Science.gov

Sample records for offshore stratigraphic test

  1. Norwegian Offshore Stratigraphic Lexicon (NORLEX)

    NASA Astrophysics Data System (ADS)

    Gradstein, Felix M.; Hammer, Oyvind; Brunstad, Harald; Charnock, Mike; Hellem, Terje; Sigve Lervik, Kjell; Anthonissen, Erik

    2010-05-01

    The Norwegian Offshore Stratigraphic Lexicon (NORLEX) provides a relational stratigraphic database for the North Sea, Norwegian Sea, Barents Sea and Svalbard. Both regional lithostratigraphy and biostratigraphy are being substantially updated, following guidelines laid out in the International Stratigraphic Guide. The main body of information developed is available as a petroleum consortium (oracle-style) database, and the new lithostratigraphic definitions as a public domain (paper) document. NORLEX is presented as a browsing website via the internet at http://www.nhm.uio.no/norlex. Seismic cross-sections, core photographs, well logs, field outcrops, microfossil occurrences and other vital attributes are relationally cross-linked. In addition, there are menus for instantly finding updated formation and member tops or microfossil events in all wells, plus a map contouring routine for unit thicknesses and depths. Several new initiatives will expand data and user coverage: 1. Overhaul of Mesozoic stratigraphy, especially Triassic and Cretaceous, in the Barents Sea. 2. Coverage of East Greenland 3. Linkage to UK and Belgium and The Netherlands surface and subsurface stratigraphy 4. Creation of a Sequence Stratigraphic Framework for specific regions. 5. A national microfossil atlas to support zonations 6. Tight linkage to the basin datapacks in TimeScaleCreator Pro, as developed for Australia, New Zealand, Brasil, Gulf of Mexico, Canada and Russia. NORLEX may thus evolve to become STRATLEX, covering many basin regions.

  2. Sequence stratigraphic framework of Neogene strata in offshore Nigeria

    SciTech Connect

    Pacht, J.A.; Bowen, B.E.; Hall, D.J.

    1996-08-01

    The western portion of the Nigerian continental margin (Dahomey Basin) exhibits stable to moderately unstable progradation. Systems tracts are similar to those described by Vail for stable progradational margins. In contrast, strata off the central and eastern portions of the Nigerian coast (Niger Delta Complex) exhibit highly unstable progradation, and systems tracts are similar to those in Neogene strata of the offshore Gulf of Mexico. Lowstand basin floor fans in both areas are defined by a well-developed upper reflection. This reflection downlaps along the sequence boundary or abuts against the downthrown side of a growth fault surface. Most lower lowstand (slope fan) strata exhibit discontinuous to semi-continuous subparallel reflections. However, this systems tract also contains channel complexes characterized by chaotic bedding with small bright spots and less common large channels, which exhibit concave-upward reflections. In the western portion of the study area, lower lowstand deposits commonly pinch out on the slope. Deposition occurred largely from point sources. In contrast, contemporaneous shallow-water facies are developed in lower lowstand systems tracts in the Niger Delta Complex. Deposition occurred along a line source. Large amplitude anomalies in the upper lowstand (prograding wedge) suggest well-developed sheet sands occur in shallow-water and deep-water in the Niger Delta complex. However, in the Dahomey Basin there is little evidence of deep-water sands in this interval. The transgressive and highstand systems tracts are usually very thin in outer shelf to basin floor strata in both areas. Both the Dahomey Basin and Niger Delta Complex exhibit different stratigraphic geometries, and therefore, require different exploration strategies.

  3. Sedimentary fill and stratigraphic traps of Porcupine basin, offshore Ireland

    SciTech Connect

    Macurda, D.B. Jr.

    1986-05-01

    The Porcupine basin, off the southwest coast of Ireland, is a triangular north-south re-entrant into the present-day continental shelf. This aulacogen was formed in the Jurassic during the opening of the North Atlantic. A seismic stratigraphic investigation of the southern part of the basin has shown the complex evolution of the sedimentary fill from shallow to deep water facies, resulting in several stratigraphic traps. The central axis of the basin is dominated by a volcanic ridge. Part of the early sedimentary fill was intermittently covered by volcanic flows. The final stage of thin initial siliciclastic infill was the development of an extensive alluvial fan or fan-delta complex along the eastern basin margin. Aerially extensive carbonate sedimentation occurred during the Cretaceous, including a north-south reef tract more than 20 km wide in the eastern part of the basin. Increased subsidence resulted in the deposition of deep water siliciclastics in the Tertiary. The most prominent of these is a series of lower Tertiary submarine fans that were sourced from the western, northern, and eastern margins of the aulacogen. The early portions of the fans correlate well basin-wide; their later history is much more complex, with younger lobes up to 25 km wide developing south of their precursors. Subsequent onlap fill deposits provide an excellent seal. Sedimentation in the late Tertiary has included both high-energy and low-energy deep water deposits. The complex fill of the aulacogen has set up several stratigraphic plays, including carbonate reefs, alluvial fans of fan deltas, and submarine fans. Seismic amplitude anomalies in the latter suggest the heat flow has been sufficient to generate hydrocarbons to fill some of the traps.

  4. Numeric stratigraphic modeling: Testing sequence Numeric stratigraphic modeling: Testing sequence stratigraphic concepts using high resolution geologic examples

    SciTech Connect

    Armentrout, J.M.; Smith-Rouch, L.S.; Bowman, S.A.

    1996-08-01

    Numeric simulations based on integrated data sets enhance our understanding of depositional geometry and facilitate quantification of depositional processes. Numeric values tested against well-constrained geologic data sets can then be used in iterations testing each variable, and in predicting lithofacies distributions under various depositional scenarios using the principles of sequence stratigraphic analysis. The stratigraphic modeling software provides a broad spectrum of techniques for modeling and testing elements of the petroleum system. Using well-constrained geologic examples, variations in depositional geometry and lithofacies distributions between different tectonic settings (passive vs. active margin) and climate regimes (hothouse vs. icehouse) can provide insight to potential source rock and reservoir rock distribution, maturation timing, migration pathways, and trap formation. Two data sets are used to illustrate such variations: both include a seismic reflection profile calibrated by multiple wells. The first is a Pennsylvanian mixed carbonate-siliciclastic system in the Paradox basin, and the second a Pliocene-Pleistocene siliciclastic system in the Gulf of Mexico. Numeric simulations result in geometry and facies distributions consistent with those interpreted using the integrated stratigraphic analysis of the calibrated seismic profiles. An exception occurs in the Gulf of Mexico study where the simulated sediment thickness from 3.8 to 1.6 Ma within an upper slope minibasin was less than that mapped using a regional seismic grid. Regional depositional patterns demonstrate that this extra thickness was probably sourced from out of the plane of the modeled transect, illustrating the necessity for three-dimensional constraints on two-dimensional modeling.

  5. Offshore Stratigraphic Controls on Salt-Water Intrusion in Los Angeles Area Coastal Aquifers

    NASA Astrophysics Data System (ADS)

    Edwards, B. D.; Ponti, D. J.; Ehman, K. D.; Tinsley, J. C.; Reichard, E. G.

    2002-12-01

    Ground water is a major component of the water supply for the ~10 million residents of Los Angeles County. Ground water pumping, linked to population growth since the early 1900's, caused water levels to decline, reversed seaward hydraulic gradients in some coastal aquifers, and resulted in salt water intrusion. United States Geological Survey geologists and hydrologists are working cooperatively with local water agencies to (1) understand and model the process of salt-water intrusion in this siliciclastic, structurally complex basin, and (2) identify potential pathways for the salt-water intrusion. We collected over 2000 trackline-km of single- and multi-channel intermediate- and high-resolution seismic-reflection profiles (60 to 5000 Hz) from the Los Angeles/Long Beach Harbor complex and the adjacent San Pedro shelf to develop a 3-dimensional stratigraphic model of the coastal aquifer system. These data define stratal geometries, paleo-channels, and fault traces in the offshore that are potential pathways of salt-water intrusion. The offshore seismic-reflection profiles correlate with onshore geophysical and borehole data collected from four nearby drill sites that were cored continuously to depths ranging to 400 meters. These core holes provide detailed 1-dimensional reference sections that furnish stratigraphic, age, and facies control for the seismic-reflection profiles. The coastal aquifer system is described using sequence stratigraphic concepts as units deposited during eustatic sea level fluctuations during the Pleistocene to Recent. Seismic-reflection profiles identify sequence boundaries, and hence aquifer and aquitard units, by the truncation and onlap of reflectors. If and where the sequences crop out on the sea floor provides a potential pathway for intrusion. The youngest unit, the Gaspur aquifer, is intruded with salt water and consists of at least two flat-lying sequences, each marked by basal gravelly sands deposited by the ancestral Los Angeles River as part of a broad channel complex. Salt water migrates up the Gaspur channel and into the underlying Gage aquifer that is comprised mostly of shallow marine and tidal sands, silts, and clays. Beneath the Gage, the Pleistocene San Pedro Formation consists of an aggradational set of marine-deltaic sands that thicken offshore and develop clinoform beds infilling the Palos Verdes basin. How these units are connected hydraulically controls the flow of salt water. We are incorporating the offshore seismic and onshore core data in a regional groundwater flow simulation model for the Los Angeles basin and in a transport model emphasizing salt-water intrusion.

  6. Structural and stratigraphic evolution of the East Georges Bank Basin, offshore Nova Scotia, Canada

    SciTech Connect

    Carswell, A.B. ); Koning, T. ); Hibbs, D.C. )

    1990-05-01

    The East Georges Bank Basin is located offshore Nova Scotia on the southeastern Canadian continental shelf. The basin covers 2.5 million ac and is one of the last undrilled basins in North America. The geological interpretation is almost entirely based on 16,000 km of seismic data over the basin. Pertinent well control is limited to 10 wells on the US portion of the Georges Bank (West Georges Bank Basin) and two wells on the Scotian shelf. Seismic-stratigraphic analysis of this data has led to a structural and stratigraphic model for the basin. The basin formed during the Triassic when the landmass of Pange began separating along rift zones. A prominent Paleozoic basement high, the Yarmouth Arch separated the East Georges Bank Basin from the West Georges Bank Basin and had a dominant influence on sedimentation until the Middle Jurassic. Early synrift sequences consist of lacustrine clastics and shales. Marine incursions began in the late Triassic resulting in massive salt deposits that reflect the restricted extent of the basin and the arid Triassic and Early Jurassic climate. Further continental separation during the Early Jurassic resulted in deposition of carbonates and evaporites followed by Middle Jurassic continental shelf carbonates and deltaic sands. During the Middle Jurassic, major growth faulting and halokinesis was initiated by progradation of the deltaic sands. Post Middle Jurassic continental spreading in combination with changing climatic conditions resulted in a steady decline of carbonate sedimentation and dominance of clastic deposition throughout the remaining history of the basin.

  7. Tectono-stratigraphic analysis of the Malvinas Basin, offshore the southernmost Argentinean continental margin

    NASA Astrophysics Data System (ADS)

    Baristeas, N.; Anka, Z.; di Primio, R.; Rodriguez, J. F.; Marchal, D.; Dominguez, F.

    2012-04-01

    A detailed tectono-stratigraphic analysis of the Malvinas Basin development, located offshore the Argentinean margin, was carried out. This was achieved through the interpretation of around 65,000 km of 2D seismic reflection profiles, spanning a dense grid on the shelf and the upper-slope of the basin. Five main seismo-stratigraphic units and their sub-units, informally named U1 to U5 a/b, bound by major unconformities were identified and correlated with the Mesozoic to Cenozoic main tectonic phases of the basin. U1 (Pre-168 Ma) represents the seismic basement and deepens gradually southwards. U2 (168-150.5 Ma, syn rift phase) fills regional depressions, onlapping the basement, and it thickens and deepens southwards. U1 and U2 are affected by several syn-rift normal faults, which have a main NE-SW strike direction in the south of the basin and a NW-SE strike direction in the centre of the basin. This suggests that the Malvinas Basin may have been developed initially as a rift basin with two different extensional directions. (1) a NW-SE directed extension probably linked with the opening of the Weddell Sea (Early Mid-Jurassic) and (2) a NE-SW directed extension most likely linked with the opening of the South Atlantic during Mid-Jurassic to Early Cretaceous. U3 (150.5-68 Ma, sag phase) is mainly an aggradational wedge-shaped unit. Some syn-rift faults continue into the Cretaceous. Sedimentation in this unit is mainly derived from the north and during Mid-Cretaceous also from the northeast, as documented by the presence of a southwestward prograding sedimentary fan located in the northeast of the basin. U4 (68-42.5 Ma, transtensional foredeep phase) overlies unconformly U3 and thickens to the south. Sediment input decreases dramatically during that time and only a thin sedimentary succession was deposited over the entire basin. Although a regional compressional regime is established from late Cretaceous to Cenozoic due to the Andean orogenesis, an extensional regime established in the Malvinas Basin during the Paleocene to early Eocene. This period was accompanied by the development of a deep sedimentary trough in the south. Extension was possibly related to the opening of the Drake Passage or to lithospheric flexure and bending. Structures mainly consist of reactivated normal faults, strike-slip faults and some minor reverse faults. The units U5a and U5b (42.5-5.5 and 5.5-0 Ma, transpressional foredeep phase) represent a stratigraphic switch from aggradation to progradation. While on the west of the basin downlapping clinoforms prograding eastwards are present, a northward onlapping wedge is identified in the deeper southern part of the basin. During this time, the sediment supply was considerably higher. The entire basin was filled and the depocenter migrated southeastwards. The tectonic regime changed to compression and later during the Oligocene to transpression, developing a major sinistral transpressional fault in the south of the basin. In summary, the basin developed initially as a Mesozoic rift basin which switches to a foreland basin with a sinistral wrench component and increased sediment input in the south during the Cenozoic.

  8. Revisiting the Tectono-Stratigraphic Evolution of the Eastern Mediterranean Offshore Levant and Nile Delta

    NASA Astrophysics Data System (ADS)

    Al-Balushi, Abdulaziz; Fraser, Alastair; A-L Jackson, Christopher; Bell, Rebecca; Kusznir, Nick

    2015-04-01

    Although the Eastern Mediterranean has become the focus for increased oil and gas exploration following significant discoveries in the pre-Messinian succession offshore Egypt and the Levant Margin, understanding its tectono-stratigraphic evolution is the first and most important step towards building reliable geological models that underpin petroleum play assessment. The Eastern Mediterranean Basin has evolved through a complex and poorly understood tectonic history. Disagreement within the scientific community relates to the age of rifting, the orientation of the crustal stretching direction and the type of crust underlying the Levant Basin and, by proxy, the magnitude of stretching. We present, for the first time, an interpretation of deep (i.e. 12-20 sec TWT) regional 2D seismic lines covering the entire Levant Basin. We have interpreted nine seismic surfaces (from top basement to seabed) from which depth and isopach maps for key surfaces and intervals have been generated. To constrain the rifting age, we have used a reverse subsidence modelling technique and restored the Middle Jurassic and the Late Cretaceous basin geometry along a NW-trending seismic profile from the Levant Basin. The restorations, for a specific rifting age, that meet geological constraints on water depth that are obtained from well data and seismic stratigraphy, are considered as viable solutions. The type of crust that underlies the Levant Margin has been inferred from the magnitude of the lithospheric stretching derived from gravity inversion and crustal thinning. Our interpretation of top basement and the Middle Jurassic depth-structure maps suggests that rifting in the Levant Basin led to the development of two main depocentres; in the northern Levant and the southern Levant, in the vicinity of the Nile Delta. These depocentres are separated by a series of NE-trending, fault- bound structural highs (i.e. Jonah and Leviathan). The orientation of the faults suggests they formed in response to NW-SE extension, which is further supported by the observation of a NW-SE-striking transform fault along the north-western Egyptian Margin. Reverse subsidence modelling indicates that rifting ages between 200 Ma and 176 Ma are required to restore the Middle Jurassic and the Upper Cretaceous surfaces to match the geological constraints on Middle Jurassic and Late Cretaceous palaeo-water depths. This predicted rifting age is in partial agreement with the rifting ages proposed by Gardosh et al. (2010) and Longacre et al. (2007) models. However, it disagrees with the rifting ages proposed by other models (i.e. Dercourt et al., 1986; Stampfli et al., 1991; Robertson, 1998; Garfunkel, 1998,2004). High values of lithospheric stretching (Beta > 5) are predicted by gravity inversion and crustal thinning in northern Levant which suggests that sea floor spreading is very likely to have occurred following rifting. We believe that a remnant of the Neo-Tethys Ocean is preserved because of the collision of the continental Eratosthenes Seamount with the Cyprus Arc, which locked up the subduction process.

  9. Coupled stratigraphic and structural evolution of a glaciated orogenic wedge, offshore St. Elias orogen, Alaska

    NASA Astrophysics Data System (ADS)

    Worthington, Lindsay L.; Gulick, Sean P. S.; Pavlis, Terry L.

    2010-12-01

    The St. Elias orogen is the result of ˜10 Myr of oblique convergence and flat-slab subduction in the Gulf of Alaska between North America and the Yakutat microplate. Extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge. Reflection seismic profiles across the offshore Pamplona zone fold-thrust belt, the frontal St. Elias orogenic wedge, provide constraints for quantifying Pleistocene deformation recorded in the glaciomarine Yakataga formation. The total amount of Pleistocene shortening observed varies from ˜3 to 5 mm/yr, compared to the current GPS-derived Yakutat-North America convergence rate across the St. Elias orogen of ˜45 mm/yr. Growth strata and kinematic fold analysis allow comparison of relative timing of fault activity, which reveals temporal and spatial shifting of active deformation during the glacial period: faulting localized adjacent to the coastline and at the current submarine deformation front. The abandoned, currently inactive region is colocated with the major glacial depocenter in the region, the Bering Trough. These observations imply that glacial processes such as sediment loading and focused erosion during advance-retreat cycles has a direct effect on the evolution of individual faults within the Pamplona zone and the overall deformation pattern in the offshore St. Elias margin. This information provides key constraints for understanding how climatic shifts may have affected the evolution of margin architecture during Pleistocene glacial-interglacial periods.

  10. The geostatistical approach for structural and stratigraphic framework analysis of offshore NW Bonaparte Basin, Australia

    NASA Astrophysics Data System (ADS)

    Wahid, Ali; Salim, Ahmed Mohamed Ahmed; Gaafar, Gamal Ragab; Yusoff, Wan Ismail Wan

    2016-02-01

    Geostatistics or statistical approach is based on the studies of temporal and spatial trend, which depend upon spatial relationships to model known information of variable(s) at unsampled locations. The statistical technique known as kriging was used for petrophycial and facies analysis, which help to assume spatial relationship to model the geological continuity between the known data and the unknown to produce a single best guess of the unknown. Kriging is also known as optimal interpolation technique, which facilitate to generate best linear unbiased estimation of each horizon. The idea is to construct a numerical model of the lithofacies and rock properties that honor available data and further integrate with interpreting seismic sections, techtonostratigraphy chart with sea level curve (short term) and regional tectonics of the study area to find the structural and stratigraphic growth history of the NW Bonaparte Basin. By using kriging technique the models were built which help to estimate different parameters like horizons, facies, and porosities in the study area. The variograms were used to determine for identification of spatial relationship between data which help to find the depositional history of the North West (NW) Bonaparte Basin.

  11. Sequence Stratigraphic Analysis for Delineating the Sedimentation Characteristic and Modeling of Nidoco Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El Deen, Ahmed; Abu El-Ata, Ahmed; El-Gendy, Nader

    2014-05-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for sequence stratigraphy using the different log tools for lithological interpretation and their impact upon the reflection characteristics and sequence stratigraphic interpretation, it is concluded the parasequence sets, system tracts, surface boundaries and their distribution within each well and their control on the sand distribution within each formation. In the present work, the Late Miocene (Messinian) and the Early Pliocene (Zanclian) pay-zones are the only rock units, that have integrated wireline logs approach, so it can be divided into 4 sequences; UM-1, UM-2A, UM-2B and LZ-1.

  12. The Role of Sequence Stratigraphic Analysis in the Messinian crisis at Baltim Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M.; Abu El-Ata, A. S.; El-Gendy, N. H.

    2013-12-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for sequence stratigraphy using the different log tools for lithological interpretation and their impact upon the reflection characteristics and sequence stratigraphic interpretation, it is concluded the parasequence sets, system tracts, surface boundaries and their distribution within each well and their control on the sand distribution within each formation. In the present work, the Late Miocene (Messinian) and the Early Pliocene (Zanclian) pay-zones are the only rock units, that have integrated wireline logs approach, so it can be divided into 4 sequences; UM-1, UM-2A, UM-2B and LZ-1.

  13. Stratigraphic and structural analysis of the Neogene sediments of the offshore portion of the Salina del Istmo Basin, southeastern Mexico

    NASA Astrophysics Data System (ADS)

    Gomez-Cabrera, Pedro Tomas

    2003-10-01

    Southeastern Mexico has been affected by regional and local tectonic events. Regional tectonic events are the Gulf of Mexico opening and the lateral movement of micro-plates on the Pacific margin. The local tectonic events are related to salt tectonics. Autochthonous Jurassic salt serves as the detachment level for the main compressional event in the late Miocene. Jurassic salt was allochthonously emplaced in the late Miocene, then partially displaced by a huge quantity of terrigenous sediments during the Plio-Pleistocene. This research is a study of the main geological processes that have influenced the structural and stratigraphic evolution of the Neogene sediments in the offshore portion of the Salina del Istmo basin known as the Marbella area. Owing to data availability, the project was divided into regional and local studies. The regional study is based on 2D multi-channel seismic reflection data, and the local study is based on a 3D seismic streamer survey. Structural analysis in the regional study permits the recognition of four buried fold belts (Agua Dulce, Catemaco, Marbella, and Marbella Norte) trending roughly NE. These fold belts are the result of tectonic convergence in the pacific margin during late Miocene. The Agua Dulce and Marbella Norte fold belts are separated by an enormous salt withdrawal basin called the Pescadores basin. The Pescadores basin is bounded on the north by a spectacular stepped, counter-regional structure. Beyond the Pescadores basin, a salt mini-basin area is recognized in the upper continental slope. Another important structural element is the Sal Somera canopy in the southern part of the study area. Sedimentation-rate analysis, based on isochore mapping in the local study area, indicates that from SB-2.4 to SB-2.6 Ma, deposition rate peaked with a maximum of 7.5 mm/yr. Regional and local structural restorations show that, in general, the maximum allochthonous salt mobilization was during the Plio-Pleistocene because of the huge quantity of sediments that the Chiapas massif and the Sierra de Chiapas supplied to the basin. A geohistory plot indicates rapid basin deepening at 2.4 to 2.6 Ma, which is attributed to a major influx of sediments and allochthonous salt evacuation.

  14. A preliminary guidebook for identifying stratigraphic contacts at the Nevada Test Site

    SciTech Connect

    Pawloski, G.A.; McKague, H.L.; Wagoner, J.L.; McKinnis, W.B.

    1992-01-01

    Lithologic variation, regional depositional trends, and the lack of written guidelines have resulted in inconsistencies in the recognition of stratigraphic contacts in drill holes at the Nevada Test Site (NTS). Stratigraphic identification, based on mineralogy of discrete samples, can be augmented by geophysical logs and downhole movies to more accurately and consistently locate contacts between units. Criteria are established for locating the base of the Pahute Mesa ash-flow tuff, the top of the Ammonia Tanks ash-flow tuff, the top of the Ammonia Tanks bedded tuff, and the top and the base of the Rainier Mesa Tuff.

  15. Selected stratigraphic data for drill holes located in Frenchman Flat, Nevada Test Site. Rev. 1

    SciTech Connect

    Drellack, S.L. Jr.

    1997-02-01

    Stratigraphic data are presented in tabular form for 72 holes drilled in Frenchman Flat, Nevada Test Site, between 1950 and 1993. Three pairs of data presentations are included for each hole: depth to formation tops, formation thicknesses, and formation elevations are presented in both field (English) and metric units. Also included for each hole, where available, are various construction data (hole depth, hole diameter, surface location coordinates) and certain information of hydrogeologic significance (depth to water level, top of zeolitization). The event name is given for holes associated with a particular nuclear test. An extensive set of footnotes is included, which indicates data sources and provides other information. The body of the report describes the stratigraphic setting of Frenchman Flat, gives drill-hole naming conventions and database terminology, and provides other background and reference material.

  16. New insights into the tectono-stratigraphic evolution of the Malvinas Basin, offshore of the southernmost Argentinean continental margin

    NASA Astrophysics Data System (ADS)

    Baristeas, N.; Anka, Z.; di Primio, R.; Rodriguez, J. F.; Marchal, D.; Dominguez, F.

    2013-09-01

    A detailed tectono-stratigraphic analysis of the Malvinas Basin was achieved by the interpretation of around 65,000 km of 2D seismic reflection profiles. Five main seismo-stratigraphic units and their sub-units, informally named units U1 to U5 a/b, bound by major unconformities were identified and correlated with the Mesozoic to Cenozoic main tectonic phases of the basin. Unit U1 (Pre-168 Ma) represents the seismic basement. Unit U2 (168-150.5 Ma, syn rift phase) thickens and deepens southwards. Units U1 and U2 are affected by several syn-rift normal faults that exhibit a main NE-SW strike direction in the south of the basin and a NW-SE strike direction in the centre of the basin. This suggests that the Malvinas Basin may have developed initially as a rift basin with two different extensional directions: (1) a NW-SE directed extension probably linked with the opening of the Weddell Sea (Early Mid-Jurassic), and (2) a NE-SW directed extension most likely linked with the Jurassic back-arc extension of Gondwana and probably later with the onset of the opening of the South Atlantic during Late Jurassic to Early Cretaceous time. Unit U3 (150.5-68 Ma, sag phase) is mainly an aggradational wedge-shaped unit. Unit U4 (68-42.5 Ma, transtensional foredeep phase) overlies unconformable unit U3. It deepens in the south because of an N-S/NW-SE directed extensional regime. Accumulation rates decrease during units U2, U3, and U4 from 4.84, to 1.23 to 0.8 km3/Ma 103. Units U5a and U5b (42.5-5.5 and 5.5-0 Ma, transpressional foredeep phase) finally represent a change from aggradation to progradation sedimentary pattern and to a left-lateral transpressional regime in the south. The sediment supply was considerably higher than before and a thick sedimentary wedge has been deposited until today. Accumulations rates increased in units U5a and U5b from 2.28 to 8.91 km3/Ma 103.

  17. Gas production from a cold, stratigraphically-bounded gas hydrate deposit at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Implications of uncertainties

    USGS Publications Warehouse

    Moridis, G.J.; Silpngarmlert, S.; Reagan, M.T.; Collett, T.; Zhang, K.

    2011-01-01

    As part of an effort to identify suitable targets for a planned long-term field test, we investigate by means of numerical simulation the gas production potential from unit D, a stratigraphically bounded (Class 3) permafrost-associated hydrate occurrence penetrated in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well on North Slope, Alaska. This shallow, low-pressure deposit has high porosities (?? = 0.4), high intrinsic permeabilities (k = 10-12 m2) and high hydrate saturations (SH = 0.65). It has a low temperature (T = 2.3-2.6 ??C) because of its proximity to the overlying permafrost. The simulation results indicate that vertical wells operating at a constant bottomhole pressure would produce at very low rates for a very long period. Horizontal wells increase gas production by almost two orders of magnitude, but production remains low. Sensitivity analysis indicates that the initial deposit temperature is by the far the most important factor determining production performance (and the most effective criterion for target selection) because it controls the sensible heat available to fuel dissociation. Thus, a 1 ??C increase in temperature is sufficient to increase the production rate by a factor of almost 8. Production also increases with a decreasing hydrate saturation (because of a larger effective permeability for a given k), and is favored (to a lesser extent) by anisotropy. ?? 2010.

  18. Thermometric well testing on the Vietnam offshore

    SciTech Connect

    San, T.N.; Shtyrlin, V.F.; Vakhitov, G.G.; Loi, L.M.; Listengarten, L.; Hien, D.L.

    1994-12-31

    It is impossible to control and adjust an oil and gas field development without determining the flow intervals of production wells. For that it is preferable to get production profiles by using the downhole flowmeter. There are, however, some main restrictions for wide-spread application of them on the offshore of Vietnam as follows: the flowmeter spinner velocity cannot indicate correctly in the open hole wells having a nonuniform diameter; it is unable to carry out in the case when the tubing shoe is lower than top formation on 300--500m. In this paper, the authors present a summary of temperature profile method to determine the flowing and intaking intervals of wells drilled in basement of the White Tiger Field on Vietnam offshore. For the last 2 years more than 30 wells were surveyed by this method in the above mentioned conditions. This paper presents the theory and practice of well temperature profile surveys, the concrete examples of data interpretation using the software Oiltest.

  19. Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Overview of scientific and technical program

    USGS Publications Warehouse

    Hunter, R.B.; Collett, T.S.; Boswell, R.; Anderson, B.J.; Digert, S.A.; Pospisil, G.; Baker, R.; Weeks, M.

    2011-01-01

    The Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled within the Alaska North Slope (ANS) Milne Point Unit (MPU) from February 3 to 19, 2007. The well was conducted as part of a Cooperative Research Agreement (CRA) project co-sponsored since 2001 by BP Exploration (Alaska), Inc. (BPXA) and the U.S. Department of Energy (DOE) in collaboration with the U.S. Geological Survey (USGS) to help determine whether ANS gas hydrate can become a technically and commercially viable gas resource. Early in the effort, regional reservoir characterization and reservoir simulation modeling studies indicated that up to 0.34 trillion cubic meters (tcm; 12 trillion cubic feet, tcf) gas may be technically recoverable from 0.92 tcm (33 tcf) gas-in-place within the Eileen gas hydrate accumulation near industry infrastructure within ANS MPU, Prudhoe Bay Unit (PBU), and Kuparuk River Unit (KRU) areas. To further constrain these estimates and to enable the selection of a test site for further data acquisition, the USGS reprocessed and interpreted MPU 3D seismic data provided by BPXA to delineate 14 prospects containing significant highly-saturated gas hydrate-bearing sand reservoirs. The "Mount Elbert" site was selected to drill a stratigraphic test well to acquire a full suite of wireline log, core, and formation pressure test data. Drilling results and data interpretation confirmed pre-drill predictions and thus increased confidence in both the prospect interpretation methods and in the wider ANS gas hydrate resource estimates. The interpreted data from the Mount Elbert well provide insight into and reduce uncertainty of key gas hydrate-bearing reservoir properties, enable further refinement and validation of the numerical simulation of the production potential of both MPU and broader ANS gas hydrate resources, and help determine viability of potential field sites for future extended term production testing. Drilling and data acquisition operations demonstrated that gas hydrate scientific research programs can be safely, effectively, and efficiently conducted within ANS infrastructure. The program success resulted in a technical team recommendation to project management to drill and complete a long-term production test within the area of existing ANS infrastructure. If approved by stakeholders, this long-term test would build on prior arctic research efforts to better constrain the potential gas rates and volumes that could be produced from gas hydrate-bearing sand reservoirs. ?? 2010 Elsevier Ltd.

