center. Such a deployment design is quite suitable for the drill site investigation. The structural layer as thin as 4m is able to be detected even under a depth of 3000m. Such a high resolution allows us not only to estimate the structure, but also able to monitor the migration of CO 2 after storage. The results of seismic survey after comparing with a nearby borehole data show that : 1) the caprock is Chinshui shale which is at a depth of 880m to 1000m with a thickness about 120m, 2) the Nanchuang formation and Kueichulin formation with high porosity can be proper reservoir layers which are located at the depth between 1000m to 1700m. In conclusion, this site

  3. Thrust fault growth within accretionary wedges: New Insights from 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Orme, H.; Bell, R. E.; Jackson, C. A. L.

    2015-12-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. Previous studies have reported en-echelon thrust fault geometries from the NW part of the dataset, and have related this complex structure to seamount subduction. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. We also demonstrate that the majority of faults grew upward from the décollement, although there is some evidence for downward fault propagation. Our observations

  4. Local seismic hazard assessment in explosive volcanic settings by 3D numerical analyses

    NASA Astrophysics Data System (ADS)

    Razzano, Roberto; Pagliaroli, Alessandro; Moscatelli, Massimiliano; Gaudiosi, Iolanda; Avalle, Alessandra; Giallini, Silvia; Marcini, Marco; Polpetta, Federica; Simionato, Maurizio; Sirianni, Pietro; Sottili, Gianluca; Vignaroli, Gianluca; Bellanova, Jessica; Calamita, Giuseppe; Perrone, Angela; Piscitelli, Sabatino

    2017-04-01

    This work deals with the assessment of local seismic response in the explosive volcanic settings by reconstructing the subsoil model of the Stracciacappa maar (Sabatini Volcanic District, central Italy), whose pyroclastic succession records eruptive phases ended about 0.09 Ma ago. Heterogeneous characteristics of the Stracciacappa maar (stratification, structural setting, lithotypes, and thickness variation of depositional units) make it an ideal case history for understanding mechanisms and processes leading to modifications of amplitude-frequency-duration of seismic waves generated at earthquake sources and propagating through volcanic settings. New geological map and cross sections, constrained with recently acquired geotechnical and geophysical data, illustrate the complex geometric relationships among different depositional units forming the maar. A composite interfingering between internal lacustrine sediments and epiclastic debris, sourced from the rim, fills the crater floor; a 45 meters thick continuous coring borehole was drilled in the maar with sampling of undisturbed samples. Electrical Resistivity Tomography surveys and 2D passive seismic arrays were also carried out for constraining the geological model and the velocity profile of the S-waves, respectively. Single station noise measurements were collected in order to define natural amplification frequencies. Finally, the nonlinear cyclic soil behaviour was investigated through simple shear tests on the undisturbed samples. The collected dataset was used to define the subsoil model for 3D finite difference site response numerical analyses by using FLAC 3D software (ITASCA). Moreover, 1D and 2D numerical analyses were carried out for comparison purposes. Two different scenarios were selected as input motions: a moderate magnitude (volcanic event) and a high magnitude (tectonic event). Both earthquake scenarios revealed significant ground motion amplification (up to 15 in terms of spectral acceleration

  5. Assessing a 3D smoothed seismicity model of induced earthquakes

    NASA Astrophysics Data System (ADS)

    Zechar, Jeremy; Király, Eszter; Gischig, Valentin; Wiemer, Stefan

    2016-04-01

    As more energy exploration and extraction efforts cause earthquakes, it becomes increasingly important to control induced seismicity. Risk management schemes must be improved and should ultimately be based on near-real-time forecasting systems. With this goal in mind, we propose a test bench to evaluate models of induced seismicity based on metrics developed by the CSEP community. To illustrate the test bench, we consider a model based on the so-called seismogenic index and a rate decay; to produce three-dimensional forecasts, we smooth past earthquakes in space and time. We explore four variants of this model using the Basel 2006 and Soultz-sous-Forêts 2004 datasets to make short-term forecasts, test their consistency, and rank the model variants. Our results suggest that such a smoothed seismicity model is useful for forecasting induced seismicity within three days, and giving more weight to recent events improves forecast performance. Moreover, the location of the largest induced earthquake is forecast well by this model. Despite the good spatial performance, the model does not estimate the seismicity rate well: it frequently overestimates during stimulation and during the early post-stimulation period, and it systematically underestimates around shut-in. In this presentation, we also describe a robust estimate of information gain, a modification that can also benefit forecast experiments involving tectonic earthquakes.

  6. Using 3D visualization and seismic attributes to improve structural and stratigraphic resolution of reservoirs

    SciTech Connect

    Kerr, J. ); Jones, G.L. )

    1996-01-01

    Recent advances in hardware and software have given the interpreter and engineer new ways to view 3D seismic data and well bore information. Recent papers have also highlighted the use of various statistics and seismic attributes. By combining new 3D rendering technologies with recent trends in seismic analysis, the interpreter can improve the structural and stratigraphic resolution of hydrocarbon reservoirs. This paper gives several examples using 3D visualization to better define both the structural and stratigraphic aspects of several different structural types from around the world. Statistics, 3D visualization techniques and rapid animation are used to show complex faulting and detailed channel systems. These systems would be difficult to map using either 2D or 3D data with conventional interpretation techniques.

  7. Using 3D visualization and seismic attributes to improve structural and stratigraphic resolution of reservoirs

    SciTech Connect

    Kerr, J.; Jones, G.L.

    1996-12-31

    Recent advances in hardware and software have given the interpreter and engineer new ways to view 3D seismic data and well bore information. Recent papers have also highlighted the use of various statistics and seismic attributes. By combining new 3D rendering technologies with recent trends in seismic analysis, the interpreter can improve the structural and stratigraphic resolution of hydrocarbon reservoirs. This paper gives several examples using 3D visualization to better define both the structural and stratigraphic aspects of several different structural types from around the world. Statistics, 3D visualization techniques and rapid animation are used to show complex faulting and detailed channel systems. These systems would be difficult to map using either 2D or 3D data with conventional interpretation techniques.

  8. 3-D seismic response of buried pipelines laid through fault

    SciTech Connect

    Liang, J.W.

    1995-12-31

    An ideal model for the non-causative fault is put forward in which the fault is assumed to be composed by three horizontally adjacent soil media. Dynamic behaviors of pipelines laid through the fault is analyzed. Although simple, this model may qualitatively illustrate the accumulation of seismic waves in the fault, so illustrate the dynamic behaviors of the pipelines. The results show that, the fault is materially different from a two soil site even if the fault width is very narrow, and the dynamic behaviors of the pipelines laid through the fault are determined by the fault width, the stiffness ratio of the three soil media, and the type of the seismic waves.

  9. 3D Full Seismic Waveform Tomography of NW Turkey and Surroundings

    NASA Astrophysics Data System (ADS)

    Cubuk, Yesim; Fichtner, Andreas; Taymaz, Tuncay

    2015-04-01

    Northward collision of the Arabian plate with the Eurasian plate, and interaction of the motion between dynamic processes originated from the subduction of the African plate beneath the Aegean generated very complex tectonic structures in the study region. Western Turkey is among one of the most active extensional regions in the world and the study area is mainly located where the extensional Aegean and the right-lateral strike-slip North Anatolian Fault Zone (NAFZ) intersects. Therefore, the tectonic framework of the NW Turkey and the Marmara region is mainly characterized by the transition between the strike-slip tectonics to the extensional tectonics. The Sea of Marmara region has been subjected to several active and passive seismic investigations, nevertheless the accurate knowledge on the heterogeneity in the crust and upper mantle beneath the study area still remains enigmatic. On small-scale tomography problems, seismograms strongly reflect the effects of heterogeneities and the scattering properties of the Earth. Thus, the knowledge of high-resolution seismic imaging with an improved 3D radially anisotropic crustal model of the NW Turkey will enable better localization of earthquakes, identification of faults as well as the improvement of the seismic hazard assessment. For this purpose, we aim to develop 3D radially anisotropic subsurface structure of the Sea of Marmara and NW Turkey crust based on full waveform adjoint tomography method. The earthquake data were principally obtained from the Kandilli Observatory and Earthquake Research Institute (KOERI) and Earthquake Research Center (AFAD-DAD) database. In addition to this, some of the seismic waveform data extracted from the Hellenic Unified Seismic Network (HUSN) stations that are located within our study region were also used in this study. We have selected and simulated waveforms of earthquakes with magnitudes 4.0 ≤ Mw ≤ 6.7 occurred in the period between 2007-2014 to determine the 3D velocity

  10. PRISM3D: a preliminary 3D reference seismic model of the crust and upper mantle beneath Iberia

    NASA Astrophysics Data System (ADS)

    Arroucau, Pierre; Custódio, Susana; Civiero, Chiara; Dias, Nuno A.; Silveira, Graça

    2017-04-01

    Earthquake location and moment tensor inversion are usually performed assuming one-dimensional (1D), radially symmetric models of the Earth's seismic velocity field. In a region such as Iberia, that hypothesis may no longer be valid: its location combining a plate boundary context with a passive margin environment indeed results in the presence of mountain ranges and abyssal plains, and juxtaposes sedimentary basins, thickened, normal and thinned continental crust, oceanic material, and even, locally, exhumed mantle. Furthermore, earthquakes in the Gulf of Cadiz and in the Alboran Sea, respectively west and east of Gibraltar Strait, are known to occur in the upper mantle, which also presents lateral velocity variations. A three-dimensional (3D) seismic velocity model of the crust and upper mantle beneath Iberia therefore appears necessary for accurate travel time and waveform modeling, in order to account for lateral variations of topography, Moho depth and lithology, and improve earthquake location and source inversion. Here, we present a new 3D P- and S-wave velocity model for Iberia. The model spans a region ranging from 17W to 6E in longitude and 28N to 47N in latitude, and from 7km above to 250 km below sea level in depth, with a grid node spacing of 10 km in longitude and latitude, and 0.5 km in depth. It results from the compilation of existing -published and unpublished - local earthquake and teleseismic body wave tomographic models, earthquake and ambient noise surface wave as well as receiver function inversion studies, and active source seismic experiments. Moho depth is estimated by interpolation of results from receiver function and deep seismic sounding using the reversible jump algorithm. Crust and mantle velocity field are then obtained separately by weighted average of the compiled models. This new 3D model, which combines the most recent seismic structure studies in Iberia and its surroundings, forms a reliable basis for earthquake location and

  11. Efficient linear inversion of poststack seismic data with 3-D uncertainties

    NASA Astrophysics Data System (ADS)

    Zunino, Andrea; Mosegaard, Klaus

    2017-04-01

    Large amounts of reflection seismic data are routinely collected to investigate the subsurface. This demands for fast and reliable algorithms to invert the seismic data for desired properties, such as acoustic impedance or other physical properties. The algorithm for inversion, in case of linear forward model and Gaussian uncertainties, based on the so-called least squares criterion, is well known. However, when the amount of data to be inverted is large, the size of the matrices involved grows so much that it may become impossible even to store them on disk and so calculations become impractical. Usually, to circumvent this problem, some assumptions are made, such as that of uncorrelated uncertainties both on data and model parameters, which lead to diagonal covariance matrices, and that of spatial invariance of the system, and thus the convolution approach. These simplifications alleviate the computational burden and decrease tremendously the size of arrays to be stored in memory/disk. Nevertheless, lateral and vertical correlated uncertainties both on data and model parameters are disregarded with this strategy, as well as potential spatial variance of the forward operator, often resulting in "noisy" images of the subsurface because each seismic trace is treated independently. In this study, we propose a methodology which, based on the assumption of separability and taking advantage of some properties of Kronecker products, it formulates the linear inverse problem with taking into account 3-D uncertainties through an algorithm which requires a very low memory/storage capability and is computationally very efficient compared to the classical approach. The result is a complete characterization of the so-called posterior distribution in terms of mean model and covariance. With this strategy, we can take into account the 3-D, vertical and horizontal correlation of uncertainties both on the model parameters and on the observed data, improving the final result of

  12. Seismic waves in 3-D: from mantle asymmetries to reliable seismic hazard assessment

    NASA Astrophysics Data System (ADS)

    Panza, Giuliano F.; Romanelli, Fabio

    2014-10-01

    A global cross-section of the Earth parallel to the tectonic equator (TE) path, the great circle representing the equator of net lithosphere rotation, shows a difference in shear wave velocities between the western and eastern flanks of the three major oceanic rift basins. The low-velocity layer in the upper asthenosphere, at a depth range of 120 to 200 km, is assumed to represent the decoupling between the lithosphere and the underlying mantle. Along the TE-perturbed (TE-pert) path, a ubiquitous LVZ, about 1,000-km-wide and 100-km-thick, occurs in the asthenosphere. The existence of the TE-pert is a necessary prerequisite for the existence of a continuous global flow within the Earth. Ground-shaking scenarios were constructed using a scenario-based method for seismic hazard analysis (NDSHA), using realistic and duly validated synthetic time series, and generating a data bank of several thousands of seismograms that account for source, propagation, and site effects. Accordingly, with basic self-organized criticality concepts, NDSHA permits the integration of available information provided by the most updated seismological, geological, geophysical, and geotechnical databases for the site of interest, as well as advanced physical modeling techniques, to provide a reliable and robust background for the development of a design basis for cultural heritage and civil infrastructures. Estimates of seismic hazard obtained using the NDSHA and standard probabilistic approaches are compared for the Italian territory, and a case-study is discussed. In order to enable a reliable estimation of the ground motion response to an earthquake, three-dimensional velocity models have to be considered, resulting in a new, very efficient, analytical procedure for computing the broadband seismic wave-field in a 3-D anelastic Earth model.

  13. 3D seismic data interpretation of Boonsville Field, Texas

    NASA Astrophysics Data System (ADS)

    Alhakeem, Aamer Ali

    The Boonsville field is one of the largest gas fields in the US located in the Fort Worth Basin, north central Texas. The highest potential reservoirs reside in the Bend Conglomerate deposited during the Pennsylvanian. The Boonsville data set is prepared by the Bureau of Economic Geology at the University of Texas, Austin, as part of the secondary gas recovery program. The Boonsville field seismic data set covers an area of 5.5 mi2. It includes 38 wells data. The Bend Conglomerate is deposited in fluvio-deltaic transaction. It is subdivided into many genetic sequences which include depositions of sandy conglomerate representing the potential reserves in the Boonsville field. The geologic structure of the Boonsville field subsurface are visualized by constructing structure maps of Caddo, Davis, Runaway, Beans Cr, Vineyard, and Wade. The mapping includes time structure, depth structure, horizon slice, velocity maps, and isopach maps. Many anticlines and folds are illustrated. Karst collapse features are indicated specially in the lower Atoka. Dipping direction of the Bend Conglomerate horizons are changing from dipping toward north at the top to dipping toward east at the bottom. Stratigraphic interpretation of the Runaway Formation and the Vineyard Formation using well logs and seismic data integration showed presence of fluvial dominated channels, point bars, and a mouth bar. RMS amplitude maps are generated and used as direct hydrocarbon indicator for the targeted formations. As a result, bright spots are indicated and used to identify potential reservoirs. Petrophysical analysis is conducted to obtain gross, net pay, NGR, water saturation, shale volume, porosity, and gas formation factor. Volumetric calculations estimated 989.44 MMSCF as the recoverable original gas in-place for a prospect in the Runaway and 3.32 BSCF for a prospect in the Vineyard Formation.

  14. Time-lapse 3-D seismic imaging of shallow subsurface contaminant flow.

    PubMed

    McKenna, J; Sherlock, D; Evans, B

    2001-12-01

    This paper presents a physical modelling study outlining a technique whereby buoyant contaminant flow within water-saturated unconsolidated sand was remotely monitored utilizing the time-lapse 3-D (TL3-D) seismic response. The controlled temperature and pressure conditions, along with the high level of acquisition repeatability attainable using sandbox physical models, allow the TL3-D seismic response to pore fluid movement to be distinguished from all other effects. TL3-D seismic techniques are currently being developed to monitor hydrocarbon reserves within producing reservoirs in an endeavour to improve overall recovery. However, in many ways, sandbox models under atmospheric conditions more accurately simulate the shallow subsurface than petroleum reservoirs. For this reason, perhaps the greatest application for analogue sandbox modelling is to improve our understanding of shallow groundwater and environmental flow mechanisms. Two fluid flow simulations were conducted whereby air and kerosene were injected into separate water-saturated unconsolidated sand models. In both experiments, a base 3-D seismic volume was recorded and compared with six later monitor surveys recorded while the injection program was conducted. Normal incidence amplitude and P-wave velocity information were extracted from the TL3-D seismic data to provide visualization of contaminant migration. Reflection amplitudes displayed qualitative areal distribution of fluids when a suitable impedance contrast existed between pore fluids. TL3-D seismic reflection tomography can potentially monitor the change in areal distribution of fluid contaminants over time, indicating flow patterns. However, other research and this current work have not established a quantifiable relationship between either normal reflection amplitudes and attenuation and fluid saturation. Generally, different pore fluids will have unique seismic velocities due to differences in compressibility and density. The predictable

  15. SEISVIZ3D: Stereoscopic system for the representation of seismic data - Interpretation and Immersion

    NASA Astrophysics Data System (ADS)

    von Hartmann, Hartwig; Rilling, Stefan; Bogen, Manfred; Thomas, Rüdiger

    2015-04-01

    The seismic method is a valuable tool for getting 3D-images from the subsurface. Seismic data acquisition today is not only a topic for oil and gas exploration but is used also for geothermal exploration, inspections of nuclear waste sites and for scientific investigations. The system presented in this contribution may also have an impact on the visualization of 3D-data of other geophysical methods. 3D-seismic data can be displayed in different ways to give a spatial impression of the subsurface.They are a combination of individual vertical cuts, possibly linked to a cubical portion of the data volume, and the stereoscopic view of the seismic data. By these methods, the spatial perception for the structures and thus of the processes in the subsurface should be increased. Stereoscopic techniques are e. g. implemented in the CAVE and the WALL, both of which require a lot of space and high technical effort. The aim of the interpretation system shown here is stereoscopic visualization of seismic data at the workplace, i.e. at the personal workstation and monitor. The system was developed with following criteria in mind: • Fast rendering of large amounts of data so that a continuous view of the data when changing the viewing angle and the data section is possible, • defining areas in stereoscopic view to translate the spatial impression directly into an interpretation, • the development of an appropriate user interface, including head-tracking, for handling the increased degrees of freedom, • the possibility of collaboration, i.e. teamwork and idea exchange with the simultaneous viewing of a scene at remote locations. The possibilities offered by the use of a stereoscopic system do not replace a conventional interpretation workflow. Rather they have to be implemented into it as an additional step. The amplitude distribution of the seismic data is a challenge for the stereoscopic display because the opacity level and the scaling and selection of the data have to

  16. 3D finite-difference seismic migration with parallel computers

    SciTech Connect

    Ober, C.C.; Gjertsen, R.; Minkoff, S.; Womble, D.E.

    1998-11-01

    The ability to image complex geologies such as salt domes in the Gulf of Mexico and thrusts in mountainous regions is essential for reducing the risk associated with oil exploration. Imaging these structures, however, is computationally expensive as datasets can be terabytes in size. Traditional ray-tracing migration methods cannot handle complex velocity variations commonly found near such salt structures. Instead the authors use the full 3D acoustic wave equation, discretized via a finite difference algorithm. They reduce the cost of solving the apraxial wave equation by a number of numerical techniques including the method of fractional steps and pipelining the tridiagonal solves. The imaging code, Salvo, uses both frequency parallelism (generally 90% efficient) and spatial parallelism (65% efficient). Salvo has been tested on synthetic and real data and produces clear images of the subsurface even beneath complicated salt structures.

  17. Salt distribution in the Louisiana South Additions area from 3D seismic data

    SciTech Connect

    Jamieson, G.A.

    1996-12-31

    This paper outlines some preliminary observations based on a large interpretation project that was carried out with a grid of 3D time migrated seismic data, covering over 7,500 mi{sup 2} of the South Additions region of offshore Louisiana. Depth migrated data, covering a smaller subset of the study area, was also utilized in the interpretation. Top and base of salt were interpreted and the resulting maps have identified patterns of salt and weld geometry that show some regional trends. Historically, 2D time migrated seismic has been the primary dataset of most of the published regional salt studies. This paper focuses on areas where 3D time migrated data potentially shows most improvement over 2D data, specifically in the subsalt regions. In particular, relationships between base-of-salt keels, welds, basins, regional faulting and basement architecture are investigated. A generalized model is outlined to help explain the current salt geometry in the study area and comparisons are made with recently published salt evolution models.

  18. Poor boy 3D seismic effort yields South Central Kentucky discovery

    SciTech Connect

    Hanratty, M.

    1996-11-04

    Clinton County, Ky., is on the eastern flank of the Cincinnati arch and the western edge of the Appalachian basin and the Pine Mountain overthrust. Clinton County has long been known for high volume fractured carbonate wells. The discovery of these fractured reservoir, unfortunately, has historically been serendipitous. The author currently uses 2D seismic and satellite imagery to design 3D high resolution seismic shoots. This method has proven to be the most efficient and is the core of his program. The paper describes exploration methods, seismic acquisition, well data base, and seismic interpretation.

  19. Experimental investigation on a novel 3D isolator made of shape memory alloy pseudo-rubber

    NASA Astrophysics Data System (ADS)

    Li, Su-chao; Guo, An-xin; Mao, Chen-xi; Li, Hui; Zhao, Yagebai

    2015-04-01

    Base isolation technology has been widely theoretically and experimentally investigated, and it has also been verified through many severe earthquakes. Three dimensional (3-D) isolation technology was proposed several years ago, and the 3-D isolation theory has well developed till now. However, the development of 3-D isolation technology was deeply affected by the 3-D isolator devices. Many presented 3-D isolators are generally made up of complicated components, such as rubber, springs, dampers or theirs combinations. These isolators have some problem in certain extent, such as difficult fabrication process or little energy dissipation ability along the vertical direction. This paper presents a novel 3- D isolator which is made up of martensitic shape memory alloy wires through weaving, rolling, and punching. Mechanical properties of 3-D shape memory alloy pseudo-rubber isolator (SMAPRI) are investigated including compression, shear, and compression-shear loading with different frequencies and amplitudes. The mechanical behavior of isolators with different parameters is also compared. Accordingly, the mechanism resulting in the above differences is also analyzed. Experimental results indicated that 3-D SMAPRI has good mechanical properties and energy dissipation ability along both of horizontal and vertical direction. The fabrication process of the proposed 3-D isolator is relatively easy and the mechanism of isolation is clearer than the traditional 3-D isolators. Therefore, this new kind of 3-D isolator has good potentiality in both of seismic isolation for civil infrastructures and industrial isolation for important or precision equipment.

  20. Numerical Investigation of 3-D Separation: DNS, LES and URANS

    DTIC Science & Technology

    2010-05-01

    Final Report Numerical Investigation of 3-D Separation: DNS, LES and URANS Office of Naval Research Contract number: N00014-07-1-0401 Program...COVERED (From - To) 12/11/2006-12/31/2009 4. TITLE AND SUBTITLE Numerical Investigation of 3-D Separation: DNS, LES and URANS 5a. CONTRACT NUMBER

  1. Asperities Interaction Through Subsequent Seismic Cycles: Insights From 3d Analog Models

    NASA Astrophysics Data System (ADS)

    Corbi, F.; Funiciello, F.; Brizzi, S.; Lallemand, S.

    2016-12-01

    Asperities synchronization is the key mechanism responsible for earthquakes growth to hundreds of km in length and, in turn, the genesis of devastating mega-events. Hypothesis on how asperities interact during earthquakes have been proposed. However, the asperities' behavior during subsequent seismic cycles is still not fully understood due to the limited observations. Here we tackle this argument using 3D analog models embedding two asperities separated by a barrier of variable width D. Our models have the advantage of reproducing tens of seismic cycles in a simplified but physically self-consistent setting. Spontaneously nucleating ruptures propagating along the plates interface are observed. Rupture behavior, earthquake magnitude Mw and backslip/slip ratio are investigated as a function of D. The experimental results show that the percentage of synchronized asperities ruptures is inversely related with D. Under the experimental conditions, a permanent barrier is observed when D is larger than a scaled-to-nature value of about 50 km. The maximum earthquake magnitude decreases as a function of D while the backslip/slip ratio has an opposite trend. These observations provide insights for seismic hazard assessment shedding light on the conditions that may promote asperities synchronization.

  2. Seismic moment tensor inversion using a 3-D structural model: applications for the Australian region

    NASA Astrophysics Data System (ADS)

    Hingee, Myall; Tkalčić, Hrvoje; Fichtner, Andreas; Sambridge, Malcolm

    2011-02-01

    There is significant seismic activity in the region around Australia, largely due to the plate boundaries to the north and to the east of the mainland. This activity results in serious seismic and tsunami hazard in the coastal areas of Australia. Hence seismicity is and will be monitored in real time by Geoscience Australia (GA), which uses a network of permanent broadband seismometers. Seismic moment tensor (MT) solutions are currently determined using 1-D, radially symmetric models of Earth and this requires augmentation by recording stations located outside of Australia. A 3-D model of the Australian continent developed recently using full waveform tomography now offers the opportunity to significantly improve the determination of MT solutions of earthquakes from tectonically active regions. A complete-waveform, time-domain MT inversion method has been developed using a point-source approximation. A series of synthetic tests using first a 1-D and then a 3-D structural model has been performed. The feasibility of deploying 3-D versus 1-D Earth structure for the inversion of seismic data has been studied and the advantages of using the 3-D structural model were illustrated with examples. The 3-D model is superior to the 1-D model, as a number of sensitivity tests show. The ultimate goal of this work is an automated MT inversion system in Australia relying on GA and other international stations, although more work remains to be done before the full implementation of such a scheme in real time.

  3. Understanding North Texas Seismicity: A Joint Analysis of Seismic Data and 3D Pore Pressure Modeling

    NASA Astrophysics Data System (ADS)

    DeShon, H. R.; Hornbach, M. J.; Ellsworth, W. L.; Oldham, H. R.; Hayward, C.; Stump, B. W.; Frohlich, C.; Olson, J. E.; Luetgert, J. H.

    2014-12-01

    In November 2013, a series of earthquakes began along a mapped ancient fault system near Azle, Texas. The Azle events are the third felt earthquake sequence in the Fort Worth (Barnett Shale) Basin since 2008, and several production and injection wells in the area are drilled to depths near the recent seismic activity. Understanding if and/or how injection and removal of fluids in the crystalline crust reactivates faults have important implications for seismology, the energy industry, and society. We assessed whether the Azle earthquakes were induced using a joint analysis of the earthquake data, subsurface geology and fault structure, and 3D pore pressure modeling. Using a 12-station temporary seismic deployment, we have recorded and located >300 events large enough to be recorded on multiple stations and 1000s of events during periods of swarm activity. High-resolution locations and focal mechanisms indicate that events occurred on NE-SW trending, steeply dipping normal faults associated with the southern end of the Newark East Fault Zone with hypocenters between 2-8 km depth. We considered multiple causes that might have changed stress along this system. Earthquakes resulting from natural processes, though perhaps unlikely in this historically inactive region, can be neither ruled out nor confirmed due to lack of information on the natural stress state of these faults. Analysis of lake and groundwater variations near Azle showed that no significant stress changes occurred prior to or during the earthquake sequence. In contrast, analysis of pore-pressure models shows that the combination of formation water production and wastewater injection near the fault could have caused pressure increases that induced earthquakes on near-critically stressed faults.

  4. Present-day Mars' Seismicity Predicted from 3-D Thermal Evolution Models of Interior Dynamics

    NASA Astrophysics Data System (ADS)

    Knapmeyer, M.; Plesa, A. C.; Golombek, M.

    2016-12-01

    The InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission, to be launched in 2018, will carry the first in-situ seismic and heat flow instruments as well as a precision tracking on Mars. This Discovery-class mission will perform the most comprehensive geophysical investigation of the planet and provide an important baseline to constrain the present-day interior structure and heat budget of the planet, and, in turn, the thermal and chemical evolution of its interior. As the InSight lander will perform the measurements at a single location, numerical simulations of planetary interiors will greatly help to interpret the data in a global context. In this study we have used a series of numerical models of thermal evolution in a 3-D spherical geometry to assess the magnitude of present-day Mars seismicity. Our models assume a fixed crust with a variable thickness as inferred from gravity and topography data, that is enriched in radiogenic heat sources according to the surface abundances inferred from gamma-ray measurements. We test a diversity of parameters by varying the mantle reference viscosity as well as the depth-dependence of the viscosity, considering constant and variable thermal expansivity, varying the crustal thermal conductivity and the size of the core [1]. Our results predict an annual moment release between 1.60 x 1016 Nm and 5.46 x 1018 Nm similar to the values presented previously in [2] and [3]. However, while [2] used a mapping of tectonic surface faults to predict the spatial distribution of epicenters, we derive the distribution from the thermal evolution. Besides the Null-Hypothesis of a uniform distribution and the model of [2], this provides a new, self-consistent, competing hypothesis for both the amount and distribution of seismicity on Mars. [1] Plesa et al., LPSC, 2016 [2] Knapmeyer et al., JGR, 2006 [3] Golombek et al., Science 1992; LPSC 2002

  5. Q AS A LITHOLOGICAL/HYDROCARBON INDICATOR: FROM FULL WAVEFORM SONIC TO 3D SURFACE SEISMIC

    SciTech Connect

    Jorge O. Parra; C.L. Hackert; L. Wilson; H.A. Collier; J. Todd Thomas

    2006-03-31

    The goal of this project was to develop a method to exploit viscoelastic rock and fluid properties to greatly enhance the sensitivity of surface seismic measurements to the presence of hydrocarbon saturation. To reach the objective, Southwest Research Institute scientists used well log, lithology, production, and 3D seismic data from an oil reservoir located on the Waggoner Ranch in north central Texas. The project was organized in three phases. In the first phase, we applied modeling techniques to investigate seismic- and acoustic-frequency wave attenuation and its effect on observable wave attributes. We also gathered existing data and acquired new data from the Waggoner Ranch field, so that all needed information was in place for the second phase. During the second phase, we developed methods to extract attenuation from borehole acoustic and surface seismic data. These methods were tested on synthetic data constructed from realistic models and real data. In the third and final phase of the project, we applied this technology to a full data set from the Waggoner site. The results presented in this Final Report show that geological conditions at the site did not allow us to obtain interpretable results from the Q processing algorithm for 3D seismic data. However, the Q-log processing algorithm was successfully applied to full waveform sonic data from the Waggoner site. A significant part of this project was technology transfer. We have published several papers and conducted presentations at professional conferences. In particular, we presented the Q-log algorithm and applications at the Society of Exploration Geophysicists (SEG) Development and Production Forum in Austin, Texas, in May 2005. The presentation attracted significant interest from the attendees and, at the request of the SEG delegates, it was placed on the Southwest Research Institute Internet site. The presentation can be obtained from the following link: http://www.swri.org/4org/d15/elecsys

  6. 3D Tromso survey planning: Cost efficiency through seismic data quality

    SciTech Connect

    Savini, L.; La Bella, G.; Ronchitelli, G.; Seldal, J.

    1996-12-31

    The approach described in this case history allows for the production of a full 3D dataset in order to solve the interpretation problems of the area at reduced cost. The structural definition of the main prospects in the area was unclear, mainly due to the poor quality of 2D seismic data. The committed 2D seismic survey would have probably supplied a seismic-data set of slightly better quality, but on the other hand, there would not have been a suitable improvement in the imaging of the main prospects. In an attempt to overcome these problems, an Explorative 3D survey was planned. In order to ensure a proper quality of the 3D dataset, an integrated approach to the acquisition and processing planning was adopted. Acquisition was carried out utilizing skipped configuration capable of acquiring 12 CMP lines for each sail line with a considerable reduction in cost.

  7. Deep 3-D seismic reflection imaging of Precambrian sills in the crystalline crust of Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Welford, Joanna Kim

    2005-07-01

    Using deep 3-D seismic reflection datasets collected by the Canadian petroleum exploration industry in southwestern and northwestern Alberta, the Head-Smashed-In and Winagami Precambrian sill complexes within the crystalline upper crust, previously identified on Lithoprobe 2-D multichannel reflection lines, are investigated to determine their 3-D geometries and reflective characteristics. During seismic processing of the dataset in southwestern Alberta, a recently developed wavelet-based method, Physical Wavelet Frame Denoising, is applied and shown to successfully suppress ground roll contamination while preserving low frequency signals from deeper structures. A new 3-D empirical trace interpolation scheme, DSInt, is developed to address the problem of spatial aliasing associated with 3-D data acquisition. Results from applying the algorithm to both datasets are comparable to available interpolation codes while allowing for greater flexibility in the handling of irregular acquisition geometries and interpolated trace headers. Evidence of the Head-Smashed-In reflector in southwestern Alberta is obtained using a dataset acquired to 8 s TWTT (approx. 24 km depth). From locally coherent, discontinuous pockets of basement reflectivity, the dataset appears to image the tapering western edge of the deep reflections imaged by Lithoprobe. A statistical approach of tracking reflectivity is developed and applied to obtain the spatial and temporal distribution of reflections. Simple 1-D forward modelling results reveal that the brightest reflections likely arise from a 50 to 150 m thick body of high density/high velocity material although variations in the amplitudes and lateral distribution of the reflections indicate that the thickness of the sills is laterally variable. Thus, the results are consistent with imaging the tapering edge of the sill complex. Clear evidence of the Winagami reflection sequence in northwestern Alberta, emerges from the second dataset acquired to 5

  8. 3D seismic data de-noising and reconstruction using Multichannel Time Slice Singular Spectrum Analysis

    NASA Astrophysics Data System (ADS)

    Rekapalli, Rajesh; Tiwari, R. K.; Sen, Mrinal K.; Vedanti, Nimisha

    2017-05-01

    Noises and data gaps complicate the seismic data processing and subsequently cause difficulties in the geological interpretation. We discuss a recent development and application of the Multi-channel Time Slice Singular Spectrum Analysis (MTSSSA) for 3D seismic data de-noising in time domain. In addition, L1 norm based simultaneous data gap filling of 3D seismic data using MTSSSA also discussed. We discriminated the noises from single individual time slices of 3D volumes by analyzing Eigen triplets of the trajectory matrix. We first tested the efficacy of the method on 3D synthetic seismic data contaminated with noise and then applied to the post stack seismic reflection data acquired from the Sleipner CO2 storage site (pre and post CO2 injection) from Norway. Our analysis suggests that the MTSSSA algorithm is efficient to enhance the S/N for better identification of amplitude anomalies along with simultaneous data gap filling. The bright spots identified in the de-noised data indicate upward migration of CO2 towards the top of the Utsira formation. The reflections identified applying MTSSSA to pre and post injection data correlate well with the geology of the Southern Viking Graben (SVG).

  9. Application of neural networks for identification of faults in a 3D seismic survey offshore Tunisia

    NASA Astrophysics Data System (ADS)

    Mastouri, Raja; Marchant, Robin; Marillier, François; Jaboyedoff, Michel; Bouaziz, Samir

    2013-04-01

    The Kerkennah High area (offshore Tunisia) is dominated by series of horst and grabens resulting from multiple tectonic events and multiphase stress (extension, compression, translation). In order to decipher this complex structural history from a 3D seismic survey, a neural network is applied to extract a fault-cube from the amplitude data (which does not image faults directly). The neural network transforms seismic attributes into a new 3D data cube in which faults are highlighted. This technique comprises the following steps. First, we compute several seismic attributes (dip-steering similarity, curvature, frequency, ridge and fault enhancement filters…) that enhance different aspects of the seismic data related to faulting. In a second step, a number of points in the seismic data are selected as representative of either faults or areas devoid of faults. These points are tested by the artificial neural network to determine the range in which the different attributes are representative of faults or not. Based on this learning phase, the neural network is then applied to the entire 3D seismic cube to produce a fault-cube that contains only faults which contrast and continuity have been enhance.

  10. Thrust fault segmentation and downward fault propagation in accretionary wedges: New Insights from 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Orme, Haydn; Bell, Rebecca; Jackson, Christopher

    2016-04-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. Although we often assume imbricate faults are likely to have propagated upwards from the décollement we show strong evidence for fault nucleation at shallow depths and downward propagation to intersect the décollement. The complex fault interactions documented here have implications for hydraulic compartmentalisation and pore

  11. Automatic detection of karstic sinkholes in seismic 3D images using circular Hough transform

    NASA Astrophysics Data System (ADS)

    Heydari Parchkoohi, Mostafa; Keshavarz Farajkhah, Nasser; Salimi Delshad, Meysam

    2015-10-01

    More than 30% of hydrocarbon reservoirs are reported in carbonates that mostly include evidence of fractures and karstification. Generally, the detection of karstic sinkholes prognosticate good quality hydrocarbon reservoirs where looser sediments fill the holes penetrating hard limestone and the overburden pressure on infill sediments is mostly tolerated by their sturdier surrounding structure. They are also useful for the detection of erosional surfaces in seismic stratigraphic studies and imply possible relative sea level fall at the time of establishment. Karstic sinkholes are identified straightforwardly by using seismic geometric attributes (e.g. coherency, curvature) in which lateral variations are much more emphasized with respect to the original 3D seismic image. Then, seismic interpreters rely on their visual skills and experience in detecting roughly round objects in seismic attribute maps. In this paper, we introduce an image processing workflow to enhance selective edges in seismic attribute volumes stemming from karstic sinkholes and finally locate them in a high quality 3D seismic image by using circular Hough transform. Afterwards, we present a case study from an on-shore oilfield in southwest Iran, in which the proposed algorithm is applied and karstic sinkholes are traced.

  12. Seismic Activity Seen Through Evolution of the Hurst Exponent Model in 3D

    NASA Astrophysics Data System (ADS)

    Patiño Ortiz, J.; Carreño Aguilera, R.; Balankin, A. S.; Patiño Ortiz, M.; Tovar Rodriguez, J. C.; Acevedo Mosqueda, M. A.; Martinez Cruz, M. A.; Yu, Wen

    2016-10-01

    The dynamics seismic activity occurred in the Cocos Plate - Mexico is analyzed through the evolution of Hurst exponent and 3D fractal dimension, under the mathematical fractal structure based on seismic activity time series, taking into account the magnitude (M) as the main parameter to be estimated. The seismic activity time series and, annual intervals are considered first for finding the Hurst exponent of each year since 1988 (the year in which the database is consistent) until 2012, and then the following years are accumulated describing the cumulative Hurst exponent. The seismic activity description is based on Cocos Plate data information; during a period conform from 1 January 1988 to 31 December 2012. Analyses were performed following methods, mainly considering that the Hurst exponent analysis provides the ability to find the seismicity behavior time-space, described by parameters obtained under the fractal dimension and complex systems.

  13. Areal 3-D seismic technique for reservoir delineation: Case history from offshore Niger Delta

    SciTech Connect

    Idowu, A.O. )

    1993-02-01

    In the 1950s, early exploration period in the Niger Delta witnessed the use of 2-D (two dimensional) seismic reflection method which adequate for imaging large subsurface geologic features including growth faulting and roll-over anticlines. This technique involves the Common-Depth-Point method (CDP) which acquires a plane of seismic information in distance along the surface and in time into the geological section, and is used to improve the signal-to-noise (S/N) ratio, to remove multiples and consequently give a representation of the subsurface particularly if the data are collected up- or downdip. By mid-1980s, the obvious geological structures have, in general, been discovered and it became necessary to adopt a more sophisticated technique such as the 3-D (three dimensional) seismic method to delineate more subtle reservoirs and resolve complex fault patterns in order to aid exploration as well as facilitate efficient field development. The case history discussed in this paper involves the use of areal 3-D seismic method for delineating the reservoir characterization of the O-field located in a shallow water area of the western Niger Delta. The areal 3-D seismic technique is superior to the earlier CDP method in that a cube of seismic data can be collected in two dimensions in space and one in time by a variety of techniques including the swath seismic shooting pattern adopted for gathering the 3-D data for the O-field's reservoir which involves the line of sources. The objective is to adequately sample the subsurface so that changes in various parameters such as the amplitude phase or power in the siesmic signal or velocity of propagation can be mapped areally and interpreted as an indication of changes in the physical properties of the rock matrix.

  14. High Resolution Near Surface 3D Seismic Experiments: A Carbonate Platform vs. a Siliciclastic Sequence

    NASA Astrophysics Data System (ADS)

    Filippidou, N.; Drijkoningen, G.; Braaksma, H.; Verwer, K.; Kenter, J.

    2005-05-01

    Interest in high-resolution 3D seismic experiments for imaging shallow targets has increased over the past years. Many case studies presented, show that producing clear seismic images with this non-evasive method, is still a challenge. We use two test-sites where nearby outcrops are present so that an accurate geological model can be built and the seismic result validated. The first so-called natural field laboratory is located in Boulonnais (N. France). It is an upper Jurassic siliciclastic sequence; age equivalent of the source rock of N. Sea. The second one is located in Cap Blanc,to the southwest of the Mallorca island(Spain); depicting an excellent example of Miocene prograding reef platform (Llucmajor Platform); it is a textbook analog for carbonate reservoirs. In both cases, the multidisciplinary experiment included the use of multicomponent and quasi- or 3D seismic recordings. The target depth does not exceed 120m. Vertical and shear portable vibrators were used as source. In the center of the setups, boreholes were drilled and Vertical Seismic Profiles were shot, along with core and borehole measurements both in situ and in the laboratory. These two geologically different sites, with different seismic stratigraphy have provided us with exceptionally high resolution seismic images. In general seismic data was processed more or less following standard procedures, a few innovative techniques on the Mallorca data, as rotation of horizontal components, 3D F-K filter and addition of parallel profiles, have improved the seismic image. In this paper we discuss the basic differences as seen on the seismic sections. The Boulonnais data present highly continuous reflection patterns of extremenly high resolution. This facilitated a high resolution stratigraphic description. Results from the VSP showed substantial wave energy attenuation. However, the high-fold (330 traces ) Mallorca seismic experiment returned a rather discontinuous pattern of possible reflectors

  15. A Geo-referenced 3D model of the Juan de Fuca Slab and associated seismicity

    USGS Publications Warehouse

    Blair, J.L.; McCrory, P.A.; Oppenheimer, D.H.; Waldhauser, F.

    2011-01-01

    We present a Geographic Information System (GIS) of a new 3-dimensional (3D) model of the subducted Juan de Fuca Plate beneath western North America and associated seismicity of the Cascadia subduction system. The geo-referenced 3D model was constructed from weighted control points that integrate depth information from hypocenter locations and regional seismic velocity studies. We used the 3D model to differentiate earthquakes that occur above the Juan de Fuca Plate surface from earthquakes that occur below the plate surface. This GIS project of the Cascadia subduction system supersedes the one previously published by McCrory and others (2006). Our new slab model updates the model with new constraints. The most significant updates to the model include: (1) weighted control points to incorporate spatial uncertainty, (2) an additional gridded slab surface based on the Generic Mapping Tools (GMT) Surface program which constructs surfaces based on splines in tension (see expanded description below), (3) double-differenced hypocenter locations in northern California to better constrain slab location there, and (4) revised slab shape based on new hypocenter profiles that incorporate routine depth uncertainties as well as data from new seismic-reflection and seismic-refraction studies. We also provide a 3D fly-through animation of the model for use as a visualization tool.

  16. 3-D cross-gradient joint inversion of seismic refraction and DC resistivity data

    NASA Astrophysics Data System (ADS)

    Shi, Zhanjie; Hobbs, Richard W.; Moorkamp, Max; Tian, Gang; Jiang, Lu

    2017-06-01

    We present a 3-D cross-gradient joint inversion algorithm for seismic refraction and DC resistivity data. The structural similarity between seismic slowness and resistivity models is enforced by a cross-gradient term in the objective function that also includes misfit and regularization terms. A limited memory quasi-Newton approach is used to perform the optimization of the objective function. To validate the proposed methodology and its implementation, tests were performed on a typical archaeological geophysical synthetic model. The results show that the inversion model and physical parameters estimated by our joint inversion method are more consistent with the true model than those from single inversion algorithm. Moreover, our approach appears to be more robust in conditions of noise. Finally, the 3-D cross-gradient joint inversion algorithm was applied to the field data from Lin_an ancient city site in Hangzhou of China. The 3-D cross-gradient joint inversion models are consistent with the archaeological excavation results of the ancient city wall remains. However, by single inversion, seismic slowness model does not show the anomaly of city wall remains and resistivity model does not fit well with the archaeological excavation results. Through these comparisons, we conclude that the proposed algorithm can be used to jointly invert 3-D seismic refraction and DC resistivity data to reduce the uncertainty brought by single inversion scheme.

  17. A framework for 3D joint inversion of MT, gravity and seismic refraction data (Invited)

    NASA Astrophysics Data System (ADS)

    Moorkamp, M.; Jegen, M. D.; Heincke, B.; Roberts, A. W.; Hobbs, R. W.

    2010-12-01

    We present a 3D joint inversion framework for seismic, magnetotelluric, along with scalar and tensorial gravity data. Using optimization methods suited for large-scale data sets, parallelization of the forward problems and a flexible implementation in terms of model parameterization allows us to investigate different coupling approaches for the various physical parameters involved in the joint inversion. Here we compare two different coupling schemes; direct parameter coupling, where we calculate conductivity and density from seismic slowness, and cross-gradient coupling where each model cell has an independent value for each physical property and structural similarity is enforced through an additional term in the objective function. In both approaches we see an improvement of the inversion results over single inversions when the inverted datasets are generated from compatible models. As expected, the direct coupling approach results in a stronger interaction between the datasets and in this case better results are obtained compared to the cross-gradient coupling. In contrast, when the inverted magnetotelluric data is generated from a model that violates the parameter relationship in some regions but conforms with the cross-gradient assumptions, we obtain good results with the cross-gradient approach, while the direct coupling approach results in spurious features. This makes the cross-gradient approach the first choice for regions where a direct relationship between the physical parameters is unclear.

  18. Identifying High Potential Well Targets with 3D Seismic and Mineralogy

    SciTech Connect

    Mellors, R. J.

    2015-10-30

    Seismic reflection the primary tool used in petroleum exploration and production, but use in geothermal exploration is less standard, in part due to cost but also due to the challenges in identifying the highly-permeable zones essential for economic hydrothermal systems [e.g. Louie et al., 2011; Majer, 2003]. Newer technology, such as wireless sensors and low-cost high performance computing, has helped reduce the cost and effort needed to conduct 3D surveys. The second difficulty, identifying permeable zones, has been less tractable so far. Here we report on the use of seismic attributes from a 3D seismic survey to identify and map permeable zones in a hydrothermal area.

  19. 3-D seismic tomographic modelling of the crustal structure of northwestern Svalbard based on deep seismic soundings

    NASA Astrophysics Data System (ADS)

    Czuba, Wojciech

    2016-11-01

    Wide angle refraction and reflection measurements were carried out in the passive continental margin zone of the northwestern Svalbard during several expeditions in 1978-1999. Data from a set of 2-D archival and modern seismic profiles recorded in-line and off-line, and from an additional permanent seismic station, were altogether used for seismic modelling of the crustal structure of the study area. Seismic arrivals (airgun and chemical explosive sources) were recorded by land (onshore) seismic stations, ocean bottom seismometers (OBS), and ocean bottom hydrophone stations (OBH). Good quality refracted and reflected P waves have provided an excellent data base for a seismic modelling. Chemical explosive sources were recorded even up to 300 km distances. The 3-D tomographic inversion method was applied. The results are comparable to the earlier 2-D modelling. Additional off-line information allowed to develop a 3-D image of the crustal structure. The continental crust thins to the west and north. A minimum depth of about 6 km to the Moho interface was determined east of the Molloy Deep and in the Knipovich Ridge. The Moho discontinuity deepens down to about 30 km below the continental crust of Spitsbergen.

  20. 3-D seismic tomographic modelling of the crustal structure of northwestern Svalbard based on deep seismic soundings

    NASA Astrophysics Data System (ADS)

    Czuba, Wojciech

    2017-01-01

    Wide angle refraction and reflection measurements were carried out in the passive continental margin zone of the northwestern Svalbard during several expeditions in 1978-1999. Data from a set of 2-D archival and modern seismic profiles recorded in-line and off-line, and from an additional permanent seismic station, were altogether used for seismic modelling of the crustal structure of the study area. Seismic arrivals (airgun and chemical explosive sources) were recorded by land (onshore) seismic stations, ocean bottom seismometers (OBS), and ocean bottom hydrophone stations (OBH). Good quality refracted and reflected P waves have provided an excellent data base for a seismic modelling. Chemical explosive sources were recorded even up to 300 km distances. The 3-D tomographic inversion method was applied. The results are comparable to the earlier 2-D modelling. Additional off-line information allowed to develop a 3-D image of the crustal structure. The continental crust thins to the west and north. A minimum depth of about 6 km to the Moho interface was determined east of the Molloy Deep and in the Knipovich Ridge. The Moho discontinuity deepens down to about 30 km below the continental crust of Spitsbergen.

  1. An optimal transport approach for seismic tomography: application to 3D full waveform inversion

    NASA Astrophysics Data System (ADS)

    Métivier, L.; Brossier, R.; Mérigot, Q.; Oudet, E.; Virieux, J.

    2016-11-01

    The use of optimal transport distance has recently yielded significant progress in image processing for pattern recognition, shape identification, and histograms matching. In this study, the use of this distance is investigated for a seismic tomography problem exploiting the complete waveform; the full waveform inversion. In its conventional formulation, this high resolution seismic imaging method is based on the minimization of the L 2 distance between predicted and observed data. Application of this method is generally hampered by the local minima of the associated L 2 misfit function, which correspond to velocity models matching the data up to one or several phase shifts. Conversely, the optimal transport distance appears as a more suitable tool to compare the misfit between oscillatory signals, for its ability to detect shifted patterns. However, its application to the full waveform inversion is not straightforward, as the mass conservation between the compared data cannot be guaranteed, a crucial assumption for optimal transport. In this study, the use of a distance based on the Kantorovich-Rubinstein norm is introduced to overcome this difficulty. Its mathematical link with the optimal transport distance is made clear. An efficient numerical strategy for its computation, based on a proximal splitting technique, is introduced. We demonstrate that each iteration of the corresponding algorithm requires solving the Poisson equation, for which fast solvers can be used, relying either on the fast Fourier transform or on multigrid techniques. The development of this numerical method make possible applications to industrial scale data, involving tenths of millions of discrete unknowns. The results we obtain on such large scale synthetic data illustrate the potentialities of the optimal transport for seismic imaging. Starting from crude initial velocity models, optimal transport based inversion yields significantly better velocity reconstructions than those based on

  2. Advancing New 3D Seismic Interpretation Methods for Exploration and Development of Fractured Tight Gas Reservoirs

    SciTech Connect

    James Reeves

    2005-01-31

    In a study funded by the U.S. Department of Energy and GeoSpectrum, Inc., new P-wave 3D seismic interpretation methods to characterize fractured gas reservoirs are developed. A data driven exploratory approach is used to determine empirical relationships for reservoir properties. Fractures are predicted using seismic lineament mapping through a series of horizon and time slices in the reservoir zone. A seismic lineament is a linear feature seen in a slice through the seismic volume that has negligible vertical offset. We interpret that in regions of high seismic lineament density there is a greater likelihood of fractured reservoir. Seismic AVO attributes are developed to map brittle reservoir rock (low clay) and gas content. Brittle rocks are interpreted to be more fractured when seismic lineaments are present. The most important attribute developed in this study is the gas sensitive phase gradient (a new AVO attribute), as reservoir fractures may provide a plumbing system for both water and gas. Success is obtained when economic gas and oil discoveries are found. In a gas field previously plagued with poor drilling results, four new wells were spotted using the new methodology and recently drilled. The wells have estimated best of 12-months production indicators of 2106, 1652, 941, and 227 MCFGPD. The latter well was drilled in a region of swarming seismic lineaments but has poor gas sensitive phase gradient (AVO) and clay volume attributes. GeoSpectrum advised the unit operators that this location did not appear to have significant Lower Dakota gas before the well was drilled. The other three wells are considered good wells in this part of the basin and among the best wells in the area. These new drilling results have nearly doubled the gas production and the value of the field. The interpretation method is ready for commercialization and gas exploration and development. The new technology is adaptable to conventional lower cost 3D seismic surveys.

  3. Integrating 3D seismic curvature and curvature gradient attributes for fracture characterization: Methodologies and interpretational implications

    SciTech Connect

    Gao, Dengliang

    2013-03-01

    In 3D seismic interpretation, curvature is a popular attribute that depicts the geometry of seismic reflectors and has been widely used to detect faults in the subsurface; however, it provides only part of the solutions to subsurface structure analysis. This study extends the curvature algorithm to a new curvature gradient algorithm, and integrates both algorithms for fracture detection using a 3D seismic test data set over Teapot Dome (Wyoming). In fractured reservoirs at Teapot Dome known to be formed by tectonic folding and faulting, curvature helps define the crestal portion of the reservoirs that is associated with strong seismic amplitude and high oil productivity. In contrast, curvature gradient helps better define the regional northwest-trending and the cross-regional northeast-trending lineaments that are associated with weak seismic amplitude and low oil productivity. In concert with previous reports from image logs, cores, and outcrops, the current study based on an integrated seismic curvature and curvature gradient analysis suggests that curvature might help define areas of enhanced potential to form tensile fractures, whereas curvature gradient might help define zones of enhanced potential to develop shear fractures. In certain fractured reservoirs such as at Teapot Dome where faulting and fault-related folding contribute dominantly to the formation and evolution of fractures, curvature and curvature gradient attributes can be potentially applied to differentiate fracture mode, to predict fracture intensity and orientation, to detect fracture volume and connectivity, and to model fracture networks.

  4. On horizontal resolution for seismic acquisition geometries in complex 3D media

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Fu, Li-Yun

    2014-09-01

    Spatial sampling has a crucial influence on the horizontal resolution of seismic imaging, but how to quantify the influence is still controversial especially in complex media. Most of the studies on horizontal resolution focus on the measurement of wavelet widths for seismic migration, but neglect to evaluate the effect of side-lobe perturbations on spatial resolution. The side-lobe effect, as a migration noise, is important for seismic imaging in complex media. In this article, with focal beam analysis, we define two parameters to represent the horizontal resolution of an acquisition geometry: the width of the main lobe (WML) along the inline and crossline directions and the ratio of the main-lobe amplitude to the total amplitude (RMT) in a focal beam. We provide examples of typical acquisition geometries to show how spatial sampling affects the horizontal resolution, measured in terms of WML and RMT values. WML defines the horizontal resolution to image the target, whereas RMT describes the clarity of the imaging. Migration noise reduces with increasing RMT, indirectly improving both the vertical and horizontal resolutions of seismic imaging. Case studies of seismic migration with 3D seismic data from an oil field of China, demonstrate how the acquisition geometries with different WML and RMT values influence the performance of seismic imaging. Prior WML and RMT analyses to predict the quality of acquired datasets can optimize acquisition geometries before the implementation of seismic acquisition.

  5. Reservoir lithofacies analysis using 3D seismic data in dissimilarity space

    NASA Astrophysics Data System (ADS)

    Bagheri, M.; Riahi, M. A.; Hashemi, H.

    2013-06-01

    Seismic data interpretation is one of the most important steps in exploration seismology. Seismic facies analysis (SFA) with emphasis on lithofacies can be used to extract more information about structures and geology, which results in seismic interpretation enhancement. Facies analysis is based on unsupervised and supervised classification using seismic attributes. In this paper, supervised classification by a support vector machine using well logs and seismic attributes is applied. Dissimilarity as a new measuring space is employed, after which classification is carried out. Often, SFA is carried out in a feature space in which each dimension stands as a seismic attribute. Different facies show lots of class overlap in the feature space; hence, high classification error values are reported. Therefore, decreasing class overlap before classification is a necessary step to be targeted. To achieve this goal, a dissimilarity space is initially created. As a result of the definition of the new space, the class overlap between objects (seismic samples) is reduced and hence the classification can be done reliably. This strategy causes an increase in the accuracy of classification, and a more trustworthy lithofacies analysis is attained. For applying this method, 3D seismic data from an oil field in Iran were selected and the results obtained by a support vector classifier (SVC) in dissimilarity space are presented, discussed and compared with the SVC applied in conventional feature space.

  6. A 3D Numerical Survey of Seismic Waves Inside and Around an Underground Cavity

    NASA Astrophysics Data System (ADS)

    Esterhazy, S.; Schneider, F. M.; Perugia, I.; Bokelmann, G.

    2016-12-01

    Motivated by the need to detect an underground cavity within the procedure of an On-Site-Inspection (OSI) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), which might be caused by a nuclear explo- sion/weapon testing, we present our findings of a numerical study on the elastic wave propagation inside and around such an underground cavity.The aim of the CTBTO is to ban all nuclear explosions of any size anywhere, by anyone. Therefore, it is essential to build a powerful strategy to efficiently investigate and detect critical signatures such as gas filled cavities, rubble zones and fracture networks below the surface. One method to investigate the geophysical properties of an under- ground cavity allowed by the Comprehensive Nuclear-test Ban Treaty is referred to as "resonance seismometry" - a resonance method that uses passive or active seismic techniques, relying on seismic cavity vibrations. This method is in fact not yet entirely determined by the Treaty and there are also only few experimental examples that have been suitably documented to build a proper scientific groundwork. This motivates to investigate this problem on a purely numerical level and to simulate these events based on recent advances in the mathematical understanding of the underlying physical phenomena.Our numerical study includes the full elastic wave field in three dimensions. We consider the effects from an in- coming plane wave as well as point source located in the surrounding of the cavity at the surface. While the former can be considered as passive source like a tele-seismic earthquake, the latter represents a man-made explosion or a viborseis as used for/in active seismic techniques. For our simulations in 3D we use the discontinuous Galerkin Spectral Element Code SPEED developed by MOX (The Laboratory for Modeling and Scientific Computing, Department of Mathematics) and DICA (Department of Civil and Environmental Engineering) at the Politecnico di Milano. The

  7. Validation of 3D Seismic Velocity Models Using the Spectral Element Method

    NASA Astrophysics Data System (ADS)

    Maceira, M.; Larmat, C. S.; Porritt, R. W.; Higdon, D.; Allen, R. M.

    2012-12-01

    For over a decade now, many research institutions have been focusing on addressing the Earth's 3D heterogeneities and complexities by improving tomographic methods. Utilizing dense array datasets, these efforts have led to unprecedented 3D seismic images, but little is done in terms of model validation or to provide any absolute assessment of model uncertainty. Furthermore, the question of "How good is a 3D geophysical model at representing the Earth's true physics? " remains largely not addressed in a time when 3D Earth models are used for societal and energy security. In the last few years, new horizons have opened up in earth structure imaging, with the advent of new numerical and mathematical methods in computational seismology and statistical sciences. We use these methods to tackle the question of model validation taking advantage of unique and extensive High Performance Computing resources available at Los Alamos National Laboratory. We present results from a study focused on validating 3D models for the Western USA generated using both ray-theoretical and finite-frequency approximations. In this manner we do not validate just the model but also the imaging technique. For this test case, we utilize the Dynamic North America (DNA) model family of UC Berkeley, as they are readily available in both formulations. We evaluate model performances by comparing observed and synthetic seismograms generated using the Spectral Element Method. Results show that both, finite-frequency and ray-theoretical DNA09 models, predict the observations well. Waveform cross-correlation coefficients show a difference in performance between models obtained with the finite-frequency or ray-theory limited to smallest periods (<15s), with no perceptible difference at longer periods (50-200s). At those shortest periods, and based on statistical analyses on S-wave phase delay measurements, finite-frequency shows an improvement over ray theory. We are also investigating the breakdown of ray

  8. 3D and 4D Seismic Imaging in the Oilfield; the state of the art

    NASA Astrophysics Data System (ADS)

    Strudley, A.

    2005-05-01

    Seismic imaging in the oilfield context has seen enormous changes over the last 20 years driven by a combination of improved subsurface illumination (2D to 3D), increased computational power and improved physical understanding. Today Kirchhoff Pre-stack migration (in time or depth) is the norm with anisotropic parameterisation and finite difference methods being increasingly employed. In the production context Time-Lapse (4D) Seismic is of growing importance as a tool for monitoring reservoir changes to facilitate increased productivity and recovery. In this paper we present an overview of state of the art technology in 3D and 4D seismic and look at future trends. Pre-stack Kirchhoff migration in time or depth is the imaging tool of choice for the majority of contemporary 3D datasets. Recent developments in 3D pre-stack imaging have been focussed around finite difference solutions to the acoustic wave equation, the so-called Wave Equation Migration methods (WEM). Application of finite difference solutions to imaging is certainly not new, however 3D pre-stack migration using these schemes is a relatively recent development driven by the need for imaging complex geologic structures such as sub salt, and facilitated by increased computational resources. Finally there are a class of imaging methods referred to as beam migration. These methods may be based on either the wave equation or rays, but all operate on a localised (in space and direction) part of the wavefield. These methods offer a bridge between the computational efficiency of Kirchhoff schemes and the improved image quality of WEM methods. Just as 3D seismic has had a radical impact on the quality of the static model of the reservoir, 4D seismic is having a dramatic impact on the dynamic model. Repeat shooting of seismic surveys after a period of production (typically one to several years) reveals changes in pressure and saturation through changes in the seismic response. The growth in interest in 4D seismic

  9. Prestack reverse time migration for 3D marine reflection seismic data

    SciTech Connect

    Jang, Seonghyung; Kim, Taeyoun

    2015-03-10

    Prestack reverse time migration (RTM) is a method for imaging the subsurface using the inner product of wavefield extrapolation in shot domain and in receiver domain. It is well known that RTM is better for preserving amplitudes and phases than other prestack migrations. Since 3D seismic data is huge data volume and it needs heavy computing works, it requires parallel computing in order to have a meaningful depth image of the 3D subsurface. We implemented a parallelized version of 3D RTM for prestack depth migration. The results of numerical example for 3D SEG/EAGE salt model showed good agreement with the original geological model. We applied RTM to offshore 3D seismic reflection data. The study area is 12 × 25 km with 120 survey lines. Shot and receiver spacing is 25 m and 12.5 m. The line spacing is 100 m. Shot gathers were preprocessed to enhance signal to noise ratio and velocity model was calculated from conventional stack velocity. Both of them were used to obtain 3D image using RTM. The results show reasonable subsurface image.

  10. P-Cable: New High-Resolution 3D Seismic Acquisition Technology

    NASA Astrophysics Data System (ADS)

    Planke, Sverre; Berndt, Christian; Mienert, Jürgen; Bünz, Stefan; Eriksen, Frode N.; Eriksen, Ola K.

    2010-05-01

    We have developed a new cost-efficient technology for acquisition of high-resolution 3D seismic data: the P-Cable system. This technology is very well suited for deep water exploration, site surveys, and studies of shallow gas and fluid migration associated with gas hydrates or leaking reservoirs. It delivers unparalleled 3D seismic images of subsurface sediment architectures. The P-Cable system consists of a seismic cable towed perpendicular to a vessel's steaming direction. This configuration allows us to image an up to 150 m wide swath of the sub-surface for each sail line. Conventional 3D seismic technology relies on several very long streamers (up to 10 km long streamers are common), large sources, and costly operations. In contrast, the P-Cable system is light-weight and fast to deploy from small vessels. Only a small source is required as the system is made for relatively shallow imaging, typically above the first water-bottom multiple. The P-Cable system is particularly useful for acquisition of small 3D cubes, 10-50 km2, in focus areas, rather than extensive mapping of large regions. The rapid deployment and recovery of the system makes it possible to acquire several small cubes (10 to 30 km2) with high-resolution (50-250 Hz) seismic data in during one cruise. The first development of the P-Cable system was a cooperative project achieved by Volcanic Basin Petroleum Research (VBPR), University of Tromsø, National Oceanography Centre, Southampton, and industry partners. Field trials using a 12-streamer system were conducted on sites with active fluid-leakage systems on the Norwegian-Barents-Svalbard margin, the Gulf of Cadiz, and the Mediterranean. The second phase of the development introduced digital streamers. The new P-Cable2 system also includes integrated tow and cross cables for power and data transmission and improved doors to spread the larger cross cable. This digital system has been successfully used during six cruises by the University of Troms

  11. Full Waveform 3D Synthetic Seismic Algorithm for 1D Layered Anelastic Models

    NASA Astrophysics Data System (ADS)

    Schwaiger, H. F.; Aldridge, D. F.; Haney, M. M.

    2007-12-01

    Numerical calculation of synthetic seismograms for 1D layered earth models remains a significant aspect of amplitude-offset investigations, surface wave studies, microseismic event location approaches, and reflection interpretation or inversion processes. Compared to 3D finite-difference algorithms, memory demand and execution time are greatly reduced, enabling rapid generation of seismic data within workstation or laptop computational environments. We have developed a frequency-wavenumber forward modeling algorithm adapted to realistic 1D geologic media, for the purpose of calculating seismograms accurately and efficiently. The earth model consists of N layers bounded by two halfspaces. Each layer/halfspace is a homogeneous and isotropic anelastic (attenuative and dispersive) solid, characterized by a rectangular relaxation spectrum of absorption mechanisms. Compressional and shear phase speeds and quality factors are specified at a particular reference frequency. Solution methodology involves 3D Fourier transforming the three coupled, second- order, integro-differential equations for particle displacements to the frequency-horizontal wavenumber domain. An analytic solution of the resulting ordinary differential system is obtained. Imposition of welded interface conditions (continuity of displacement and stress) at all interfaces, as well as radiation conditions in the two halfspaces, yields a system of 6(N+1) linear algebraic equations for the coefficients in the ODE solution. An optimized inverse 2D Fourier transform to the space domain gives the seismic wavefield on a horizontal plane. Finally, three-component seismograms are obtained by accumulating frequency spectra at designated receiver positions on this plane, followed by a 1D inverse FFT from angular frequency ω to time. Stress-free conditions may be applied at the top or bottom interfaces, and seismic waves are initiated by force or moment density sources. Examples reveal that including attenuation

  12. Coupling the 3D hydro-morphodynamic model Telemac-3D-sisyphe and seismic measurements to estimate bedload transport rates in a small gravel-bed river.

    NASA Astrophysics Data System (ADS)

    Hostache, Renaud; Krein, Andreas; Barrière, Julien

    2014-05-01

    Coupling the 3D hydro-morphodynamic model Telemac-3D-sisyphe and seismic measurements to estimate bedload transport rates in a small gravel-bed river. Renaud Hostache, Andreas Krein, Julien Barrière During flood events, amounts of river bed material are transported via bedload. This causes problems, like the silting of reservoirs or the disturbance of biological habitats. Some current bedload measuring techniques have limited possibilities for studies in high temporal resolutions. Optical systems are usually not applicable because of high turbidity due to concentrated suspended sediment transported. Sediment traps or bedload samplers yield only summative information on bedload transport with low temporal resolution. An alternative bedload measuring technique is the use of seismological systems installed next to the rivers. The potential advantages are observations in real time and under undisturbed conditions. The study area is a 120 m long reach of River Colpach (21.5 km2), a small gravel bed river in Northern Luxembourg. A combined approach of hydro-climatological observations, hydraulic measurements, sediment sampling, and seismological measurements is used in order to investigate bedload transport phenomena. Information derived from seismic measurements and results from a 3-dimensional hydro-morphodynamic model are exemplarily discussed for a November 2013 flood event. The 3-dimensional hydro-morphodynamic model is based on the Telemac hydroinformatic system. This allows for dynamically coupling a 3D hydrodynamic model (Telemac-3D) and a morphodynamic model (Sisyphe). The coupling is dynamic as these models exchange their information during simulations. This is a main advantage as it allows for taking into account the effects of the morphologic changes of the riverbed on the water hydrodynamic and the bedload processes. The coupled model has been calibrated using time series of gauged water depths and time series of bed material collected sequentially (after

  13. ActiveSeismoPick3D - automatic first arrival determination for large active seismic arrays

    NASA Astrophysics Data System (ADS)

    Paffrath, Marcel; Küperkoch, Ludger; Wehling-Benatelli, Sebastian; Friederich, Wolfgang

    2016-04-01

    We developed a tool for automatic determination of first arrivals in active seismic data based on an approach, that utilises higher order statistics (HOS) and the Akaike information criterion (AIC), commonly used in seismology, but not in active seismics. Automatic picking is highly desirable in active seismics as the number of data provided by large seismic arrays rapidly exceeds of what an analyst can evaluate in a reasonable amount of time. To bring the functionality of automatic phase picking into the context of active data, the software package ActiveSeismoPick3D was developed in Python. It uses a modified algorithm for the determination of first arrivals which searches for the HOS maximum in unfiltered data. Additionally, it offers tools for manual quality control and postprocessing, e.g. various visualisation and repicking functionalities. For flexibility, the tool also includes methods for the preparation of geometry information of large seismic arrays and improved interfaces to the Fast Marching Tomography Package (FMTOMO), which can be used for the prediction of travel times and inversion for subsurface properties. Output files are generated in the VTK format, allowing the 3D visualization of e.g. the inversion results. As a test case, a data set consisting of 9216 traces from 64 shots was gathered, recorded at 144 receivers deployed in a regular 2D array of a size of 100 x 100 m. ActiveSeismoPick3D automatically checks the determined first arrivals by a dynamic signal to noise ratio threshold. From the data a 3D model of the subsurface was generated using the export functionality of the package and FMTOMO.

  14. How 3D seismic-CAEX combination affected development of N. Frisco City field in Alabama

    SciTech Connect

    Stephenson, M.; Cox, J.; Jones-Fuentes, P. )

    1992-10-26

    This paper reports that by applying the latest in 3D seismic and computer aided exploration and production (CAEX) technology, small and mid-size independents are changing the methods by which fields are discovered and profitably developed. The combination of 3D and CAEX has, in many cases, altered oilfield economics. Nuevo Energy Co.'s North Frisco City development---located in the updip Jurassic Haynesville trend of Southwest Alabama---offers a case in point. The 3D technology employed at North Frisco City produced and accurate, detailed picture of the subsurface. Ultimately it more than doubled the drilling success rate over that of a nearby, closely related field in which 3D was not used.

  15. 3D Porosity Estimation of the Nankai Trough Sediments from Core-log-seismic Integration

    NASA Astrophysics Data System (ADS)

    Park, J. O.

    2015-12-01

    The Nankai Trough off southwest Japan is one of the best subduction-zone to study megathrust earthquake fault. Historic, great megathrust earthquakes with a recurrence interval of 100-200 yr have generated strong motion and large tsunamis along the Nankai Trough subduction zone. At the Nankai Trough margin, the Philippine Sea Plate (PSP) is being subducted beneath the Eurasian Plate to the northwest at a convergence rate ~4 cm/yr. The Shikoku Basin, the northern part of the PSP, is estimated to have opened between 25 and 15 Ma by backarc spreading of the Izu-Bonin arc. The >100-km-wide Nankai accretionary wedge, which has developed landward of the trench since the Miocene, mainly consists of offscraped and underplated materials from the trough-fill turbidites and the Shikoku Basin hemipelagic sediments. Particularly, physical properties of the incoming hemipelagic sediments may be critical for seismogenic behavior of the megathrust fault. We have carried out core-log-seismic integration (CLSI) to estimate 3D acoustic impedance and porosity for the incoming sediments in the Nankai Trough. For the CLSI, we used 3D seismic reflection data, P-wave velocity and density data obtained during IODP (Integrated Ocean Drilling Program) Expeditions 322 and 333. We computed acoustic impedance depth profiles for the IODP drilling sites from P-wave velocity and density data. We constructed seismic convolution models with the acoustic impedance profiles and a source wavelet which is extracted from the seismic data, adjusting the seismic models to observed seismic traces with inversion method. As a result, we obtained 3D acoustic impedance volume and then converted it to 3D porosity volume. In general, the 3D porosities show decrease with depth. We found a porosity anomaly zone with alteration of high and low porosities seaward of the trough axis. In this talk, we will show detailed 3D porosity of the incoming sediments, and present implications of the porosity anomaly zone for the

  16. Complex Crustal Structure Beneath Western Turkey Revealed by 3D Seismic Full Waveform Inversion (FWI)

    NASA Astrophysics Data System (ADS)

    Cubuk-Sabuncu, Yesim; Taymaz, Tuncay; Fichtner, Andreas

    2016-04-01

    We present a 3D radially anisotropic velocity model of the crust and uppermost mantle structure beneath the Sea of Marmara and surroundings based on the full waveform inversion method. The intense seismic activity and crustal deformation are observed in the Northwest Turkey due to transition tectonics between the strike-slip North Anatolian Fault (NAF) and the extensional Aegean region. We have selected and simulated complete waveforms of 62 earthquakes (Mw > 4.0) occurred during 2007-2015, and recorded at (Δ < 10°) distances. Three component earthquake data is obtained from broadband seismic stations of Kandilli Observatory and Earthquake Research Center (KOERI, Turkey), Hellenic Unified Seismic Network (HUSN, Greece) and Earthquake Research Center of Turkey (AFAD-DAD). The spectral-element solver of the wave equation, SES3D algorithm, is used to simulate seismic wave propagation in 3D spherical coordinates (Fichtner, 2009). The Large Scale Seismic Inversion Framework (LASIF) workflow tool is also used to perform full seismic waveform inversion (Krischer et al., 2015). The initial 3D Earth model is implemented from the multi-scale seismic tomography study of Fichtner et al. (2013). Discrepancies between the observed and simulated synthetic waveforms are determined using the time-frequency misfits which allows a separation between phase and amplitude information (Fichtner et al., 2008). The conjugate gradient optimization method is used to iteratively update the initial Earth model when minimizing the misfit. The inversion is terminated after 19 iterations since no further advances are observed in updated models. Our analysis revealed shear wave velocity variations of the shallow and deeper crustal structure beneath western Turkey down to depths of ~35-40 km. Low shear wave velocity anomalies are observed in the upper and mid crustal depths beneath major fault zones located in the study region. Low velocity zones also tend to mark the outline of young volcanic

  17. Characterization of a landslide geometry using 3D seismic refraction traveltime tomography: The La Valette landslide case history

    NASA Astrophysics Data System (ADS)

    Samyn, K.; Travelletti, J.; Bitri, A.; Grandjean, G.; Malet, J.-P.

    2012-11-01

    The geometry of the bedrock, internal layers and shear surfaces/bands controls the deformation pattern and the mechanisms of landslides. A challenge to progress in the forecast of landslide acceleration in terms of early-warning is therefore to characterize the 3D geometry of the unstable mass at a high level of spatial resolution, both in the horizontal and vertical directions, by integrating information from different surveying techniques. For such characterization, seismic investigations are potentially of a great interest. In the case of complex structures, the measure and the processing of seismic data need to be performed in 3D. The objective of this work is to present the development of a 3D extension of a seismic refraction traveltime tomography technique based on a Simultaneous Iterative Reconstruction Technique (SIRT). First the processing algorithm is detailed and its performance is discussed, and second an application to the La Valette complex landslide is presented. Inversion of first-arrival traveltimes produces a 3D tomogram that underlines the presence of many areas characterized by low P-wave velocity of 500-1800 m.s- 1. These low P-wave velocity structures result from the presence of reworked blocks, surficial cracks and in-depth fracture zones. These structures seem to extend to around 25 m in depth over a 80 × 130 m area. Based on borehole geotechnical data and previous geophysical investigations, an interface corresponding to an internal slip surface can be suspected near the isovalue of 1200 m.s- 1 at a depth of - 10 to - 15 m. The stable substratum is characterized by higher values of P-wave velocity of 1800-3000 m.s- 1. The features identified in the 3D tomogram allow to better (1) delineate the boundary between the landslide and the surrounding stable slopes, and (2) understand the morphological structures within the landslide at a hectometric scale. The integration of the 3D seismic tomography interpretation to previous geophysical

  18. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    SciTech Connect

    Lestari, Titik; Nugraha, Andri Dian

    2015-04-24

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

  19. Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

    NASA Astrophysics Data System (ADS)

    Lestari, Titik; Nugraha, Andri Dian

    2015-04-01

    Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA's) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 - April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

  20. Stratigraphic Interpretation and Reservoir Implications of the Arbuckle Group (Cambrian-Ordovician) using 3D Seismic, Osage County, Oklahoma

    NASA Astrophysics Data System (ADS)

    Keeling, Ryan Marc

    The Arbuckle Group in northeastern Oklahoma consists of multiple carbonate formations, along with several relatively thin sandstone units. The group is a part of the "Great American Carbonate Bank" of the mid-continent and can be found regionally as far east as the Arkoma Basin in Arkansas, and as far west as the Anadarko Basin in Oklahoma. The Arbuckle is part of the craton-wide Sauk sequence, which is both underlain and overlain by regional unconformities. Arbuckle is not deposited directly on top of a source rock. In order for reservoirs within the Arbuckle to become charged with hydrocarbons, they must be juxtaposed against source rocks or along migration pathways. Inspired by the petroleum potential of proximal Arbuckle reservoirs and the lack of local stratigraphic understanding, this study aims to subdivide Arbuckle stratigraphy and identify porosity networks using 3D seismic within the study area of western Osage County, Oklahoma. These methods and findings can then be applied to petroleum exploration in Cambro-Ordovician carbonates in other localities. My research question is: Can the Arbuckle in SW Osage County be stratigraphically subdivided based on 3D seismic characteristics? This paper outlines the depositional environment of the Arbuckle, synthesizes previous studies and examines the Arbuckle as a petroleum system in Northeastern Oklahoma. The investigation includes an interpretation of intra-Arbuckle unconformities, areas of secondary porosity (specifically, sequence boundaries), and hydrocarbon potential of the Arbuckle Group using 3D seismic data interpretation with a cursory analysis of cored intervals.

  1. Geological model of Lobodice underground gas storage facility based on 3D seismic interpretation

    NASA Astrophysics Data System (ADS)

    Kopal, Lukáš; Čížek, Pavel; Milička, Ján

    2016-06-01

    The Lobodice underground gas storage (UGS) is developed in a natural aquifer reservoir located in the Central Moravian part of the Carpathian Foredeep in the Czech Republic. In order to learn more about the UGS geological structure a 3D seismic survey was performed in 2009. The reservoir is rather shallow, 400-500 m below the surface. This article describes the process workflow from the 3D seismic field data acquisition to the creation of the geological model. The outcomes of this workflow define the geometry of the UGS reservoir, its tectonics and the sealing features of the structure. Better geological knowledge of the reservoir will reduce the risks involved in the localization of new wells for increasing UGS withdrawal rates.

  2. Combining sequence stratigraphy with 3-D seismic imaging in low-accommodation basins

    SciTech Connect

    Hardage, B.A.; Carr, D.L.; Simmons, J.L. Jr.

    1995-12-31

    Pennsylvania-age rocks in several areas of the Midcontinent of the United States were deposited in low-accommodation basinal settings, that is, in basinal areas where only modest verticle reliefs could accept the sediment influx. Many thin Pennsylvanian sequences in these low-accommodation environments exhibit severe lateral heterogeneity because they have been extensively reworked by repeated transgressions and regressions of a fluctuating sea. Consequently, the distinctive geometries of relic depositional features (such as meandering channels) tend to be distorted or even totally destroyed, as compared with how such geometries appear in high-accommodation basins where depositional topography, once buried, is rarely exposed to destructive processes. Our objectives are to show examples of 3-D seismic images of several depositional topographies in a moderate- to low-accommodation basin and to explain how these thin sequences can be identified in well control and interpreted in 3-D seismic data volumes.

  3. 3-D seismic case history of the dawn 156 pinnacle reef

    SciTech Connect

    Egden, J.G.; Horan, M.T. ); Nader, S.M. )

    1994-08-01

    Silurian pinnacle reefs are used for gas storage in southern Ontario and southeast Michigan. These reefs underlie surface culture that is frequently incompatible with enhanced reservoir exploitation techniques such as 3-D seismic. Further complications are encountered due to an increased awareness of environmental concerns and past exploration or local production practices. Employing proactive project management in a team-oriented environment, Union Gas Ltd., successfully conducted a 2732 ac 3-D seismic survey in 1993-1994. The project brought together a multidisciplinary team that included company employees, consultants, service companies, and surface landowners. This case history covers the project from conceptualization through the team-building processes and final selection of additional drilling locations. The project management philosophy employed has potential application in the upstream sector.

  4. Multi-hole seismic modeling in 3-D space and cross-hole seismic tomography analysis for boulder detection

    NASA Astrophysics Data System (ADS)

    Cheng, Fei; Liu, Jiangping; Wang, Jing; Zong, Yuquan; Yu, Mingyu

    2016-11-01

    A boulder stone, a common geological feature in south China, is referred to the remnant of a granite body which has been unevenly weathered. Undetected boulders could adversely impact the schedule and safety of subway construction when using tunnel boring machine (TBM) method. Therefore, boulder detection has always been a key issue demanded to be solved before the construction. Nowadays, cross-hole seismic tomography is a high resolution technique capable of boulder detection, however, the method can only solve for velocity in a 2-D slice between two wells, and the size and central position of the boulder are generally difficult to be accurately obtained. In this paper, the authors conduct a multi-hole wave field simulation and characteristic analysis of a boulder model based on the 3-D elastic wave staggered-grid finite difference theory, and also a 2-D imaging analysis based on first arrival travel time. The results indicate that (1) full wave field records could be obtained from multi-hole seismic wave simulations. Simulation results describe that the seismic wave propagation pattern in cross-hole high-velocity spherical geological bodies is more detailed and can serve as a basis for the wave field analysis. (2) When a cross-hole seismic section cuts through the boulder, the proposed method provides satisfactory cross-hole tomography results; however, when the section is closely positioned to the boulder, such high-velocity object in the 3-D space would impact on the surrounding wave field. The received diffracted wave interferes with the primary wave and in consequence the picked first arrival travel time is not derived from the profile, which results in a false appearance of high-velocity geology features. Finally, the results of 2-D analysis in 3-D modeling space are comparatively analyzed with the physical model test vis-a-vis the effect of high velocity body on the seismic tomographic measurements.

  5. 2D/3D velocity model for the high resolution 2D and 3D seismic data from the CO2SINK Ketzin Project

    NASA Astrophysics Data System (ADS)

    Ivanova, A.; Asch, G.; Lueth, S.; Goetz, J.

    2009-04-01

    Seismic traveltime inversion, traveltime tomography and seismic reflection techniques have been applied for two dimensional (2D) and three dimensional (3D) data acquired in conjunction with characterization and monitoring aspects at a carbon dioxide (CO2) geological storage site at Ketzin, Germany (the CO2SINK project) (S.Yordkayhun, 2008). A seismic source comparison from the 2D pilot study regarding acquisition parameters have been tested at the side has shown the weight drop source is suitable concerning the signal penetration, frequency content of the data and minimizing time and costs for the 3D data acquisition. For the Ketzin seismic data, the ability to obtain an accurate 2D/3D interval velocity model is limited by the acquisition geometry, source-generated noise and time shifts due to the near-surface effects producing severe distortions in the data. Moreover, these time shifts are comparable to the dominant periods of the reflections and to the size of structures to be imaged. Therefore, a combination of seismic refraction and state-of-the-art processing techniques, including careful static corrections and more accurate velocity analysis, has resulted in key improvements of the images and has allowed new information about the 2D/3D interval velocities. The results from these studies together with borehole information, hydrogeologic models and seismic modeling will be combined into an integrated 2D/3D velocity model. After that a careful 2D/3D depth migration is to be provided. It can be used as a database for the future monitoring program at the site.

  6. 3-D seismic facies analysis of a reefal buildup, offshore North Sumatra

    SciTech Connect

    Alexander, W.L.; Nellia, M.R. )

    1994-07-01

    The [open quotes]A[close quotes] field is located on the Sunda shelf, offshore north Sumatra. The A-1 discovery well, drilled in 1972, found hydrocarbon gas in middle Miocene carbonate rocks of reefal origin. Six appraisal wells were subsequently drilled, the most recent in late 1990. Because of drilling problems, mainly lost circulation in the carbonate reservoir, the well data obtained from the appraisal program was generally disappointing. Prior to development of the offshore area, an extensive 3-D seismic survey was shot, a portion of which covered the [open quotes]A[close quotes] field. Interpretation of the 3-D data over the [open quotes]A[close quotes] field identified different seismic facies within the carbonate reservoir. These seismic facies have been integrated with the geological data in order to construct a depositional model for the field. The seismic facies analysis was critical for developing the model because of the inadequate geological data obtained from the wells. Three distinct facies could be identified on the 3-D seismic data and correlated with the well data: reef, near-reef and inter-reef. The main concerns this facies mapping addressed were reserve determination, areas of severe lost circulation, and the distribution of dolomite. The near-reef and inter-reef areas were found to have better reservoir properties than the reef core, thereby impacting reserve calculations. In addition, the reef facies, with zones of vuggy to near cavernous type porosity, was correlatable to wells that had experienced severe lost circulation. Finally, dolomite was found to occur only within the reef facies, enabling its distribution to be predicted.

  7. 3D Geotechnical Soil Model of Nice, France, Inferred from Seismic Noise Measurements, for Seismic Hazard Assessment.

    NASA Astrophysics Data System (ADS)

    Bertrand, E.; Duval, A.; Castan, M.; Vidal, S.

    2007-12-01

    In seismic risk studies, the assessment of lithologic site effect is based on an accurate knowledge of mechanical properties and geometry of superficial geological formations. Therefore, we built a 3D subsurface model in the city of Nice, southeastern France, using not only geological and geotechnical data but also geophysical inputs. We used especially ambient vibration recordings to supply the lack of borehole data over the city. Nice spreads over 72 km2 and roughly 20% of the city is built upon recent alluvium deposits. Other parts of the city lie on Jurassic and Cretaceous rocks to the east and thick Pliocene conglomerates to the west. Nearly 450 boreholes located mainly in the alluvial valleys were used. Because they are essentially linked to previous planned constructions (such as road network or important building), their distribution is rather heterogeneous over the studied area. In the valleys moreover, less than 40% of the boreholes are reaching the rock basement. These boreholes have been analyzed and a representative soil column made of 9 sedimentary layers has been recognized. Shear wave velocity of these layers were obtained from Standard Penetration Test values using several empirical correlation law described in the literature. Because of its cost, an extended boring survey was not feasible to complete our data set. Traditional seismic profiling was also not intended, as it is not possible to use intensive explosive sources in town. Recent years have seen many studies using ambient vibration measurements for site effect estimation. Especially, the very simple H/V technique was proven to be suitable for microzoning studies although some limitation were pointed out when dealing with 2D or 3D structures. Nevertheless, this technique alone provides only the fundamental eigenfrequency of the site under investigation. But assuming the shear wave velocity in the sediment it can helps to constrain the depth of the bedrock thanks to the well known f0=VS/4H

  8. 3-D Characterization of Seismic Properties at the Smart Weapons Test Range, YPG

    NASA Astrophysics Data System (ADS)

    Miller, Richard D.; Anderson, Thomas S.; Davis, John C.; Steeples, Don W.; Moran, Mark L.

    2001-10-01

    The Smart Weapons Test Range (SWTR) lies within the Yuma Proving Ground (YPG), Arizona. SWTR is a new facility constructed specifically for the development and testing of futuristic intelligent battlefield sensor networks. In this paper, results are presented for an extensive high-resolution geophysical characterization study at the SWTR site along with validation using 3-D modeling. In this study, several shallow seismic methods and novel processing techniques were used to generate a 3-D grid of earth seismic properties, including compressional (P) and shear (S) body-wave speeds (Vp and Vs), and their associated body-wave attenuation parameters (Qp, and Qs). These experiments covered a volume of earth measuring 1500 m by 300 m by 25 m deep (11 million cubic meters), centered on the vehicle test track at the SWTR site. The study has resulted in detailed characterizations of key geophysical properties. To our knowledge, results of this kind have not been previously achieved, nor have the innovative methods developed for this effort been reported elsewhere. In addition to supporting materiel developers with important geophysical information at this test range, the data from this study will be used to validate sophisticated 3-D seismic signature models for moving vehicles.

  9. Preliminary results of the CRISP 3D seismic experiment, offshore Costa Rica

    NASA Astrophysics Data System (ADS)

    Bangs, N. L.; McIntosh, K. D.; Silver, E. A.; Ranero, C. R.; Kluesner, J. W.; von Huene, R.; Cavanaugh, S.; Graf, S.; Cameselle, A. L.; Baracco, A. M.; Nuñez, E.

    2011-12-01

    In April and May of 2011, we acquired a new 3D seismic reflection data volume offshore Costa Rica, northwest of the Osa Peninsula. The goal of the survey was to examine the crustal structure and deformation history of this collision zone, and to clearly image the plate-boundary fault from the trench and into the seismogenic zone. These data will also help locate a deep site for riser drilling as part of the CRISP drilling program. The 3D survey covered 55 km across the upper shelf and slope, and into the trench. It extended 11 km along strike for a total survey area of 11 x 55 km. These data were acquired with the R/V Langseth using a 3300 cubic inch source shot every 50 m. We recorded the data on four 6-km-long, 468-channel streamers with 150m separation. We have preliminary results from processing 2D seismic lines extracted from the 3D volume, and from initial 3D volume processing. In the preliminary images we can trace strong seismic reflections from the plate-boundary fault down to 3 s two-way travel time (approx. 5 km depth) below the seafloor and 26 km landward from the trench. The plate-boundary fault reflection amplitudes decrease substantially with depth and are difficult to depict on these preliminary profiles. The upper plate structure shows numerous faults, many extending down to the plate-interface, and intense folding and faulting of the slope cover sequences. Currently these data are being processed by the Spanish oil company, Repsol, and should reveal far more detail with complete 3D processing.

  10. Sequence stratigraphy and 3-D seismic imaging in low-accommodation basins

    SciTech Connect

    Hardage, B.A.; Carr, D.L.; Hamilton, D.S.; Simmons, J.L. Jr. )

    1996-01-01

    Pennsylvanian-age rocks in several areas of the Midcontinent of the United States were deposited in low-accommodation basinal settings. Many sequences in these low-accommodation environments exhibit severe lateral heterogeneity because they have been extensively reworked by repeated transgressions and regressions. Consequently, the distinctive geometries of relic depositional features tend to be distorted or totally destroyed, in contrast to such geometries in high-accommodation basins where depositional topography, once buried, is rarely exposed to erosional processes. Our objective is to show how these thin and obscure low-accommodation sequences can be identified in well control and interpreted in 3-D seismic data volumes. Numerous, deep-rooted karst-collapse zones affected the areal continuity of many sequences in some Midcontinent basins. We combine sequence stratigraphy with 3-D seismic imaging to document that many of these karst-collapse zones originate at deep Ellenburger ( ) levels and then extend vertically for a distance of 2,000 ft (600 m) or more into Pennsylvanian-age rocks. We also offer evidence that properly chosen seismic attributes, calculated in thin, accurately defined seismic time windows that correspond to log-defined sequences, show compartmented reservoir facies in low-accommodation basins.

  11. Sequence stratigraphy and 3-D seismic imaging in low-accommodation basins

    SciTech Connect

    Hardage, B.A.; Carr, D.L.; Hamilton, D.S.; Simmons, J.L. Jr.

    1996-12-31

    Pennsylvanian-age rocks in several areas of the Midcontinent of the United States were deposited in low-accommodation basinal settings. Many sequences in these low-accommodation environments exhibit severe lateral heterogeneity because they have been extensively reworked by repeated transgressions and regressions. Consequently, the distinctive geometries of relic depositional features tend to be distorted or totally destroyed, in contrast to such geometries in high-accommodation basins where depositional topography, once buried, is rarely exposed to erosional processes. Our objective is to show how these thin and obscure low-accommodation sequences can be identified in well control and interpreted in 3-D seismic data volumes. Numerous, deep-rooted karst-collapse zones affected the areal continuity of many sequences in some Midcontinent basins. We combine sequence stratigraphy with 3-D seismic imaging to document that many of these karst-collapse zones originate at deep Ellenburger (?) levels and then extend vertically for a distance of 2,000 ft (600 m) or more into Pennsylvanian-age rocks. We also offer evidence that properly chosen seismic attributes, calculated in thin, accurately defined seismic time windows that correspond to log-defined sequences, show compartmented reservoir facies in low-accommodation basins.

  12. A global database of seismically and non-seismically triggered landslides for 2D/3D numerical modeling

    NASA Astrophysics Data System (ADS)

    Domej, Gisela; Bourdeau, Céline; Lenti, Luca; Pluta, Kacper

    2017-04-01

    Landsliding is a worldwide common phenomenon. Every year, and ranging in size from very small to enormous, landslides cause all too often loss of life and disastrous damage to infrastructure, property and the environment. One main reason for more frequent catastrophes is the growth of population on the Earth which entails extending urbanization to areas at risk. Landslides are triggered by a variety and combination of causes, among which the role of water and seismic activity appear to have the most serious consequences. In this regard, seismic shaking is of particular interest since topographic elevation as well as the landslide mass itself can trap waves and hence amplify incoming surface waves - a phenomenon known as "site effects". Research on the topic of landsliding due to seismic and non-seismic activity is extensive and a broad spectrum of methods for modeling slope deformation is available. Those methods range from pseudo-static and rigid-block based models to numerical models. The majority is limited to 2D modeling since more sophisticated approaches in 3D are still under development or calibration. However, the effect of lateral confinement as well as the mechanical properties of the adjacent bedrock might be of great importance because they may enhance the focusing of trapped waves in the landslide mass. A database was created to study 3D landslide geometries. It currently contains 277 distinct seismically and non-seismically triggered landslides spread all around the globe whose rupture bodies were measured in all available details. Therefore a specific methodology was developed to maintain predefined standards, to keep the bias as low as possible and to set up a query tool to explore the database. Besides geometry, additional information such as location, date, triggering factors, material, sliding mechanisms, event chronology, consequences, related literature, among other things are stored for every case. The aim of the database is to enable

  13. Serial sectioning methods for 3D investigations in materials science.

    PubMed

    Zankel, Armin; Wagner, Julian; Poelt, Peter

    2014-07-01

    A variety of methods for the investigation and 3D representation of the inner structure of materials has been developed. In this paper, techniques based on slice and view using scanning microscopy for imaging are presented and compared. Three different methods of serial sectioning combined with either scanning electron or scanning ion microscopy or atomic force microscopy (AFM) were placed under scrutiny: serial block-face scanning electron microscopy, which facilitates an ultramicrotome built into the chamber of a variable pressure scanning electron microscope; three-dimensional (3D) AFM, which combines an (cryo-) ultramicrotome with an atomic force microscope, and 3D FIB, which delivers results by slicing with a focused ion beam. These three methods complement one another in many respects, e.g., in the type of materials that can be investigated, the resolution that can be obtained and the information that can be extracted from 3D reconstructions. A detailed review is given about preparation, the slice and view process itself, and the limitations of the methods and possible artifacts. Applications for each technique are also provided. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Training toward Advanced 3D Seismic Methods for CO2 Monitoring, Verification, and Accounting

    SciTech Connect

    Christopher Liner

    2012-05-31

    The objective of our work is graduate and undergraduate student training related to improved 3D seismic technology that addresses key challenges related to monitoring movement and containment of CO{sub 2}, specifically better quantification and sensitivity for mapping of caprock integrity, fractures, and other potential leakage pathways. We utilize data and results developed through previous DOE-funded CO{sub 2} characterization project (DE-FG26-06NT42734) at the Dickman Field of Ness County, KS. Dickman is a type locality for the geology that will be encountered for CO{sub 2} sequestration projects from northern Oklahoma across the U.S. midcontinent to Indiana and Illinois. Since its discovery in 1962, the Dickman Field has produced about 1.7 million barrels of oil from porous Mississippian carbonates with a small structural closure at about 4400 ft drilling depth. Project data includes 3.3 square miles of 3D seismic data, 142 wells, with log, some core, and oil/water production data available. Only two wells penetrate the deep saline aquifer. In a previous DOE-funded project, geological and seismic data were integrated to create a geological property model and a flow simulation grid. We believe that sequestration of CO{sub 2} will largely occur in areas of relatively flat geology and simple near surface, similar to Dickman. The challenge is not complex geology, but development of improved, lower-cost methods for detecting natural fractures and subtle faults. Our project used numerical simulation to test methods of gathering multicomponent, full azimuth data ideal for this purpose. Our specific objectives were to apply advanced seismic methods to aide in quantifying reservoir properties and lateral continuity of CO{sub 2} sequestration targets. The purpose of the current project is graduate and undergraduate student training related to improved 3D seismic technology that addresses key challenges related to monitoring movement and containment of CO{sub 2

  15. Enhanced imaging of CO2 at the Ketzin storage site: Inversion of 3D time-lapse seismic data

    NASA Astrophysics Data System (ADS)

    Gil, M.; Götz, J.; Ivanova, A.; Juhlin, C.; Krawczyk, C. M.; Lüth, S.; Yang, C.

    2012-04-01

    The Ketzin test site, located near Berlin, is Europe's longest-operating on-shore CO2 storage site. As of December 2011, more than 56,000 tons of food grade CO2 has been injected since June 2008 in an anticlinal structure of the Northeast German Basin. The target reservoir consists of porous, brine bearing sandstone units of the Upper Triassic Stuttgart Formation at approximately 630 to 650 m depth. In order to enhance the understanding of the structural geometry of the site and to investigate the extension of the CO2-plume, several geophysical monitoring methods are being applied at Ketzin, among these are active seismic measurements, geoelectrics and borehole measurements. Among the various seismic techniques (e.g. 2D reflection surveys, crosshole tomography, Vertical Seismic Profiling, 2D- and 3D-Moving Source Profiling) employed at this pilot site, 3D time-lapse reflection surveys are an important component. The baseline 3D survey was acquired in 2005 and the first repeat measurements were performed in 2009 after injection of about 22,000 tons of CO2. The second repeat survey is planned to be carried out in fall 2012. These measurements allow the time-lapse signature of the injected CO2 to be imaged. The time-lapse amplitude variation attributed to the injected CO2 in the reservoir matches, considering detection limits of seismic surface measurements, the expected distribution of the CO2 plume derived from reservoir simulations. Previous attempts towards a quantitative interpretation were based on integrative considerations of different types of geophysical measurements using strict assumptions and characterized by large error bars. In order to increase the resolution and reliability of the data and to improve estimation of rock properties and especially to enhance the imaging resolution of the CO2-plume, the time-lapse 3D seismic data have now been inverted for seismic impedances with different methods, which is the focus of this presentation. One difficulty

  16. Fast 3D elastic micro-seismic source location using new GPU features

    NASA Astrophysics Data System (ADS)

    Xue, Qingfeng; Wang, Yibo; Chang, Xu

    2016-12-01

    In this paper, we describe new GPU features and their applications in passive seismic - micro-seismic location. Locating micro-seismic events is quite important in seismic exploration, especially when searching for unconventional oil and gas resources. Different from the traditional ray-based methods, the wave equation method, such as the method we use in our paper, has a remarkable advantage in adapting to low signal-to-noise ratio conditions and does not need a person to select the data. However, because it has a conspicuous deficiency due to its computation cost, these methods are not widely used in industrial fields. To make the method useful, we implement imaging-like wave equation micro-seismic location in a 3D elastic media and use GPU to accelerate our algorithm. We also introduce some new GPU features into the implementation to solve the data transfer and GPU utilization problems. Numerical and field data experiments show that our method can achieve a more than 30% performance improvement in GPU implementation just by using these new features.

  17. New comprehensive standard seismic noise models and 3D seismic noise variation for Morocco territory, North Africa, obtained using seismic broadband stations

    NASA Astrophysics Data System (ADS)

    El Fellah, Younes; El-Aal, Abd El-Aziz Khairy Abd; Harnafi, Mimoun; Villaseñor, Antonio

    2017-05-01

    In the current work, we constructed new comprehensive standard seismic noise models and 3D temporal-spatial seismic noise level cubes for Morocco in north-west Africa to be used for seismological and engineering purposes. Indeed, the original global standard seismic noise models published by Peterson (1993) and their following updates by Astiz and Creager (1995), Ekström (2001) and Berger et al. (2003) had no contributing seismic stations deployed in North Africa. Consequently, this preliminary study was conducted to shed light on seismic noise levels specific to north-west Africa. For this purpose, 23 broadband seismic stations recently installed in different structural domains throughout Morocco are used to study the nature and characteristics of seismic noise and to create seismic noise models for Morocco. Continuous data recorded during 2009, 2010 and 2011 were processed and analysed to construct these new noise models and 3D noise levels from all stations. We compared the Peterson new high-noise model (NHNM) and low-noise model (NLNM) with the Moroccan high-noise model (MHNM) and low-noise model (MLNM). These new noise models are comparable to the United States Geological Survey (USGS) models in the short period band; however, in the period range 1.2 s to 1000 s for MLNM and 10 s to 1000 s for MHNM display significant variations. This variation is attributed to differences in the nature of seismic noise sources that dominate Morocco in these period bands. The results of this study have a new perception about permanent seismic noise models for this spectacular region and can be considered a significant contribution because it supplements the Peterson models and can also be used to site future permanent seismic stations in Morocco.

  18. Investigation of Pre-Earthquake Ionospheric Disturbances by 3D Tomographic Analysis

    NASA Astrophysics Data System (ADS)

    Yagmur, M.

    2016-12-01

    Ionospheric variations before earthquakes have been widely discussed phenomena in ionospheric studies. To clarify the source and mechanism of these phenomena is highly important for earthquake forecasting. To well understanding the mechanical and physical processes of pre-seismic Ionospheric anomalies that might be related even with Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling, both statistical and 3D modeling analysis are needed. For these purpose, firstly we have investigated the relation between Ionospheric TEC Anomalies and potential source mechanisms such as space weather activity and lithospheric phenomena like positive surface electric charges. To distinguish their effects on Ionospheric TEC, we have focused on pre-seismically active days. Then, we analyzed the statistical data of 54 earthquakes that M≽6 between 2000 and 2013 as well as the 2011 Tohoku and the 2016 Kumamoto Earthquakes in Japan. By comparing TEC anomaly and Solar activity by Dst Index, we have found that 28 events that might be related with Earthquake activity. Following the statistical analysis, we also investigate the Lithospheric effect on TEC change on selected days. Among those days, we have chosen two case studies as the 2011 Tohoku and the 2016 Kumamoto Earthquakes to make 3D reconstructed images by utilizing 3D Tomography technique with Neural Networks. The results will be presented in our presentation. Keywords : Earthquake, 3D Ionospheric Tomography, Positive and Negative Anomaly, Geomagnetic Storm, Lithosphere

  19. Seismogenesis of clustered seismicity beneath the Kangra-Chamba sector of northwest Himalaya: Constraints from 3D local earthquake tomography

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Arora, B. R.; Mukhopadhyay, Sagarika; Yadav, D. K.

    2013-01-01

    To investigate subsurface structure and seismogenic layers, 3D velocity inversion was carried out in the source zone of 1905 Kangra earthquake (M8.0) in the northwestern Himalaya. P-wave and S-wave phase data of 159 earthquakes recorded by a network of 21 stations were used for this purpose. Inverted velocity tomograms up to a depth range of 18 km show significant variations of 14% in Vp and Vs and 6% in the Vp/Vs across the major tectonic zones in the region. Synthesis of seismicity pattern, velocity structure, distinctive focal mechanisms coupled with nature of stress distribution allows mapping of three different source regions that control regional seismotectonics. Accumulating strains are partly consumed by sliding of Chamba Nappe to the southwest through reverse-fault movements along Chamba/Panjal/Main Boundary Thrusts. This coupled with normal-fault type displacements along Chenab Normal Fault in the north account for low magnitude widespread seismicity in upper 8-10 km of the crust. At intermediate depths from 8 to 15 km, adjusting to residual compressive stresses, the detachment or lower end of the MBT slips to produce thrust dominated seismicity. Nucleation of secondary stresses in local NE-SW oriented structure interacts in complex manner with regional stresses to generate normal type earthquakes below the plane of detachment and therefore three seismic regimes at different depths produce intense seismicity in a block of 30 × 30 km2 centered NE to the epicenter of Kangra earthquake.

  20. 3D Velocity Structure of Chukou Fault Area, Taiwan from Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Chen, C.; Chang, W.; Jian, W.

    2009-12-01

    In this study, we used the seismic data that recorded by the broadband stations which deployed around the Chukou fault area, Taiwan. We have chosen 1661 earthquake events with high quality records in this research. The waveform cross correlation technique is applied to calculate the 143086 pairs of waveform data. By combining with data from the seismic catalog, there are 342202 absolute travel-time pairs through the double difference tomography method to relocate the seismicity and invert the 3D velocity structures beneath the Chukou fault area. Due to Taiwan Island is located in an active boundary zone between the Eurasia continental and Philippine Sea plates, the violent collision between the two plates which causes a series of imbricate fold-thrust belts to form between the western foothills and the coastal plain. The Chukou fault is just the boundary between the fold-thrust belts and the coastal plain in the Chia-Nan area, Taiwan. The seismotectonic structure beneath this area is more complex. From many studies, velocity structure can be used as an indicator of the geometry of fault and the general aspect of tectonics. Therefore, the first goal of this research is to analyze the degree of correlation between the velocity structure and the characteristics of seismicity and the tectonic implications of the area. The second intention is to study the distribution of seismic events and its association with fault activities. Our results indicate that the variation of velocity structure beneath fault area is caused by local geological structures, complex fault crossing. We also find that most earthquakes occur in the area that has Vp/Vs gradient varying rapidly. Finally, both using catalog and cross-correlation data in the inversion procedure are not only exhibit better resolution, but also can obtain the detail 3D velocity structure beneath the fault zone.

  1. 3D Numerical Simulation on the Sloshing Waves Excited by the Seismic Shacking

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Wu, Tso-Ren

    2016-04-01

    In the event of 2015 Nepal earthquake, a video clip broadcasted worldwide showed a violent water spilling in a hotel swimming pool. This sloshing phenomenon indicates a potential water loss in the sensitive facilities, e.g. the spent fuel pools in nuclear power plant, has to be taken into account carefully under the consideration of seismic-induced ground acceleration. In the previous studies, the simulation of sloshing mainly focused on the pressure force on the structure by using a simplified Spring-Mass Method developed in the field of solid mechanics. However, restricted by the assumptions of plane water surface and limited wave height, significant error will be made in evaluating the amount of water loss in the tank. In this paper, the computational fluid dynamical model, Splash3D, was adopted for studying the sloshing problem accurately. Splash3D solved 3D Navier-Stokes Equation directly with Large-Eddy Simulation (LES) turbulent closure. The Volume-of-fluid (VOF) method with piecewise linear interface calculation (PLIC) was used to track the complex breaking water surface. The time series acceleration of a design seismic was loaded to excite the water. With few restrictions from the assumptions, the accuracy of the simulation results were improved dramatically. A series model validations were conducted by compared to a 2D theoretical solution, and a 3D experimental data. Good comparisons can be seen. After the validation, we performed the simulation for considering a sloshing case in a rectangular water tank with a dimension of 12 m long, 8 m wide, 8 m deep, which contained water with 7 m in depth. The seismic movement was imported by considering time-series acceleration in three dimensions, which were about 0.5 g to 1.2 g in the horizontal directions, and 0.3 g to 1 g in the vertical direction. We focused the discussions on the kinematics of the water surface, wave breaking, velocity field, pressure field, water force on the side walls, and, most

  2. Seismic Response of 3D Steel Buildings considering the Effect of PR Connections and Gravity Frames

    PubMed Central

    Haldar, Achintya; López-Barraza, Arturo; Rivera-Salas, J. Luz

    2014-01-01

    The nonlinear seismic responses of 3D steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are studied explicitly considering the contribution of the IGF. The effect on the structural response of the stiffness of the beam-to-column connections of the IGF, which is usually neglected, is also studied. It is commonly believed that the flexibility of shear connections is negligible and that 2D models can be used to properly represent 3D real structures. The results of the study indicate, however, that the moments developed on columns of IGF can be considerable and that modeling buildings as plane frames may result in very conservative designs. The contribution of IGF to the lateral structural resistance may be significant. The contribution increases when their connections are assumed to be partially restrained (PR). The incremented participation of IGF when the stiffness of their connections is considered helps to counteract the no conservative effect that results in practice when lateral seismic loads are not considered in IGF while designing steel buildings with PMRF. Thus, if the structural system under consideration is used, the three-dimensional model should be used in seismic analysis and the IGF and the stiffness of their connections should be considered as part of the lateral resistance system. PMID:24995357

  3. 3D Seismic Flexure Analysis for Subsurface Fault Detection and Fracture Characterization

    NASA Astrophysics Data System (ADS)

    Di, Haibin; Gao, Dengliang

    2016-10-01

    Seismic flexure is a new geometric attribute with the potential of delineating subtle faults and fractures from three-dimensional (3D) seismic surveys, especially those overlooked by the popular discontinuity and curvature attributes. Although the concept of flexure and its related algorithms have been published in the literature, the attribute has not been sufficiently applied to subsurface fault detection and fracture characterization. This paper provides a comprehensive study of the flexure attribute, including its definition, computation, as well as geologic implications for evaluating the fundamental fracture properties that are essential to fracture characterization and network modeling in the subsurface, through applications to the fractured reservoir at Teapot Dome, Wyoming (USA). Specifically, flexure measures the third-order variation of the geometry of a seismic reflector and is dependent on the measuring direction in 3D space; among all possible directions, flexure is considered most useful when extracted perpendicular to the orientation of dominant deformation; and flexure offers new insights into qualitative/quantitative fracture characterization, with its magnitude indicating the intensity of faulting and fracturing, its azimuth defining the orientation of most-likely fracture trends, and its sign differentiating the sense of displacement of faults and fractures.

  4. Seismic response of 3D steel buildings considering the effect of PR connections and gravity frames.

    PubMed

    Reyes-Salazar, Alfredo; Bojórquez, Edén; Haldar, Achintya; López-Barraza, Arturo; Rivera-Salas, J Luz

    2014-01-01

    The nonlinear seismic responses of 3D steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are studied explicitly considering the contribution of the IGF. The effect on the structural response of the stiffness of the beam-to-column connections of the IGF, which is usually neglected, is also studied. It is commonly believed that the flexibility of shear connections is negligible and that 2D models can be used to properly represent 3D real structures. The results of the study indicate, however, that the moments developed on columns of IGF can be considerable and that modeling buildings as plane frames may result in very conservative designs. The contribution of IGF to the lateral structural resistance may be significant. The contribution increases when their connections are assumed to be partially restrained (PR). The incremented participation of IGF when the stiffness of their connections is considered helps to counteract the no conservative effect that results in practice when lateral seismic loads are not considered in IGF while designing steel buildings with PMRF. Thus, if the structural system under consideration is used, the three-dimensional model should be used in seismic analysis and the IGF and the stiffness of their connections should be considered as part of the lateral resistance system.

  5. Detection of ancient morphology and potential hydrocarbon traps using 3-D seismic data and attribute analysis

    SciTech Connect

    Heggland, R.

    1995-12-31

    This paper presents the use of seismic attributes on 3D data to reveal Tertiary and Cretaceous geological features in Norwegian block 9/2. Some of the features would hardly be possible to map using only 2D seismic data. The method which involves a precise interpretation of horizons, attribute analysis and manipulation of colour displays, may be useful when studying morphology, faults and hydrocarbon traps. The interval of interest in this study was from 0 to 1.5 s TWT. Horizontal displays (timeslices and attribute maps), seemed to highlight very nicely geological features such as shallow channels, fractures, karst topography and faults. The attributes used for mapping these features were amplitude, total reflection energy (a volume or time interval attribute), dip and azimuth. The choice of colour scale and manipulation of colour displays were also critical for the results. The data examples clearly demonstrate how it is possible to achieve a very detailed mapping of geological features using 3D seismic data and attribute analysis. The results of this study were useful for the understanding of hydrocarbon migration paths and hydrocarbon traps.

  6. 3D seismic denoising based on a low-redundancy curvelet transform

    NASA Astrophysics Data System (ADS)

    Cao, Jingjie; Zhao, Jingtao; Hu, Zhiying

    2015-08-01

    Contamination of seismic signal with noise is one of the main challenges during seismic data processing. Several methods exist for eliminating different types of noises, but optimal random noise attenuation remains difficult. Based on multi-scale, multi-directional locality of curvelet transform, the curvelet thresholding method is a relatively new method for random noise elimination. However, the high redundancy of a 3D curvelet transform makes its computational time and memory for massive data processing costly. To improve the efficiency of the curvelet thresholding denoising, a low-redundancy curvelet transform was introduced. The redundancy of the low-redundancy curvelet transform is approximately one-quarter of the original transform and the tightness of the original transform is also kept, thus the low-redundancy curvelet transform calls for less memory and computational resource compared with the original one. Numerical results on 3D synthetic and field data demonstrate that the low-redundancy curvelet denoising consumes one-quarter of the CPU time compared with the original curvelet transform using iterative thresholding denoising when comparable results are obtained. Thus, the low-redundancy curvelet transform is a good candidate for massive seismic denoising.

  7. 3D Seismic Flexure Analysis for Subsurface Fault Detection and Fracture Characterization

    NASA Astrophysics Data System (ADS)

    Di, Haibin; Gao, Dengliang

    2017-03-01

    Seismic flexure is a new geometric attribute with the potential of delineating subtle faults and fractures from three-dimensional (3D) seismic surveys, especially those overlooked by the popular discontinuity and curvature attributes. Although the concept of flexure and its related algorithms have been published in the literature, the attribute has not been sufficiently applied to subsurface fault detection and fracture characterization. This paper provides a comprehensive study of the flexure attribute, including its definition, computation, as well as geologic implications for evaluating the fundamental fracture properties that are essential to fracture characterization and network modeling in the subsurface, through applications to the fractured reservoir at Teapot Dome, Wyoming (USA). Specifically, flexure measures the third-order variation of the geometry of a seismic reflector and is dependent on the measuring direction in 3D space; among all possible directions, flexure is considered most useful when extracted perpendicular to the orientation of dominant deformation; and flexure offers new insights into qualitative/quantitative fracture characterization, with its magnitude indicating the intensity of faulting and fracturing, its azimuth defining the orientation of most-likely fracture trends, and its sign differentiating the sense of displacement of faults and fractures.

  8. From 3D to 4D seismic tomography at El Hierro Island (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Garcia-Yeguas, A.; Koulakov, I.; Jakovlev, A.; Ibáñez, J. M.