  20. Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Torres, M.E.; Collett, T.S.; Rose, K.K.; Sample, J.C.; Agena, W.F.; Rosenbaum, E.J.

    2011-01-01

    The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (???100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20% of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores. ?? 2009 Elsevier Ltd.

  1. Geological and operational summary, Kodiak Shelf stratigraphic test wells, western Gulf of Alaska. Final report

    SciTech Connect

    Turner, R.F.; Lynch, M.B.; Conner, T.A.; Hallin, P.J.; Hoose, P.J.

    1987-10-01

    Contents include: regional petroleum exploration history; operational summary of the Kodiak Shelf stratigraphic drilling program; lithologic summary; velocity analysis; seismic stratigraphy and tectonic evolution of the Kodiak Shelf; well-log interpretation; biostratigraphy; organic geochemistry; geothermal gradient; abnormal formation pressure; shallow geology and geologic hazards; and environmental considerations.

  2. Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Coring operations, core sedimentology, and lithostratigraphy

    USGS Publications Warehouse

    Rose, K.; Boswell, R.; Collett, T.

    2011-01-01

    In February 2007, BP Exploration (Alaska), the U.S. Department of Energy, and the U.S. Geological Survey completed the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert well) in the Milne Point Unit on the Alaska North Slope. The program achieved its primary goals of validating the pre-drill estimates of gas hydrate occurrence and thickness based on 3-D seismic interpretations and wireline log correlations and collecting a comprehensive suite of logging, coring, and pressure testing data. The upper section of the Mount Elbert well was drilled through the base of ice-bearing permafrost to a casing point of 594??m (1950??ft), approximately 15??m (50??ft) above the top of the targeted reservoir interval. The lower portion of the well was continuously cored from 606??m (1987??ft) to 760??m (2494??ft) and drilled to a total depth of 914??m. Ice-bearing permafrost extends to a depth of roughly 536??m and the base of gas hydrate stability is interpreted to extend to a depth of 870??m. Coring through the targeted gas hydrate bearing reservoirs was completed using a wireline-retrievable system. The coring program achieved 85% recovery of 7.6??cm (3??in) diameter core through 154??m (504??ft) of the hole. An onsite team processed the cores, collecting and preserving approximately 250 sub-samples for analyses of pore water geochemistry, microbiology, gas chemistry, petrophysical analysis, and thermal and physical properties. Eleven samples were immediately transferred to either methane-charged pressure vessels or liquid nitrogen for future study of the preserved gas hydrate. Additional offsite sampling, analyses, and detailed description of the cores were also conducted. Based on this work, one lithostratigraphic unit with eight subunits was identified across the cored interval. Subunits II and Va comprise the majority of the reservoir facies and are dominantly very fine to fine, moderately sorted, quartz, feldspar, and lithic fragment-bearing to -rich sands. Lithostratigraphic and palynologic data indicate that this section is most likely early Eocene to late Paleocene in age. The examined units contain evidence for both marine and non-marine lithofacies, and indications that the depositional environment for the reservoir facies may have been shallower marine than originally interpreted based on pre-drill wireline log interpretations. There is also evidence of reduced salinity marine conditions during deposition that may be related to the paleo-climate and depositional conditions during the early Eocene. ?? 2010.

  3. Self-bored pressuremeter testing in the Arctic offshore

    SciTech Connect

    Hughes, J.M.O.; Jefferies, M.G.; Morris, D.L.

    1984-05-01

    Self-bored pressuremeter (SBP) tests are an important part of site investigations for gravity base structure (GBS) foundations. This applies in particular when such structures are expected to experience significant lateral loads, as most arctic structures are. The SBP data is used for both serviceability state analysis and for providing fundamental information on undisturbed soil behaviour. SBP testing has been carried out offshore for Gulf Canada Resources Inc. (GCRI) during the past two years (1982-1983 arctic open water seasons). Testing has been carried out in a variety of soil conditions across the GCRI land interest on the Canadian continental shelf in the Beaufort Sea. The paper outlines the equipment used, operational successes and difficulties, and presents productivity data. Techniques and equipment for improving productivity are outlined. Experience with SBP operations has shown that the SBP is no more difficult to use offshore than the electric static cone penetrometer (CPT). One result in particular of the SBP testing stands out; the in-situ geostatic stress ratio (K /SUB o/ ) has been found to be not a unique function of past overburden history. This result is discussed in the geological context. It appears prudent to regard K /SUB o/ as an independent variable for engineering purposes.

  4. Physical properties of sediment from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Winters, W.; Walker, M.; Hunter, R.; Collett, T.; Boswell, R.; Rose, K.; Waite, W.; Torres, M.; Patil, S.; Dandekar, A.

    2011-01-01

    This study characterizes cored and logged sedimentary strata from the February 2007 BP Exploration Alaska, Department of Energy, U.S. Geological Survey (BPXA-DOE-USGS) Mount Elbert Gas Hydrate Stratigraphic Test Well on the Alaska North Slope (ANS). The physical-properties program analyzed core samples recovered from the well, and in conjunction with downhole geophysical logs, produced an extensive dataset including grain size, water content, porosity, grain density, bulk density, permeability, X-ray diffraction (XRD) mineralogy, nuclear magnetic resonance (NMR), and petrography.This study documents the physical property interrelationships in the well and demonstrates their correlation with the occurrence of gas hydrate. Gas hydrate (GH) occurs in three unconsolidated, coarse silt to fine sand intervals within the Paleocene and Eocene beds of the Sagavanirktok Formation: Unit D-GH (614.4. m-627.9. m); unit C-GH1 (649.8. m-660.8. m); and unit C-GH2 (663.2. m-666.3. m). These intervals are overlain by fine to coarse silt intervals with greater clay content. A deeper interval (unit B) is similar lithologically to the gas-hydrate-bearing strata; however, it is water-saturated and contains no hydrate.In this system it appears that high sediment permeability (k) is critical to the formation of concentrated hydrate deposits. Intervals D-GH and C-GH1 have average "plug" intrinsic permeability to nitrogen values of 1700 mD and 675 mD, respectively. These values are in strong contrast with those of the overlying, gas-hydrate-free sediments, which have k values of 5.7. mD and 49 mD, respectively, and thus would have provided effective seals to trap free gas. The relation between permeability and porosity critically influences the occurrence of GH. For example, an average increase of 4% in porosity increases permeability by an order of magnitude, but the presence of a second fluid (e.g., methane from dissociating gas hydrate) in the reservoir reduces permeability by more than an order of magnitude. ?? 2010.

  5. Physical properties of sediment from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Winters, William J.; Walker, Michael; Hunter, Robert; Collett, Timothy S.; Boswell, Ray M.; Rose, Kelly K.; Waite, William F.; Torres, Marta; Patil, Shirish; Dandekar, Abhijit

    2011-01-01

    This study characterizes cored and logged sedimentary strata from the February 2007 BP Exploration Alaska, Department of Energy, U.S. Geological Survey (BPXA-DOE-USGS) Mount Elbert Gas Hydrate Stratigraphic Test Well on the Alaska North Slope (ANS). The physical-properties program analyzed core samples recovered from the well, and in conjunction with downhole geophysical logs, produced an extensive dataset including grain size, water content, porosity, grain density, bulk density, permeability, X-ray diffraction (XRD) mineralogy, nuclear magnetic resonance (NMR), and petrography. This study documents the physical property interrelationships in the well and demonstrates their correlation with the occurrence of gas hydrate. Gas hydrate (GH) occurs in three unconsolidated, coarse silt to fine sand intervals within the Paleocene and Eocene beds of the Sagavanirktok Formation: Unit D-GH (614.4 m-627.9 m); unit C-GH1 (649.8 m-660.8 m); and unit C-GH2 (663.2 m-666.3 m). These intervals are overlain by fine to coarse silt intervals with greater clay content. A deeper interval (unit B) is similar lithologically to the gas-hydrate-bearing strata; however, it is water-saturated and contains no hydrate. In this system it appears that high sediment permeability (k) is critical to the formation of concentrated hydrate deposits. Intervals D-GH and C-GH1 have average "plug" intrinsic permeability to nitrogen values of 1700 mD and 675 mD, respectively. These values are in strong contrast with those of the overlying, gas-hydrate-free sediments, which have k values of 5.7 mD and 49 mD, respectively, and thus would have provided effective seals to trap free gas. The relation between permeability and porosity critically influences the occurrence of GH. For example, an average increase of 4% in porosity increases permeability by an order of magnitude, but the presence of a second fluid (e.g., methane from dissociating gas hydrate) in the reservoir reduces permeability by more than an order of magnitude.

  6. Testing the impact of stratigraphic uncertainty on spectral analyses of sedimentary time series

    NASA Astrophysics Data System (ADS)

    Martinez, Mathieu; Kotov, Sergey; De Vleeschouwer, David; Pas, Damien; Vahlenkamp, Maximilian

    2015-04-01

    Spectral analysis has become a key tool for identifying the imprint of astronomical forcing on sedimentary records. In a next step, the identified cycles often contribute to the construction of a precise Geological Time Scale and to an in-depth understanding of past climate changes. Most of spectral analyses (Fast Fourier Transforms, the Multi-Taper Method) require a constant sample step. Unfortunately, an equally spaced geological data series is, in practice, nearly impossible to obtain from field sedimentary series. Usually, there is a 10% uncertainty on the field measurements of the stratigraphic thickness within sedimentary series. Hence, important uncertainties exist in the actual position of each sample. Another source of uncertainty are errors in a time-space model. In this study, we explore the impact that the stratigraphic uncertainty on the sample position has on the result of spectral analyses. To simulate this uncertainty, we developed a model based on Monte Carlo randomisation of the distance between each successive point. In this way, the stratigraphic order of the data points is not affected after implementing this model. The application of this model to a theoretical sinusoid series and to several real sedimentary series shows that uncertainties in the actual position of samples can highly reduce the spectral powers of the frequencies ranging from the Nyquist Frequency up to 1/10 of the Nyquist Frequency. We then demonstrate that the precise reconstruction of the Milankovitch cycles in the sedimentary record requires a higher sampling density than previously suggested with, at least, 10 samples per thinnest cycle to be detected, i.e. 10 samples per precession cycle.

  7. Offshore suspensions plume deposit as a stratigraphic signature of catastrophic river floods during the last 500 years: the case of the Amalfi coast

    NASA Astrophysics Data System (ADS)

    Molisso, Flavia; Esposito, Eliana; Porfido, Sabina; Sacchi, Marco; Violante, Crescenzo

    2010-05-01

    The Amalfi coast is a segment of the southern slope of the Sorrento Peninsula, a narrow and elevated mountain range (up to 1444 m) along the SW coastal zone of Italy. The Peninsula is deeply cut by a complex of bedrock rivers and channels characterized by relatively high energy of the relief, small catchment areas and pronounced disequilibrium of the stream profiles. There is evidence suggesting that the dynamic regime of the alluvial fans and associated fan-deltas of the Amalfi coast are controlled by episodic, but often catastrophic sediment and water discharges that have caused repeated flooding of the fans and accumulation of large volumes of sediment in the fan-deltas over last centuries. Documentary source materials show that, since the 16th century, at least 106 severe floods occurred over the Amalfi coast. The most dramatic episodes occurred between XVI and XX centuries (1581, 1588, 1773, 1899, 1954 events), caused severe geomorphologic change, damage to buildings and a high number of victims. The flood events triggered landslide, mud flow, debris flow and rock falls phenomena as well as denudation and erosion upstream. This research is based on the of stratigraphic study of marine gravity cores, and high-resolution seismic profiles acquired in the fan-delta deposits that develop at the mouth of the hydrographic system of the Amalfi coast. Particularly, the integrated stratigraphic analysis of prodelta deposits, shows that there is a consistent correlation between documental evidence of historical catastrophic floodings and the occurrence of individual layers or claster of (2-3 cm thick) layers of suspension deposit associated with sustained hyperpycnal plumes (underflows) within the fan-delta sequence. The identification of suspension plume deposits, within fan-delta deposits off the cliffed Amalfi coasts, may thus be regarded as a useful tool in order to explore the occurrence of major flooding episodes back to stratigraphic record of the Late Holocene.

  8. Automatic picking and attribute mapping for a quick evaluation of the potential of turbiditic sands and stratigraphic traps in frontier areas. An example from the deep offshore of the Niger Delta

    SciTech Connect

    Montagnier, P.; Rossi, T. ); Clergeat, B.; Dall'astam, W.F. )

    1996-01-01

    Most interpretation teams involved in the exploration of Nigeria's deep offshore have been faced with a major challenge: (1) how to scan through a large volume of 3D data in a drastically short time frame... (2) with the captive of understanding the depositional pattern of slope fan and basin floor fan turbidites to identify mostly stratigraphic traps... (3) in an environment almost devoid of reference wells and calibration. A traditional approach was likely to miss both the deadlines and the sensitivity required for the sedimentological aspects of the study. Elfs answer was to rely extensively on the advanced functionalities of the SISMAGE (TM) workstation, in order to quickly generate time and seismic attribute maps which could then be interpreted in terms of structure and sedimentology. Two critical aspects were particularly well handled by the workstation: (1) the reliability of the extrapolation process from a loose grid of manually picked lines, and (2) the generation of seismic attribute maps relative not only to surfaces (e.g. sequence boundaries), but also to whole intervals through statistical calculation. In a second stage, the interpreters were able to focus on the most prospective areas and to move on to prospect generation, with the help of AVO studies. This approach is illustrated through an example from the deep offshore of the Niger delta.

  9. Automatic picking and attribute mapping for a quick evaluation of the potential of turbiditic sands and stratigraphic traps in frontier areas. An example from the deep offshore of the Niger Delta

    SciTech Connect

    Montagnier, P.; Rossi, T.; Clergeat, B.; Dall`astam, W.F.

    1996-12-31

    Most interpretation teams involved in the exploration of Nigeria`s deep offshore have been faced with a major challenge: (1) how to scan through a large volume of 3D data in a drastically short time frame... (2) with the captive of understanding the depositional pattern of slope fan and basin floor fan turbidites to identify mostly stratigraphic traps... (3) in an environment almost devoid of reference wells and calibration. A traditional approach was likely to miss both the deadlines and the sensitivity required for the sedimentological aspects of the study. Elfs answer was to rely extensively on the advanced functionalities of the SISMAGE (TM) workstation, in order to quickly generate time and seismic attribute maps which could then be interpreted in terms of structure and sedimentology. Two critical aspects were particularly well handled by the workstation: (1) the reliability of the extrapolation process from a loose grid of manually picked lines, and (2) the generation of seismic attribute maps relative not only to surfaces (e.g. sequence boundaries), but also to whole intervals through statistical calculation. In a second stage, the interpreters were able to focus on the most prospective areas and to move on to prospect generation, with the help of AVO studies. This approach is illustrated through an example from the deep offshore of the Niger delta.

  10. Cenozoic synthem stratigraphic architecture of the SE Brazilian shelf and its global eustatic context: evidence from the Pelotas Basin (offshore Brazil)

    NASA Astrophysics Data System (ADS)

    de Santana dos Anjos Zerfass, Geise; Ruban, Dmitry A.; Chemale, Farid, Jr.; Zerfass, Henrique

    2013-12-01

    The Pelotas Basin, located on the SE Brazilian shelf, has evolved since the Aptian. Stratigraphical data from the basin can be used for delineation of the unconformity-bounded units (synthems) on the shelf, which is a first step towards a full understanding of its stratigraphic architecture, evolution, and hydrocarbon potential. Hiatuses in the Cenozoic succession of the Pelotas Basin are established with both biostratigraphic (planktonic foraminifers and calcareous nannofossils) and isotopic (87Sr/86Sr) data. The seven recognised hiatuses are dated respectively as (1) Palaeocene (Danian- Thanetian), (2) Palaeocene/Eocene boundary (Thanetian-Ypresian), (3) Eocene (Ypresian-Lutetian), (4) Eocene-Oligocene (Lutetian-Rupelian), (5) early-late Oligocene (Rupelian-Chattian), (6) early Miocene (Aquitanian-Burdigalian), and (7) middle-late Miocene (Serravallian-Tortonian). These intervals between the hiatuses are correlated with those of the Santos and Campos Basins north from the Pelotas Basin. The breaks in sedimentation that these basins have in common occurred (1) at the Palaeocene-Eocene and (2) Eocene-Oligocene transitions, (3) in the early Miocene, and (4) in the middle-late Miocene. These main unconformities outline five synthems on the SE Brazilian shelf, viz. the SEBS-1 (Palaeocene), SEBS-2 (Eocene), SEBS-3 (Oligocene), SEBS-4 (early-middle Miocene) and SEBS-5 (late Miocene-Holocene). The above unconformities are correlated with those established in the Cenozoic sedimentary successions of different regions such as Western Siberia, Arabia, NW and NE Africa, peninsular India, S Australia, the Gulf of Mexico, NW Europe, and South Africa. The only regional unconformity, near the Oligocene/Miocene boundary, coincides with the nearly-global sedimentation break. The latter was resulted from a climatic event, i.e., the `Mi-1 glaciation'. Thus, a eustatic origin is supposed for this regional unconformity. The other regional unconformities also correspond to global sea-level falls (probably with an exception for the Palaeocene/Eocene surface), which suggests that global eustatic movements controlled the development of the regional synthem architecture.

  11. Gas-Charged Sediments Within the Hyblean Plateu Seismo-Stratigraphic Sequence and Associated Likely Shallow Mud-Volacanoes Seafloor Features Offshore Southern Sicily (Sicily Channel - Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Savini, A.; Tessarolo, C.; Corselli, C.

    2007-12-01

    A shallow province of small-scale likely mud-volcanoes (MVs) seafloor features was recently discovered few miles offshore south-eastern Sicily (Holland et al., 2003) over the Hyblean-Malta plateau (Sicily-channel - Mediterranean sea), on an area whose surface might be over 100 square km and in a bathymetric range comprised between -100 and -200m. Such discovery promoted the National multidisciplinary programm MESC (Mud volcanoes Ecosystem study - Sicily Channel) aimed to provide a detailed acoustic mapping of the area (Savini et al., 2006) and focused water and sediment samples to study the ecosystem response to such geological phenomena. The main data set thus collected, during three different cruises carried out by the Italian R/V UNIVERSITATIS by mean of acoustic survey techniques, including new multibeam bathymetric data, side- scan sonar mosaics, a dense network of chirp-sonar profiles and focused multi-tip sparker profiles, is here presented. The detailed seafloor topography and the side scan sonar mosaic well show the occurrence of a field of more than 100 small scale conical and sub-conical seabed features, few meters high. Their morphologies, their strong acoustic scattering and the presence over them of distinct gas plumes, are foremost distinctive proprieties that liken them to MVs. Such filed consists of single and composite MVs arranged on the seafloor in two main different styles: 1) several conical features 50 - 200m in diameter, preferentially aligned along the isobaths 2) numerous close-set small cones no more than 10m in diameter, settled within well defined, flat, elongated areas (the largest one reaches 2000m in its long axis and 500m in its short axis) rising up to 10m from the seafloor. The acoustic character of the sediments in the chirp and sparker records indicates that such features are gas charged, because of the presence of numerous acoustic anomalies (i.e.: acoustic turbidity zones, wipe outs, gas pockets, enhanced reflectors...). In particular, the identified gas-related seafloor features are associated to sub- surface structures formed within a gas accumulative horizon covered by a variable thickness of sediments. This gas accumulative horizon has been found in association to a marked unconformity resembles the last trasgressive surface at the boundary between the Holocene and the Pleistocene sediments. Such gas-charged horizon has been used to map the depth of the free gas within the seafloor sediments. The depth of this "gas- front" is variable and domes up to the seafloor where MVs morphologies are found at the surface, often showing gas plumes (up to 20m high) at their top.

  12. Investigation of gas hydrate-bearing sandstone reservoirs at the "Mount Elbert" stratigraphic test well, Milne Point, Alaska

    SciTech Connect

    Boswell, R.M.; Hunter, R.; Collett, T.; Digert, S. Inc., Anchorage, AK); Hancock, S.; Weeks, M. Inc., Anchorage, AK); Mt. Elbert Science Team

    2008-01-01

    In February 2007, the U.S. Department of Energy, BP Exploration (Alaska), Inc., and the U.S. Geological Survey conducted an extensive data collection effort at the "Mount Elbert #1" gas hydrates stratigraphic test well on the Alaska North Slope (ANS). The 22-day field program acquired significant gas hydrate-bearing reservoir data, including a full suite of open-hole well logs, over 500 feet of continuous core, and open-hole formation pressure response tests. Hole conditions, and therefore log data quality, were excellent due largely to the use of chilled oil-based drilling fluids. The logging program confirmed the existence of approximately 30 m of gashydrate saturated, fine-grained sand reservoir. Gas hydrate saturations were observed to range from 60% to 75% largely as a function of reservoir quality. Continuous wire-line coring operations (the first conducted on the ANS) achieved 85% recovery through 153 meters of section, providing more than 250 subsamples for analysis. The "Mount Elbert" data collection program culminated with open-hole tests of reservoir flow and pressure responses, as well as gas and water sample collection, using Schlumberger's Modular Formation Dynamics Tester (MDT) wireline tool. Four such tests, ranging from six to twelve hours duration, were conducted. This field program demonstrated the ability to safely and efficiently conduct a research-level openhole data acquisition program in shallow, sub-permafrost sediments. The program also demonstrated the soundness of the program's pre-drill gas hydrate characterization methods and increased confidence in gas hydrate resource assessment methodologies for the ANS.

  13. FIELD TEST KIT FOR CHARACTERIZING OIL-BRINE EFFLUENTS FROM OFFSHORE DRILLING PLATFORMS

    EPA Science Inventory

    This research program was initiated to evaluate test methods for characterizing oil-brine effluents from offshore oil production platforms and to package and deliver a field test kit for on-site oil-brine analyses. After an initial laboratory evaluation and selection of test meth...

  14. Stratigraphic and palaeoenvironmental summary of the south-east Georgia Embayment: a correlation of exploratory wells

    USGS Publications Warehouse

    Poppe, L.J.; Popenoe, P.; Poag, C.W.; Swift, B.A.

    1995-01-01

    A Continental Offshore Stratigraphic Test (COST) well and six exploratory wells have been drilled in the south-east Georgia embayment. The oldest rocks penetrated are weakly metamorphosed Lower Ordovician quartz arenites and Silurian shales and argillites in the Transco 1005-1 well and Upper Devonian argillites in the COST GE-1 well. The Palaeozoic strata are unconformably overlain by interbedded non-marine Jurassic sandstones and shales and marginal marine Lower Cretaceous rocks. Together, these rocks are stratigraphically equivalent to the onshore Fort Pierce and Cotton Valley(?) Formations and rocks of the Lower Cretaceous Comanchean Provincial Series. The Upper Cretaceous part of the section is composed mainly of neritic calcareous shales and shaley limestones stratigraphically equivalent to the primarily marginal marine facies of the onshore Atkinson, Cape Fear and Middendorf Formations and Black Creek Group, and to limestones and shales of the Lawson Limestone and Peedee Formations. Cenozoic strata are also described. -from Authors

  15. Geophysical, stratigraphic, and flow-zone logs of selected test, monitor, and water-supply wells in Cayuga County, New York

    USGS Publications Warehouse

    Anderson, J. Alton; Williams, John H.; Eckhardt, David A. V.; Miller, Todd S.

    2003-01-01

    Volatile-organic compounds have been detected in water sampled from more than 50 supply wells between the City of Auburn and Village of Union Springs in Cayuga County, New York, and the area was declared a Superfund site in 2002. In 2001-04, geophysical logs were collected from 37 test, monitor, and water-supply wells as a preliminary part of the investigation of volatile-organic compound contamination in the carbonate-bedrock aquifer system. The geophysical logs included gamma, induction, caliper, wellbore image, deviation, fluid resistivity and temperature, and flowmeter. The geophysical logs were analyzed along with core samples and outcrops of the bedrock to define the stratigraphic units and flow zones penetrated by the wells. This report describes the logging methods used in the study and presents the geophysical, stratigraphic, and flow-zone logs.

  16. Offshore next generation weather radar (NEXRAD) test and evaluation master plan (TEMP)

    NASA Astrophysics Data System (ADS)

    Martinez, Radame; Cranston, Robert; Porcello, John

    1995-01-01

    This document provides the test philosophy and approach for the Offshore Next Generation Weather Radar (NEXRAD) Test and Evaluation Master Plan (TEMP). The NEXRAD differs from the typical Federal Aviation Administration (FAA) weather radar acquisition in that it is jointly funded by the Department of Defense (DOD), the Department of Commerce (DOC), and the Department of Transportation (DOT). These three agencies chartered the Joint System Program Office (JSPO) to manage the NEXRAD development and subsequent test programs. JSPO has deployed 70 single-channel radar systems across the continental United States (CONUS). The FAA is deploying NEXRAD systems at non-CONUS (offshore) locations such as Alaska, Hawaii, and the Caribbean. The FAA Offshore NEXRAD will have a redundant configuration and a Remote Monitoring Subsystem (EMS). A total of 14 Offshore NEXRAD's will be procured under this acquisition: 3 in the Caribbean, 4 in Hawaii, and 7 in Alaska. Funding constraints will limit the acquisition to seven NEXRAD's in the 1994-1995 timeframe.

  17. Formation pressure testing at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Operational summary, history matching, and interpretations

    USGS Publications Warehouse

    Anderson, B.; Hancock, S.; Wilson, S.; Enger, C.; Collett, T.; Boswell, R.; Hunter, R.

    2011-01-01

    In February 2007, the U.S. Department of Energy, BP Exploration (Alaska), and the U.S. Geological Survey, collected open-hole pressure-response data, as well as gas and water sample collection, in a gas hydrate reservoir (the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well) using Schlumberger's Modular Dynamics Formation Tester (MDT) wireline tool. Four such MDT tests, ranging from six to twelve hours duration, and including a series of flow, sampling, and shut-in periods of various durations, were conducted. Locations for the testing were selected based on NMR and other log data to assure sufficient isolation from reservoir boundaries and zones of excess free water. Test stages in which pressure was reduced sufficiently to mobilize free water in the formation (yet not cause gas hydrate dissociation) produced readily interpretable pressure build-up profiles. Build-ups following larger drawdowns consistently showed gas-hydrate dissociation and gas release (as confirmed by optical fluid analyzer data), as well as progressive dampening of reservoir pressure build-up during sequential tests at a given MDT test station.History matches of one multi-stage, 12-h test (the C2 test) were accomplished using five different reservoir simulators: CMG-STARS, HydrateResSim, MH21-HYDRES, STOMP-HYD, and TOUGH. +. HYDRATE. Simulations utilized detailed information collected across the reservoir either obtained or determined from geophysical well logs, including thickness (11.3. m, 37 ft.), porosity (35%), hydrate saturation (65%), both mobile and immobile water saturations, intrinsic permeability (1000 mD), pore water salinity (5 ppt), and formation temperature (3.3-3.9 ??C). This paper will present the approach and preliminary results of the history-matching efforts, including estimates of initial formation permeability and analyses of the various unique features exhibited by the MDT results. ?? 2010 Elsevier Ltd.

  18. Development of LiDAR measurements for the German offshore test site

    NASA Astrophysics Data System (ADS)

    Rettenmeier, A.; Khn, M.; Wchter, M.; Rahm, S.; Mellinghoff, H.; Siegmeier, B.; Reeder, L.

    2008-05-01

    The paper introduces the content of the recently started joint research project 'Development of LiDAR measurements for the German Offshore Test Site' which has the objective to support other research projects at the German offshore test site 'alpha ventus'. The project has started before the erection of the offshore wind farm and one aim is to give recommendations concerning LiDAR technology useable for offshore measurement campaigns and data analysis. The work is organized in four work packages. The work package LiDAR technology deals with the specification, acquisition and calibration of a commercial LiDAR system for the measurement campaigns. Power curve measurements are dedicated to power curve assessment with ground-based LiDAR using standard statistical methods. Additionally, it deals with the development of new methods for the measurement of non-steady short-term power curves. Wind field research aims at the development of wake loading simulation methods of wind turbines and the exploration of loading control strategies and nacelle-based wind field measurement techniques. Finally, dissemination of results to the industry takes place in work package Technology transfer.

  19. Extensional tectonics, halokinesis, eustacy in the Norwegian Central Graben, North Sea: A testing ground for sequence and seismic stratigraphic principles

    SciTech Connect

    Spencer, P.A.; Prosser, S.D.

    1996-12-31

    The Norwegian Central Graben is a mature hydrocarbon province with proven reserves within the Upper Jurassic succession. Several phases of extensional tectonics ranging from the Permo-Triassic to the Upper Jurassic, and a thick mobile salt section, serve to complicate a clear regional understanding of the area. A full integration of structural interpretation, seismic and sequence stratigraphic principles, biostratigraphy and core studies is required to achieve a realistic interpretation and predict Upper Jurassic facies distributions within this complex area. Utilizing some 30 wells, regional seismic data and biostratigraphy, candidate sequence boundaries and regionally correlatable flooding surfaces (e.g. Eudoxus), have been identified. Horizon flattening on these surfaces has allowed the recognition of thickening-away reflection geometries adjacent to salt features and divergent geometries into graben boundary faults. This facilitates the identification of the dominant local or regional controls on accommodation space creation. Detailed seismic facies analysis was then used to reveal the relative expansion or suppression of depositional systems tracts as a response to either regional or local structural controls. It was subsequently possible to place these systems within a biostratigraphically constrained regional framework. Mapping the base Zechstein, base Jurassic and base Cretaceous horizons has provided a map view of the active faults and slopes controlling sediment transport at any given time. This provided the third dimension essential in depicting the spatial distribution of depositional systems, and is a crucial component of any sequence stratigraphic interpretation. A regional picture of the progressive evolution of this complex area has been thus been derived, and the effect of both regional and local controls on sequence stratigraphic expressions has been determined.

  20. Extensional tectonics, halokinesis, eustacy in the Norwegian Central Graben, North Sea: A testing ground for sequence and seismic stratigraphic principles

    SciTech Connect

    Spencer, P.A. ); Prosser, S.D. )

    1996-01-01

    The Norwegian Central Graben is a mature hydrocarbon province with proven reserves within the Upper Jurassic succession. Several phases of extensional tectonics ranging from the Permo-Triassic to the Upper Jurassic, and a thick mobile salt section, serve to complicate a clear regional understanding of the area. A full integration of structural interpretation, seismic and sequence stratigraphic principles, biostratigraphy and core studies is required to achieve a realistic interpretation and predict Upper Jurassic facies distributions within this complex area. Utilizing some 30 wells, regional seismic data and biostratigraphy, candidate sequence boundaries and regionally correlatable flooding surfaces (e.g. Eudoxus), have been identified. Horizon flattening on these surfaces has allowed the recognition of thickening-away reflection geometries adjacent to salt features and divergent geometries into graben boundary faults. This facilitates the identification of the dominant local or regional controls on accommodation space creation. Detailed seismic facies analysis was then used to reveal the relative expansion or suppression of depositional systems tracts as a response to either regional or local structural controls. It was subsequently possible to place these systems within a biostratigraphically constrained regional framework. Mapping the base Zechstein, base Jurassic and base Cretaceous horizons has provided a map view of the active faults and slopes controlling sediment transport at any given time. This provided the third dimension essential in depicting the spatial distribution of depositional systems, and is a crucial component of any sequence stratigraphic interpretation. A regional picture of the progressive evolution of this complex area has been thus been derived, and the effect of both regional and local controls on sequence stratigraphic expressions has been determined.

  1. Grid Simulator for Testing a Wind Turbine on Offshore Floating Platform

    SciTech Connect

    Gevorgian, V.

    2012-02-01

    An important aspect of such offshore testing of a wind turbine floating platform is electrical loading of the wind turbine generator. An option of interconnecting the floating wind turbine with the onshore grid via submarine power cable is limited by many factors such as costs and associated environmental aspects (i.e., an expensive and lengthy sea floor study is needed for cable routing, burial, etc). It appears to be a more cost effective solution to implement a standalone grid simulator on a floating platform itself for electrical loading of the test wind turbine. Such a grid simulator must create a stable fault-resilient voltage and frequency bus (a micro grid) for continuous operation of the test wind turbine. In this report, several electrical topologies for an offshore grid simulator were analyzed and modeled.

  2. Model test of new floating offshore wind turbine platforms

    NASA Astrophysics Data System (ADS)

    Shin, Hyunkyoung; Dam, Pham Thanh; Jung, Kwang Jin; Song, inseob; Rim, Chaewhan; Chung, Taeyoung

    2013-06-01

    This paper presents the model test results of 3 new spar platforms which were developed based on the OC3-Hywind spar to support a 5-MW wind turbine. By changing the shape but keeping both volume and mass of OC3- Hywind spar platform, those platforms were expected to experience different hydrodynamic and hydrostatic loads. The scale models were built with a 1/128 scale ratio. The model tests were carried out in waves, including both rotating rotor effect and mean wind speed. The characteristic motions of the 3 new models were measured; Response Amplitude Operators (RAO) and significant motions were calculated and compared with those of OC3-Hywind.

  3. Development and testing of new offshore cathodic protection criteria

    SciTech Connect

    Evans, S.

    1986-05-01

    New sacrificial anode protection criteria developed and tested by Dubai Petroleum Co. (DPC) resulted in a 40% decrease in anode weight as compared to that required by conventionally accepted design. Derivation of the criteria is based on an analysis of extensive field results of potential surveys of seven DPC platforms that had conventional sacrificial anode protection systems. It was found that an initial platform current density of 29+.2 x 10/sup -3/A/sq ft (310+.20mA/m/sup 2/) of area exposed to seawater resulted in polarization of the platform to -1 V with respect to the silver/silver-chloride reference electrode. As a consequence of this initial polarization, the electric current requirement for protection is reduced significantly. The new criteria were used in the design of Platform JJ, which was installed in September 1982. Field results that include periodic potential surveys of Platform JJ are presented and discussed.

  4. Sentinel Hill Core Test 1: Facies Descriptions and Stratigraphic Reinterpretations of the Prince Creek and Schrader Bluff Formations, North Slope, Alaska

    USGS Publications Warehouse

    Flores, Romeo M.; Stricker, Gary D.; Decker, Paul L.; Myers, Mark D.

    2007-01-01

    The Sentinel Hill Core Test 1 well penetrated an intertonguing sequence of (1) the marine Schrader Bluff Formation in the depth intervals 950?1,180 ft and 690?751 ft, which consists of shoreface and offshore deposits that accumulated along a storm-dominated, barred shoreline; and (2) the nonmarine Prince Creek Formation in the depth intervals 751?950 ft and surface to 690 ft, which consists of fluvial channel, crevasse splay, backswamp, and ash fall deposits. The strata range in age from early Campanian to early Maastrichtian. An erosional contact at a depth of 690 ft at the base of the upper unit of the Prince Creek Formation is interpreted as a major regional sequence boundary, and the overlying conglomeratic fluvial channel deposits are interpreted to have accumulated in a paleovalley. In its more proximal reaches along the Colville River, channels of this paleovalley cut down 75 ft into the lowermost Prince Creek Formation and the uppermost Schrader Bluff Formation. Farther offshore, the equivalent surface to the aforementioned paleovalley appears to be a subtle discontinuity between middle and lower Schrader Bluff Formation shelfal marine strata. Still farther offshore, the equivalent paleovalley surface is interpreted as a marine mass-wasting surface that locally cuts through the lowermost Schrader Bluff Formation and into the underlying Seabee Formation.

  5. Regional long-term production modeling from a single well test, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    SciTech Connect

    Anderson, Brian; Kurihara, Masanori; White, Mark D.; Moridis, George J.; Wilson, Scott J.; Pooladi-Darvish, Mehran; Gaddipati, Manohar; Masuda, Yoshihiro; Collett, T. S.; Hunter, Robert B.; Narita, Hideo; Rose, Kelly K.; Boswell, Ray

    2011-02-02

    Following the results from the open-hole formation pressure response test in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert well) using Schlumbergers Modular Dynamics Formation Tester (MDT) wireline tool, the International Methane Hydrate Reservoir Simulator Code Comparison project performed long-term reservoir simulations on three different model reservoirs. These descriptions were based on 1) the Mount Elbert gas hydrate accumulation as delineated by an extensive history-matching exercise, 2) an estimation of the hydrate accumulation near the Prudhoe Bay L-pad, and 3) a reservoir that would be down-dip of the Prudhoe Bay L-pad and therefore warmer and deeper. All of these simulations were based, in part, on the results of the MDT results from the Mount Elbert Well. The comparison groups consensus value for the initial perme- ability of the hydrate-filled reservoir (k = 0.12 mD) and the permeability model based on the MDT history match were used as the basis for subsequent simulations on the three regional scenarios. The simulation results of the five different simulation codes, CMG STARS, HydrateResSim, MH-21 HYDRES, STOMP-HYD, and TOUGHHYDRATE exhibit good qualitative agreement and the variability of potential methane production rates from gas hydrate reservoirs is illustrated. As expected, the pre- dicted methane production rate increased with increasing in situ reservoir temperature; however, a significant delay in the onset of rapid hydrate dissociation is observed for a cold, homogeneous reservoir and it is found to be repeatable. The inclusion of reservoir heterogeneity in the description of this cold reservoir is shown to eliminate this delayed production. Overall, simulations utilized detailed information collected across the Mount Elbert reservoir either obtained or determined from geophysical well logs, including thickness (37 ft), porosity (35%), hydrate saturation (65%), intrinsic permeability (1000 mD), pore water salinity (5 ppt), and formation temperature (3.33.9 ?C). This paper presents the approach and results of extrapolating regional forward production modeling from history-matching efforts on the results from a single well test.

  6. Regional long-term production modeling from a single well test, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Anderson, B.J.; Kurihara, M.; White, M.D.; Moridis, G.J.; Wilson, S.J.; Pooladi-Darvish, M.; Gaddipati, M.; Masuda, Y.; Collett, T.S.; Hunter, R.B.; Narita, H.; Rose, K.; Boswell, R.

    2011-01-01

    Following the results from the open-hole formation pressure response test in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert well) using Schlumberger's Modular Dynamics Formation Tester (MDT) wireline tool, the International Methane Hydrate Reservoir Simulator Code Comparison project performed long-term reservoir simulations on three different model reservoirs. These descriptions were based on 1) the Mount Elbert gas hydrate accumulation as delineated by an extensive history-matching exercise, 2) an estimation of the hydrate accumulation near the Prudhoe Bay L-pad, and 3) a reservoir that would be down-dip of the Prudhoe Bay L-pad and therefore warmer and deeper. All of these simulations were based, in part, on the results of the MDT results from the Mount Elbert Well. The comparison group's consensus value for the initial permeability of the hydrate-filled reservoir (k = 0.12 mD) and the permeability model based on the MDT history match were used as the basis for subsequent simulations on the three regional scenarios. The simulation results of the five different simulation codes, CMG STARS, HydrateResSim, MH-21 HYDRES, STOMP-HYD, and TOUGH+HYDRATE exhibit good qualitative agreement and the variability of potential methane production rates from gas hydrate reservoirs is illustrated. As expected, the predicted methane production rate increased with increasing in situ reservoir temperature; however, a significant delay in the onset of rapid hydrate dissociation is observed for a cold, homogeneous reservoir and it is found to be repeatable. The inclusion of reservoir heterogeneity in the description of this cold reservoir is shown to eliminate this delayed production. Overall, simulations utilized detailed information collected across the Mount Elbert reservoir either obtained or determined from geophysical well logs, including thickness (37 ft), porosity (35%), hydrate saturation (65%), intrinsic permeability (1000 mD), pore water salinity (5 ppt), and formation temperature (3.3-3.9 ??C). This paper presents the approach and results of extrapolating regional forward production modeling from history-matching efforts on the results from a single well test. ?? 2010 Elsevier Ltd.

  7. Shaking table test and numerical analysis of offshore wind turbine tower systems controlled by TLCD

    NASA Astrophysics Data System (ADS)

    Chen, Jianbing; Liu, Youkun; Bai, Xueyuan

    2015-03-01

    A wind turbine system equipped with a tuned liquid column damper (TLCD) is comprehensively studied via shaking table tests using a 1/13-scaled model. The effects of wind and wave actions are considered by inputting response-equivalent accelerations on the shaking table. The test results show that the control effect of the TLCD system is significant in reducing the responses under both wind-wave equivalent loads and ground motions, but obviously varies for different inputs. Further, a blade-hub-tower integrated numerical model for the wind turbine system is established. The model is capable of considering the rotational effect of blades by combining Kane's equation with the finite element method. The responses of the wind tower equipped with TLCD devices are numerically obtained and compared to the test results, showing that under both controlled and uncontrolled conditions with and without blades' rotation, the corresponding responses exhibit good agreement. This demonstrates that the proposed numerical model performs well in capturing the wind-wave coupled response of the offshore wind turbine systems under control. Both numerical and experimental results show that the TLCD system can significantly reduce the structural response and thus improve the safety and serviceability of the offshore wind turbine tower systems. Additional issues that require further study are discussed.

  8. Stratigraphic traps 1

    SciTech Connect

    Beaumont, E.A.; Foster, N.H.

    1990-01-01

    A spectrum of trap types exists. On one end of this spectrum are traps that exist only because of stratigraphic elements. On the other end of the spectrum are traps that exist only because of structural elements. Pure structural traps are not as common as one might suppose. In a pure structural trap the hydrocarbon/water contact parallels the structure contours completely around the trap. A majority of traps have an element of lateral stratigraphic control: they exist due to a combination of structure and stratigraphy. In these traps the hydrocarbon/water contact does not parallel the structure contours. This book contains studies of fields that have traps that are either purely stratigraphic or that combine stratigraphic and structural elements. In this volume, traps that are nearly pure stratigraphic traps include those of Albion-Scipio (Michigan basin), Kasim and Walio (Salawati basin), Jameson (Permian basin), Frigg (North Sea basin), Berlin (Anadarko basin), and Hoadley (Alberta basin). The trap of albion-Scipio field resulted from development of porosity due to dolomitization of a limestone along a preexisting strike-slip fault system.

  9. Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design

    PubMed Central

    Matha, Denis; Sandner, Frank; Molins, Climent; Campos, Alexis; Cheng, Po Wen

    2015-01-01

    The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms. PMID:25583870

  10. Efficient preliminary floating offshore wind turbine design and testing methodologies and application to a concrete spar design.

    PubMed

    Matha, Denis; Sandner, Frank; Molins, Climent; Campos, Alexis; Cheng, Po Wen

    2015-02-28

    The current key challenge in the floating offshore wind turbine industry and research is on designing economic floating systems that can compete with fixed-bottom offshore turbines in terms of levelized cost of energy. The preliminary platform design, as well as early experimental design assessments, are critical elements in the overall design process. In this contribution, a brief review of current floating offshore wind turbine platform pre-design and scaled testing methodologies is provided, with a focus on their ability to accommodate the coupled dynamic behaviour of floating offshore wind systems. The exemplary design and testing methodology for a monolithic concrete spar platform as performed within the European KIC AFOSP project is presented. Results from the experimental tests compared to numerical simulations are presented and analysed and show very good agreement for relevant basic dynamic platform properties. Extreme and fatigue loads and cost analysis of the AFOSP system confirm the viability of the presented design process. In summary, the exemplary application of the reduced design and testing methodology for AFOSP confirms that it represents a viable procedure during pre-design of floating offshore wind turbine platforms. PMID:25583870

  11. Stratigraphic traps 2

    SciTech Connect

    Not Available

    1991-01-01

    This volume contains studies of fields with traps that are mainly stratigraphic in nature. Structure plays a role in the traps of several fields, but overall, it is clear that the main trapping features with the group of fields in this volume are stratigraphic. The first six fields in this volume, Alabama Ferry, Rospo Mare, Walker Creek, Bindley, Lexington, and Newburg/South Westhope, have carbonate reservoirs. The latter two of these, Lexington and Newburg/South Westhope, also have sandstone reservoirs. The remaining fields, East Texas, East Clinton, Stockholm Southwest, Sorrento, Port Acres, and Lagoa Parda, have only sandstone reservoirs.

  12. Teaching with Stratigraphic Profiles

    ERIC Educational Resources Information Center

    Stefanich, Greg P.

    1974-01-01

    Presents two exercises modeled after the ice age puzzle described in the ESCP textbook, including formation of terminal moraines and kettle lakes and intersection of normal faults with gold-quartz veins. Indicates that the stratigraphic profiles are usable in teaching earth science, geography, general science, and topographic problems. (CC)

  13. Brief: Offshore North Sea case histories of the environmentally friendly testing vessel, the Crystal Sea

    SciTech Connect

    Tjelta, O.; Ashwell, C.; Hilmarsen, G.; Taylor, R.W.

    1996-04-01

    One problem during offshore well-test operations, stimulations, and routine workovers are discharges into the air and sea while flaring. These procedures are usually performed by mobile drilling rigs with no storage capacity, and thus, hydrocarbons sequestered must be burned off from the rig flare booms. Another major problem has been the inability of the flare to operate at high flow rates. Because the burning process slows the pace of a test, restricting full flow testing, valuable well information is lost. Flaring of hydrocarbons also represents an economic loss. In the case of oil rigs, for example, flaring not only emits CO{sub 2} into the atmosphere but also burns off usable oil. The Crystal Sea well-test vessel was designed to address the problems inherent to flaring and, at the same time, provide cost efficiency by salvaging usable oil during well testing. The success of her initial two jobs on the Statfjord North satellite field in the Norwegian sector of the North Sea confirms that sale of the salvaged oil normally lost during the flaring process could generate sufficient economic return to pay for the vessel. In addition, with its capability to receive products at twice the flow rate of conventional methods, the increased accuracy of the technical information obtained from the well test further enhances its value for improved reservoir management.

  14. Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Stern, L.A.; Lorenson, T.D.; Pinkston, J.C.

    2011-01-01

    Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5. m to 760.1. m depth, and sections investigated here were retrieved from 619.9. m and 661.0. m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70-75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20-120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas. ?? 2009.

  15. Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Stern, Laura A.; Lorenson, T.D.; Pinkston, John C.

    2011-01-01

    Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXADOEUSGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5 m to 760.1 m depth, and sections investigated here were retrieved from 619.9 m and 661.0 m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 7075% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas.

  16. Case study of preliminary cyclic load evaluation and triaxial soil testing in offshore wind farm planning

    NASA Astrophysics Data System (ADS)

    Otto, Daniel; Ossig, Benjamin; Kreiter, Stefan; Kouery, Saed; Moerz, Tobias

    2010-05-01

    In 2020 Germany aims to produce 20% of its electrical power trough renewable energy sources. Assigned Offshore Wind farms in the German exclusive economic zone of the North- and the Baltic Sea are important step toward a fulfilment of this goal. However the save erecting of 5-6 MW wind power plants (total construction size: > 200m) in water depth of around 40 m is related to unprecedented technical, logistical and financial challenges. With an intended lifetime expectation of 50 years for the foundations, construction materials and the soils around the foundation are subject to high and continued stresses from self-weight, waves, wind and current. These stresses are not only static, but have also a significant cyclic component. An estimated 250 million cyclic load changes may lead to an accumulation of plastic deformation in the soil that potentially may affect operability or lifespan of the plant. During a preliminary geotechnical site survey of one of the largest (~150 km2) offshore wind project sites within the German Bight (~45 km North off the island Juist) a total of 16 drill cores with in situ cone penetration data and a total sample length of ~800 m where recovered. Preliminary foundation designs and static self weight and lateral load calculations were used to design a cycling triaxial lab testing program on discrete natural soil samples. Individual tests were performed by foundation type and at vertical and lateral load maxima to evaluate the long-term soil behaviour under cyclic load. Tests have been performed on granular, cohesive and intermediate natural soils. Following an introduction to the unique MARUM triaxial apparatus and testing conditions, the cyclic triaxial test results are shown and explained. Furthermore cyclic shear strength and stiffness are compared to their static counterparts. Unique soil behaviour like abrupt partial failure, pore pressure response and unexpected in part load independent cyclic deformation behaviour is discussed and compared to literature results. The shown case study is intended to demonstrate a feasible procedure for evaluating cyclic loads, designing test procedures, presenting results and interpreting data in a so far unregulated field without common standards. The presented data has been produced within the framework of germanwind, a science industry partnership including RWE-Innogy, ENOVA and MARUM.

  17. Offshore northern sea case histories of the environmentally friendly testing vessel, the ``Crystal Sea``

    SciTech Connect

    Tjelta, O.; Ashwell, C.; Hilmarsen, G.; Taylor, R.W.

    1995-12-01

    One of the problems that surfaces during offshore well test operations, stimulations, and routine workovers has been the discharges that are made into the air and sea, and in particular, the possible formation of dioxins during the combustion process. Since these operations and tests have normally been performed by mobile drilling rigs that do not have storage capacity, oil and gas sequestered during performance of the procedures are burned off from the rig flarebooms. Another major problem during well testing has been the incapability of the flare to operate at high flow rates. Since the burning process slows down the pace of a test and does not allow the well to be tested under full flow, valuable information about the well cannot be determined. In light of the economic and regulatory changes occurring in today`s oil and gas industry, the justification for development of a cost-effective, environmentally-safe alternative to flaring hydrocarbons was certainly indicated. This paper will discuss the well test vessel, ``Crystal Sea,`` and the initial two jobs on the Statfjord North Satellite Field in the Norwegian sector of the North Sea. The success of these jobs confirms that the Crystal Sea can provide an alternative to flaring that reduces the degree of pollutants discharged from oil rigs, and at the same time, can salvage the usable oil. The sale of the salvaged oil, which would normally be lost during the flaring process, often can generate sufficient economic return to pay for the vessel. ``Crystal Sea`` is capable of receiving products at approximately twice the flow rate as is possible with conventional surface test equipment from a rig. This increased flow rate not only improves the accuracy of the technical information obtained from the well test but also provides valuable tools for improved reservoir management.

  18. Relative sensitivity of one freshwater and two marine acute toxicity tests as determined by testing 30 offshore E & P chemicals.

    PubMed

    Sverdrup, Line E; Fürst, Charlotte S; Weideborg, Mona; Vik, Eilen A; Stenersen, Jørgen

    2002-01-01

    Acute toxicity of 30 offshore E & P (Exploration and Production) chemicals was measured using the three standard test organisms Daphnia magna (freshwater cladoceran), Acartia tonsa (marine copepod) and Skeletonema costatum (marine diatom alga). Test chemicals included 20 water-soluble and 10 (partially) non-soluble products. For 22 out of the 30 chemicals, the difference in sensitivity between the three tests varied within one order of magnitude. A very good correlation was found between the two marine tests (r = 0.96, P < 0.01, n = 30), and a correlation coefficient of r = 0.78 (P < 0.01, n = 30) was found between D. magna and both A. tonsa and S. costatum, individually. When the comparison of D. magna and A. tonsa sensitivity was based only on the water-soluble chemicals, a significantly higher correlation was obtained (r = 0.84, n = 20), indicating that the sample preparation method used for the (partially) non-soluble chemicals (the water accommodated fraction (WAF) method) induces additional variation between tests performed with different test media. (Partially) non-soluble chemicals are characterised by phase separation or precipitation at the concentrations used for testing. In a WAF-based test, each test concentration/exposure level is prepared separately, and following mixing and separation, only the water phase is used for testing. Toxicity is related to the amount of substance originally added to the mixing vessels. For 25 of the 30 chemicals, D. magna was found to be less sensitive than the marine copepod by a factor >2. The generally higher sensitivity of the marine toxicity tests compared to the Daphnia test emphasise the importance of using marine data for environmental hazard classification as well as for environmental risk assessment purposes. PMID:11827290

  19. High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    USGS Publications Warehouse

    Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

    2011-01-01

    A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

  20. Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

    USGS Publications Warehouse

    Kneafsey, T.J.; Lu, H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

    2011-01-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  1. Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

    SciTech Connect

    Kneafsey, T.J.; Liu, T.J. H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

    2011-06-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  2. Analysis of core samples from the BPXA-DOE-USGS Mount Elbert gas hydrate stratigraphic test well: Insights into core disturbance and handling

    SciTech Connect

    Kneafsey, Timothy J.; Lu, Hailong; Winters, William; Boswell, Ray; Hunter, Robert; Collett, Timothy S.

    2009-09-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  3. Geophysical evidence for Quaternary deformation within the offshore San Andreas Fault System, Point Reyes Peninsula, California

    NASA Astrophysics Data System (ADS)

    Stozek, B.

    2010-12-01

    Our previous work studying the rate and style of uplift of marine terraces on the Point Reyes Peninsula indicates the peninsula has been undergoing differential uplift due to interacting fault geometries in the offshore zone. To better understand offshore fault interactions, recently collected mini-sparker seismic reflection data acquired by the USGS and multi-beam bathymetric data acquired by California State University at Monterey Bay within the 3-mile (5 km) limit offshore of the Point Reyes Peninsula, are being used to reinterpret the tectono-stratigraphic framework of the San Andreas fault (SAF) system. Eight offshore Shell exploratory well logs that provide seismic velocity and paleontologic data are being used in conjunction with industry multichannel (deep-penetration) seismic reflection profiles to provide age control and extend the analyses beyond 3 mile limit of the high-resolution data. Isopach and structure maps of key stratigraphic intervals were generated to show how the stratigraphic units are influenced by fault interactions. These datasets allow for new interpretations of the offshore Neogene stratigraphy and the evolution of the Point Reyes fault, an offshore component of the SAF system. Observations of Quaternary sedimentary sequences in the high-resolution mini-sparker dataset provide evidence of localized areas of subsidence and uplift within the offshore SAF system. For example, the most recent angular unconformity above the Point Reyes fault deepens to the north where the fault bends from an east-west to a more northerly orientation. Stratigraphic horizons in the offshore zone are correlated with the same geologic units exposed on the Point Reyes Peninsula. Both unconformity-bounded sedimentary sequences mapped on reflection profiles in the offshore and marine terraces that have been uplifted on the peninsula are tied to sea-level fluctuations. Our new interpretation of the Point Reyes fault zone will be incorporated into a kinematic fault model to test whether the inclusion of slip on the Point Reyes fault will replicate the observed uplift of marine terraces on the Point Reyes Peninsula. New interpretations of Point Reyes fault geometry may also clarify the faults interaction with the San Andreas and San Gregorio faults, and may require the reevaluation of the Point Reyes faults seismic hazard potential.

  4. Data from stratigraphic test holes drilled at the U.S. Marine Corps Air Station, Cherry Point, North Carolina, 1994-2001, and periodic water levels, 2000-2003

    USGS Publications Warehouse

    Wrege, Beth M.; Jen, Philip S.

    2004-01-01

    Nine stratigraphic test holes, from 158 to 305 feet deep, were drilled at the U.S. Marine Corps Air Station at Cherry Point, North Carolina, between 1994 and 2001 by the U.S. Geological Survey. These test holes and subsequent wells provide information about the lithology, stratigraphy, and geology at the Marine Corps Air Station. In addition, ground-water-level data were collected at the Air Station through 2003. The U.S. Geological Survey also conducted high-resolution marine and land seismic surveys during this investigation. The ground-water-level data and locations of the seismic survey lines are included in this report. The stratigraphic data combined with the seismic data provide a basis for the delineation of paleochannels beneath the Air Station as well as information for the management of water resources at the Air Station.

  5. Summary of Conclusions and Recommendations Drawn from the DeepCWind Scaled Floating Offshore Wind System Test Campaign: Preprint

    SciTech Connect

    Robertson, A. N.; Jonkman, J. M.; Masciola, M. D.; Molta, P.; Goupee, A. J.; Coulling, A. J.; Prowell, I.; Browning, J.

    2013-07-01

    The DeepCwind consortium is a group of universities, national labs, and companies funded under a research initiative by the U.S. Department of Energy (DOE) to support the research and development of floating offshore wind power. The two main objectives of the project are to better understand the complex dynamic behavior of floating offshore wind systems and to create experimental data for use in validating the tools used in modeling these systems. In support of these objectives, the DeepCwind consortium conducted a model test campaign in 2011 of three generic floating wind systems, a tension-leg platform (TLP), a spar-buoy (spar), and a semisubmersible (semi). Each of the three platforms was designed to support a 1/50th-scale model of a 5 MW wind turbine and was tested under a variety of wind/wave conditions. The focus of this paper is to summarize the work done by consortium members in analyzing the data obtained from the test campaign and its use for validating the offshore wind modeling tool, FAST.

  6. Model test of an inverted conical cylinder floating offshore wind turbine moored by a spring-tensioned-leg

    NASA Astrophysics Data System (ADS)

    Shin, Hyunkyoung; Cho, Sangrai; Jung, Kwangjin

    2014-03-01

    A new 5-MW floating offshore wind turbine moored by a spring-tensioned-leg was proposed for installation in about 50m water depth. Its substructure is a platform of the inverted conical cylinder type with massive ballast weight plate at the bottom. A 1:128 scale model was built for the preliminary engineering development. The model tests in waves and wind were carried out to estimate motion characteristics of this platform in the Ocean Engineering Wide Tank of the University of Ulsan. Its motions were measured and the RAOs were compared. The proposed floating offshore wind turbine showed a good stability and decent responses in waves, wind and operation of the wind turbine.

  7. Comparison of three marine screening tests and four Oslo and Paris Commission procedures to evaluate toxicity of offshore chemicals

    SciTech Connect

    Weideborg, M.; Vik, E.A.; Oefjord, G.D.; Kjoennoe, O.

    1997-02-01

    The results from the screening toxicity tests Artemia salina, Microtox{reg_sign}, and Mitochondria RET test were compared with those obtained from OSPAR (Oslo and Paris Commissions)-authorized procedures for testing of offshore chemicals (Skeletonema costatum, Acartia tonsa, Abra alba, and Corophium volutator). In this study 82 test substances (26 non-water soluble) were included. The Microtox test was found to be the most sensitive of the three screening tests. Microtox and Mitochondria RET test results showed good correlation with results from Acartia and Skeletonema testing, and it was concluded that the Microtox test was a suitable screening test as a base for assessment of further testing, especially regarding water-soluble chemicals. Sensitivity of Artemia salina to the tested chemicals was too low for it to be an appropriate bioassay organism for screening testing. A very good correlation was found between the results obtained with the Skeletonema and Acartia tests. The results indicated no need for more than one of the Skeletonema or Acartia tests if the Skeletonema median effective concentration or Acartia median lethal concentration was greater than 200 mg/L. The sediment-reworker tests (A. Alba or C. volutator) for chemicals that are likely to end up in the sediments (non-water soluble or surfactants) should be performed, independent of results from screening tests and other OSPAR species.

  8. Stratigraphic statistical curvature analysis techniques

    SciTech Connect

    Bengtson, C.A.; Ziagos, J.P.

    1987-05-01

    SCAT applies statistical techniques to dipmeter data to identify patterns of bulk curvature, determine transverse and longitudinal structural directions, and reconstruct cross sections and contour maps. STRAT-SCAT applies the same concepts to geometric interpretation of multistoried unimodal, bimodal, or trough-type cross-bedding and also to seismic stratigraphy-scale stratigraphic structures. Structural dip, which comprises the bulk of dipmeter data, is related to beds that (statistically) were deposited with horizontal attitudes; stratigraphic dip is related to beds that were deposited with preferentially oriented nonhorizontal attitudes or to beds that assumed such attitudes because of differential compaction. Stratigraphic dip generates local zones of departure from structural dip on special SCAT plots. The RMS (root-mean-square) of apparent structural dip is greatest in the (structural) T-direction and least in the perpendicular L-direction; the RMS of stratigraphic dip (measured with respect to structural dip) is greatest in the stratigraphic T*-direction and least in the stratigraphic L*-direction. Multistoried, cross-bedding appears on T*-plots as local zones of either greater scatter or statistically significant departure of stratigraphic median dip from structural dip. In contrast, the L*-plot (except for trough-type cross-bedding) is sensitive to cross-bedding. Seismic stratigraphy-scale depositional sequences are identified on Mercator dip versus azimuth plots and polar tangent plots as secondary cylindrical-fold patterns imposed on global structural patterns. Progradational sequences generate local cycloid-type patterns on T*-plots, and compactional sequences generate local cycloid-type patterns on T*-plots, and compactional sequences generate local half-cusp patterns. Both features, however, show only structural dip on L*-plots.

  9. Stratigraphic Signatures of Forearc Basin Formation Mechanisms

    NASA Astrophysics Data System (ADS)

    Mannu, U.; Ueda, K.; Gerya, T.; Willett, S.; Strasser, M.

    2014-12-01

    Forearc basins are loci of active sedimentation above the landward portion of accretionary prisms. Although these basins typically remain separated from the frontal prism by a forearc high, their evolution has a significant impact on the structure and deformation of the entire wedge. Formation of forearc basins has been proposed as a consequence of changes in wedge stability due to an increase of slab dip in subduction zones. Another hypothesis attributes this to higher hinterland sedimentation, which causes the rear of the wedge to stabilize and eventually develop a forearc basin. Basin stratigraphic architecture, revealed by high-resolution reflection seismic data and borehole data allows interpretation of structural development of the accretionary prism and associated basins with the goal of determining the underlying driving mechanism(s) of basin formation. In this study we supplement data interpretation with thermo-mechanical numerical models including high-resolution isochronal surface tracking to visualize the developing stratigraphy of basins that develop in subduction zone and wedge dynamic models. We use a dynamic 2D thermo mechanical model incorporating surface processes, strain weakening and sediment subduction. The model is a modification of I2VIS model, which is based on conservative, fully staggered finite differences and a non-diffusive marker- in-cell technique capable of modelling mantle convection. In the model different driving mechanisms for basin formation can be explored. Stratigraphic simulations obtained by isochronal surface tracking are compared to reflection pattern and stratigraphy of seismic and borehole data, respectively. Initial results from a model roughly representing the Nankai Trough Subduction Zone offshore Japan are compared to available seismic and Integrated Ocean Drilling (IODP) data. A calibrated model predicting forearc basin stratigraphy will be used to discern the underlying process of basins formation and wedge dynamics.