    2012-04-01

    In this work we are going to show the advantages of a dynamic tomography 4D, versus a static image 3D related with a volcanic reactivation and eruption at El Hierro island (Canary Islands, Spain). In this process a high number of earthquakes before and during the eruptive processes have been registered. We are going to show a 3D image as an average of the velocity structure and then the characteristics and physical properties on the medium, including the presence or not of magma. This image will be complemented with its evolution along the time, observing its volcanic dynamic and its influence over the medium properties, including its power as an important element on early warnings protocols. After more than forty years of quiet at Canary Islands, since 1971 with Teneguía eruption at La Palma Island, and more than 200 years on El Hierro Island (The last eruption known at El Hierro took place in 1793, volcán de Lomo Negro), on 19th July on 2011 the Spanish seismic national network, administered by IGN (Instituto Geográfico Nacional), detected an increase of local seismic activity below El Hierro island (Canary Islands, Spain). Since this moment an intense swarm took place, with more than 11000 events, until 11th December, with magnitudes (MLg) from 0.2 to 4.4. In this period two eruptive processes have been declared in front of the South coast of El Hierro island, and they have not finished yet. This seismic swarm has allowed carrying out a 3D seismic tomography, using P and S waves traveltimes. It has showed a low velocity from the North to the South. On the other hand, we have performed a 4D seismic tomography, taking the events occurred at different intervals of time. We can observe the evolution of the negative anomaly along the time, from the North to the South, where has taken place La Restinga submarine eruption. 4D seismic tomography is an innovative and powerful tool able to show the evolution in time of a volcanic process.

  9. High-resolution imaging of crustal melts using 3D full-waveform seismic inversion

    NASA Astrophysics Data System (ADS)

    Warner, M.; Morgan, J. V.

    2013-12-01

    A newly practical seismic imaging technique, 3D full-waveform inversion (FWI), now has the ability to image zones of melt and melt pathways throughout the crust with a better resolution than any other geophysical method. 3D FWI has recently changed practice within the petroleum industry where it is used to obtain high-resolution high-fidelity models of physical properties in the sub-surface that are both interpreted directly and used to improve the migration of deeper reflections. This technology has been spectacularly successful in improving the imaging of reservoirs beneath shallow heterogeneities produced by, for example, gas clouds, buried fluvial channels, carbonate reefs and salt bodies. During FWI, the sub-surface model is recovered principally by using the low-frequency transmitted, refracted portion of the wavefield which is most sensitive to the macro-velocity structure. In the petroleum industry, these inversions are now routinely performed using long-offset surface-streamer and ocean-bottom data to maximum source-receiver offsets of about 15 km, leading to a maximum penetration depth of around 5 km. Using longer offsets, it is possible to extend this technology to image deeper crustal targets. Localised zones of partial melt produce large changes in p-wave and s-wave properties that are restricted in their spatial extent, and that therefore form ideal targets for 3D FWI. We have performed a suite of tests to explore the use of 3D FWI in imaging melt distribution beneath the active volcano of Montserrat. We built a model of the subsurface using a 3D travel-time tomographic model obtained from the SEA CALIPSO experiment. We added two magma chambers in accordance with a model obtained using surface-elevation changes and geochemical data. We used a wide-angle, wide-azimuth acquisition geometry to generate a fully-elastic synthetic seismic dataset, added noise, and inverted the windowed transmitted arrivals only. We used an elastic code for the forward

  10. Time-lapse analysis of sparse 3D seismic data from the CO2 storage pilot site at Ketzin, Germany

    NASA Astrophysics Data System (ADS)

    Ivandic, M.; Yang, C.; Lüth, S.; Cosma, C.; Juhlin, C.

    2012-04-01

    Capture and geological storage of CO2 is considered to be a feasible method for reducing carbon emissions. In April 2004, a research pilot project in the German town of Ketzin started as the first onshore CO2 storage project in Europe. Injection started in June 2008 and until the latest repeat survey in February 2011 around 45 kilotons of CO2 had been injected into a saline aquifer at approximately 630-650 m depth. Different seismic methods, such as time-lapse Vertical Seismic Profiling (VSP), Crosswell, Moving Source Profiling (MSP) and surface seismics have been employed to detect and monitor changes in the reservoir. We present here time-lapse results from sparse 3D seismic surveying with a "star" geometry, i.e. with a radial distribution of acquisition profiles directed towards the approximate location of the injection well, which were acquired to link downhole surveys with full 3D surface seismic surveys. The main objectives of the sparse 3D surveys were (1) to identify changes in the seismic response related to the injection of CO2 between the repeat surveys and baseline survey and (2) to compare these results with those from the repeat 3D seismic survey. The results are consistent with the 3D seismic time-lapse studies over the injection site and show that the sparse 3D geometry can be used to qualitatively map the migration of the CO2 plume within the saline reservoir, as well as potential migration out of the reservoir rock at a significantly lower effort than the full 3D surveying. The latest repeat survey indicates preferential migration of the CO2 to the west. Both sparse 3D repeat surveys show that the CO2 is being confined within the aquifer, implying that there is no leakage into the caprock at the time of the repeat surveys. The same observation was obtained from the 3D dataset.

  11. Pennsylvanian Subsurface Sequence Stratigraphy Based on 3D Seismic and Wireline Data in Western Osage County, Oklahoma

    NASA Astrophysics Data System (ADS)

    West, Alexander

    The Pennsylvanian System in the Mid-Continent United States has been studied for nearly a century. In north central Oklahoma, the Pennsylvanian is primarily composed of cyclothems. These cyclothems are sequences of alternating carbonate, clastic, and shale members. Because of this, these zones can be difficult to differentiate. This project provides valuable insight into better understanding the Pennsylvanian System in western Osage County, Oklahoma. The scope of this project is to perform a subsurface study to produce a detailed interpretation of the depositional history and stratigraphy of Pennsylvanian sequences in western Osage County. This study features 3D seismic and well log investigations that will be used together for local and regional subsurface interpretations. The seismic surveys used in the project are the Wild Creek and Gray Horse 3D surveys in western Osage County. The well logs, digital and raster, provide respectable well control for western Osage County. Together, interpretations from the seismic data and well logs will be used to provide a better understanding of the subsurface stratigraphy and depositional history of Pennsylvanian sequences in western Osage County, Oklahoma.

  12. An Integrated Multi-component Processing and Interpretation Framework for 3D Borehole Seismic Data

    SciTech Connect

    M. Karrenbach

    2004-04-01

    This report covers the October 2003 until March 2004 time period. Work has continued successfully on several tasks 1 through 7. Most of these tasks have been executed independently. Due to availability of manpower during that time period we progressed steadily and completed some of the tasks, while others are still on going. We achieved the goals that we had set up in the task schedule. Reviewing the results of this work period indicates that our plan is on schedule and we did not encounter any unforeseen problems. The work plan will continue as projected. Several independent tasks pursuant the statement of project objectives have been executed simultaneously and are still on-going. This report summarizes the selection, test processing and test flow generation of a relevant 3D borehole seismic high-resolution test dataset. This multi-component data set is suitable for future use in this project due to data quality and unique acquisition characteristics. This report shows initial processing results that supported the data selection scheduled for Task 1. Use of real data is augmented by the creating a 3D layered synthetic geologic model in which multi-component 3D borehole seismic data were generated using 3D ray tracing. A gridded surface representation of the reflection interfaces as well as fully populated velocity grids were generated and archived. The model consists of a moderately dipping geologic setting with horizon undulations. A realistic velocity variation is used in between the three layers. Acquisition was simulated from a set of equidistant source locations at the surface of the model, while a close to vertical VSP well was used to capture the wave field data. The source pattern was close to a staggered grid pattern. Multi-component particle displacements were recorded every 50 ft down with an array length of 4,000 ft. P-P as well as P-S reflections were specified in the resulting wave field. We ensured a large enough aperture with enough fine sampling

  13. 3-D Seismic Exploration Project, Ute Indian Tribe, Uintah and Ouray Reservation, Uintah County, Utah

    SciTech Connect

    Eckels, Marc T.

    2002-09-09

    The objectives of this North Hill Creek 3-D seismic survey were to: (1) cover as large an area as possible with available budget; (2) obtain high quality data throughout the depth range of the prospective geologic formations of 2,000' to 12,000' to image both gross structures and more subtle structural and stratigraphic elements; (3) overcome the challenges posed by a hard, reflective sandstone that cropped out or was buried just a few feet below the surface under most of the survey area; and (4) run a safe survey.

  14. Mini 3D seismic surveys of mud volcanoes in the Kumano Basin

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Morita, S.; Ashi, J.

    2007-12-01

    Kumano Basin is a forearc basin of the Nankai Trough subduction zone. Eight mud volcanoes have been found in the basin from previous diving and side-scan sonar surveys. Seismic sections clearly showed the BSR widely developed in the basin. The existence of the BSR near the mud volcanoes suggest that the methane gas dissociated from the hydrate excesses the activity of the mud volcanoes. To reveal the relation between activity of mud volcanoes and hydrate, we have conducted mini 3D seismic experiments. The experiments were separated to two phases; first experiment was conducted in 2004 covering Daigo and Dairoku Kumano Knolls (KK5 and KK6), and second was in 2006 covering Daisan Kumano Knoll (KK3). KK5 is located close to KK6 so they are called as twin mud volcanoes. Previous observation by diving and result from piston core sample analysis revealed following features; •KK5 is active now, or has been recently active. •KK6 is not active now. It stopped the activity at ~25,000 years ago. •KK3 is not active now, but it had been active more recent than KK6. We investigated the structure in and around the mud volcanoes in different phases of activity. All of three mud volcanoes studied have 'umbrella structure' beneath the seafloor. This structure is onlapped by the surrounding sedimentary sequence, which suggests that the 'umbrella structure' was formed by the ancient mud volcanism buried by the basin sediment. In KK3, accumulation of the umbrella (three or four times) is observed. This indicates the KK3 has been activated periodically in the last 500,000 years. BSR is continuously traceable beneath KK6, but it is vanished beneath the center of KK5. Beneath KK3, the BSR is also vanished just beneath its center, but the area without BSR is narrower then KK5. The observation on the BSR would suggest strong relationship between mud volcano activity and gas-hydrate.

  15. 3D seismic attribute-assisted analysis of microseismic events in the Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Hart, Ariel Kelton

    Microseismic monitoring is often used during the process of oil and gas exploitation to monitor seismicity that may be triggered by hydraulic fracturing, a common practice in the Appalachian Basin. Anthropogenically-induced minor upward fracture growth is not uncommon in the Marcellus shale; however, in the area of study, significant microseismic activity was registered above the target zone. In order to ascertain whether out-of-zone growth might have been predictable and identify which areas are more likely to experience brittle failure first, 3D seismic and microseismic data were analyzed with a focus on better understanding variations in the acoustic properties associated with unconventional naturally fractured reservoirs. Ant Tracking was used to identify areas of increased local seismic discontinuity, as these areas are generally more intensely deformed and may represent zones of increased fracture intensity. Ant Tracking results reveal discontinuities in the Marcellus are oriented approximately at N52E and N41W; discontinuities do not coincide with N25E trending folds apparent in the 3D seismic, but tend to follow deeper structural trends instead. These discontinuity orientations are interpreted to be a result of continued movement on deeper faults throughout the Paleozoic; these faults possibly acted as seed points for fractures further upsection and potentially led to the precipitation of the large N25E trending imbricate backthrusts seen in the 3D seismic. The reservoir's response to hydraulic fracturing also provided insights into local stress anisotropy and into optimal well and stage spacing needed to maximize drainage area and locate additional wells during the field development phase. Microseismic, well, and pump data used to gauge the reservoir's response to a hydraulic fracture treatment indicated that the number of stages, lateral length, total proppant volume, and fracture energy heavily influence how a well produces. SHmax in the area is oriented

  16. Full-Waveform Validation of a 3D Seismic Model for Western US

    NASA Astrophysics Data System (ADS)

    Maceira, M.; Larmat, C. S.; Ammon, C. J.; Chai, C.; Herrmann, R. B.

    2014-12-01

    Since the initiation of tomographic studies in the 1970s, geoscientists have advanced the art of inferring 3D variations in the subsurface using collections of geophysical (primarily seismic) observables recorded at or near Earth's surface. Advances have come from improvement and enhancement of the available data and from research on theoretical and computational improvements to tomographic and generalized inverse methods. In the last decade, utilizing dense array datasets, these efforts have led to unprecedented 3D images of the subsurface. Understandably, less effort has been expended on model validation to provide an absolute assessment of model uncertainty. Generally models constructed with different data sets and independent computational codes are assessed with geological reasonability and compared other models to gain confidence. The question of "How good is a particular 3D geophysical model at representing the Earth's true nature?" remains largely unaddressed at a time when 3D Earth models are used for both societal and energy security. In the last few years, opportunities have arisen in earth-structure imaging, including the advent of new methods in computational seismology and statistical sciences. We use the unique and extensive High Performance Computing resources available at Los Alamos National Laboratory to explore approaches to realistic model validation. We present results from a study focused on validating a 3D model for the western United States generated using a joint inversion simultaneously fitting interpolated teleseismic P-wave receiver functions, Rayleigh-wave group-velocity estimates between 7 and 250 s period, and high-wavenumber filtered Bouguer gravity observations. Validation of the obtained model is performed through systematic comparison of observed and predicted seismograms generated using the Spectral Element Method, which is a direct numerical solution for full waveform modeling in 3D models, with accuracy of spectral methods.

  17. Seismic hazard of the Northern Apennines based on 3D seismic sources

    NASA Astrophysics Data System (ADS)

    Martelli, L.; Santulin, M.; Sani, F.; Tamaro, A.; Bonini, M.; Rebez, A.; Corti, G.; Slejko, D.

    2017-09-01

    Seismic hazard has been computed for the Northern Apennines in northern Italy based on a new seismogenic zonation. This zonation considers inclined (dipping) planes as seismogenic sources, defined on the basis of all the seismotectonic information available so far. Although these geometries are extremely rough because they simplify with a few inclined elements the totality of faults constituting a source, this model mimics the tectonic style better than that based on horizontal planes. Nevertheless, for a comparison between the new ground motions obtained and those available in the literature, the plane version of the zonation has been developed, where horizontal areas (the standard seismogenic zones), representing the surficial projection of the inclined planes, are used as seismogenic sources.

  18. 3D insight into fault geometries, deformation, and fluid-migration within the Hosgri Fault Zone offshore central California: Results from high-resolution 3D seismic data

    NASA Astrophysics Data System (ADS)

    Kluesner, J.; Brothers, D. S.; Johnson, S. Y.; Watt, J. T.

    2015-12-01

    High-resolution 3D seismic P-Cable data and advanced seismic attribute analyses were used to detect and interpret complex strike-slip fault geometries, deformation patterns, and fluid-pathways across a portion of the Hosgri Fault Zone (HFZ) offshore central California. Combination of the fault attribute results with structural analysis provides 3D insight into the geometry and internal structure of restraining and releasing bends, step-over zones, fault convergence zones, and apparent paired fault bends. The 3D seismic volume covers a 13.7 km2 region along the HFZ offshore of Point Sal and was collected in 2012 as part of the PG&E Central California Seismic Imaging Project (PG&E, 2014). Application of the fault attribute workflow isolated and delineated fault strands within the 3D volume. These results revealed that the northern and southern edges of the survey region are characterized by single fault strands that exhibit an approximate 6° change in strike across the 3D volume. Between these single faults strands is a complex network of fault splays, bends, stepovers, and convergence zones. Structural analysis reveals that the southern portion of the HFZ in the region is characterized by transtensional deformation, whereas transpressional-related folding dominates the central and northern portions of the HFZ. In the central region, convergence of the Lions Head Fault from the southeast results in an apparent impinging block, leading to development of a "paired fault bend" to the west. Combination of the fault and "chimney" attribute results indicates a strong connection between faults and fluid-migration pathways. Fluid-pathways are concentrated along discrete faults in the transtensional zones, but appear to be more broadly distributed amongst fault bounded anticlines and structurally controlled traps in the transpressional zones.

  19. High-resolution 3D seismic model of the crustal and uppermost mantle structure in Poland

    NASA Astrophysics Data System (ADS)

    Grad, Marek; Polkowski, Marcin; Ostaficzuk, Stanisław R.

    2016-01-01

    In the area of Poland a contact between the Precambrian and Phanerozoic Europe and the Carpathians has a complicated structure and a complex P-wave velocity of the sedimentary cover, crystalline crust, Moho depth and the uppermost mantle. The geometry of the uppermost several kilometers of sediments is relatively well recognized from over 100,000 boreholes. The vertical seismic profiling (VSP) from 1188 boreholes provided detailed velocity data for regional tectonic units and for stratigraphic successions from Permian to the Tertiary and Quaternary deposits. These data, however, do not provide information about the velocity and basement depth in the central part of the Trans-European suture zone (TESZ) and in the Carpathians. So, the data set is supplemented by 2D velocity models from 32 deep seismic sounding refraction profiles which also provide information about the crust and uppermost mantle. Together with the results of other methods: vertical seismic profiling, magnetotelluric, allow for the creation of a detailed, high-resolution 3D model for the entire Earth's crust and the uppermost mantle down to a depth of 60 km. The thinnest sedimentary cover in the Mazury-Belarus anteclise is only 0.3 to 1 km thick, which increases to 7 to 8 km along the East European Craton (EEC) margin, and 9 to 12 km in the TESZ. The Variscan domain is characterized by a 1-4 km thick sedimentary cover, while the Carpathians are characterized by very thick sedimentary layers, up to about 20 km. The crystalline crust is differentiated and has a layered structure. The crust beneath the West European Platform (WEP; Variscan domain) is characterized by P-wave velocities of 5.8-6.6 km/s. The upper and middle crusts beneath the EEC are characterized by velocities of 6.1-6.6 km/s, and are underlain by a high velocity lower crust with a velocity of about 7 km/s. A general decrease in velocity is observed from the older to the younger tectonic domains. The TESZ is associated with a steep dip

  20. 3D interpretation of SHARAD radargram data using seismic processing routines

    NASA Astrophysics Data System (ADS)

    Kleuskens, M. H. P.; Oosthoek, J. H. P.

    2009-04-01

    Ground penetrating radar on board a satellite has entered the field of planetary geology. Two radars enable subsurface observations of Mars. In 2003, ESA launched the Mars Express equipped with MARSIS, a low frequency radar which was able to detect only the base of the ice caps. Since December 2006, the Shallow Radar (SHARAD) of Agenzia Spaziale Italiana (ASI) on board the NASA Mars Reconnaissance Orbiter (MRO) is active in orbit around Mars. The SHARAD radar covers the frequency band between 15 and 25 MHz. The vertical resolution is about 15 m in free space. The horizontal resolution is 300-1000 m along track and 1500-8000 m across track. The radar penetrates the subsurface of Mars up to 2 km deep, and is capable of detecting multiple reflections in the ice caps of Mars. Considering the scarcity of planetary data relative to terrestrial data, it is essential to combine all available types of data of an area of interest. Up to now SHARAD data has only been interpreted separately as 2D radargrams. The Geological Survey of the Netherlands has decades of experience in interpreting 2D and 3D seismic data of the Dutch subsurface, especially for the 3D interpretation of reservoir characteristics of the deeper subsurface. In this abstract we present a methodology which can be used for 3D interpretation of SHARAD data combined with surface data using state-of-the art seismic software applied in the oil and gas industry. We selected a region that would be most suitable to demonstrate 3D interpretation. The Titania Lobe of the North Polar ice cap was selected based on the abundancy of radar data and the complexity of the ice lobe. SHARAD data is released to the scientific community via the Planetary Data System. It includes ‘Reduced Data Records' (RDR) data, a binary format which contains the radargram. First the binary radargram data and corresponding coordinates were combined and converted to the commonly used seismic seg-y format. Second, we used the reservoir

  1. Preliminary investigations on 3D PIC simulation of DPHC structure using NEPTUNE3D code

    NASA Astrophysics Data System (ADS)

    Zhao, Hailong; Dong, Ye; Zhou, Haijing; Zou, Wenkang; Wang, Qiang

    2016-10-01

    Cubic region (34cm × 34cm × 18cm) including the double post-hole convolute (DPHC) structure was chosen to perform a series of fully 3D PIC simulations using NEPTUNE3D codes, massive data ( 200GB) could be acquired and solved in less than 5 hours. Cold-chamber tests were performed during which only cathode electron emission was considered without temperature rise or ion emission, current loss efficiency was estimated by comparisons between output magnetic field profiles with or without electron emission. PIC simulation results showed three stages of current transforming process with election emission in DPHC structure, the maximum ( 20%) current loss was 437kA at 15ns, while only 0.46% 0.48% was lost when driving current reached its peak. DPHC structure proved valuable functions during energy transform process in PTS facility, and NEPTUNE3D provided tools to explore this sophisticated physics. Project supported by the National Natural Science Foundation of China, Grant No. 11571293, 11505172.

  2. Effect of Damping and Yielding on the Seismic Response of 3D Steel Buildings with PMRF

    PubMed Central

    Haldar, Achintya; Rodelo-López, Ramon Eduardo; Bojórquez, Eden

    2014-01-01

    The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions. PMID:25097892

  3. 3D geometry of the strain-field at transform plate boundaries: Implications for seismic rupture

    SciTech Connect

    Bodin, P.; Bilham, R. |

    1994-11-01

    We examine the amplitude and distribution of slip on vertical frictionless faults in the zone of concentrated shear strain that is characteristic of transform plate boundaries. We study both a 2D and a 3D approximation to this strain field. Mean displacements on ruptures within the zone of concentrated shear strain are proportional to the shear strain at failure when they are short, and are limited by plate displacements since the last major earthquake when they are long. The transition between these two behaviors occurs when the length of the dislocation approaches twice the thickness of the seismogenic crust, approximately the breadth of the zone of concentrated shear strain observed geodetically at transform plate boundaries. This result explains the observed non-linear scaling relation between seismic moment and rupture length. A geometrical consequence of the 3D model, in which the strain-field tapers downward, is that moderate earthquakes with rupture lengths similar to the thickness of the crust tend to slip more at depth than near the surface. Seismic moments estimated from surface slip in moderate earthquakes (M less than or equal to 7) will thus be underestimated. Shallow creep, if its along-strike dimension is extensive, can reduce a surface slip deficit that would otherwise develop on faults on which M less than 7 events are typical. In the absence of surface creep or other forms of off-fault deformation great earthquakes may be necessary features of transform boundaries with downward-tapering strain-fields.

  4. Effect of damping and yielding on the seismic response of 3D steel buildings with PMRF.

    PubMed

    Reyes-Salazar, Alfredo; Haldar, Achintya; Rodelo-López, Ramon Eduardo; Bojórquez, Eden

    2014-01-01

    The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions.

  5. Fore-arc seafloor unconformities and geology: Insight from 3-D seismic geomorphology analysis, Peru

    NASA Astrophysics Data System (ADS)

    Calvès, Gérôme; Auguy, Constance; de Lavaissière, Léopold; Brusset, Stéphane; Calderon, Ysabel; Baby, Patrice

    2017-08-01

    New 3-D seismic data collected over 4870 km2 in the 3°45'S-12°30'S Peruvian segment of the East Pacific subduction system image seafloor erosional surfaces that can be mapped across the fore-arc basins. Fore-arc basins experience various stresses, from their base where basal tectonic erosion acts to the seafloor which is influenced by aerial, shallow, and deep water currents driven by waves or thermohaline oceanic currents. Previously there has been little interest in stresses on the upper layer and there is a lack of documentation of unconformities and the erosive processes in certain bathymetric domains in fore-arc basins. We address this with the study of examples sourced from 3-D seismic reflection surveys of the seafloor offshore Peru. Unconformities occur in two distinctive bathymetric domains associated with the continental shelf and the upper slope of the margin. Identification and characterization of unconformity surfaces yield estimates of the amount of erosion at the modern seafloor that range from 18 to 100%. Regional physical oceanography allows us to calibrate potential candidates for these two distinctive domains. The first control on erosion is the dynamics of deep to intermediate oceanic currents related to the Humboldt-Peru Chile water masses, while the second is wave action in the shallower erosional surfaces. This study illustrates the unseen landscape of the fore-arc basins of South America and helps to highlight the importance of erosive surficial processes in subduction landscapes.

  6. Micromagnetic investigation of low-symmetry 3D particles

    NASA Astrophysics Data System (ADS)

    Blachowicz, T.; Ehrmann, A.

    2017-02-01

    Investigating the anisotropies of magnetic nanoparticles is crucial for further development of magnetic data storage media, MRAM, magnetic logical circuits, or magnetic quantum cellular automata. Former theoretical and experimental examinations have revealed the possibility to gain highly symmetric nanoparticles with increased numbers of magnetic states per storage element. In a recent project, we have investigated low-symmetry T-shaped 2D and 3D particles from iron using the micromagnetic simulation software MAGPAR which is based on solving the Landau-Lifshitz-Gilbert (LLG) equation of motion for a mesh built from tetrahedral finite elements. To examine the influence of the reduced symmetry, simulations were performed on the 3D double-T particle with the field applied in different directions in the x-y base plane, ranging from 0 to 180° in 5° steps. Additionally, the external magnetic field was rotated laterally under different angles with respect to the x-y plane, i.e. 5°, 22.5°, and 45°. Similar simulations were executed for the 2D single-T particle. Our results show the strong impact of the shape anisotropy and the respective possibility to tailor magnetic anisotropies according to the desired behaviour by modifying the nanoparticles’ form.

  7. New insights into the earliest Quaternary environments in the Central North Sea from 3D seismic

    NASA Astrophysics Data System (ADS)

    Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

    2014-05-01

    In the past the transition between an unconformable surface in the south to a conformable horizon towards the north has made identification and mapping the base-Quaternary in the central North Sea difficult (Sejrup et al 1991; Gatliff et al 1994). However recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) has allowed greater confidence in the correlation to the region 3D seismic datasets and thus has allowed the base-Quaternary to be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The revised base-Quaternary surface reaches a depth of 1248 ms TWT with an elongate basin shape which is significantly deeper than the traditionally mapped surface. Using RMS amplitudes and other seismic attributes the revised base-Quaternary has been investigated along the horizon and in time slice to interpret the environments of the earliest Quaternary prior to the onset of glaciation. Combined with analysis of aligned elongate furrows over 10 km long, 100 m wide and 100 m deep suggest a deep marine environment in an almost enclosed basin with persistent strong NW-SE bottom currents in the deepest parts. Pockmarks were formed by the escape of shallow gas on the sides of a small delta in the eastern part of the basin. The progradation of large deltas from both the north and south into the basin make up the majority of the deposition of sediment into the basin. Key Words: base-Quaternary; seismic interpretation; paleoenvironments References: Gatliff, R.W, Richards, P.C, Smith, K, Graham, C.C, McCormac, M, Smith, N.J.P, Long, D, Cameron, T.D.J, Evans, D, Stevenson, A.G, Bulat, J, Ritchie, J.D, (1994) 'United Kingdom offshore regional

  8. Hydrocarbon Seeps Formations: a Study Using 3-D Seismic Attributes in Combination with Satellite Data

    NASA Astrophysics Data System (ADS)

    Garcia-Pineda, O. G.; MacDonald, I. R.; Shedd, W.

    2011-12-01

    Analyzing the magnitude of oil discharges from natural hydrocarbon seeps is important in improving our understanding of carbon contribution as oil migrates from deeper sediments to the water column, and then eventually to the atmosphere. Liquid hydrocarbon seepage in the deep water of the Gulf of Mexico (GOM) is associated with deep cutting faults, associated with vertical salt movement, that provide conduits for the upward migration of oil and gas. Seeps transform surface geology and generate prominent geophysical targets that can be identified on 3-D seismic data as seafloor amplitude anomalies maps that correlate with the underlying deep fault systems. Using 3D seismic data, detailed mapping of the northern GOM has identified more than 21,000 geophysical anomalies across the basin. In addition to seismic data, Synthetic Aperture Radar (SAR) images have proven to be a reliable tool for localizing natural seepage of oil. We used a Texture Classifier Neural Network Algorithm (TCNNA) to process more than 1200 SAR images collected over the GOM. We quantified more than 900 individual seep formations distributed along the continental shelf and in deep water. Comparison of the geophysical anomalies with the SAR oil slick targets shows good general agreement between the distributions of the two indicators. However, there are far fewer active oil slicks than geophysical anomalies, most of which are probably associated with gas seepage. By examining several sites where the location of active venting can be determined by submersibles observations, we found that the active oily vents are often spatially offset from the most intense geophysical targets (i.e. GC600, GC767, GC204, etc). In addition to the displacement of the oil by deep sea currents, we propose that during the 100K years of activity, the location of the vents on the seafloor probably migrate as carbonate cementation reduces the permeability of the upper sediment. Many of the geophysical targets may represent

  9. 3D seismic Interpretation of Methane-Hydrate-Concentrated Zone Offshore Japan -Noto Sado area-

    NASA Astrophysics Data System (ADS)

    Tanaka, M.; Fujii, T.; Kobayashi, T.; Kotera, T.

    2016-12-01

    JOGMEC, as a member of research group for resources assessment of Research Consortium for Methane Hydrate Resources in Japan (MH21), has been conducting resources assessment of methane hydrate (MH) offshore surrounding Japan. This study aims to assess the distribution of the bottom simulating reflector (BSR) and methane hydrate concentrated zones (MHCZ) offshore Japan. In terms of resources assessment, it is important that MH concentrated in pore-filling sand . The interpretation of 3-D seismic data acquired by geophysical vessel `Shigen', which is owned by Agency for Natural Resources and Energy, were carried out. We interpreted the distribution of MHCZ in Noto Toho and Sado Seiho areas, which are located in the southwest Sado Island, using high density velocity analysis and channel analysis. The characteristic of 3-D seismic data in this study area showed several folds and faults which does not show the large displacement. The BSR was very visible continuously. Clear velocity contrast in the boundary between above and below of BSR, and the high velocity anomaly above BSR were confirmed in the high density velocity analysis profile. MHs were assumed to exist in sand heterogeneously because the velocity distribution in the extracted zones is inhomogeneous. In the results of geomorphological analysis, channel deposits and mid submarine fan deposits, which are located above BSR, were presumed sandy sediment. As above, even the area has not been drilled, the extraction of MHCZ can be conducted by the interpretation of the seismic data, the result of the high density velocity analysis, and the distribution of sand by geomorphological analysis. These results will be useful for the plan of the future drilling programme.

  10. 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.

  11. 3D absolute hypocentral determination - 13 years of seismicity in Ecuadorian subduction zone

    NASA Astrophysics Data System (ADS)

    Font, Yvonne; Segovia, Monica; Theunissen, Thomas

    2010-05-01

    In Ecuador, the Nazca plate is subducting beneath the North Andean Block. This subduction triggered, during the last century, 4 major earthquakes of magnitude greater than 7.7. Between 1994 and 2007, the Geophysical Institute (Escuela National Politecnica, Quito) recorded about 40 000 events in whole Ecuador ranging from Mb 1.5 to 6.9. Unfortunately, the local network shows great density discrepancy between the Coastal and Andean regions where numerous stations were installed to survey volcanic activity. Consequently, seismicity in and around the interplate seismogenic zone - producer of the most destructive earthquakes and tsunamis - is not well constrained. This study aims to improve the location of 13 years seismicity occurred during an interseismic period in order to better localize the seismic deformation and gaps. The first step consists in the construction of a 3D "georealistic" velocity model. Because local tomography cannot provide satisfactory model, we combined all local crustal/lithospheric information on the geometry and velocity properties of different geological units. Those information cover the oceanic Nazca plate and sedimentary coverture the subducting plate dip angle; the North Andean Block margin composed of accreted oceanic plateaus (the Moho depth is approximated using gravity modeling); the metamorphic volcanic chain (oceanic nature for the occidental cordillera and inter-andean valley, continental one for the oriental cordillera); The continental Guyana shield and sedimentary basins. The resulting 3D velocity model extends from 2°N to 6.5°S and 277°E to 283°E and reaches a depth of 300 km. It is discretized in constant velocity blocks of 12 x 12 x 3 km in x, y and z, respectively. The second step consists in selecting an adequate sub-set of seismic stations in order to correct the effect of station density disequilibrium between coastal and volcanic regions. Consequently, we only keep the most representative volcanic stations in terms

  12. Testing & Validating: 3D Seismic Travel Time Tomography (Detailed Shallow Subsurface Imaging)

    NASA Astrophysics Data System (ADS)

    Marti, David; Marzan, Ignacio; Alvarez-Marron, Joaquina; Carbonell, Ramon

    2016-04-01

    A detailed full 3 dimensional P wave seismic velocity model was constrained by a high-resolution seismic tomography experiment. A regular and dense grid of shots and receivers was use to image a 500x500x200 m volume of the shallow subsurface. 10 GEODE's resulting in a 240 channels recording system and a 250 kg weight drop were used for the acquisition. The recording geometry consisted in 10x20m geophone grid spacing, and a 20x20 m stagered source spacing. A total of 1200 receivers and 676 source points. The study area is located within the Iberian Meseta, in Villar de Cañas (Cuenca, Spain). The lithological/geological target consisted in a Neogen sedimentary sequence formed from bottom to top by a transition from gyspum to silstones. The main objectives consisted in resolving the underground structure: contacts/discontinuities; constrain the 3D geometry of the lithology (possible cavities, faults/fractures). These targets were achieved by mapping the 3D distribution of the physical properties (P-wave velocity). The regularly space dense acquisition grid forced to acquire the survey in different stages and with a variety of weather conditions. Therefore, a careful quality control was required. More than a half million first arrivals were inverted to provide a 3D Vp velocity model that reached depths of 120 m in the areas with the highest ray coverage. An extended borehole campaign, that included borehole geophysical measurements in some wells provided unique tight constraints on the lithology an a validation scheme for the tomographic results. The final image reveals a laterally variable structure consisting of four different lithological units. In this methodological validation test travel-time tomography features a high capacity of imaging in detail the lithological contrasts for complex structures located at very shallow depths.

  13. Thermographic investigations of metal inclusions in 3D printed samples

    NASA Astrophysics Data System (ADS)

    Oswald-Tranta, Beata; Schmidt, Roland; Tuschl, Christoph

    2017-05-01

    Subsurface defects can be well detected by flash thermography evaluating the temperature response at the sample surface. In many cases flat bottom holes or air inclusions are investigated as typical defects. In contrast, in the current paper the main emphasis is placed on metal inclusions hidden in an insulator material. As the thermal effusivity of the metal is significantly higher than of the base material, the temperature decreases quicker above such a defect. Thermal quadrupole calculations and finite element simulations have been used to investigate more closely these temperature signals. Additionally, 3D printed samples have been created, where in the plastic material different metal plates, as steel, aluminum and copper have been introduced. The measurement results on these samples show very good agreement with theoretically calculated curves.

  14. Analysis of Paleokarst Sinkholes in the Arkoma Basin using 3-D Seismic

    NASA Astrophysics Data System (ADS)

    Kumbalek, Michael

    Paleokarst features are important to understand, both with regards to research geologists and to the petroleum industry. In terms of geology, understanding paleokarst features can yield more information about the depositional and surface environments of past times, and how diagenetic alteration affected the environment during the formation of karst features. In the petroleum industry, paleokarst features can have positive or negative consequence resulting in a potential reservoir with enhanced porosity due to the paleokarst features, or as a geo-hazard to prepare for or avoid when drilling. Inspired by issues faced when drilling in the Ft. Worth basin, this study utilizes multiple 3-D seismic surveys and subsurface well control to map paleokarsts within the Viola Limestone in the Arkoma Basin. Calculated seismic attribute volumes used to identify paleokarst sinkholes within the Viola Group include coherency and curvature attributes. ImageJ software was used to aid in counting and measuring paleokarst sinkholes identified using seismic mapping, coherency, and curvature attribute volumes. In addition to mapping, a cumulative distribution plot was produced from the diameters of the seismically mapped paleokarst sinkholes, allowing for an estimate to be made as to what the total amount of paleokarst sinkholes are within the study area. The methods detailed in this study proved to be effective in mapping and analyzing paleokarst sinkholes within the Viola Group. The paleokarst sinkholes mapped were determined to have been formed on the outer edge of the Southern Oklahoma aulacogen, as a result of the Sylvan/Viola unconformity. In addition to this, it has been determined that these paleokarst sinkholes are linked in formation to visually similar paleokarst sinkholes located in the Ellenburger Group in the Fort Worth Basin.

  15. Seismic shaking scenarios in realistic 3D crustal model of Northern Italy

    NASA Astrophysics Data System (ADS)

    Molinari, I.; Morelli, A.; Basini, P.; Berbellini, A.

    2013-12-01

    Simulation of seismic wave propagation in realistic crustal structures is a fundamental tool to evaluate earthquake-generated ground shaking and assess seismic hazard. Current-generation numerical codes, and modern HPC infrastructures, allow for realistic simulations in complex 3D geologic structures. We apply such methodology to the Po Plain in Northern Italy -- a region with relatively rare earthquakes but having large property and industrial exposure, as it became clear during the two M~6 events of May 20-29, 2012. Historical seismicity is well known in this region, with maximum magnitudes estimates reaching M~7, and wave field amplitudes may be significantly amplified by the presence of the very thick sedimentary basin. Our goal is to produce estimates of expected ground shaking in Northern Italy through detailed deterministic simulations of ground motion due to expected earthquakes. We defined a three-dimensional model of the earth's crust using geo-statistical tools to merge the abundant information existing in the form of borehole data and seismic reflection profiles that had been shot in the '70s and the '80s for hydrocarbon exploration. Such information, that has been used by geologists to infer the deep structural setup, had never been merged to build a 3D model to be used for seismological simulations. We implement the model in SPECFEM3D_Cartesian and a hexahedral mesh with elements of ~2km, that allows us to simulate waves with minimum period of ~2 seconds. The model has then been optimized through comparison between simulated and recorded seismograms for the ~20 moderate-magnitude events (Mw > 4.5) that have been instrumentally recorded in the last 15 years. Realistic simulations in the frequency band of most common engineering relevance -- say, ~1 Hz -- at such a large scale would require an extremely detailed structural model, currently not available, and prohibitive computational resources. However, an interest is growing in longer period ground

  16. High-Resolution 3D Seismic Imaging of Fluid Flow Anomalies in the Southwest Barents Sea

    NASA Astrophysics Data System (ADS)

    Planke, S.; Eriksen, F. N.; Eriksen, O. K.; Assad, M.; Stokke, H. H.

    2014-12-01

    Fluid flow features imaged as gas flares in the water column, pockmarks and mud volcanoes on the seabed, and high-amplitude cross-cutting reflections and bright spots in the sub-surface are abundant in the SW Barents Sea offshore northern Norway. This region is covered by extensive conventional 2D and 3D deep penetration seismic reflection data and multibeam bathymetry. High-resolution 3D P-Cable seismic data have been acquired in the SW Barents Sea over the past few years to image the uppermost ca. 500 m of the sub-surface. The P-Cable system consist of 12 to 16 short streamers (25 m) that are towed on a cross-cable perpendicular to the vessel's steaming direction. This configuration allows for acquisition of seismic data with high trace density, typically with 6 m in-line separation. The vertical resolution is a good as 1-2 m using conventional site survey air gun configurations. The sedimentary succession in the SW Barents Sea consists of upper Paleozoic evaporites overlaid by Mesozoic and Cenozoic clastic sediments. There are several organic-rich intervals in the sequence, including Paleozoic coals and Triassic and Jurassic marine source rocks that are locally in the oil or gas maturation windows. Glacial erosion has locally removed kilometer thick Cenozoic and Mesozoic successions, leaving the Mesozoic and Paleozoic strata in shallow sub-surface. The new high-resolution 3D surveys have targeted shallow fluid anomalies in the subsurface. These are imaged as high-amplitude reflections in fault blocks and structural highs, locally cross-cutting well-defined Mesozoic reflections. Commonly, disturbed reflections are present in overlying sequences, or high-amplitude reflections are imaged in the glacial overburden sediments. Locally, hundreds of pockmarks are imaged by the seafloor reflection. The deep cross-cutting reflections are interpreted as hydrocarbon accumulations that locally migrate towards the surface. The fluids are stored in shallow gas pockets or

  17. Real time 3D scanner: investigations and results

    NASA Astrophysics Data System (ADS)

    Nouri, Taoufik; Pflug, Leopold

    1993-12-01

    This article presents a concept of reconstruction of 3-D objects using non-invasive and touch loss techniques. The principle of this method is to display parallel interference optical fringes on an object and then to record the object under two angles of view. According to an appropriated treatment one reconstructs the 3-D object even when the object has no symmetrical plan. The 3-D surface data is available immediately in digital form for computer- visualization and for analysis software tools. The optical set-up for recording the 3-D object, the 3-D data extraction and treatment, as well as the reconstruction of the 3-D object are reported and commented on. This application is dedicated for reconstructive/cosmetic surgery, CAD, animation and research purposes.

  18. UCVM: From Supercomputers to Laptops, Querying and Visualizing 3D Seismic Velocity Models

    NASA Astrophysics Data System (ADS)

    Gill, D.; Small, P.; Maechling, P. J.; Jordan, T. H.; Shaw, J. H.; Plesch, A.; Lee, E. J.; Chen, P.; Goulet, C. A.; Taborda, R.; Olsen, K. B.; Callaghan, S.

    2016-12-01

    Three-dimensional (3D) seismic velocity models provide the underlying material properties and structural geometry needed to conduct earthquake ground motion simulations. The Southern California Earthquake Center (SCEC) has developed the Unified Community Velocity Model (UCVM) software package in order to facilitate access to these models. This unique framework provides a comprehensive set of tools for querying and visualizing models, and for generating discretized versions of the models that can be readily used for simulations. We present here UCVM version 16.12.0, which was re-written from scratch in Python 3 in response to an increasing base of users and their needs. This version improves installation and usability. UCVM uses HDF5, MPI4Py, and other open source software to deliver models on many platforms, from a desktop Mac to a large supercomputer. Version v16.12.0 supports the southern California velocity models: CVM-S4, CVM-H 15.1.0, and CVM-S4.26. It also supports the latest model built for central California (CCA). The software framework makes it easy to extract material properties (seismic P and S velocities, and density) for specific data points by providing a common interface through which researchers can query seismic velocity models for a given location and depth. UCVM has a built-in digital elevation model to facilitate queries by depth or elevation. It includes visualization tools that can generate 2D cross-sections, horizontal slices, and basin depth maps; and we recently added the capability to generate VS30 maps and 1D depth profiles as well. The latest version of UCVM includes a new installation script designed to facilitate out-of-the-box plug-and-play usage by all types of users. The script will automatically download all the dependencies and components of UCVM. Since the platform is written in Python, users can import UCVM functions, modules, and classes for use in their own software. UCVM is currently being used to generate 3D regular grids

  19. 3D time-lapse seismic traveltime tomography for detecting near surface velocity variations: a case study from the Ketzin CO2 storage pilot site

    NASA Astrophysics Data System (ADS)

    Zhang, Fengjiao; Juhlin, Christopher; Huang, Fei; Lüth, Stefan

    2016-04-01

    Time-lapse seismic methods are an important tool for monitoring CO2 migration and storage in geological formations. Near surface variations are one of the major problems which may introduce time-lapse noise in the application of land based seismic monitoring. Conventional reflection seismic methods have difficulties in imaging near surface structures (10-30 m depth) due to the limitation of the methods themselves. Traveltime tomography is a commonly used method to reconstruct the subsurface velocity model. It can often provide extra information on near surface structures which is difficult to obtain by the conventional reflection seismic method. In this study, we apply traveltime tomography to 3D time-lapse seismic data sets acquired from at the Ketzin CO2 storage site. We also test different inversion strategies for traveltime tomography to investigate which one is more suitable for this case study. The results show good correlation with near surface variations obtained by other studies.

  20. On the spatial distribution of seismicity and the 3D tectonic stress field in western Greece

    NASA Astrophysics Data System (ADS)

    Kassaras, Ioannis; Kapetanidis, Vasilis; Karakonstantis, Andreas

    2016-10-01

    We analyzed a large number of focal mechanisms and relocated earthquake hypocenters to investigate the geodynamics of western Greece, the most seismically active part of the Aegean plate-boundary zone. This region was seismically activated multiple times during the last decade, providing a large amount of enhanced quality new information that was obtained by the Hellenic Unified Seismological Network (HUSN). Relocated seismicity using a double-difference method appears to be concentrated above ∼35 km depth, exhibiting spatial continuity along the convergence boundary and being clustered elsewhere. Earthquakes are confined within the accreted sediments escarpment of the down-going African plate against the un-deformed Eurasian hinterland. The data arrangement shows that Pindos constitutes a seismic boundary along which large stress heterogeneities occur. In Cephalonia no seismicity is found to be related with the offshore Cephalonia Transform Fault (CTF). Onshore, Nsbnd S crustal extension dominates, while in central and south Peloponnesus the stress field appears rotated by 90°. Shearing-stress obliquity by 30° is indicated along the major strike-slip faults, consistent with clockwise crustal rotation. Within the lower crust, the stress field appears affected by plate kinematics and distributed deformation of the lower crust and upper mantle, which guide the regional geodynamics.

  1. Structure and evolution of the Kerkennah high (eastern Tunisia) based on 3D seismic

    NASA Astrophysics Data System (ADS)

    Mastouri, R.; Marchant, R.; Jaboyedoff, M.; Bouaziz, S.; Marillier, F.

    2012-04-01

    The Kerkennah high is located in the near shore region of eastern Tunisia. It extends from the Jeffara-Djerba high in the south to the Medina-Lampadusa plateau in the north and encompasses the Kerkennah islands. A detailed knowledge of the tectonic processes affecting this area is essential in order to attempt to fully understand the controls of fracture development. In the Kerkennah islands, the marine and continental Plio-Quaternary series crop out affected by mojor faults trending NW-SE. In the subsurface, the stratigraphic section consists of an almost complete Mesozoic-Cenozoic sequence interbedded by major unconformities. The present-day Kerkennah high overlies an older basement lineament which may have been created during the Mesozoïc and Cenozoïc tectonic events. The 3D seismic reflection interpretation provides a good opportunity to analyze the subsurface images better than 2D seismic reflection. In fact, the geometrical characteristics of the different fault systems associated and the basin individualization are well established using 3D technique. In this paper we present, the NW-SE and NE-SW trending extensional faults, active during the Cenozoic and Quaternary in different phases. These faults form a series of grabens that vary in length from a few to several hundred kilometers. The structuring of NE-SW en echelon faults indicates a strike slip type of bordering faults. In this work, we focus on the evolution of the tectonic structures in the basin, in particular during the Eocene to Early Pliocene extension phase. The geodynamic evolution of Mesozoïc and Cenozoïc basins in the studied areas was dominated by several tectonic stages corresponding to a specific structural development in extension as well as in compression. This evolution will be discussed in the frame of major tectonic event that originated the opening of the Tethyan Ocean and the Mediterranean closing.

  2. Refining seismic parameters in low seismicity areas by 3D trenching: The Alhama de Murcia fault, SE Iberia

    NASA Astrophysics Data System (ADS)

    Ferrater, Marta; Ortuño, Maria; Masana, Eulàlia; Pallàs, Raimon; Perea, Hector; Baize, Stephane; García-Meléndez, Eduardo; Martínez-Díaz, José J.; Echeverria, Anna; Rockwell, Thomas K.; Sharp, Warren D.; Medialdea, Alicia; Rhodes, Edward J.

    2016-06-01

    Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 ± 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 ± 1.1 ka and 21.9-22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault. The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 5.3 and 6.3 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas.

  3. Initialising reservoir models for history matching using pre-production 3D seismic data: constraining methods and uncertainties

    NASA Astrophysics Data System (ADS)

    Niri, Mohammad Emami; Lumley, David E.

    2017-10-01

    Integration of 3D and time-lapse 4D seismic data into reservoir modelling and history matching processes poses a significant challenge due to the frequent mismatch between the initial reservoir model, the true reservoir geology, and the pre-production (baseline) seismic data. A fundamental step of a reservoir characterisation and performance study is the preconditioning of the initial reservoir model to equally honour both the geological knowledge and seismic data. In this paper we analyse the issues that have a significant impact on the (mis)match of the initial reservoir model with well logs and inverted 3D seismic data. These issues include the constraining methods for reservoir lithofacies modelling, the sensitivity of the results to the presence of realistic resolution and noise in the seismic data, the geostatistical modelling parameters, and the uncertainties associated with quantitative incorporation of inverted seismic data in reservoir lithofacies modelling. We demonstrate that in a geostatistical lithofacies simulation process, seismic constraining methods based on seismic litho-probability curves and seismic litho-probability cubes yield the best match to the reference model, even when realistic resolution and noise is included in the dataset. In addition, our analyses show that quantitative incorporation of inverted 3D seismic data in static reservoir modelling carries a range of uncertainties and should be cautiously applied in order to minimise the risk of misinterpretation. These uncertainties are due to the limited vertical resolution of the seismic data compared to the scale of the geological heterogeneities, the fundamental instability of the inverse problem, and the non-unique elastic properties of different lithofacies types.

  4. Enhancement of discontinuities in seismic 3-D images using a Java estimation library

    NASA Astrophysics Data System (ADS)

    Schwab, Matthias

    Seismic images are difficult to interpret. The nature of the seismic experiment and the ever present sedimentary layering of the subsurface result in oscillatory and complex 3-D seismic images In principle, computer programs can enhance geologically significant image features, such as faults, erosional surfaces, and salt boundaries. Standard edge enhancement, however, fails to compute useful seismic discontinuity maps. The correlation between an image region and its best-fitting local plane wave generates clear and discriminating maps for a wide range of images. A third approach, prediction-error filtering, yields detailed fault maps for images with sharp faults. For images with rather smooth fault zones, prediction error unfortunately fails. This dissertation's discontinuity computations are the first comprehensive application of a new innovative Java estimation library: Jest (Java for estimation). Jest comprises a general and extendible library for numerical optimization for science and engineering, Jam (Java and mathematics), and a particular extension of that framework for seismic image processing, Jag (Java and geophysics). Jest successfully separates optimization and application software. To ensure the compatibility of solver and application, Jest is built around a set of simple interfaces that define method invocations for the fundamental mathematical objects of numerical optimization, such as vectors, vector spaces, operators, and solvers. Jest's solvers are implemented in terms of these mathematical objects and, consequently, possess the generality of the original abstract mathematical algorithm. Finally, the dissertation is a reproducible electronic document, a simple software filing system that organizes, preserves, and potentially transfers the technology of any computational scientific research project. The document's central makefile offers readers four standard commands: burn removes the document's result figures, build recomputes them, view displays

  5. Vectorial seismic modeling for 3D objects by the classical solution

    NASA Astrophysics Data System (ADS)

    Ávila-Carrera, R.; Sánchez-Sesma, F. J.; Rodríguez-Castellanos, A.; Ortiz-Alemán, C.

    2010-09-01

    The analytic benchmark solution for the scattering and diffraction of elastic P- and S-waves by a single spherical obstacle is presented in a condensed format. Our aim is divulge to the scientific community this not widely known classical solution to construct a direct seismic model for 3D objects. Some of the benchmark papers are frequently plagued by misprints and none offers results on the transient response. The treatment of the vectorial case appears to be insipient in the literature. The classical solution is a superposition of incident and diffracted fields. Plane P- or S-waves are assumed. They are expressed as expansions of spherical wave functions which are tested against exact results. The diffracted field by the obstacle is calculated from the analytical enforcing of boundary conditions at the scatterer-matrix interface. The spherical obstacle is a cavity, an elastic inclusion or a fluid-filled body. A complete set of wave functions is used in terms of Bessel and Hankel radial functions. Legendre and trigonometric functions are used for the angular coordinates. In order to provide information to calibrate and approximate the seismic modeling for real objects, results are shown in time and frequency domains. Diffracted displacements amplitudes versus normalized frequency and radiation patterns for various scatterer-matrix properties are reported. To study propagation features that may be useful to geophysicists and engineers, synthetic seismograms for some relevant cases are computed.

  6. Surface amplitude data: 3D-seismic for interpretation of sea floor geology (Louisiana Slope)

    SciTech Connect

    Roberts, H.H.

    1996-09-01

    Proliferation of 3D-seismic in support of hydrocarbon exploration/production has created new data for improved interpretation of sea floor and shallow subsurface geology. Processing of digital seismic data to enhance amplitude anomalies produces information for improved assessment of geohazards and identification of sensitive benthic communities protected by environmental regulations. Coupled with high resolution acoustic data and direct observation/sampling using a manned research submersible, surface amplitude maps add critical interpretive information for identification of sea floor features. Non-reflective zones (acoustic wipeouts) are associated with many slope features. Mud diapirs, mud mounds, mud volcanoes, gas-changed sediments, gas hydrates, slump deposits, carbonate hardgrounds, and various types of carbonate mounds are all features that exhibit this common response on high resolution seismic profiles. Amplitude data help make specific identifications. Since 1988, submersible data from mid-to-upper slope features (Garden Banks, Green Canyon, and Mississippi Canyon lease block areas) have been analyzed with conventional high resolution acoustic data and 313-amplitude extraction maps. Areas of rapid venting of sediment and hydrocarbon-charged formation fluids are clearly distinguishable from mud diapirs and areas of carbonate mounds (slow seepage). Gas hydrates occur as mounds and mounded zones along faults; products of moderate flux rates below (approx.) 500 in water depths. Gas hydrates function as stored trophic resources that support sensitive chemosynthetic communities. Amplitude extraction maps clearly identify these features by a strong low impedance amplitude anomaly. Refinement and {open_quotes}field calibration{close_quotes} of the surface amplitude extraction method may eventually lead to a new standard for evaluating geohazards and sensitive benthic communities.

  7. 3D Euler deconvolution in the New Madrid seismic zone (eastern US)

    NASA Astrophysics Data System (ADS)

    Arroucau, P.; Vlahovic, G.; Powell, C. A.

    2011-12-01

    The seismicity of intraplate continental interiors is one of the most challenging -though a bit overlooked- research topics in seismology. The most famous of those is undoubtedly the New Madrid seismic zone (NMSZ), named after the city of New Madrid, Missouri, that was destroyed by one of the three M>7.0 earthquakes that occurred in central United States during the winter 1811-1812. After two centuries, there is still no consensus about what caused that crisis, how it is related to the current moderate magnitude activity of that region, and how likely it is that similarly large events will occur again in a near future in the NMSZ or in its vicinity. As often in such geodynamic settings, a key question is the role of structural reactivation in the current stress field. As modern earthquakes of the NMSZ mostly occur in the Precambrian basement, below the Mississippi embayment sedimentary cover and at such depths that no deformation is observed at the surface, almost no direct observation is available about faults segments that would be responsible for that seismicity. Yet the activity of the NMSZ is known to coincide with a Precambrian failed rift, the Reelfoot rift, whose geometry is mostly inferred from potential field data. In this work, we apply 3D Euler deconvolution to the total magnetic intensity field of the NMSZ. Euler deconvolution is a technique commonly used in exploration geophysics to determine the depth of magnetic sources and more generally to produce depth-to-basement maps and image deep structures buried beneath non-magnetic sedimentary cover. We obtain basement topography maps that we compare with previously published maps and with the earthquake distribution in the NMSZ.

  8. Distribution of free gas and 3D mirror image structures beneath Sevastopol mud volcano, Black sea, from 3D high resolution wide-angle seismic data

    NASA Astrophysics Data System (ADS)

    Krabbenhoeft, A.; Papenberg, C. A.; Klaeschen, D.; Bialas, J.

    2016-12-01

    The goal of this study is to image the sub-seafloor structure beneath the Sevastopol mud volcano (SMV), Sorokin Trough, SE of the Crimean peninsula, Black Sea. The focus lies on structures of/within the feeder channel, the distribution of gas and gas hydrates, and their relation to fluid migration zones in sediments. This study concentrates on a 3D high resolution seismic grid (7 km x 2.5 km) recorded with 13 ocean bottom stations (OBS). The 3D nature of the experiment results from the geometry of 68 densely spaced (25/50 m) profiles, as well as the cubical configuration of the densely spaced receivers on the seafloor ( 300 m station spacing). The seismic profiles are typically longer than 6 km which results in large offsets for the reflections of the OBS. This enables the study of the seismic velocities of the sub-seafloor sediments and additionally large offset incident analysis.The 3D Kirchhoff mirror image time migration, applied to all OBS sections including all shots from all profiles, leads to a spatial image of the sub-seafloor. Here, the migration was applied with the velocity distribution of 1.49 km/s in the water column, 1.5 km/s below the seafloor (bsf) increasing to 2 km/s for the deeper sediments at 2 s bsf. Acoustic blanking occurs beneath the south-easterly located OBS and is associated with the feeder channel of the mud volcano. There, gas from depth can vertically migrate to the seafloor and on its way to the surface horizontally distribute patchily within sediment layers. High amplitude reflections are not observed as continuous reflections, but in a patchy distribution. They are associated with accumulations of gas. Also structures exist within the feeder channel of the SMV.3D mirror imaging proves to be a good tool to seismically image structures compared with 2D streamer seismics, especially steep dipping reflectors and structures which are otherwise obscured by signal scattering, i.e structures associated with fluid migration paths.

  9. 3-D seismic redevelopment of Louisiana`s Tuscaloosa trend, Port Hudson field case history

    SciTech Connect

    Story, C.

    1996-09-01

    The Port Hudson field is a salt-cored anticline which produces from the Cretaceous Tuscaloosa Formation 15 miles north of Baton Rouge, Louisiana. Approximately 480 BCF and 45 MMBO have been produced in the last 18 years from depths between 15,400 and 17,400 feet. An extensive grid of 2-D seismic was acquired over the field during the 1970`s and early 1980`s. In October of 1994 interpretation of a new 60 sq. mile 3-D dataset was completed. The Amoco Tuscaloosa asset group to date has defined 9 new prospect locations based primarily on the highly detailed structural and stratigraphic mapping possible with the new dataset. Seven of the locations have been drilled with a 100 percent success ratio and added new proven gross reserves of 200 to 300 BCFE. The remaining 2 locations will be drilled by the spring of 1996 and bring the total drilling investment to $50 million. The key learning point to be made with this case history is that the tremendous improvement in imaging with 3-D can lead to entirely new depositional and structural models even in heavily drilled areas.