  10. Stratigraphic and palaeoenvironmental summary of the south-east Georgia embayment: a correlation of exploratory wells

    USGS Publications Warehouse

    Poppe, Lawrence J.; Popenoe, Peter; Poag, C. Wylie; Swift, B. Ann

    1995-01-01

    A Continental Offshore Stratigraphic Test (COST) well and six exploratory wells have been drilled in the south-east Georgia embayment. The oldest rocks penetrated are weakly metamorphosed Lower Ordovician quartz arenites and Silurian shales and argillites in the Transco 1005-1 well and Upper Devonian argillites in the COST GE-1 well. These marine strata, which are equivalent to the Tippecanoe sequence in Florida, underlie the post-rift unconformity and represent part of a disjunct fragment of Gondwana that was sutured to the North American craton during the late Palaeozoic Alleghanian orogeny. The Palaeozoic strata are unconformably overlain by interbedded non-marine Jurassic (Bajocian and younger) sandstones and shales and marginal marine Lower Cretaceous sandstones, calcareous shales and carbonates, which contain scattered beds of coal and evaporite. Together, these rocks are stratigraphically equivalent to the onshore Fort Pierce and Cotton Valley(?) Formations and rocks of the Lower Cretaceous Comanchean Provincial Series. The abundance of carbonates and evaporites in this interval, which reflects marine influences within the embayment, increases upwards, eastwards and southwards. The Upper Cretaceous part of the section is composed mainly of neritic calcareous shales and shaley limestones stratigraphically equivalent to the primarily marginal marine facies of the onshore Atkinson, Cape Fear and Middendorf Formations and Black Creek Group, and to limestones and shales of the Lawson Limestone and Peedee Formations. Cenozoic strata are primarily semiconsolidated marine carbonates. Palaeocene to middle Eocene strata are commonly cherty; middle Miocene to Pliocene strata are massive and locally phosphatic and glauconitic; Quaternary sediments are dominated by unconsolidated carbonate sands. The effects of eustatic changes and shifts in the palaeocirculation are recorded in the Upper Cretaceous and Tertiary strata.

  11. Monitoring Local and Teleseismic Earthquakes Off--Shore San Diego(California) During an OBSIP Test Deployment

    NASA Astrophysics Data System (ADS)

    Laske, G.; Babcock, J.; Hollinshead, C.; Georgieff, P.; Allmann, B.; Orcutt, J.

    2004-12-01

    The Scripps OBS (Ocean Bottom Seismometer) team is one of three groups that provide instrumentation for the US National OBS Instrument Pool (OBSIP). The compact active source LC2000 instruments are being used successfully in numerous experiments, with excellent data quality and return rates. A set of five new passive seismic instruments was test--deployed from November 6th, 2003 through January 8th, 2004 in the San Diego Trough, about 1km below the sea surface, about 40km off--shore San Diego, California. These instruments are equipped with a Nanometrics Trillium 40s 3--component seismometer and a Cox--Webb differential pressure gauge. We recorded more than 30 teleseismic earthquakes suitable for a long-period surface wave study. The vertical--component seismometer recordings are of excellent quality and are often superior to those from similar sensors on land (Guralp CMG-40T). The signal--to--noise ratio on the DPGs depend strongly on the water depth and was expected to be low for the test deployment. Nevertheless, the December 22, 2003 San Simeon/ California earthquake was recorded with high fidelity and non--seismogenic signals are extremely coherent down to very long periods. We also recorded numerous local earthquakes. Many of these occurred off-shore and the OBSs were the closest stations by many tens of kilometers. For example, a magnitude 3.0 earthquake on the Coronado Banks Fault was recorded at station SOL in La Jolla at about 30km distance, with a signal-to-noise ratio too poor to pick the first arrival. The next closest stations were 60km and 80km away, while one of the OBSs was only 20km away. The co-deployment of DPGs allowed us to observe the first P arrival very clearly. We also recorded numerous events that were not recorded on land. About six months later, on June 15, 2004 the greater San Diego area was struck by a magnitude 5.2 earthquake on the San Clemente Fault, about 40km southwest of the OBS test deployment. Though no structural damage was reported, intensity 4 shaking occurred throughout the city, which prompted Amtrak and Sea World to shut down operations for inspections. These events are continous reminders that significant seismic hazard is caused by activity along the only poorly understood, off-shore faults in the California Borderland. Realtime seismic monitoring using cabled or moored seismic observatories is clearly needed.

  12. Offshore Wind Research (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    This 2-page fact sheet describes NREL's offshore wind research and development efforts and capabilities. The National Renewable Energy Laboratory is internationally recognized for offshore wind energy research and development (R&D). Its experience and capabilities cover a wide spectrum of wind energy disciplines. NREL's offshore wind R&D efforts focus on critical areas that address the long-term needs of the offshore wind energy industry and the Department of Energy (DOE). R&D efforts include: (1) Developing offshore design tools and methods; (2) Collaborating with international partners; (3) Testing offshore systems and developing standards; (4) Conducting economic analyses; (5) Characterizing offshore wind resources; and (6) Identifying and mitigating offshore wind grid integration challenges and barriers. NREL has developed and maintains a robust, open-source, modular computer-aided engineering (CAE) tool, known as FAST. FAST's state-of-the-art capabilities provide full dynamic system simulation for a range of offshore wind systems. It models the coupled aerodynamic, hydrodynamic, control system, and structural response of offshore wind systems to support the development of innovative wind technologies that are reliable and cost effective. FAST also provides dynamic models of wind turbines on offshore fixed-bottom systems for shallow and transitional depths and floating-platform systems in deep water, thus enabling design innovation and risk reduction and facilitating higher performance designs that will meet DOE's cost of energy, reliability, and deployment objectives.

  13. Offshore medicine.

    PubMed

    Baker, D

    2001-03-01

    Offshore life can be refreshing for medics who are looking for a little change of pace; however, it is not for everyone. Working offshore can be the easiest or most boring job you'll ever have. It takes a specific type of medic to fit this mold. So, if you are considering a career in the offshore field, take all of the above into consideration. You are not just making a change in jobs, but a change in lifestyle. Once you become accustomed to this lifestyle, it will be hard to go back to the everyday hustle and bustle of the streets. For more information about working offshore, contact Acadian Contract Services at 800/259-333, or visit www.acadian.com. PMID:11258303

  14. World offshore

    SciTech Connect

    Redden, J.

    1984-07-20

    An update for offshore operations in the Bahamas, Gulf of Mexico, North Sea, Brazil, Australia, and Argentina is presented. The points of discussion are exploration targets, production figures, governmental controls, and drilling programs. There is some discussion of land leases.

  15. The 2011 Japanese 9.0 magnitude earthquake: Test of a kinetic energy wave model using coastal configuration and offshore gradient of Earth and beyond

    NASA Astrophysics Data System (ADS)

    Mahaney, William C.; Dohm, James M.

    2011-07-01

    Based on geological investigations of coastal geometry and stratigraphy, offshore gradient variation, wave velocity/energy, and quartz grain microtexture analysis of key sites inundated by tsunamis during the Holocene, we have developed a postulated model that could be used to assess modern and ancient onshore environmental conditions during tsunami emplacement. Given that tsunami waves can travel up to ~ 900 km/h, the kinetic energy of the wave is determined by frictional release on the offshore slope to seabed, nearshore sand and sediment supply, and coastal geomorphology, specifically coast linearity or embayments that constrict wave energy. With gentle offshore gradients and relatively linear coastlines, the kinetic energy of the tsunami is decreased by friction with the seabed and radiated outward along the coast, thus producing reduced flooding of the affected coast and fewer collisions of entrained grains. In contrast, steep offshore gradients reduce friction to mere milliseconds of wave impact, and embayments, specifically narrow coastal constrictions, increase wave energy, both of which increase on land run-up heights, and importantly to our proposed model, grain collision effects. Damage to quartz grains deposited by tsunamis along coastal extents ranges from slight on linear coasts with gentle offshore gradients to highly resurfaced mineral surfaces on coasts with steep offshore gradients and narrow embayments. Our model can be further tested through collection, analyses, and comparison of quartz grains in relatively low- and high-energy environments of the recently tsunami-impacted northeastern coast of Japan. For example, the location of the Fukushima nuclear plant along a linear coastline with a less steep offshore gradient may have attenuated the energy of the incoming wave, and thus yielding less resurfaced grains when compared to the coastline located to the north of Sendai City where coastal embayments of variable size coupled with steep offshore gradients would produce higher-energy waves of greater magnitude, as attested by greater penetration inland with considerable loss of life and property damage, and resulting highly deformed grain surfaces. The model could be applicable for assessing modern and ancient coastal environmental conditions on Earth and postulated ancient marine conditions on the Red Planet.

  16. Artificial lift with coiled tubing for flow testing the Monterey formation, offshore California

    SciTech Connect

    Peavy, M.A.; Fahel, R.A. )

    1991-05-01

    This paper provides a technical comparison of jet-pump and nitrogen lift during the drillstem tests (DST's) of a low-gravity, high-viscosity crude on a semisubmersible drilling vessel. Eight DST testing sequences are presented to demonstrate that jet-pump-lift operations are better suited than nitrogen-lift techniques for obtaining reservoir data during Monterey DST's.

  17. Eighteenth annual offshore technology conference. Volume 1

    SciTech Connect

    Not Available

    1986-01-01

    These sixty papers were given at a conference on offshore technology. Topics covered include friction effects of driving piles into sea beds of various compositions, wave forces on offshore platforms, stability, materials testing of various components such as plates, legs, wellheads, pipe joints, and protection of offshore platforms against ice and collision with icebergs.

  18. NaREC Offshore and Drivetrain Test Facility Collaboration: Cooperative Research and Development Final Report, CRADA Number CRD-04-140

    SciTech Connect

    Musial, W.

    2014-08-01

    The National Renewable Energy Laboratory (NREL) and the National Renewable Energy Centre (NaREC) in the United Kingdom (UK) have a mutual interest in collaborating in the development of full-scale offshore wind energy and drivetrain testing facilities. NREL and NaREC will work together to share resources and experiences in the development of future wind energy test facilities. This Cooperative Research and Development Agreement (CRADA) includes sharing of test protocols, infrastructure cost data, test plans, pro forma contracting instruments, and safe operating strategies. Furthermore, NREL and NaREC will exchange staff for training and development purposes.

  19. Flight test evaluation of a video tracker for enhanced offshore airborne radar approach capability

    NASA Technical Reports Server (NTRS)

    Clary, G. R.; Cooper, P. G.

    1982-01-01

    As a part of NASA's Rotorcraft All-Weather Operations Research Program, advanced airborne radar approach (ARA) concepts are being investigated. Since data from previous NASA/FAA flight tests showed significant ARA limitations, a research program was initiated at NASA Ames Research Center to determine the benefit that could be derived by automating certain radar functions and superimposing course display data on the radar display. To evaluate these concepts, a newly developed video tracking system which interfaces with weather radar was acquired. After the pilot designates a destination target, the system tracks the target video as it moves on the radar indicator. Using a small, efficient microprocessor, the autotracker presents valuable approach data on the radar screen and automatically adjusts the radar gain and tilt. Results of a limited flight test evaluation of the autotracker show that the course display concept, combined with automated gain and tilt functions, is effective for improving ARA's and reducing radar operator workload.

  20. Aerodynamic Thrust Modelling in Wave Tank Tests of Offshore Floating Wind Turbines Using a Ducted Fan

    NASA Astrophysics Data System (ADS)

    Azcona, Jos; Bouchotrouch, Faisal; Gonzlez, Marta; Garcianda, Joseba; Munduate, Xabier; Kelberlau, Felix; Nygaard, Tor A.

    2014-06-01

    Wave tank testing of scaled models is standard practice during the development of floating wind turbine platforms for the validation of the dynamics of conceptual designs. Reliable recreation of the dynamics of a full scale floating wind turbine by a scaled model in a basin requires the precise scaling of the masses and inertias and also the relevant forces and its frequencies acting on the system. The scaling of floating wind turbines based on the Froude number is customary for basin experiments. This method preserves the hydrodynamic similitude, but the resulting Reynolds number is much lower than in full scale. The aerodynamic loads on the rotor are therefore out of scale. Several approaches have been taken to deal with this issue, like using a tuned drag disk or redesigning the scaled rotor. This paper describes the implementation of an alternative method based on the use of a ducted fan located at the model tower top in the place of the rotor. The fan can introduce a variable force that represents the total wind thrust by the rotor. A system controls this force by varying the rpm, and a computer simulation of the full scale rotor provides the desired thrust to be introduced by the fan. This simulation considers the wind turbine control, gusts, turbulent wind, etc. The simulation is performed in synchronicity with the test and it is fed in real time by the displacements and velocities of the platform captured by the acquisition system. Thus, the simulation considers the displacements of the rotor within the wind field and the calculated thrust models the effect of the aerodynamic damping. The system is not able currently to match the effect of gyroscopic momentum. The method has been applied during a test campaign of a semisubmersible platform with full catenary mooring lines for a 6MW wind turbine in scale 1/40 at Ecole Centrale de Nantes. Several tests including pitch free decay under constant wind and combined wave and wind cases have been performed. Data from the experiments are compared with aero-servo-hydro-elastic computations with good agreement showing the validity of the method for the representation of the scaled aerodynamics. The new method for the aerodynamic thrust scaling in basin tests is very promising considering its performance, versatility and lower cost in comparison with other methods.

  1. The scientific objectives and program of the Japanese offshore methane hydrate production test

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Fujii, T.; Noguchi, S.; Nagao, J.

    2012-12-01

    A gas production attempt from deepwater marine methane hydrate deposits is planned in early 2013 in the AT1 site in the north slope Daini-Atsumi Knoll in the Eastern Nankai Trough. The scientific goal of this production test is to understand the behavior of methane hydrate dissociation under an in-situ condition. The program includes one to several weeks of gas flow by applying depressurization technique. Drilling operations for the production test started in February 2012 at the test location, and two monitoring boreholes and part of production well have been drilled and completed. Reservoir characterization study is an essential part of the science program. For this purpose, intensive geophysical logging and coring programs are included in the drilling program. The logging data were mainly obtained from a hole named AT1-MC. The well was drilled with LWD tools, wireline logging suits were run subsequently. Also pressure-preserved cores were recovered from methane hydrate-concentrated and overburden sections in a dedicated borehole (AT1-C). To keep the pressure and temperature of cores under gas hydrate stability condition all the time, pressure core analysis and transfer system (PCATS) was used. Also the PCATS-triaxial device that can make mechanical and physical property measurements possible under tri-axial effective stress conditions was utilized. The physical, hydraulic and mechanical properties obtained from core and log data will be used for modeling works, and given to the numerical simulator MH21-HYDRES for methane hydrate production modeling as input parameters for forward analysis and inversion (history matching) to understand the in-situ processes. The monitoring of the methane hydrate dissociation processes is another important subject. The two monitoring holes have temperature sensors to detect temperature drop and recovery due to gas hydrate dissociation and heat transfer. Also, one of the monitoring holes is kept re-accessible to allow cased-hole geophysical logging before and after the production test. A geophone array in an ocean bottom cable (OBC) will be deployed for a multi-component and time-lapse seismic survey on the seafloor. During the flow test, water and gas production rates, downhole temperature and pressure will be monitored. Comparison between actual well response and computed value from the numerical model will correct and improve our knowledge about reservoir characters and forecast of long-term productivity. JOGMEC, AIST and related scientists and engineers analyze the data to make unseen underground processes visible.;

  2. Sequence-Stratigraphic Analysis of the Regional Observation Monitoring Program (ROMP) 29A Test Corehole and Its Relation to Carbonate Porosity and Regional Transmissivity in the Floridan Aquifer System, Highlands County, Florida

    USGS Publications Warehouse

    Ward, W. C.; Cunningham, K.J.; Renken, R.A.; Wacker, M.A.; Carlson, J.I.

    2003-01-01

    An analysis was made to describe and interpret the lithology of a part of the Upper Floridan aquifer penetrated by the Regional Observation Monitoring Program (ROMP) 29A test corehole in Highlands County, Florida. This information was integrated into a one-dimensional hydrostratigraphic model that delineates candidate flow zones and confining units in the context of sequence stratigraphy. Results from this test corehole will serve as a starting point to build a robust three-dimensional sequence-stratigraphic framework of the Floridan aquifer system. The ROMP 29A test corehole penetrated the Avon Park Formation, Ocala Limestone, Suwannee Limestone, and Hawthorn Group of middle Eocene to Pliocene age. The part of the Avon Park Formation penetrated in the ROMP 29A test corehole contains two composite depositional sequences. A transgressive systems tract and a highstand systems tract were interpreted for the upper composite sequence; however, only a highstand systems tract was interpreted for the lower composite sequence of the deeper Avon Park stratigraphic section. The composite depositional sequences are composed of at least five high-frequency depositional sequences. These sequences contain high-frequency cycle sets that are an amalgamation of vertically stacked high-frequency cycles. Three types of high-frequency cycles have been identified in the Avon Park Formation: peritidal, shallow subtidal, and deeper subtidal high-frequency cycles. The vertical distribution of carbonate-rock diffuse flow zones within the Avon Park Formation is heterogeneous. Porous vuggy intervals are less than 10 feet, and most are much thinner. The volumetric arrangement of the diffuse flow zones shows that most occur in the highstand systems tract of the lower composite sequence of the Avon Park Formation as compared to the upper composite sequence, which contains both a backstepping transgressive systems tract and a prograding highstand systems tract. Although the porous and permeable layers are not thick, some intervals may exhibit lateral continuity because of their deposition on a broad low-relief ramp. A thick interval of thin vuggy zones and open faults forms thin conduit flow zones mixed with relatively thicker carbonate-rock diffuse flow zones between a depth of 1,070 and 1,244 feet below land surface (bottom of the test corehole). This interval is the most transmissive part of the Avon Park Formation penetrated in the ROMP 29A test corehole and is included in the highstand systems tract of the lower composite sequence. The Ocala Limestone is considered to be a semiconfining unit and contains three depositional sequences penetrated by the ROMP 29A test corehole. Deposited within deeper subtidal depositional cycles, no zones of enhanced porosity and permeability are expected in the Ocala Limestone. A thin erosional remnant of the shallow marine Suwannee Limestone overlies the Ocala Limestone, and permeability seems to be comparatively low because moldic porosity is poorly connected. Rocks that comprise the lower Hawthorn Group, Suwannee Limestone, and Ocala Limestone form a permeable upper zone of the Upper Floridan aquifer, and rocks of the lower Ocala Limestone and Avon Park Formation form a permeable lower zone of the Upper Floridan aquifer. On the basis of a preliminary analysis of transmissivity estimates for wells located north of Lake Okeechobee, spatial relations among groups of relatively high and low transmissivity values within the upper zone are evident. Upper zone transmissivity is generally less than 10,000 feet squared per day in areas located south of a line that extends through Charlotte, Sarasota, DeSoto, Highlands, Polk, Osceola, Okeechobee, and St. Lucie Counties. Transmissivity patterns within the lower zone of the Avon Park Formation cannot be regionally assessed because insufficient data over a wide areal extent have not been compiled.

  3. Evaluation of production tests in oil wells stimulated by massive acid fracturing offshore Qatar

    SciTech Connect

    McDonald, S.W.

    1983-03-01

    This paper presents the evaluation of pressure-buildup data from production tests in wells that have been stimulated by massive acid fracturing. Fracture type curves are used in combination with conventional semilog analysis techniques. Fracture characteristics are calculated from a match of the early-time pressure data with the type curves, and reservoir characteristics are calculated from a conventional semilog plot of late-time data. Unexpectedly high formation permeabilities are evaluated, and fracture half-lengths are much shorter than design values.

  4. Offshore wave energy experiment

    SciTech Connect

    Nielsen, K.; Scholten, N.C.; Soerensen, K.A.

    1995-12-31

    This article describes the second phase of the off-shore wave energy experiment, taking place in the Danish part of the North Sea near Hanstholm. The wave power converter is a scale model consisting of a float 2.5 meter in diameter connected by rope to a seabed mounted piston pump installed on 25 meter deep water 2,5 km offshore. The structure, installation procedure results and experience gained during the test period will be presented and compared to calculations based on a computer model.

  5. Borehole failure resulting from formation integrity (leak-off) testing in upper marine sediments offshore

    SciTech Connect

    Wojtanowicz, A.K.; Zhou, D.

    1998-12-31

    This paper presents results of potential loss of external integrity around casing shoe resulting from leak-off testing (LOT) in upper marine sediments (UMS). Three types of possible failures from LOTs are considered. It is proved that vertical fracture is the most unlikely failure for most UMS. Horizontal fracture can be formed in the plastic zone at a wellbore pressure less than overburden pressure, but it cannot extend beyond the plastic zone until the wellbore pressure exceeds the overburden pressure. An annular channel between cemented casing and rock is the other fracture way in UMS even though the cementing job is perfect. Fracture can be distinguished from LOT curve. Increasing the contact force between cemented casing and rock, such as using expanding cement, will prevent the formation of a harmful channel.

  6. Stratigraphic Units in Las Vegas Valley, Nevada

    NASA Astrophysics Data System (ADS)

    Donovan, D.

    2013-12-01

    Using 25 well logs, 15 of which also had accompanying geophysical and aquifer test data were used to describe and establish three alloformations including the Tule Spring and Paradise Valley Alloformations and four aquiformations, the most well defined being, the Las Vegas Springs Aquiformation, in the west central part of the bolson (Donovan, 1996), primarily in Township 20 South, Range 60 East, Mount Diablo Baseline and Meridian (MDBLM), with the stratotypes designated in T20S, R61E S31 MDBLM (36° 9'59.89"N 115°11'26.34"W). The allostratigraphic units were developed using the recommendations in the North American Code of Stratigraphic Nomenclature (NACSN, 1983 and 2005). The hydrostratigraphic units were developed following the recommendations of Seaber (1992). The units constitute the bulk of the upper 500 meter section. Twenty additional wells in the same geographic area, drilled and completed between 1995 and 2005 with detailed geologic and hydrologic information provided confirmation of these units. The proposed stratigraphic units are not part of either, and are located between, the two previously named and non-contiguous formations in the bolson (the Miocene Muddy Creek Formation and the late Pleistocene Las Vegas Formation) (Longwell et al 1965). Las Vegas Valley contains a metropolitan area of approximately two million people. The deeper part of the alluvial basin below 300 ft below ground surface is of interest for supply and storage. The shallower part is of interest for water quality and the interaction between the ground water system and engineered structures.

  7. Stratigraphic correlation for the IODP Expedition 347 - toward an integrated Baltic Sea Basin stratigraphy

    NASA Astrophysics Data System (ADS)

    Kotilainen, Aarno; Hyttinen, Outi; Andrén, Thomas; Cotterill, Carol; Hale, Walter; IODP Expedition 347 Science Party, the

    2014-05-01

    The IODP Expedition 347 - "Baltic Sea Paleoenvironment" completed in September - November 2013 (offshore phase) was the 5th and the final mission-specific platform (MSP) expedition of the Integrated Ocean Drilling Program. The expedition used a geotechnical drillship, the Greatship Manisha equipped with a Geoquip Marine coring rig, to core and wireline-log several sub-basins within the Baltic Sea, aiming to produce new information on the history of the Baltic Sea and climate change during the last glacial cycle. During the IODP Expedition 347 altogether over 1900 meters were successfully drilled at 8 Sites (M0059 - M0067) in the Lille Belt, Kattegat, Ångermanälven Estuary, Landsort Deep, Hanö Basin and Bornholm Basin with core recovery of approximately 1600 m (expansion adjusted core recovery of 91.46%). In this presentation, we show the preliminary results of regional stratigraphic correlation and splice results for the Expedition. That information provides a solid base for stratigraphic and high-resolution paleoenvironmental studies. Stratigraphic correlation consisted of the following: (1) ensuring the maximum core recovery on site, (2) seismic-core (sedimentary facies) correlation and (3) generating composite depth scales and splice records to each site. To obtain a complete sedimentary record, multiple adjacent holes were cored with an offset in depth of 0.5-1.5 m between cores from different holes. The continuity of recovery was assessed by generating composite sections that align prominent features in physical property data from adjacent holes. With the information gained by Fast Track Multi-Sensor Core Logger (MSCL) data, it was possible to adjust coring plan before the new hole, to ensure that intervals missing in previous cores could be recovered from an adjacent hole. Correlation between seismic profiles and cores used a simple estimation sound velocity vs. sediment type. Acquired depth was tested by comparison with major core surfaces, downhole logs, and the MSCL data (density and magnetic susceptibility). This data integration required preliminary interpretation of sedimentary units and comparisons with physical property boundaries. To align similar features in physical (geological) properties between different holes (or even different sites), MSCL physical property measurements were correlated (using Correlator software), to create a composite depth (mcd) scale. Splice records were generated by selecting sections from adjacent holes to avoid core gaps or disturbed sediment, resulting in a continuous record. This formed the basis for onshore sediment sampling and post-cruise research.

  8. A Risk Analysis Methodology to Address Human and Organizational Factors in Offshore Drilling Safety: With an Emphasis on Negative Pressure Test

    NASA Astrophysics Data System (ADS)

    Tabibzadeh, Maryam

    According to the final Presidential National Commission report on the BP Deepwater Horizon (DWH) blowout, there is need to "integrate more sophisticated risk assessment and risk management practices" in the oil industry. Reviewing the literature of the offshore drilling industry indicates that most of the developed risk analysis methodologies do not fully and more importantly, systematically address the contribution of Human and Organizational Factors (HOFs) in accident causation. This is while results of a comprehensive study, from 1988 to 2005, of more than 600 well-documented major failures in offshore structures show that approximately 80% of those failures were due to HOFs. In addition, lack of safety culture, as an issue related to HOFs, have been identified as a common contributing cause of many accidents in this industry. This dissertation introduces an integrated risk analysis methodology to systematically assess the critical role of human and organizational factors in offshore drilling safety. The proposed methodology in this research focuses on a specific procedure called Negative Pressure Test (NPT), as the primary method to ascertain well integrity during offshore drilling, and analyzes the contributing causes of misinterpreting such a critical test. In addition, the case study of the BP Deepwater Horizon accident and their conducted NPT is discussed. The risk analysis methodology in this dissertation consists of three different approaches and their integration constitutes the big picture of my whole methodology. The first approach is the comparative analysis of a "standard" NPT, which is proposed by the author, with the test conducted by the DWH crew. This analysis contributes to identifying the involved discrepancies between the two test procedures. The second approach is a conceptual risk assessment framework to analyze the causal factors of the identified mismatches in the previous step, as the main contributors of negative pressure test misinterpretation. Finally, a rational decision making model is introduced to quantify a section of the developed conceptual framework in the previous step and analyze the impact of different decision making biases on negative pressure test results. Along with the corroborating findings of previous studies, the analysis of the developed conceptual framework in this paper indicates that organizational factors are root causes of accumulated errors and questionable decisions made by personnel or management. Further analysis of this framework identifies procedural issues, economic pressure, and personnel management issues as the organizational factors with the highest influence on misinterpreting a negative pressure test. It is noteworthy that the captured organizational factors in the introduced conceptual framework are not only specific to the scope of the NPT. Most of these organizational factors have been identified as not only the common contributing causes of other offshore drilling accidents but also accidents in other oil and gas related operations as well as high-risk operations in other industries. In addition, the proposed rational decision making model in this research introduces a quantitative structure for analysis of the results of a conducted NPT. This model provides a structure and some parametric derived formulas to determine a cut-off point value, which assists personnel in accepting or rejecting an implemented negative pressure test. Moreover, it enables analysts to assess different decision making biases involved in the process of interpreting a conducted negative pressure test as well as the root organizational factors of those biases. In general, although the proposed integrated research methodology in this dissertation is developed for the risk assessment of human and organizational factors contributions in negative pressure test misinterpretation, it can be generalized and be potentially useful for other well control situations, both offshore and onshore; e.g. fracking. In addition, this methodology can be applied for the analysis of any high-risk operations, in not only the oil and gas industry but also in other industries such as nuclear power plants, aviation industry, and transportation sector.

  9. Stratigraphic and structural data for the Conasauga Group and the Rome Formation on the Copper Creek fault block near Oak Ridge, Tennessee: preliminary results from test borehole ORNL-JOY No. 2

    SciTech Connect

    Haase, C.S.; Walls, E.C.; Farmer, C.D.

    1985-06-01

    To resolve long-standing problems with the stratigraphy of the Conasauga Group and the Rome Formation on the Copper Creek fault block near Oak Ridge National Laboratory (ORNL), an 828.5-m-deep test borehole was drilled. Continuous rock core was recovered from the 17.7- to 828.5-m-deep interval; temperature, caliper, neutron, gamma-ray, and acoustic (velocity and televiewer) logs were obtained. The Conasauga Group at the study site is 572.4 m thick and comprises six formations that are - in descending stratigraphic order - Maynardville Limestone (98.8 m), Nolichucky Shale (167.9 m), Maryville Limestone (141.1 m), Rogersville Shale (39.6 m), Rutledge Limestone (30.8 m), and Pumpkin Valley Shale (94.2 m). The formations are lithologically complex, ranging from clastics that consist of shales, mudstones, and siltstones to carbonates that consist of micrites, wackestones, packstones, and conglomerates. The Rome Formation is 188.1 m thick and consists of variably bedded mudstones, siltstones, and sandstones. The Rome Formation thickness represents 88.1 m of relatively undeformed section and 100.0 m of highly deformed, jumbled, and partially repeated section. The bottom of the Rome Formation is marked by a tectonic disconformity that occurs within a 46-m-thick, intensely deformed interval caused by motion along the Copper Creek fault. Results from this study establish the stratigraphy and the lithology of the Conasauga Group and the Rome Formation near ORNL and, for the first time, allow for the unambiguous correlation of cores and geophysical logs from boreholes elsewhere in the ORNL vicinity. 45 refs., 26 figs., 2 tabs.