  10. Modeling the Coast Mountains Batholith, British Columbia, Canada with 3D Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Quinonez, S. M.; Olaya, J. C.; Miller, K. C.; Romero, R.; Velasco, A. A.; Harder, S. H.; Cerda, I.

    2011-12-01

    The Coast Mountains Batholith on the west coast of British Columbia, Canada comprises a series of granitic to tonalitic plutons; where felsic continental crust is generated from the subduction of mafic oceanic crust by partial melting and fractionation, leaving ultra-mafic roots. In July of 2009, a large controlled-source experiment was conducted along a 400km east - west transect from Bella Bella into central British Columbia. Student volunteers from multiple universities deployed 1,800 one-component and 200 three-component geophones plus 2400 Texan data recorders with 200-m spacing intervals and shot spacing at 30-km. The 18-point sources ranged from 160 to 1,000 kg of high explosive. The geoscience component of the NSF-funded Cyber-ShARE project at UTEP focuses on fusing models developed from different data sets to develop 3-D Earth models. Created in 2007, the Cyber-ShARE Center brings together experts in computer science, computational mathematics, education, earth science, and environmental science. We leverage the Cyber-ShARE work to implement an enhanced 3-D finite difference tomography approach for P-wave delays times (Hole, 1992) with a graphical user interface and visualization framework. In particular, to account for model sensitivity to picked P-wave arrival times, we use a model fusion approach (Ochoa et al., 2010) to generate a model with the lowest RMS residual that a combination of a set of Monte Carlo sample models. In order to make the seismic tomography process more interactive at many points, visualizations of model perturbation at each iteration will help to troubleshoot when a model is not converging to highlight where the RMS residual values are the highest to pinpoint where changes need to be made to achieve model convergence. Finally, a model of the upper mantle using 3-D P-wave tomography will be made to determine the location of these ultra-mafic roots.

  11. New 3D seismicity maps using chromo-stereoscopy with two alternative freewares

    NASA Astrophysics Data System (ADS)

    Okamoto, Y.

    2011-12-01

    Seismicity maps play a key role in an introduction of geosciences studies or outreach programs. Various techniques are used in order to show earthquakes in a three dimensional field. To use "chromo-stereoscopy" is our simple and easier-making solution. The Chroma Depth 3D Glasses are employed for this purpose. The glasses consist of two transparent blazed grating films covered with a paper holder and cost a little (1 US$). Looking through these glasses, the colored chart turns into three dimensional perspective due to the mechanism that the color codes make a depth dimension with dispersion. We use two complementary freewares to make maps, the GMT (Generic Mapping Tools, Wessel and Smith.1988) and the POV-Ray (Persistence of Vision Pty. Ltd. 2004). The two softwares have their own advantages; the GMT is specialized for map making with simple scripts, while the POV-Ray produces realistic 3D rendering images with more complicated scripts. The earthquakes are plotted with the rainbow color codes depending on their depths in a black background as printed or PC images. Therefore, the red colored shallow earthquakes are float in front and blue colored ones sink deeper. This effect is so amazing that the students who first wear these glasses are strongly moved and fascinated with this simple mechanism. The data used here are from JMA seismicity catalogue and USGS (ANSS) catalogue. The POV-Ray version needs coastline data, so we got them from the Coastline Extractor (NGDC) web site. Also, the POR-Ray has no function to draw lines in three dimensions, so we had to make some trials for showing them in relief. The main target of our map is "the Wadati-Beniof zone", in which the sub-ducting oceanic plate surface is fringed by deeper earthquakes colored yellow, green to blue. The active volcanic regions such as the Hawaii islands or the active fault regions such as the San Andreas Fault are also effective targets of our method. However, since their shallow complicated seismic

  12. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-05-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  13. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-05-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  14. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N.P. Paulsson

    2005-08-21

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  15. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2003-12-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  16. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  17. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-06-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  18. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N.P Paulsson

    2006-05-05

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  19. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2005-03-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  20. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-12-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  1. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N. P. Paulsson

    2005-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  2. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P Paulsson

    2003-09-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  3. 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

  4. Refining the 3D seismic velocity and attenuation models for Katmai National Park, Alaska

    NASA Astrophysics Data System (ADS)

    Murphy, R. A.; Thurber, C. H.; Prejean, S. G.

    2009-12-01

    We invert data from approximately 4,000 local earthquakes occurring between September 2004 and August 2009 to determine the 3D P-wave velocity and P-wave attenuation structures in the Katmai volcanic region. Arrival information and waveforms for the study come from the Alaska Volcano Observatory’s permanent network of 20 seismometers in the area, which are predominantly single-component, short period instruments. The absolute and relative arrival times are used in a double-difference seismic tomography inversion to solve for an improved velocity model for the main volcanic centers. We use the resulting 3D velocity model to relocate all catalog earthquakes in Katmai between January 1996 and August 2009. Inversions for the quality factor Q are completed using a spectral decay approach to determine source parameters, t*, and site response with a nonlinear inversion. Using the final 3D velocity model to define the ray paths, t* values are then inverted to determine frequency-independent Q models. The final models developed through these inversions reveal a low velocity and low Q zone from the surface to ~7 km depth centered on the volcanic axis and extending ~25 km between Martin and Katmai volcanoes. The relocated hypocenters provide insight into the geometry of seismogenic structures in the area, revealing clustering of events into four distinct zones associated with Martin, Mageik, Trident, and Katmai. While the Martin, Mageik, and Katmai clusters are all at 3-4 km depth, the Trident cluster is slightly deeper at 4-6 km. Many new features are apparent within these clusters, including a strand of earthquakes trending NE-SW between the main Martin and Mageik clusters. Smaller linear features are also visible in the Katmai cluster along with a small migrating swarm which occurred NW of the Katmai caldera during mid-2006. Data from an array of 11 three-component broadband instruments currently deployed in the area between Mageik volcano and Katmai caldera will be

  5. Zonation of North Alex Mud Volcano Highlighted by 3-D Active and Passive Seismic Data

    NASA Astrophysics Data System (ADS)

    Bialas, J.; Lefeldt, M. R.; Klaeschen, D.; Papenberg, C. A.; Brueckmann, W.

    2010-12-01

    The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex (NA) developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A 3-D high-resolution multichannel seismic survey (IFM-GEOMAR P-Cable system) was completed across the mud volcano. 3-D time migration provided a 3-D data cube with a 6.25 m grid. Vertical seismic sections did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. Horizontal amplitude maps (time slices) of indicate recent activity of these faults even up to the seafloor. High gas saturation of the sediments is indicated by inverted reflection events. In the centre the gas front cuts into the seafloor reflection while it dips down with increasing radius. Only with the small grid resolution inward dipping reflections become visible, which form an upward opened concave reflector plane underlying the top gas front. The interpretation assumes an oval lens shaped body (conduit) saturated with gas at the top of the mud volcano. It provides the upper termination of the mud chimney. This separation is further supported by passive seismic observations. Distant earthquakes can stimulate long-period harmonic oscillations in mud volcanoes. Such oscillations are detectable with three

  6. 3D Discontinuous Galerkin elastic seismic wave modeling based upon a grid injection method

    NASA Astrophysics Data System (ADS)

    Monteiller, V.

    2015-12-01

    Full waveform inversion (FWI) is a seismic imaging method that estimates thesub-surface physical properties with a spatial resolution of the order of thewavelength. FWI is generally recast as the iterative optimization of anobjective function that measures the distance between modeled and recordeddata. In the framework of local descent methods, FWI requires to perform atleast two seismic modelings per source and per FWI iteration.Due to the resulting computational burden, applications of elastic FWI have been usuallyrestricted to 2D geometries. Despite the continuous growth of high-performancecomputing facilities, application of 3D elastic FWI to real-scale problemsremain computationally too expensive. To perform elastic seismic modeling with a reasonable amount of time, weconsider a reduced computational domain embedded in a larger background modelin which seismic sources are located. Our aim is to compute repeatedly thefull wavefield in the targeted domain after model alteration, once theincident wavefield has been computed once for all in the background model. Toachieve this goal, we use a grid injection method referred to as the Total-Field/Scattered-Field (TF/SF) technique in theelectromagnetic community. We implemented the Total-Field/Scattered-Field approach in theDiscontinuous Galerkin Finite Element method (DG-FEM) that is used to performmodeling in the local domain. We show how to interface the DG-FEM with any modeling engine (analytical solution, finite difference or finite elements methods) that is suitable for the background simulation. One advantage of the Total-Field/Scattered-Field approach is related to thefact that the scattered wavefield instead of the full wavefield enter thePMLs, hence making more efficient the absorption of the outgoing waves at theouter edges of the computational domain. The domain reduction in which theDG-FEM is applied allows us to use modest computational resources opening theway for high-resolution imaging by full

  7. The 3D crustal structure of Northeastern Tibetan area from seismic tomography

    NASA Astrophysics Data System (ADS)

    Sun, Anhui

    2015-04-01

    The Northeastern Tibetan region is located in the border area of three sub-plates in China, i.e. the Tibetan plateau, North China block and Xinjiang block. Effected simultaneously by the extrusion driven by the India-Eurasia plat collision and the blockage of the Ordos basin, this area has complex geology, strong tectonics activities and suffered from several large historic earthquakes, such as the Haiyuan earthquake (M8.6) in 1920, the Gulang earthquake (M8.0) in 1927. To enhance our understanding of the crustal structure and the interaction between different tectonic blocks of this region, we conduct a three-dimensional (3D) tomographic study by using the arrival time date recorded by regional seismic network. We used 101101 P and 103313 S wave arrival times from 11650 local earthquakes during 1970 to 2013 recorded by 154 permanent seismic stations of the local Seismic Network, installed over five provinces in China, i.e. Gansu, Ningxia, Qinghai, Shanxi, Neimenggu. We first established a 1D primary crustal model from LITHO1.0, an updated crust and lithospheric model of the Earth by weighted averaging. To better performer ray tracing, our inversion involved three discontinuities (including the Moho) with depth variation over the mantle derived from LITHO1.0. Detailed three-dimensional seismic velocity (Vp and Vs) structures of the crust of the Northeastern Tibetan are determined with a horizontal resolution of about 35 km and a depth resolution of 6-20 km. The Poisson's ratio (σ) structure was also estimated after obtained Vp and Vs structures. We detected low-velocity anomalies in the lower crust and relative high-velocity anomalies in the upper crust beneath the Longmenshan faults zone, which are in good agreement with the results of most previous geophysical studies. Our results revealed clear different velocity variation beneath both sides of different tectonic blocks. In addition, we found the correlation between our tomographic result and previous

  8. Constructing a 3D structural block diagram of the Central Basin in Marmara Sea by means of bathymetric and seismic data

    NASA Astrophysics Data System (ADS)

    Demirbağ, Emin; Kurt, Hülya; Düşünür, Doğa; Sarıkavak, Kerim; Çetin, Suna

    2007-12-01

    In this study we made a comparative interpretation of multibeam bathymetric and seismic reflection data with different resolutions and penetration properties collected in the Central Basin of the Marmara Sea. Our main objectives were (i) to investigate and compare the active tectonic deformation observed on the sea bottom and within the uppermost sedimentary layers to that of the deep-seated deformation within the limits of resolution and penetration of the available geophysical data and (ii) to build a three-dimensional (3D) block diagram of the active tectonic and buried features by means of a sliced mapping technique. In this approach, we produced slice maps of the active and buried structural features at selected depths and then combined them to form a 3D structural block diagram. Motivation for our work was to produce a 3D structural diagram to derive a more detailed image of the structural features in the Central Basin where there is no available 3D seismic data. The observations from the bathymetry and seismic data and developed 3D diagram support the presence of a through-going strike-slip fault that forms a rotational depression zone against a right-stepping strike-slip faulting causing a pull-apart basin in the Central Depression zone.

  9. High-Resolution Seismic Images and 3-D Seismic Velocities of the San Andreas Fault Zone at Burro Flats, Southern California

    NASA Astrophysics Data System (ADS)

    Tsai, C.; Catchings, R. D.; Rymer, M. J.; Goldman, M. R.

    2003-12-01

    The southern San Andreas fault (SAF) has produced large earthquakes in the past 1500 yrs. Burro Flats, a basin within the San Bernardino Mountains, is bounded on the southwest by the southern San Andreas fault. Burro Flats has been the site of paleoseismological investigations to determine the slip history of the fault. Additional paleoseismic studies at this location are needed to further resolve the structure and slip history of the SAF. In addition to the main trace of the SAF at Burro Flats, there are splay faults, suggesting a complex geometry for the fault. To better understand the structure of the SAF, we acquired a 3-D, combined seismic reflection/refraction profile centered on the main trace at Burro Flats. The seismic investigation included a 60 m by 70 m rectangular array. Sensors were spaced every 5 m; seismic sources, likewise with a spacing of 5 m, consisted of a combination of down-hole explosives and shallow (approximately 0.3 m) Betsy Seisgun shots. Data were recorded without acquisition filters for 5 s at a 0.5-ms sampling rate. To analyze the data for velocity structure, we used a tomographic inversion procedure to invert first-arrival refractions. Preliminary measurements from shot gathers show that near-surface velocities range between 700 m/s and 1500 m/s. We observe apparent travel-time delays of approximately 7 ms near the main surface trace of the SAF, suggesting that seismic imaging methods may be useful in identifying this and other fault traces. These results will be useful for paleoseismic investigations.

  10. 3D Seismic and Magnetic characterization of the Borax Lake Hydrothermal System in the Alvord Desert, southeastern Oregon.

    NASA Astrophysics Data System (ADS)

    Hess, S.; Bradford, J.; Lyle, M.; Routh, P.; Liberty, L.; Donaldson, P.

    2004-05-01

    As part of an interdisciplinary project aiming to study the link between the physical characteristics of hydrothermal systems and biota that occupy those systems, we are conducting a detailed geophysical characterization of an active hydrothermal system. The Borax Lake Hydrothermal System (BLHS), consisting of Borax Lake and the surrounding hot springs. BLHS is located near the center of the Alvord Basin in southeastern Oregon. The Alvord Basin is a north-south trending graben in the Northern Great Basin bounded by the Steens Mountains to the west and the Trout Creek Mountains to the east. We conducted a 2D seismic survey to characterize the geologic structure of the basin, a high-resolution 3D seismic survey to characterize the geologic structure of the BLHS, and a high-resolution 3D magnetic survey to characterize any lineaments in the bedrock that might control fluid flow in the BLHS. Previous results from the 2D seismic survey show a mid-basin basement high aligned approximately with the hot springs. In this study we present the results from the high-resolution 3D seismic and magnetic survey of the BLHS. We acquired the 3D seismic data using an SKS rifle and 240 channel recording system. The seismic survey covers approximately 90,000 sq. m with a maximum inline offset aperture of 225 m, crossline aperture of 75 m, and 360 degree azimuthal coverage. The coincidental magnetic survey was collected using a Geometrics 858G cesium vapor magnetometer. We designed both surveys to span nearly 100 active hydrothermal springs, including an approximately 50 m stepover in the trend of the surface expression of the hot springs. After preliminary processing, the 3D seismic data show continuous reflections up to 300 ms (~ 480 m). The initial interpretation of features seen in the 3D data cube include: normal faults dipping to the east and west, near-surface disturbances that are consistent with the trend of the hot springs, and significant near surface velocity anomalies

  11. 3D P-wave velocity structure of the deep Galicia rifted margin: A first analysis of the Galicia 3D wide-angle seismic dataset

    NASA Astrophysics Data System (ADS)

    Bayrakci, Gaye; Minshull, Timothy A.; Davy, Richard G.; Karplus, Marianne S.; Kaeschen, Dirk; Papenberg, Cord; Krabbenhoeft, Anne; Sawyer, Dale; Reston, Timothy J.; Shillington, Donna J.; Ranero, César R.

    2014-05-01

    Galicia 3D, a reflection-refraction and long offset seismic experiment was carried out from May through September 2013, at the Galicia rifted margin (in the northeast Atlantic Ocean, west of Spain) as a collaboration between US, UK, German and Spanish groups. The 3D multichannel seismic acquisition conducted by R/V Marcus Langseth covered a 64 km by 20 km (1280 km2) zone where the main geological features are the Peridotite Ridge (PR), composed of serpentinized peridotite and thought be upper mantle exhumed to the seafloor during rifting, and the S reflector which has been interpreted to be a low angle detachment fault overlain by fault bounded, rotated, continental crustal blocks. In the 3D box, two airgun arrays of 3300 cu.in. were fired alternately (in flip-flop configuration) every 37.5 m. All shots are recorded by 44 short period four component ocean bottom seismometers (OBS) and 26 ocean bottom hydrophones (OBH) deployed and recovered by R/V Poseidon, as well as four 6 km hydrophone streamers with 12.5 m channel spacing towed by R/V Marcus Langseth. We present the preliminary results of the first arrival time tomography study which is carried out with a subset of the wide-angle dataset, in order to generate a 3D P-wave velocity volume for the entire depth sampled by the reflection data. After the relocation of OBSs and OBHs, an automatic first-arrival time picking approach is applied to a subset of the dataset, which comprises more than 5.5 million source-receiver pairs. Then, the first-arrival times are checked visually, in 3-dimensions. The a priori model used for the first-arrival time tomography is built up using information from previous seismic surveys carried out at the Galicia margin (e.g. ISE, 1997). The FAST algorithm of Zelt and Barton (1998) is used for the first-arrival time inversion. The 3D P-wave velocity volume can be used in interpreting the reflection dataset, as a starting point for migration, to quantify the thinning of the crustal layers

  12. 3D-seismic observations of Late Pleistocene glacial dynamics on the central West Greenland margin

    NASA Astrophysics Data System (ADS)

    Hofmann, Julia; Knutz, Paul; Cofaigh, Colm Ó.

    2016-04-01

    Fast-flowing ice streams and outlet glaciers exert a major control on glacial discharge from contemporary and palaeo ice sheets. Improving our understanding of the extent and dynamic behaviour of these palaeo-ice streams is therefore crucial for predictions of the response of ice sheets to present and future climate warming and the associated implications for global sea level. This poster presents results from two 3D-seismic surveys located on the shelf adjoining the Disko Bay trough-mouth fan (TMF), one of the largest glacial outlet systems in Greenland. Located at the seaward terminus of the c. 370 km long cross-shelf Disko Trough, the Disko Bay TMF was generated by highly efficient subglacial sediment delivery onto the continental slopes during repeated ice-stream advances. A variety of submarine glacial landform assemblages are recognised on the seabed reflecting past ice-stream activity presumably related to glacial-interglacial cycles. The 3D-seismic volumes cover the shallow banks located north and south of the Disko Trough. The focus of this study is the seabed and the uppermost stratigraphic interval associated with the Late Stage of TMF development, presumably covering the late Pleistocene (Hofmann et al., submitted). Seabed morphologies include multiple sets of ridges up to 20 m high that extend in NW-SE direction for c. 30 km, and cross-cutting curvilinear furrows with maximum lengths of c. 9 km and average depths of c. 4.5 m. Back-stepping, arcuate scarps facing NW define the shelf break on the northern survey, comprising average widths of c. 4.5 km and incision depths of c. 27.5 m. The large transverse ridge features on the southern survey are likely ice-marginal and are interpreted as terminal moraine ridges recording the existence of a shelf-edge terminating, grounded Late Weichselian ice sheet. The furrows, most prominent on the outer shelf adjoining the shallow banks and partly incising the moraine ridges, are interpreted as iceberg ploughmarks

  13. Mount Etna: 3-D and 4-D structure using seismic tomography

    NASA Astrophysics Data System (ADS)

    Nunn, C.; Julian, B. R.; Foulger, G. R.; Patanè, D.; Ibáñez, J. M.; Briole, P.; Mhanna, N.

    2015-12-01

    We investigate the time-varying structure of Etna, an active stratovolcano in eastern Sicily, using seismic tomography. In volcanic systems, it is thought that the presence of fluids, cracks and pressurized gases can rapidly and drastically change the elastic properties of the host rocks. Recent work suggests that changes beneath Etna are detectable with seismic methods, and that these changes can be linked to volcanic activity. Temporal changes to Earth structure are commonly investigated by carrying out separate tomographic inversions for different epochs. However, repeated inversions of the same area are expected to vary, even if the structure itself does not change. This is due to variations in the seismic ray distribution and to observational errors. Potentially, changes between epochs which are due to experimental limitations can be misinterpreted as changes to the structure of the volcano. Consequently, we use a new tomographic program, TOMO4D, that inverts multiple data sets simultaneously [Julian & Foulger, Time-dependent seismic tomography, GJI, 2010]. This code imposes constraints which minimise the differences calculated between two epochs. The remaining structural variations are thus truly required to fit the data, and reflect changes which almost certainly exist between the two epochs. We have selected and relocated ~400 local earthquakes with at least 5 P and 5 S observations. They cover a period which includes several eruptions, from 1st November 2000 to 31st December 2006. We divide our data into different epochs and invert two epochs simultaneously. The models show a seismically fast central region, surrounded by a slower outer region. This suggests a central system of dykes or sills surrounded by volcanic sediments and country rock. At depths of 0-4 km below sea level the seismically fast region is not below the summit crater but is offset to the southwest. By monitoring the changes to the elastic parameters of the host rocks we observe temporal

  14. 3D multicomponent seismic characterization of a clastic reservoir in the Middle Magdalena Valley Basin, Colombia

    NASA Astrophysics Data System (ADS)

    Velasquez-Espejo, Antonio Jose

    The main goal of this research is to characterize the combined structural-stratigraphic trap of the Tenerife Field in the Middle Magdalena Valley Basin (MMVB), Colombia. For the first time in Colombia the structural and quantitative interpretation of modern three-dimensional multicomponent (3D-3C) seismic imaging enables a geometric description, a kinematic interpretation of the structural styles, and the facies distribution of the reservoir. A seismic petrophysics work-flow to better achieve the seismic well-tie. Edited and check-shot calibrated P-wave sonic logs were obtained and coefficients of the Gardner and Castagna equations were calibrated to match the density and shear-wave velocity depth trends for the basin. Seismic modeling was performed to evaluate the PP and PS seismic response of the reservoir interval (Mugrosa Formation). The structural interpretation methodology involves a 3D fault-correlation and horizon picking for both PP- and PS-PSTM data volumes. Geometric attributes such as coherence and curvature were used to enhance the structural discontinuities. The main unconformity of the Middle Eocene (MEU) was interpreted, and an attribute-assisted interpretation of the reservoir was conducted in detail. While P-wave data provided most of the structural interpretation, converted-wave data provide a better understanding of the faults. Traditionally, compressive thrust-propagation folds and tectonic inversion have been considered as the main mechanisms controlling the deformation in the MMVB. However, the new interpretation shown in this work provides a different structural concept that involves two major structural styles: 1. Under the MEU the Late Cretaceous and Early Paleocene deformation, dominated by east-verging thrust and partially inverted Mesozoic normal faults, is preserved. Associated folds exhibit a north-south strike, and their structural development is controlled by a long-lived structural element that dominates the area (the Infantas

  15. Evolution of Submarine Gullies on a Prograding Slope: Insights from 3D Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Shumaker, L.; Jobe, Z. R.

    2014-12-01

    Submarine gullies are common features on continental slopes on both passive and active margins, but the processes dictating gully formation and the role of gullies in deep-water sediment transport are topics of debate. The geometries of gullies can provide clues to understanding the processes by which they initiate and grow, particularly when considered in the context of surrounding submarine geomorphology. Further confidence in these interpretations can be gained by tracking the temporal history of gullies with evolution of the continental margin. The 500 km2 Tui 3D seismic survey from the Taranaki Basin, New Zealand, shows continental slope gullies and other channel features in a ~1 km-thick package of prograding shelf-slope clinoforms that developed over Pliocene-Pleistocene time. This dataset allows for documentation of gullies over ~3 Ma, through numerous cycles of initiation and burial. For this study, we manually interpreted clinoform packages to generate 'paleo-seafloor' surfaces that provide context such as position of the shelf edge, slope gradient and azimuth, and relative progradation and aggradation magnitudes. Gully geometries were obtained from detailed seismic interpretation guided by semblance and RMS amplitude imaging on these surfaces. Gullies are low sinuosity, with widths ranging from ~50-150 m and depths from a few tens to <100 m. Gullies are observed to grow in width and relief downslope without evidence for aggradational confinement (levees), and in some cases form gully 'complexes' hundreds of m wide in the lower slope region. These complexes are present through >150 m of stratigraphy, indicating that they are long-lived features on the slope. This further indicates that the frequency of flows along the gullies was enough to maintain their topographic expression during slope progradation and aggradation, and suggests that gullies play an integral role in transport processes on the slope.

  16. Comparative velocity structure of active Hawaiian volcanoes from 3-D onshore-offshore seismic tomography

    USGS Publications Warehouse

    Park, J.; Morgan, J.K.; Zelt, C.A.; Okubo, P.G.; Peters, L.; Benesh, N.

    2007-01-01

    We present a 3-D P-wave velocity model of the combined subaerial and submarine portions of the southeastern part of the Island of Hawaii, based on first-arrival seismic tomography of marine airgun shots recorded by the onland seismic network. Our model shows that high-velocity materials (6.5-7.0??km/s) lie beneath Kilauea's summit, Koae fault zone, and the upper Southwest Rift Zone (SWRZ) and upper and middle East Rift Zone (ERZ), indicative of magma cumulates within the volcanic edifice. A separate high-velocity body of 6.5-6.9??km/s within Kilauea's lower ERZ and upper Puna Ridge suggests a distinct body of magma cumulates, possibly connected to the summit magma cumulates at depth. The two cumulate bodies within Kilauea's ERZ may have undergone separate ductile flow seaward, influencing the submarine morphology of Kilauea's south flank. Low velocities (5.0-6.3??km/s) seaward of Kilauea's Hilina fault zone, and along Mauna Loa's seaward facing Kao'iki fault zone, are attributed to thick piles of volcaniclastic sediments deposited on the submarine flanks. Loihi seamount shows high-velocity anomalies beneath the summit and along the rift zones, similar to the interpreted magma cumulates below Mauna Loa and Kilauea volcanoes, and a low-velocity anomaly beneath the oceanic crust, probably indicative of melt within the upper mantle. Around Kilauea's submarine flank, a high-velocity anomaly beneath the outer bench suggests the presence of an ancient seamount that may obstruct outward spreading of the flank. Mauna Loa's southeast flank is also marked by a large, anomalously high-velocity feature (7.0-7.4??km/s), interpreted to define an inactive, buried volcanic rift zone, which might provide a new explanation for the westward migration of Mauna Loa's current SWRZ and the growth of Kilauea's SWRZ. ?? 2007 Elsevier B.V. All rights reserved.

  17. 3-D Seismic Images of Mud Volcano North Alex, West-Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Bialas, J.; Klaeschen, D.; Papenberg, C. A.; Gehrmann, R.; Sommer, M.

    2009-12-01

    Mud volcanoes within shelf areas are the bathymetric expression of mobilized overpressured sediments causing a feature of possible instability within the slope. Such a scene is given in the West-Nile Delta offshore Alexandria, Egypt at 700 m water depth. The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. Deep-cutting channel systems like the Rosetta channel characterize the continental slope. Bathymetric expressions of slides and numerous mud volcanoes in the area are expressions of active processes, which contribute to the ongoing modification of the slope. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A grid of 2-D seismic profiles did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. They can be tracked up to the seafloor indicating ongoing tectonic activity of the slope area. A recently build 3-D acquisition system suitable for mid-size research vessels was applied to collect an active seismic cube of the mud volcano. Based on the P-Cable design 11 parallel streamers (each 12.5 m long with 1.5 m group interval) were used to record shots of a single 210 cinch GI airgun. After stacking a 3D time migration within the cube provided final signal to noise reduction and filled

  18. A 3D S-wave model of the Valhall subsurface from ambient seismic noise tomography

    NASA Astrophysics Data System (ADS)

    Mordret, A.; Landes, M.; Shapiro, N.; Singh, S. C.; Roux, P.

    2013-12-01

    We present a depth inversion of Scholte wave group and phase velocity maps obtained from cross-correlation of 6.5 hours of noise data from the Valhall Life of Field Seismic (LoFS) network. We computed 2 690 040 vertical-vertical component cross-correlations from the 2320 available sensors, turning each sensor into a virtual source emitting Scholte waves. We used a traditional straight-ray surface-wave tomography to compute the group velocity map. The phase velocity maps have been computed using the Eikonal tomography method. For every virtual source, we measured the Scholte wave phase travel times to all other stations and interpolated them on a regular grid. This phase travel-time surface is inverted into phase velocity map via applying the eikonal equation. The contributions from all 2320 virtual sources are stacked to create the final phase velocity map of the Valhall subsurface. Scholte wave isotropic phase velocity maps at periods between 0.65 s and 1.6 s show a coherent geomorphological pattern dominated by paleo-channels in the shallower part. We also retrieved the azimuthal anisotropy and its lateral variations showing a characteristic elliptical pattern around the central exploitation platform. The inversion of these maps in depth using the Neighbourhood Algorithm allowed us to create a high resolution 3D S-wave model of the first 600 m of the Valhall subsurface and to precise the locations of geological structures at depth. These results would have important implication for shear wave statics and monitoring of sea-floor subsidence due to oil extraction. The 3D model could also be a good candidate for a starting model used in full-waveform inversions.

  19. High-resolution 3-D S-wave Tomography of upper crust structures in Yilan Plain from Ambient Seismic Noise

    NASA Astrophysics Data System (ADS)

    Chen, Kai-Xun; Chen, Po-Fei; Liang, Wen-Tzong; Chen, Li-Wei; Gung, YuanCheng

    2015-04-01

    The Yilan Plain (YP) in NE Taiwan locates on the western YP of the Okinawa Trough and displays high geothermal gradients with abundant hot springs, likely resulting from magmatism associated with the back-arc spreading as attested by the offshore volcanic island (Kueishantao). YP features NS distinctive characteristics that the South YP exhibits thin top sedimentary layer, high on-land seismicity and significant SE movements, relative those of the northern counterpart. A dense network (~2.5 km station interval) of 89 Texan instruments was deployed in Aug. 2014, covering most of the YP and its vicinity. The ray path coverage density of each 0.015 degree cells are greater than 150 km that could provide the robustness assessment of tomographic results. We analyze ambient noise signals to invert a high-resolution 3D S-wave model for shallow velocity structures in and around YP. The aim is to investigate the velocity anomalies corresponding to geothermal resources and the NS geological distinctions aforementioned. We apply the Welch's method to generate empirical Rayleigh wave Green's functions between two stations records of continuous vertical components. The group velocities of thus derived functions are then obtained by the multiple-filter analysis technique measured at the frequency range between 0.25 and 1 Hz. Finally, we implement a wavelet-based multi-scale parameterization technique to construct 3D model of S-wave velocity. Our first month results exhibit low velocity in the plain, corresponding existing sediments, those of whole YP show low velocity offshore YP and those of high-resolution south YP reveal stark velocity contrast across the Sanshin fault. Key words: ambient seismic noises, Welch's method, S-wave, Yilan Plain

  20. 3D Seismic Reflection Data: Has the Geological Hubble Retained Its Focus?

    NASA Astrophysics Data System (ADS)

    Jackson, Christopher

    2016-04-01

    In their seminal paper in 2002, Joe Cartwright and Mads Huuse referred to 3D seismic reflection data as the 'Geological Hubble', illustrating how these data had the potential to revolutionise our understanding of the genesis and evolution of sedimentary basins. 14 years on, I will here outline just some of the key recent advances made in our understanding of basin structure and stratigraphy, focusing on: (i) the intrusion and extrusion of igneous rocks; (ii) salt tectonics, with particular emphasis on intrasalt structure and the kinematics and mechanics of diapirism; (iii) the geometry and growth of normal faults; and (iv) the structure and emplacement of mass-transport complexes (MTCs). I will stress that future advances at least partly relies on hydrocarbon exploration companies and government agencies continuing to make their data freely available via easy-to-access data portals. I will issue a clarion call to academics, stressing that 'geodynamicists', sedimentologists, structural geologists and geomorphologists, amongst others, can benefit from utilising what I believe are currently an underused data type.

  1. 3-D seismic evidence of the effects of carbonate karst collapse on overlying clastic stratigraphy and reservoir compartmentalization

    SciTech Connect

    Hardage, B.A.; Carr, D.L.; Simmons, J.L. Jr.; Jons, R.A.; Lancaster, D.E.; Elphick, R.Y.; Pendleton, V.M.

    1996-09-01

    A multidisciplinary team, composed of stratigraphers, petrophysicists, reservoir engineers, and geophysicists, studied a portion of Boonsville gas field in the Fort Worth Basin of north-central Texas to determine how modern techniques can be combined to understand the mechanisms by which fluvio-deltaic depositional processes create reservoir compartmentalization in a low- to moderate-accommodation basin. An extensive database involving well logs, cores, production, and pressure data from more than 200 wells, 26 mi{sup 2} of 3-D seismic data, vertical seismic profiles, and checkshots was assembled to support this investigation. The authors found the most important geologic influence on stratigraphy and reservoir compartmentalization in this basin to be the existence of numerous karst collapse chimneys over the area covered. These near-vertical karst collapses originated in, or near, the deep Ordovician-age Ellenburger carbonate section and created vertical chimneys extending as high as 2,500 ft above their point of origin, causing significant disruptions in the overlying clastic strata.

  2. Effect of 3-D viscoelastic structure on post-seismic relaxation from the 2004 M = 9.2 Sumatra earthquake

    USGS Publications Warehouse

    Pollitz, F.; Banerjee, P.; Grijalva, K.; Nagarajan, B.; Burgmann, R.

    2008-01-01

    The 2004 M=9.2 Sumatra-Andaman earthquake profoundly altered the state of stress in a large volume surrounding the ???1400 km long rupture. Induced mantle flow fields and coupled surface deformation are sensitive to the 3-D rheology structure. To predict the post-seismic motions from this earthquake, relaxation of a 3-D spherical viscoelastic earth model is simulated using the theory of coupled normal modes. The quasi-static deformation basis set and solution on the 3-D model is constructed using: a spherically stratified viscoelastic earth model with a linear stress-strain relation; an aspherical perturbation in viscoelastic structure; a 'static'mode basis set consisting of Earth's spheroidal and toroidal free oscillations; a "viscoelastic" mode basis set; and interaction kernels that describe the coupling among viscoelastic and static modes. Application to the 2004 Sumatra-Andaman earthquake illustrates the profound modification of the post-seismic flow field at depth by a slab structure and similarly large effects on the near-field post-seismic deformation field at Earth's surface. Comparison with post-seismic GPS observations illustrates the extent to which viscoelastic relaxation contributes to the regional post-seismic deformation. ?? Journal compilation ?? 2008 RAS.

  3. 3-D Seismic Images of Mud Volcano North Alex, West-Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Bialas, Joerg; Klaeschen, Dirk; Papenberg, Cord; Gehrmann, Romina; Sommer, Malte

    2010-05-01

    Mud volcanoes within shelf areas are the bathymetric expression of mobilized overpressured sediments causing a feature of possible instability within the slope. Such a scene is given in the West-Nile Delta offshore Alexandria, Egypt at 700 m water depth, ,which was studied during a RWE Dea funded research project. The West Nile Delta forms part of the source of the large turbiditic Nile Deep Sea Fan. Since the late Miocene sediments have formed an up to 10 km thick pile, which includes about 1 - 3 km of Messinian evaporates. The sediment load of the overburden implies strong overpressures and salt-related tectonic deformation. Both are favourable for fluid migration towards the seafloor guided by the fractured margin. Deep-cutting channel systems like the Rosetta channel characterize the continental slope. Bathymetric expressions of slides and numerous mud volcanoes in the area are expressions of active processes, which contribute to the ongoing modification of the slope. The western deltaic system, Rosetta branch, has formed an 80 km wide continental shelf. Here at 700 m water depth the mud volcano North Alex developed his circular bathymetric feature, which proved to be an active gas and mud-expelling structure. A grid of 2-D seismic profiles did reveal a large set of faults located within the main mud volcano as well as surrounding the structure. Internal faults are mainly related to episodic mud expulsion processes and continuous gas and fluid production. Deep cutting external faults surround the structure in a half circle shape. They can be tracked up to the seafloor indicating ongoing tectonic activity of the slope area. A recently build 3-D acquisition system (funded by RWE Dea) suitable for mid-size research vessels was applied to collect an active seismic cube of the mud volcano. Based on the P-Cable design 11 parallel streamers (each 12.5 m long with 1.5 m group interval) were used to record shots of a single 210 cinch GI airgun. Based on GPS positions of

  4. 3-D Vs ambient noise tomography around the Meishan fault zone in southwestern Taiwan from dense seismic array

    NASA Astrophysics Data System (ADS)

    Cheng, C. Y.; Kuochen, H.; Yao, H.; Chen, K. X.; Ma, K. F.

    2016-12-01

    1906 7.1 Meishan earthquake occurred near Chiayi city in southwestern Taiwan and resulted in more than three thousands casualties and six thousands of buildings collapsed. Based on the geological survey, the Meishan fault zone a right-lateral strike-slip fault with a length of 25 kilometers, was the main contributor for this event. In previous studies, many researchers have done lot of investigation about the Meishan Fault zone, including geologic researches at surface and seismic explorations at shallow crust. However, there is still limited information about 3-D shallow crustal structure of this study area. Therefore, we deployed 100 Texan instruments ( 2 km interval) between Aug. and Nov. 2015, covered around the Meishan Fault zone. We obtained a 3-D shear wave shallow crustal velocity structure using ambient noise tomography. The reliable periods of phase velocity from Rayleigh wave are 0.6 to 6.8 seconds, which correspond to around 0-6 km at depths. As a result, the sub-surface structure around the Meishan fault zone is very complex. The structures of the basement varied across the Meishan fault zone: the basement is thicker in the north of the fault zone than that in the south. Also, Xiaomei anicline near the fault zone is observed from this study.

  5. Detailed Gas Chimney Structures in Joetsu Area at Southeastern Margin of Japan Sea, Revealed by High-Resolution 3D Seismic Survey (HR3D)

    NASA Astrophysics Data System (ADS)

    Ohkawa, S.; Hiruta, A.; Yanagimoto, Y.; Matsumoto, R.; Asakawa, E.

    2016-12-01

    To delineate the detailed structure of the gas chimneys, a high-resolution three-dimensional seismic survey (HR3D) was carried out in Joetsu area, at the southeastern margin of Japan Sea where hydrate-related mound and pockmark systems with gas chimneys are widely developed. HR3D data have successfully revealed the fine structure of gas chimneys which were not clearly imaged by the existing seismic data, such as sub-bottom profilers and conventional large-scale 3D surveys for petroleum exploration. HR3D data are also useful to interpolate and extrapolate spatially the geological/geophysical information obtained at wells most of which were drilled into the gas hydrate concentrated zones (GHCZs.) In the areas of low hydrate concentration, the reflections show a parallel-stratified pattern and the bottom simulating reflector (BSR) is parallel to the sea floor reflections. On the other hand, GHCZs are seismologically characterized by (1) strong sea floor reflections on the chimney mounds, (2) chaotic reflection patterns in the chimneys, and (3) pull-up of bottom simulating reflector (BSR) as shown in the attached figure. Strong sea floor reflections suggest that solid hydrates deposit in the very shallow part beneath the sea floor and the chaotic reflections indicate the hydrates are not continuously layered but interspersedly distributed. The BSR pull-up phenomena as much as 70 80msec are caused by high-velocity materials existing between the sea floor and the BSR. The sonic logs acquired by LWD at wells drilled into GHCZs show high velocity up to 3,800 m/s in the massive hydrates. The pull-up times estimated from the sonic data are consistent in general with the observed pull-up times on HR3D sections, suggesting the pull-up times could be useful for a preliminary evaluation of hydrate zones before drilling and/or in the areas without well data. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI

  6. CO2 mass estimation visible in time-lapse 3D seismic data from a saline aquifer and uncertainties

    NASA Astrophysics Data System (ADS)

    Ivanova, A.; Lueth, S.; Bergmann, P.; Ivandic, M.

    2014-12-01

    At Ketzin (Germany) the first European onshore pilot scale project for geological storage of CO2 was initiated in 2004. This project is multidisciplinary and includes 3D time-lapse seismic monitoring. A 3D pre-injection seismic survey was acquired in 2005. Then CO2 injection into a sandstone saline aquifer started at a depth of 650 m in 2008. A 1st 3D seismic repeat survey was acquired in 2009 after 22 kilotons had been injected. The imaged CO2 signature was concentrated around the injection well (200-300 m). A 2nd 3D seismic repeat survey was acquired in 2012 after 61 kilotons had been injected. The imaged CO2 signature further extended (100-200 m). The injection was terminated in 2013. Totally 67 kilotons of CO2 were injected. Time-lapse seismic processing, petrophysical data and geophysical logging on CO2 saturation have allowed for an estimate of the amount of CO2 visible in the seismic data. This estimate is dependent upon a choice of a number of parameters and contains a number of uncertainties. The main uncertainties are following. The constant reservoir porosity and CO2 density used for the estimation are probably an over-simplification since the reservoir is quite heterogeneous. May be velocity dispersion is present in the Ketzin reservoir rocks, but we do not consider it to be large enough that it could affect the mass of CO2 in our estimation. There are only a small number of direct petrophysical observations, providing a weak statistical basis for the determination of seismic velocities based on CO2 saturation and we have assumed that the petrophysical experiments were carried out on samples that are representative for the average properties of the whole reservoir. Finally, the most of the time delay values in the both 3D seismic repeat surveys within the amplitude anomaly are near the noise level of 1-2 ms, however a change of 1 ms in the time delay affects significantly the mass estimate, thus the choice of the time-delay cutoff is crucial. In spite

  7. A probabilistic approach to jointly integrate 3D/4D seismic, production data and geological information for building reservoir models

    NASA Astrophysics Data System (ADS)

    Castro, Scarlet A.

    Reservoir modeling aims at understanding static and dynamic components of the reservoir in order to make decisions about future surface operations. The practice of reservoir modeling calls for the integration of expertise from different disciplines, as well as the in tegration of a wide variety of data: geological data, (core data, well-logs, etc.), production data (fluid rates or volumes, pressure data, etc.), and geophysical data (3D seismic data). Although a single 3D seismic survey is the most common geophysical data available for most reservoirs, a suite of several 3D seismic surveys (4D seismic data) acquired for monitoring production can be available for mature reservoirs. The main contribution of this dissertation is to incorporate 4D seismic data within the reservoir modeling workflow while honoring all other available data. This dissertation proposes two general approaches to include 4D seismic data into the reservoir modeling workflow. The Probabilistic Data Integration approach (PDI), which consists of modeling the information content of 4D seismic through a spatial probability of facies occurrence; and the Forward Modeling (FM) approach, which consists of matching 4D seismic along with production data. The FM approach requires forward modeling the 4D seismic response, which requires to downscale the flow simulation response. This dissertation introduces a novel dynamic downscaling method that takes into account both static information (high-resolution per meability field) and dynamic information in the form of coarsened fluxes and saturations (flow simulation on the coarsened grid). The two proposed approaches (PDI and FM approaches) are applied to a prominent field in the North Sea, to model the channel facies of a fluvial reservoir. The PDI approach constrained the reservoir model to the spatial probability of facies occurrence (obtained from a calibration between well-log and 4D seismic data) as well as other static data while satisfactorily history

  8. Investigation Into the Accuracy of 3D Surface Roughness Characteristics

    NASA Astrophysics Data System (ADS)

    Kumermanis, M.; Rudzitis, J.; Mozga, N.; Ancans, A.; Grislis, A.

    2014-04-01

    The existing standards for surface roughness cover only two dimensions, while in reality this is three-dimensional (3D). In particular, the 3D surface roughness parameters are important for solving the contact surface mechanics problems as related to the accuracy of 3D surface roughness characteristics. One of the most important factors for determination of 3D characteristics is the number of data points (NDP) on the x- and y-axes (i.e. in cut-off length). The NDP has a profound effect on the accuracy of measurement results, measuring time and volume of the output data (especially along the y-axis, where the NDP is identical to the number of parallel profiles). At a too small NDP the results will be incorrect and with too broad scatter, while a too large NDP - though not enlarging the range of basic information - considerably increases the measuring time. Therefore, the aim of the work was to find the optimal NDP for such surface processing methods as grinding, spark erosion and shot methods of surface treatment. Eksistējošie virsmas raupjuma standarti apskata virsmas raupjumu tikai divās dimensijās. Tomēr reālais virsmas raupjums pēc savas dabas ir trīsdimensiju (3D) objekts. Līdz ar to virsmas raupjums ir jāraksturo ar 3D parametriem. Un no šo parametru noteikšanas precizitātes ir atkarīgi tālākie virsmas aprēķini, piemēram, virsmu kontaktēšanās process. Viens no svarīgākajiem faktoriem, raksturojot virsmas raupjumu 3D, pielietojot kontakta tipa mēriekārtas, ir datu punktu skaits pa abām mērīšanas asīm x un y. Ar datu punktu skaitu mēs saprotam to skaitu mērīšanas bāzes garumā. Datu punktu skaits būtiski ietekmē sagaidāmo mērījumu rezultātu precizitāti, mērīšanai nepieciešamo laiku un izejas datu faila izmērus (sevišķi y-ass virzienā, kur katrs datu punkts ir paralēls profils). Datu punktu skaitam ir jābūt optimālam. Pārāk mazs punktu skaits noved pie neprecīziem rezultātiem un lielas to izkliedes, savuk

  9. Performance Investigation of a Handheld 3d Scanner to Define Good Practices for Small Artefact 3d Modeling

    NASA Astrophysics Data System (ADS)

    Lachat, E.; Landes, T.; Grussenmeyer, P.

    2017-08-01

    Handheld 3D scanners can be used to complete large scale models with the acquisition of occluded areas or small artefacts. This may be of interest for digitization projects in the field of Cultural Heritage, where detailed areas may require a specific treatment. Such sensors present the advantage of being easily portable in the field, and easily usable even without particular knowledge. In this paper, the Freestyle3D handheld scanner launched on the market in 2015 by FARO is investigated. Different experiments are described, covering various topics such as the influence of range or color on the measurements, but also the precision achieved for geometrical primitive digitization. These laboratory experiments are completed by acquisitions performed on engraved and sculpted stone blocks. This practical case study is useful to investigate which acquisition protocol seems to be the more adapted and leads to precise results. The produced point clouds will be compared to photogrammetric surveys for the purpose of their accuracy assessment.

  10. Using 3D Glyph Visualization to Explore Real-time Seismic Data on Immersive and High-resolution Display Systems

    NASA Astrophysics Data System (ADS)

    Nayak, A. M.; Lindquist, K.; Kilb, D.; Newman, R.; Vernon, F.; Leigh, J.; Johnson, A.; Renambot, L.

    2003-12-01

    The study of time-dependent, three-dimensional natural phenomena like earthquakes can be enhanced with innovative and pertinent 3D computer graphics. Here we display seismic data as 3D glyphs (graphics primitives or symbols with various geometric and color attributes), allowing us to visualize the measured, time-dependent, 3D wave field from an earthquake recorded by a certain seismic network. In addition to providing a powerful state-of-health diagnostic of the seismic network, the graphical result presents an intuitive understanding of the real-time wave field that is hard to achieve with traditional 2D visualization methods. We have named these 3D icons `seismoglyphs' to suggest visual objects built from three components of ground motion data (north-south, east-west, vertical) recorded by a seismic sensor. A seismoglyph changes color with time, spanning the spectrum, to indicate when the seismic amplitude is largest. The spatial extent of the glyph indicates the polarization of the wave field as it arrives at the recording station. We compose seismoglyphs using the real time ANZA broadband data (http://www.eqinfo.ucsd.edu) to understand the 3D behavior of a seismic wave field in Southern California. Fifteen seismoglyphs are drawn simultaneously with a 3D topography map of Southern California, as real time data is piped into the graphics software using the Antelope system. At each station location, the seismoglyph evolves with time and this graphical display allows a scientist to observe patterns and anomalies in the data. The display also provides visual clues to indicate wave arrivals and ~real-time earthquake detection. Future work will involve adding phase detections, network triggers and near real-time 2D surface shaking estimates. The visuals can be displayed in an immersive environment using the passive stereoscopic Geowall (http://www.geowall.org). The stereographic projection allows for a better understanding of attenuation due to distance and earth

  11. Towards Computing Full 3D Seismic Sensitivity: The Axisymmetric Spectral Element Method

    NASA Astrophysics Data System (ADS)

    Nissen-Meyer, T.; Fournier, A.; Dahlen, F. A.

    2004-12-01

    Finite frequency tomography has recently provided detailed images of the Earth's deep interior. However, the Fréchet sensitivity kernels used in these inversions are calculated using ray theory and can therefore not account for D''-diffracted phases or any caustics in the wavefield, as e.g. occurring in phases used to map boundary layer topography. Our objective is to compile an extensive set of full sensitivity kernels based on seismic forward modeling to allow for inversion of any seismic phase. The sensitivity of the wavefield due to a scatterer off the theoretical ray path is generally determined by the convolution of the source-to-scatterer response with, using reciprocity, the receiver-to-scatterer response. Thus, exact kernels require the knowledge of the Green's function for the full moment tensor (i.e., source) and body forces (i.e., receiver components) throughout the model space and time. We develop an axisymmetric spectral element method for elastodynamics to serve this purpose. The axisymmetric approach takes advantage of the fact that kernels are computed upon a spherically symmetric Earth model. In this reduced dimension formulation, all moment tensor elements and single forces can be included and collectively unfold in six different 2D problems to be solved separately. The efficient simulations on a 2D mesh then allow for currently unattainable high resolution at low hardware requirements. The displacement field {u} for the 3D sphere can be expressed as {u}( {x}, {t})= {u}( {x}φ =0}, {t}) {f(φ ), where φ =0 represents the 2D computational domain and {f}(φ ) are trigonometric functions. Here, we describe the variational formalism for the full multipole source system and validate its implementation against normal mode solutions for the solid sphere. The global mesh includes several conforming coarsening levels to minimize grid spacing variations. In an effort of algorithmic optimization, the discretization is acquired on the basis of matrix

  12. Evaluation of Jumping and Creeping Regularization Approaches Applied to 3D Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Liu, M.; Ramachandran, K.

    2011-12-01

    are evaluated on a synthetic 3-D true model obtained from a large scale experiment. The evaluation is performed for jumping and creeping approaches for various levels of smoothing constraints, and initial models. The final models are compared against the true models to compute residual distance between the models. Horizontal and vertical roughness in the final models are computed and compared with the true model roughness. Correlation between the true and final models is computed to evaluate the similarities of spatial patterns in the models. The study is also used to show that average 1-D models derived from the final models are very close, indicating that this will be an optimal approach to construct 1-D starting models.

  13. 3D crustal structure beneath the Costa Rica Rift from seismic tomography: insight into magmatic activity

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Tong, V.; Wilson, D. J.; Hobbs, R. W.; Haughton, G.; Murton, B. J.

    2016-12-01

    During the cruise JC114, which was carried out in the intermediate-spreading Costa Rica Rift(CRR) in 2015, we acquired seismic records from 25 ocean-bottom seismographs in a 5x5 grid with an approximate node spacing of 5 km over the rift's axis. We picked 69,000 Pg and Pn events and inverted 3D crustal Vp structure beneath the CRR by using the First-Arrival Refraction Tomography (FAST). Our results show that at the depth of 1.0 2.0km below sea floor beneath the axis, there exists a 5km-wide low-velocity zone(LVZ), which extends along the axis but breaks into two segments at 83°48'W. At a deeper depth (>2.5km below sea floor), an underlying wider LVZ extends horizontally and vertically, probably stretching through the Moho. The shallower LVZ indicates the accretion of magma in the upper crust or the presence of highly porous or cracked rocks, while the deeper LVZ is inferred to be a partially molten zone, i.e. the representative of the axial magma chamber. The deeper LVZ is connected with the shallower one by upwelling conduits, which bifurcate and provide melts for both the west and east segments of the overlying LVZ. The conduit to the east segment is more prominent, providing more robust magma supply and leading to more intense negative velocity perturbation. It may reflect that the magma supply is fluctuating and migrating in the lower crust and the upper mantle. From analysing traveltime residual to study azimuthal anisotropy, we conclude that the fast direction varies roughly around 90° in the upper crust, implying that the vertically aligned cracks are nearly parallel to the axis and favour along-axis hydrothermal circulation. By comparing the anisotropy features of the two flanks of the CRR, we propose that the magmatic activity is more vigorous in the shallow subsurface of the north flank, i.e. the Cocos Plate. This research is part of a major, interdisciplinary NERC-funded collaboration entitled: Oceanographic and Seismic Characterisation of heat

  14. Understanding the seismic wave propagation inside and around an underground cavity from a 3D numerical survey

    NASA Astrophysics Data System (ADS)

    Esterhazy, Sofi; Schneider, Felix; Perugia, Ilaria; Bokelmann, Götz

    2017-04-01

    Motivated by the need to detect an underground cavity within the procedure of an On-Site-Inspection (OSI) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), which might be caused by a nuclear explosion/weapon testing, we aim to provide a basic numerical study of the wave propagation around and inside such an underground cavity. One method to investigate the geophysical properties of an underground cavity allowed by the Comprehensive Nuclear-test Ban Treaty is referred to as "resonance seismometry" - a resonance method that uses passive or active seismic techniques, relying on seismic cavity vibrations. This method is in fact not yet entirely determined by the Treaty and so far, there are only very few experimental examples that have been suitably documented to build a proper scientific groundwork. This motivates to investigate this problem on a purely numerical level and to simulate these events based on recent advances in numerical modeling of wave propagation problems. Our numerical study includes the full elastic wave field in three dimensions. We consider the effects from an incoming plane wave as well as point source located in the surrounding of the cavity at the surface. While the former can be considered as passive source like a tele-seismic earthquake, the latter represents a man-made explosion or a viborseis as used for/in active seismic techniques. Further we want to demonstrate the specific characteristics of the scattered wave field from a P-waves and S-wave separately. For our simulations in 3D we use the discontinuous Galerkin Spectral Element Code SPEED developed by MOX (The Laboratory for Modeling and Scientific Computing, Department of Mathematics) and DICA (Department of Civil and Environmental Engineering) at the Politecnico di Milano. The computations are carried out on the Vienna Scientific Cluster (VSC). The accurate numerical modeling can facilitate the development of proper analysis techniques to detect the remnants of an

  15. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N. P. Paulsson

    2006-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to perform high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology has been hampered by the lack of acquisition technology necessary to record large volumes of high frequency, high signal-to-noise-ratio borehole seismic data. This project took aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array has removed the technical acquisition barrier for recording the data volumes necessary to do high resolution 3D VSP and 3D cross-well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that promise to take the gas industry to the next level in their quest for higher resolution images of deep and complex oil and gas reservoirs. Today only a fraction of the oil or gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of detailed compartmentalization of oil and gas reservoirs. In this project, we developed a 400 level 3C borehole seismic receiver array that allows for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. This new array has significantly increased the efficiency of recording large data volumes at sufficiently dense spatial sampling to resolve reservoir complexities. The receiver pods have been fabricated and tested to withstand high temperature (200 C/400 F) and high pressure (25,000 psi), so that they can operate in wells up to 7,620 meters (25,000 feet) deep. The receiver array is deployed on standard production or drill tubing. In combination with 3C surface seismic or 3C borehole seismic sources, the 400

  16. 3-D seismic tomography of the lithosphere and its geodynamic implications beneath the northeast India region

    NASA Astrophysics Data System (ADS)

    Raoof, J.; Mukhopadhyay, S.; Koulakov, I.; Kayal, J. R.

    2017-05-01

    We have evolved 3-D seismic velocity structures in northeast India region and its adjoining areas to understand the geodynamic processes of Indian lithosphere that gently underthrusts under the Himalayas and steeply subducts below the Indo-Burma Ranges. The region is tectonically buttressed between the Himalayan arc to the north and the Indo-Burmese arc to the east. The tomographic image shows heterogeneous structure of lithosphere depicting different tectonic blocks. Though our results are limited to shallower depth (0-90 km), it matches well with the deeper continuation of lithospheric structure obtained in an earlier study. We observe low-velocity structure all along the Eastern Himalayas down to 70 km depth, which may be attributed to deeper roots/thicker crust developed by underthrusting of Indian plate. Parallel to this low-velocity zone lies a high-velocity zone in foredeep region, represents the Indian lithosphere. The underthrusting Indian lithosphere under the Himalayas as well as below the Indo-Burma Ranges is well reflected as a high-velocity dipping structure. The buckled up part of bending Indian plate in study region, the Shillong Plateau-Mikir Hills tectonic block, is marked as a high-velocity structure at shallower depth. The Eastern Himalayan Syntaxis, tectonic block where the two arcs meet, is identified as a high-velocity structure. The Bengal Basin, tectonic block to the south of Shillong Plateau, shows low velocity due to its thicker sediments. Based on the tomographic image, a schematic model is presented to elucidate the structure and geodynamics of Indian lithosphere in study region.

  17. Well log analysis to assist the interpretation of 3-D seismic data at Milne Point, north slope of Alaska

    USGS Publications Warehouse

    Lee, Myung W.