  10. Smarter offshoring.

    PubMed

    Farrell, Diana

    2006-06-01

    During the past 15 years, companies have flocked to a handful of cities in India and Eastern Europe for offshore service functions. As a result, the most popular sites are now overheating: Demand for young professionals is outstripping supply, wages and turnover are soaring, and overburdened infrastructure systems are struggling to serve the explosive growth. The happy news is that the tight labor markets in the well-known hot spots are the exceptions, not the rule. Many attractive alternatives are emerging around the world. According to a McKinsey Global Institute study, more than 90% of the vast and rapidly growing pool of university-educated people suitable for work in multinationals are located outside the current hot spot cities. For instance, Morocco is now home to offshore centers for French and Spanish companies requiring fluent speakers of their home languages. Neighboring Tunisia has used its modern infrastructure, business-friendly regulations, and stable, low-cost workforce to attract companies such as Siemens and Wanadoo. Vietnam offers university graduates who have strong mathematics skills; speak French, English, German, or Russian; and do not demand high wages. The problems facing the hot spots, coupled with the emergence of many more countries able and willing to provide offshore services, mean that picking a site has become more complicated. In choosing a location, companies will have to focus less on low wages and much more on other ways that candidate cities can fulfill their business needs. They will have to be much more rigorous in articulating precisely what they require from an offshore location. That means evaluating their unique needs on a range of dimensions and understanding how alternative locations can meet those needs for the foreseeable future. PMID:16770896

  11. Ice interaction with offshore structures

    SciTech Connect

    Cammaert, A.B.; Muggeridge, D.B.

    1988-01-01

    Oil platforms and other offshore structures being built in the arctic regions must be able to withstand icebergs, ice islands, and pack ice. This reference explain the effect ice has on offshore structures and demonstrates design and construction methods that allow such structures to survive in harsh, ice-ridden environments. It analyzes the characteristics of sea ice as well as dynamic ice forces on structures. Techniques for ice modeling and field testing facilitate the design and construction of sturdy, offshore constructions. Computer programs included.

  12. Application of TIMS data in stratigraphic analysis

    NASA Technical Reports Server (NTRS)

    Lang, H. R.

    1986-01-01

    An in-progress study demonstrates the utility of Thermal Infrared Multispectral Scanner (TIMS) data for unraveling the stratigraphic sequence of a western interior, North American foreland basin. The TIMS data can be used to determine the stratigraphic distribution of minerals that are diagnostic of specific depositional distribution. The thematic mapper (TM) and TIMS data were acquired in the Wind River/Bighorn area of central Wyoming in November 1982, and July 1983, respectively. Combined image processing, photogeologic, and spectral analysis methods were used to: map strata; construct stratigraphic columns; correlate data; and identify mineralogical facies.

  13. Offshore search continues despite disappointments

    SciTech Connect

    Cornitius, T.

    1985-05-01

    Exploration drilling activity in Australia broke records onshore in 1984, but offshore it was a different story. A total of 373 wells were drilled, onshore and offshore, with 266 labeled as wildcats and appraisals. Out of 80 wells drilled offshore last year, 43 were exploratory compared with 49 in 1983; 48 were oil wells, seven were gas, and 25 were dusters. Offshore discoveries included the Talisman 1 off the coast of Western Australia, which tested around 6000 b/d, and Challis 1 in the Timor Sea, which flowed at 5000 b/d. The failure to establish Jabiru in the Timor Sea as a major oil province like Bass Strait was a major disappointment. However, the Challis 1 was a relief since it indicated the presence of a commercial field adjacent to Jabiru.

  14. Some debatable problems of stratigraphic classification

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yury

    2014-05-01

    Russian geologists perform large-scale geological mapping in Russia and abroad. Therefore we urge unification of legends of geological maps compiled in different countries. It seems important to continuously organize discussions on problems of stratigraphic classification. 1. The stratigraphic schools (conventionally called "European" and "American") define "stratigraphy" in different ways. The former prefers "single" stratigraphy that uses data proved by many methods. The latter divides stratigraphy into several independent stratigraphers (litho-, bio-, magneto- and others). Russian geologists classify stratigraphic units into general (chronostratigraphic) and special (in accordance with a method applied). 2. There exist different interpretations of chronostratigraphy. Some stratigraphers suppose that a chronostratigraphic unit corresponds to rock strata formed during a certain time interval (it is somewhat formalistic because a length of interval is frequently unspecified). Russian specialists emphasize the historical-geological background of chronostratigraphic units. Every stratigraphic unit (global and regional) reflects a stage of geological evolution of biosphere and stratisphere. 3. In the view of Russian stratigraphers, the main stratigraphic units may have different extent: a) global (stage), b) regional (regional stage,local zone), and c) local (suite). There is no such hierarchy in the ISG. 4. Russian specialists think that local "lithostratigraphic" units (formations) which may have diachronous boundaries are not chronostratigraphic ones in strict sense (actually they are lithological bodies). In this case "lithostratigraphy" can be considered as "prostratigraphy" and employed in initial studies of sequences. Therefore, a suite is a main local unit of the Russian Code and differs from a formation, although it is somewhat similar. It does not mean that lithostratigraphy is unnecessary. Usage of marker horizons, members and other bodies is of great help. Lithostratigraphy may be regarded as the start of geological mapping on scales of 1 : 10 000, 1 : 25 000 or 1 : 50 000, and lithostratigraphic subdivisions can be used as the mapping units because they practically have isochronic boundaries when we deal with geological mapping on these scales. 5. Russian geologists interpret a chronozone (defined with due account of the standard assemblage-zone) as a part of a stage. In opinion of other specialists, zones serve as correction markers. This gives rise to controversy where zonal scales are needed for the Phanerozoic or whether stage scales are sufficient. In the Russian Code a chronozone is referred to general stratigraphic units (less than a stage). 6. The popular GSSP "concept" may be is inadequate in the broad sense because stages remain "empty" and do not reflect geological events. The search of "golden spikes" can be useful as a part of comprehensive investigations of stratigraphic subdivisions. "Silver" and other type spike-markers can be used as well as recommended by event stratigraphy (Ager, 1973). 7. A new version of "International Stratigraphic Guide" should include not only recommendations but also alternative views. However the work must not be done in a hurry! In avoid bias representatives of interested countries should be involved. Finally, I would like to make two proposals. Proposal 1. A special symposium should be held during the second International Congress on Stratigraphy-2015 to review national stratigraphic codes (USA, Germany, Great Britain, China, Russia, Australia and other countries). This can provide better understanding of their similarities and dissimilarities and enable to realize how much they differ from each other. The review may show the present state of the stratigraphic classification and reveal both pressing and alleged problems of stratigraphy of the early XXI century. Proposal 2. It would be appropriate to prepare a special publication presenting briefly codes of different countries. Every national code is described on two pages: a tabled stratigraphic classification on one page and comments on another. Such publication would be most helpful.

  15. Offshore Socotra, Republic of Yemen: Potential for a new hydrocarbon province?

    SciTech Connect

    Richardson, S.M.; Bott, W.F.; Birse, T.C.R.

    1995-08-01

    A new plate reconstruction has enabled the Island of Socotra, currently located in the Gulf of Aden adjacent to the Somalian coast, to be confidently restored to its original spatial position, adjacent to the southern Omani coastline. New studies integrated with these plate reconstructions, have confirmed the presence of an untested Mesozoic graben, which trends across the Socotra platform. Fieldwork carried out in the region now enables a SE extension of the prolific Lower Cretaceous Qishn `play` (delinated in the Masilah Basin, onshore Yemen) to be postulated offshore into the Gulf of Aden. Following the award of offshore acreage adjacent to the Island of Socotra, exploration studies have confirmed the presence of the Qishn `play` both on the Island of Socotra, and offshore in the one available basin-margin control well. This work has also identified two additional plays: the Shuabia-equivalent carbonates, which are prolific producing reservoirs in central Oman; and the Permo-Triassic clastics, which may provide a new reservoir target for the region. Fieldwork has also identified Jurassic siliclastics outcropping on the Island, which may provide further reservoir potential. Ongoing multidisciplinary studies, integrating the results of a detailed geophysical interpretation with high resolution structural-stratigraphic studies, have confirmed the presence of large structures within an undrilled Mesozoic rift-basin, which will be tested during 1995.

  16. Stratigraphic framework of productive carbonate buildups

    SciTech Connect

    Greenlee, S.M.; Lehmann, P.J. )

    1990-05-01

    Hydrocarbon-productive carbonate buildups are found within a relatively narrow window of geologic time and stratigraphic settings. Because buildups are common exploration objectives in frontier and mature basins, an understanding of their stratigraphic occurrence permits them to be more accurately explored. Based on a worldwide survey, most production occurs in isolated periods of geologic time: Middle Silurian-Late Silurian, late Middle and Late Devonian, Late Pennsylvanian and Early Permian, Late Cretaceous, Paleocene, and Miocene. The authors results suggest that many factors of successful buildup plays are predictable on the basis of geohistory analysis and of basin-filling stratal patterns. Deposition of extensive source beds and thick buildups coincide with second-order eustatic rises. Other primary controls on the temporal distribution of buildups include reef-building organism type, mineralogy, and paleolatitude. Geohistory analysis indicates that periods immediately prior to or during the earliest portion of rapid increases of accommodation correspond to times of productive buildup growth. During this time, shelf margins step landward and buildups become progressively more areally restricted. Buildups eventually are unable to keep pace with high rates of accommodation increase and often are overlain by distal toes of clinoforms within regressive wedges deposited during subsequent periods with lower rates of accommodation increase. The result is a stratigraphic juxtaposition of mounded reservoir carbonate and deep-marine sealing shale. This basin-fill position accounts for over 70% of known buildup-reservoired hydrocarbons. Buildups deposited in overlying regressive wedges are often lower relief and prone to seal problems.

  17. Underbalanced drilling benefits now available offshore

    SciTech Connect

    Vozniak, J.P.; Cuthbertson, B.; Nessa, D.O.

    1997-05-01

    Offshore underbalanced drilling (UBD) is a reality. Applications in older, partially depleted fields and new fields are being considered. However, low productivity reservoirs and fields with sub normal pressures causing drilling problems are currently the main targets for offshore UBD. With proper planning and the correct technique, both jointed pipe and coiled tubing UBD drilling operations have been carried out offshore with success. The main concerns for offshore UBD have been altered drilling practices and surface production system operation. These issues have been examined and equipment has been designed and tested to address them. Environmental, safety and health issues are paramount and have been studied carefully. Detailed well planning, engineering, and flow modeling have proven critical for successful offshore UBD operations. Examples are given from oil and gas fields.

  18. Sequence stratigraphic interpretations in a continental strike-slip Basin - Southern Dead Sea, Israel

    SciTech Connect

    Csato, I.; Kendall, C.

    1996-12-31

    Sequence stratigraphic interpretations of subsurface data from the Southern Dead Sea have been integrated with computer modeling of the stratigraphy, demonstrating that the sedimentary fill was controlled by extremely high rates of subsidence (1000 m/MY), salt tectonics, multiple sediment sources, and lake-level fluctuations. The southern part of the basin is underlain by half-grabens and full-grabens. A northwest-southeast directed shear zone (5-6 km wide) closes the basin to the north, while the large Amaziahu growth fault, developed by gravity sliding and salt-withdrawal, separates the basin into two segments. Fan deltas entered the basin at its southern and northern ends, while salt and lacustrine offshore sediments accumulated in its interior. The southern and northern lacustrine systems interfinger in a mixing zone which changed position as a function of lake-level variations. The advance of the northern system was accompanied by lake level falls, while lake-level rises favored an influx from the southern system. The northern sedimentary system gradually became more dominant. The stratigraphic simulation revealed that the lake-level falls paralleled those of the Mediterranean sea, but with a slight (0.3-0.4 MY) delay. Combined stratigraphic and thermal maturation modeling suggests that sediments in the deepest part of the basin are currently within the oil generation window. Significant pinch-out zones flanking the Mount Sedom diapir, buried fan delta complexes, and the peculiar interfingering, zones may be important exploration targets.

  19. Sequence stratigraphic interpretations in a continental strike-slip Basin - Southern Dead Sea, Israel

    SciTech Connect

    Csato, I.; Kendall, C.

    1996-01-01

    Sequence stratigraphic interpretations of subsurface data from the Southern Dead Sea have been integrated with computer modeling of the stratigraphy, demonstrating that the sedimentary fill was controlled by extremely high rates of subsidence (1000 m/MY), salt tectonics, multiple sediment sources, and lake-level fluctuations. The southern part of the basin is underlain by half-grabens and full-grabens. A northwest-southeast directed shear zone (5-6 km wide) closes the basin to the north, while the large Amaziahu growth fault, developed by gravity sliding and salt-withdrawal, separates the basin into two segments. Fan deltas entered the basin at its southern and northern ends, while salt and lacustrine offshore sediments accumulated in its interior. The southern and northern lacustrine systems interfinger in a mixing zone which changed position as a function of lake-level variations. The advance of the northern system was accompanied by lake level falls, while lake-level rises favored an influx from the southern system. The northern sedimentary system gradually became more dominant. The stratigraphic simulation revealed that the lake-level falls paralleled those of the Mediterranean sea, but with a slight (0.3-0.4 MY) delay. Combined stratigraphic and thermal maturation modeling suggests that sediments in the deepest part of the basin are currently within the oil generation window. Significant pinch-out zones flanking the Mount Sedom diapir, buried fan delta complexes, and the peculiar interfingering, zones may be important exploration targets.

  20. 3D Stratigraphic Modeling of Central Aachen

    NASA Astrophysics Data System (ADS)

    Dong, M.; Neukum, C.; Azzam, R.; Hu, H.

    2010-05-01

    Since 1980s, advanced computer hardware and software technologies, as well as multidisciplinary research have provided possibilities to develop advanced three dimensional (3D) simulation software for geosciences application. Some countries, such as USA1) and Canada2) 3), have built up regional 3D geological models based on archival geological data. Such models have played huge roles in engineering geology2), hydrogeology2) 3), geothermal industry1) and so on. In cooperating with the Municipality of Aachen, the Department of Engineering Geology of RWTH Aachen University have built up a computer-based 3D stratigraphic model of 50 meter' depth for the center of Aachen, which is a 5 km by 7 km geologically complex area. The uncorrelated data from multi-resources, discontinuous nature and unconformable connection of the units are main challenges for geological modeling in this area. The reliability of 3D geological models largely depends on the quality and quantity of data. Existing 1D and 2D geological data were collected, including 1) approximately 6970 borehole data of different depth compiled in Microsoft Access database and MapInfo database; 2) a Digital Elevation Model (DEM); 3) geological cross sections; and 4) stratigraphic maps in 1m, 2m and 5m depth. Since acquired data are of variable origins, they were managed step by step. The main processes are described below: 1) Typing errors of borehole data were identified and the corrected data were exported to Variowin2.2 to distinguish duplicate points; 2) The surface elevation of borehole data was compared to the DEM, and differences larger than 3m were eliminated. Moreover, where elevation data missed, it was read from the DEM; 3) Considerable data were collected from municipal constructions, such as residential buildings, factories, and roads. Therefore, many boreholes are spatially clustered, and only one or two representative points were picked out in such areas; After above procedures, 5839 boreholes with -x, -y, -z coordinates, down-hole depth, and stratigraphic information are available. 4) We grouped stratigraphic units into four main layers based on analysis of geological settings of the modeling area. The stratigraphic units extend from Quaternary, Cretaceous, Carboniferous to Devonian. In order to facilitate the determination of each unit boundaries, a series of standard code was used to integrate data with different descriptive attributes. 5) The Quaternary and Cretaceous units are characterized by subhorizontal layers. Kriging interpolation was processed to the borehole data in order to estimate data distribution and surface relief for the layers. 6) The Carboniferous and Devonian units are folded. The lack of software support, concerning simulating folds and the shallow depth of boreholes and cross sections constrained the determination of geological boundaries. A strategy of digitalizing the fold surfaces from cross sections and establishing them as inclined strata was followed. The modeling was simply subdivided into two steps. The first step consisted of importing data into the modeling software. The second step involved the construction of subhorizontal layers and folds, which were constrained by geological maps, cross sections and outcrops. The construction of the 3D stratigraphic model is of high relevance to further simulation and application, such as 1) lithological modeling; 2) answering simple questions such as "At which unit is the water table?" and calculating volume of groundwater storage during assessment of aquifer vulnerability to contamination; and 3) assigned by geotechnical properties in grids and providing them for user required application. Acknowledgements: Borehole data is kindly provided by the Municipality of Aachen. References: 1. Janet T. Watt, Jonathan M.G. Glen, David A. John and David A. Ponce (2007) Three-dimensional geologic model of the northern Nevada rift and the Beowawe geothermal system, north-central Nevada. Geosphere, v. 3; no. 6; p. 667-682 2. Martin Ross, Michel Parent and Ren Lefebvre (2005) 3D geologic

  1. Offshore Essaouira basin: Geology and hydrocarbon potential

    SciTech Connect

    Jabour, H.; Ait Salem, A. )

    1991-03-01

    The study area lies in the offshore extension of the onshore Essaouria basin. The Mesozoic development of the Essaouira margin was largely controlled by Late Triassic to Mid-Jurassic rifting and subsequent opening of the Central Atlantic, with the evolution of a typical passive, opening of the Central Atlantic, with the evolution of a typical passive, continental margin. Diapiric salt structure recognized on seismic defines a Late Triassic-Early Jurassic salt basin in the offshore area initiated during early rifting. Subsidence and sea-level rise during Jurassic resulted in carbonate platform development. This was followed during Cretaceous and Tertiary time by the deposition of a prograding siliciclastic system. Only three wells have been drilled in this basin. Although drilled on poorly defined prospects, these wells encountered gas and oil shows. Fairly extensive seismic coverage of good quality data is now available. A study based on an integrated approach involving seismic facies definition and mapping, correlation with well data, identification of the principal control on sedimentation, and basin modeling in conjunction with source rock prediction and maturity modeling has been carried out. Results have shown that hydrocarbon potential in the offshore Essaouira basin has not yet been substantiated by drilling. Attractive structural and stratigraphic prospects exist in the shelf, shelf edge, and the slope, and await confirmation by drilling.

  2. Stratigraphic Paleobiology of the Taranto Area

    NASA Astrophysics Data System (ADS)

    Scarponi, Daniele; Angeletti, Lorenzo; Taviani, Marco; Huntley, John Warren; Amorosi, Alessandro; Negri, Alessandra; Battista Vai, Gian

    2015-04-01

    The area surrounding Taranto, Italy is chronostratigraphically very important, as it is one of the few areas in the world where Upper Pleistocene marine successions are well exposed, easily accessible, and relatively thick. Several outcrops in this area were investigated as suitable marine sections for defining the Late Pleistocene GSSP. At these locations, the late Pleistocene bathymetric history of the Taranto area was depicted using macrobenthic assemblages from a network of outcrops and cores. Outcrops at Pontile, Fronte, and Garitta, along with two cores drilled at Cimino and Cantoro were densely sampled to conduct quantitatively-derived paleobathymetric reconstructions. These deposits yielded relatively diverse mollusk associations (> 250 species and > 9.000 specimens distributed among 55 samples), dominated by extant mollusk species of known bathymetric distribution. Multiple analytical approaches were applied to the macrobenthic dataset in a comparative fashion: (i) direct calibration by weighted averaging of taxa with known preferred depth recovered in a sample, (ii) posteriori-calibrated ordination (DCA) using bathymetric data of key extant taxa. These analyses were conducted at both species and genus level. Regardless of the choice of the analytical method, mollusk assemblages yielded bathymetric trends congruent with previous qualitative and semi-quantitative paleoecological and stratigraphic analyses: the bathymetric range of sampled deposits is bracketed between 140 and 0 meters. Secondly, macrobenthos-derived proxies provided an improved characterization of the marine deposits in terms of sample bathymetry and by discriminating shallowing-upward (regressive) trends from deepening-upward (transgressive) tendencies. Thirdly, mollusk-derived bathymetric inferences suggest spatial bathymetric gradients that are coherent with the morphology of the study area. In conclusion, the results provided an improved characterization of coastal depositional facies in a sequence stratigraphic perspective, which is one of the primary research goals of Stratigraphic Paleobiology.

  3. Complex Stratigraphic Evolution of the Red Sea

    NASA Astrophysics Data System (ADS)

    Almalki, Khalid A.; Mahmud, Syed A.

    2015-04-01

    The Red Sea rift, separates the African and the Arabian continents, and is considered a type location of a juvenile rift-related small ocean. Geological studies and drilling programs date back to more than half a century yet very little is known about the stratigraphic evolution to the wider geological community. Following the arrival of the Afar plume at the late Oligocene (ca 30 Ma) the southern Red Sea underwent rapid extension culminating in extended continental crust or seafloor spreading, which stalled during the early Miocene at the central Red Sea due to either slowing of the convergence between Arabia and Eurasia or the onset of the Arabian plate passive margin collision with Eurasia. The mainland pan of the region was uplifted, resulting in the development of the Red Sea erosional escarpment. Shelf sedimentation (Middle-late Miocene to Pleistocene successions) then ensued and covered oceanic and continental crust. The present day spreading centre resumed in the southern Red Sea at 5 Ma and has been propagating northward until the present-day. However, detailed analysis of the basin shows a more complex pattern of basin development with late Oligocene succession restricted to the western Red Sea coast and the southern sectors. Well data suggest that up to 4 km of sediments exist in the southern Red Sea shallowing upward to the northern sector; 3 km or more of this section consists of Miocene evaporates, which contains intercalated anhydrite and shale horizons. These Miocene evaporates are overlain by Quaternary reefal limestone, and recent volcanic rocks restricted to the central axial trough zone of the Red Sea. In this study extensive well data that is well spread in the area was used to evaluate the stratigraphic architecture, build-ups, and local controls on deposition. Potential stratigraphic models have been developed. The distribution of stratigraphy in the Red Sea area yields complex correlation, with unique depositional characteristics in discrete zones within the Red Sea basin.

  4. Evaluation of LBZ susceptibility of offshore structural steels by CTOD and instrumented pre-crack Charpy impact test

    SciTech Connect

    Aihara, Shuji; Okamoto, Kentaro

    1994-12-31

    Toughness of simulated HAZ was evaluated by means of CTOD and instrumented pre-crack Charpy tests. While the CTOD transition temperature represents brittle fracture initiation toughness, pre-crack Charpy transition temperature is strongly influenced by brittle fracture arrest toughness. The both transition temperatures are controlled by different microstructural parameters.

  5. Quantifying the stratigraphic completeness of delta shoreline trajectories

    NASA Astrophysics Data System (ADS)

    Mahon, Robert C.; Shaw, John B.; Barnhart, Katherine R.; Hobley, Daniel E. J.; McElroy, Brandon

    2015-05-01

    Understanding the incomplete nature of the stratigraphic record is fundamental for interpreting stratigraphic sequences. Methods for quantifying stratigraphic completeness for one-dimensional stratigraphic columns, defined as the proportion of time intervals of some length that contain stratigraphy, are commonplace; however, quantitative assessments of completeness in higher dimensions are lacking. Here we present a metric for defining stratigraphic completeness of two-dimensional shoreline trajectories using topset-foreset rollover positions in dip-parallel sections and describe the preservation potential of a shoreline trajectory derived from the geometry of the delta surface profile and the kinematics of the geomorphic shoreline trajectory. Two end-member forward models are required to fully constrain the preservation potential of the shoreline dependent on whether or not a topset is eroded during base level fall. A laboratory fan-delta was constructed under nonsteady boundary conditions, and one-dimensional stratigraphic column and two-dimensional shoreline completeness curves were calculated. Results are consistent with the hypothesis derived from conservation of sediment mass that completeness over all timescales should increase given increasing dimensions of analysis. Stratigraphic trajectories and completeness curves determined from forward models using experimental geomorphic trajectories compare well to values from transects when subsampled to the equivalent stratigraphic resolution as observed in the actual preserved sequence. The concept of stratigraphic completeness applied to two-dimensional trajectory analysis and the end-member forward models presented here provide novel tools for a conceptual understanding of the nature of stratigraphic preservation at basin scales.

  6. Drilling and data acquisition programs for the methane hydrate offshore production test in the Eastern Nankai Trough

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Fujii, T.

    2013-12-01

    Marine methane hydrates are a matter of scientific interests from various viewpoints such as a key player of global carbon cycle, effects on climate change, cause of seafloor instability, and a possible future energy resource. Under the Japanese national research program, the MH21 research consortium (Japan Oil, Gas and Metals National Corporation and National Institute of Advanced Industrial Science and Technology) has conducted survey operations and subsequent analyses of data and samples from methane hydrate-bearing sediments in the Eastern Nankai Trough. The goal of the project was a gas production test from a methane hydrate deposits in sandy intervals of Pleistocene turbidite sediments. The test location was set in Daini Atsumi Knoll that is a ridge between forearc basin and accretionary prism, and the sediments cover the flank of the knoll. The water depth at the test location is approximately 1000m, and 50m thick methane hydrate concentrated zone exists around 300m below seafloor. The main interest of the MH21 research team is to know physical (thermal, hydraulic, and mechanical) parameters of sediments that are necessary to understand gas hydrate dissociation processes during the production test. Core samples and geophysical logging data obtained during past surveys are utilized for this purpose. Sedimentation and tectono-geophysical conditions govern such material properties, so the samples were analyzed from those viewpoints, too. The first drilling at the location was done in 2004 with logging and coring operation including pressure-conserved core sampling. In 2011, shallow geotechnical survey holes were drilled in the area for geo-hazard assessment, and core samples were taken in the holes, along with some in-situ mechanical and hydraulic testings. In early 2012, a well construction operation for the gas production test was conducted with logging operations that contains neutron porosity data using pulse-neutron devices, magnetic resonance log, etc. A core sampling operation followed in the middle of 2012 using an improved pressure-coring tool and analysis devices. In the March of 2013, the gas production attempt was started using 'depressurization method,' in which liquid in the wellbore was removed by downhole pump to drawdown pore pressure in the formation. The test was accomplished with six day methane gas production. Gas flow rate from the single borehole by depressurization procedure (original 13.5MPa to 4.5MPa at the bottom of the borehole) could provid 20,000Sm3/day gas before the test was forced to terminate due to a sand production problem. An intensive monitoring program accompanied with the test, including two monitoring borehole for time-lapse cased-hole logging and temperature measurements. Moreover, multi-component and time-lapse seismic survey was done using an ocean bottom cable. The taken flow rate, pressure and temperature data, and gas, liquid and solid samples are under detailed analyses to understand the response of methane hydrates in the sediments against depressurization operation, and may provide knowledge of hydrogeology and thermodynamics information of the methane hydrate bearing strata. Some detailed study results are presented in this session and posters.

  7. Offshore yearbook, 1987

    SciTech Connect

    Not Available

    1987-01-01

    This book is an annual compilation of information and articles on offshore petroleum operations. It includes an industry analysis, engineering highlights, a news review of the Western Hemisphere, and an industry outlook for 1987. It provides survey information on deepwater wells, worldwide offshore daily oil production, producing fields by country, and international offshore well count. It also contains mobile rig statistics, including rig scrappings, rig name changes, cold-stacked and for-sale units, and unit types.

  8. Europa's Northern Trailing Hemisphere: Lineament Stratigraphic Framework

    NASA Technical Reports Server (NTRS)

    Figueredo, P. H.; Hare, T.; Ricq, E.; Strom, K.; Greeley, R.; Tanaka, K.; Senske, D.

    2004-01-01

    Knowledge of the global distribution of Europan geologic units in time and space is a necessary step for the synthesis of the results of the Galileo mission and in preparation for future exploration (namely, by JIMO) of the satellite. We have initiated the production of the first Global Geological Map of Europa. As a base map, we use the recently published global photomosaic of Europa (U.S.G.S. Map I-2757) and additional Galileo SSI images at their original resolution. The map is being produced entirely on GIS format for analysis and combination with other datasets [1]. One of the main objectives of this project is to establish a global stratigraphic framework for Europa. In the absence of a well-developed cratering record, this goal will be achieved using the satellite s global network of lineaments (ridges, ridge complexes and bands; cf. [2]). Here we present the preliminary stratigraphic framework synthesized from the sequence of lineaments derived for the northern trailing hemisphere of Europa (Figure 1, below), and we discuss its significance and some emerging implications.

  9. Sedimentary sequence of offshore southeastern US: preliminary study based on exploration wells

    SciTech Connect

    Libby-French, J.

    1984-04-01

    In 1982, geologic data from the exploratory wells in the offshore southeastern US were released to the public. Prior to this time, well data were limited the the COST (Continental Offshore Stratigraphic Test) GE-1 well, the first deep-penetration well, which was completed in 1977. Six additional exploration wells were completed thereafter. Although these wells were dry holes, information provided by them has contributed to the geologic interpretation of the Atlantic margin. The oldest rocks penetrated by these wells are Paleozoic indurated shale and argillite, sandstone and weakly metamorphosed quartzite, and igneous rocks. The post-Paleozoic section ranges from 2220 to 3660 m (7280 to 12,000 ft) thick at the well sites, but seismic data indicate that equivalent section thickens to 10-12 km (6-7 mi) beneath the Blake plateau. The Lower Cretaceous through Cenozoic section represents a progression from nonmarine and marginal marine to marine sedimentation. Three main units are recognized: lower siliciclastic, middle calcareous mudstone, and upper limestone. The siliciclastic unit consists of interbedded gray to red-brown sandstone, siltstone, and shale with some conglomerate, coal, evaporites, and carbonate rocks. Based on petrographic examination, the sandstone compositions, vary between arkose, litharenite, and quartz arenite. Calcareous clay and shale (grading to shaly limestone) overlie the siliciclastic rocks. The upper limestone contains chert, oolites, and shell fragments and ranges in composition from micrite to sparite. By comparing these units to the onshore Georgia sedimentary section, regional lithofacies trends that can be useful for future exploration are recognized.

  10. Deformational and stratigraphic influences on mineralization in SE Ireland

    NASA Astrophysics Data System (ADS)

    McArdle, P.; Kennan, P. S.

    1992-06-01

    The evidence that has accumulated to date to support the thesis that deformational and stratigraphic controls are reflected in the occurrence and siting of metal deposits in SE Ireland is evaluated. In the case of an important tungsten deposit, stratigraphic influences can be seen in the geochemical and mineralogical development of wallrocks prior to crystallization of granite-hosted mineralization. Tourmalinites, confined to a definable stratigraphic interval, are associated with pegmatite-hosted lithium deposits. Though the stratigraphic control is important, the tungsten and lithium deposits are, in addition, confined to the trace of a major deformation zone.

  11. Methane hydrate pore saturation evaluation from geophysical logging and pressure core analysis, at the first offshore production test site in the eastern Nankai Trough, Japan

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Suzuki, K.; Takayama, T.; Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Nagao, J.