    2005-01-01

    In order to assess the resource potential of gas hydrate deposits in the North Slope of Alaska, 3-D seismic and well data at Milne Point were obtained from BP Exploration (Alaska), Inc. The well-log analysis has three primary purposes: (1) Estimate gas hydrate or gas saturations from the well logs; (2) predict P-wave velocity where there is no measured P-wave velocity in order to generate synthetic seismograms; and (3) edit P-wave velocities where degraded borehole conditions, such as washouts, affected the P-wave measurement significantly. Edited/predicted P-wave velocities were needed to map the gas-hydrate-bearing horizons in the complexly faulted upper part of 3-D seismic volume. The estimated gas-hydrate/gas saturations from the well logs were used to relate to seismic attributes in order to map regional distribution of gas hydrate inside the 3-D seismic grid. The P-wave velocities were predicted using the modified Biot-Gassmann theory, herein referred to as BGTL, with gas-hydrate saturations estimated from the resistivity logs, porosity, and clay volume content. The effect of gas on velocities was modeled using the classical Biot-Gassman theory (BGT) with parameters estimated from BGTL.

  18. SHEAR WAVE SEISMIC STUDY COMPARING 9C3D SV AND SH IMAGES WITH 3C3D C-WAVE IMAGES

    SciTech Connect

    John Beecherl; Bob A. Hardage

    2004-07-01

    The objective of this study was to compare the relative merits of shear-wave (S-wave) seismic data acquired with nine-component (9-C) technology and with three-component (3-C) technology. The original proposal was written as if the investigation would be restricted to a single 9-C seismic survey in southwest Kansas (the Ashland survey), on the basis of the assumption that both 9-C and 3-C S-wave images could be created from that one data set. The Ashland survey was designed as a 9-C seismic program. We found that although the acquisition geometry was adequate for 9-C data analysis, the source-receiver geometry did not allow 3-C data to be extracted on an equitable and competitive basis with 9-C data. To do a fair assessment of the relative value of 9-C and 3-C seismic S-wave data, we expanded the study beyond the Ashland survey and included multicomponent seismic data from surveys done in a variety of basins. These additional data were made available through the Bureau of Economic Geology, our research subcontractor. Bureau scientists have added theoretical analyses to this report that provide valuable insights into several key distinctions between 9-C and 3-C seismic data. These theoretical considerations about distinctions between 3-C and 9-C S-wave data are presented first, followed by a discussion of differences between processing 9-C common-midpoint data and 3-C common-conversion-point data. Examples of 9-C and 3-C data are illustrated and discussed in the last part of the report. The key findings of this study are that each S-wave mode (SH-SH, SV-SV, or PSV) involves a different subsurface illumination pattern and a different reflectivity behavior and that each mode senses a different Earth fabric along its propagation path because of the unique orientation of its particle-displacement vector. As a result of the distinct orientation of each mode's particle-displacement vector, one mode may react to a critical geologic condition in a more optimal way than do

  19. Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity

    USGS Publications Warehouse

    Frankel, Arthur D.; Stephenson, William J.; Carver, David L.; Williams, Robert A.; Odum, Jack K.; Rhea, Susan

    2007-01-01

    This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source and site dependent amplification factors into a probabilistic seismic hazard calculation. 3D simulations were conducted for the various earthquake sources that can affect Seattle: Seattle fault zone, Cascadia subduction zone, South Whidbey Island fault, and background shallow and deep earthquakes. The maps presented in this document used essentially the same set of faults and distributed-earthquake sources as in the 2002 national seismic hazard maps. The 3D velocity model utilized in the simulations was validated by modeling the amplitudes and waveforms of observed seismograms from five earthquakes in the region, including the 2001 M6.8 Nisqually earthquake. The probabilistic seismic hazard maps presented here depict 1 Hz response spectral accelerations with 10%, 5%, and 2% probabilities of exceedance in 50 years. The maps are based on determinations of seismic hazard for 7236 sites with a spacing of 280 m. The maps show that the most hazardous locations for this frequency band (around 1 Hz) are soft-soil sites (fill and alluvium) within the Seattle basin and along the inferred trace of the frontal fault of the Seattle fault zone. The next highest hazard is typically found for soft-soil sites in the Duwamish Valley south of the Seattle basin. In general, stiff-soil sites in the Seattle basin exhibit higher hazard than stiff-soil sites outside the basin. Sites with shallow bedrock outside the Seattle basin have the lowest estimated hazard for this frequency band.

  20. Planetary subsurface investigation by 3D visualization model .

    NASA Astrophysics Data System (ADS)

    Seu, R.; Catallo, C.; Tragni, M.; Abbattista, C.; Cinquepalmi, L.

    Subsurface data analysis and visualization represents one of the main aspect in Planetary Observation (i.e. search for water or geological characterization). The data are collected by subsurface sounding radars as instruments on-board of deep space missions. These data are generally represented as 2D radargrams in the perspective of space track and z axes (perpendicular to the subsurface) but without direct correlation to other data acquisition or knowledge on the planet . In many case there are plenty of data from other sensors of the same mission, or other ones, with high continuity in time and in space and specially around the scientific sites of interest (i.e. candidate landing areas or particular scientific interesting sites). The 2D perspective is good to analyse single acquisitions and to perform detailed analysis on the returned echo but are quite useless to compare very large dataset as now are available on many planets and moons of solar system. The best way is to approach the analysis on 3D visualization model generated from the entire stack of data. First of all this approach allows to navigate the subsurface in all directions and analyses different sections and slices or moreover navigate the iso-surfaces respect to a value (or interval). The last one allows to isolate one or more iso-surfaces and remove, in the visualization mode, other data not interesting for the analysis; finally it helps to individuate the underground 3D bodies. Other aspect is the needs to link the on-ground data, as imaging, to the underground one by geographical and context field of view.

  1. TOMO3D: 3-D joint refraction and reflection traveltime tomography parallel code for active-source seismic data—synthetic test

    NASA Astrophysics Data System (ADS)

    Meléndez, A.; Korenaga, J.; Sallarès, V.; Miniussi, A.; Ranero, C. R.

    2015-10-01

    We present a new 3-D traveltime tomography code (TOMO3D) for the modelling of active-source seismic data that uses the arrival times of both refracted and reflected seismic phases to derive the velocity distribution and the geometry of reflecting boundaries in the subsurface. This code is based on its popular 2-D version TOMO2D from which it inherited the methods to solve the forward and inverse problems. The traveltime calculations are done using a hybrid ray-tracing technique combining the graph and bending methods. The LSQR algorithm is used to perform the iterative regularized inversion to improve the initial velocity and depth models. In order to cope with an increased computational demand due to the incorporation of the third dimension, the forward problem solver, which takes most of the run time (˜90 per cent in the test presented here), has been parallelized with a combination of multi-processing and message passing interface standards. This parallelization distributes the ray-tracing and traveltime calculations among available computational resources. The code's performance is illustrated with a realistic synthetic example, including a checkerboard anomaly and two reflectors, which simulates the geometry of a subduction zone. The code is designed to invert for a single reflector at a time. A data-driven layer-stripping strategy is proposed for cases involving multiple reflectors, and it is tested for the successive inversion of the two reflectors. Layers are bound by consecutive reflectors, and an initial velocity model for each inversion step incorporates the results from previous steps. This strategy poses simpler inversion problems at each step, allowing the recovery of strong velocity discontinuities that would otherwise be smoothened.

  2. 3D Traveltime Tomography and 1D Wavefield Inversion of Dense 3D Seismic Refraction Data From a Shallow Groundwater Contamination Site

    NASA Astrophysics Data System (ADS)

    Zelt, C. A.; Chen, J.; Levander, A.

    2016-12-01

    In 2012 Rice University carried out a shallow seismic survey in Rifle, Colorado where the groundwater was contaminated by vanadium and uranium ore-processing operations ending in 1958. The purpose of the seismic survey is to provide constraints to improve hydrogeologic modeling. The 3-D P-wave survey over 96 m x 60 m included 2158 shots recorded by 384 channels yielding 828,672 traces. An accelerated weight drop provided data with good signal-to-noise ratio (SNR) and a dominant frequency of 60 Hz. The overall good SNR allows for precise picking and an average uncertainty of 0.65 ms was assigned based on an analysis of all reciprocal time differences. Unreliable source triggering necessitated solving for shot time corrections during travelitme tomography, creating a mixed-parameter inverse problem. Several steps in addition to conventional 3-D traveltime tomography were applied to exploit the dense data and precise picking to overcome the data's low frequency content: (1) stacking the arrival-time-corrected traces in offset bins for 1-D reflectivity modeling to constrain discontinuities; (2) reduced smoothing regularization based on the local angular distribution of raypaths; and (3) a frequency-dependent form of traveltime tomography to account for the data's frequency content. Model assessment techniques include: (1) removal of the best and poorest fit data to assess the effect of outliers, (2) a jackknife procedure to estimate the uncertainty of each velocity node, and (3) checkerboard tests to estimate lateral model resolution using random shot and picking errors consistent with the real data. The results show that most of the velocity model has a relative error of less than 2% and lateral resolution of better than 5, 10 and 20 m to depths of 5, 10 and 20 m, respectively. Results include an isovelocity surface that represents the top of the Wasatch formation.

  3. 3D distribution of seismic anisotropy within the crust beneath Northern Japan

    NASA Astrophysics Data System (ADS)

    Bokelmann, G. H.; Bianchi, I.; Shiomi, K.

    2012-12-01

    Northern Japan is particularly interesting due to frequent earthquakes and the presence of volcanoes. In the past year the attention on this region increased because of the occurrence of the destructive Mw = 8.9-9.0 Tohoku-oki earthquake, on March 11th, 2011. Seismic anisotropy in the crust of Northern Japan has been investigated, but it is not clear yet how much it is related to the tectonic stress, to deformation active on the whole area and whether it is affected by temporal changes. A receiver function data-set was created using teleseisms recorded at 58 seismic stations located in Northern Japan and belonging to the Japanese National (HI-net) network, with the aim of constraining the orientation of anisotropy symmetry axes, the depth of anisotropic layers in the crust, and their relation with the stress field. The harmonic expansion of this data set has been computed up to the second degree and order (k=2). This study focuses on the relative importance of the stress-induced anisotropy (by plate convergence across the subduction zone), and intrinsic characteristics of the rocks. Differences in the orientation of the anisotropic axes at different depth inside the crust, from the surface to the Moho, and lateral variations in the symmetry direction of anisotropic axes are shown. Also we inspect whether there are temporal changes to this pattern.

  4. Thermochemical and phase structure of the D"-Region constrained by 3-D spherical mantle convection and seismic tomography

    NASA Astrophysics Data System (ADS)

    Wu, B.; Olson, P.

    2011-12-01

    Results of time-dependent 3-D spherical mantle convection simulations with Newtonian rheology, solid-state phase transitions, and multiple composition as well as imposed plate motion back to 120 Ma are compared with observed lower mantle seismic heterogeneity to interpret structure in the D"-region. Synthetic seismic tomography images are created from the simulated temperature, composition, and phase change heterogeneity, which are then compared to the global seismic tomography models in terms of pattern and statistical properties. Several models are found that match the seismic tomography in terms of their RMS variation, Gaussian-like frequency distribution, and spherical harmonic degree-2 pattern for global-scale low velocity and high velocity regions. For these best-fitting models the heat flow at the CMB and the mantle heat flow at the surface are about 13.1 ~ 14.7 TW and 31 TW, respectively, and the Urey ratio is in range of 0.36 ~ 0.58. 3-D mantle convection constrained by plate motion history explains the statistics and the global pattern of lower mantle seismic heterogeneity provided that thermal, chemical and phase change heterogeneity is included in the mantle D"-region, and predicts large temporal and spatial variations in heat transport across the CMB.

  5. Toward developing a 3D seismic velocity model beneath the SE Tibetan and surrounding regions

    NASA Astrophysics Data System (ADS)

    Sun, Ya; Liu, Jianxin; Niu, Fenglin

    2014-05-01

    We investigated crustal and lithospheric mantle seismic structure beneath the southeast of the Tibetan plateau and the surrounding regions to understand what roles the lower crust and lithospheric mantle have played in shaping area. Firstly, we analyzed receiver function data that were recorded by four provincial seismic networks of the China Earthquake Administration, comprising of 88 broadband stations in the study area, from earthquakes occurring from July 2007 to July 2010. We have employed a new analysis technique for estimating crustal anisotropy and found significant seismic anisotropy with the splitting time of 0.3-0.8s beneath the SE margin of the Tibetan plateau. Both the splitting time and the fast direction were comparable to the result from the SKS/SKKS data, suggesting that crustal anisotropy is the main cause of shear wave splitting of the SKS/SKKS wave. On the other hand, stations located within the surrounding regions, Sichuan, Guizhou and Yunnan showed very little or no crustal anisotropy. However, SKS splitting data showed a sharp change of fast direction from NS in the north to EW in the south between 27° N and 25° N near the YuiGui plateau. This sharp transition was not observed from our crustal anisotropic result, suggesting that the crust and lithospheric mantle have different deformation pattern in this area. Secondly, we applied the finite frequency tomography method to map the upper mantle tomography beneath SE Tibetan plateau, the image show some fast S wave velocity anomalies beneath the SE margin of Tibet with the depth varying from ~90km to 350km, which also identified the decoupled structure between lower crust and lithospheric mantle beneath the SE Tibet margin. Once the crustal anisotropic fast polarization direction was identified, we applied the H-k analysis to determine the crustal thickness and two Vp/Vs ratios corresponding to the fast and slow propagating directions. We found significant difference between the plateau and

  6. Development of a State-Wide 3-D Seismic Tomography Velocity Model for California

    NASA Astrophysics Data System (ADS)

    Thurber, C. H.; Lin, G.; Zhang, H.; Hauksson, E.; Shearer, P.; Waldhauser, F.; Hardebeck, J.; Brocher, T.

    2007-12-01

    We report on progress towards the development of a state-wide tomographic model of the P-wave velocity for the crust and uppermost mantle of California. The dataset combines first arrival times from earthquakes and quarry blasts recorded on regional network stations and travel times of first arrivals from explosions and airguns recorded on profile receivers and network stations. The principal active-source datasets are Geysers-San Pablo Bay, Imperial Valley, Livermore, W. Mojave, Gilroy-Coyote Lake, Shasta region, Great Valley, Morro Bay, Mono Craters-Long Valley, PACE, S. Sierras, LARSE 1 and 2, Loma Prieta, BASIX, San Francisco Peninsula and Parkfield. Our beta-version model is coarse (uniform 30 km horizontal and variable vertical gridding) but is able to image the principal features in previous separate regional models for northern and southern California, such as the high-velocity subducting Gorda Plate, upper to middle crustal velocity highs beneath the Sierra Nevada and much of the Coast Ranges, the deep low-velocity basins of the Great Valley, Ventura, and Los Angeles, and a high- velocity body in the lower crust underlying the Great Valley. The new state-wide model has improved areal coverage compared to the previous models, and extends to greater depth due to the data at large epicentral distances. We plan a series of steps to improve the model. We are enlarging and calibrating the active-source dataset as we obtain additional picks from investigators and perform quality control analyses on the existing and new picks. We will also be adding data from more quarry blasts, mainly in northern California, following an identification and calibration procedure similar to Lin et al. (2006). Composite event construction (Lin et al., in press) will be carried out for northern California for use in conventional tomography. A major contribution of the state-wide model is the identification of earthquakes yielding arrival times at both the Northern California Seismic

  7. Influence of Poroelasticity on the 3D Seismic Response of Complex Geological Media

    NASA Astrophysics Data System (ADS)

    Wuttke, Frank; Dineva, Petia; Fontara, Ioanna-Kleoniki

    2017-06-01

    Elastic wave propagation in 3D poroelastic geological media with localized heterogeneities, such as an elastic inclusion and a canyon is investigated to visualize the modification of local site responses under consideration of water saturated geomaterial. The extended computational environment herein developed is a direct Boundary Integral Equation Method (BIEM), based on the frequency-dependent fundamental solution of the governing equation in poro-visco elastodynamics. Bardet's model is introduced in the analysis as the computationally efficient viscoelastic isomorphism to Biot's equations of dynamic poroelasticity, thus replacing the two-phase material by a complex valued single-phase one. The potential of Bardet's analogue is illustrated for low frequency vibrations and all simulation results demonstrate the dependency of wave field developed along the free surface on the properties of the soil material.

  8. 3D Shear Wave Velocity Structure and Seismic Anisotropy beneath Northern Tibet

    NASA Astrophysics Data System (ADS)

    Ceylan, S.; Ni, J. F.; Chen, Y. J.; Tilmann, F.; Yang, Y.; Ritzwoller, M. H.; Sandvol, E. A.

    2010-12-01

    Recent studies have revealed that uplift of the Tibetan plateau may be related to removal of lithospheric mantle and resulting emplacement of hotter, less dense asthenospheric material. In addition to these modes of deformation, other studies have proposed that plateau uplift and crustal thickening have occurred through a process of lateral crustal flow. In order to study the evolution and continental dynamics of the Tibetan plateau, we deployed 74 broadband seismic stations throughout northern Tibet. We have measured the fundamental mode Rayleigh wave phase velocities using the two plane wave approach for periods between 20-143 seconds and verified our results utilizing a two station method. Similar to the fast directions obtained from teleseismic shear wave splitting, our measurements indicate significant (>2%) azimuthal anisotropy throughout the upper mantle down to depths exceeding 250 km, with a dominantly east-west fast direction. Although we observe some variations in fast directions with depth, they are generally consistent (i.e., within 15 degrees). Furthermore, we observe a correlation between fast directions and strikes of major fault zones that may be indicative of vertically coherent deformation within the mantle. Our 3D tomographic models show an uppermost mantle low velocity zone north of Bangong-Nujiang Suture (BNS) in northern Tibet, and a high velocity anomaly extending ~200 km centered on BNS. We suspect that the low velocity zone is due to warmer and thinner lithosphere in the northern Qiangtang and Songpan-Gonzi terranes. At depth, we observe high velocity bodies to the south both in our phase velocity and shear wave velocity maps, possibly indicative of underthrusting Indian lithosphere. Further, high velocity bodies weaken with decreasing depth, which could be alternatively interpreted as delaminating Asian lithosphere. Shear-wave velocities and dispersion curves for northern Tibet are lower than those of Southern Tibet at depths ~80-190 km

  9. Selectivity of seismic electric signal (SES) of the 2000 Izu earthquake swarm: a 3D FEM numerical simulation model.

    PubMed

    Huang, Qinghua; Lin, Yufeng

    2010-01-01

    Although seismic electric signal (SES) has been used for short-term prediction of earthquakes, selectivity of SES still remains as one of the mysterious features. As a case study, we made a numerical simulation based on a 3D finite element method (FEM) on the selectivity of SES observed in the case of the 2000 Izu earthquake swarm. Our numerical results indicated that the existence of conductive channel under Niijima island could explain the reported SES selectivity.

  10. Selectivity of seismic electric signal (SES) of the 2000 Izu earthquake swarm: a 3D FEM numerical simulation model

    PubMed Central

    Huang, Qinghua; Lin, Yufeng

    2010-01-01

    Although seismic electric signal (SES) has been used for short-term prediction of earthquakes, selectivity of SES still remains as one of the mysterious features. As a case study, we made a numerical simulation based on a 3D finite element method (FEM) on the selectivity of SES observed in the case of the 2000 Izu earthquake swarm. Our numerical results indicated that the existence of conductive channel under Niijima island could explain the reported SES selectivity. PMID:20228625

  11. Characterization of fracture reservoirs using static and dynamic data: From sonic and 3D seismic to permeability distribution. Annual report, March 1, 1996--February 28, 1997

    SciTech Connect

    Parra, J.O.; Collier, H.A.; Owen, T.E.

    1997-06-01

    In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. They also may connect the borehole to remote zones of better reservoir characteristics. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based on the effects of such conditions on the propagation of acoustic and seismic waves in the rock. The project is a study directed toward the evaluation of acoustic logging and 3D-seismic measurement techniques as well as fluid flow and transport methods for mapping permeability anisotropy and other petrophysical parameters for the understanding of the reservoir fracture systems and associated fluid dynamics. The principal application of these measurement techniques and methods is to identify and investigate the propagation characteristics of acoustic and seismic waves in the Twin Creek hydrocarbon reservoir owned by Union Pacific Resources (UPR) and to characterize the fracture permeability distribution using production data. This site is located in the overthrust area of Utah and Wyoming. UPR drilled six horizontal wells, and presently UPR has two rigs running with many established drill hole locations. In addition, there are numerous vertical wells that exist in the area as well as 3D seismic surveys. Each horizontal well contains full FMS logs and MWD logs, gamma logs, etc.

  12. Characterization of gas hydrate distribution using conventional 3D seismic data in the Pearl River Mouth Basin, South China Sea

    USGS Publications Warehouse

    Wang, Xiujuan; Qiang, Jin; Collett, Timothy S.; Shi, Hesheng; Yang, Shengxiong; Yan, Chengzhi; Li, Yuanping; Wang, Zhenzhen; Chen, Duanxin

    2016-01-01

    A new 3D seismic reflection data volume acquired in 2012 has allowed for the detailed mapping and characterization of gas hydrate distribution in the Pearl River Mouth Basin in the South China Sea. Previous studies of core and logging data showed that gas hydrate occurrence at high concentrations is controlled by the presence of relatively coarse-grained sediment and the upward migration of thermogenic gas from the deeper sediment section into the overlying gas hydrate stability zone (BGHSZ); however, the spatial distribution of the gas hydrate remains poorly defined. We used a constrained sparse spike inversion technique to generate acoustic-impedance images of the hydrate-bearing sedimentary section from the newly acquired 3D seismic data volume. High-amplitude reflections just above the bottom-simulating reflectors (BSRs) were interpreted to be associated with the accumulation of gas hydrate with elevated saturations. Enhanced seismic reflections below the BSRs were interpreted to indicate the presence of free gas. The base of the BGHSZ was established using the occurrence of BSRs. In areas absent of well-developed BSRs, the BGHSZ was calculated from a model using the inverted P-wave velocity and subsurface temperature data. Seismic attributes were also extracted along the BGHSZ that indicate variations reservoir properties and inferred hydrocarbon accumulations at each site. Gas hydrate saturations estimated from the inversion of acoustic impedance of conventional 3D seismic data, along with well-log-derived rock-physics models were also used to estimate gas hydrate saturations. Our analysis determined that the gas hydrate petroleum system varies significantly across the Pearl River Mouth Basin and that variability in sedimentary properties as a product of depositional processes and the upward migration of gas from deeper thermogenic sources control the distribution of gas hydrates in this basin.

  13. Computer power fathoms the depths: billion-bit data processors illuminate the subsurface. [3-D Seismic techniques

    SciTech Connect

    Ross, J.J.

    1985-01-01

    Some of the same space-age signal technology being used to track events 200 miles above the earth is helping petroleum explorationists track down oil and natural gas two miles and more down into the earth. The breakthroughs, which have come in a technique called three-dimensional seismic work, could change the complexion of exploration for oil and natural gas. Thanks to this 3-D seismic approach, explorationists can make dynamic maps of sites miles beneath the surface. Then explorationists can throw these maps on space-age computer systems and manipulate them every which way - homing in sharply on salt domes, faults, sands and traps associated with oil and natural gas. ''The 3-D seismic scene has exploded within the last two years,'' says, Peiter Tackenberg, Marathon technical consultant who deals with both domestic and international exploration. The 3-D technique has been around for more than a decade, he notes, but recent achievements in space-age computer hardware and software have unlocked its full potential.

  14. Seismic moment tensor inversion using 3D velocity model and its application to the 2013 Lushan earthquake sequence

    NASA Astrophysics Data System (ADS)

    Zhu, Lupei; Zhou, Xiaofeng

    2016-10-01

    Source inversion of small-magnitude events such as aftershocks or mine collapses requires use of relatively high frequency seismic waveforms which are strongly affected by small-scale heterogeneities in the crust. In this study, we developed a new inversion method called gCAP3D for determining general moment tensor of a seismic source using Green's functions of 3D models. It inherits the advantageous features of the "Cut-and-Paste" (CAP) method to break a full seismogram into the Pnl and surface-wave segments and to allow time shift between observed and predicted waveforms. It uses grid search for 5 source parameters (relative strengths of the isotropic and compensated-linear-vector-dipole components and the strike, dip, and rake of the double-couple component) that minimize the waveform misfit. The scalar moment is estimated using the ratio of L2 norms of the data and synthetics. Focal depth can also be determined by repeating the inversion at different depths. We applied gCAP3D to the 2013 Ms 7.0 Lushan earthquake and its aftershocks using a 3D crustal-upper mantle velocity model derived from ambient noise tomography in the region. We first relocated the events using the double-difference method. We then used the finite-differences method and reciprocity principle to calculate Green's functions of the 3D model for 20 permanent broadband seismic stations within 200 km from the source region. We obtained moment tensors of the mainshock and 74 aftershocks ranging from Mw 5.2 to 3.4. The results show that the Lushan earthquake is a reverse faulting at a depth of 13-15 km on a plane dipping 40-47° to N46° W. Most of the aftershocks occurred off the main rupture plane and have similar focal mechanisms to the mainshock's, except in the proximity of the mainshock where the aftershocks' focal mechanisms display some variations.

  15. An open-source Matlab code package for improved rank-reduction 3D seismic data denoising and reconstruction

    NASA Astrophysics Data System (ADS)

    Chen, Yangkang; Huang, Weilin; Zhang, Dong; Chen, Wei

    2016-10-01

    Simultaneous seismic data denoising and reconstruction is a currently popular research subject in modern reflection seismology. Traditional rank-reduction based 3D seismic data denoising and reconstruction algorithm will cause strong residual noise in the reconstructed data and thus affect the following processing and interpretation tasks. In this paper, we propose an improved rank-reduction method by modifying the truncated singular value decomposition (TSVD) formula used in the traditional method. The proposed approach can help us obtain nearly perfect reconstruction performance even in the case of low signal-to-noise ratio (SNR). The proposed algorithm is tested via one synthetic and field data examples. Considering that seismic data interpolation and denoising source packages are seldom in the public domain, we also provide a program template for the rank-reduction based simultaneous denoising and reconstruction algorithm by providing an open-source Matlab package.

  16. Fluid Flow Processes Study: from a 3D seismic data set in the Pointer Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Han, Wei-Chung; Liu, Char-Shine; Chen, Liwen; Chi, Wu-Cheng; Lin, Che-Chuan

    2016-04-01

    This study analyzes a 3D seismic cube in the Pointer Ridge for understanding the fluid flow processes in subsurface. Pointer Ridge is a ridge situated on the passive China continental margin and is suggested as a potential prospect for future gas hydrate development. High methane flux rate, active gas venting and seismic chimneys have been observed in this area, which are direct evidences for active ongoing fluid migration processes. To find the possible fluid conduits and to understand how the fluids have migrated along those conduits, we firstly identify the structural and sedimentary features from this 3D seismic cube in our study area. Secondly, seismic attribute analyses are carried out for detecting fluid conduits and evaluating the contribution of recognized faults/fractures for fluid flow, respectively. Finally, we propose conceptual models to illustrate how fluids have migrated along those conduits to the seafloor and how those conduits have developed. The results show: 1) a major NE-SW striking normal fault (PR Fault) separates a depositional field on the hanging wall and a erosional field on the footwall; 2) the PR Fault zone itself and the chimneys in its footwall act as main conduits for focused fluid flow migrating to the seafloor; 3) the development of the chimneys in the Pointer Ridge area are highly controlled by the erosion and deposition processes. Since the ongoing fluid flow processes will increase the seafloor instabilities and the Pointer Ridge is a gas hydrate leaking site, our results could provide useful information for further risk evaluation.

  17. High-resolution 3-D P wave attenuation structure of the New Madrid Seismic Zone using local earthquake tomography

    NASA Astrophysics Data System (ADS)

    Bisrat, Shishay T.; DeShon, Heather R.; Pesicek, Jeremy; Thurber, Clifford

    2014-01-01

    A three-dimensional (3-D), high-resolution P wave seismic attenuation model for the New Madrid Seismic Zone (NMSZ) is determined using P wave path attenuation (t*) values of small-magnitude earthquakes (MD < 3.9). Events were recorded at 89 broadband and short-period seismometers of the Cooperative New Madrid Seismic Zone Network and 40 short-period seismometers of the Portable Array for Numerical Data Acquisition experiment. The amplitude spectra of all the earthquakes are simultaneously inverted for source, path (t*), and site parameters. The t* values are inverted for QP using local earthquake tomography methods and a known 3-D P wave velocity model for the region. The four major seismicity arms of the NMSZ exhibit reduced QP (higher attenuation) than the surrounding crust. The highest attenuation anomalies coincide with areas of previously reported high swarm activity attributed to fluid-rich fractures along the southeast extension of the Reelfoot fault. The QP results are consistent with previous attenuation studies in the region, which showed that active fault zones and fractured crust in the NMSZ are highly attenuating.

  18. Seismic body-wave interferometry using noise autocorrelations for crustal structure and a tutorial on 3D seismic processing and imaging using Madagascar

    NASA Astrophysics Data System (ADS)

    Olejnik, Peter

    Seismic body-wave interferometry is applied to selected seismic stations from the USArray Earthscope Transportable Array (TA) by autocorrelating ambient seismic noise recordings to construct effective zero-offset reflection seismograms. The robustness of the auto-correlations of noise traces is first tested on a TA station in Nevada where body-wave reflections similar to those found in an earlier study are identified. This approach is then applied to several TA stations in the central U.S., and the results are compared with synthetic data. Different stacking time periods are then examined to find the shortest time intervals that provide stable correlation stacks. A tutorial on 3D seismic processing and imaging using the Madagascar open-source software package is next presented for educational purposes. The 3D Teapot Dome seismic data set is examined to illustrate the processing and imaging steps. A number of processing steps are applied to the data set, including amplitude gaining, muting, deconvolution, static corrections, velocity analysis, normal moveout (NMO) correction, and stacking. Post-stack time and depth migrations are then performed on the stacked data along with post-migration f-x deconvolution.

  19. Joint inversion of 3-D seismic, gravimetric and magnetotelluric data for sub-basalt imaging in the Faroe-Shetland Basin

    NASA Astrophysics Data System (ADS)

    Heincke, B.; Moorkamp, M.; Jegen, M.; Hobbs, R. W.

    2012-12-01

    Imaging of sub-basalt sediments with reflection seismic techniques is limited due to absorption, scattering and transmission effects and the presence of peg-leg multiples. Although many of the difficulties facing conventional seismic profiles can be overcome by recording long offset data resolution of sub-basalt sediments in seismic sections is typically still largely restricted. Therefore multi-parametric approaches in general and joint inversion strategies in particular (e.g. Colombo et al., 2008, Jordan et al., 2012) are considered as alternative to gain additional information from sub-basalt structures. Here, we combine in a 3-D joint inversion first-arrival time tomography, FTG gravity and MT data to identify the base basalt and resolve potential sediments underneath. For sub-basalt exploration the three methods complement each other such that the null space is reduced and significantly better resolved models can be obtained than would be possible by the individual methods: The seismic data gives a robust model for the supra-basalt sediments whilst the gravity field is dominated by the high density basalt and basement features. The MT on the other hand is sensitive to the conductivity in both the supra- and sub-basalt sediments. We will present preliminary individual and joint inversion result for a FTG, seismic and MT data set located in the Faroe-Shetland basin. Because the investigated area is rather large (~75 x 40 km) and the individual data sets are relatively huge, we use a joint inversion framework (see Moorkamp et al., 2011) which is designed to handle large amount of data/model parameters. This program has moreover the options to link the individual parameter models either petrophysically using fixed parameter relationships or structurally using the cross-gradient approach. The seismic data set consists of a pattern of 8 intersecting wide-angle seismic profiles with maximum offsets of up to ~24 km. The 3-D gravity data set (size :~ 30 x 30 km) is

  20. Segmentation of Hypocenters and 3-D Velocity Structure around the Kii Peninsula Revealed by Onshore and Offshore Seismic Observations

    NASA Astrophysics Data System (ADS)

    Akuhara, T.; Mochizuki, K.; Nakahigashi, K.; Yamada, T.; Shinohara, M.; Sakai, S.; Kanazawa, T.; Uehira, K.; Shimizu, H.

    2013-12-01

    The Philippine Sea Plate subducts beneath the Eurasian Plate at a rate of ~4 cm/year along the Nankai Trough, southwest of Japan. Around the Kii Peninsula, the rupture boundary of the historical Tonankai and Nankai large earthquakes is located, and previous researches have revealed along-strike segmentation of hypocenters [Mochizuki et al., 2010], P-wave anisotropy [Ishise et al., 2009], low frequency earthquake (LFE) distribution [e.g., Obara, 2010] and subduction depth of the Philippine Sea (PHS) Plate, or there may exist a split in the PHS Plate [Ide et al., 2010]. To investigate such segmentation, in our previous work we determined 3-D velocity structure and hypocenters using P- and S-wave arrival times of earthquakes recorded by both ocean bottom seismometers (OBSs) that were deployed from 2003 to 2007 and on-land stations [Akuhara et al., 2013]. As a result, it was discovered that Vp/Vs ratio is also segmented within the oceanic crust and at the bottom of the overriding plate, which coincides with the LFE distribution: segment A is located along the Kii Channel, segment B around the western Kii Peninsula, and segment C around the eastern Kii Peninsula. In segment B, Vp/Vs ratio is low within the oceanic crust and LFE cluster characterized by an anomalously small amount of cumulative slip, compared to the other LFE clusters around the Kii Peninsula, is located [Obara, 2010]. The difference of Vp/Vs ratio and LFE activity among segments were interpreted as difference of pore fluid pressure. In fact, similar segmentation can be seen in hypocenters: Segment A with concentrated seismicity in the oceanic mantle, segment B with that in the oceanic crust, and segment C with little seismicity. To derive characteristic patterns of the hypocenters, we conducted a cluster analysis of earthquakes based on waveform similarity represented by cross-correlation coefficients (CCs) [e.g., Cattaneo, 1999], in which we took varying structural site effects among the OBS stations

  1. 3D joint inversion using seismic data and marine controlled-source electromagnetic data for evaluating gas hydrate concentrations

    NASA Astrophysics Data System (ADS)

    Kim, B.; Byun, J.; Seol, S. J.; Jeong, S.; Chung, Y.; Kwon, T.

    2015-12-01

    For many decades, gas hydrates have been received great attention as a potential source of natural gas. Therefore, the detailed information of structures of buried gas hydrates and their concentrations are prerequisite for the production for the gas hydrate as a reliable source of alternate energy. Recently, for this reason, a lot of gas hydrate assessment methods have been proposed by many researchers. However, it is still necessary to establish as new method for the further improvement of the accuracy of the 3D gas hydrate distribution. In this study, we present a 3D joint inversion method that provides superior quantitative information of gas hydrate distributions using 3D seismic data obtained by ocean-bottom cable (OBC) and marine controlled-source electromagnetic (CSEM) data. To verify our inversion method, we first built the general 3D gas hydrate model containing vertical methane-flow pathways. With the described model, we generated synthetic 3D OBC data and marine CSEM data using finite element modeling algorithms, respectively. In the joint inversion process, to obtain the high-resolution volumetric P-wave velocity structure, we applied the 3D full waveform inversion algorithm to the acquired OBC data. After that, the obtained P-wave velocity model is used as the structure constraint to compute cross-gradients with the updated resistivity model in the EM inversion process. Finally, petrophysical relations were applied to estimate volumetric gas hydrate concentrations. The proposed joint inversion process makes possible to obtain more precise quantitative gas hydrate assessment than inversion processes using only seismic or EM data. This technique can be helpful for accurate decision-making in gas hydrate development as well as in their production monitoring.

  2. Next-generation seismic experiments - II: wide-angle, multi-azimuth, 3-D, full-waveform inversion of sparse field data

    NASA Astrophysics Data System (ADS)

    Morgan, Joanna; Warner, Michael; Arnoux, Gillean; Hooft, Emilie; Toomey, Douglas; VanderBeek, Brandon; Wilcock, William

    2016-02-01

    3-D full-waveform inversion (FWI) is an advanced seismic imaging technique that has been widely adopted by the oil and gas industry to obtain high-fidelity models of P-wave velocity that lead to improvements in migrated images of the reservoir. Most industrial applications of 3-D FWI model the acoustic wavefield, often account for the kinematic effect of anisotropy, and focus on matching the low-frequency component of the early arriving refractions that are most sensitive to P-wave velocity structure. Here, we have adopted the same approach in an application of 3-D acoustic, anisotropic FWI to an ocean-bottom-seismometer (OBS) field data set acquired across the Endeavour oceanic spreading centre in the northeastern Pacific. Starting models for P-wave velocity and anisotropy were obtained from traveltime tomography; during FWI, velocity is updated whereas anisotropy is kept fixed. We demonstrate that, for the Endeavour field data set, 3-D FWI is able to recover fine-scale velocity structure with a resolution that is 2-4 times better than conventional traveltime tomography. Quality assurance procedures have been employed to monitor each step of the workflow; these are time consuming but critical to the development of a successful inversion strategy. Finally, a suite of checkerboard tests has been performed which shows that the full potential resolution of FWI can be obtained if we acquire a 3-D survey with a slightly denser shot and receiver spacing than is usual for an academic experiment. We anticipate that this exciting development will encourage future seismic investigations of earth science targets that would benefit from the superior resolution offered by 3-D FWI.

  3. Crustal density structure in northwestern South America derived from analysis and 3-D modeling of gravity and seismicity data

    NASA Astrophysics Data System (ADS)

    Sanchez-Rojas, J.; Palma, M.

    2014-11-01

    This paper presents a three-dimensional (3-D) interpretation of new gravity and seismicity datasets for northern South America. A 3-D forward density model was constructed on the basis of deep wide-angle seismic refraction sections, Moho depth from receiver functions, and surface geology. Density values were estimated from published borehole data for sediments by using empirical velocity-density functions and considering mineralogical-chemical composition variations under typical pressure-temperature conditions for upper and lower crustal rocks. The modeled 3-D density structure was kept as simple as possible. The continental and oceanic plates were formed by two sedimentary bodies, one crustal body, and one mantle lithosphere body overlying a sub-lithospheric mantle. The Caribbean plate was modeled with an atypical crustal thickness of ~ 18 km (including sediments). The geometry of the Caribbean plate was modeled using a combination of gravity modeling and analyses of the seismicity and focal-mechanism solutions. Intermediate seismicity and the orientation of the T-axes appeared aligned along the predicted position of the slab. As a result, the estimated slab dip angle under Maracaibo and the Mérida Andes was ~ 15° and increases up to ~ 20° after 100 km depth. The model shows two orientations in the slab strike: ~ N150°E ± 5 in western Colombia and southward underneath the Maracaibo block. The modeling results suggest that the northern South American upper and lower crusts are relatively light and the density of the Caribbean crust is typical for an oceanic crust.

  4. High-resolution seismic mapping at a groundwater contamination site: 3-D traveltime tomography of refraction data

    NASA Astrophysics Data System (ADS)

    Azaria, A.; Zelt, C.; Levander, A.

    2003-04-01

    As part of an ongoing environmental characterization project at Hill Air Force Base near Ogden, Utah, a 3-D seismic survey led by a team from Rice University was performed over a contaminated aquifer in 2000. This site contains significant amounts of dense non-aqueous phase liquids (DNAPLs) in a shallow aquifer less than ~15 m deep. The aquifer is bounded below by a clay aquiclude, in which a paleochannel acts as a trap for the contaminants. The overburden consists of Quaternary sands, gravels and clays. Imaging the structure of the paleochannel at depths up to 15 m is the main target of the survey. The four week experiment included 3-D reflection, 3-D refraction, checkshot surveys and vertical seismic profiles using wells up to 15m deep. Here we present traveltime tomography results from the 3-D refraction survey which consisted of 596 RefTek Texan recorders deployed uniformly in a stationary rectangular grid over an area of 95m by 36m. A shot from a .223 caliber rifle was fired 30cm from each receiver station, yielding a dataset with about 360,000 traces. The arrival times of the refracted waves were used in a 3-D tomographic inversion to image the seismic velocity structure of the study area. The iterative, nonlinear tomographic approach employs regularization to smooth the model perturbations with respect to a simple 1-D starting/reference model. The resulting velocity model shows that the near-surface velocity increases by roughly a factor of 5 in the upper 15m, from about 300m/s to 1500m/s. Cross-sections through the model show a north-south trending low-velocity feature interpreted to be the channel structure. The low-velocity feature is best viewed via depth slices which define an anomaly that roughly outlines the geometry of the buried paleo-channel based on well data. A comparison between the 3-D velocity model and time slices through a brute stack of the 3-D reflection data also show close agreement (see Dana et al. this session). Checkerboard tests

  5. Determination of porosity and facies trends in a complex carbonate reservoir, by using 3-D seismic, borehole tools, and outcrop geology

    SciTech Connect

    Zacharakis, T.G. Jr.; Comet, J.N.; Murillo, A.A.

    1996-08-01

    Mesozoic carbonate reservoirs are found in the Mediterranean Sea, off the east coast of Spain. A wide variation of porosities are found in the core samples and logs: vuggy, breccia, fractures, and cavern porosity. In addition, complex Tertiary carbonate geometries include olistostromes, breccia bodies, and reef buildups, which are found on top of Mesozoic carbonates. Predicting the porosity trends within these oil productive reservoirs requires an understanding of how primary porosity was further enhanced by secondary processes, including fractures, karstification, and dolomitization in burial conditions. Through an extensive investigation of field histories, outcrop geology, and seismic data, a series of basic reservoir styles have been identified and characterized by well log signature and seismic response. The distribution pattern of the different reservoirs styles is highly heterogeneous, but by integrating subsurface data and outcrop analogs, it is possible to distinguish field-scale and local patterns of both vertical and local variations in reservoir properties. Finally, it is important to quantify these reservoir properties through the study of seismic attributes, such as amplitude variations, and log responses at the reservoir interval. By incorporating 3-D seismic data, through the use of seismic inversion, it is possible to predict porosity trends. Further, the use of geostatistics can lead to the prediction of reservoir development within the carbonate facies.

  6. 3D shear-wave velocity structure of the eastern Tennessee seismic zone from ambient noise correlation data

    NASA Astrophysics Data System (ADS)

    Arroucau, Pierre; Kuponiyi, Ayodeji; Vlahovic, Gordana; Powell, Chris

    2013-04-01

    The Eastern Tennessee Seismic Zone (ETSZ) is an intraplate seismic region characterized by frequent but low magnitude earthquakes and is the second most active seismic area in the United States east of the Rocky Mountains. One key question in the ETSZ is the actual relationship between earthquake distribution and geological structure at depth. Seismicity is mostly confined in the Precambrian basement, below the Paleozoic cover of the southern Appalachian foreland fold-and-thrust belt and shows little to no correlation with surface geological features. Since the middle of the seventies, the Center for Earthquake Research and Information (CERI) has installed and maintained several seismic networks in central and eastern United States. In this work, we use Rayleigh wave group and phase velocity dispersion information obtained from cross-correlation of seismic ambient noise at 24 short-period stations located in the vicinity of the ETSZ. The 3D velocity structure is estimated in four steps. First, dispersion curves are obtained for simultaneously recording station pairs for periods ranging from 2 to 20 s. Then, 2D group and phase velocity maps are determined for each period. Those maps are further used to reconstruct dispersion curves at fixed, regularly spaced locations. For each of these locations, a 1D shear-wave velocity profile is finally inverted for, that takes velocity information from previous studies into account. By providing new information about the upper crustal structure of this region, this work is a contribution to the understanding of the seismic activity of the ETSZ, and -to a broader extent- of the structure and evolution of the North American lithosphere.

  7. Capabilities of seismic and georadar 2D/3D imaging of shallow subsurface of transport route using the Seismobile system

    NASA Astrophysics Data System (ADS)

    Pilecki, Zenon; Isakow, Zbigniew; Czarny, Rafał; Pilecka, Elżbieta; Harba, Paulina; Barnaś, Maciej

    2017-08-01

    In this work, the capabilities of the Seismobile system for shallow subsurface imaging of transport routes, such as roads, railways, and airport runways, in different geological conditions were presented. The Seismobile system combines the advantages of seismic profiling using landstreamer and georadar (GPR) profiling. It consists of up to four seismic measuring lines and carriage with a suspended GPR antenna. Shallow subsurface recognition may be achieved to a maximum width of 10.5 m for a distance of 3.5 m between the measurement lines. GPR measurement is performed in the axis of the construction. Seismobile allows the measurement time, labour and costs to be reduced due to easy technique of its installation, remote data transmission from geophones to accompanying measuring modules, automated location of the system based on GPS and a highly automated method of seismic wave excitation. In this paper, the results of field tests carried out in different geological conditions were presented. The methodologies of acquisition, processing and interpretation of seismic and GPR measurements were broadly described. Seismograms and its spectrum registered by Seismobile system were compared to the ones registered by Geode seismograph of Geometrix. Seismic data processing and interpretation software allows for the obtaining of 2D/3D models of P- and S-wave velocities. Combined seismic and GPR results achieved sufficient imaging of shallow subsurface to a depth of over a dozen metres. The obtained geophysical information correlated with geological information from the boreholes with good quality. The results of performed tests proved the efficiency of the Seismobile system in seismic and GPR imaging of a shallow subsurface of transport routes under compound conditions.

  8. Application of Cutting-Edge 3D Seismic Attribute Technology to the Assessment of Geological Reservoirs for CO2 Sequestration

    SciTech Connect

    Christopher Liner; Jianjun Zeng; Po Geng Heather King Jintan Li; Jennifer Califf; John Seales

    2010-03-31

    The goals of this project were to develop innovative 3D seismic attribute technologies and workflows to assess the structural integrity and heterogeneity of subsurface reservoirs with potential for CO{sub 2} sequestration. Our specific objectives were to apply advanced seismic attributes to aide in quantifying reservoir properies and lateral continuity of CO{sub 2} sequestration targets. Our study area is the Dickman field in Ness County, Kansas, a type locality for the geology that will be encountered for CO{sub 2} sequestration projects from northern Oklahoma across the U.S. midcontent to Indiana and beyond. Since its discovery in 1962, the Dickman Field has produced about 1.7 million barrels of oil from porous Mississippian carbonates with a small structural closure at about 4400 ft drilling depth. Project data includes 3.3 square miles of 3D seismic data, 142 wells, with log, some core, and oil/water production data available. Only two wells penetrate the deep saline aquifer. Geological and seismic data were integrated to create a geological property model and a flow simulation grid. We systematically tested over a dozen seismic attributes, finding that curvature, SPICE, and ANT were particularly useful for mapping discontinuities in the data that likely indicated fracture trends. Our simulation results in the deep saline aquifer indicate two effective ways of reducing free CO{sub 2}: (a) injecting CO{sub 2} with brine water, and (b) horizontal well injection. A tuned combination of these methods can reduce the amount of free CO{sub 2} in the aquifer from over 50% to less than 10%.

  9. Reducing Disk Storage of Full-3D Seismic Waveform Tomography (F3DT) Through Lossy Online Compression

    SciTech Connect

    Lindstrom, Peter; Chen, Po; Lee, En-Jui

    2016-05-05

    Full-3D seismic waveform tomography (F3DT) is the latest seismic tomography technique that can assimilate broadband, multi-component seismic waveform observations into high-resolution 3D subsurface seismic structure models. The main drawback in the current F3DT implementation, in particular the scattering-integral implementation (F3DT-SI), is the high disk storage cost and the associated I/O overhead of archiving the 4D space-time wavefields of the receiver- or source-side strain tensors. The strain tensor fields are needed for computing the data sensitivity kernels, which are used for constructing the Jacobian matrix in the Gauss-Newton optimization algorithm. In this study, we have successfully integrated a lossy compression algorithm into our F3DT SI workflow to significantly reduce the disk space for storing the strain tensor fields. The compressor supports a user-specified tolerance for bounding the error, and can be integrated into our finite-difference wave-propagation simulation code used for computing the strain fields. The decompressor can be integrated into the kernel calculation code that reads the strain fields from the disk and compute the data sensitivity kernels. During the wave-propagation simulations, we compress the strain fields before writing them to the disk. To compute the data sensitivity kernels, we read the compressed strain fields from the disk and decompress them before using them in kernel calculations. Experiments using a realistic dataset in our California statewide F3DT project have shown that we can reduce the strain-field disk storage by at least an order of magnitude with acceptable loss, and also improve the overall I/O performance of the entire F3DT-SI workflow significantly. The integration of the lossy online compressor may potentially open up the possibilities of the wide adoption of F3DT-SI in routine seismic tomography practices in the near future.

  10. Reducing disk storage of full-3D seismic waveform tomography (F3DT) through lossy online compression

    NASA Astrophysics Data System (ADS)

    Lindstrom, Peter; Chen, Po; Lee, En-Jui

    2016-08-01

    Full-3D seismic waveform tomography (F3DT) is the latest seismic tomography technique that can assimilate broadband, multi-component seismic waveform observations into high-resolution 3D subsurface seismic structure models. The main drawback in the current F3DT implementation, in particular the scattering-integral implementation (F3DT-SI), is the high disk storage cost and the associated I/O overhead of archiving the 4D space-time wavefields of the receiver- or source-side strain tensors. The strain tensor fields are needed for computing the data sensitivity kernels, which are used for constructing the Jacobian matrix in the Gauss-Newton optimization algorithm. In this study, we have successfully integrated a lossy compression algorithm into our F3DT-SI workflow to significantly reduce the disk space for storing the strain tensor fields. The compressor supports a user-specified tolerance for bounding the error, and can be integrated into our finite-difference wave-propagation simulation code used for computing the strain fields. The decompressor can be integrated into the kernel calculation code that reads the strain fields from the disk and compute the data sensitivity kernels. During the wave-propagation simulations, we compress the strain fields before writing them to the disk. To compute the data sensitivity kernels, we read the compressed strain fields from the disk and decompress them before using them in kernel calculations. Experiments using a realistic dataset in our California statewide F3DT project have shown that we can reduce the strain-field disk storage by at least an order of magnitude with acceptable loss, and also improve the overall I/O performance of the entire F3DT-SI workflow significantly. The integration of the lossy online compressor may potentially open up the possibilities of the wide adoption of F3DT-SI in routine seismic tomography practices in the near future.

  11. Reducing Disk Storage of Full-3D Seismic Waveform Tomography (F3DT) Through Lossy Online Compression

    SciTech Connect

    Lindstrom, Peter; Chen, Po; Lee, En-Jui

    2016-05-05

    Full-3D seismic waveform tomography (F3DT) is the latest seismic tomography technique that can assimilate broadband, multi-component seismic waveform observations into high-resolution 3D subsurface seismic structure models. The main drawback in the current F3DT implementation, in particular the scattering-integral implementation (F3DT-SI), is the high disk storage cost and the associated I/O overhead of archiving the 4D space-time wavefields of the receiver- or source-side strain tensors. The strain tensor fields are needed for computing the data sensitivity kernels, which are used for constructing the Jacobian matrix in the Gauss-Newton optimization algorithm. In this study, we have successfully integrated a lossy compression algorithm into our F3DT SI workflow to significantly reduce the disk space for storing the strain tensor fields. The compressor supports a user-specified tolerance for bounding the error, and can be integrated into our finite-difference wave-propagation simulation code used for computing the strain fields. The decompressor can be integrated into the kernel calculation code that reads the strain fields from the disk and compute the data sensitivity kernels. During the wave-propagation simulations, we compress the strain fields before writing them to the disk. To compute the data sensitivity kernels, we read the compressed strain fields from the disk and decompress them before using them in kernel calculations. Experiments using a realistic dataset in our California statewide F3DT project have shown that we can reduce the strain-field disk storage by at least an order of magnitude with acceptable loss, and also improve the overall I/O performance of the entire F3DT-SI workflow significantly. The integration of the lossy online compressor may potentially open up the possibilities of the wide adoption of F3DT-SI in routine seismic tomography practices in the near future.

  12. The application of seismic stratigraphic methods on exploration 3D seismic data to define a reservoir model in OPL 210, Deepwater Nigeria

    SciTech Connect

    Ragnhild, L.; Ventris, P.; Osahon, G.

    1995-08-01

    OPL 210 lies in deepwater on the northwestern flank of the Niger Delta. The partners in this block are Allied Energy and The Statoil and BP Alliance. The license has a 5 year initial exploration phase and carries a 2 well commitment. At present the database comprises a 1 x 1 km grid of 2D seismic across the block, and 450 sq. km of 3D in an area of special interest. A larger 3D survey is planned for 1995. Little is known about the reservoir in the deep water, but we expect our main target to be ponded slope and basin turbidites. As such the bulk of the shelf well data available has little or no relevance to the play type likely to be encountered. Prior to drilling, seismic stratigraphy has been one of several methods used to generate a consistent predictive reservoir model. The excellent quality and high resolution of the 3D data have allowed identification and detailed description of several distinctive seismic facies. These facies are described in terms of their internal geometries and stacking patterns. The geometries are then interpreted based on a knowledge of depositional processes from analog slope settings. This enables a predictive model to be constructed for the distribution of reservoir within the observed facies. These predictions will be tested by one of the first wells drilled in the Nigerian deepwater in mid 1995.

  13. High-resolution 3D seismic imaging of a pull-apart basin in the Gulf of Cadiz

    NASA Astrophysics Data System (ADS)

    Crutchley, G.; Berndt, C.; Klaeschen, D.; Gutscher, M.

    2009-12-01

    In 2006, high-resolution 3D seismic data were acquired in the Gulf of Cadiz and the Mediterranean Sea aboard the RRS Charles Darwin as part of the HERMES (Hotspot Ecosystem Research on the Margins of European Seas) project. The P-Cable system, a cost-efficient set-up for fast acquisition of 3D seismic data on 12 single-channel streamers, was utilized to acquire seismic cubes at four different targets. Here, we present results from the second target - a WNW-ESE-oriented pull-apart basin in the southeastern Gulf of Cadiz. Initial processing has included: 1) spatial positioning of each recording channel from GPS data acquired on the outer two channels, 2) improved positioning of shot points and channels from the inversion of first arrival times, 3) application of a swell filter to improve reflection coherency, 4) CDP binning and stacking and 5) migration. The new data confirm that the southeastern Gulf of Cadiz north of the Rharb submarine valley is structurally controlled by numerous strike slip faults that were active until quite recently (within the resolution of the data). Given the location of this basin, between the extensional domain on the upper slope and the compressional toe of the accretionary wedge, we interpret the origin to be gravitational sliding on a detachment layer, possibly containing salt, but at this stage not imaged by our profiles.

  14. Modeling and validation of a 3D velocity structure for the Santa Clara Valley, California, for seismic-wave simulations

    USGS Publications Warehouse

    Hartzell, S.; Harmsen, S.; Williams, R.A.; Carver, D.; Frankel, A.; Choy, G.; Liu, P.-C.; Jachens, R.C.; Brocher, T.M.; Wentworth, C.M.

    2006-01-01

    A 3D seismic velocity and attenuation model is developed for Santa Clara Valley, California, and its surrounding uplands to predict ground motions from scenario earthquakes. The model is developed using a variety of geologic and geophysical data. Our starting point is a 3D geologic model developed primarily from geologic mapping and gravity and magnetic surveys. An initial velocity model is constructed by using seismic velocities from boreholes, reflection/refraction lines, and spatial autocorrelation microtremor surveys. This model is further refined and the seismic attenuation is estimated through waveform modeling of weak motions from small local events and strong-ground motion from the 1989 Loma Prieta earthquake. Waveforms are calculated to an upper frequency of 1 Hz using a parallelized finite-difference code that utilizes two regions with a factor of 3 difference in grid spacing to reduce memory requirements. Cenozoic basins trap and strongly amplify ground motions. This effect is particularly strong in the Evergreen Basin on the northeastern side of the Santa Clara Valley, where the steeply dipping Silver Creek fault forms the southwestern boundary of the basin. In comparison, the Cupertino Basin on the southwestern side of the valley has a more moderate response, which is attributed to a greater age and velocity of the Cenozoic fill. Surface waves play a major role in the ground motion of sedimentary basins, and they are seen to strongly develop along the western margins of the Santa Clara Valley for our simulation of the Loma Prieta earthquake.

  15. Joint Stochastic Inversion of Pre-Stack 3D Seismic Data and Well Logs for High Resolution Hydrocarbon Reservoir Characterization

    NASA Astrophysics Data System (ADS)

    Torres-Verdin, C.

    2007-05-01

    This paper describes the successful implementation of a new 3D AVA stochastic inversion algorithm to quantitatively integrate pre-stack seismic amplitude data and well logs. The stochastic inversion algorithm is used to characterize flow units of a deepwater reservoir located in the central Gulf of Mexico. Conventional fluid/lithology sensitivity analysis indicates that the shale/sand interface represented by the top of the hydrocarbon-bearing turbidite deposits generates typical Class III AVA responses. On the other hand, layer- dependent Biot-Gassmann analysis shows significant sensitivity of the P-wave velocity and density to fluid substitution. Accordingly, AVA stochastic inversion, which combines the advantages of AVA analysis with those of geostatistical inversion, provided quantitative information about the lateral continuity of the turbidite reservoirs based on the interpretation of inverted acoustic properties (P-velocity, S-velocity, density), and lithotype (sand- shale) distributions. The quantitative use of rock/fluid information through AVA seismic amplitude data, coupled with the implementation of co-simulation via lithotype-dependent multidimensional joint probability distributions of acoustic/petrophysical properties, yields accurate 3D models of petrophysical properties such as porosity and permeability. Finally, by fully integrating pre-stack seismic amplitude data and well logs, the vertical resolution of inverted products is higher than that of deterministic inversions methods.

  16. 3-D Velocity Model of the Coachella Valley, Southern California Based on Explosive Shots from the Salton Seismic Imaging Project

    NASA Astrophysics Data System (ADS)

    Persaud, P.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.; Scheirer, D. S.

    2014-12-01

    We have analyzed explosive shot data from the 2011 Salton Seismic Imaging Project (SSIP) across a 2-D seismic array and 5 profiles in the Coachella Valley to produce a 3-D P-wave velocity model that will be used in calculations of strong ground shaking. Accurate maps of seismicity and active faults rely both on detailed geological field mapping and a suitable velocity model to accurately locate earthquakes. Adjoint tomography of an older version of the SCEC 3-D velocity model shows that crustal heterogeneities strongly influence seismic wave propagation from moderate earthquakes (Tape et al., 2010). These authors improve the crustal model and subsequently simulate the details of ground motion at periods of 2 s and longer for hundreds of ray paths. Even with improvements such as the above, the current SCEC velocity model for the Salton Trough does not provide a match of the timing or waveforms of the horizontal S-wave motions, which Wei et al. (2013) interpret as caused by inaccuracies in the shallow velocity structure. They effectively demonstrate that the inclusion of shallow basin structure improves the fit in both travel times and waveforms. Our velocity model benefits from the inclusion of known location and times of a subset of 126 shots detonated over a 3-week period during the SSIP. This results in an improved velocity model particularly in the shallow crust. In addition, one of the main challenges in developing 3-D velocity models is an uneven stations-source distribution. To better overcome this challenge, we also include the first arrival times of the SSIP shots at the more widely spaced Southern California Seismic Network (SCSN) in our inversion, since the layout of the SSIP is complementary to the SCSN. References: Tape, C., et al., 2010, Seismic tomography of the Southern California crust based on spectral-element and adjoint methods: Geophysical Journal International, v. 180, no. 1, p. 433-462. Wei, S., et al., 2013, Complementary slip distributions

  17. Potential Geophysical Field Transformations and Combined 3D Modelling for Estimation the Seismic Site Effects on Example of Israel

    NASA Astrophysics Data System (ADS)

    Eppelbaum, Lev; Meirova, Tatiana

    2015-04-01

    It is well-known that the local seismic site effects may have a significant contribution to the intensity of damage and destruction (e.g., Hough et al., 1990; Regnier et al., 2000; Bonnefoy-Claudet et al., 2006; Haase et al., 2010). The thicknesses of sediments, which play a large role in amplification, usually are derived from seismic velocities. At the same time, thickness of sediments may be determined (or defined) on the basis of 3D combined gravity-magnetic modeling joined with available geological materials, seismic data and borehole section examination. Final result of such investigation is a 3D physical-geological model (PGM) reflecting main geological peculiarities of the area under study. Such a combined study needs in application of a reliable 3D mathematical algorithm of computation together with advanced methodology of 3D modeling. For this analysis the developed GSFC software was selected. The GSFC (Geological Space Field Calculation) program was developed for solving a direct 3-D gravity and magnetic prospecting problem under complex geological conditions (Khesin et al., 1996; Eppelbaum and Khesin, 2004). This program has been designed for computing the field of Δg (Bouguer, free-air or observed value anomalies), ΔZ, ΔX, ΔY , ΔT , as well as second derivatives of the gravitational potential under conditions of rugged relief and inclined magnetization. The geological space can be approximated by (1) three-dimensional, (2) semi-infinite bodies and (3) those infinite along the strike closed, L.H. non-closed, R.H. on-closed and open). Geological bodies are approximated by horizontal polygonal prisms. The program has the following main advantages (besides abovementioned ones): (1) Simultaneous computing of gravity and magnetic fields; (2) Description of the terrain relief by irregularly placed characteristic points; (3) Computation of the effect of the earth-air boundary by the method of selection directly in the process of interpretation; (4

  18. Seismicity patterns along the Ecuadorian subduction zone: new constraints from earthquake location in a 3-D a priori velocity model

    NASA Astrophysics Data System (ADS)

    Font, Yvonne; Segovia, Monica; Vaca, Sandro; Theunissen, Thomas

    2013-04-01

    To improve earthquake location, we create a 3-D a priori P-wave velocity model (3-DVM) that approximates the large velocity variations of the Ecuadorian subduction system. The 3-DVM is constructed from the integration of geophysical and geological data that depend on the structural geometry and velocity properties of the crust and the upper mantle. In addition, specific station selection is carried out to compensate for the high station density on the Andean Chain. 3-D synthetic experiments are then designed to evaluate the network capacity to recover the event position using only P arrivals and the MAXI technique. Three synthetic earthquake location experiments are proposed: (1) noise-free and (2) noisy arrivals used in the 3-DVM, and (3) noise-free arrivals used in a 1-DVM. Synthetic results indicate that, under the best conditions (exact arrival data set and 3-DVM), the spatiotemporal configuration of the Ecuadorian network can accurately locate 70 per cent of events in the frontal part of the subduction zone (average azimuthal gap is 289° ± 44°). Noisy P arrivals (up to ± 0.3 s) can accurately located 50 per cent of earthquakes. Processing earthquake location within a 1-DVM almost never allows accurate hypocentre position for offshore earthquakes (15 per cent), which highlights the role of using a 3-DVM in subduction zone. For the application to real data, the seismicity distribution from the 3-D-MAXI catalogue is also compared to the determinations obtained in a 1-D-layered VM. In addition to good-quality location uncertainties, the clustering and the depth distribution confirm the 3-D-MAXI catalogue reliability. The pattern of the seismicity distribution (a 13 yr record during the inter-seismic period of the seismic cycle) is compared to the pattern of rupture zone and asperity of the Mw = 7.9 1942 and the Mw = 7.7 1958 events (the Mw = 8.8 1906 asperity patch is not defined). We observe that the nucleation of 1942, 1958 and 1906 events coincides with

  19. The use of exploration 3D seismic data to optimise oil exploration in OPL 210 deepwater, Nigeria

    SciTech Connect

    Nelson, L.C.; Lilletveit, R.; Sandvoll, T.

    1995-08-01

    Allied Energy and the Statoil and BP Alliance are currently partners in the OPL 210 license, in deepwater Nigeria. The license has a 5 year initial exploration phase which carries a two well commitment. To optimize the location of these wells in this challenging and costly drilling environment the partnership has decided to acquire extensive exploration 3D seismic data within the block. Interpretation of the first of two planned 3D surveys has led to a much clearer understanding of: (a) The structural segmentation of the prospect and thus a clearer idea of the likely hydrocarbon pool size. (b) The distribution of amplitude anomalies and thus, hopefully, a superior understanding of reservoir distribution and hydrocarbons. Here the limiting factor is clearly the lack of deepwater geophysical calibration, due to the absence of wells. Consequently, conclusions at this stage, are qualitative either than quantative. Combined with detailed seismic stratigraphic and high tech geophysical analysis, these two aspects will assist in the highgrading of segments in the prospect, prior to final decisions on the well locations. The first well, planned for 1995, will be one of the first wells drilled in the Nigerian deepwater area. Examples of both 2D and 3D data will be used to demonstrate the above and some of the first well results will be integrated into our interpretation to highlight how some of our perceptions may have changed.

  20. Converted-Wave Processing of a 3D-3C Refection Seismic Survey of Soda Lake Geothermal Field

    NASA Astrophysics Data System (ADS)

    Louie, J. N.; Kent, T.; Echols, J.

    2012-12-01

    This 3D-3C seismic survey greatly improves the structural model of the Soda Lake, Nevada geothermal system. The picked top of a mudstone interval above reservoir levels reveals a detailed fault map. The geothermal reservoir is within a complex of nested grabens. Determining a "geothermal indicator" for the deeper reservoir in the seismic signal, and processing of the 3D converted-wave data, have been unsuccessful to date. Due to a high near-surface Vp/Vs ratio the shear-wave energy is under-sampled with 220 ft receiver spacing and 550 ft (168 m) line spacing. The 2D converted-wave data that we can image shows encouraging similarity to the deep structural features in the P-wave sections, but have little resolution of shallow structures. Higher-density receivers and a better shallow shear-wave model are needed in conjunction with this deep reflection study to effectively image the 3D converted waves.

  1. Use of 3D Seismic Azimuthal Iso-Frequency Volumes for the Detection and Characterization of High Porosity/Permeability Zones in Carbonate Reservoirs

    NASA Astrophysics Data System (ADS)

    Toelle, Brian E.

    Among the most important properties controlling the production from conventional oil and gas reservoirs is the distribution of porosity and permeability within the producing geologic formation. The geometry of the pore space within these reservoirs, and the permeability associated with this pore space geometry, impacts not only where production can occur and at what flow rates but can also have significant influence on many other rock properties. Zones of high matrix porosity can result in an isotropic response for certain reservoir properties whereas aligned porosity/permeability, such as open, natural fracture trends, have been shown to result in reservoirs being anisotropic in many properties. The ability to identify zones within a subsurface reservoir where porosity/permeability is significantly higher and to characterize them according to their geometries would be of great significance when planning where new boreholes, particularly horizontal boreholes, should be drilled. The detection and characterization of these high porosity/permeability zones using their isotropic and anisotropic responses may be possible through the analysis of azimuthal (also referred to as azimuth-limited) 3D seismic volumes. During this study the porosity/permeability systems of a carbonate, pinnacle reef within the northern Michigan Basin undergoing enhanced oil recovery were investigated using selected seismic attributes extracted from azimuthal 3D seismic volumes. Based on the response of these seismic attributes an interpretation of the geometry of the porosity/permeability system within the reef was made. This interpretation was supported by well data that had been obtained during the primary production phase of the field. Additionally, 4D seismic data, obtained as part of the CO2 based EOR project, supported reservoir simulation results that were based on the porosity/permeability interpretation.

  2. Using 3D Simulation of Elastic Wave Propagation in Laplace Domain for Electromagnetic-Seismic Inverse Modeling

    NASA Astrophysics Data System (ADS)

    Petrov, P.; Newman, G. A.

    2010-12-01

    -Fourier domain we had developed 3D code for full-wave field simulation in the elastic media which take into account nonlinearity introduced by free-surface effects. Our approach is based on the velocity-stress formulation. In the contrast to conventional formulation we defined the material properties such as density and Lame constants not at nodal points but within cells. This second order finite differences method formulated in the cell-based grid, generate numerical solutions compatible with analytical ones within the range errors determinate by dispersion analysis. Our simulator will be embedded in an inversion scheme for joint seismic- electromagnetic imaging. It also offers possibilities for preconditioning the seismic wave propagation problems in the frequency domain. References. Shin, C. & Cha, Y. (2009), Waveform inversion in the Laplace-Fourier domain, Geophys. J. Int. 177(3), 1067- 1079. Shin, C. & Cha, Y. H. (2008), Waveform inversion in the Laplace domain, Geophys. J. Int. 173(3), 922-931. Commer, M. & Newman, G. (2008), New advances in three-dimensional controlled-source electromagnetic inversion, Geophys. J. Int. 172(2), 513-535. Newman, G. A., Commer, M. & Carazzone, J. J. (2010), Imaging CSEM data in the presence of electrical anisotropy, Geophysics, in press.

  3. Quantitative time-lapse 3D seismic data interpretation from the pilot site of Ketzin (CO2 Storage): the level of noise

    NASA Astrophysics Data System (ADS)

    Ivanova, Alexandra; Lüth, Stefan; Kempka, Thomas

    2015-04-01

    The first European onshore pilot scale project for geological storage of carbon dioxide (CO2) was initiated in 2004 near Berlin (Germany). This project is multidisciplinary including 3D seismic time-lapse surveys as an essential tool for reservoir characterization at a depth of 650 m. A 3D pre-injection baseline seismic survey was acquired in 2005. CO2 injection into a sandstone saline aquifer started in 2008 and stopped in 2013 after 67 kilotons of CO2 had been injected. The 1st and 2nd 3D seismic repeat surveys were acquired after 22 and 61 kilotons of CO2 had been injected respectively. Time-lapse seismic processing, petrophysical data and geophysical logging of CO2 saturation levels have allowed for an estimate of the total amount of CO2 visible in the seismic data to be made. The close agreement (over 85%) between the injected and observed amount is encouraging for quantitative monitoring of a CO2 storage site using seismic methods. However this estimate contains a number of uncertainties. For example the most of the time delay values in the both 3D seismic repeat surveys within the amplitude anomaly are near the noise level of 1-2 ms, however a change of 1 ms in the time delay affects significantly the mass estimate, thus the choice of the time-delay cutoff is crucial. In this study we put bounds into the noise in seismic data from Ketzin using results of 3D flow simulations.

  4. 3D seismic geomorphology and geologic controls on gas hydrate accumulation mechanism in the Miyazaki-oki forearc basin, Japan

    NASA Astrophysics Data System (ADS)

    Komatsu, Y.; Kobayashi, T.; Fujii, T.

    2015-12-01

    The stratigraphy of the Miyazaki-oki forearc basin along the Southwest Japan Arc comprises the early Miocene to early Pleistocene Miyazaki Group and the Hyuganada Group. These groups comprise sediments (up to 5000 m) deposited in deep marine to shallow marine environments. Based on characteristics of well data outside seismic exploration area and stratigraphy of land areas, the Miyazaki Group was divided into four seismic units and the Hyuganada Group was divided into two seismic units. In this area, bottom-simulating reflectors (BSRs) have been widely observed and considered as representing lower boundaries of methane-hydrate-bearing deposits. However, the gas hydrate accumulation mechanism for this area is not yet well understood. We show the relation between sandy sediment distribution identified from the 3D seismic geomorphological analysis and methane hydrate occurrence to identify the accumulation mechanism. A submarine fan system was subdivided into four seismic facies: Submarine canyon complexes; Leveed channel complexes; Submarine fan complexes; Mass transport complexes (MTD). Depositional systems of target layers are characterized by a transition from submarine fan deposits (Miyazaki Group) to channel-levee deposits and MTD (Hyuganada Group). This transition of depositional environments is strongly influenced by global tectonics since early Miocene in the Southwest Japan Arc. A part of channel-fill located around structural wing and middle fan deposits above the BSR is inferred as sediments intercalated with sandy layers. We consider that these deposits contain methane hydrate because the sandy sediment distribution approximately coincides with a high-velocity zone as an indicator of gas hydrate. The comparison of the areal extent of the seismic facies and the mapped structural configuration, suggest that the gas hydrate accumulation represent combination structural-stratigraphic trap.

  5. A Robust MEMS Based Multi-Component Sensor for 3D Borehole Seismic Arrays

    SciTech Connect

    Paulsson Geophysical Services

    2008-03-31

    The objective of this project was to develop, prototype and test a robust multi-component sensor that combines both Fiber Optic and MEMS technology for use in a borehole seismic array. The use such FOMEMS based sensors allows a dramatic increase in the number of sensors that can be deployed simultaneously in a borehole seismic array. Therefore, denser sampling of the seismic wave field can be afforded, which in turn allows us to efficiently and adequately sample P-wave as well as S-wave for high-resolution imaging purposes. Design, packaging and integration of the multi-component sensors and deployment system will target maximum operating temperature of 350-400 F and a maximum pressure of 15000-25000 psi, thus allowing operation under conditions encountered in deep gas reservoirs. This project aimed at using existing pieces of deployment technology as well as MEMS and fiber-optic technology. A sensor design and analysis study has been carried out and a laboratory prototype of an interrogator for a robust borehole seismic array system has been assembled and validated.

  6. 3D density model of the upper mantle of Asia based on inversion of gravity and seismic tomography data

    NASA Astrophysics Data System (ADS)

    Kaban, Mikhail K.; Stolk, Ward; Tesauro, Magdala; El Khrepy, Sami; Al-Arifi, Nassir; Beekman, Fred; Cloetingh, Sierd A. P. L.

    2016-11-01

    We construct a new-generation 3D density model of the upper mantle of Asia and its surrounding areas based on a joint interpretation of several data sets. A recent model of the crust combining nearly all available seismic data is employed to calculate the impact of the crust on the gravity anomalies and observed topography and to estimate the residual mantle anomalies and residual topography. These fields are jointly inverted to calculate the density variations in the lithosphere and upper mantle down to 325 km. As an initial approximation, we estimate density variations using a seismic tomography model. Seismic velocity variations are converted into temperatures and then to density variations based on mineral physics constraints. In the Occam-type inversion, we fit both the residual mantle gravity anomalies and residual topography by finding deviations to the initial model. The obtained corrections improve the resolution of the initial model and reflect important features of the mantle structure that are not well resolved by the seismic tomography. The most significant negative corrections of the upper mantle density, found in the Siberian and East European cratons, can be associated with depleted mantle material. The most pronounced positive density anomalies are found beneath the Tarim and South Caspian basins, Barents Sea, and Bay of Bengal. We attribute these anomalies to eclogites in the uppermost mantle, which have substantially affected the evolution of the basins. Furthermore, the obtained results provide evidence for the presence of eclogites in the oceanic subducting mantle lithosphere.

  7. 3D Seismic Imaging of a Geological Storage of CO2 Site: Hontomín (Spain)

    NASA Astrophysics Data System (ADS)

    Alcalde, Juan; Martí, David; Juhlin, Christopher; Malehmir, Alireza; Sopher, Daniel; Marzán, Ignacio; Calahorrano, Alcinoe; Ayarza, Puy; Pérez-Estaún, Andrés; Carbonell, Ramon

    2013-04-01

    A 3D seismic reflection survey was acquired in the summer of 2010 over the Hontomín CO2 storage site (Spain), with the aim of imaging its internal structure and to provide a 3D seismic baseline model prior to CO2 injection. The 36 km2 survey utilised 25 m source and receiver point spacing and 5000 shotpoints recorded with mixed source (Vibroseis and explosives). The target reservoir is a saline aquifer located at approximately 1450 m, within Lower Jurassic carbonates (Lias). The main seal is formed by inter-layered marls and marly limestones of Early to Middle Jurassic age (Dogger and Lias). The relatively complex geology and the rough topography strongly influenced the selection of parameters for the data processing. Static corrections and post stack migration were shown to be the most important processes affecting the quality of the final image. The match between the differing source wavelets is also studied here. The resulting 3D image provides information of all the relevant geological features of the storage site, including position and shape of the main underground formations. The target structure is an asymmetric dome. The steepest flank of the structure was selected as the optimum location for CO2 injection, where the updip migration of the plume is anticipated. A major strike slip fault (the South fault), crossing the study area W-E, has been mapped through the whole seismic volume. The injection position and the expected migration plume are located to the north of this main fault and away from its influence.

  8. 3D crustal velocity structure beneath the broadband seismic array in the Gyeongju area of Korea by receiver function analyses

    NASA Astrophysics Data System (ADS)

    Lee, Dong Hun; Lee, Jung Mo; Cho, Hyun-Moo; Kang, Tae-Seob

    2016-10-01

    A temporary seismic array was in operation between October 2010 and March 2013 in the Gyeongju area of Korea. Teleseismic records of the seismic array appropriate for receiver function analysis were collected, and selected seismograms were split into five groups based on epicenters-the Banda-Molucca, Sumatra, Iran, Aleutian, and Vanuatu groups. 1D velocity structures beneath each seismic station were estimated by inverting the stacked receiver functions for possible groups. The inversion was done by applying a genetic algorithm, whereas surface wave dispersion data were used as constraints to avoid non-uniqueness in the inversion. The composite velocity structure was constructed by averaging the velocity structures weighted by the number of receiver functions used in stacking. The uncertainty analysis for the velocity structures showed that the average of 95% confidence intervals was ± 0.1 km/s. The 3D velocity structure was modeled through interpolation of 1D composite velocity structures. Moho depths were determined in each composite velocity structure based on the AK135-F S-wave velocity model, and the depths were similar to the H-κ analysis results. The deepest Moho depth in the study area was found to be 31.9 km, and the shallowest, was 25.9 km. The Moho discontinuity dips in a southwestward direction beneath the area. A low velocity layer was also detected between 4 and 14 km depth. Adakitic intrusions and/or a high geothermal gradient appear to be the causes of this low velocity layer. The 3D velocity structure can be used to reliably assess seismic hazards in this area.

  9. Marine forearc extension in the Hikurangi Margin: New insights from high-resolution 3D seismic data

    NASA Astrophysics Data System (ADS)

    Böttner, Christoph; Gross, Felix; Geersen, Jacob; Mountjoy, Joshu; Crutchley, Gareth; Krastel, Sebastian

    2017-04-01

    In subduction zones upper-plate normal faults have long been considered a tectonic feature primarily associated with erosive margins. However, increasing data coverage has proven that similar features also occur in accretionary margins, such as Cascadia, Makran, Nankai or Central Chile, where kinematics are dominated by compression. Considering their wide distribution there is, without doubt, a significant lack of qualitative and quantitative knowledge regarding the role and importance of normal faults and zones of extension for the seismotectonic evolution of accretionary margins. We use a high-resolution 3D P-Cable seismic volume from the Hikurangi Margin acquired in 2014 to analyze the spatial distribution and mechanisms of upper-plate normal faulting. The study area is located at the upper continental slope in the area of the Tuaheni landslide complex. In detail we aim to (1) map the spatial distribution of normal faults and characterize their vertical throws, strike directions, and dip angles; (2) investigate their possible influence on fluid migration in an area, where gas hydrates are present; (3) discuss the mechanisms that may cause extension of the upper-slope in the study area. Beneath the Tuaheni Landslide Complex we mapped about 200 normal faults. All faults have low displacements (<15 m) and dip at high (> 65°) angles. About 71% of the faults dip landward. We found two main strike directions, with the majority of faults striking 350-10°, parallel to the deformation front. A second group of faults strikes 40-60°. The faults crosscut the BSR, which indicates the base of the gas hydrate zone. In combination with seismically imaged bright-spots and pull-up structures, this indicates that the normal faults effectively transport fluids vertically across the base of the gas hydrate zone. Localized uplift, as indicated by the presence of the Tuaheni Ridge, might support normal faulting in the study area. In addition, different subduction rates across the

  10. 9C-3D seismic interpretation of the Bakken Formation, Banner Field, North Dakota

    NASA Astrophysics Data System (ADS)

    Comegys, Lillian R.

    The Bakken Petroleum System is a multi-reservoir play with estimated total undiscovered resources of 3.649 BBO oil and 1.85 TCF natural gas in the United States portion of the Williston Basin (Pollastro 2008). The presence of natural fractures in all three members of the Bakken Formation have been linked to high initial production (IP) and cumulative production from the Antelope Field and better reservoir potential in the Elm Coulee Field and Sanish Fields (Sturm and Gomez 2009; Honsberger 2012; Theloy 2011). Therefore, the ability of seismic data to determine the presence, orientation, and density of natural fractures is an important achievement for petroleum exploration and exploitation. The STAMPEDE 9-component seismic survey is located in Mountrail County, North Dakota, in the Banner Field, southeast of the Parshall and Sanish Fields. It is the goal of the Reservoir Characterization Project to analyze the structural influences on reservoir properties in the STAMPEDE survey area using the compressional and pure shear seismic volumes supplemented by the public well information available on the North Dakota Industrial Commission website. Fracturing induced by basement faulting and lithology changes is detectable using multicomponent seismic data in the Stampede seismic survey. Shear wave splitting analysis delineates zones of different fracture orientation and density. These areas correlate to interpreted fault intersections and the predicted area of increased fracture frequency based on facies changes in the Middle Bakken Member and its mechanical stratigraphy. Wrench fault mechanics are at work in the study area, creating isolated convergent and divergent stress regimes in the separate fault blocks. Main fault interpretations are based on shear wave isochron mapping, wireline log mapping, seismic panel observations. Fracture interpretations were made on the analysis of shear time and amplitude anisotropy maps and the correlation of a P-wave Velocity Variation

  11. Effect of rapid grounding line migration investigated with 3D ice sheet-ice shelf models (MISMIP3d)

    NASA Astrophysics Data System (ADS)

    Pattyn, F.; Docquier, D.; Durand, G.; Favier, L.; Gagliardini, O.; Hindmarsh, R.; Zwinger, T.; Mismip3d Participants

    2012-04-01

    Understanding and attributing future sea-level changes demands serious efforts on the development of efficient ice sheet-ice shelf models that capture the essential physics and mechanics of grounding line behavior. While semi-analytical solutions for grounding line behavior are available for the flowline case, such solution fails to exist for more complex three-dimensional geometries. A way of evaluating the quality of ice sheet models is to verify them against more complex model solutions under controlled conditions (Marine Ice Sheet Model Intercomparison - MISMIP). Given the computational demands of such models, it is extremely attractive from a computational point of view to use flux/thickness parameterizations in 3d models. Here we investigated the transition between ice sheet and ice shelf with series of different numerical models, ranging from full Stokes (Elmer/Ice) models, pseudo-spectral methods to a 2d vertically integrated finite-difference 'shelfy-stream' model, taking into account grounding line dynamics, and using parameterizations by Schoof (2007) and Pollard and DeConto (2009). Rapid grounding line migration was provoked by changing sliding at the grounding line, resulting in curved grounding lines influenced by lateral effects. We tested whether flux parameterizations are still valid under such conditions, especially when buttressing effects are taken into account. Results of other participants in the intercomparison exercise are presented alongside the initial benchmark results.

  12. From 2D to 3D: novel nanostructured scaffolds to investigate signalling in reconstructed neuronal networks

    PubMed Central

    Bosi, Susanna; Rauti, Rossana; Laishram, Jummi; Turco, Antonio; Lonardoni, Davide; Nieus, Thierry; Prato, Maurizio; Scaini, Denis; Ballerini, Laura

    2015-01-01

    To recreate in vitro 3D neuronal circuits will ultimately increase the relevance of results from cultured to whole-brain networks and will promote enabling technologies for neuro-engineering applications. Here we fabricate novel elastomeric scaffolds able to instruct 3D growth of living primary neurons. Such systems allow investigating the emerging activity, in terms of calcium signals, of small clusters of neurons as a function of the interplay between the 2D or 3D architectures and network dynamics. We report the ability of 3D geometry to improve functional organization and synchronization in small neuronal assemblies. We propose a mathematical modelling of network dynamics that supports such a result. Entrapping carbon nanotubes in the scaffolds remarkably boosted synaptic activity, thus allowing for the first time to exploit nanomaterial/cell interfacing in 3D growth support. Our 3D system represents a simple and reliable construct, able to improve the complexity of current tissue culture models. PMID:25910072

  13. Reservoir estimation in the Penobscot 3D seismic volume using Constrained Sparse Spike Inversion, offshore Nova Scotia, Canada

    NASA Astrophysics Data System (ADS)

    Xiao, Mengchu

    The Penobscot study area is located offshore Nova Scotia, Canada. There are two wells, which penetrate the highest potentially commercial bodies in the Abenaki Formation. In order to investigate the potential for locating additional hydrocarbon reservoirs, well log data was used and the Penobscot 3D seismic dataset was analyzed using Constrained Sparse Spike Inversion. From the well log data, low GR and SP values are an indication of a permeable sand layer, which provides the target zone in this study. Impedance - porosity crossplots gave the relationship between impedance and porosity, where a low impedance sand layer is correlated with high porosity. It was found that the target sand layer has low impedance, a feature recognizable from the inversion results. The porosity of the whole sand layer calculated by the linear function from the relationship between impedance and porosity. The calculation of thickness of this sand layer from maps representing different impedance intervals provided numeric evidence to show there is a low impedance sand layer in the well L-30. The pore thickness map results indicate there is greater pore thickness in well L-30 than B-41. It appears that the company drilled at the optimal location for the initial (L-30) well, and tested the extent of potential reservoir rock with the second (B-41) well. The potential reservoir is apparently fairly small, and restricted to the area around L-30. There may or may not be value in testing another location across a fault, but the rock behind the fault is likely not as high quality as at L-30 and the high-quality regions are small in size and not connected.

  14. 3-D Seismic Methods for Geothermal Reservoir Exploration and Assessment--Summary

    SciTech Connect

    Majer, E.L.

    2003-07-14

    A wide variety of seismic methods covering the spectrum from DC to kilohertz have been employed at one time or the other in geothermal environments. The reasons have varied from exploration for a heat source to attempting to find individual fractures producing hot fluids. For the purposes here we will assume that overall objective of seismic imaging is for siting wells for successful location of permeable pathways (often fracture permeability) that are controlling flow and transport in naturally fractured reservoirs. The application could be for exploration of new resources or for in-fill/step-out drilling in existing fields. In most geothermal environments the challenge has been to separate the ''background'' natural complexity and heterogeneity of the matrix from the fracture/fault heterogeneity controlling the fluid flow. Ideally one not only wants to find the fractures, but the fractures that are controlling the flow of the fluids. Evaluated in this work is current state-of-the-art surface (seismic reflection) and borehole seismic methods (Vertical Seismic Profiling (VSP), Crosswell and Single Well) to locate and quantify geothermal reservoir characteristics. The focus is on active methods; the assumption being that accuracy is needed for successful well siting. Passive methods are useful for exploration and detailed monitoring for in-fill drilling, but in general the passive methods lack the precision and accuracy for well siting in new or step out areas. In addition, MEQ activity is usually associated with production, after the field has been taken to a mature state, thus in most cases it is assumed that there is not enough MEQ activity in unproduced areas to accurately find the permeable pathways. The premise of this review is that there may new developments in theory and modeling, as well as in data acquisition and processing, which could make it possible to image the subsurface in much more detail than 15 years ago. New understanding of the effect of

  15. Extending field life in offshore Gulf of Mexico using 3-D seismic survey

    SciTech Connect

    Bulling, T.P.; Olsen, R.S. )

    1990-05-01

    Discovered by ARCO in 1967, the High Island 24L field (lower Miocene) is located in the Texas state waters of the Gulf of Mexico. By 1986, the field had produced 320 billion ft{sup 3} of gas and 3.0 million bbl of oil. An engineering field study completed in 1986 showed the field was declining and would be unprofitable within 3 yr. Study of reservoir maps revealed three basin problems: volumetric reserve calculations were less than reserves produced, hydrocarbon-water contacts were inconsistent between wells thought to be in communication, and ultimate recoveries could not be accurately calculated. Attempts to remap the field with the existing two-dimensional seismic data base and well data proved unsuccessful. In 1986, a three-dimensional seismic survey was acquired in an effort to evaluate the true present worth and potential of the field. Remapping of 30 reservoir horizons began in 1987. The integration of detailed well log correlations tied to the dense grid of quality three dimensional seismic data improved the reservoir maps. These maps helped resolve engineering problems by defining the configuration of the reservoirs more accurately. Reservoir maps now closely match volumetrics, fluid contacts within reservoir units are consistent, and a better definition of extension well opportunities exists. The authors study resulted in six additional wells. These wells along with engineering modifications and operations cost containment resulted in the extension of the economic life of the High Island 24-L field by at least 8 yr.

  16. High-resolution 3D seismic reflection imaging across active faults and its impact on seismic hazard estimation in the Tokyo metropolitan area

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Sato, Hiroshi; Abe, Susumu; Kawasaki, Shinji; Kato, Naoko

    2016-10-01

    We collected and interpreted high-resolution 3D seismic reflection data across a hypothesized fault scarp, along the largest active fault that could generate hazardous earthquakes in the Tokyo metropolitan area. The processed and interpreted 3D seismic cube, linked with nearby borehole stratigraphy, suggests that a monocline that deforms lower Pleistocene units is unconformably overlain by middle Pleistocene conglomerates. Judging from structural patterns and vertical separation on the lower-middle Pleistocene units and the ground surface, the hypothesized scarp was interpreted as a terrace riser rather than as a manifestation of late Pleistocene structural growth resulting from repeated fault activity. Devastating earthquake scenarios had been predicted along the fault in question based on its proximity to the metropolitan area, however our new results lead to a significant decrease in estimated fault length and consequently in the estimated magnitude of future earthquakes associated with reactivation. This suggests a greatly reduced seismic hazard in the Tokyo metropolitan area from earthquakes generated by active intraplate crustal faults.

  17. 3D Simulation of Elastic Wave Propagation in Heterogeneous Anisotropic Media in Laplace Domain for Electromagnetic-Seismic Inverse Modeling

    NASA Astrophysics Data System (ADS)

    Petrov, P.; Newman, G. A.

    2011-12-01

    Recent developments in high resolution imaging technology of subsurface objects involves a combination of different geophysical measurements (gravity, EM and seismic). A joint image of the subsurface geophysical attributes (velocity, electrical conductivity and density) requires the consistent treatment of the different geophysical data due to their differing physical nature. For example, in conducting media, which is typical of the Earth's interior, EM energy propagation is defined by a diffusive mechanism and may be characterized by two specific length scales: wavelength and skin depth. However, the propagation of seismic signals is a multiwave process and is characterized by a set of wavelengths. Thus, to consistently treat seismic and electromagnetic data an additional length scale is needed for seismic data that does not directly depend on a wavelength and describes a diffusive process, similar to EM wave propagation in the subsurface. Works by Brown et al.(2005), Shin and Cha(2008), and Shin and Ha(2008) suggest that an artificial damping of seismic wave fields via Laplace-Fourier transformation can be an effective approach to obtain a seismic data that have similar spatial resolution to EM data. The key benefit of such transformation is that diffusive wave-field inversion works well for both data sets: seismic (Brown et al.,2005; Shin and Cha,2008) and electromagnetic (Commer and Newman,2008; Newman et al.,2010). With the recent interest in the Laplace-Fourier domain full waveform inversion, 3D fourth and second-order finite-difference schemes for modeling of seismic wave propagation have been developed (Petrov and Newman, 2010). Incorporation of attenuation and anisotropy into a velocity model is a necessary step for a more realistic description of subsurface media. Here we consider the extension of our method which includes attenuation and VTI anisotropy. Our approach is based on the integro-interpolation technique for velocity-stress formulation. Seven

  18. Cataloguing Seismic Waveform Properties Recorded With a 3D Network in a Gold Mine in South Africa

    NASA Astrophysics Data System (ADS)

    Julia, J.; Nyblade, A. A.; Gok, R.; Walter, W. R.; Linzer, L.; Durrheim, R. J.; Dirks, P.

    2007-12-01

    The SAVUKA gold mine is located in the northwestern edge of the Witwatersrand basin, a Late Archean (3.07- 2.71~Ga) intracratonic basin in South Africa that hosts the largest known gold-uranium-pyrite ore deposits in the world. Seismic events related to the mine activity span several orders of magnitude through a variety of sources that include mine blasts, pillar collapses, and faulting events. These events are systematically recorded and catalogued through an in-mine, 3D seismic network consisting of 20, three-component, short-period stations with natural frequencies ranging between 4.5 and 28.0~Hz and deployed as deep as ~3.5 km. After 5 months of seismic monitoring of the mine, we have been able to assemble a database of over 6000 events spanning magnitudes in the -2.5 < ML < 4.4 range. The potential of this unique data set for characterizing the detailed seismic properties of the basin and studying source properties of non-double couple events is explored through simple, first-pass analysis on the recorded waveforms. Moreover, the in-mine network is complemented by a small array of 4 broadband stations interspaced ~10~km apart on the surface of the mine, and by a number of AfricaArray stations in South Africa and neighboring countries located at regional distances (50- 1000~km) from the mine. The largest mine-induced events are clearly recorded at distances as far away from the mine as 450~km and provide a unique opportunity for studying the regional propagation of seismic phases as well as the structure of the cratonic crust underlying the basin.

  19. Efficient realization of 3D joint inversion of seismic and magnetotelluric data with cross gradient structure constraint

    NASA Astrophysics Data System (ADS)

    Luo, H.; Zhang, H.; Gao, J.

    2016-12-01

    Seismic and magnetotelluric (MT) imaging methods are generally used to characterize subsurface structures at various scales. The two methods are complementary to each other and the integration of them is helpful for more reliably determining the resistivity and velocity models of the target region. Because of the difficulty in finding empirical relationship between resistivity and velocity parameters, Gallardo and Meju [2003] proposed a joint inversion method enforcing resistivity and velocity models consistent in structure, which is realized by minimizing cross gradients between two models. However, it is extremely challenging to combine two different inversion systems together along with the cross gradient constraints. For this reason, Gallardo [2007] proposed a joint inversion scheme that decouples the seismic and MT inversion systems by iteratively performing seismic and MT inversions as well as cross gradient minimization separately. This scheme avoids the complexity of combining two different systems together but it suffers the issue of balancing between data fitting and structure constraint. In this study, we have developed a new joint inversion scheme that avoids the problem encountered by the scheme of Gallardo [2007]. In the new scheme, seismic and MT inversions are still separately performed but the cross gradient minimization is also constrained by model perturbations from separate inversions. In this way, the new scheme still avoids the complexity of combining two different systems together and at the same time the balance between data fitting and structure consistency constraint can be enforced. We have tested our joint inversion algorithm for both 2D and 3D cases. Synthetic tests show that joint inversion better reconstructed the velocity and resistivity models than separate inversions. Compared to separate inversions, joint inversion can remove artifacts in the resistivity model and can improve the resolution for deeper resistivity structures. We

  20. Successful gas hydrate prospecting using 3D seismic - A case study for the Mt. Elbert prospect, Milne Point, North Slope Alaska

    USGS Publications Warehouse

    Inks, T.L.; Agena, W.F.

    2008-01-01

    In February 2007, the Mt. Elbert Prospect stratigraphic test well, Milne Point, North Slope Alaska encountered thick methane gas hydrate intervals, as predicted by 3D seismic interpretation and modeling. Methane gas hydrate-saturated sediment was found in two intervals, totaling more than 100 ft., identified and mapped based on seismic character and wavelet modeling.

  1. Combining 3D seismic tomography and ground-penetrating radar to reveal the structure of a megalithic burial tomb

    NASA Astrophysics Data System (ADS)

    Mendes, Manuela; Caldeira, Bento; Borges, José

    2017-04-01

    This work describes a case study concerning a prehistoric buried tomb (around 3000 years B.C.) located near Évora (Portugal). This monument is a tomb completely buried with only five visible irregular small stones distributed in a circle of 3 meter in diameter. A multi-approach combining 3D seismic tomography and ground-penetrating radar (GPR) have been applied to identify hidden elements and arrangement of the stones, required prior to any excavation work. The methodology for the 3D seismic data acquisition involves a total of 24 shots recorded by four lines, with twelve fixed receivers each one. For the GPR survey was used a 400 MHz antenna which moves along parallel lines with 50 cm separation, over a 30x30 m2 area that contains the buried tomb; the GPR unit was configured to a horizontal rate of 50 scans per meter (1024 samples/scan) and a time window of 60 ns. This multi-approach procedure allowed defining: (i) the housing of the tomb in the basement structure; (ii) the presence of a hidden corridor; (iii) the description of the internal structure of the walls of the tomb; (iv) the state of preservation of the monument. Acknowledgements: This work is co-financed by the European Union through the European Regional Development Fund under COMPETE 2020 (Operational Program for Competitiveness and Internationalization) through the ICT project (UID / GEO / 04683/2013) under the reference POCI-01-0145 -FEDER-007690.

  2. Interpretation of Late Cretaceous Volcanic Mounds and Surrounding Gulfian Series Formations Using 3D Seismic Data in Zavala County, Texas

    NASA Astrophysics Data System (ADS)

    Bennett, Laura Claire

    The Late Cretaceous Gulfian series is a prominent and important series across the State of Texas that has been extensively studied since the nineteenth century. It is composed of series of southeast-dipping shelf carbonates and clastics deposited on the northwest margin of the Gulf of Mexico Basin. In south Texas, the Gulfian series was deposited in the Rio Grande Embayment and Maverick Basin and is comprised of the Eagle Ford Group, Austin Group, Anacacho Limestone, San Miguel Formation, Olmos Formation, and Escondido Formation that crop out and continue basinward in the subsurface. Late Cretaceous volcanism formed volcanic mounds composed of altered palagonite tuff that are clustered into two fields, including the Uvalde Field centered in Zavala County. Using the Pedernales 3D seismic survey, located in east-central Zavala County, several volcanic mounds were identified and mapped without the use of well log data by identifying structures and characteristics associated with the volcanic mounds. Isolating these mounds through mapping enabled the mapping of the tops surrounding Gulfian formations, Lower Eagle Ford, Upper Eagle Ford, Austin, Anacacho, and San Miguel, for which time-structure, amplitude, similarity/coherency attribute, and isochron maps were generated. By using 3D seismic data, the volcanic mounds and their relation to surrounding rocks can be better interpreted.

  3. Rock formation characterization for carbon dioxide geosequestration: 3D seismic amplitude and coherency anomalies, and seismic petrophysical facies classification, Wellington and Anson-Bates Fields, Kansas, USA

    NASA Astrophysics Data System (ADS)

    Ohl, Derek; Raef, Abdelmoneam

    2014-04-01

    Higher resolution rock formation characterization is of paramount priority, amid growing interest in injecting carbon dioxide, CO2, into subsurface rock formations of depeleting/depleted hydrocarbon reservoirs or saline aquifers in order to reduce emissions of greenhouse gases. In this paper, we present a case study for a Mississippian carbonate characterization integrating post-stack seismic attributes, well log porosities, and seismic petrophysical facies classification. We evaluated changes in petrophysical lithofacies and reveal structural facies-controls in the study area. Three cross-plot clusters in a plot of well log porosity and acoustic impedance corroborated a Neural Network petrophysical facies classification, which was based on training and validation utilizing three petrophysically-different wells and three volume seismic attributes, extracted from a time window including the wavelet of the reservoir-top reflection. Reworked lithofacies along small-throw faults has been revealed based on comparing coherency and seismic petrophysical facies. The main objective of this study is to put an emphasis on reservoir characterization that is both optimized for and subsequently benefiting from pilot tertiary CO2 carbon geosequestration in a depleting reservoir and also in the deeper saline aquifer of the Arbuckle Group, south central Kansas. The 3D seismic coherency attribute, we calculated from a window embracing the Mississippian top reflection event, indicated anomalous features that can be interpreted as a change in lithofacies or faulting effect. An Artificial Neural Network (ANN) lithofacies modeling has been used to better understand these subtle features, and also provide petrophysical classes, which will benefit flow-simulation modeling and/or time-lapse seismic monitoring feasibility analysis. This paper emphasizes the need of paying greater attention to small-scale features when embarking upon characterization of a reservoir or saline-aquifer for CO2

  4. A western gray whale mitigation and monitoring program for a 3-D seismic survey, Sakhalin Island, Russia.

    PubMed

    Johnson, S R; Richardson, W J; Yazvenko, S B; Blokhin, S A; Gailey, G; Jenkerson, M R; Meier, S K; Melton, H R; Newcomer, M W; Perlov, A S; Rutenko, S A; Würsig, B; Martin, C R; Egging, D E

    2007-11-01

    The introduction of anthropogenic sounds into the marine environment can impact some marine mammals. Impacts can be greatly reduced if appropriate mitigation measures and monitoring are implemented. This paper concerns such measures undertaken by Exxon Neftegas Limited, as operator of the Sakhalin-1 Consortium, during the Odoptu 3-D seismic survey conducted during 17 August-9 September 2001. The key environmental issue was protection of the critically endangered western gray whale (Eschrichtius robustus), which feeds in summer and fall primarily in the Piltun feeding area off northeast Sakhalin Island. Existing mitigation and monitoring practices for seismic surveys in other jurisdictions were evaluated to identify best practices for reducing impacts on feeding activity by western gray whales. Two buffer zones were established to protect whales from physical injury or undue disturbance during feeding. A 1 km buffer protected all whales from exposure to levels of sound energy potentially capable of producing physical injury. A 4-5 km buffer was established to avoid displacing western gray whales from feeding areas. Trained Marine Mammal Observers (MMOs) on the seismic ship Nordic Explorer had the authority to shut down the air guns if whales were sighted within these buffers. Additional mitigation measures were also incorporated: Temporal mitigation was provided by rescheduling the program from June-August to August-September to avoid interference with spring arrival of migrating gray whales. The survey area was reduced by 19% to avoid certain waters <20 m deep where feeding whales concentrated and where seismic acquisition was a lower priority. The number of air guns and total volume of the air guns were reduced by about half (from 28 to 14 air guns and from 3,390 in(3) to 1,640 in(3)) relative to initial plans. "Ramp-up" (="soft-start") procedures were implemented. Monitoring activities were conducted as needed to implement some mitigation measures, and to assess

  5. Investigating the point seismic array concept with seismic rotation measurements.

    SciTech Connect

    Abbott, Robert E.; Aldridge, David Franklin

    2009-02-01

    Spatially-distributed arrays of seismometers are often utilized to infer the speed and direction of incident seismic waves. Conventionally, individual seismometers of the array measure one or more orthogonal components of rectilinear particle motion (displacement, velocity, or acceleration). The present work demonstrates that measure of both the particle velocity vector and the particle rotation vector at a single point receiver yields sufficient information to discern the type (compressional or shear), speed, and direction of an incident plane seismic wave. Hence, the approach offers the intriguing possibility of dispensing with spatially-extended received arrays, with their many problematic deployment, maintenance, relocation, and post-acquisition data processing issues. This study outlines straightforward mathematical theory underlying the point seismic array concept, and implements a simple cross-correlation scanning algorithm for determining the azimuth of incident seismic waves from measured acceleration and rotation rate data. The algorithm is successfully applied to synthetic seismic data generated by an advanced finite-difference seismic wave propagation modeling algorithm. Application of the same azimuth scanning approach to data acquired at a site near Yucca Mountain, Nevada yields ambiguous, albeit encouraging, results. Practical issues associated with rotational seismometry are recognized as important, but are not addressed in this investigation.

  6. 3-D seismic data for field development: Landslide field case study

    SciTech Connect

    Raeuchle, S.K.; Carr, T.R.; Tucker, R.D. )

    1990-05-01

    The Landslide field is located on the extreme southern flank of the San Joaquin basin, approximately 25 mi south of Bakersfield, California. The field, discovered in 1985, has produced in excess 9 million bbl of oil with an estimated ultimate recovery of more than 13 MMBO. The Miocene Stevens sands, which form the reservoir units at Landslide field, are interpreted as a series of constructional submarine fan deposits. Deposition of the fans was controlled by paleotopography with an abrupt updip pinch-out of the sands to the southwest. The three-dimensional seismic data over the field was used to locate the bottom hole of the landslide 22X-30 development well as close to this abrupt updip pinchout as possible in order to maximize oil recovery. A location was selected two traces (330 ft) from the updip pinch-out as mapped on the seismic data. The well was successfully drilled during 1989, encountering 150 ft of net sand with initial production in excess of 1,500 bbl of oil/day. A pressure buildup test indicates the presence of a boundary approximately 200 ft from the well bore. This boundary is interpreted as the updip pinchout of the Stevens sands against the paleohigh. Based on examination of changes in amplitude, the absence or presence of reservoir-quality sand can be mapped across the paleohighs. Application of three-dimensional seismic data, integration with well data, and in particular reconstruction cuts tied closely to existing wells can be used to map the ultimate extent of the field and contribute to efficient development.

  7. 3D reflection seismic imaging at the 2.5 km deep COSC-1 scientific borehole, central Scandinavian Caledonides

    NASA Astrophysics Data System (ADS)

    Hedin, Peter; Almqvist, Bjarne; Berthet, Théo; Juhlin, Christopher; Buske, Stefan; Simon, Helge; Giese, Rüdiger; Krauß, Felix; Rosberg, Jan-Erik; Alm, Per-Gunnar

    2016-10-01

    The 2.5 km deep scientific COSC-1 borehole (ICDP 5054-1-A) was successfully drilled with nearly complete core recovery during spring and summer of 2014. Downhole and on-core measurements through the targeted Lower Seve Nappe provide a comprehensive data set. An observed gradual increase in strain below 1700 m, with mica schists and intermittent mylonites increasing in frequency and thickness, is here interpreted as the basal thrust zone of the Lower Seve Nappe. This high strain zone was not fully penetrated at the total drilled depth and is thus greater than 800 m in thickness. To allow extrapolation of the results from downhole logging, core analysis and other experiments into the surrounding rock and to link these with the regional tectonic setting and evolution, three post-drilling high-resolution seismic experiments were conducted in and around the borehole. One of these, the first 3D seismic reflection land survey to target the nappe structures of the Scandinavian Caledonides, is presented here. It provides new information on the 3D geometry of structures both within the drilled Lower Seve Nappe and underlying rocks down to at least 9 km. The observed reflectivity correlates well with results from the core analysis and downhole logging, despite challenges in processing. Reflections from the uppermost part of the Lower Seve Nappe have limited lateral extent and varying dips, possibly related to mafic lenses or boudins of variable character within felsic rock. Reflections occurring within the high strain zone, however, are laterally continuous over distances of a kilometer or more and dip 10-15° towards the southeast. Reflections from structures beneath the high strain unit and the COSC-1 borehole can be followed through most of the seismic volume down to at least 9 km and have dips of varying degree, mainly in the east-west thrust direction of the orogen.

  8. Reducing Disk Storage of Full-3D Seismic Waveform Tomography (F3DT) Through Lossy Online Compression

    DOE PAGES

    Lindstrom, Peter; Chen, Po; Lee, En-Jui

    2016-05-05

    Full-3D seismic waveform tomography (F3DT) is the latest seismic tomography technique that can assimilate broadband, multi-component seismic waveform observations into high-resolution 3D subsurface seismic structure models. The main drawback in the current F3DT implementation, in particular the scattering-integral implementation (F3DT-SI), is the high disk storage cost and the associated I/O overhead of archiving the 4D space-time wavefields of the receiver- or source-side strain tensors. The strain tensor fields are needed for computing the data sensitivity kernels, which are used for constructing the Jacobian matrix in the Gauss-Newton optimization algorithm. In this study, we have successfully integrated a lossy compression algorithmmore » into our F3DT SI workflow to significantly reduce the disk space for storing the strain tensor fields. The compressor supports a user-specified tolerance for bounding the error, and can be integrated into our finite-difference wave-propagation simulation code used for computing the strain fields. The decompressor can be integrated into the kernel calculation code that reads the strain fields from the disk and compute the data sensitivity kernels. During the wave-propagation simulations, we compress the strain fields before writing them to the disk. To compute the data sensitivity kernels, we read the compressed strain fields from the disk and decompress them before using them in kernel calculations. Experiments using a realistic dataset in our California statewide F3DT project have shown that we can reduce the strain-field disk storage by at least an order of magnitude with acceptable loss, and also improve the overall I/O performance of the entire F3DT-SI workflow significantly. The integration of the lossy online compressor may potentially open up the possibilities of the wide adoption of F3DT-SI in routine seismic tomography practices in the near future.« less

  9. A Revised Stress Map of the Conterminous United States and Causal Links Between 3-D Density Structure and Intraplate Seismicity

    NASA Astrophysics Data System (ADS)

    Levandowski, W. B.; Shen, W.; Briggs, R. W.; Boyd, O. S.

    2016-12-01

    In the past decade, both seismic networks such as the Transportable Array and induced seismicity have provided an unprecedented number of earthquake moment tensors across the conterminous United States, allowing appraisal of the state of stress with ever-greater accuracy and spatial resolution. We invert 1896 moment tensors for the best-fitting stress tensor in each of 29 geographic subprovinces. Here, we focus on novel results from the central and eastern U.S. (CEUS). At the broadest scale, maximum horizontal compression rotates from NE-SW in the Northeast to ENE-WSW in the Midwest, and to E-W on the Great Plains as the style of faulting grades from thrust to strike-slip to normal. Yet contrary to common assertion, statistically significant differences exist between adjacent subprovinces. Principal stress rotations of up to 45° and changes in Aϕ of up to 1 (e.g., a switch from pure normal faulting to pure strike-slip faulting) occur over as little as 10s of km. Such differences have a profound impact on what fault orientations are compatible with slip slip. Forces applied at the plate edges or base cannot explain changes over such short distances; the cause must be internal to the lithosphere. To map these body forces across the conterminous United States, we use seismic velocity, gravity, topography, and heat flow to estimate 3-D density structure. Then finite-element modeling quantifies gravity-derived deviatoric loads and their interactions with far-field stress. The tensor sum of gravity-derived and plate-boundary stress generally reproduces variations observed independently in moment tensors. Moreover, seismicity—both natural and induced—focuses in regions of elevated stress, in particular the New Madrid and Eastern Tennessee seismic zones, Oklahoma and southcentral Kansas, and along the Rocky Mountain Front. These results suggest that by quantifying the net fault loading tensor, it becomes possible to determine whether any known or hypothesized fault

  10. 3D seismic velocity structure in the rupture area of the 2014 M8.2 Iquique earthquake in Northern Chile

    NASA Astrophysics Data System (ADS)

    Woollam, Jack; Fuenzallida, Amaya; Garth, Tom; Rietbrock, Andreas; Ruiz, Sergio; Tavera, Hernando

    2016-04-01

    Seismic velocity tomography is one of the key tools in Earth sciences to image the physical properties of the subsurface. In recent years significant advances have been made to image the Chilean subductions zone, especially in the area of the 2010 M8.8 Maule earthquake (e.g. Hicks et al., 2014), providing much needed physical constraints for earthquakes source inversions and rupture models. In 2014 the M8.2 Iquique earthquake struck the northern part of the Chilean subduction zone in close proximity to the Peruvian boarder. The pre- and aftershock sequence of this major earthquake was recorded by a densified seismological network in Northern Chile and Southern Peru, which provides an excellent data set to study in depth the 3D velocity structure along the subduction megathrust. Based on an automatic event catalogue of nearly 10,000 events spanning the time period March to May 2014 we selected approximately 450 events for a staggered 3D inversion approach. Events are selected to guarantee an even ray coverage through the inversion volume. We only select events with a minimum GAP of 200 to improve depth estimates and therefore increase resolution in the marine forearc. Additionally, we investigate secondary arrivals between the P- and S-wave arrival to improve depth location. Up to now we have processed about 450 events, from which about 150 with at least 30 P- and S-wave observations have been selected for the subsequent 3D tomography. Overall the data quality is very high, which allows arrival time estimates better than 0.05s on average. We will show results from the 1D, 2D, and preliminary 3D inversions and discuss the results together with the obtained seismicity distribution.

  11. Subsurface fault geometries in Southern California illuminated through Full-3D Seismic Waveform Tomography (F3DT)

    NASA Astrophysics Data System (ADS)

    Lee, En-Jui; Chen, Po

    2017-04-01

    More precise spatial descriptions of fault systems play an essential role in tectonic interpretations, deformation modeling, and seismic hazard assessments. The recent developed full-3D waveform tomography techniques provide high-resolution images and are able to image the material property differences across faults to assist the understanding of fault systems. In the updated seismic velocity model for Southern California, CVM-S4.26, many velocity gradients show consistency with surface geology and major faults defined in the Community Fault Model (CFM) (Plesch et al. 2007), which was constructed by using various geological and geophysical observations. In addition to faults in CFM, CVM-S4.26 reveals a velocity reversal mainly beneath the San Gabriel Mountain and Western Mojave Desert regions, which is correlated with the detachment structure that has also been found in other independent studies. The high-resolution tomographic images of CVM-S4.26 could assist the understanding of fault systems in Southern California and therefore benefit the development of fault models as well as other applications, such as seismic hazard analysis, tectonic reconstructions, and crustal deformation modeling.

  12. 3D crustal seismic velocity model for the Gulf of Cadiz and adjacent areas (SW Iberia margin) based on seismic reflection and refraction profiles

    NASA Astrophysics Data System (ADS)

    Lozano, Lucía; Cantavella, Juan Vicente; Barco, Jaime; Carranza, Marta; Burforn, Elisa

    2016-04-01

    The Atlantic margin of the SW Iberian Peninsula and northern Morocco has been subject of study during the last 30 years. Many seismic reflection and refraction profiles have been carried out offshore, providing detailed information about the crustal structure of the main seafloor tectonic domains in the region, from the South Portuguese Zone and the Gulf of Cadiz to the Abyssal Plains and the Josephine Seamount. The interest to obtain a detailed and realistic velocity model for this area, integrating the available data from these studies, is clear, mainly to improve real-time earthquake hypocentral location and for tsunami and earthquake early warning. Since currently real-time seismic location tools allow the implementation of 3D velocity models, we aim to generate a full 3D crustal model. For this purpose we have reviewed more than 50 profiles obtained in different seismic surveys, from 1980 to 2008. Data from the most relevant and reliable 2D seismic velocity published profiles were retrieved. We first generated a Moho depth map of the studied area (latitude 32°N - 41°N and longitude 15°W - 5°W) by extracting Moho depths along each digitized profile with a 10 km spacing, and then interpolating this dataset using ordinary kriging method and generating the contour isodepth map. Then, a 3D crustal velocity model has been obtained. Selected vertical sections at different distances along each profile were considered to retrieve P-wave velocity values at each interface in order to reproduce the geometry and the velocity gradient within each layer. A double linear interpolation, both in distance and depth, with sampling rates of 10 km and 1 km respectively, was carried out to generate a (latitude, longitude, depth, velocity) matrix. This database of all the profiles was interpolated to obtain the P-wave velocity distribution map every kilometer of depth. The new 3D velocity model has been integrated in NonLinLoc location program to relocate several representative

  13. Bayesian Inference of Seismic Sources Using a 3-D Earth Model for the Japanese Islands Region

    NASA Astrophysics Data System (ADS)

    Simutė, Saulė; Fichtner, Andreas

    2017-04-01

    Earthquake source inversion is an established problem in seismology. Nevertheless, one-dimensional Earth models are commonly used to compute synthetic data in point- as well as finite-fault inversions. Reliance on simplified Earth models limits the exploitable information to longer periods and as such, contributes to notorious non-uniqueness of finite-fault models. Failure to properly account for Earth structure means that inaccuracies in the Earth model can map into and pollute the earthquake source solutions. To tackle these problems we construct a full-waveform 3-D Earth model for the Japanese Islands region and infer earthquake source parameters in a probabilistic way using numerically computed 3-D Green's functions. Our model explains data from the earthquakes not used in the inversion significantly better than the initial model in the period range of 20-80 s. This indicates that the model is not over-fit and may thus be used for improved earthquake source inversion. To solve the forward problem, we pre-compute and store Green's functions with the spectral element solver SES3D for all potential source-receiver pairs. The exploitation of the Green's function database means that the forward problem of obtaining displacements is merely a linear combination of strain Green's tensor scaled by the moment tensor elements. We invert for ten model parameters - six moment tensors elements, three location parameters, and the time of the event. A feasible number of model parameters and the fast forward problem allow us to infer the unknowns using the Bayesian Markov chain Monte Carlo, which results in the marginal posterior distributions for every model parameter. The Monte Carlo algorithm is validated against analytical solutions for the linear test case. We perform the inversions using real data in the Japanese Islands region and assess the quality of the solutions by comparing the obtained results with those from the existing 1-D catalogues.