    2013-12-01

    On March 2013, the first offshore production test form methane hydrate (MH) concentrated zone (MHCZ) was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21) at the AT1 site located in the north-western slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. Before the production test, extensive geophysical logging and pressure coring using Hybrid Pressure Coring System were conducted in 2012 at monitoring well (AT1-MC) and coring well (AT1-C), in order to obtain basic information for the MH reservoir characterization. MH pore saturation (Sh) is one of the important basic parameters not only for reservoir characterization, but also the resource assessment. However, precise evaluation of Sh from geophysical logging is still challenging technical issue. The MHCZ confirmed by the geophysical logging at AT1-MC has a turbidite assemblage (from several tens of centimeters to a few meters) with 60 m of gross thickness; it is composed of lobe/sheet type sequences in the upper part, and relatively thick channel sand sequences in the lower part. In this study, the Sh evaluated from geophysical logging data were compared with those evaluated from pressure core analysis. Resistivity logs and nuclear magnetic resonance (NMR) log were used for the Sh evaluation by geophysical logging. Standard Archie equation was applied for Sh evaluation from resistivity log, while density magnetic resonance (DMR) method was used for Sh evaluation from NMR log. The Sh from pressure core samples were evaluated using the amount of dissociated gas volume, together with core sample bulk volume, measured porosity, net sand intervals, and assumed methane solubility in pore water. In the upper part of the MHCZ, Sh estimated from resistivity log showed distinct difference in value between sand and mud layers, compared to Sh from NMR log. Resistivity log has higher vertical resolution than NMR log, so it is favorable for these kinds of thin bed evaluation. In this part, 50 to 80% of Sh was observed in sandy layer, which showed fairly good agreement with core derived Sh. On the other hand, lower part of the MHCZ, Sh estimated from both resistivity and NMR log showed higher background value and relatively smoother curve than upper part. In this part, 50 to 80% of Sh was observed in sandy layer, which was also showed good agreement with core derived Sh. This study was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21).

  12. Tectonic-stratigraphic division and blind fold structures in Nansha Waters, South China Sea

    NASA Astrophysics Data System (ADS)

    Yan, Pin; Liu, Hailing

    2004-12-01

    Extensive multiple-channel reflection seismic data have been collected in the Nansha (Spratley Islands) Waters, the southern margin of the South China Sea. Stratigraphic correlation is shown with focus on a comprehensive geophysiXcal survey line run from offshore NW Sabah to offshore SE Vietnam. According to the varying tectono-stratigraphy from southeast to northwest, five tectonic belts can be determined, i.e. the Palawan-Borneo Nappe, Nansha Trough, Nanwei-Liyue Compressive Belt, Zheng'he Extensional Belt and the Circum-Southwest Subbasin Belt. In the Palawan-Borneo Nappe, Neogene-Quaternary deposits were highly upthrust northwestwards, resulting in a series of moderately to tightly folded anticlines separated by open synclines. The Nansha Trough was a narrow, deep-water belt filled with thick, undisturbed Neogene-Quaternary deposits. The Nanwei-Liyue Compressive Belt was dominated by strongly folded paleo-anticlines overlain by an undeformed sedimentary cap with a pronounced hiatus of Paleogene sediments. The Zheng'he Extensional Belt consisted of a rugged topography and Paleogene half-grabens bounded by listic faults. The major extensional faults were reactivated to cut through the overlying Neogene-Quaternary deposits. Over the Circum-Southwest Subbasin Belt, Neogene-Quaternary deposits draped on the largely subsided fault blocks related to the Late Oligocene-Mid-Miocene seafloor spreading. Based on the regional stratigraphic correlation, the prominent paleo-anticlines found within the Nanwei-Liyue Compressive Belt are deduced to consist of mainly Mesozoic marine sediments that were compressed in the Late Mesozoic Era. Therefore, the Nansha Microcontinent Block is shown to be a collision complex assembled during Late Mesozoic Era.

  13. Stratigraphic data for wells at and near the Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Anderson, S.R.; Ackerman, D.J.; Liszewski, M.J.; Frieburger, R.M.

    1996-05-01

    A stratigraphic data base containing 230 stratigraphic units in 333 wells was constructed for deposits that make up the unsaturated zone and the Snake River Plain aquifer at and near INEL in eastern Idaho. Stratigraphic units, which were identified and correlated using data from numerous outcrops, 26 continuous cores, and 328 natural-gamma logs available in Dec. 1993, include 121 basalt-flow groups, 102 sedimentary interbeds, 6 andesite-flow groups, and 1 rhyolite dome. By volume, basalt flows make up about 90% of the deposits underlying most of this 890 mi{sup 2} area. Basalt, sediment, andesite, and rhyolite were identified from outcrops and cores that were selectively evaluated. Stratigraphic units were correlated using these data and natural-gamma logs. Best correlations were for basalt and sediment at Test Area North, the Naval Reactors Area, the Test Reactor Area, ICPP, and the Radioactive Waste Management Complex (RWMC), where most cores and 2/3 of the logs were obtained. Correlations range from good at the RWMC to uncertain the eastern half of the study area. A computer diskette containing the data is included.

  14. Servicing the offshore industry

    SciTech Connect

    1997-03-01

    What factors are leading operators to using boat-based services vs. those that are rig-based for offshore completions, stimulations and workovers? What trends are companies experiencing in completion practices for the unconsolidated formations in the Gulf of Mexico? What are companies` most important specifications for well service boats operating near their offshore platforms? To answer these and other questions, Petroleum Engineering International asked those who should know -- the producing companies active in offshore operations in the Gulf of Mexico and worldwide.

  15. Stratigraphic architecture of the Cryogenian successions of South China

    NASA Astrophysics Data System (ADS)

    Zhu, M.; Yin, Z.; Zhang, J.; Condon, D. J.; Macdonald, F. A.; Liu, P.

    2014-12-01

    Stratigraphy and sedimentology of the Cryogenian glacial successions provide primary data for elucidating climatic change of this critical interval. The Cryogenian strata of South China were deposited in a rift basin, and exhibit dramatic facies change from the basin center to margin, which complicates stratigtraphic correlations. Here we present new sedimentological, geochemical and stratigraphic data based on the detailed analyses of more than ten well exposed sections along a basinward transect from north-south. In the basin center, Cryogenian strata are about 4000 m thick and characterized by two glaciogenic diamictite units separated by a diamictite-free siliciclastic interval. Initiation of the Chang'an glaciation (Sturtian equivalent) is conformable and gradational with dropstones appearing in siltstone at the basal part of the Chang'an Formation followed by a shoaling-up sequence that is interpreted to represent a glacio-eustatic sea-level fall. In the basin center, >600 m of graded beds of siliciclastic rocks and debrites of the Fulu Formation overlie the Chang'an Formation. The Fulu Formation is succeeded by a thin (<10 m) fine-grained siliciclasitic unit with black shale and manganese carbonate at the base, which is assigned to the Datangpo Formation, and massive glacigenic diamitictite of the Marinoan-age Nantuo Formation. On the basin margin, the Datangpo Formation is up to 300 m thick and is underlain by a glaciogentic diamictite (Tiesi'ao/Dongshanfeng/Gucheng Formations). Taking factors of glacial dynamics and active tectonism into account, we develop a facies model to interpret the sedimentology and stratigraphic architecture of these successions. Combined with new geochronological data, our data will provide tests for Cryogenian climatic models.

  16. Tectonic and stratigraphic evolution in South Alboran Sea (Morocco)

    NASA Astrophysics Data System (ADS)

    D'Acremont, E.; Gorini, C.; El Abbassi, M.; Farran, M.; Leroy, S.; Mercier De Lepinay, B. F.; Migeon, S.; Poort, J.; Ammar, A.; Smit, J.; Ercilla, G.; Alonso, B.; Scientific Team of the Marlboro project

    2011-12-01

    The Alboran Basin, in western Mediterranean, concentrates on a relatively small surface and densely-populated, a large structural complexity linked to seismic activity with recurrent mass-transport deposits that may trigger tsunamis. It was formed by Oligo-Miocene extension while tectonic inversion occurred since the Late Miocene (Tortonian) due to the African-European collision. This North-South compression produces a conjugated fault system located in the central area from Al Hoceima to Andalusia. Numerous instabilities are linked to the recent and present-day seismic activity and show the link between seismicity and erosion-sedimentation processes. On the Andalusia margin the active structures have been identified and recently mapped in detail by using MBES data (including backscatter), and high-resolution seismic data. Such detailed studies have not yet been carried out on the Moroccan margin. The Marlboro-1 oceanographic cruise (R/V Ctes de la Manche, July 2011) has imaged and constrained active structures and associated sedimentary systems through seismic reflection data (MCS). The Xauen/Tofino banks (growth folds), the Alboran Ridge, and the Al Hoceima basin offshore Morocco have been selected because they constitute key-study areas that record a complete deformation history since the Tortonian. Active features including faults, growth folds, channels, mass transport deposits, contourites and volcanoes has provided first order tectonic and sedimentary markers of the basin's evolution. A high chrono-stratigraphical resolution will constitute the basis for reconstructing the evolution of this tectonically active area marked by strong seismic activity. The Marlboro-1 cruise will allow determining key-study area of the Marlboro-2 cruise scheduled for 2012 (R/V Tthys-II, CNFC Call). These cruises should allow for the acquisition of data necessary to characterize basin morphology, active tectonic and sedimentary structures and also make the link with existing 2D seismic lines that image deeper structures. The Marlboro proposals are linked to the international MerAlbo and SARAS cruises (Ifremer-IPEV-IRD and Eurofleets proposals), the French Termex CNRS Program, Actions Marges research group, and the Spanish and European programs Contouriber and Topomed. The aim of these cruises is to acquire a full geophysical and geological dataset to allow increase our knowledge and understanding of the tectonic and sedimentary processes acting at different spatial and temporal scales that are responsible for creating potentially catastrophic events such as earthquakes, slope failures and consequently tsunamis.

  17. Session: Offshore wind

    SciTech Connect

    Gaarde, Jette; Ram, Bonnie

    2004-09-01

    This session at the Wind Energy and Birds/Bats workshop consisted of two presentations. Due to time constraints, a discussion period was not possible. The session addressed the current state of offshore wind energy development. The first presentation ''Monitoring Program and Results: Horns Rev and Nysted'' by Jette Gaarde summarized selected environmental studies conducted to date at operating offshore wind turbine projects in Denmark and lessons from other offshore wind developments in Europe. Wildlife impacts studies from the Danish sites focused on birds, fish, and mammals. The second presentation ''What has the U.S. Wind Industry Learned from the European Example'' by Bonnie Ram provided an update on current permit applications for offshore wind developments in the U.S. as well as lessons that may be drawn from the European experience.

  18. Probabilistic sequence alignment of stratigraphic records

    NASA Astrophysics Data System (ADS)

    Lin, Luan; Khider, Deborah; Lisiecki, Lorraine E.; Lawrence, Charles E.

    2014-10-01

    The assessment of age uncertainty in stratigraphically aligned records is a pressing need in paleoceanographic research. The alignment of ocean sediment cores is used to develop mutually consistent age models for climate proxies and is often based on the δ18O of calcite from benthic foraminifera, which records a global ice volume and deep water temperature signal. To date, δ18O alignment has been performed by manual, qualitative comparison or by deterministic algorithms. Here we present a hidden Markov model (HMM) probabilistic algorithm to find 95% confidence bands for δ18O alignment. This model considers the probability of every possible alignment based on its fit to the δ18O data and transition probabilities for sedimentation rate changes obtained from radiocarbon-based estimates for 37 cores. Uncertainty is assessed using a stochastic back trace recursion to sample alignments in exact proportion to their probability. We applied the algorithm to align 35 late Pleistocene records to a global benthic δ18O stack and found that the mean width of 95% confidence intervals varies between 3 and 23 kyr depending on the resolution and noisiness of the record's δ18O signal. Confidence bands within individual cores also vary greatly, ranging from ~0 to >40 kyr. These alignment uncertainty estimates will allow researchers to examine the robustness of their conclusions, including the statistical evaluation of lead-lag relationships between events observed in different cores.

  19. Stratigraphic evolution of paleozoic erathem, northern Florida

    SciTech Connect

    Coleman, J.L. Jr.

    1985-02-01

    Unmetamorphosed Paleozoic sedimentary and volcanic rocks have been drilled in numerous wells throughout northern Florida and southern Georgia, in what is today a gently folded and block-faulted relict continental fragment of northwest Africa and northeast South America. Stratigraphic and lithologic equivalents of these North American Paleozoic units are prolific hydrocarbon producers in North Africa. The northern Florida Paleozoic sediments were deposited on Pan-African and Cadoman basement. Widespread continental glaciation from late Precambrian to Early Cambrian introduced a thick sequence of fine-grained marine sandstones (glacial flour), which overlie medium to coarse-grained glaciofluvial sandstones. Basinward of the sand shelf, the accretion of a volcanic island arc complex began during the Ordovician. A fluctuating transgression, accompanying a major glacial minimum, brought open-marine, graptolitic, black shales onto the sand shelf, producing an interbedded shoreface-shelf sand and black shale section during the Middle and Late Ordovician. At the Ordovician-Silurian boundary, renewed continental glaciation lowered sea level, producing a widespread unconformity. A Late Silurian major marine transgression returned black, graptolitic, highly organic shales onto the sand shelf. Devonian deltaic sands from Avalonia(.) to the north and the craton to the south closed the Paleozoic sedimentary record of northern Florida.

  20. Economics of Developing Hot Stratigraphic Reservoirs

    SciTech Connect

    Greg Mines; Hillary Hanson; Rick Allis; Joseph Moore

    2014-09-01

    Stratigraphic geothermal reservoirs at 3 – 4 km depth in high heat-flow basins are capable of sustaining 100 MW-scale power plants at about 10 c/kWh. This paper examines the impacts on the levelized cost of electricity (LCOE) of reservoir depth and temperature, reservoir productivity, and drillhole/casing options. For a reservoir at 3 km depth with a moderate productivity index by hydrothermal reservoir standards (about 50 L/s/MPa, 5.6 gpm/psi), an LCOE of 10c/kWh requires the reservoir to be at about 200°C. This is the upper temperature limit for pumps. The calculations assume standard hydrothermal drilling costs, with the production interval completed with a 7 inch liner in an 8.5 inch hole. If a reservoir at 4 km depth has excellent permeability characteristics with a productivity index of 100 L/s/MPa (11.3 gpm/psi), then the LCOE is about 11 c/kWh assuming the temperature decline rate with development is not excessive (< 1%/y, with first thermal breakthrough delayed by about 10 years). Completing wells with modest horizontal legs (e.g. several hundred meters) may be important for improving well productivity because of the naturally high, sub-horizontal permeability in this type of reservoir. Reducing the injector/producer well ratio may also be cost-effective if the injectors are drilled as larger holes.

  1. Selected stratigraphic contacts for drill holes in LANL use areas of Yucca Flat, NTS

    SciTech Connect

    Drellack, S.L. Jr.

    1988-07-01

    This report is a compilation of selected stratigraphic contacts in drill holes of Yucca Flat, Nevada Test Site (NTS), used by the Los Alamos National Laboratory (LANL). This is the product of an ongoing effort to establish and maintain the most up-to-date database of formation tops in LANL use areas of Yucca Flat. Figure 1 is an index map showing areas of the NTS covered in this report. A drill hole planning map showing hole locations is in the rear pocket. Data presented for each drill hole include drill hole name; year drill hole completed; ground level elevations, above mean sea level (MSL), at drill hole site; total depth (TD) of drill hole at completion of drilling; and depth below surface to selected stratigraphic contacts. The geologic data presented here was generated by numerous individuals. Published references, from which most of these data originated, are listed on page 54 of this report. Information regarding other drill hole statistics can be found in the NTS Drilling and Mining Summary (``The Redbook``) compiled by the Technical Support Division of Fenix and Scisson, Inc. We continue the ``revised`` stratigraphic nomenclature for the bedded tuffs between the Rainier Mesa Member of the Timber Mountain Tuff and the Grouse Canyon Member of the Belted Range Tuff (formerly the ``Paintbrush Tuff``). Confidence in these stratigraphic assignments for these bedded tuffs is consolidating. 13 refs., 4 figs., 2 tabs.

  2. Regional method to assess offshore slope stability.

    USGS Publications Warehouse

    Lee, H.J.; Edwards, B.D.

    1986-01-01

    The slope stability of some offshore environments can be evaluated by using only conventional acoustic profiling and short-core sampling, followed by laboratory consolidation and strength testing. The test results are synthesized by using normalized-parameter techniques. The normalized data are then used to calculate the critical earthquake acceleration factors or the wave heights needed to initiate failure. These process-related parameters provide a quantitative measure of the relative stability for locations from which short cores were obtained. The method is most applicable to offshore environments of gentle relief and simple subsurface structure and is not considered a substitute for subsequent site-specific analysis. -from ASCE Publications Information

  3. Submarine fans in a sequence stratigraphic framework

    SciTech Connect

    Posamentier, H.W.; Erskine, R.D.; Mitchum, R.M.; Vail, P.R.

    1987-05-01

    Submarine fans are fan- or cone-shaped turbiditic deposits formed in upper bathyal or deeper water depths. Within a sequence stratigraphic framework, these basin-floor turbidites can occur during lowstand-fan or lowstand-wedge systems tract time. During lowstand fan time, streams are rejuvenated and depocenters shift from the coastal plain to the upper slope, causing retrogradational slope failure and canyon formation. The sediment delivered here bypasses the canyon and continues down the slope as a succession of gravity flows and is deposited as fan-shaped turbiditic deposits at the base of the slope. Seismic and outcrop evidence suggest that these sand-prone deposits are abruptly introduced into the basin and are generally characterized by subtle external mounding and internal bidirectionally down lapping seismic reflections where seismically resolvable. Deep-water sediment deposited during this interval has no coeval shelf equivalent. During lowstand wedge time, streams cease down cutting and valleys which have been freshly incised begin to fill. Because coarse sediment will preferentially be deposited within these incised valleys, the sand-to-mud ratio delivered to the upper slope will be decreased and, consequently, there is an inherent difference between submarine fans deposited at this time and those deposited during lowstand fan time. Deposition during lowstand wedge time is characterized seismically by slope front fill or wedge-shaped geometries down lapping the earlier submarine fan (i.e., deposited during lowstand fan time). These shale-prone deposits are largely comprised of thinner-bedded turbidites as well as the occasional leveed channel.

  4. Stratigraphic sequence analysis of the Antler foreland

    SciTech Connect

    Silberling, N.J.; Nichols, K.M.; Macke, D.L. )

    1993-04-01

    Mid-Upper Devonian to Upper Mississippian strata in western Utah were deposited in the distal Antler foreland. They record lateral and vertical changes in depositional environments that define five successive stratigraphic sequences, each representing a third-order transgressive-regressive cycle. In ascending order, these sequences are informally named the Langenheim (LA) of late Frasnian to mid-Famennian age, the Gutschick (GU) of late Famennian to early Kinderhookian age, the Morris (MO) of late Kinderhookian age; the Sadlick (SA) of Osagean to early Meramecian age, and the Maughan (MA) of mid-Meramecian to Chesterian age. MO is widespread and recognized within carbonate rocks of the Fitchville Formation and Joana Limestone. SA formed in concert with and to the east and south of the Wendover foreland high; the Delle phosphatic event marks maximum marine flooding during SA deposition. The transgressive systems tract of MA includes rhythmic-bedded limestone in the upper part of the Deseret Limestone in west-central Utah and, farther west, the hypoxic limestone and black shale of the Skunk Spring Limestone Bed and part of the overlying Chainman Shale. Traced westward into Nevada, MA first oversteps SA and then MO. Lithostratigraphic correlation of these sequences still farther west into the Eureka thrust belt (ETB) could mean that the youngest strata truncated by the Roberts Mountains thrust belong to the MA and that this thrust is simply part of the post-Mississippian ETB. However, some strata in central Nevada that lithically resemble those of the MA are paleontologically dated as Early Mississippian, the age of sequences overstepped by MA not far to the east. Thus, at least some imbricates of the ETB may contain a sequence stratigraphy which reflects local tectonic control.

  5. Salt Repository Project site study plan for stratigraphic boreholes: Revision 1, December 18, 1987

    SciTech Connect

    Not Available

    1987-12-18

    This site study describes the Stratigraphic Boreholes field work to be conducted during the early stages of Site Characterization at the Deaf Smith County, Texas site. The field program has been designed to provide data useful in addressing information/data needs resulting from Federal/State/local regulations, and repository program requirements. Four Stratigraphic Holes will be drilled near the perimeter of the site to document the subsurface geologic conditions in that area and to provide data necessary for design and construction of the Exploratory Shaft Facilities. Continuous samples will be recovered from the ground surface to the total depth of each sell. Geophysical well logs will provide additional coverage of the stratigraphic section. In-situ down hole testing will include short term hydrologic tests and hydraulic fracture tests to provide information on deep groundwater characteristics and regional stress patterns, respectively. Field methods/tests are chosen that provide the best or only means of obtaining the required data. The Salt Repository Project (SRP) Networks specify the schedule which the program will operate. The Technical Services Contractor is responsible for conducting the field program of drilling and testing. Samples and data will be handled and reported in accordance with established SRP procedures. A quality assurance program will be utilized to assure that activities affecting quality are performed correctly and that the appropriate documentation is maintained. 30 refs., 13 figs., 4 tabs.

  6. Getting offshoring right.

    PubMed

    Aron, Ravi; Singh, Jitendra V

    2005-12-01

    The prospect of offshoring and outsourcing business processes has captured the imagination of CEOs everywhere. In the past five years, a rising number of companies in North America and Europe have experimented with this strategy, hoping to reduce costs and gain strategic advantage. But many businesses have had mixed results. According to several studies, half the organizations that have shifted processes offshore have failed to generate the expected financial benefits. What's more, many of them have faced employee resistance and consumer dissatisfaction. Clearly, companies have to rethink how they formulate their offshoring strategies. A three-part methodology can help. First, companies need to prioritize their processes, ranking each based on two criteria: the value it creates for customers and the degree to which the company can capture some of that value. Companies will want to keep their core (highest-priority) processes in-house and consider outsourcing their commodity (low-priority) processes; critical (moderate-priority) processes are up for debate and must be considered carefully. Second, businesses should analyze all the risks that accompany offshoring and look systematically at their critical and commodity processes in terms of operational risk (the risk that processes won't operate smoothly after being offshored) and structural risk (the risk that relationships with service providers may not work as expected). Finally, companies should determine possible locations for their offshore efforts, as well as the organizational forms--such as captive centers and joint ventures--that those efforts might take. They can do so by examining each process's operational and structural risks side by side. This article outlines the tools that will help companies choose the right processes to offshore. It also describes a new organizational structure called the extended organization, in which companies specify the quality of services they want and work alongside providers to get that quality. PMID:16334588

  7. Instrumented Pressure Testing Chamber (IPTC) Characterization of Methane Gas Hydrate-Bearing Pressure Cores Collected from the Methane Production Test Site in the Eastern Nankai Trough, Offshore Japan

    NASA Astrophysics Data System (ADS)

    Waite, W. F.; Santamarina, J. C.; Dai, S.; Winters, W. J.; Yoneda, J.; Konno, Y.; Nagao, J.; Suzuki, K.; Fujii, T.; Mason, D. H.; Bergeron, E.

    2014-12-01

    Pressure cores obtained at the Daini-Atsumi Knoll in the eastern Nankai Trough, the site of the methane hydrate production test completed by the Methane Hydrate Resources in Japan (MH21) project in March 2013, were recovered from ~300 meters beneath the sea floor at close to in situ pressure. Cores were subsequently stored at ~20 MPa and ~5C, which maintained hydrate in the cores within stability conditions. Pressure core physical properties were measured at 10 MPa and ~6C, also within the methane hydrate stability field, using the IPTC and other Pressure Core Characterization Tools (PCCTs). Discrete IPTC measurements were carried out in strata ranging from silty sands to clayey silts within the turbidite sequences recovered in the cores. As expected, hydrate saturations were greatest in more permeable coarser-grained layers. Key results include: 1) Where hydrate saturation exceeded 40% in sandy sediments, the gas hydrate binds sediment grains within the matrix. The pressure core analyses yielded nearly in situ mechanical properties despite the absence of effective stress in the IPTC. 2) In adjacent fine-grained sediment (hydrate saturation < 15%), hydrate did not significantly bind the sediment. IPTC results in these locations were consistent with the zero effective-stress limit of comparable measurements made in PCCT devices that are designed to restore the specimen's in situ effective stress. In sand-rich intervals with high gas hydrate saturations, the measured compressional and shear wave velocities suggest that hydrate acts as a homogeneously-distributed, load-bearing member of the bulk sediment. The sands with high gas hydrate saturations were prone to fracturing (brittle failure) during insertion of the cone penetrometer and electrical conductivity probes. Authors would like to express their sincere appreciation to MH21 and the Ministry of Economy, Trade and Industry for permitting this work to be disclosed at the 2014 Fall AGU meeting.

  8. The stratigraphic distribution of large marine vertebrates and shell beds in the Pliocene of Tuscany

    NASA Astrophysics Data System (ADS)

    Dominici, Stefano; Benvenuti, Marco; Danise, Silvia

    2015-04-01

    The record of 337 shark fossils, 142 cetaceans and 10 sea cows from the Pliocene of Tuscany, mostly from historical museum collections, is revised. The majority of these fossils are concentrated at a few geographic sites from separated hinterland basins, on the South-Western side of the Northern Apennines. To better understand the meaning of these concentrations, the sequence stratigraphic distribution of more recent findings of large marine vertebrates is reconstructed against a high-resolution framework based on sedimentary facies analysis. These remains are usually covered by, or included in mudstones deposited far from the coast (N=12), skeletons being usually articulated, slightly displaced, and often bioeroded. A minor part of better preserved articulated skeletons is associated with sandstones from deltaic paleonenvironments (N=2). Marine mammal and shark remains may be associated with laterally-continuous shell accumulations, a type of concentration occurring at maximum flooding surfaces, separating relatively coarse-grained facies from open marine mudstones. Shell beds were bulk-sampled at 66 locations from six basins, covering a wide range of sedimentary facies, and spanning a chronologic interval of about 2.5 million years. A dataset of 62,655 mollusc specimens belonging to 496 species formed the basis of a statistical study to reconstruct the structure of the benthic communities, and to estimate paleodepths from intertidal to upper bathyal settings. Mollusc associations closely mirror the distribution of sedimentary facies, allowing for a fine tuning of the sequence stratigraphic architecture. Merging paleogeographic, stratigraphic and paleoecologic data, we conclude that the more abundant and diverse accumulations of large vertebrates took place in settings under the influence of coastal upwelling. A modern analogue occurs today in the Ligurian Sea, on the Tuscan offshore, where abundant nutrients carried by deep-marine currents of Western origin, within an otherwise oligotrophic Mediterranean Sea, sustain a rich and diverse cetacean and shark, epipelagic and mesopelagic community. The modern steep bathymetric gradient was displaced towards the East during the Pliocene, before the latest phases of uplift of the Northern Apennines. An open marine, nutrient-rich ecosystem influenced hinterland basins during major transgressive pulses, leading to a higher productivity and the formation of laterally-continuos accumulations of biogenic hard parts. A comparison with the few available studies on the sequence-stratigraphic distribution of large marine vertebrates and shell beds suggests that a model integrating high-productivity and sea level rise, favouring bone bed and shell bed formation, can be applied at other settings, and other geologic intervals.

  9. Impact of lithosphere deformation on stratigraphic architecture of passive margin basins

    NASA Astrophysics Data System (ADS)

    Rouby, Delphine; Huismans, Ritske; Robin, Ccile; Braun, Jean; Granjeon, Didier

    2015-04-01

    The aim of this study is to revise our view of the long-term stratigraphic trends of passive margins to include the impact of the coupling between the lithosphere deformation and the surface processes using a numerical experimentation approach. To do this, we first simulated the syn-rift phase of lithosphere stretching by thermo-mechanical modeling. We then used the deformed lithosphere geometry as input of a 3D flexural modeling including coupling with surface processes to simulate the post-rift evolution of the margin. We then use the corresponding accumulation and subsidence histories as input of the stratigraphic model to simulate the detailed stratigraphic architecture of the basin. We tested this procedure using synthetic examples of lithosphere stretching based on end-members rheologies of the lithosphere (i.e. strength of the lower crust) for narrow or ultra-wide rifting modes. We determined the stratigraphic architecture of the basins of each conjugate margin using three grain-sizes (sand, silt, and clay) differing in their transport length. In all cases, uplift/subisdence rates decrease with time while the flexure wavelength increases as isotherms are re-equilibrated. Some areas show displacement inversion over time from uplift to subsidence (or vice-versa). As expected, the amplitude of vertical motion of the wide margin cases is very limited with respect to the narrow margin case. Vertical motions are very asymetric on conjugate margins. Accordingly, the stratigraphic architectures and the sedimentation/erosion patterns of the conjugate simulated margins are significantly different mostly because the duration and length of progradation and retrogradation differ. We evaluated the sensitivity of the simulations to parameters controlling (i) the lithosphere deformation, (ii) the continental drainage erosivity (climate) or (iii) erodability (lithology) as well as (iv) base level (eustasy).

  10. The stratigraphic filter and bias in measurement of geologic rates

    USGS Publications Warehouse

    Schumer, Rina; Jerolmack, Douglas; McElroy, Brandon

    2011-01-01

    Erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power-law dependence on measurement interval. This dependence can result from a power-law distribution of stratigraphic hiatuses. By representing the stratigraphic filter as a stochastic process called a reverse ascending ladder, we describe a likely origin of power-law hiatuses, and thus, rate scaling. While power-law hiatuses in certain environments can be a direct result of power-law periods of stasis (no deposition or erosion), they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift. Autocorrelation in fluctuations can make hiatuses more or less heavy-tailed, but still exhibit power-law characteristics. In addition we show that by passing stratigraphic data backward through the filter, certain statistics of surface kinematics from their formative environments can be inferred.

  11. The stratigraphic filter and bias in measurement of geologic rates

    USGS Publications Warehouse

    Schumer, R.; Jerolmack, D.; McElroy, B.

    2011-01-01

    Erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power-law dependence on measurement interval. This dependence can result from a power-law distribution of stratigraphic hiatuses. By representing the stratigraphic filter as a stochastic process called a reverse ascending ladder, we describe a likely origin of power-law hiatuses, and thus, rate scaling. While power-law hiatuses in certain environments can be a direct result of power-law periods of stasis (no deposition or erosion), they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift. Autocorrelation in fluctuations can make hiatuses more or less heavy-tailed, but still exhibit power-law characteristics. In addition we show that by passing stratigraphic data backward through the filter, certain statistics of surface kinematics from their formative environments can be inferred. Copyright ?? 2011 by the American Geophysical Union.

  12. Drilling and producing offshore

    SciTech Connect

    Hall, R.S.

    1983-01-01

    Hall and his team of authors share technically detailed state-of-the-art designs, equipment and techniques, focusing on fixed-platform operations. This book provides explicit data on offshore equipment and procedures. Contents: Development drilling structures -- template, concrete gravity, and other platforms; Development drilling systems -- through-the-leg drilling, floating drilling, tension-leg platform drilling, template utilization, and mud-line casing suspension and casing support systems; Completion systems -- platform completions, through-the-leg completions, tension-leg completions, multiwell subsea completions, and subsea satellite completion systems; Production control -- wellhead control systems and subsea production control systems; Offshore oil-field diving operations and equipment -- commercial diving, history of diving, international offshore oil-field diving, physiological constraints in diving, diving capabilities and equipment, future trends.

  13. Energy from Offshore Wind: Preprint

    SciTech Connect

    Musial, W.; Butterfield, S.; Ram, B.

    2006-02-01

    This paper provides an overview of the nascent offshore wind energy industry including a status of the commercial offshore industry and the technologies that will be needed for full market development.

  14. Application of soil-stratigraphic techniques to engineering geology

    SciTech Connect

    Shlemon, R.J.

    1985-05-01

    Soil-stratigraphic techniques are being increasingly applied to engineeringgeological investigations for siting liquified natural gas (LNG) facilities, nuclear reactors, dams, and other critical structures. Soil (pedological) profiles in Quaternary sections are useful to ascertain the approximate age of sitearea sediments, to reconstruct local geomorphic history, to date the last movement of faults, and in some cases to determine recurrence intervals of displacements associated with faults or large mass-movements. Exemplified in geotechnical investigations for a proposed LNG terminal near Point Conception (Little Cojo Bay), California, soil stratigraphy was employed to date last displacement of site-area faults, to estimate age of marine platforms, and to help reconstruct regional geomorphic history. Similarly, at the General Electric Test Reactor (GETR) site near Livermore (Vallecitos), California, soil stratigraphy was instrumental to date last displacement and recurrence of site-area slip surfaces engendered either by tectonic or by mass-wasting processes. Datable markers included four, strongly-developed buried paleosols, each of which marked epochs of regional landscape stability during the Quaternary.

  15. Offshore Wind Energy Systems

    ERIC Educational Resources Information Center

    Musgrove, P.

    1978-01-01

    Explores the possibility of installing offshore windmills to provide electricity and to save fuel for the United Kingdom. Favors their deployment in clusters to facilitate supervision and minimize cost. Discusses the power output and the cost involved and urges their quick development. (GA)

  16. QATAR offshore oil

    SciTech Connect

    Not Available

    1980-03-01

    The Qatar Petroleum Producing Authority is presently operating three offshore fields - Idd al-Shargi, Maydan Mahzam and Bul Hanine. The Idd al-Shargi field consists of 14 naturally flowing wells and three suspended wells. Individual flow rates of the producing wells range from 250 to 3000 barrels per day (b/d). The Maydan Mahzam field produces from 11 naturally flowing wells. Reservoir energy in the field is maintained by water injection. Each of the wells produce oil at rates ranging from 2500 to 20,000 b/d. The Bul Hanine field comprises 10 producing wells supported by 9 dumpflooders. Production rates of the individual wells reach 29,000 b/d, making them among the world's highest. In 1978 the completion of a major acceleration project for the Bul Hanine Arab IV reservoir added more than 40,000 b/d to the production potential of the field. Total Qatari oil exports in 1978 were 91,708,000 barrels, equivalent to an average export rate of 25,000 b/d. Total production in Qatar in 1979 was 100,641,394 barrels (offshore) and 84,130,917 (onshore), an increase of 11% and a decrease of 3%, respectively, over 1978. Halal Island provides offshore storage for oil and gas berthing and loading operations. A natural gas liquids offshore complex, including a fractionation plant, is nearing completion at Umm Said. (SAC)

  17. The geotechnical centrifuge in offshore engineering

    SciTech Connect

    Murff, J.D.

    1996-12-31

    One of the greatest needs in offshore geotechnical engineering is for large scale test measurements on which to calibrate design procedures. The geotechnical centrifuge offers at least a partial remedy. Because it allows one to properly simulate stresses, it is a legitimate, relatively inexpensive option to full scale field testing. As such it is a valuable technique and can be an excellent complement to laboratory tests, 1-g model tests and numerical analyses. However, it has not been widely used by industry even though the capability has existed for almost thirty years. This paper argues that this technology should gain acceptance beyond the research community. The paper presents an overview of centrifuge principles, philosophies of use, and limitations of the technique. For illustration, several actual applications of centrifuge testing for complex offshore problems are described. Results are shown to provide important insights into prototype behavior and to agree well with full scale measurements where these are available.

  18. Including stratigraphic hierarchy information in geostatistical simulation: a demonstration study on analogs of alluvial sediments

    NASA Astrophysics Data System (ADS)

    Comunian, Alessandro; Felletti, Fabrizio; Giacobbo, Francesca; Giudici, Mauro; Bersezio, Riccardo

    2015-04-01

    When building a geostatistical model of the hydrofacies distribution in a volume block it is important to include all the relevant available information. Localised information about the observed hydrofacies (hard data) are routinely included in the simulation procedures. Non stationarities in the hydrofacies distribution can be handled by considering auxiliary (soft) data extracted, for example, from the results of geophysical surveys. This piece of information can be included as auxiliary data both in variogram based methods (i.e. co-Kriging) and in multiple-point statistics (MPS) methods. The latter methods allow to formalise some soft knowledge about the considered model of heterogeneity using a training image. However, including information related to the stratigraphic hierarchy in the training image is rarely straightforward. In this work, a methodology to include the information about the stratigraphic hierarchy in the simulation process is formalised and implemented in a MPS framework. The methodology is applied and tested by reconstructing two model blocks of alluvial sediments with an approximate volume of few cubic meters. The external faces of the blocks, exposed in a quarry, were thoroughly mapped and their stratigraphic hierarchy was interpreted in a previous study. The bi-dimensional (2D) maps extracted from the faces, which are used as training images and as hard data, present a vertical trend and complex stratigraphic architectures. The training images and the conditioning data are classified according to the proposed stratigraphic hierarchy, and the hydrofacies codes are grouped to allow a sequence of interleaved binary MPS simulation. Every step of the simulation sequence corresponds to a group of hydrofacies defined in the stratigraphic hierarchy. The blocks simulated with the proposed methodology are compared with blocks simulated with a standard MPS approach. The comparisons are performed on many realisations using connectivity indicators and transport simulations. The latter are performed with the Kolmogorov-Dmitriev method, which allows to investigate the transport behaviour at a spatial scale one order of magnitude bigger than the scale of the model blocks, using the transport properties statistics extracted from the results of particle tracking simulations on the model blocks. To allow a direct comparison with the observed facies maps, which are available in 2D only, all the aforementioned comparison are first performed in 2D and subsequently on the three-dimensional blocks.

  19. Offshore Space Center (offshore launch site)

    NASA Technical Reports Server (NTRS)

    Harvey, D. G.

    1980-01-01

    Any activity requiring the development of the HLLV can benefit by operations from an offshore space center (OSC) since operating near the equator provides a twenty percent increase in payload in an ecliptic plan orbit. Some OSC concepts considered include a moored floating (semisubmersible) design, a stationary design supported by fixed piles, and a combination of these two. The facility supports: a 15,000 foot long, 300 foot wide runway, designed to accommodate a two staged winged launch vehicle, with a one million pound payload capacity to low earth orbit; an industrial area for HLLV maintenance; an airport terminal, control and operation center, and observation tower; liquid hydrogen and liquid oxygen production and storage, and fuel storage platforms; a power generation station, docks with an unloading area; two separate launch sites; and living accommodations for 10,000 people. Potential sites include the Paramount Seamount in the Pacific Ocean off the north coast of South America. Cost estimates are considered.

  20. Geological & Geophysical findings from seismic, well log and core data for marine gas hydrate deposits at the 1st offshore methane hydrate production test site in the eastern Nankai Trough, offshore Japan: An overview

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Noguchi, S.; Takayama, T.; Suzuki, K.; Yamamoto, K.

    2012-12-01

    In order to evaluate productivity of gas from marine gas hydrate by the depressurization method, Japan Oil, Gas and Metals National Corporation is planning to conduct a full-scale production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. The test location was determined using the combination of detailed 3D seismic reflection pattern analysis, high-density velocity analysis, and P-impedance inversion analysis, which were calibrated using well log data obtained in 2004. At the AT1 site, one production well (AT1-P) and two monitoring wells (AT1-MC and MT1) were drilled from February to March 2012, followed by 1 coring well (AT1-C) from June to July 2012. An extensive logging program with logging while drilling (LWD) and wireline-logging tools, such as GeoVISION (resistivity image), EcoScope (neutron/density porosity, mineral spectroscopy etc.), SonicScanner (Advanced Sonic tool), CMR/ProVISION (Nuclear Magnetic Resonance Tools), XPT (formation pressure, fluid mobility), and IsolationScanner (ultrasonic cement evaluation tools) was conducted at AT1-MC well to evaluate physical reservoir properties of gas hydrate-bearing sediments, to determine production test interval in 2013, and to evaluate cement bonding. Methane hydrate concentrated zone (MHCZ) confirmed by the well logging at AT1-MC was thin turbidites (tens of centimeters to few meters) with 60 m of gross thickness, which is composed of lobe type sequences in the upper part of it and channel sand sequences in the lower part. The gross thickness of MHCZ in the well is thicker than previous wells in 2004 (A1, 45 m) located around 150 m northeast, indicating that the prediction given by seismic inversion analysis was reasonable. Well-to-well correlation between AT1-MC and MT1 wells within 40 m distance exhibited that lateral continuity of these sand layers (upper part of reservoir) are fairly good, which representing ideal reservoir for the production test. The XPT measurement results showed approximately 0.1 to several mD of water permeability in both the hydrate-bearing formation and seal formation, although there are some variations in measured values. However, the comparison of these results with permeability estimated by NMR log showed significant discrepancy (more than one order of difference), which suggests that it is necessary to have further investigation considering the difference in scale, measurement direction (Kh or Kv), and calibration methodology by pressure core data. In order to obtain basic reservoir/seal properties for the well log calibration within and above production test interval, pressure coring using Hybrid Pressure Coring System (Hybrid PCS) and also non-destructive core analysis onboard using Pressure Core Analysis and Transfer System (PCATS) were conducted for 60 m interval in AT1-C, which located about 10 m northeast of AT1-MC. Finally, integrated reservoir characterization based on well-log and pressure core data was conducted to predict and optimize the flow rate of upcoming production test.

  1. Lower Jurassic sediments from the Rhar Roubane Mountains (Western Algeria): Stratigraphic precisions and synsedimentary block-faulting

    NASA Astrophysics Data System (ADS)

    Marok, Abbas; Reolid, Matías

    2012-11-01

    During the Lower Jurassic, the stratigraphic and palaeogeographic fluctuations of facies and thickness as well as the existence of stratigraphic gaps in the central and eastern parts of the Rhar Roubane Horst are controlled by the pre-Lower Jurassic palaeotopography as well as the evolution of the subsidence in the different blocks and probably tilting of blocks. This geodynamic context is placed in a general framework of evolution of carbonate rocks of the Tlemcen Domain, characterised by an episode of filling during the Early Pliensbachian followed by a deepening episode from the Late Pliensbachian onward. Four facies associations were recognised through macroscopic and microscopic analyses. Facies association-A corresponds to tidal platform environments, represented by the Zaïlou Limestones Fm. Facies association-B entails biomicrite and biosparite from the shoreface environment represented by the Tisseddoura Limestones Fm in the Central Rhar Roubane Horst and the Pseudonodular Limestones Fm at Eastern Rhar Roubane Horst. Facies association-C comprises a condensed succession rich in ammonoids represented by the Beni Bahdel Ferruginous Limestones Fm, indicating an upper offshore environment. Finally, facies association-D is a marl-limestone rhythmite with abundant cephalopods, corresponding to the Bayada Beds Fm and representing a lower offshore environment. The maximum depth is that of the Toarcian deposits of the Bayada Beds Fm (Area of Tleta). The central part of the Rhar Roubane Horst constituted a topographic barrier that controlled geometry, thickness variation and facies development during the Early Jurassic, evidenced by characteristic deposits with varying thickness and stratigraphic gaps. The Eastern Rhar Roubane Horst reveals such changes in facies, thickness and stratigraphic gaps to be a sedimentary response to the extensional tectonics of tilted blocks. Subsidence in the different areas of the Eastern Rhar Roubane changed during the Pliensbachian to Middle Toarcian, and persistent sectors became subsiding zones or vice versa. A comparison of Rhar Roubane sucessions with neighbouring domains in the Northern Gondwana Palaeomargin, from Morocco to Tunisia, evidences great similarities in the deepening evolution of sedimentation, yet with diachronic platform submergence.

  2. Seismo and sequence stratigraphy of Cenozoic units of the Morondava Basin, offshore western Madagascar

    NASA Astrophysics Data System (ADS)

    Kaufmann, Dirk; Stollhofen, Harald; Klimke, Jennifer; Franke, Dieter

    2015-04-01

    The N-S trending Morondava Basin extends in width from western onshore Madagascar over about 350 km westwards to the offshore Davie Ridge in the Mozambique Channel. Although basin formation was initiated during Karoo times, the main basin evolution took place during Jurassic rifting and subsequent drifting until middle Cretaceous as a result of Gondwana breakup (Geiger et al., 2004). Contemporaneous to the separation of India and Madagascar widespread flood basalts were emplaced during the late Cretaceous (Storey et al., 1995). Present knowledge of the Morondava Basin is mainly based on outcrop studies, seismic surveys and borehole information (e.g. Geiger et al., 2004), gathered in western onshore Madagascar, although the fast majority of the basin, including its depocenter is located offshore in the Mozambique Channel, now at up to 3,500 m water depth. Almost all of the recent offshore studies of the Morondava Basin rely on industrial data but up to date publications of exploration results are generally rare and mostly anonymized. Our study aims to extend knowledge, particularly on the offshore seismic and sequence stratigraphy of the Morondava Basin. A key question is also to test the proposed tectonic stability of the Davie Ridge over the last 40 Ma. For this purpose 12 seismic profiles and bathymetric data, acquired in early 2014 by RV SONNE, are interpreted. Most of the profiles cover the distal deep marine areas of the northern Morondava Basin between the Davie Ridge and the shelf break of Madagascar. Top Cretaceous, Top Eocene, Top Oligocene, the Middle Miocene Unconformity and the Base Pliocene, are mapped as major seismic marker horizons. Especially shelf and slope sedimentary units are important resources to reconstruct the tectonostratigraphic basin evolution. At the continental slope diffuse to chaotic seismic pattern of Miocene and younger age are identified which are subdivided by laterally continuous, high frequency reflectors with a higher impedance contrast. Bounded by the Base Tertiary and the Base Pliocene these units can be used to develop and verify a sequence stratigraphic approach for the Cenozoic in the Morondava Basin. Prelimary results indicate that the major sedimentation at the continental slope moved after Early Pliocene significantly landwards. In general the thickness of post-Pliocene units increases to the east. Work in progress encompasses the application of seismo and sequence stratigraphic concept for Mesozoic sedimentary units and a correlation with other, potentially time-equivalent, basins in the area, such as the Mandawa Basin in northern Mozambique. References Geiger, M., Clark, D.N., und Mette, W., 2004, Reappraisal of the timing of the break-up of Gondwana based on sedimentological und seismic evidence from the Morondava Basin, SW Madagascar: Journal of African Earth Sciences, v. 38, p. 363-381. Storey, M., Mahoney, J. J., Saunders, A. D., Duncan, R. A., Kelley, S. P., und Coffin, M. F., 1995, Timing of Hot Spot--Related Volcanism und the Breakup of Madagascar und India: Science, v. 267, no. 5199, p. 852-855.

  3. Sub-Sea Ice Sands Offshore of Dry Valleys: Potential Links between Onshore and Offshore Cenozoic Records

    NASA Astrophysics Data System (ADS)

    Richardson, T. J.; Miller, M. F.; Bowser, S. S.

    2008-12-01

    Onshore and offshore records of late Cenozoic history of Southern Victoria Land (SVL), Antarctica, depict strikingly different scenarios; onshore (Dry Valleys), the geomorphic record indicates long term (Ma) stability of polar deserts whereas offshore (e.g., ANDRILL 1B), the stratigraphic record reveals repeated ice sheet fluctuations and major cooling and establishment of modern conditions in the Late Pliocene. Recognition of facies deposited beneath near permanent sea ice offshore of the Dry Valleys provides an often overlooked but direct method of connecting the disparate records. As part of an initial effort to document facies characteristics, shallow marine cores >30 cm long were collected from a depth of ~20 m in Explorers Cove at the mouth of the Taylor Dry Valley. Shell material characteristics, bioturbation, grain size distribution, and surface textures of quartz grains were analyzed to elucidate taphonomic processes and sediment transport mechanisms, and to constrain the rate of sedimentation. Little shell material was found in the cores, but foraminifera were widespread and sponge spicules were locally abundant. Some bioturbation is apparent in the top 5 cm, and sediment, primarily medium to coarse sand, is poorly sorted and unlaminated with a coarser zone at 8-21 cm depth. Eolian features are abundant on quartz grain surfaces whereas features indicative of fluvial and glacial transport are less common. Eolian transport probably is the dominant transport process, with sediment blown onto the sea ice and eventually deposited on the sea floor via ice cracks. Small summer streams could also deliver sediment to coastal moats, transporting material beneath the sea ice to deeper nearshore water. Results from this study can be applied to analogous present-day habitats in Antarctica and to the interpretation of Cenozoic stratigraphic sequences in cores.

  4. Polar Layered Deposits: Preliminary Stratigraphic Assessment from MGS Observations

    NASA Technical Reports Server (NTRS)

    Murray, B. C.; Byrne, S.; Danielson, G. E.; Herkenhoff, K. E.; Soderblom, L. A.; Zuber, M. T.

    2000-01-01

    Global and hemispheric climatic, volcanic and impact events that modulated the formation of the Martian polar layered deposits can be revealed by detailed stratigraphic analyses of well-exposed sequences of those layers. Complete three-dimensional Mars Orbiting Laser Altimeter (MOLA) topography of the north and south polar deposits is now available, and very abundant Mars Orbiter Camera (MOC) imagery that is well calibrated is becoming available. This paper presents an assessment of the polar stratigraphic potential based on observations from Mars Global Surveyor (MGS) mapping cycles through M7. Additional information can be found in the original extended abstract.

  5. Arctic offshore platform

    SciTech Connect

    Bhula, D.N.

    1984-01-24

    An offshore structure is disclosed for use in drilling and producing wells in arctic regions having a conical shaped lower portion that extends above the surface of the water and a cylindrical upper section. The conical portion is provided with a controlled stiffness outer surface for withstanding the loads produced by ice striking the structure. The stiffness properties of the outer shell and flexible members are designed to distribute the load and avoid high local loads on the inner parts of the structure.

  6. Lake Michigan Offshore Wind Feasibility Assessment

    SciTech Connect

    Boezaart, Arnold; Edmonson, James; Standridge, Charles; Pervez, Nahid; Desai, Neel; Williams, Bruce; Clark, Aaron; Zeitler, David; Kendall, Scott; Biddanda, Bopi; Steinman, Alan; Klatt, Brian; Gehring, J. L.; Walter, K.; Nordman, Erik E.

    2014-06-30

    The purpose of this project was to conduct the first comprehensive offshore wind assessment over Lake Michigan and to advance the body of knowledge needed to support future commercial wind energy development on the Great Lakes. The project involved evaluation and selection of emerging wind measurement technology and the permitting, installation and operation of the first mid-lake wind assessment meteorological (MET) facilities in Michigan’s Great Lakes. In addition, the project provided the first opportunity to deploy and field test floating LIDAR and Laser Wind Sensor (LWS) technology, and important research related equipment key to the sitting and permitting of future offshore wind energy development in accordance with public participation guidelines established by the Michigan Great Lakes Wind Council (GLOW). The project created opportunities for public dialogue and community education about offshore wind resource management and continued the dialogue to foster Great Lake wind resource utilization consistent with the focus of the GLOW Council. The technology proved to be effective, affordable, mobile, and the methods of data measurement accurate. The public benefited from a substantial increase in knowledge of the wind resources over Lake Michigan and gained insights about the potential environmental impacts of offshore wind turbine placements in the future. The unique first ever hub height wind resource assessment using LWS technology over water and development of related research data along with the permitting, sitting, and deployment of the WindSentinel MET buoy has captured public attention and has helped to increase awareness of the potential of future offshore wind energy development on the Great Lakes. Specifically, this project supported the acquisition and operation of a WindSentinel (WS) MET wind assessment buoy, and associated research for 549 days over multiple years at three locations on Lake Michigan. Four research objectives were defined for the project including to: 1) test and validate floating LIDAR technology; 2) collect and access offshore wind data; 3) detect and measure bird and bat activity over Lake Michigan; 4) conduct an over water sound propagation study; 5) prepare and offer a college course on offshore energy, and; 6) collect other environmental, bathometric, and atmospheric data. Desk-top research was performed to select anchorage sites and to secure permits to deploy the buoy. The project also collected and analyzed data essential to wind industry investment decision-making including: deploying highly mobile floating equipment to gather offshore wind data; correlating offshore wind data with conventional on-shore MET tower data; and performing studies that can contribute to the advancement and deployment of offshore wind technologies. Related activities included: • Siting, permitting, and deploying an offshore floating MET facility; • Validating the accuracy of floating LWS using near shoreline cup anemometer MET instruments; • Assessment of laser pulse technology (LIDAR) capability to establish hub height measurement of wind conditions at multiple locations on Lake Michigan; • Utilizing an extended-season (9-10 month) strategy to collect hub height wind data and weather conditions on Lake Michigan; • Investigation of technology best suited for wireless data transmission from distant offshore structures; • Conducting field-validated sound propagation study for a hypothetical offshore wind farm from shoreline locations; • Identifying the presence or absence of bird and bat species near wind assessment facilities; • Identifying the presence or absence of benthic and pelagic species near wind assessment facilities; All proposed project activities were completed with the following major findings: • Floating Laser Wind Sensors are capable of high quality measurement and recordings of wind resources. The WindSentinel presented no significant operational or statistical limitations in recording wind data technology at a at a high confidence level as compared to traditional anemometer cup technology. • During storms, mean Turbulent Kinetic Energy (TKE) increases with height above water; • Sufficient wind resources exist over Lake Michigan to generate 7,684 kWh of power using a 850 kW rated turbine at elevations between 90 - 125 meters, a height lower than originally anticipated for optimum power generation; • Based on initial assessments, wind characteristics are not significantly different at distant (thirty-two mile) offshore locations as compared to near-shore (six mile) locations; • Significant cost savings can be achieved in generation wind energy at lower turbine heights and locating closer to shore. • Siting must be sufficiently distant from shore to minimize visual impact and to address public sentiment about offshore wind development; • Project results show that birds and bats do frequent the middle of Lake Michigan, bats more so than birds; • Based on the wind resource assessment and depths of Lake Michigan encountered during the project, future turbine placement will most likely need to incorporate floating or anchored technology; • The most appropriate siting of offshore wind energy locations will enable direct routing of transmission cables to existing generating and transmission facilities located along the Michigan shoreline; • Wind turbine noise propagation from a wind energy generating facility at a five mile offshore location will not be audible at the shoreline over normal background sound levels.

  7. Biothems: Sequence stratigraphic units and their implications for regional tectono-stratigraphic interpretations

    SciTech Connect

    Lane, H.R. ); Frye, M.W. ); Couples, G.D. )

    1992-01-01

    Biothems are regional wedge- or lens-shaped bodies of strata that are bounded shelfward or cratonward by paleontologically recognizable unconformities; generally thicken on marine shelves, where they are typically conformable with underlying and overlying biothems; are commonly thinner or represent starved sequences further basinward; and in their most basinward extent, are either bounded by biostratigraphically recognizable unconformities or are conformable with underlying and overlying biothems. As recognized to date, biothems have a logical distribution of faunal and floral components, as well as facies groupings that represent internally consistent and logical sequences of depositional environments. A west-to-east transect within the North American Mississippian System which extends from the Basin and Range Province, across the Transcontinental Arch (TA), into the Anadarko Basin, was constructed to demonstrate the regional distribution and tectono-stratigraphic significance of biothems relative to the axis of the TA. The relationships portrayed on the transect, tied to an understanding of North American Mississippian paleogeography, imply that biothems deposited during relative highstand events on one flank of the TA are time-equivalent to biothems deposited during relative lowstand events on the opposite flank of the TA. This distribution is interpreted to have been controlled by intraplate tectonic events that formed piano key basins along the flanks of the TA. The spatial patterns of these basins are not consistent with published models of basin evolution. A further conclusion is that the lack of coincident, transgressive or regressive Mississippian biothems on either flank of the TA suggests that it is inadvisable to impose the Mississippi Valley-derived eustasy curve on western flank depositional sequences.

  8. Sequential biostratigraphy of the San Jose-1, Puerto Estrella-1, Santa Ana-1, Uashir-1, and Jarara-1 offshore wells, Guajira Peninsula Colombia

    SciTech Connect

    Perez, L. )

    1993-02-01

    Sequence stratigraphical analysis of the San Jose-1, Puerto Estrella-1, Santa Ana-1, Santa Ana-1, Uashir-1, and Jarara-1 offshore wells located in the Portete area, Guajira Peninsula, provide insight into the development and distribution of reservoirs and seals and allows for a finer stratigraphic resolution and correlation than previous available. The sequence stratigraphical interpretation is based on the interpretation of detailed biostratigraphical analysis, the parasequence stacking patterns from the wireline logs, sedimentological data, and seismic stratigraphical interpretation. The Eocene to Pliocene sediments of the Portete wells were deposited for the most part in outer shelf (shelf-slope break) to upper bathyal, disoxic to anoxic environments. Important reservoir development is formed by lowstand slope and basin floor fans interpreted to correspond to the Early Miocene TB1, 1.4 and 1.5, the Middle Miocene TB2 2.3 and 2.4 sequences, and to the Late Eocene to Early Oligocen TA4 supercycle.

  9. Offshore Wind Turbines - Estimated Noise from Offshore Wind Turbine, Monhegan Island, Maine: Environmental Effects of Offshore Wind Energy Development

    SciTech Connect

    Aker, Pamela M.; Jones, Anthony M.; Copping, Andrea E.

    2010-11-23

    Deep C Wind, a consortium headed by the University of Maine will test the first U.S. offshore wind platforms in 2012. In advance of final siting and permitting of the test turbines off Monhegan Island, residents of the island off Maine require reassurance that the noise levels from the test turbines will not disturb them. Pacific Northwest National Laboratory, at the request of the University of Maine, and with the support of the U.S. Department of Energy Wind Program, modeled the acoustic output of the planned test turbines.

  10. Glaucony from the Cretaceous of the Sierra de Guadarrama (Central Spain) and its application in a sequence-stratigraphic context

    NASA Astrophysics Data System (ADS)

    Amorosi, Alessandro; Guidi, Roberto; Mas, Ramon; Falanga, Elisa

    2012-03-01

    Detailed sedimentological and geochemical analyses of Upper Cretaceous glaucony-bearing deposits from the middle portion of the Castro de Fuentiduea Formation, in Central Spain, enable identification of a multiphase history of glaucony accumulation. Despite its relatively high maturity (K2O > 7%), glaucony from the transgressive subtidal sandstones has anomalously low concentration in the host rock (generally <10%), suggesting remobilization from a different source. The remarkable thickness of the glaucony-bearing horizons, concurrently with concentration of glaucony in laminae, small size, and high degree of roundness and sorting provide further evidence for an allochthonous origin of the green grains. In contrast, authigenic glaucony from the overlying offshore clays exhibits higher abundance (up to 45%) and lower maturity (K2O < 7%) and is interpreted to have formed in situ. Allochthonous glaucony originally developed in more distal areas during a prolonged period of sediment starvation. The green grains were then swept away from their place of origin and concentrated into tidal bars and channels within the upper transgressive systems tract of the third-order depositional sequence. Maximum concentration of autochthonous glaucony is recorded at the transition from tidal-influenced to offshore deposits: this glaucony, which is relatively less evolved due to lower time available for maturation, is interpreted to reflect the turnaround from transgressive to highstand conditions, marking the condensed section of the depositional sequence. As postulated by previous sequence-stratigraphic models, this study documents that allochthonous glaucony can be widespread throughout the transgressive systems tract (TST), while the condensed section (CS) typically hosts autochthonous glaucony. Contrary to the existing literature, however, this study shows that glaucony from the TST may be even more mature than glaucony from the CS, if enough time for maturation during transgression is allowed before the ultimate concentration of the green grains. Identification of spatial and temporal characteristics of glaucony, thus, is critical to a reliable sequence-stratigraphic interpretation of the glaucony-bearing deposits.

  11. Stratigraphic framework for Pliocene paleoclimate reconstruction: The correlation conundrum

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.

    2006-01-01

    Pre-Holocene paleoclimate reconstructions face a correlation conundrum because complications inherent in the stratigraphic record impede the development of synchronous reconstruction. The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstructions have carefully balanced temporal resolution and paleoclimate proxy data to achieve a useful and reliable product and are the most comprehensive pre-Pleistocene data sets available for analysis of warmer-than-present climate and for climate modeling experiments. This paper documents the stratigraphic framework for the mid-Pliocene sea surface temperature (SST) reconstruction of the North Atlantic and explores the relationship between stratigraphic/temporal resolution and various paleoceanographic estimates of SST. The magnetobiostratigraphic framework for the PRISM North Atlantic region is constructed from planktic foraminifer, calcareous nannofossil and paleomagnetic reversal events recorded in deep-sea cores and calibrated to age. Planktic foraminifer census data from multiple samples within the mid-Pliocene yield multiple SST estimates for each site. Extracting a single SST value at each site from multiple estimates, given the limitations of the material and stratigraphic resolution, is problematic but necessary for climate model experiments. The PRISM reconstruction, unprecedented in its integration of many different types of data at a focused stratigraphic interval, utilizes a time slab approach and is based on warm peak average temperatures. A greater understanding of the dynamics of the climate system and significant advances in models now mandate more precise, globally distributed yet temporally synchronous SST estimates than are available through averaging techniques. Regardless of the precision used to correlate between sequences within the midd-Pliocene, a truly synoptic reconstruction in the temporal sense is unlikely. SST estimates from multiple proxies promise to further refine paleoclimate reconstructions but must consider the complications associated with each method, what each proxy actually records, and how these different proxies compare in time-averaged samples.