  14. 3D elastic full waveform inversion: case study from a land seismic survey

    NASA Astrophysics Data System (ADS)

    Kormann, Jean; Marti, David; Rodriguez, Juan-Esteban; Marzan, Ignacio; Ferrer, Miguel; Gutierrez, Natalia; Farres, Albert; Hanzich, Mauricio; de la Puente, Josep; Carbonell, Ramon

    2016-04-01

    Full Waveform Inversion (FWI) is one of the most advanced processing methods that is recently reaching a mature state after years of solving theoretical and technical issues such as the non-uniqueness of the solution and harnessing the huge computational power required by realistic scenarios. BSIT (Barcelona Subsurface Imaging Tools, www.bsc.es/bsit) includes a FWI algorithm that can tackle with very complex problems involving large datasets. We present here the application of this system to a 3D dataset acquired to constrain the shallow subsurface. This is where the wavefield is the most complicated, because most of the wavefield conversions takes place in the shallow region and also because the media is much more laterally heterogeneous. With this in mind, at least isotropic elastic approximation would be suitable as kernel engine for FWI. The current study explores the possibilities to apply elastic isotropic FWI using only the vertical component of the recorded seismograms. The survey covers an area of 500×500 m2, and consists in a receivers grid of 10 m×20 m combined with a 250 kg accelerated weight-drop as source on a displaced grid of 20 m×20 m. One of the main challenges in this case study is the costly 3D modeling that includes topography and substantial free surface effects. FWI is applied to a data subset (shooting lines 4 to 12), and is performed for 3 frequencies ranging from 15 to 25 Hz. The starting models are obtained from travel-time tomography and the all computation is run on 75 nodes of Mare Nostrum supercomputer during 3 days. The resulting models provide a higher resolution of the subsurface structures, and show a good correlation with the available borehole measurements. FWI allows to extend in a reliable way this 1D knowledge (borehole) to 3D.

  15. 3D imaging of the Corinth rift from a new passive seismic tomography and receiver function analysis

    NASA Astrophysics Data System (ADS)

    Godano, Maxime; Gesret, Alexandrine; Noble, Mark; Lyon-Caen, Hélène; Gautier, Stéphanie; Deschamps, Anne

    2016-04-01

    The Corinth Rift is the most seismically active zone in Europe. The area is characterized by very localized NS extension at a rate of ~ 1.5cm/year, the occurrence of frequent and intensive microseismic crises and occasional moderate to large earthquakes like in 1995 (Mw=6.1). Since the year 2000, the Corinth Rift Laboratory (CRL, http://crlab.eu) consisting in a multidisciplinary natural observatory, aims at understanding the mechanics of faulting and earthquake nucleation in the Rift. Recent studies have improved our view about fault geometry and mechanics within CRL, but there is still a critical need for a better knowledge of the structure at depth both for the accuracy of earthquake locations and for mechanical interpretation of the seismicity. In this project, we aim to analyze the complete seismological database (13 years of recordings) of CRL by using recently developed methodologies of structural imaging, in order to determine at the same time and with high resolution, the local 3D structure and the earthquake locations. We perform an iterative joint determination of 3D velocity model and earthquake coordinates. In a first step, P and S velocity models are determined using first arrival time tomography method proposed by Taillandier et al. (2009). It consists in the minimization of the cost function between observed and theoretical arrival times which is achieved by the steepest descent method (e.g. Tarantola 1987). This latter requires computing the gradient of the cost function by using the adjoint state method (Chavent 1974). In a second step, earthquakes are located in the new velocity model with a non-linear inversion method based on a Bayesian formulation (Gesret et al. 2015). Step 1 and 2 are repeated until the cost function no longer decreases. We present preliminary results consisting in: (1) the adjustement of a 1D velocity model that is used as initial model of the 3D tomography and (2) a first attempt of the joint determination of 3D velocity

  16. Estimating the composition of hydrates from a 3D seismic dataset near Penghu Canyon on Chinese passive margin offshore Taiwan

    NASA Astrophysics Data System (ADS)

    Chi, Wu-Cheng

    2016-04-01

    A bottom-simulating reflector (BSR), representing the base of the gas hydrate stability zone, can be used to estimate geothermal gradients under seafloor. However, to derive temperature estimates at the BSR, the correct hydrate composition is needed to calculate the phase boundary. Here we applied the method by Minshull and Keddie to constrain the hydrate composition and the pore fluid salinity. We used a 3D seismic dataset offshore SW Taiwan to test the method. Different from previous studies, we have considered the effects of 3D topographic effects using finite element modelling and also depth-dependent thermal conductivity. Using a pore water salinity of 2% at the BSR depth as found from the nearby core samples, we successfully used 99% methane and 1% ethane gas hydrate phase boundary to derive a sub-bottom depth vs. temperature plot which is consistent with the seafloor temperature from in-situ measurements. The results are also consistent with geochemical analyses of the pore fluids. The derived regional geothermal gradient is 40.1oC/km, which is similar to 40oC/km used in the 3D finite element modelling used in this study. This study is among the first documented successful use of Minshull and Keddie's method to constrain seafloor gas hydrate composition.

  17. Investigation Into the Utilization of 3D Printing in Laser Cooling Experiments

    NASA Astrophysics Data System (ADS)

    Hazlett, Eric

    With the advancement of 3D printing new opportunities are abound in many different fields, but with the balance between the precisions of atomic physics experiments and the material properties of current 3D printers the benefit of 3D printing technology needs to be investigated. We report on the progress of two investigations of 3D printing of benefit to atomic physics experiments: laser feedback module and the other being an optical chopper. The first investigation looks into creation of a 3D printed laser diode feedback module. This 3D printed module would allow for the quick realization of an external cavity diode laser that would have an adjustable cavity distance. We will report on the first tests of this system, by looking at Rb spectroscopy and mode-hop free tuning range as well as possibilities of using these lasers for MOT generation. We will also discuss our investigation into a 3D-printed optical chopper that utilizes an Arduino and a computer hard drive motor. By implementing an additional Arduino we create a low cost way to quickly measure laser beam waists

  18. Investigation Into the Utilization of 3D Printing in Laser Cooling Experiments

    NASA Astrophysics Data System (ADS)

    Hazlett, Eric; Nelson, Brandon; de Leon, Sam Diaz; Shaw, Jonah

    2016-05-01

    With the advancement of 3D printing new opportunities are abound in many different fields, but with the balance between the precisions of atomic physics experiments and the material properties of current 3D printers the benefit of 3D printing technology needs to be investigated. We report on the progress of two investigations of 3D printing of benefit to atomic physics experiments: laser feedback module and the other being an optical chopper. The first investigation looks into creation of a 3D printed laser diode feedback module. This 3D printed module would allow for the quick realization of an external cavity diode laser that would have an adjustable cavity distance. We will report on the first tests of this system, by looking at Rb spectroscopy and mode-hop free tuning range as well as possibilities of using these lasers for MOT generation. We will also discuss our investigation into a 3D-printed optical chopper that utilizes an Arduino and a computer hard drive motor. By implementing an additional Arduino we create a low cost way to quickly measure laser beam waists.

  19. High-resolution 3D seismic imaging of the Longmenshan fault zone structure using double-difference seismic tomography

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yu, X.; Zhang, W.

    2011-12-01

    The Longmenshan fault zone where the 2008 M8.0 Wenchuan, China, earthquake occurred is located in the boundary area between the Songpan-Garze block to the west and the Sichuan basin to the east. This area is characterized by complex structures and active seismotectonics. We collected both direct P wave absolute arrival times and differential arrival times from 2551 events in the period of 1992 to 1999 recorded by China National Seismic Network. The double-difference seismic tomography (tomoDD) method is used to determine event relocations and the P wave crustal and upper mantle velocity structure. Our results show that obvious velocity variations exist in the crust and upper mantle beneath the Longmenshan fault zone. The inferred velocity structure of the upper crust correlates well with the surface geological and topographic features in this area: the east of Tibet plateau is imaged as a prominent high-velocity zone, while the Longmenshan fault and Sichuan basin are imaged as a low-velocity feature. Compared with upper crust, the Longmenshan fault zone lies in the transition zone between high velocity anomalies to the west and low velocity anomalies to the east in the middle crust, where most earthquakes occurred. While in the lower crust, the fault zone lies in the transition zone between low velocity anomalies to the west and high velocity anomalies to the east. In upper mantle, a prominent low velocity anomaly exists under the Wenchuan main shock region. This suggests that lower crustal flow has affect on the occurrence of the Wenchuan earthquake. There is also a obvious velocity structure difference between the south and north segment of the Longmenshan fault zone in the whole crust and upper mantle, low velocity anomalies in the south segment and prominent lateral heterogeneous in the north segment, respectively. The velocity difference maybe resulted in the northeastwards of the Wenchuan aftershocks.

  20. 3D seismic imaging of voluminous earliest Eocene buried lava fields and coastal escarpments off mid-Norway

    NASA Astrophysics Data System (ADS)

    Planke, Sverre; Millett, John M.; Maharjan, Dwarika; Jerram, Dougal A.; Mansour Abdelmalak, Mohamed

    2017-04-01

    Continental breakup between Greenland and NW Europe in the Paleogene was associated with massive basaltic volcanism, forming kilometer-thick sequences of flood basalts along the conjugate rifted margins. This event was temporarily associated with a warm world, the early Eocene greenhouse, and the short-lived Paleocene-Eocene Thermal Maximum (PETM). A 2500 km2 large industry-standard 3D seismic cube has recently been acquired on the Vøring Marginal High offshore mid-Norway to image sub-basalt sedimentary rocks. This cube also provides a unique opportunity for imaging top- and intra-basalt structures. Detailed seismic geomorphological interpretation of the Top basalt horizon reveal new insight into the late-stage development of the lava flow fields and the kilometer high coastal Vøring Escarpment. Subaerial lava flows with compressional ridges and inflated lava lobes cover the marginal high, with comparable structure and size to modern subaerial lava fields. Pitted surfaces, likely formed by lava emplaced in a wet environment, are present in the western part of the study area near the continent-ocean boundary. The prominent Vøring Escarpment formed when eastward-flowing lava reached the coastline. The escarpment morphology is influenced by pre-existing structural highs, and locally these highs are by-passed by the lava flows which are clearly deflected around them. Volcanogenic debris flows are well-imaged on the escarpment horizon along with large-scale slump blocks. Similar features exist in active volcanic environments, e.g. on the south coast of Hawaii. Numerous post-volcanic extensional faults and incised channels cut both into the marginal high and the escarpment, and show that the area was geologically active after the volcanism ceased. In conclusion, igneous seismic geomorphology and seismic volcanostratigraphy are two very powerful methods to understand the volcanic deposits and development of rifted margins, and the association of major volcanic events

  1. Calibration of 3D Upper Mantle Structure in Eurasia Using Regional and Teleseismic Full Waveform Seismic Data

    SciTech Connect

    Barbara Romanowicz; Mark Panning

    2005-04-23

    Adequate path calibrations are crucial for improving the accuracy of seismic event location and origin time, size, and mechanism, as required for CTBT monitoring. There is considerable information on structure in broadband seismograms that is currently not fully utilized. The limitations have been largely theoretical. the development and application to solid earth problems of powerful numerical techniques, such as the Spectral Element Method (SEM), has opened a new era, and theoretically, it should be possible to compute the complete predicted wavefield accurately without any restrictions on the strength or spatial extent of heterogeneity. This approach requires considerable computational power, which is currently not fully reachable in practice. We propose an approach which relies on a cascade of increasingly accurate theoretical approximations for the computation of the seismic wavefield to develop a model of regional structure for the area of Eurasia located between longitudes of 30 and 150 degrees E, and latitudes of -10 to 60 degrees North. The selected area is particularly suitable for the purpose of this experiment, as it is highly heterogeneous, presenting a challenge for calibration purposes, but it is well surrounded by earthquake sources and, even though they are sparsely distributed, a significant number of high quality broadband digital stations exist, for which data are readily accessible through IRIS (Incorporated Research Institutions for Seismology) and the FDSN (Federation of Digital Seismic Networks). The starting models used will be a combination of a-priori 3D models recently developed for this region, combining various geophysical and seismological data, and a major goal of this study will be to refine these models so as to fit a variety of seismic waveforms and phases.

  2. Improving Geologic and Engineering Models of Midcontinent Fracture and Karst-Modified Reservoirs Using New 3-D Seismic Attributes

    SciTech Connect

    Susan Nissen; Saibal Bhattacharya; W. Lynn Watney; John Doveton

    2009-03-31

    Our project goal was to develop innovative seismic-based workflows for the incremental recovery of oil from karst-modified reservoirs within the onshore continental United States. Specific project objectives were: (1) to calibrate new multi-trace seismic attributes (volumetric curvature, in particular) for improved imaging of karst-modified reservoirs, (2) to develop attribute-based, cost-effective workflows to better characterize karst-modified carbonate reservoirs and fracture systems, and (3) to improve accuracy and predictiveness of resulting geomodels and reservoir simulations. In order to develop our workflows and validate our techniques, we conducted integrated studies of five karst-modified reservoirs in west Texas, Colorado, and Kansas. Our studies show that 3-D seismic volumetric curvature attributes have the ability to re-veal previously unknown features or provide enhanced visibility of karst and fracture features compared with other seismic analysis methods. Using these attributes, we recognize collapse features, solution-enlarged fractures, and geomorphologies that appear to be related to mature, cockpit landscapes. In four of our reservoir studies, volumetric curvature attributes appear to delineate reservoir compartment boundaries that impact production. The presence of these compartment boundaries was corroborated by reservoir simulations in two of the study areas. Based on our study results, we conclude that volumetric curvature attributes are valuable tools for mapping compartment boundaries in fracture- and karst-modified reservoirs, and we propose a best practices workflow for incorporating these attributes into reservoir characterization. When properly calibrated with geological and production data, these attributes can be used to predict the locations and sizes of undrained reservoir compartments. Technology transfer of our project work has been accomplished through presentations at professional society meetings, peer-reviewed publications

  3. Understanding the paleo environment in the Danish North Sea using 2D and 3D seismic analyses

    NASA Astrophysics Data System (ADS)

    Prins, Lasse K.; Clausen, Ole R.; Andresen, Katrine J.

    2017-04-01

    This study presents the first detailed and integrated mapping of buried Quaternary valleys, river systems and iceberg scourings from the Danish North Sea region. The mapped features coincide spatially but have very different characteristics and incision levels which allow us to constrain their relative timing and differentiate their environment of formation (subglacial, proglacial and marine). The results of the study bring new critical information regarding the paleoenvironment of the North Sea Basin during the latest Quaternary deglaciation period and our analysis provide a well-tested workflow for utilizing 2D and 3D seismic data in relation to paleogeographical reconstructions. Our analysis is based on interpretation of conventional 3D seismic and high-resolution sparker data from the Southern Danish Central Graben. The project forms part of the portfolio for the 'Danish Hydrocarbon Research and Technology Centre' and aims at building a high-resolution 3D geological-geotechnical model of the shallow subsurface by using geophysical data combined with geological and geotechnical data from shallow borings. One of the objectives is to map potential geohazards for offshore installations such as buried valleys and constrain their geotechnical properties. The central North Sea is known to have been covered by glaciers several times during the Quaternary with climate changing between arctic and boreal. Marine conditions periodically prevailed and large river systems mainly from central Europe dominated during periods of subaerial exposure. Hence, many buried erosional incisions, primarily tunnel valleys but also river systems, can be observed within the upper 200-400 meters of the Quaternary succession throughout the central North Sea region. A high-resolution mapping of the infill of the tunnel valleys and river systems have however not previously been presented. Our analysis shows that within the study area at least four generations of tunnel valley formation and

  4. INCREASING OIL RECOVERY THROUGH ADVANCED REPROCESSING OF 3D SEISMIC, GRANT CANYON AND BACON FLAT FIELDS, NYE COUNTY, NEVADA

    SciTech Connect

    Eric H. Johnson; Don E. French

    2001-06-01

    Makoil, Inc., of Orange, California, with the support of the U.S. Department of Energy has reprocessed and reinterpreted the 3D seismic survey of the Grant Canyon area, Railroad Valley, Nye County, Nevada. The project was supported by Dept. of Energy Grant DE-FG26-00BC15257. The Grant Canyon survey covers an area of 11 square miles, and includes Grant Canyon and Bacon Flat oil fields. These fields have produced over 20 million barrels of oil since 1981, from debris slides of Devonian rocks that are beneath 3,500 to 5,000 ft of Tertiary syntectonic deposits that fill the basin of Railroad Valley. High-angle and low-angle normal faults complicate the trap geometry of the fields, and there is great variability in the acoustic characteristics of the overlying valley fill. These factors combine to create an area that is challenging to interpret from seismic reflection data. A 3D seismic survey acquired in 1992-93 by the operator of the fields has been used to identify development and wildcat locations with mixed success. Makoil believed that improved techniques of processing seismic data and additional well control could enhance the interpretation enough to improve the chances of success in the survey area. The project involved the acquisition of hardware and software for survey interpretation, survey reprocessing, and reinterpretation of the survey. SeisX, published by Paradigm Geophysical Ltd., was chosen as the interpretation software, and it was installed on a Dell Precision 610 computer work station with the Windows NT operating system. The hardware and software were selected based on cost, possible addition of compatible modeling software in the future, and the experience of consulting geophysicists in the Billings area. Installation of the software and integration of the hardware into the local office network was difficult at times but was accomplished with some technical support from Paradigm and Hewlett Packard, manufacturer of some of the network equipment. A

  5. Pseudo 3-D P wave refraction seismic monitoring of permafrost in steep unstable bedrock

    NASA Astrophysics Data System (ADS)

    Krautblatter, Michael; Draebing, Daniel

    2014-02-01

    permafrost in steep rock walls can cause hazardous rock creep and rock slope failure. Spatial and temporal patterns of permafrost degradation that operate at the scale of instability are complex and poorly understood. For the first time, we used P wave seismic refraction tomography (SRT) to monitor the degradation of permafrost in steep rock walls. A 2.5-D survey with five 80 m long parallel transects was installed across an unstable steep NE-SW facing crestline in the Matter Valley, Switzerland. P wave velocity was calibrated in the laboratory for water-saturated low-porosity paragneiss samples between 20°C and -5°C and increases significantly along and perpendicular to the cleavage by 0.55-0.66 km/s (10-13%) and 2.4-2.7 km/s (>100%), respectively, when freezing. Seismic refraction is, thus, technically feasible to detect permafrost in low-porosity rocks that constitute steep rock walls. Ray densities up to 100 and more delimit the boundary between unfrozen and frozen bedrock and facilitate accurate active layer positioning. SRT shows monthly (August and September 2006) and annual active layer dynamics (August 2006 and 2007) and reveals a contiguous permafrost body below the NE face with annual changes of active layer depth from 2 to 10 m. Large ice-filled fractures, lateral onfreezing of glacierets, and a persistent snow cornice cause previously unreported permafrost patterns close to the surface and along the crestline which correspond to active seasonal rock displacements up to several mm/a. SRT provides a geometrically highly resolved subsurface monitoring of active layer dynamics in steep permafrost rocks at the scale of instability.

  6. 3D seismic analysis of gravity-driven and basement influenced normal fault growth in the deepwater Otway Basin, Australia

    NASA Astrophysics Data System (ADS)

    Robson, A. G.; King, R. C.; Holford, S. P.

    2016-08-01

    We use three-dimensional (3D) seismic reflection data to analyse the structural style and growth of a normal fault array located at the present-day shelf-edge break and into the deepwater province of the Otway Basin, southern Australia. The Otway Basin is a Late Jurassic to Cenozoic, rift-to-passive margin basin. The seismic reflection data images a NW-SE (128-308) striking, normal fault array, located within Upper Cretaceous clastic sediments and which consists of ten fault segments. The fault array contains two hard-linked fault assemblages, separated by only 2 km in the dip direction. The gravity-driven, down-dip fault assemblage is entirely contained within the 3D seismic survey, is located over a basement plateau and displays growth commencing and terminating during the Campanian-Maastrichtian, with up to 1.45 km of accumulated throw (vertical displacement). The up-dip normal fault assemblage penetrates deeper than the base of the seismic survey, but is interpreted to be partially linked along strike at depth to major basement-involved normal faults that can be observed on regional 2D seismic lines. This fault assemblage displays growth initiating in the Turonian-Santonian and has accumulated up to 1.74 km of throw. Our detailed analysis of the 3D seismic data constraints post-Cenomanian fault growth of both fault assemblages into four evolutionary stages: [1] Turonian-Santonian basement reactivation during crustal extension between Australia and Antarctica. This either caused the upward propagation of basement-involved normal faults or the nucleation of a vertically isolated normal fault array in shallow cover sediments directly above the reactivated basement-involved faults; [2] continued Campanian-Maastrichtian crustal extension and sediment loading eventually created gravitational instability on the basement plateau, nucleating a second, vertically isolated normal fault array in the cover sediments; [3] eventual hard-linkage of fault segments in both fault

  7. Calculating the Probability of Strong Ground Motions Using 3D Seismic Waveform Modeling - SCEC CyberShake

    NASA Astrophysics Data System (ADS)

    Gupta, N.; Callaghan, S.; Graves, R.; Mehta, G.; Zhao, L.; Deelman, E.; Jordan, T. H.; Kesselman, C.; Okaya, D.; Cui, Y.; Field, E.; Gupta, V.; Vahi, K.; Maechling, P. J.

    2006-12-01

    Researchers from the SCEC Community Modeling Environment (SCEC/CME) project are utilizing the CyberShake computational platform and a distributed high performance computing environment that includes USC High Performance Computer Center and the NSF TeraGrid facilities to calculate physics-based probabilistic seismic hazard curves for several sites in the Southern California area. Traditionally, probabilistic seismic hazard analysis (PSHA) is conducted using intensity measure relationships based on empirical attenuation relationships. However, a more physics-based approach using waveform modeling could lead to significant improvements in seismic hazard analysis. Members of the SCEC/CME Project have integrated leading-edge PSHA software tools, SCEC-developed geophysical models, validated anelastic wave modeling software, and state-of-the-art computational technologies on the TeraGrid to calculate probabilistic seismic hazard curves using 3D waveform-based modeling. The CyberShake calculations for a single probablistic seismic hazard curve require tens of thousands of CPU hours and multiple terabytes of disk storage. The CyberShake workflows are run on high performance computing systems including multiple TeraGrid sites (currently SDSC and NCSA), and the USC Center for High Performance Computing and Communications. To manage the extensive job scheduling and data requirements, CyberShake utilizes a grid-based scientific workflow system based on the Virtual Data System (VDS), the Pegasus meta-scheduler system, and the Globus toolkit. Probabilistic seismic hazard curves for spectral acceleration at 3.0 seconds have been produced for eleven sites in the Southern California region, including rock and basin sites. At low ground motion levels, there is little difference between the CyberShake and attenuation relationship curves. At higher ground motion (lower probability) levels, the curves are similar for some sites (downtown LA, I-5/SR-14 interchange) but different for

  8. The Role of Faulting on the Growth of a Carbonate Platform: Evidence from 3D Seismic Analysis and Section Restoration

    NASA Astrophysics Data System (ADS)

    Nur Fathiyah Jamaludin, Siti; Pubellier, Manuel; Prasad Ghosh, Deva; Menier, David; Pierson, Bernard

    2014-05-01

    Tectonics in addition to other environmental factors impacts the growth of carbonate platforms and plays an important role in shaping the internal architecture of the platforms. Detailed of faults and fractures development and healing in carbonate environment have not been explored sufficiently. Using 3D seismic and well data, we attempt to reconstruct the structural evolution of a Miocene carbonate platform in Central Luconia Province, offshore Malaysia. Luconia Province is located in the NW coast of Borneo and has become one of the largest carbonate factories in SE Asia. Seismic interpretations including seismic attribute analysis are applied to the carbonate platform to discern its sedimentology and structural details. Detailed seismic interpretations highlight the relationships of carbonate deposition with syn-depositional faulting. Branching conjugate faults are common in this carbonate platform and have become a template for reef growth, attesting lateral facies changes within the carbonate environments. Structural restoration was then appropriately performed on the interpreted seismic sections based on sequential restoration techniques, and provided images different from those of horizon flattening methods. This permits us to compensate faults' displacement, remove recent sediment layers and finally restore the older rock units prior to the fault motions. It allows prediction of platform evolution as a response to faulting before and after carbonate deposition and also enhances the pitfalls of interpretation. Once updated, the reconstructions allow unravelling of the un-seen geological features underneath the carbonate platform, such as paleo-structures and paleo-topography which in turn reflects the paleo-environment before deformations took place. Interestingly, sections balancing and restoration revealed the late-phase (Late Oligocene-Early Miocene) rifting of South China Sea, otherwise difficult to visualize on seismic sections. Later it is shown that

  9. 3D Geophysical modelling of the Karoo Basin, South Africa, to investigate basin evolution

    NASA Astrophysics Data System (ADS)

    Scheiber-Enslin, Stephanie; Ebbing, Jörg; Webb, Susan

    2014-05-01

    The Karoo Basin in South Africa has recently been identified as a possible source for shale gas. The basin which was deposited in the Late Carboniferous (300 Ma) to Middle Jurassic (180 Ma) presently covers an area of 600 000 km2. However, no clear tectonic model exists for the Karoo Basin, though several have been proposed including a retroarc foreland basin and subsidence of basement blocks combined with mantle flow. This study attempts to constrain a model using isostasy and flexure studies. In this study we present the first broad-scale 3D model of the Karoo basin based on teleseismic, reflection and refraction seismic, MT, borehole and potential field data, including satellite gravity data. The basin is shallowest in the northeast where it is underlain by the strong Archean Kaapvaal craton, and deepens over the weaker Proterozoic Namaqua-Natal mobile belt which surrounds the craton to the south and west. The basin is deepest just north of the Cape fold belt which stretches along the southern and southwestern coast of South Africa. We also present preliminary backstripping results from proximal and distal regions of the basin which reveal the extent of tectonic subsidence. The importance of including Cape syn- and post-rift sediments (~ 483 to 330 Ma) in the south in the analysis is highlighted. This allows for a complete understanding of the crustal strength at the time of Karoo deposition. Investigation of flexure profiles across the basin, from on to off-craton, show the effect of varying crustal strength during cycles of Cape orogenic loading (between 292 and 215 Ma).

  10. 3D Seismic Reflection Imaging of Crustal Formation Processes on the East Pacific Rise, 9°57-42'N

    NASA Astrophysics Data System (ADS)

    Purdy, G. M.; Mutter, J. C.; Carbotte, S. M.; Canales, J. P.; Nedimovic, M. R.; Carton, H.; Newman, K. R.; Marjanovic, M.; Xu, M.; Aghaei, O.; Stowe, L. C.

    2008-12-01

    Between June 29th and August 19th 2008 the research vessel Marcus G Langseth carried out its first multi- streamer 3D seismic reflection imaging cruise, MGL08-12, by conducting a program research on the East Pacific Rise centered around 9°50'N. The primary goals were to create an accurate 3D seismic reflection image of the magmatic-hydrothermal system at this Integrated Study Site of the Ridge2000 program by imaging the structure of the axial magma chamber (AMC) lid and oceanic crust at a resolution, accuracy, and scale comparable to seafloor observations. The vessel acquired data with four, 6-kilometer solid streamers each comprising 468 active channels deployed with a total separation of 450 meters. Four gun strings with total volume of 3300 cubic inches in two groups fired alternately provide the source for a shot spacing of 37.5 meters. This configuration yields eight CMP lines for each of the sail lines that were spaced 300 m apart, and a static bin size of 6.25 m × 37.5 m in the along-track and across-track directions, respectively, providing a nominal fold of 40. The cruise accomplished the acquisition of ~3,782 km of sail line data. There are 111 across axis lines that required 10 repeated lines and 14 infills. Average feathering during the cruise was 0° ± 5° (one standard deviation), with maximum values of up to 11°. This means that 18% of the total cross axis acquisition was needed for reshoots and infilling. A 25% multiplier on planned lines for a 3D grid is probably a useful figure to use in cruise planning and is fairly standard in the seismic industry. Data quality meets or exceeds industry standards. 3D coverage was achieved in two areas. The larger comprises a set of 93 equally spaced lines forming the 3D grid between 9°57'N and 9°42'N. This grid is made up of lines from all of racetracks #1 and #2 and the northern lines of racetrack#3 and covers two principal hydrothermal vent areas in a continuous fashion. The second 3D area is comprised

  11. Assessing the quality of earthquake source models using 3-D forward modelling of long-period seismic data

    NASA Astrophysics Data System (ADS)

    Ferreira, A. M.; Vallée, M.; Lentas, K.

    2010-12-01

    Accurate earthquake point source parameters (e.g. seismic moment, depth and focal mechanism) provide key first-order information for detailed studies of the earthquake source process and for improved seismic and tsunami hazard evaluation. In order to objectively assess the quality of seismic source models, it is important to go beyond classical resolution/misfit checks. In particular, it is desirable to apply sophisticated modeling techniques to quantify uncertainties due to simplified theoretical formulations and/or Earth structure employed to build the source models. Moreover, it is important to verify how well the models explain data not used in their construction for a complete, quantitative assessment of the earthquake source models. In this study we compare the quality of the surface-wave Centroid Moment Tensor (CMT) method with that of the SCARDEC method, which is a new automated body-wave technique for the fast simultaneous determination of the seismic moment, focal mechanism, depth and source time functions of large earthquakes. We focus on the major shallow subduction earthquakes of the last 20 years, for which there are some systematic differences between SCARDEC and CMT source parameters, notably in fault dip angle and moment magnitude. Because the SCARDEC method is based on body-wave deconvolution using ray methods in a 1D Earth model, we test how well SCARDEC source parameters explain long-period seismic data (surface waves and normal modes) compared to the CMT method. We calculate theoretical seismograms using two forward modelling techniques (full ray theory and spectral element method) to simulate the long-period seismic wavefield for the 3D Earth model S20RTS combined with the crust model CRUST2.0, and for two point source models: (i) the SCARDEC model; and (ii) the Global CMT model. We compare the synthetic seismograms with real broadband data from the FDSN for the major subduction earthquakes of the last 20 years. We show that SCARDEC source

  12. Fusion of terrestrial LiDAR and tomographic mapping data for 3D karst landform investigation

    NASA Astrophysics Data System (ADS)

    Höfle, B.; Forbriger, M.; Siart, C.; Nowaczinski, E.

    2012-04-01

    Highly detailed topographic information has gained in importance for studying Earth surface landforms and processes. LiDAR has evolved into the state-of-the-art technology for 3D data acquisition on various scales. This multi-sensor system can be operated on several platforms such as airborne LS (ALS), mobile LS (MLS) from moving vehicles or stationary on ground (terrestrial LS, TLS). In karst research the integral investigation of surface and subsurface components of solution depressions (e.g. sediment-filled dolines) is required to gather and quantify the linked geomorphic processes such as sediment flux and limestone dissolution. To acquire the depth of the different subsurface layers, a combination of seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) is increasingly applied. This multi-method approach allows modeling the extension of different subsurface media (i.e. colluvial fill, epikarst zone and underlying basal bedrock). Subsequent fusion of the complementary techniques - LiDAR surface and tomographic subsurface data - first-time enables 3D prospection and visualization as well as quantification of geomorphometric parameters (e.g. depth, volume, slope and aspect). This study introduces a novel GIS-based method for semi-automated fusion of TLS and geophysical data. The study area is located in the Dikti Mountains of East Crete and covers two adjacent dolines. The TLS data was acquired with a Riegl VZ-400 scanner from 12 scan positions located mainly at the doline divide. The scan positions were co-registered using the iterative closest point (ICP) algorithm of RiSCAN PRO. For the digital elevation rasters a resolution of 0.5 m was defined. The digital surface model (DSM) of the study was derived by moving plane interpolation of all laser points (including objects) using the OPALS software. The digital terrain model (DTM) was generated by iteratively "eroding" objects in the DSM by minimum filter, which additionally accounts for

  13. Cognitive 3D geological voxel modelling based on AEM and seismic data - a case from the southern part of Denmark

    NASA Astrophysics Data System (ADS)

    Jørgensen, Flemming; Møller, Rasmus R.; Sandersen, Peter B. E.; Høyer, Anne-Sophie

    2013-04-01

    The highly complex composition of the Quaternary and Tertiary near-surface deposits in Denmark is a challenging environment for 3D modelling. Geological elements like cross-cutting buried valleys, faults, glaciotectonic thrusts and folds, delta units and erosional unconformities are vital to identify and include in 3D geological models, but at the same time they all add to the complexity of the geological picture. Borehole data are rarely sufficient for the modelling; instead much more laterally dense data are needed. Airborne electromagnetic techniques therefore serve as perfect tools for providing an overview and spatial distribution of the geological elements and their composition. Such airborne surveys are perfectly supplemented by seismic data in order to map the stratigraphic framework within a model area. Translating airborne electromagnetic data to geology is a complicated task that requires a significant amount of geophysical and geological insight. It is necessary to implement thorough geological background knowledge in the interpretations while at the same time identify and acknowledge the inherent limitations of the method. In an area covering 730 km2 across the border between Germany and Denmark a combination of an airborne transient electromagnetic survey (3200 line km performed with the SkyTEM system) and a 38 km high-resolution 2D seismic survey has proven very successful for mapping geological elements like the above-mentioned. Although the south-westernmost part of the study area is saturated with saltwater and the TEM data therefore are influenced by increased electrical conductivity, the geology is still revealed here. Geological interpretations are supported by a high number of pre-existing seismic sections originating from hydrocarbon exploration and borehole data, though most of the borehole data and several of the seismic sections have very poor quality. A couple of new 300-m deep exploration boreholes have been drilled in order to obtain

  14. 3-D geodynamic models of the India-Eurasia collision zone: Guiding numerical models with seismic and MT observations

    NASA Astrophysics Data System (ADS)

    Bischoff, S. H.; Flesch, L. M.

    2015-12-01

    Piecing together the uplift and growth of the Tibetan Plateau requires a robust understanding of the present-day dynamics of the India-Eurasia collision zone. To aid in the understanding of mountain building and plateau growth, we developed a 3D finite element model of the Tibetan Plateau following Flesch and Bendick (2012). Our model is based on the vast collection of published geophysical data and employs COMSOL Multiphysics (www.comsol.com). We assume model material properties from the wide variety of published seismic and MT studies, incorporated with an updated, vertically averaged, effective viscosity distribution from Flesch et al. (2001). We test potential relationships between conductance/seismic velocity and strength (viscosity) by modeling strength difference contacts at imaged interfaces. We quantify fitness of candidate 3D viscosity functions by comparing solved model surface velocities to observed surface velocities inferred from GPS and Quaternary fault slip rates. The model geometry incorporates Earth curvature and extends eastward from 65° to 110°E, northward from 15° to 45°N, and vertically down to 100 km below sea level. The physics of deformation is governed by the Stokes equations describing incompressible Newtonian fluid flow. Boundary conditions consist of free slip across the bottom surface (representing the lithosphere-asthenosphere boundary) and moving edge walls constrained by a GPS-derived, continuous velocity field. Model results indicate a tradeoff between crust and mantle dominant strength. Best-fit models are achieved by a combination of strong crust/upper mantle with additional strain accommodation in localized weak zones.

  15. Crustal high-velocity anomaly at the East European Craton margin in SE Poland (TESZ) modelled by 3-D seismic tomography of refracted and reflected arrivals

    NASA Astrophysics Data System (ADS)

    Środa, Piotr; Dec, Monika

    2016-04-01

    The area of Trans-European Suture Zone in SE Poland represents a contact of major tectonic units of different consolidation age - from the Precambrian East European Craton, through Palaeozoic West European Platform to Cenozoic Carpathian orogen. The region was built by several phases of crustal accretion, which resulted in a complex collage of tectonic blocks. In 2000, this region was studied by several seismic wide-angle profiles of CELEBRATION 2000 experiment, providing a dense coverage of seismic data in SE Poland and allowing for detailed investigations of the crustal structure and properties in this area. Beneath the marginal part of the EEC, the 2-D modelling of in-line data form several CELEBRATION profiles revealed a prominent high P-wave velocity anomaly in the upper crust, with Vp of 6.7-7.1 km/s, starting at 10-16 km depth (e.g., Środa et al., 2006). Anomalously high velocities are observed in the area located approximately beneath Lublin trough, to the NE of Teisseyre-Tornquist Zone. Based on 3-D tomography of first arrivals of in- and off-line CELEBRATION 2000 recordings (Malinowski et al., 2008), elevated velocities are also reported in the same area and seem to continue to the SW, off the craton margin. Gravimetric modelling also revealed anomalously high density in the same region at similar depths. High seismic velocities and densities are interpreted as indicative for a pronounced mafic intrusion, possibly related to extensional processes at the EEC margin. Previous 3-D models of the high-velocity intrusion were based on first arrivals (crustal refractions) only. In this study, also off-line reflections (not modelled up to now) are used, in order to enlarge the data set and to better constrain the geometry and properties of the velocity anomaly. A code for 3-D joint tomographic inversion of refracted and reflected arrivals, with model parametrization allowing for velocity discontinuities was used (Rawlinson, 2007). With this approach, besides the

  16. Very-high-resolution pseudo 3-D seismic volume of a submarine mass movement deposit: an example from the Pointe-du-Fort area, Upper Saguenay Fjord, Canada.

    NASA Astrophysics Data System (ADS)

    Duchesne, M. J.; Hart, B.; Riedel, M.

    2003-04-01

    In the last few years, 3-D seismic has grown beyond the petroleum geology field in a variety of domains such as environmental and mining geology. However, very-high-resolution 3-D seismic volumes have not yet been used extensively in marine geology to reconstitute the evolution in space of a submarine landslide. The Upper Saguenay Fjord region has been recently struck, by various natural disasters including earthquakes, landslides and flash floods. This region represents a unique site to study the internal structure of modern mass wasting deposits. The Pointe-du-Fort mass movement deposits were chosen to adapt and apply 3-D seismic technology utilized in the petroleum industry. Its small size has helped to overcome the scale characterization problems often encountered within the study of larger submarine slides. Some authors have proposed that these deposits represent the spread of a failed mass coming from the south fjord wall triggered by an earthquake. A very-high resolution pseudo 3-D seismic volume was produced to provide a better understanding of the Pointe-du-Fort failed mass. The volume was generated by merging 38 closely spaced 2-D single channel seismic profiles and has permitted to image the internal structure of the mass movement deposits. The seismic data reveal surfaces within the failure lobe that divide it up into smaller units. These observations are consistent with either: a) the stacking of multiple debris flows rather than a single spread event, or b) internal deformation/shear within a failing mass.

  17. Seismic fabric and 3-D structure of the southwestern intracontinental Palmyride fold belt, Syria

    SciTech Connect

    Chaimov, T.A.; Barazangi, M. ); Al-Saad, D.; Sawaf, T.; Khaddour, M. )

    1993-12-01

    The Palmyride fold belt, a 400 x 100 km transpressive belt in central Syria that is the northeastern arm of the Syrian arc, is the result of late Mesozoic and Cenozoic inversion of a late Paleozoic and Mesozoic, northeast-trending, linear intracontinental basin located within the northern Arabian platform. The southwestern Palmyrides, near the Dead Sea transform fault system and the Anti-Lebanon mountains, are characterized by short wavelength (5--10 km) en echelon folds separated by small intermontane basins that developed mainly in the Neogene to Holocene. A new three-dimensional data cube, 60 x 70 x 10 km, generated on a Landmark Graphics workstation and based on approximately 700 km of two-dimensional seismic reflection profiles, elucidates the structure of the upper 10 km of the crust in the southwestern Palmyrides. Visualization of the subsurface structure, which is represented by a prominent Upper Cretaceous reflection surface in the data cube, is augmented by topographical and Bouguer gravity data of the same region. Preexisting discontinuities, probable normal fault relicts of the Mesozoic Palmyride rift, likely controlled the development of individual Neogene thrusts. The new subsurface image shows important structural features not identified in outcrop. Short, west-northwest-trending transcurrent (or transfer) faults like the short, en echelon northeast-trending thrust faults and blind thrusts of the Palmyrides. A pervasive regional decollment is not observed, even though Triassic evaporites host local detachments. Unlike topographic relief, which only roughly resembles subsurface structures, the Bouguer gravity signature of the southwestern Palmyrides closely mimics underlying shallow geologic structures both on a large ([approximately]50 km wavelength) and a small ([approximately]5--10 km wavelength) scale. The structural analysis and many other recent studies of the region indicate minor right-lateral shear coupled with compression in the Palmyrides.

  18. Beyond the Seafloor: a Plio-Pleistocene Archive of Glacial Geomorphology from Basin-Wide 3D Seismic Reflection Data on the Mid-Norwegian Shelf

    NASA Astrophysics Data System (ADS)

    Newton, A.; Huuse, M.

    2015-12-01

    Oil and gas exploration on the mid-Norwegian shelf has created an extensive geophysical and geological database. As such, this margin has become one of the most comprehensively studied formerly-glaciated continental margins in the world. Industrial operations have concentrated on the structure and geohazard potential of glacial sediments whilst academic work has looked at reconstructing environmental conditions during and since the Last Glacial Maximum (LGM). This has generally consisted of mapping seafloor glacial geomorphology and a limited number of shallow sediment cores. Despite the increasingly large volume of 3D seismic reflection data available across the majority of the shelf, only limited work has been carried out investigating the oldest glaciations. A Plio-Pleistocene archive of glacial-interglacial history is preserved offshore and represents a unique study site because of the availability of 100s of 3D seismic reflection datasets. This database allows numerous different glacial erosion events and glacial landforms to be imaged throughout the glacially-derived NAUST Formation. We present an inventory of glacial history for the mid-Norwegian shelf and review the implications for the glacial history of Northwest Europe. This record shows glacial landforms such as iceberg scours, mega-scale glacial lineations and grounding-zone wedges, each of which provides an insight into ice characteristics. Dating is limited to a few tentative dates based on side-wall core data but we infer a further dating chronology based on dated sediments from the Voring Plateau, fluctuations in the benthic δ18O derived global sea level record, interpretation of seismic facies and the overall architecture. Glacial evidence is present regularly throughout the stratigraphy with the earliest evidence for marine terminating ice found at the base of the NAUST Formation at ~2.8 Ma.

  19. Upper Crustal Structure above Off-axis Magma Lenses at RIDGE-2000 East Pacific Rise Integrated Study Site from 3D Multichannel Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Han, S.; Carbotte, S. M.; Carton, H. D.; Newman, K. R.; Canales, J.; Nedimovic, M. R.

    2010-12-01

    The 2008 multi-streamer 3D seismic reflection experiment conducted aboard the R/V Marcus Langseth at the RIDGE-2000 East Pacific Rise Integrated Study Site reveals prominent near-axis crustal reflectors on both the east and west flanks of the ridge crest which are interpreted as off-axis melt lenses (OAML) injected at mid-crustal levels. These OAML are probable sites of off-axis volcanism and provide potential heat sources for localized hydrothermal circulation on the ridge flanks, which we speculate may affect off-axis upper crustal structure. To investigate the effect of OAML on the upper crustal structure, we choose two across-axis lines above a prominent OAML on the east flank of the ridge that is present in the southernmost part of our study area: Line 1428P across the middle part of the OAML near 9° 38’N and Line 1476P across the northern end of this OAML near 9° 39’N. Initial analysis includes 2D processing to produce seismic reflection images for each line and 1D travel time modeling on CMP super gathers to characterize Layer 2A and upper Layer 2B velocity structure. Comparison of seismic reflection images and upper crustal velocity structure for the two lines shows a decrease in Layer 2A thickness by 150m and a decrease in the uppermost 2B velocity by 10-20% above the central portion of OAML. We attribute these local anomalies to alteration associated with off-axis hydrothermal circulation driven by the OAML where enhanced precipitation of alteration minerals may seal porosity within lowermost Layer 2A, converting it to lower velocity uppermost Layer 2B. To further constrain the velocity structure of Layer 2A and Layer 2B, we conduct 2D P-wave tomography with downward continued shot gathers along the studied lines (Harding et al, 2007). The downward continued shot gathers simulate seismic sources and receivers located near the seafloor, and therefore provide travel time information from near-offset refractions that are normally obscured by the

  20. Investigation of out of plane compressive strength of 3D printed sandwich composites

    NASA Astrophysics Data System (ADS)

    Dikshit, V.; Yap, Y. L.; Goh, G. D.; Yang, H.; Lim, J. C.; Qi, X.; Yeong, W. Y.; Wei, J.

    2016-07-01

    In this study, the 3D printing technique was utilized to manufacture the sandwich composites. Composite filament fabrication based 3D printer was used to print the face-sheet, and inkjet 3D printer was used to print the sandwich core structure. This work aims to study the compressive failure of the sandwich structure manufactured by using these two manufacturing techniques. Two different types of core structures were investigated with the same type of face-sheet configuration. The core structures were printed using photopolymer, while the face-sheet was made using nylon/glass. The out-of-plane compressive strength of the 3D printed sandwich composite structure has been examined in accordance with ASTM standards C365/C365-M and presented in this paper.

  1. Seismic investigations - The Viking Mars Lander.

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Kovach, R. L.; Latham, G.; Press, F.; Nafi Toksoz, M.; Sutton, G.

    1972-01-01

    A lightweight three-component short period seismometer has been developed for preliminary seismic investigations of Mars. Because of weight and data-rate constraints the Viking seismic experiment is far from optimal but it should, at a minimum, provide information about the microseismic level and an upper bound on the seismicity of the planet. If Mars is tectonically active a start can be made on the problem of the internal structure, dynamics, and composition of the planet. A good distribution of modest sized Marsquakes will make it possible to determine if Mars has a core. The size of the core is related to the conditions of planetary formation.

  2. 3-D Tomography Study of Seismic Refraction/Wide-Angle Reflection Data Across the Variscides, SW Ireland

    NASA Astrophysics Data System (ADS)

    O'Reilly, B. M.; Landes, M.; Readman, P. W.; Shannon, P. M.; Prodehl, C.

    2002-12-01

    The VARNET-96 seismic experiment acquired three seismic refraction/wide-angle reflection profiles in order to examine the crustal structure in the south-west of Ireland. 170 seismic stations were used on 300 recording sites. The shotpoint geometry was designed to allow for both in-line and off-line fan shot recordings on the three profiles. A total of 34 water shots was fired. Results from 3-D raytrace and inversion modelling illustrate the pervasive lateral heterogeneity of the study area south of the Shannon Estuary. Palaeozoic strata at the south coast are about 5-6 km thick associated with the sedimentary infill of the Munster and South Munster Basins. To the north, shallow upper crust in the vicinity of the Killarney-Mallow Fault Zone is followed by a 3-4 km thick sedimentary succession in the Dingle-Shannon Basin. A zone of high-velocity upper crust (6.4-6.6 km/s) beneath the South Munster Basin correlates with a gravity high between the Kenmare-Killarney and the Leinster Granite gravity lows. Other high-velocity zones were found beneath Dingle Bay and the Kenmare River region and may be associated with the deep traces of the Killarney-Mallow Fault Zone and the Cork-Kenmare Line. The 3-D velocity model was taken as a basis for the computation of PmP reflected arrivals from the crust-mantle boundary. The Moho depth varies from about 28-29 km at the south coast to about 32-33 km beneath the Dingle-Shannon Basin, the region where the 2-D inline model shows a south-dipping reflector in the upper mantle. Pervasive Variscan deformation appears to be confined to the sedimentary and upper crustal structure and has not deformed the entire crust supporting a thin-skinned tectonic model for Variscan deformation. Deep-crustal variations only occur where they can be correlated with major tectonic features such as the Caledonian Iapetus Suture near the Shannon Estuary. The shallowing of the Moho towards the coast may result from Mesozoic crustal extension in the adjacent

  3. Method for identifying subsurface fluid migration and drainage pathways in and among oil and gas reservoirs using 3-D and 4-D seismic imaging

    DOEpatents

    Anderson, R.N.; Boulanger, A.; Bagdonas, E.P.; Xu, L.; He, W.

    1996-12-17

    The invention utilizes 3-D and 4-D seismic surveys as a means of deriving information useful in petroleum exploration and reservoir management. The methods use both single seismic surveys (3-D) and multiple seismic surveys separated in time (4-D) of a region of interest to determine large scale migration pathways within sedimentary basins, and fine scale drainage structure and oil-water-gas regions within individual petroleum producing reservoirs. Such structure is identified using pattern recognition tools which define the regions of interest. The 4-D seismic data sets may be used for data completion for large scale structure where time intervals between surveys do not allow for dynamic evolution. The 4-D seismic data sets also may be used to find variations over time of small scale structure within individual reservoirs which may be used to identify petroleum drainage pathways, oil-water-gas regions and, hence, attractive drilling targets. After spatial orientation, and amplitude and frequency matching of the multiple seismic data sets, High Amplitude Event (HAE) regions consistent with the presence of petroleum are identified using seismic attribute analysis. High Amplitude Regions are grown and interconnected to establish plumbing networks on the large scale and reservoir structure on the small scale. Small scale variations over time between seismic surveys within individual reservoirs are identified and used to identify drainage patterns and bypassed petroleum to be recovered. The location of such drainage patterns and bypassed petroleum may be used to site wells. 22 figs.

  4. Method for identifying subsurface fluid migration and drainage pathways in and among oil and gas reservoirs using 3-D and 4-D seismic imaging

    DOEpatents

    Anderson, Roger N.; Boulanger, Albert; Bagdonas, Edward P.; Xu, Liqing; He, Wei

    1996-01-01

    The invention utilizes 3-D and 4-D seismic surveys as a means of deriving information useful in petroleum exploration and reservoir management. The methods use both single seismic surveys (3-D) and multiple seismic surveys separated in time (4-D) of a region of interest to determine large scale migration pathways within sedimentary basins, and fine scale drainage structure and oil-water-gas regions within individual petroleum producing reservoirs. Such structure is identified using pattern recognition tools which define the regions of interest. The 4-D seismic data sets may be used for data completion for large scale structure where time intervals between surveys do not allow for dynamic evolution. The 4-D seismic data sets also may be used to find variations over time of small scale structure within individual reservoirs which may be used to identify petroleum drainage pathways, oil-water-gas regions and, hence, attractive drilling targets. After spatial orientation, and amplitude and frequency matching of the multiple seismic data sets, High Amplitude Event (HAE) regions consistent with the presence of petroleum are identified using seismic attribute analysis. High Amplitude Regions are grown and interconnected to establish plumbing networks on the large scale and reservoir structure on the small scale. Small scale variations over time between seismic surveys within individual reservoirs are identified and used to identify drainage patterns and bypassed petroleum to be recovered. The location of such drainage patterns and bypassed petroleum may be used to site wells.

  5. 3D simultaneous refraction and reflection seismic tomography based on SIMUL with applications to the TRANSALP wide-angle data

    NASA Astrophysics Data System (ADS)

    Bleibinhaus, F.; Gebrande, H.

    2003-04-01

    Applications of seismic travel time tomography are restricted for the most part either to the direct wave or to 2D. Based on the SIMULPS13Q version (Rietbrock, 1996) of the wide-spread SIMUL-code-family and the concepts of flexible gridding (Thurber, 1983-1999) we developed a simultaneous 3D inversion for slowness and reflector depth. The tomographic algorithm is based on an irregular model parametrization adjusted to the resolving power of the data and a damped LSQR matrix inversion. In a first step accuracy of the forward modeling has been improved, in particular for large recording distances, crucial for the inversion of PMP or Pn observations. In a second step the modelling of reflectors and reflections has been integrated and the simultaneous inversion has been extended to reflector depth nodes. Reflectors are modelled by bi-cubic splines and can be "floating", i.e. without impact on the velocities, or discontinuous. A wide variety of geological situations can be parameterized, from layered structures to almost vertical faults. The method has been applied to the TRANSALP refraction seismic data recorded in the Eastern Alps in 1998/99 (TRANSALP Working Group, 2001). The data consists of vibro- and explosion seismic signals recorded by 30 to 110 three-component stations distributed along a 220 km long segment of the profile. Vibroseis signals were observed in up to 80 km distance. Different 1D and 2D starting models converge to very similar results. We obtained a high resolution model of the upper crust with 2.5 kms horizontal grid spacing which has been used for migration of the near-vertical data. Resolution degrades significantly in greater depths. The inverted Moho is consistent with other results (TRANSALP Working Group, 2002). Rietbrock, A., 1996. Entwicklung eines Programmsystems zur konsistenten Auswertung grosser seismologischer Datensaetze mit Anwendung auf die Untersuchung der Absorptionsstruktur der Loma-Prieta-Region, Kalifornien. Ph

  6. Land 3D-seismic data: Preprocessing quality control utilizing survey design specifications, noise properties, normal moveout, first breaks, and offset

    USGS Publications Warehouse

    Raef, A.

    2009-01-01

    The recent proliferation of the 3D reflection seismic method into the near-surface area of geophysical applications, especially in response to the emergence of the need to comprehensively characterize and monitor near-surface carbon dioxide sequestration in shallow saline aquifers around the world, justifies the emphasis on cost-effective and robust quality control and assurance (QC/QA) workflow of 3D seismic data preprocessing that is suitable for near-surface applications. The main purpose of our seismic data preprocessing QC is to enable the use of appropriate header information, data that are free of noise-dominated traces, and/or flawed vertical stacking in subsequent processing steps. In this article, I provide an account of utilizing survey design specifications, noise properties, first breaks, and normal moveout for rapid and thorough graphical QC/QA diagnostics, which are easy to apply and efficient in the diagnosis of inconsistencies. A correlated vibroseis time-lapse 3D-seismic data set from a CO2-flood monitoring survey is used for demonstrating QC diagnostics. An important by-product of the QC workflow is establishing the number of layers for a refraction statics model in a data-driven graphical manner that capitalizes on the spatial coverage of the 3D seismic data. ?? China University of Geosciences (Wuhan) and Springer-Verlag GmbH 2009.

  7. BM platform, B Field, Offshore Northwest Java: A case history of multi-disciplinary integration including 3D seismic, reservoir simulation and horizontal drilling

    SciTech Connect

    Cooke, D.; Aziz, A.; Baldauff, J.; Diswarin, N.

    1996-12-31

    This case history describes how a multidisciplinary team used a 3D survey and reservoir simulation to review and revise the development plans for the BM platform, located in the B Field, Offshore Northwest Java, Indonesia. The case history starts with the collection of necessary parophysical, geologic and production data. These data are input to a reservoir simulation which shows there should be no problems with the new platform. However, this initial simulation has known problems with contradicting input structure maps and fluid contacts. Hopefully, these problems can be addressed with a new 3D seismic survey - if the seismic data can be acquired, processed, interpreted and input to the simulation before drilling starts at the BM platform. The seismic acquisition could not be done with the traditional towed seismic streamer cables - instead stationary ocean bottom cables with dual geophone-hydrophone sensors were used. Processing of the seismic data was done in a way that allowed interpretation of the critical area even before acquisition of the entire survey was finished. The new 3D structure maps changed the MDT`s opinion of what reservoir and what areas contained the bulk of the oil reserves. Unfortunately, the new maps were not available until after the jacket was set but before the wells drilled. The NMT updated the simulation with the new 3D data, which led to changes in development well bottom hole locations and an ambitious horizontal well.

  8. Seismic and structural characterization of the fluid bypass system using 3D and partial stack seismic from passive margin: inside the plumbing system.

    NASA Astrophysics Data System (ADS)

    Iacopini, David; Maestrelli, Daniele; Jihad, Ali; Bond, Clare; Bonini, Marco

    2017-04-01

    In recent years enormous attention has been paid to the understanding of the process and mechanism controlling the gas seepage and more generally the fluid expulsion affecting the earth system from onshore to offshore environment. This is because of their demonstrated impact to our environment, climate change and during subsea drilling operation. Several example from active and paleo system has been so far characterized and proposed using subsurface exploration, geophysical and geochemical monitoring technology approaches with the aims to explore what trigger and drive the overpressure necessary maintain the fluid/gas/material expulsion and what are the structure that act as a gateway for gaseous fluid and unconsolidated rock. In this contribution we explore a series of fluid escape structure (ranging from seepage pipes to large blowout pipes structure of km length) using 3D and partial stack seismic data from two distinctive passive margin from the north sea (Loyal field, West Shetland) and the Equatorial Brazil (Ceara' Basin). We will focuses on the characterization of the plumbing system internal architecture and, for selected example, exploring the AVO response (using partial stack) of the internal fluid/unconsolidated rock. The detailed seismic mapping and seismic attributes analysis of the conduit system helped us to recover some detail from the signal response of the chimney internal structures. We observed: (1) small to medium seeps and pipes following structural or sedimentary discontinuities (2) large pipes (probably incipient mud volcanoes) and blowup structures propagating upward irrespective of pre-existing fault by hydraulic fracturing and assisted by the buoyancy of a fluidised and mobilised mud-hydrocarbon mixture. The reflector termination observed inside the main conduits, the distribution of stacked bright reflectors and the AVO analysis suggests an evolution of mechanisms (involving mixture of gas, fluid and probably mud) during pipe birth and

  9. Numerical Investigation of 3D multichannel analysis of surface wave method

    NASA Astrophysics Data System (ADS)

    Wang, Limin; Xu, Yixian; Luo, Yinhe

    2015-08-01

    Multichannel analysis of surface wave (MASW) method is an efficient tool to obtain near-surface S-wave velocity, and it has gained popularity in engineering practice. Up to now, most examples of using the MASW technique are focused on 2D models or data from a 1D linear receiver spread. We propose a 3D MASW scheme. A finite-difference (FD) method is used to investigate the method using linear and fan-shaped receiver spreads. Results show that the 3D topography strongly affects propagation of Rayleigh waves. The energy concentration of dispersion image is distorted and bifurcated because of the influence of free-surface topography. These effects are reduced with the 3D MASW method. Lastly we investigate the relation between the array size and the resolution of dispersion measurement.

  10. Quasi 3D Geoelectrical Imaging as a new application for permafrost investigations: Some methodological aspects

    NASA Astrophysics Data System (ADS)

    Bast, A.; Kneisel, C.

    2009-04-01

    The two-dimensional electrical resistivity tomography (ERT) application is a common tool to investigate periglacial environments and has evolved rapidly over the last years. The method has been often applied with great success in mountainous systems even though they are characterized by a complex heterogeonous and rough terrain. Despite the development of advanced instrumentation and commercial three-dimensional processing software, in general the two-dimensional approach is used. True three-dimensional measurements in high mountain environments are difficult to realize due to the rough and complex domain. However, up to now, an efficient three-dimensional geophysical mapping of the subsurface characteristics and lithology in alpine environments has not been possible. An auspicious approach is to sound the subsurface with two-dimensional measurements, each of them is routinely being interpreted with commercial software packages and then the results are merged to generate a quasi or pseudo three-dimensional geoelectrical image of the subsurface. Our study presents first results of two quasi 3D geoelectrical images, located in the Val Muragl glacier forefield, Upper Engadin, Swiss Alps. The site of the first model is in the lower part of the forefield the second in the upper part. They distinguish between the surface material: While the lower part is characterized by coarse blocky but although finer grained surface material, the upper site consists of much more finer grained substrate. At both sites a permanently geoelectrical monitoring survey-line is installed, as well as a borehole, which was drilled in summer of 2006 and extent to a depth of 8m below ground surface. Furthermore, miniature temperature logger, BTS (bottom temperature of snow cover) and seismic refraction data are available for the glacier forefield. Data acquisition has been undertaken with a multi-electrode Iris Syscal Junior Switch equipment, data processing with different commercial software

  11. Volume estimation of rift-related magmatic features using seismic interpretation and 3D inversion of gravity data on the Guinea Plateau, West Africa

    NASA Astrophysics Data System (ADS)

    Kardell, Dominik A.

    The two end-member concept of mantle plume-driven versus far field stress-driven continental rifting anticipates high volumes of magma emplaced close to the rift-initiating plume, whereas relatively low magmatic volumes are predicted at large distances from the plume where the rifting is thought to be driven by far field stresses. We test this concept at the Guinea Plateau, which represents the last area of separation between Africa and South America, by investigating for rift-related volumes of magmatism using borehole, 3D seismic, and gravity data to run structural 3D inversions in two different data areas. Despite our interpretation of igneous rocks spanning large areas of continental shelf covered by the available seismic surveys, the calculated volumes in the Guinea Plateau barely match the magmatic volumes of other magma-poor margins and thus endorse the aforementioned concept. While the volcanic units on the shelf seem to be characterized more dominantly by horizontally deposited extrusive volcanic flows distributed over larger areas, numerous paleo-seamounts pierce complexly deformed pre and syn-rift sedimentary units on the slope. As non-uniqueness is an omnipresent issue when using potential field data to model geologic features, our method faced some challenges in the areas exhibiting complicated geology. In this situation less rigid constraints were applied in the modeling process. The misfit issues were successfully addressed by filtering the frequency content of the gravity data according to the depth of the investigated geology. In this work, we classify and compare our volume estimates for rift-related magmatism between the Guinea Fracture Zone (FZ) and the Saint Paul's FZ while presenting the refinements applied to our modeling technique.

  12. Quantitative 3D investigation of Neuronal network in mouse spinal cord model

    NASA Astrophysics Data System (ADS)

    Bukreeva, I.; Campi, G.; Fratini, M.; Spanò, R.; Bucci, D.; Battaglia, G.; Giove, F.; Bravin, A.; Uccelli, A.; Venturi, C.; Mastrogiacomo, M.; Cedola, A.

    2017-01-01

    The investigation of the neuronal network in mouse spinal cord models represents the basis for the research on neurodegenerative diseases. In this framework, the quantitative analysis of the single elements in different districts is a crucial task. However, conventional 3D imaging techniques do not have enough spatial resolution and contrast to allow for a quantitative investigation of the neuronal network. Exploiting the high coherence and the high flux of synchrotron sources, X-ray Phase-Contrast multiscale-Tomography allows for the 3D investigation of the neuronal microanatomy without any aggressive sample preparation or sectioning. We investigated healthy-mouse neuronal architecture by imaging the 3D distribution of the neuronal-network with a spatial resolution of 640 nm. The high quality of the obtained images enables a quantitative study of the neuronal structure on a subject-by-subject basis. We developed and applied a spatial statistical analysis on the motor neurons to obtain quantitative information on their 3D arrangement in the healthy-mice spinal cord. Then, we compared the obtained results with a mouse model of multiple sclerosis. Our approach paves the way to the creation of a “database” for the characterization of the neuronal network main features for a comparative investigation of neurodegenerative diseases and therapies.

  13. Quantitative 3D investigation of Neuronal network in mouse spinal cord model

    PubMed Central

    Bukreeva, I.; Campi, G.; Fratini, M.; Spanò, R.; Bucci, D.; Battaglia, G.; Giove, F.; Bravin, A.; Uccelli, A.; Venturi, C.; Mastrogiacomo, M.; Cedola, A.

    2017-01-01

    The investigation of the neuronal network in mouse spinal cord models represents the basis for the research on neurodegenerative diseases. In this framework, the quantitative analysis of the single elements in different districts is a crucial task. However, conventional 3D imaging techniques do not have enough spatial resolution and contrast to allow for a quantitative investigation of the neuronal network. Exploiting the high coherence and the high flux of synchrotron sources, X-ray Phase-Contrast multiscale-Tomography allows for the 3D investigation of the neuronal microanatomy without any aggressive sample preparation or sectioning. We investigated healthy-mouse neuronal architecture by imaging the 3D distribution of the neuronal-network with a spatial resolution of 640 nm. The high quality of the obtained images enables a quantitative study of the neuronal structure on a subject-by-subject basis. We developed and applied a spatial statistical analysis on the motor neurons to obtain quantitative information on their 3D arrangement in the healthy-mice spinal cord. Then, we compared the obtained results with a mouse model of multiple sclerosis. Our approach paves the way to the creation of a “database” for the characterization of the neuronal network main features for a comparative investigation of neurodegenerative diseases and therapies. PMID:28112212

  14. Quantitative 3D investigation of Neuronal network in mouse spinal cord model.

    PubMed

    Bukreeva, I; Campi, G; Fratini, M; Spanò, R; Bucci, D; Battaglia, G; Giove, F; Bravin, A; Uccelli, A; Venturi, C; Mastrogiacomo, M; Cedola, A

    2017-01-23

    The investigation of the neuronal network in mouse spinal cord models represents the basis for the research on neurodegenerative diseases. In this framework, the quantitative analysis of the single elements in different districts is a crucial task. However, conventional 3D imaging techniques do not have enough spatial resolution and contrast to allow for a quantitative investigation of the neuronal network. Exploiting the high coherence and the high flux of synchrotron sources, X-ray Phase-Contrast multiscale-Tomography allows for the 3D investigation of the neuronal microanatomy without any aggressive sample preparation or sectioning. We investigated healthy-mouse neuronal architecture by imaging the 3D distribution of the neuronal-network with a spatial resolution of 640 nm. The high quality of the obtained images enables a quantitative study of the neuronal structure on a subject-by-subject basis. We developed and applied a spatial statistical analysis on the motor neurons to obtain quantitative information on their 3D arrangement in the healthy-mice spinal cord. Then, we compared the obtained results with a mouse model of multiple sclerosis. Our approach paves the way to the creation of a "database" for the characterization of the neuronal network main features for a comparative investigation of neurodegenerative diseases and therapies.

  15. Seismic reflection profiling employed in the 3D-modeling of mineralized regions: A case study from Pyhäsalmi VHMS-deposit, Finland

    NASA Astrophysics Data System (ADS)

    Heinonen, S.; Snyder, D. B.; Heikkinen, P. J.; Kukkonen, I. T.

    2012-04-01

    Structures of the upper crust can be best understood by using 3D visualization and modeling techniques. Often most of the geological data available for such studies are from the surface and geophysical methods are needed to follow the features mapped from the surface to the depth. The seismic reflection profiling, or 3D-seismic studies, provide an important tool for geophysical-geological modeling. We present the results of the on-going 3D-modeling from Pyhäsalmi, Finland. In this study, six seismic profiles acquired in the area during project HIRE (High Resolution Reflection Seismics for Ore Exploration, 2007-2010) are used to develop and constrain the geological 3D-modeling.The Pyhäsalmi volcanic hosted massive sulfide (VHMS) deposit (>50 Mt) is located in a Proterozoic volcanic belt in central Finland. Currently mine is ~1.5km deep. The existing infrastructure with depth enables the economic exploitation of new deep ore reserves giving motivation for the geological modeling. Drill hole logging indicates that the seismic imaging of contacts between mafic and felsic volcanic rocks is plausible. Furthermore, acoustic impedance of Pyhäsalmi ore (32 x 106 kg/m2s) is distinct from the host rocks (16-19 x 106 kg/m2s) enabling its detection with seismic reflection methods. Six seismic profiles show discontinuous reflectors and complicated reflectivity patterns due to the complex geology. We used the texture and intensity of reflectivity together with individual reflectors and drill hole data to model the geological structures of the area. Near the surface (>500m) the structures are known to be sub-vertical. Seismic profiles show that generally they turn to almost subhorizontal orientation with depth. Steep folding with approximately north-south oriented fold axis can explain the large-scale reflectivity patterns of the area. In this interpretation, the steep fold limbs are not imaged directly with seismic technique but fold hinges, where orientation is locally

  16. Reactivating of a mature oil field in the Finca-Yopales area, Venezuela, Using 3-D seismic

    SciTech Connect

    Sanchez, M.; Betancourt, H.

    1996-08-01

    The area of Finca-Yopales is located in the Eastern Venezuelan Basin in the Anzoategui State where Corpoven has the Trico and Yopales Norte fields. Based on the interpretation of 134 km{sup 2} of 3-D seismic and the geologic interpretation from 145 wells in the area, we define a better geological and structural model. We were also able to map 6 seismic reflectors corresponding to the units A8, F7, L4U and SI from the Oficina Formation, U2 top of Merecure Formation and the top of the Cretaceous, in order to generate a fault plane for all the area which was converted to depth with a lineal relationship which was obtained from wells available. From this interpretation we obtain the structural levels B4, J2, M1 and U2 which are references for the area, those being regional and trangressive events. The main feature of the structure is a high at the southeast of the area and three fault systems of Cretaceous, Miocene and post-Miocene age. This area has been exploited for a long time, having more than 93% of the inactive drilled wells. The total production up to April, 1995 is 59.14 MMbls; the Trico field is the most prolific, with more than 95% of the production. The sands L`s, U`s, O`s and S`s are the most prospective. This paper present the evaluation of the area and the analysis of the reservoir where we increased the computed reserves.

  17. 3-D seismic study into the origin of a large seafloor depression on the Chatham Rise, New Zealand

    NASA Astrophysics Data System (ADS)

    Pecher, I. A.; Waghorn, K. A.; Strachan, L. J.; Crutchley, G. J.; Bialas, J.; Sarkar, S.; Davy, B. W.; Papenberg, C. A.; Koch, S.; Eckardt, T.; Kroeger, K. F.; Rose, P. S.; Coffin, R. B.

    2014-12-01

    Vast areas of the Chatham Rise, east of New Zealand's South Island, are covered by circular to elliptical seafloor depressions. Distribution and size of these seafloor depressions appear to be linked to bathymetry: Small depressions several hundred meters in diameter are found in a depth range of ~500-800 m while two types of larger depressions with 2-5 km and >10 km in diameter, respectively, are present in water depths of 800-1100 m. Here we evaluate 3-D seismic reflection data acquired off the R/V Sonne in 2013 over one of the 2-5 km large depressions. We interpret that the seafloor bathymetry associated with the 2-5 km depressions was most likely created by contour current erosion and deposition. These contourite features are underlain by structures that indicate upward fluid flow, including polygonal fault networks and a conical feature that we interpret to result from sediment re-mobilization. We also discovered a set of smaller buried depressions immediately beneath the contourites. These features are directly connected to the stratigraphy containing the conical feature through sets of polygonal faults which truncate against the base of the paleo-depressions. We interpret these depressions as paleo-pockmarks resulting from fluid expulsion, presumably including gas. Based on interpretation and age correlation of a regional-scale seismic line, the paleo-pockmarks could be as old as 5.5 Ma. We suggest the resulting paleo-topography provided the initial roughness required to form mounded contourite deposits that lead to depressions in seafloor bathymetry.

  18. 3D seismic reflection imaging of nearly amagmatic oceanic lithosphere at the ultra-slow spreading Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Momoh, E. I.; Cannat, M.; Singh, S. C.; Watremez, L.; Leroy, S. D.

    2016-12-01

    Ultra-slow spreading ridges (< 10 mm/yr half-spreading rate), are characterized by a variety of mode accretion, from purely magmatic to nearly amagmatic. With the prevalence of mantle-derived peridotites and sparse volcanism on the seafloor, the easternmost portion of the ultra-slow spreading Southwest Indian Ridge (SWIR) at 64°E represents a melt-poor end-member in the global ridge system. Mantle-derived peridotites there are proposed to have been exhumed along the footwall of detachment faults (Cannat et al, 2006; Sauter et al, 2013). However, the geometry and structural styles of detachments at depth are conjectural. We show the first 3D seismic reflection images of nearly amagmatic axial oceanic lithosphere in this region. The results are from 3D processing of 2D seismic data acquired during the SISMOSMOOTH 2014 cruise along 100 m-spaced profiles in a 1.8 km wide by 24 km long box spanning the axial valley and a part of its elevated northern wall. Wide-angle tomography results from Ocean bottom Seismometer (OBS) line are used to provide a velocity structure of the crust and correlate the MCS reflection images. We image 4 classes of reflectors. The first class occurs in 2 parts as south-dipping events and can be followed in the cross-line of the survey area. The upper part terminates on the northern slope of the massif. The lower part occurs as an isolated event until half of the width of the survey area after which it appears as a continuation of the upper part. This class of reflectors may be due to the damage zone of the active axial detachment fault. The second class of reflectors occurs as north-dipping events. They extend 1 km in the cross-line. They can be interpreted as fractured zones, zones of localized serpentinization or as dikes. The third class of reflectors occurs as sub-horizontal events at depth and seems to serve as the termination of the proposed dikes/fractured zones. On the OBS result, this reflector mimics the 7.5 km/s velocity contour in

  19. Structure, Kinematics and Origin of Radial Faults: 3D Seismic Observations from the Santos Basin, offshore Brazil

    NASA Astrophysics Data System (ADS)

    Coleman, Alexander; Jackson, Christopher A.-L.

    2017-04-01

    Salt stock growth is typically accompanied by the development of geometrically and kinematically complex fault networks in the surrounding country rock. The most common networks comprise radial faults; these are characterised by low displacement (<100 m) normal faults that extend radially outwards from the salt stock into flanking strata. Radial faults are commonly observed in an arched, unpierced roof developed above a rising salt stock; in these cases, the faults are typically well-imaged seismically and likely form due to outer-arc extension during overburden stretching. Radial faults are also found at deeper structural levels, in strata flanking the diapir stem; in these cases, they are typically less well-imaged, thus their structure, kinematics and origin are less well understood. Furthermore, understanding the growth of radial faults may provide insights into hydrocarbon reservoir compartmentalisation and the evolution of neighbouring salt stocks. Here, we use high-quality 3D seismic reflection data from the Santos Basin, offshore Brazil to determine the structure and kinematics, and infer the likely origin of exceptionally well-imaged radial faults overlying and flanking a mature salt stock. Furthermore, we compare the geometric (e.g. throw, geometry, spacing, distribution etc.) and kinematic (e.g. timing of formation and duration of activity) characteristics of radial faults at both structural levels, allowing us to infer their temporal relationship and likely origins. We show that radial faults regardless of their structural level typically have aspect ratios of c. 1.8 - 2, are laterally-restricted in the vicinity of the salt, and have lengths of <3 km that vary with depth. Expansion indices of c. 1, with low throw gradients of 0.05 - 0.1 at the upper tip indicate that radial faults were likely blind. Throws range from 5 - 80 ms, with throw-maxima within 1 - 2 radii of the salt diapir. However, we note that the position of the throw maxima is not at the

  20. Investigation on 3D morphological changes of in vitro cells through digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Memmolo, Pasquale; Miccio, Lisa; Merola, Francesco; Netti, Paolo A.; Coppola, Giuseppe; Ferraro, Pietro

    2013-04-01

    We report the investigation of the identification and measurement of region of interest (ROI) in quantitative phase-contrast maps (QPMs) of biological cells by digital holographic microscopy (DHM), with the aim to analyze the 3D positions and 3D morphology together. We consider as test case for our tool the in vitro bull sperm head morphometry analysis. Extraction and measurement of various morphological parameters are performed by using two methods: the anisotropic diffusion filter, that is based on the Gaussian diffusivity function which allows more accuracy of the edge position, and the simple thresholding filter. In particular we consider the calculation of area, ellipticity, perimeter, major axis, minor axis and shape factor as a morphological parameter, instead, for the estimation of 3D position, we compute the centroid, the weighted centroid and the maximum phase values. A statistical analysis on a data set composed by N = 14 holograms relative to bovine spermatozoa and its reference holograms is reported.

  1. Investigations and improvements of digital holographic tomography applied for 3D studies of transmissive photonics microelements

    NASA Astrophysics Data System (ADS)

    Kujawinska, Malgorzata; Jozwicka, Agata; Kozacki, Tomasz

    2008-08-01

    In order to control performance of photonics microelements it is necessary to receive 3D information about their amplitude and phase distributions. To perform this task we propose to apply tomography based on projections gather by digital holography (DH). Specifically the DH capability to register several angular views of the object during a single hologram capture is employed, which may in future shorten significantly the measurement time or even allow for tomographic analysis of dynamic media. However such a new approach brings a lot of new issues to be considered. Therefore, in this paper the method limitations, with special emphasis on holographic reconstruction process, are investigated through extensive numerical experiments with special focus on 3D refractive index distribution determination.. The main errors and means of their elimination are presented. The possibility of 3D refractive index distribution determination by means of DHT is proved numerically and experimentally.

  2. Possible migration front of gas-related fluid inferred from 3D seismic in the eastern Nankai Trough

    NASA Astrophysics Data System (ADS)

    Otsuka, H.; Morita, S.; Tanahashi, M.; Ashi, J.; Nagakubo, S.

    2010-12-01

    High resolution 3D seismic survey, “Tokai-oki to Kumano-nada”, was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on a series of accordion-shaped reflectors with horizontal axis of fold back. They are connected to the edge of BSRs and alternate their polarities at every fold back hinge. We call the reflectors “Foldback Reflectors (FBRs)” in this study. Sedimentary horizons are successive across these series of reflectors with no fault displacement as a general rule. FBR generally corresponds to lateral seismic facies boundary between BSR distribution area and outside of the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components in contrast to outside of the BSR area with normal facies. Seismic velocity analysis suggests that FBRs correspond to velocity boundaries, where the dimmed faceis below the BSR coinsides with relatively low velocity. The polarities of FBRs are also consistent with such velocity changes. Such dimmed facies with low velocity and low amplitude anomaly suggests effects of gas components in the pore water. In this area, FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. The observed FBRs are clustered in northern slope of the uplifted outer ridge, whereas few FBRs are developed in the southern slope of the outer ridge with frequent compressive and strike-slip deformations related to major fault systems including the Kodaiba faults and the Tokai faults. The estimated strike directions of each FBRs are probably controlled by the dip direction of crossing formation. Another important character of FBRs is that it never crosses major unconformities into lower strata. In addition, high amplitude layers are sometimes recognized at hinges of foldbacks convex to the outside of the BSR area. These high

  3. Delineating Potential Quick-clay Areas Using High-resolution Seismic Methods: Towards a 3D Model of an Area Prone to Slide in SW Sweden

    NASA Astrophysics Data System (ADS)

    Salas Romero, S.; Malehmir, A.; Snowball, I.

    2015-12-01

    Quick clay can liquefy under increased stress and is responsible for major landslides in Sweden, Norway and Canada, but despite extensive investigations delineating quick clay remains a challenge. As part of a large multidisciplinary project, this study focuses on an area prone to quick-clay landslides in SW Sweden. P- and S-wave seismic, electrical resistivity tomography, and RMT (radio-magnetotelluric) data obtained in 2011 (Malehmir et al. 2013) suggested the presence of a coarse-grained layer of variable thickness sandwiched between clays, with quick clay above. The coarse-grained layer was assumed to accelerate the formation of quick clay, influencing its thickness. Additional geophysical data (reflection and refraction seismic, and RMT) and studies of three boreholes drilled in 2013, with the aim to intersect the coarse-grained layer, extended the area covered in 2011. Here we report on four seismic profiles (total length 3.5 km) acquired in 2013, combined with side-scan and single channel reflection seismic data along a river, which was believed to be important in the context of quick-clay landslides. Wireless (50-1C-10 Hz and 24-3C-broadband) and cabled sensors (323-28 Hz), 4-10 m apart, were used for the data acquisition of the longest profile (nearly 2 km long). Dynamite, accelerated weight-drop and sledgehammer were used as seismic sources. Simultaneous data acquisition for two parallel profiles, about 300 m apart, provides additional information. Preliminary results delineate the bedrock and its undulation near and in the river. We believe that overlying reflections are caused by the coarse-grained materials, whose lateral extension is considerably larger than previously thought. This may imply a wider area containing quick clay and hence at risk of slope failure. The new data and previous results are combined to construct a high-resolution 3D subsurface model that focuses on the coarse-grained layer and potential quick-clay areas. Malehmir A, Bastani M

  4. Impact of 3-D seismic data on the Nigerian National Petroleum Corporation/Chevron Nigeria Limited joint venture development drilling program

    SciTech Connect

    Quam, S. )

    1993-09-01

    The Nigerian National Petroleum Corporation/Chevron Nigeria Limited joint venture has been acquiring three-dimensional (3-D) seismic data over its concessions since 1984. To date, 1700 km[sup 2] have been recorded and processed at a cumulative cost of US $39 million. During 1991 - 1992, 20 development wells were drilled based directly on new 3-D seismic interpretations. These wells have added 148 million bbl of oil in new recoverable reserves, and to date have added 37,000 bbl/day to the joint venture's production. In addition, the 3-D interpretations have resulted in a sizable inventory of wells for future development drilling. The new 3-D interpretations provided more accurate pictures of fault patterns, fluid contacts, channel trends, stratigraphic continuity, and velocity/amplitude anomalies. In addition, the 3-D data were invaluable in designing low risk, directional well trajectories to tap relatively thin oil legs under large gas caps. Wells often were programmed to hit several objectives at their respective gas/oil contacts, resulting in maximized net oil sand pays and reducing the risk of gas production. In order to do this, directional [open quotes]sharpshooting,[close quotes] accurate depth conversion of the seismic time maps, was critical. By using the 3-D seismic, checkshot, and sonic data to develop a variable velocity space, well-top prognoses within 50 ft at depths of 6,000-10,000 ft were possible, and were key to the success of the program. As the joint venture acreage becomes more mature, development wells will be drilled for smaller numbers of stacked objectives, and sometimes for single sands. Highly accurate 3-D interpretations and depth conversions will become even more critical in order to tap thinner pay zones in a cost-effect manner.

  5. Investigating the Enrichment of a 3D City Model with Various CityGML Modules

    NASA Astrophysics Data System (ADS)

    Floros, G.; Dimopoulou, E.

    2016-10-01

    Recent developments in the massive 3D acquisition area made possible the generation of dense and precise 3D data, ranging from the representation of a simple building to a whole city. Nowadays, increasing urbanization, rapid growth of urban areas, and subsequently development of mega cities, are among the most important changes occurring worldwide. Therefore, developing techniques to manage these cities seems quite necessary. The aim of this paper is to investigate the enrichment of a 3D City Model with additional attributes, via appropriate CityGML Modules. The paper focuses on addressing the challenging issues that derive from a complex virtual 3D city modeling. More specifically, the paper investigates a complex built-up area, presenting and analyzing its constituting structures. Within this framework, the following CityGML modules are investigated: Bridge, Transportation Complex, CityFurniture, Land Use and Vegetation. To this purpose, the BIM-Standard software Trimble SketchUp and the data conversion tool FME are used. The processes of both modeling and converting are analyzed in detail. General conclusions and future research considerations are presented.

  6. Leveraging 3D Wheeler Diagrams and relative time mapping in seismic data to improve stratigraphic interpretation: Application, Assumptions, and Sequence Stratigraphic Revelations

    NASA Astrophysics Data System (ADS)

    Goggin, L. R.

    2014-12-01

    Our understanding of subsurface stratigraphic relationships is guided by stratigraphic concepts that were developed using many varieties and scales of data including paleontological samples, cuttings and core, outcrop analogs, well logs, and seismic. Subsurface stratigraphic correlations are strongly influenced by the type, density, and distribution of the data available. The exploration geologist typically interprets 2D and 3D seismic reflections to define prospects and plays. In structurally simple areas, he or she often assumes that seismic reflectors mark depositional boundaries that are essentially time-synchronous events represented by a single wavelet character. In reality, seismic reflectors usually display spatial wavelet variability, seldom resolve individual beds and are the product of the amplitude expression of a range of lithologic changes that encompasses a range of geologic time and depositional processes. Our assumption that seismic reflections are time-synchronous can lead to errors in stratigraphic correlation that only become evident when our prediction of well or field performance is unrealized. To mitigate the potential for this correlation error, we must modify how we interpret seismic data. In this presentation we will focus on the concept of defining or approximating time-correlative surfaces in seismic data, leverage concepts of the Wheeler transform to place these seismic reflectors into the relative time domain and then examine the diachronous nature of these time-mapped surfaces in 3D. We will then explore how the 3D mapping of time-correlative surfaces fits sequence stratigraphic concepts and discuss whether this new approach requires us to change our interpretation paradigms.

  7. Hypocenter relocation using a fast grid search method and a 3-D seismic velocity model for the Sumatra region

    SciTech Connect

    Nugroho, Hendro; Widiyantoro, Sri; Nugraha, Andri Dian

    2013-09-09

    Determination of earthquake hypocenter in Indonesia conducted by the Meteorological, Climatological, and Geophysical Agency (MCGA) has still used a 1-D seismic velocity model. In this research, we have applied a Fast Grid Search (FGM) method and a 3-D velocity model resulting from tomographic imaging to relocate earthquakes in the Sumatran region. The data were taken from the MCGA data catalog from 2009 to 2011 comprising of subduction zone and on land fault earthquakes with magnitude greater than 4 Mw. Our preliminary results show some significant changes in the depths of the relocated earthquakes which are in general deeper than the depths of hypocenters from the MCGA data catalog. The residual times resulting from the relocation process are smaller than those prior to the relocation. Encouraged by these results, we will continue to conduct hypocenter relocation for all events from the MCGA data catalog periodically in order to produce a new data catalog with good quality. We hope that the new data catalog will be useful for further studies.

  8. 3-D seismic results in the discovery of significant reserves bypassed for 55 years in the Chocolate Bayou Field

    SciTech Connect

    Pennington, A.; Plant, C.; Davis, C.

    1994-12-31

    The Chocolate Bayou Field is located 25 miles south of Houston, in Southeast Brazoria County, Texas. Discovered in 1938, the field has produced over 2 trillion cubic feet of natural gas and 65 million barrels of oil from approximately 30 sands and 300 wellbores. The majority of the production is from the sands of the upper and middle Frio (Oligocene) section. Accumulation is found on structural highs on both the downthrown and upthrown side of a major basinward growth fault. A 3-D seismic survey was conducted over the field in 1988 in an effort to locate bypassed reserves. Interpretation of the data revealed and unexpected paleo structure associated with a buried and previously undetected counter-regional fault located almost 3 miles south of the structural crest at the Upper Frio level. Detailed structural and isochron mapping with adequate depth conversions indicated that the structure was prospective for trapping of the Lower Frio Sand which were well developed but wet under the Upper Frio structural crest. Although the feature was located on the absolute edge of the survey, the data were adequate to locate two wells which have now been completed in the Lower Frio (RA{sub 4}) section. The sands ranged in thickness from 65 to 115 feet of net pay with porosities from 27 to 30% with sustained production rates in excess of 10,000 million cubic feet of gas and 140 barrels of oil per day per completion.

  9. Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect

    SciTech Connect

    Frary, R.; Louie, J.; Pullammanappallil, S.; Eisses, A.

    2016-08-01

    Roxanna Frary, John N. Louie, Sathish Pullammanappallil, Amy Eisses, 2011, Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract T13G-07.

  10. Evaluation of geological conditions for coalbed methane occurrence based on 3D seismic information: a case study in Fowa region, Xinjing coal mine, China

    NASA Astrophysics Data System (ADS)

    Li, Juanjuan; Li, Fanjia; Hu, Mingshun; Zhang, Wei; Pan, Dongming

    2017-04-01

    The research on geological conditions of coalbed methane (CBM) occurrence is of great significance for predicting the high abundance CBM rich region and gas outburst risk area pre-warning. The No. 3 coal seam, in Yangquan coalfield of Qinshui basin, is the research target studied by 3D seismic exploration technique. The geological factors which affect CBM occurrence are interpreted based on the 3D seismic information. First, the geological structure (faults, folds, and collapse columns) is found out by the 3D seismic structural interpretation and the information of buried depth and thickness of the coal seam is calculated by the seismic horizons. Second, 3D elastic impedance (EI) and natural gamma attribute volumes are generated by prestack EI inversion and multi-attribute probabilistic neural network (PNN) inversion techniques which reflect the information of coal structure types and lithology of the roof and floor. Then, the information of metamorphic degree of seam and hydrogeology conditions can be obtained by the geological data. Consequently, geological conditions of CBM occurrence in No. 3 coal seam are evaluated which will provide scientific reference for high abundance CBM rich region prediction and gas outburst risk area pre-warning.

  11. Evaluation of geological conditions for coalbed methane occurrence based on 3D seismic information: a case study in Fowa region, Xinjing coal mine, China

    NASA Astrophysics Data System (ADS)

    Li, Juanjuan; Li, Fanjia; Hu, Mingshun; Zhang, Wei; Pan, Dongming

    2017-03-01

    The research on geological conditions of coalbed methane (CBM) occurrence is of great significance for predicting the high abundance CBM rich region and gas outburst risk area pre-warning. The No. 3 coal seam, in Yangquan coalfield of Qinshui basin, is the research target studied by 3D seismic exploration technique. The geological factors which affect CBM occurrence are interpreted based on the 3D seismic information. First, the geological structure (faults, folds, and collapse columns) is found out by the 3D seismic structural interpretation and the information of buried depth and thickness of the coal seam is calculated by the seismic horizons. Second, 3D elastic impedance (EI) and natural gamma attribute volumes are generated by prestack EI inversion and multi-attribute probabilistic neural network (PNN) inversion techniques which reflect the information of coal structure types and lithology of the roof and floor. Then, the information of metamorphic degree of seam and hydrogeology conditions can be obtained by the geological data. Consequently, geological conditions of CBM occurrence in No. 3 coal seam are evaluated which will provide scientific reference for high abundance CBM rich region prediction and gas outburst risk area pre-warning.

  12. 3D geological to geophysical modelling and seismic wave propagation simulation: a case study from the Lalor Lake VMS (Volcanogenic Massive Sulphides) mining camp

    NASA Astrophysics Data System (ADS)

    Miah, Khalid; Bellefleur, Gilles

    2014-05-01

    The global demand for base metals, uranium and precious metals has been pushing mineral explorations at greater depth. Seismic techniques and surveys have become essential in finding and extracting mineral rich ore bodies, especially for deep VMS mining camps. Geophysical parameters collected from borehole logs and laboratory measurements of core samples provide preliminary information about the nature and type of subsurface lithologic units. Alteration halos formed during the hydrothermal alteration process contain ore bodies, which are of primary interests among geologists and mining industries. It is known that the alteration halos are easier to detect than the ore bodies itself. Many 3D geological models are merely projection of 2D surface geology based on outcrop inspections and geochemical analysis of a small number of core samples collected from the area. Since a large scale 3D multicomponent seismic survey can be prohibitively expensive, performance analysis of such geological models can be helpful in reducing exploration costs. In this abstract, we discussed challenges and constraints encountered in geophysical modelling of ore bodies and surrounding geologic structures from the available coarse 3D geological models of the Lalor Lake mining camp, located in northern Manitoba, Canada. Ore bodies in the Lalor lake VMS camp are rich in gold, zinc, lead and copper, and have an approximate weight of 27 Mt. For better understanding of physical parameters of these known ore bodies and potentially unknown ones at greater depth, we constructed a fine resolution 3D seismic model with dimensions: 2000 m (width), 2000 m (height), and 1500 m (vertical depth). Seismic properties (P-wave, S-wave velocities, and density) were assigned based on a previous rock properties study of the same mining camp. 3D finite-difference elastic wave propagation simulation was performed in the model using appropriate parameters. The generated synthetic 3D seismic data was then compared to

  13. Sound levels from a 3D seismic survey in the Porcupine Basin: Validation and Calibration of a Sound Propagation Model using Observed Data

    NASA Astrophysics Data System (ADS)

    Crawford, S.; Brown, C.; McKeown, E.; Stapleton, F.; McCauley, R.; Duncan, A.; White, M. G.

    2016-02-01

    Following Ireland's 2015 Atlantic Margin Oil and Gas Exploration Licensing Round, the Porcupine Basin continues to be a significant site for seismic exploration activities, which commonly use air guns as an impulsive sound source, to investigate sub-bottom structure. Recent literature has reported on the environmental implications of marine seismic surveys, highlighting alarmed and avoidance behaviour in several marine mammal species as a common response to air gun signals. The European Habitats Directive (EC: 92/43/EEC) orders the protection of all cetacean species in European waters, 23 of which inhabit Irish waters for at least part of the year. As such, underwater acoustic monitoring and mapping has been targeted as a research priority under the European Union's Marine Strategy Framework Directive. The findings will be essential for designing and implementing appropriate regulation regarding underwater noise. A collection of sound propagation codes have been made freely available through the Centre for Marine Science and Technology's Acoustic Toolbox User Interface and Post-Processor (AcTUP) at Curtin University. In this study, RAMGeo (available in AcTUP), a range-dependent technique which employs the Parabolic Equation (PE), was used to model the transmission loss (TL) of low frequency noise across real, range-dependent 2D source-to-receiver sections from the Porcupine Basin. The TL values computed in the model are validated against their corresponding observed values, which were measured during a research cruise in July 2014, to coincide with 3D seismic operations in the area at locations across the Basin. Based on discrepancies arising from validation results, the geoacoustic environment is adjusted for a closer approximation to the behaviour of the real environment. In doing this, the sound propagation model is refined and then calibrated for the Porcupine Basin. The findings and limitations of the study are evaluated before implications of the research and

  14. Do fault-related folds follow the same scaling law as their associated faults? A study using 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Pitcher, Eleanor; Imber, Jonathan

    2016-04-01

    Fractal distributions are largely agreed to follow a power-law distribution. Power-law scaling relationships describe the size distribution of fault lengths or displacements. Being able to identify these scaling properties provides a powerful tool for predicting the numbers of geological structures, such as small-scale faults in sedimentary basins that are below the resolution of seismic reflection data. The aim of this study is to determine whether fault-related folds follow the same power law scaling properties, or if they follow a different scaling law. We use TrapTester to interpret a 3D seismic volume from the Gulf of Mexico to construct fault planes and cut-off lines along selected horizons in the vicinity of fault upper tip lines. Fault-related folds are particularly well developed above steeply plunging tip lines, but are discontinuous along the strike of the fault plane. Folding is less well developed on horizons that intersect, or lie close to, the locus of maximum throw (bullseye) of the fault plane. We then measured fold amplitudes and fault throws across these same horizons using a one-dimensional multi-line sampling approach. Graphs of fault throw and fold amplitude vs. distance parallel to fault strike show that folds occur where there is no resolvable fault throw, and that fault throw and fold amplitudes show an approximately inverse relationship. Close to the locus of maximum throw, there is largely just faulting, whilst at the upper tip line folding predominates. By plotting cumulative frequency against throw for the fault and fold data we can investigate whether the data follow a power law, log normal or exponential distribution. Plotting the data on log vs. log (power law), linear vs. log (log normal) and log vs. linear (exponential) axes allow us to establish which displays the best "straight-line fit". We observed that the fault throw data satisfied a straight-line on a log vs. log graph - implying a power law distribution - and also returned

  15. 3D modeling of seismic waves propagation in the Israeli continental shelf: soft sediments, buried canyons and their effects.

    NASA Astrophysics Data System (ADS)

    Tsesarsky, M.; Volk, O.; Shani-Kadmiel, S.; Gvirtzman, Z.

    2016-12-01

    Sedimentary wedges underlay many coastal areas, specifically along passive continental margins. Although a large portion of the world`s population is concentrated along coastal areas, relatively few studies investigated the seismic hazard related to internal structure of these wedges. This is particularly important, when the passive margin is located in proximity to active plate boundaries. Sedimentry wedges have low angles compared to fault bounded basins, hence commonly treated using 1D methods. In various locations the sedimentary wedges are transected by deep buried canyons typically filled with sediments softer than their surrounding bedrock. Such structures are found is the Mediterranean coast of Israel. Here, a sedimentary wedge and buried canyons underlay some of the country's most densely populated regions. Seismic sources can be found both at sea and on land at epicentral distances ranging from 50 to 200 km. Although this region has a proven seismic record, it has, like many other parts of the world, limited instrumental coverage and long return periods. This makes assessment of ground motions in a future earthquake difficult and highlights the importance of non-instrumental methods. We employ numerical modeling (SW4 FD code) to study seismic ground motions and their amplification atop the sedimentary wedge and canyons. This goal is a part of a larger objective aiming at developing a systematic approach for distinction between individual contributions of basin structures to the highly complex overall basin response. We show that the sedimentary wedge and buried canyon both exhibit a unique response and modeling them as one-dimensional structures could significantly underestimate seismic hazard. The sedimentary wedge exhibit amplification ratios, relative to a horizontally layered model, up to a factor of 2. This is mainly due to the amplification of Rayleigh waves traveling into the wedge from its thin side. The buried canyon structure shows a simple

  16. 3-D seismic delineation and geologic explanation of channelization in the Frio Formation of Javelina/East McCook Field, Hidalgo County, Texas

    SciTech Connect

    Gibson, J.L.

    1994-09-01

    Sinuous, channel-form features were recognized on seismic amplitude time-slice maps of the shallow Oligocene Frio Formation on several Shell proprietary 3-D seismic surveys in west-central Hidalgo County, Texas. A case study of channel morphologies observed in the Frio Formation within the 50 mi{sup 2} 3-D seismic survey over Javelina/East McCook field was undertaken to better understand the distribution, lithology, origin, and hydrocarbon potential of these features. Ten separate channel-like amplitude features are observed in flattened time slices within a 200 m (approximately 1100 ft) interval on 3-D seismic. The channels have various azimuthal orientations and varying degrees of sinuosity. Several of the features have lengths that span the 3-D survey area (10 mi); apparent channel widths range from 200 to 2000 ft. The channelized seismic events tie to an interval of interbedded mudstones and claystones with siltstones. Two of the channels seen on seismic, and which were penetrated by wells, correlate to siftstone and mudstone intervals that have gross thicknesses of 30 to 60 ft. The lithologies and dimensions of the two channels indicate that they are probably small mudstone/siltstone-filled tributary/distributary channels deposited in a coastal floodplain environment; a comparison of the apparent channel dimensions to the dimensions of small channels/bayous of the modern-day Texas Gulf Coast supports this interpretation. Correlation of wells adjacent to the channels indicates that sandy point-bar facies are not present in association with the channel fill, which discounts the idea that high-quality reservoirs are flanking these particular mud-filled channels.

  17. Mapping the North Sea base-Quaternary: using 3D seismic to fill a gap in the geological record

    NASA Astrophysics Data System (ADS)

    Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

    2014-05-01

    The identification and mapping of the base-Quaternary boundary in the central parts of the North Sea is problematic due to the change from an unconformable transition between Pliocene and Pleistocene deltaic deposits in the southern North Sea to a conformable one further north (Sejrup et al 1991; Gatliff et al 1994). The best estimates of the transition use seismic reflection data to identify a 'crenulated reflector' (Buckley 2012), or rely on correlating sparse biostratigraphy (Cameron et al 1987). Recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) allows greater confidence in the correlation to a regional 3D seismic dataset and show that the base-Quaternary can be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The mapped horizon is presented here alongside the difference between this new interpretation and the previously interpreted base-Quaternary (Buckley 2012). The revised base-Quaternary surface reaches a depth of 1248 ms TWT or approximately 1120 m (assuming average velocity of 1800 m/s) showing an elongate basin shape that follows the underlying structure of the Central Graben. The difference between the revised base-Quaternary and the traditional base-Quaternary reaches a maximum of over 600 ms TWT or approximately 540 m in the south-west with over 300 ms TWT or approximately 270 m at the Josephine well (56° 36.11'N, 2° 27.09'E) in the centre of the basin. Mapping this new base-Quaternary allows for the interpretation of the paleo-envionrment during the earliest Quaternary. Seismic attribute analysis indicates a deep water basin with sediment deposition from multiple deltas and redistribution by deep

  18. Rock formation characterization for CO2-EOR and carbon geosequestration; 3D seismic amplitude and coherency anomalies, Wellington Field, Kansas, USA

    USGS Publications Warehouse

    Ohl, D.; Raef, A.; Watnef, L.; Bhattacharya, S.

    2011-01-01

    In this paper, we present a workflow for a Mississipian carbonates characterization case-study integrating post-stack seismic attributes, well-logs porosities, and seismic modeling to explore relating changes in small-scale "lithofacies" properties and/or sub-seismic resolution faulting to key amplitude and coherency 3D seismic attributes. The main objective of this study is to put emphasis on reservoir characterization that is both optimized for and subsequently benefiting from pilot tertiary CO2-EOR in preparation for future carbon geosequestration in a depleting reservoir and a deep saline aquifer. The extracted 3D seismic coherency attribute indicated anomalous features that can be interpreted as a lithofacies change or a sub-seismic resolution faulting. A 2D finite difference modeling has been undertaken to understand and potentially build discriminant attributes to map structural and/or lithofacies anomalies of interest especially when embarking upon CO2-EOR and/or carbon sequestration monitoring and management projects. ?? 2011 Society of Exploration Geophysicists.

  19. Weapons test seismic investigations at Yucca Mountain

    SciTech Connect

    Phillips, J.S.; Shephard, L.E.; Walck, M.C.

    1991-01-01

    Yucca Mountain, located on and adjacent to the Nevada Test Site, is being characterized as part of an ongoing effort to identify a potential high-level nuclear waste repository. This site will be subjected to seismic ground motions induced by underground nuclear explosions. A knowledge of expected ground motion levels from these tests will enable the designers to provide for the necessary structural support in the designs of the various components of the repository. The primary objective of the Weapons Test Seismic Investigation project is to develop a method to predict the ground motions expected at the repository site as a result of future weapons tests. This paper summarizes the data base presently assembled for the Yucca Mountain Project, characteristics of expected ground motions, and characterization of the two-dimensional seismic properties along paths between Yucca Mountain and the testing areas of the Nevada Test Site.

  20. Inverse Problem for 3D coupled Flow-Geomechanics Models and Induced Seismicity: Application to Subsurface Characterization and Seismicity Forecasting in Geologic CO2 Storage

    NASA Astrophysics Data System (ADS)

    Castineira, D.; Jha, B.; Juanes, R.

    2016-12-01

    Carbon Capture and Sequestration (CCS) is regarded as a promising technology to mitigate rising CO2 concentrations in the atmosphere from industrial emissions. However, as a result of the inherent uncertainty that is present in geological structures, assessing the stability of geological faults and quantifying the potential for induced seismicity is a fundamental challenge for practical implementation of CCS. Here we present a formal framework for the solution of the inverse problem associated with coupled flow and geomechanics models of CO2 injection and subsurface storage. Our approach builds from the application of Gaussian Processes, MCMC and posterior predictive analysis to evaluate relevant earthquake attributes (earthquake time, location and magnitude) in 3D synthetic models of CO2 storage under geologic, observational and operational uncertainty. In our approach, we first conduct hundreds of simulations of a high-fidelity 3D computational model for CO2 injection into a deep saline aquifer, dominated by an anticline structure and a fault. This ensemble of realizations accounts for uncertainty in the model parameters (including fault geomechanical and rock properties) and observations (earthquake time, location and magnitude). We apply Gaussian processes (GP) to generate a valid surrogate that closely approximates the behavior of the high fidelity (and computationally intensive) model, and apply hyperparameter optimization and cross-validation techniques in the solution of this multidimensional data-fit problem. The net result of this process is the generation of a fast model that can be effectively used for Bayesian analysis. We then implement Markov chain Monte Carlo (MCMC) to determine the posterior distribution of the model uncertain parameters (given some prior distributions for those parameters and given the likelihood defined in this case by the GP model). Our results show that the resulting posterior distributions correctly converge towards the "true

  1. Fast 3d Hybrid Seismic Modeling: Ray-fd Approach For Elastic Models With Locally Complex Structures

    NASA Astrophysics Data System (ADS)

    Oprsal, I.; Brokesova, J.; Faeh, D.; Giardini, D.

    Hybrid approaches may find broad applications wherever full source, path,and site effects modeling methods are too expensive. A new efficient hybrid method allowing to compute seismic wavefield in large 3D elastic models containing a complex local structure embedded in a large, but considerably simpler, structure is designed. This hybrid method combines the ray approach in the large simple structure with the finite difference (FD) approach in the local complex structure. The hybrid method is based on two successive steps. In the 1st one, the source and path information is carried by wavefield propagating in the large simple structure. This wavefield, calculated by the ray method, is incident at the points along a two-fold formal boundary (excitation box, EB) surrounding that part of the model which is to be replaced by the complex medium in the 2nd step. 3D rays are necessary due to ar- bitrary source-EB configuration, even in case the 1st step structure is less dimensional (2D, 1D, homogeneous). Along EB, the ray endpoints may be distributed sparsely thanks to relative simplicity of the structure. This reduces computer time requirements and also the size of the excitation file saved on the disk. The ray wavefield along EB provides (after interpolation in space and time) the input for the second step consisting in calculating the complete wavefield by the 3D FD method on irregular grids. The FD computational domain contains the EB and its close vicinity. The 2nd step model differs from the 1st step model only inside the EB where the local complex structure is inserted. To verify the consistency between the 1st and the 2nd step binding, the 2nd step computation can be performed on (unchanged) 1st step model ('replication test'). This should give the same wavefield as the 1st step inside, and zero wavefield outside the EB. The EB remains fully permeable for all waves propagating within the FD domain. Provided the 1st step structure does not contain too many layers

  2. 3-D deformation rates and processes driving seismicity in the Western Alps and Pyrenees (southern France, northern Spain, northern Italy)

    NASA Astrophysics Data System (ADS)

    Vernant, Philippe; Mazzotti, Stephane; Masson, Christine; Ninh NGuyen, Hai; Doerflinger, Erik; Chéry, Jean; Khazaradze, Giorgi; Asensio, Eva

    2017-04-01

    Although subject to significant earthquakes, the region covering the Western Alps and Pyrenees in southern France, northern Spain, and northern Italy is characterized by very slow deformation rates (below 1 mm a-1), leading to ongoing debates regarding the driving processes and characteristics of this seismicity. We present a new 3-D velocity field for nearly 500 GPS sites covering this area, with two main objectives: (1) Precisely define the level of velocity and strain rate signals that can be extracted from the GPS data, and (2) Characterize the patterns and amplitude of present-day deformation in both the Western Alps and Pyrenees to help constrain the geodynamic processes at play. Statistical analyses of the GPS time series shows that a horizontal (resp. vertical) precision level of 0.2 mm a-1 can be achieved for series of 6 years (resp. 9 years), and that the velocity field for the entire Western Alps - Pyrenees region is stable at 0.2 mm a-1, indicating that horizontal deformation, where present, must be below this threshold. Significant horizontal strain rates are detected in the western Pyrenees, with up to 4 × 10-9 a-1 NNE-SSW extension, and to a lower level in the Western Alps (< 1 × 10-9 a-1 E-W extension). In contrast, we identify significant uplift rates in the Western Alps (up to 2 mm a-1) but not in the Pyrenees (0.1 ± 0.2 mm a-1). As shown by numerical models and by the correlation between site elevations and uplift rates, fast uplift in the northern part of the Western Alps can be explained for the most part by postglacial rebound following the Würm glaciation. In contrast, the very slow uplift rates in the southern Western Alps and in the Pyrenees may be accounted for by erosion-induced rebound. These results suggest that the primary driving mechanisms for present-day seismicity in the Western Alps, the Pyrenees, and their foreland basins may be visco-elastic rebound. Other processes, such as regional tectonics, post-orogenic collapse, or

  3. Geomorphologic characteristics of debris flows in the Ulleung Basin, East Sea (Japan Sea) interpreted from 3-D seismic data and their implications

    NASA Astrophysics Data System (ADS)

    MO, C.; Park, G.; Lee, G.; Yi, B.; Yoo, D.

    2012-12-01

    We processed and analyzed the 3-D seismic data from the southern central part of the Ulleung Basin, East Sea (Japan Sea) to investigate the geomorphologic characteristics of the debris flows. The data processing included dip moveout, post-stack migration, and acquisition footprint removal. The curvature attributes of the seafloor show numerous bubble- or dot-like features that form a N-S to NNE-SSW trending narrow (ca. 2 km wide) zone in the western part of the area. The bubble-like features correspond to the irregular seafloor in the seismic profiles. At least nine debris flows, which advanced largely north and northeastward, were identified from the seafloor to the sub-seafloor depth of about 300 m. The debris flows are lens- or wedge-shaped in cross section, characterized by structureless or transparent to chaotic internal reflections, and elongate or lobate in plan view. The largest debris flow exceeds the 3D seismic data coverage (16 km by 25 km) and its thickness reaches about 60 m. Some debris flows are very thin and amalgamated or coalesced, making it difficult to interpret the individual flows. The similarity and curvature attributes of the basal contact of some debris flows show numerous long grooves, erosional scars, and bubble- or dot-like features similar to those seen in the seafloor. The grooves, interpreted to be caused by large clasts imbedded at the base of the debris flows, diverge and become slightly wider (< 500 m in width) downslope. The grooves are better imaged away from the main transport axis of the debris flows where the bubble-like features obscure the grooves. The zone with the bubble-like features in the seafloor coincides with the main axis of the thickest and most extensive debris flow. The bubble-like features in both the seafoor and the basal contact of the debris flows may represent the active fluid seeps. The decrease in the number of the bubble-like features away from the axis of the debris flows probably suggest decreasing pore

  4. A successful 3D seismic survey in the ``no-data zone,`` offshore Mississippi delta: Survey design and refraction static correction processing

    SciTech Connect

    Carvill, C.; Faris, N.; Chambers, R.

    1996-12-31

    This is a success story of survey design and refraction static correction processing of a large 3D seismic survey in the South Pass area of the Mississippi delta. In this transition zone, subaqueous mudflow gullies and lobes of the delta, in various states of consolidation and gas saturation, are strong absorbers of seismic energy. Seismic waves penetrating the mud are severely restricted in bandwidth and variously delayed by changes in mud velocity and thickness. Using a delay-time refraction static correction method, the authors find compensation for the various delays, i.e., static corrections, commonly vary 150 ms over a short distance. Application of the static corrections markedly improves the seismic stack volume. This paper shows that intelligent survey design and delay-time refraction static correction processing economically eliminate the historic no data status of this area.

  5. Release of thermogenic-methane in the Hammerfest Basin after the Last Glacial Maximum. Indications from numerical modelling and 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Anka, Z.; Rodrigues, E.; Ostanin, I.; di Primio, R.; Stoddart, D.; Horsfield, B.

    2012-04-01

    The Hammerfest Basin, located in the SW Barents Sea, is characterized by present-day under-filled hydrocarbon accumulations, which are known to have leaked in the past (Dimakis, 1998; Ohm et al. 2008). Late Cenozoic erosion and high latitude glaciations are thought to have driven the redistribution and leakage of these thermogenic fluids providing a source of thermogenic methane to the hydrosphere. The timing, extent and driving factors for the leakage events are still largely unconstrained. Therefore, we investigated present and past leakage of liquid and gaseous hydrocarbons over the Snøhvit and Albatross gas fields of the Hammerfest Basin and analyse its dynamics in response to multiple phases of tectonic uplift and glaciations by means of a combined approach of numerical modelling and interpretation of a high resolution 3D seismic reflection cube. Our data-constrained 3D basin model of the basin allowed us to quantify the masses of hydrocarbons generated, accumulated and eventually leaked from the reservoirs during the evolution of the basin. Particular emphasis was placed on analysing the fate of leaked volumes of methane within the dynamics of Plio-Quaternary glacial cycles and possible formation or destabilization of gas hydrate deposits. Besides reproducing quite accurately the composition and volume of the hydrocarbons -particularly the gaseous phase- present in the main reservoirs, the model predicts the development of overpressures in the reservoirs due to the ice loading of the basin during the glacial periods. Predicted reservoir pressure fluctuations derived from cyclic loading-unloading during the glacial-interglacial periods are up to 5 MPa. The under-filled nature of the present-day accumulations would result from leakage events during the episodes of glacial retreat, in the transition from glacial to interglacial periods. Considerations of the gas hydrate stability conditions in the basin during the time span between 1.00Ma and ≈11,500 years

  6. Investigation of Presage 3D Dosimetry as a Method of Clinically Intuitive Quality Assurance and Comparison to a Semi-3D Delta4 System

    NASA Astrophysics Data System (ADS)

    Crockett, Ethan Van

    The need for clinically intuitive metrics for patient-specific quality assurance in radiation therapy has been well-documented (Zhen, Nelms et al. 2011). A novel transform method has shown to be effective at converting full-density 3D dose measurements made in a phantom to dose values in the patient geometry, enabling comparisons using clinically intuitive metrics such as dose-volume histograms (Oldham et al. 2011). This work investigates the transform method and compares its calculated dose-volume histograms (DVHs) to DVH values calculated by a Delta4 QA device (Scandidos), marking the first comparison of a true 3D system to a semi-3D device using clinical metrics. Measurements were made using Presage 3D dosimeters, which were readout by an in-house optical-CT scanner. Three patient cases were chosen for the study: one head-and-neck VMAT treatment and two spine IMRT treatments. The transform method showed good agreement with the planned dose values for all three cases. Furthermore, the transformed DVHs adhered to the planned dose with more accuracy than the Delta4 DVHs. The similarity between the Delta4 DVHs and the transformed DVHs, however, was greater for one of the spine cases than it was for the head-and-neck case, implying that the accuracy of the Delta4 Anatomy software may vary from one treatment site to another. Overall, the transform method, which incorporates data from full-density 3D dose measurements, provides clinically intuitive results that are more accurate and consistent than the corresponding results from a semi-3D Delta 4 system.

  7. Shallow Gas and Gas Hydrates in the Barents Sea Imaged by High-Resolution 3D Seismic Data

    NASA Astrophysics Data System (ADS)

    Planke, S.; Eriksen, O.; Eriksen, F. N.; Bunz, S.; Berndt, C.

    2012-12-01

    Shallow gas and gas hydrates are potential hazards for the petroleum industry, but may also represent future resources. Detailed mapping of shallow gas and gas hydrates is important to reduce drilling risks, to exploit hydrocarbon resources, and to better understand procesesse of gas migration and accumulation. We have collected two high resolution 3D seismic cubes of 10-20 km2 in areas with shallow gas in the Barents Sea. The cubes were acquired using the P-Cable system in water depths of 300-500 m with the vessel R/V Jan Mayen. The data were processed using the RadexPro software and a standard sequence including geometry, tide corrections, binning, filtering, and migration. Two main sedimentary sequences are present in the data, a sub-horizontal glacial package overlying a westward-dipping Paleogene sequence. The seabed is characterized by up to 15 m deep glacial ploughmarks. An upper regional unconformity (