  12. Stratigraphic characterization of the Anthropocene: a progress report

    NASA Astrophysics Data System (ADS)

    Zalasiewicz, Jan

    2014-05-01

    Rapid and large-scale anthropogenic changes have led to the concept that we are now living through the beginning of the Anthropocene Epoch - an interval of geological time dominated by human influence. The term was proposed little more than a decade ago by Paul Crutzen, the Nobel Prize-winning atmospheric chemist, and has since been widely used - and sharply debated. Its stratigraphic analysis needs considering the various kinds of historical and environmental change in terms of geological - or more precisely stratigraphic - change. Lithostratigraphic change, for instance, is strikingly represented by the spread of the 'urban stratum', the refashioning of sand, clay and limestone into our buildings, foundations and transport systems. Biostratigraphic changes include the ongoing mass extinction event and the effect of invasive species (while deep human-made bioturbation is a novel aspect the fossil record). Chemostratigraphic changes include the reshaping of the Earth's natural carbon, phosphorus and nitrogen cycles. As regards the potential formalizing of the Anthropocene, one question to be pursued relates to the chronostratigraphic definition of the phenomena involved: that is, given that many of these transformations are diachronous on human timescales, can an Anthropocene Series, with a synchronous time boundary, be characterized and mapped across the Earth's surface? Efforts to answer this question (Williams et al. 2011; Waters et al., in press) should help in the understanding of the Anthropocene within its geological context, and also in exploring the stratigraphic relation between time and rock generally at very fine stratigraphic timescales. Waters, C.W., Zalasiewicz, J.A., Williams, M., Ellis, M. & Snelling, A. In press. A Stratigraphical Basis for the Anthropocene. Geological Society of London, Special Publication. Williams, M., Zalasiewicz, J., Haywood, A. & Ellis M. (eds) 2011. The Anthropocene: a new epoch of geological time? Philosophical Transactions of the Royal Society 369A, 833-1112.

  13. Sequence-stratigraphic implications of glacial-eustatic Pennsylvanian cyclothems in North America

    SciTech Connect

    Heckel, P.H. . Dept. of Geology)

    1993-02-01

    Only glacial eustasy accounts for all characteristics of Pennsylvanian northern Midcontinent cyclothems that consist of transgressive limestone, offshore ( core') shale, regressive limestone, and variable nearshore to terrestrial shale. Because of the rapidity of glacial eustatic fluctuations of sea level relative to tectonic movements of the shelf or to sediment filling of the large accommodation space provided by sea-level highstand, sequence-stratigraphic concepts and terminology require modification for these cyclothems. It is mainly the condensed intervals of sediment-starved, phosphate- and conodont-rich core shales that represent true highstand deposits on the mid to lower shelf (which is all that is presently preserved). The basic cyclothem was modified in Texas and Illinois by detrital overwhelming of regressive limestone deposition from nearer sources, but similar widespread condensed intervals still represent most of highstand. Higher shelf deposits are preserved in the Appalachian basin where phosphate- glaucony- and conodont-rich Conemaugh marine limestones represent highstand deposits in shallower water. These are penetrated locally eastward by deltaic clastics, which also represent highstand as well as early regression. Later regression involved greater fluvial incision, local terrestrial deposition and widespread paleosol formation, which continued through lowstand and early transgression. Late transgression produced widespread coal swamps, migrating ahead of inundation as a result of rising water table and increasing source of rainfall.

  14. Turbodrilling performance offshore Qatar

    SciTech Connect

    Rana, L.A.; Abdulrahman, E.A.

    1983-03-01

    Until the first quarter of 1979 Qatar General Petroleum Corporation Offshore routinely rotary drilled its vertical development wells using tricone bits. Turbodrilling the 17 1/2'' and 8 1/2'' hole sections was introduced in the second quarter of 1979 followed by the 12 1/4'' hole section in the first qarter of 1980. This resulted in avoiding/minimising downhole problems and the elimination of 7'' and 4 1/2'' liners. As a result of introducing these practices a 50 percent time saving and a 30 percent cost saving has been achieved, equivalent to $550,000/well.

  15. Quality assurance for offshore aluminum sacrificial anodes

    SciTech Connect

    Britton, J. )

    1993-10-01

    In recent years there has been a far greater emphasis placed on quality assurance within the oil and gas industry, including the cathodic protection supply sector within the offshore market. The need for quality aluminum anodes is obvious, especially for deep-water projects. This trend toward improved quality control has resulted in more third-party inspection work and better-defined quality test procedures. The practicalities of quality control and some of the problems encountered are highlighted.

  16. Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    Fraser, A.J.; Matthews, S.J.; Lowe, S.; Todd, S.P.; Simon, P. Peel, F.J. )

    1996-01-01

    Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motions have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.

  17. Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    Fraser, A.J.; Matthews, S.J.; Lowe, S.; Todd, S.P.; Simon, P. Peel, F.J.

    1996-12-31

    Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motions have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.

  18. Offshore outlook: the American Arctic

    SciTech Connect

    Jahns, M.O.

    1985-05-01

    Offshore areas in the American Arctic are highlighted and the development of the area is compared with other offshore areas where the required technology is more readily available. Principal areas are shown in which new concepts are being put to practice. Canada's east coast is examined. Several technological trends are reviewed to help operators accelerate the discovery and development of arctic petroleum reserves.

  19. Challenges and Opportunities in Geomorphic-Stratigraphic Linkages

    NASA Astrophysics Data System (ADS)

    Burbank, D. W.

    2012-12-01

    Whereas geomorphic processes undeniably modulate the depositional sequences that constitute the stratigraphic record, a discrete geomorphic imprint is commonly difficult to discern in ancient sediments. Part of this disconnect results from the characteristics of typical study sites. Many geomorphic studies are conducted in terrain, i.e., mountains, that is degrading via long-term erosion, such that (i) the preservation potential of the geomorphic-depositional record is negligible and (ii) the geomorphic processes may be distinctly different from those in depositional basins. Both the disparate time scales of observation and the differing preservation tendencies of sedimentologic events in the geomorphic versus stratigraphic record also inhibit development of unambiguous linkages between them. Even some spectacularly clear stratigraphic records of deformation, such as those evinced by growth strata, may be very subtle in a modern geomorphic setting as they are being formed. To the extent that large-scale, "catastrophic" geomorphic events significantly influence the stratigraphic record, the infrequency of such events dictates that relevant geomorphic observations of them are commonly sparse. Despite these difficulties, improved understanding of geomorphic-stratigraphic connections are emerging from several perspectives. Geomorphic studies at the surface of actively aggrading basins provide modern depositional analogues. The ever-growing imagery archive available via Google Earth permits increasingly detailed reconstructions of the evolution of geomorphic and depositional systems in sites of ongoing sediment preservation in actively subsiding basins. Repeat LiDAR imaging provides quantification of channel geometries, incision, and deposition at time scales ranging from single events to decadal scales. Analogue models in which subsidence, base level, discharge, sediment supply can be controlled provide insights on the interplay between variables that modulates depositional patterns. In modern sites with high preservation potential, knowledge of the commonly changing geomorphic mosaic of local erosion and aggradation through space and time is key to reliable interpretations of the ancient record of depositional and erosional events, changing environmental conditions, and unconformities and sequence boundaries that together make up the temporally incomplete, composite stratigraphic sections that typify the sedimentary record.

  20. An alternative stratigraphic scheme for the Sarawak Basin

    NASA Astrophysics Data System (ADS)

    Mat-Zin, I. C.; Tucker, M. E.

    1999-04-01

    The present stratigraphic scheme for the Tertiary of Sarawak (Ho, K.F., 1978. Stratigraphic framework for oil exploration in Sarawak. Bulletin of the Geological Society of Malaysia, 10, 1-14), which subdivides the entire sedimentary succession into eight sedimentary cycles, is based on the genetic sedimentary cycle concept. Each cycle starts with a transgressive basal part, followed by a regressive unit, which is in turn overlain by the basal transgressive unit of the next cycle. The limitation of the present scheme is, however, in its general applicability; for instance, when one tries to identify the equivalents of marine surfaces within non-marine sediments. This is critical for some areas in Sarawak where the sediments were deposited predominantly within lower coastal plain to upper coastal plain environments, normally barren of foraminifera. Among other inadequacies of the scheme is the lack of basin-wide association between the cycle boundaries and seismic reflectors. In practice cycle boundaries, picked on the composite well logs, often do not agree with the seismic pick. The scheme is, however, well accepted and continues to be used. The alternative stratigraphic scheme for the Sarawak Basin, which will be discussed in this paper, is based on sequence stratigraphic concepts, with the utilisation of unconformity or its correlative conformity as the stratigraphic boundary. This scheme has been generated as the result of a programme of basin-wide seismic mapping of the Sarawak Basin. Seven regional unconformities within the Tertiary sedimentary sequences have been mapped. The sedimentary units between the unconformities can be recognised as 'Sequences'. The oldest unconformity is that between the basement (Belaga Formation) and the overlying Tertiary sediments, mainly of Late Oligocene age. Since the sediments in the basin are mainly of Tertiary age, the oldest unit of the succession is referred to as the Tertiary One Sequence (T1 S). The next younger sequence is called Tertiary Two Sequence (T2 S) and so on. The proposed scheme, which is based on a more conventional and multi-disciplinary approach, can be understood and appreciated, not only by palaeontologists, but by all members of exploration and production teams. The scheme should be able to facilitate prediction of stratigraphic levels, not only after the well has been drilled, but also prior to drilling.

  1. Towers for Offshore Wind Turbines

    NASA Astrophysics Data System (ADS)

    Kurian, V. J.; Narayanan, S. P.; Ganapathy, C.

    2010-06-01

    Increasing energy demand coupled with pollution free production of energy has found a viable solution in wind energy. Land based windmills have been utilized for power generation for more than two thousand years. In modern times wind generated power has become popular in many countries. Offshore wind turbines are being used in a number of countries to tap the energy from wind over the oceans and convert to electric energy. The advantages of offshore wind turbines as compared to land are that offshore winds flow at higher speed than onshore winds and the more available space. In some land based settings, for better efficiency, turbines are separated as much as 10 rotor diameters from each other. In offshore applications where only two wind directions are likely to predominate, the distances between the turbines arranged in a line can be shortened to as little as two or four rotor diameters. Today, more than a dozen offshore European wind facilities with turbine ratings of 450 kw to 3.6 MW exist offshore in very shallow waters of 5 to 12 m. Compared to onshore wind turbines, offshore wind turbines are bigger and the tower height in offshore are in the range of 60 to 80 m. The water depths in oceans where offshore turbines can be located are within 30 m. However as the distance from land increases, the costs of building and maintaining the turbines and transmitting the power back to shore also increase sharply. The objective of this paper is to review the parameters of design for the maximum efficiency of offshore wind turbines and to develop types offshore towers to support the wind turbines. The methodology of design of offshore towers to support the wind turbine would be given and the environmental loads for the design of the towers would be calculated for specific cases. The marine corrosion on the towers and the methods to control the corrosion also would be briefly presented. As the wind speeds tend to increase with distance from the shore, turbines build father offshore will be able to capture more wind energy. Currently two types of towers are considered. Cylindrical tubular structures and truss type structures. But truss type structures have less weight and flexibility in design. The construction of the offshore towers to harness the wind energy is also presented. The results will include the calculation of wind and wave forces on the tower and the design details for the tower.

  2. Floating offshore structure

    SciTech Connect

    Oshima, M.; Narita, H.; Tabuchi, H.; Yashima, N.

    1985-05-28

    A floating offshore structure which is moored at a fixed position on the sea by means of mooring hawsers and anchors connected to the ends thereof respectively for conducting a submarine excavating operation from a deck of the structure. The structure includes a moorage hull part provided with a vertical through-hole formed therein for receiving an excavating drill pipe and the mooring hawsers and a movable hull part connected to the moorage hull part so as to be rotatable within a horizontal plane. The movable hull part is constituted as a hull defining the outer wall of the floating offshore structure and connected with the moorage hull part by inserting it into a moorage hull part receiving hole formed at a position closer to the bow thereof. The movable hull part has near its water plane a horizontal section with a substantially oval shape formed by a fore draft part in a substantially circular or polygonal shape, with the moorage hull part receiving hole as a center and an after draft part taperingly projecting aft from the fore draft part.

  3. Pioneering offshore excellence

    SciTech Connect

    Kent, R.P.; Grattan, L.

    1996-11-01

    Hibernia Management and Development Company Ltd. (HMDC) was formed in 1990 by a consortium of oil companies to develop their interests in the Hibernia and Avalon reservoirs offshore Newfoundland in a safe and environmentally responsible manner. The reservoirs are located 315km ESE of St. John`s in the North Atlantic. The water depth is about 80m. The entire Hibernia field is estimated to contain more than three billion barrels of oil in place and the owners development plan area is estimated to contain two billion barrels. Recoverable reserves are estimated to be approximately 615 million barrels. The Hibernia reservoir, the principle reservoir, is located at an average depth of 3,700m. HMDC is building a large concrete gravity based structure (GBS) that which will support the platform drilling and processing facilities and living quarters for 280 personnel. In 1997 the platform will be towed to the production site and production will commence late 1997. Oil will be exported by a 2 km long pipeline to an offshore loading system. Dynamically positioned tankers will then take the oil to market. Average daily production is expected to plateau between 125,000 and 135,000 BOPD. It will be the first major development on the east coast of Canada and is located in an area that is prone to pack ice and icebergs.

  4. Application of nonmarine genetic sequence stratigraphic concepts to reservoir characterization in the fluvial-lacustrine Westbourne Formation, Eromanga basin, Australia

    SciTech Connect

    Hamilton, D.S.; Holtz, M.H.; Yeh, J. )

    1996-01-01

    A high-resolution sequence stratigraphic analysis of the Westbourne Formation identified five chronostratigraphic genetic units each separated by thin, but laterally extensive, shale markers interpreted as maximum lacustrine flooding surfaces. The flooding surfaces were primarily identified by their lateral persistence and high gamma-ray log response, but marked changes in bedding architecture across these surfaces also facilitated their identification. The changes in bedding architecture reflect reorganization of the depositional systems from one depositional episode to the next. The Westbourne Formation is interpreted as a series of fluvially-dominated lacustrine delta sequences. Although the genetic units generally display lobate to digitate sand body geometries, sediment transport directions between successive units is highly variable. The complex morphology of the distributary network and accompanying high degree of facies variability indicates shallow lacustrine sedimentation similar to that in the modern inland Niger River delta which provides a modern analog. Westbourne fluid flow trends were established by mapping water encroachment during field development, observing differential depletion in repeat formation test data, and monitoring production response to water shut-off workovers. The fluid flow trends emphasized the highly layered character of the Westbourne reservoirs and integrating these trends with the geologic architecture defined stratigraphic controls on Westbourne flow units. The stratigraphic framework proved essential for unraveling sediment transport patterns and thus, predicting reservoir sandstone distribution. The stratigraphic framework also provided the key to understanding water encroachment and pressure a depletion which, when combined with predicted sandstone geometries, identified several step-out drilling and recompletion opportunities.

  5. Application of nonmarine genetic sequence stratigraphic concepts to reservoir characterization in the fluvial-lacustrine Westbourne Formation, Eromanga basin, Australia

    SciTech Connect

    Hamilton, D.S.; Holtz, M.H.; Yeh, J.

    1996-12-31

    A high-resolution sequence stratigraphic analysis of the Westbourne Formation identified five chronostratigraphic genetic units each separated by thin, but laterally extensive, shale markers interpreted as maximum lacustrine flooding surfaces. The flooding surfaces were primarily identified by their lateral persistence and high gamma-ray log response, but marked changes in bedding architecture across these surfaces also facilitated their identification. The changes in bedding architecture reflect reorganization of the depositional systems from one depositional episode to the next. The Westbourne Formation is interpreted as a series of fluvially-dominated lacustrine delta sequences. Although the genetic units generally display lobate to digitate sand body geometries, sediment transport directions between successive units is highly variable. The complex morphology of the distributary network and accompanying high degree of facies variability indicates shallow lacustrine sedimentation similar to that in the modern inland Niger River delta which provides a modern analog. Westbourne fluid flow trends were established by mapping water encroachment during field development, observing differential depletion in repeat formation test data, and monitoring production response to water shut-off workovers. The fluid flow trends emphasized the highly layered character of the Westbourne reservoirs and integrating these trends with the geologic architecture defined stratigraphic controls on Westbourne flow units. The stratigraphic framework proved essential for unraveling sediment transport patterns and thus, predicting reservoir sandstone distribution. The stratigraphic framework also provided the key to understanding water encroachment and pressure a depletion which, when combined with predicted sandstone geometries, identified several step-out drilling and recompletion opportunities.

  6. OUTSHORE Maturity Model: Assistance for Software Offshore Outsourcing Decisions

    NASA Astrophysics Data System (ADS)

    Mki, Juho; Betz, Stafanie; Oberweis, Andreas

    Offshore outsourcing software development (OOSD) is increasingly being used by the Software Industry. OOSD is a specific variant of Geographically Distributed Software Developmentdistributed software development (GDSD). Compared to the traditional mode of software development (i.e., in-house) GDSD is more edgy and puts at risk the attainment of the expected results. Although the failure of an offshore outsourcing software project may be caused by a variety of factors, one major complication is geographical distance. Consequently we argue that risk avoidance in outshore software development should be undertaken well in advance of the development launch. This could be done by testing the offshore outsourcing relevance of each software project and then the offshore outsourcing company involved. With this in mind we have developed the OUTSHORE Maturity Modeloutshore maturity model - OMM.

  7. Stratigraphic record of Holocene coseismic subsidence, Padang, West Sumatra

    NASA Astrophysics Data System (ADS)

    Dura, Tina; Rubin, Charles M.; Kelsey, Harvey M.; Horton, Benjamin P.; Hawkes, Andrea; Vane, Christopher H.; Daryono, Mudrik; Pre, Candace Grand; Ladinsky, Tyler; Bradley, Sarah

    2011-11-01

    Stratigraphic evidence is found for two coseismic subsidence events that underlie a floodplain 20 km south of Padang, West Sumatra along the Mentawai segment (0.5S-0.3S) of the Sunda subduction zone. Each earthquake is marked by a sharp soil-mud contact that represents a sudden change from mangrove to tidal flat. The earthquakes occurred about 4000 and 3000 cal years B.P. based on radiocarbon ages of detrital plant fragments and seeds. The absence of younger paleoseismic evidence suggests that late Holocene relative sea level fall left the floodplain too high for an earthquake to lower it into the intertidal zone. Our results point to a brief, few thousand year window of preservation of subsidence events in tidal-wetland stratigraphic sequences, a result that is generally applicable to other emergent coastlines of West Sumatra.

  8. The Anthropocene is functionally and stratigraphically distinct from the Holocene.

    PubMed

    Waters, Colin N; Zalasiewicz, Jan; Summerhayes, Colin; Barnosky, Anthony D; Poirier, Clément; Gałuszka, Agnieszka; Cearreta, Alejandro; Edgeworth, Matt; Ellis, Erle C; Ellis, Michael; Jeandel, Catherine; Leinfelder, Reinhold; McNeill, J R; Richter, Daniel deB; Steffen, Will; Syvitski, James; Vidas, Davor; Wagreich, Michael; Williams, Mark; Zhisheng, An; Grinevald, Jacques; Odada, Eric; Oreskes, Naomi; Wolfe, Alexander P

    2016-01-01

    Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs. PMID:26744408

  9. Tectono-stratigraphic interpretation, DBGS-114, Delaware Basin

    SciTech Connect

    Swift, D.B.; Reeves, J.J.

    1995-06-01

    Reprocessing and seismic sequence interpretation of Delaware Basin Group Shoot Line 114 suggests a complex interacting stratigraphic and tectonic history within the Delaware Basin and its margins. A total of 43 sequence stratigraphic intervals have been identified along a 30 mile portion of 114 made available for investigation. Clastic sequence packages interfinger locally with other sediments, being shed basinward from both the Diablo and Central Basin Platforms. Numerous sequences thus display nondepositional or erosional hiatuses. Local channels or lensoidal-like reflection configurations are present throughout the section, from Rustler through Lower Pennsylvanian Formations. These features are predominant within the deeper parts of the Basin and decrease in number towards the basin margins. Only one such body was encountered on the Diablo Platform whereas over two dozen were observed within the basin proper. These features may represent clastic and/or carbonate debris flows which moved laterally away from the basin margins to eventually flow parallel to the basin axis. Variations in amplitude and reflection continuity suggest lateral changes in rock type from shaly to more sand or carbonate rich lithologies. This interpretation is locally supported by well and sample logs which reflect this lithologic variation. Evidence for Permian-Pennsylvanian and older pre-Woodford tectonic activity is also suggested across the entire Delaware Basin from the stratigraphic intervals affected by faulting. High- and low-angle reverse and up-to-the-basin faults strongly suggest a tectonic event of about pre-Woodford age. Some of these faults may have been reactivated during the major Permo-Penn tectonic event which deformed the Permian Basin. Understanding the complex tectono-stratigraphic history of the region may be the key to unlocking new, undiscovered domestic oil and gas reserves within the Delaware Basin.

  10. Paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks

    SciTech Connect

    Cecil, C.B. )

    1990-06-01

    Climate is a primary control on sediment flux from continental sources into sedimentary systems. In warm climates, siliciclastic input is greatest under highly seasonal rainfall. Nonseasonal conditions favor formation of end member chemical rocks; perennially wet climates are conductive to coal formation, whereas dry climates produce carbonates and/or evaporites. Stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive-regressive events and tectonics.

  11. Antarctic Drilling Recovers Stratigraphic Records From the Continental Margin

    NASA Astrophysics Data System (ADS)

    Harwood, David; Florindo, Fabio; Talarico, Franco; Levy, Richard; Kuhn, Gerhard; Naish, Tim; Niessen, Frank; Powell, Ross; Pyne, Alex; Wilson, Gary

    2009-03-01

    The Antarctic Geological Drilling (ANDRILL) programa collaboration between Germany, Italy, New Zealand, and the United States that is one of the larger programs endorsed by the International Polar Year (IPY; http://www.ipy.org)-successfully completed the drilling phase of the Southern McMurdo Sound (SMS) Project in December 2007. This second drill core of the program's campaign in the western Ross Sea, Antarctica, complements the results of the first drilling season [Naish et al., 2007] by penetrating deeper into the stratigraphic section in the Victoria Land Basin and extending the recovered time interval back to approximately 20 million years ago. The primary objectives of ANDRILL (http://www.andrill.org/) were to recover stratigraphic records from the Antarctic continental margin that document key steps in Antarcticas Cenozoic (0- to 65-million-year-old) climatic and glacial history, and in the tectonic evolution of the Transantarctic Mountains and the West Antarctic Rift System [Harwood et al., 2006]. These two ANDRILL stratigraphic drill cores are guiding the understanding of the speed, size, and frequency of the past 20 million years of glacial and interglacial changes in the Antarctic region. The drill cores will help to establish, through their correlation to existing records and their integration with climate and ice sheet models, how these local changes relate to regional and global events.

  12. Improved seismic stratigraphic interpretation with VSPs and well logs

    SciTech Connect

    Poster, C.K.

    1987-05-01

    The addition of Vertical Seismic Profiles (VSPs) and well logs to coinciding surface seismic data improves resolution and interpretation away from the well, of formations encountered at the well. The positioning of further delineation wells, the interpretation of stratigraphy between wells, and the interpretation of stratigraphic changes near a well, benefit from the rigorous use of these data. The VSP, when parallel-processed with the surface seismic data, accurately indicates the location in time of the well on the seismic section, both laterally and vertically. The VSP also permits the time-scaling of the log data to match the seismic data. Thorough interpretation of these logs produces formational models, which include in situ lithology, porosity, hydrocarbon distribution, and the zoned reflectivity corresponding to formation boundaries. This reflectivity is used to estimate a wavelet filter from the seismic data, which, combined with the log's reflectivity and the measured relationship of acoustic impedance to porosity, permits accurate modeling of stratigraphic changes away from the well. The wavelet can also be used to compute zero-phase filters for improving the resolution of seismic reflections near the well. The use and interpretation of a complex trace attributes, envelope and instantaneous phase, is seen to be improved after zero-phasing. Examples from major reservoirs in the Middle East, including the Mishrif reefs and other carbonate formations, illustrate the reconciliation of log and seismic data and improved stratigraphic interpretation between wells.

  13. Revision and update of the stratigraphic nomenclature of Netherlands

    SciTech Connect

    Van Adrichem Boogaert, A. ); Kouwe, W. )

    1993-09-01

    In 1991, the Geological Survey of the Netherlands started a project for revision and updating of the pre-Quaternary lithostratigraphy of Netherlands. This had not been done systematically since 1980. Main objective of the study are (1) to bring the lithostratigraphic ideas into agreement with new findings and increased knowledge of Dutch subsurface geology (lithostratigraphy was extended into the Lower Carboniferous and Devonian), (2) expansion and standardization of the definitions and descriptions of existing lithostratigraphic units, (3) application of modern concepts (e.g. sequence stratigraphy) in order to describe better the distribution of reservoir-prone sediments, and (4) to reach consensus on a number of stratigraphy-related subjects, such as a chronological time frame, application of biozonations, and the designation of the behavior of main structural elements through time. Eight working groups were formed, each working on a specific aspect or stratigraphic interval, under the supervision of a steering committee. Both working groups and steering committee were composed of persons from the Geological Survey, several leading oil companies and, in some cases, universities. Several working groups have completed their tasks, and updates of these stratigraphic intervals are available at the conference. Posters will display stratigraphic updates of lithostratigraphy for the Carboniferous, Zechstein, Lower Triassic, and Upper Jurassic-Lower Cretaceous.

  14. U.S. Geological Survey program of offshore resource and geoenvironmental studies, Atlantic-Gulf of Mexico region, from September 1, 1976, to December 31, 1978

    USGS Publications Warehouse

    Folger, David W.; Needell, Sally W.

    1983-01-01

    Mineral and energy resources of the continental margins of the United States arc important to the Nation's commodity independence and to its balance of payments. These resources are being studied along the continental margins of the Atlantic Ocean and the Gulf of Mexico in keeping with the mission of the U.S. Geological Survey to survey the geologic structures, mineral resources, and products of the national domain.'(Organic Act of 1879). An essential corollary to these resource studies is the study of potential geologic hazards that may be associated with offshore resource exploration and exploitation. In cooperation with the U.S. Bureau of Land Management, the Geological Survey, through its Atlantic-Gulf of Mexico Marine Geology Program, carries out extensive research to evaluate hazards from sediment mobility, shallow gas, and slumping and to acquire information on the distribution and concentration of trace metals and biogenic and petroleum-derived hydrocarbons in sea-floor sediments. All these studies arc providing needed background information, including information on pollutant dispersal, on the nearshore, estuarine, and lacustrine areas that may be near pipeline and nuclear powerplant sites. Users of these data include the Congress, many Federal agencies, the coastal States, private industry, academia, and the concerned public. The results of the regional structural, stratigraphic, and resource studies carried out under the Atlantic-Gulf of Mexico Marine Geology Program have been used by the Geological Survey and the Bureau of Land Management to select areas for future leasing and to aid in the evaluation of tracts nominated for leasing. Resource studies have concentrated mostly on the Atlantic Outer Continental Shelf frontier areas. Geologic detailing of five major basins along the U.S. Atlantic margin, where sediments are as much as 14 km thick, have been revealed by 25,000 km of 24-and 48-channel common-depth-point seismic data, 187,000 km of acromagnetic data, and 39,000 km of gravity data, plus 10,000 samples and logs obtained from U.S. Geological Survey and industry drilling (for example, coreholes of the Atlantic Slope Program, Joint Oceanographic Institutions Deep Earth Sampling, Continental Offshore Stratigraphic Tests, and the Atlantic Margin Coring Program). A sedimentary section of Jurassic and Cretaceous age grades from terrigenous clastic rocks nearshore to carbonate rocks offshore; this section is part of an extensive buried bank-platform complex that could contain large reserves of natural gas and oil. The volume of sediment deposited offshore far exceeds the volume deposited onshore where extensive accumulations of oil, gas, and minerals have been found. Commercial exploratory drilling offshore thus far has been limited to the Baltimore Canyon Trough area off New Jersey, where at least two holes have found gas; leasing has taken place in the Southeast Georgia Embayment, where drilling was scheduled to begin in 1979, and is imminent in the Georges Bank area off New England. In addition, hydrogeologic and hydrochemical data obtained from the drilling studies have delineated freshwater-bearing submarine extensions of land aquifers that are important coastal ground-water resources. Hazards in the Georges Bank area include sand mobility associated with strong currents and storm-driven waves; high concentrations of suspended sediment in the water column that, when mixed with spilled oil, may sink to the bottom; and slumping along the upper slope. In the Baltimore Canyon, high sediment mobility accompanies major winter storms, and slumped material may cover as much as 20 percent of the upper slope. Potentially unstable slope areas are being studied in great detail to provide data on timing, triggering mechanisms, and rates of sediment movement. In the Southeast Georgia Embayment and Blake Plateau Basin, strong Gulf Stream flow poses a major problem to all offshore operations. In the Gulf o

  15. Bahrain's offshore banking center

    SciTech Connect

    Gerakis, A.S.; Roncesvalles, O.

    1983-01-01

    The economic effects of Bahrain's schemes for licensing offshore banking units (OBUs) were the immediate response of major international banks and the financial services the banking center has rendered by improving regional money and exchange markets at a time when a Middle East link was needed to service the increasing demand for oil-wealth banking services. Bahrain's leadership also created a favorable climate. Aggressive competition from banks in Kuwait and Saudi Arabia have caused some friction, but informal supervision by the Bahrain Monetary Agency (BMA) should be able to avoid serious difficulty. Bahrain's success required a banking infrastructure, a free-enterprise system, a willingness to maintain banking standards, a country small enough to benefit directly from OBU income, and a gap in nearby competing centers. 39 references, 1 figure, 5 tables. (DCK)

  16. Offshore well casing cathodic protection

    SciTech Connect

    Hamberg, A.; Orton, M.D.; Smith, S.N.

    1987-01-01

    Many papers have been published on cathodic protection of offshore platforms, but few references are made on the extent of protection of the well casings attached to the structures. Others reported tests in the Arabian Gulf which showed the galvanic anodes protected the wells to a depth of approximately 3200 ft (976 m) and that 300 A were required to completely protect bare well casings attached to a six-well platform in 40 ft (12 m) of water. Recent tests in deeper water (170 ft (52 m() showed the structure galvanic anodes deliver approximately 8 A per well and protect the bare casing to approximately 3000 ft (915 m). An impressed current cathodic protection system with 600 A applied to anodes placed 400 ft (122 m) from the structure protected the structure and six bare well casings to 8000 ft (2440 m). A protection criterion of 0.1 mA/ft/sup 2/ (1.1 mA/m/sup 2/) in the lower cemented zone was proposed. Impressed current anodes placed closer than 400 ft (122 m) from the structure did not protect the wells to the required depth.

  17. Paleomagnetic constrains in the reconstruction of the recent stratigraphic evolution of the Po delta

    NASA Astrophysics Data System (ADS)

    Correggiari, Annamaria; Vigliotti, Luigi; Remia, Alessandro; Perini, Luisa; Calabrese, Lorenzo; Luciani, Paolo

    2014-05-01

    The delta and prodelta deposits are characterized by a complex stratigraphic architecture that can be approached with several multidisciplinary tools. We present an example from the Po delta system characterized by alternating phases of rapid advance and abandonment of its multiple deltaic lobes that has been investigated through: (1) a review of historical cartography extending back several centuries; (2) integrated surveys of VHR seismic profiles recorded offshore of the modern delta from water depths as shallow as 5 m to the toe of the prodelta in about 30 m; and (3) sedimentological and geochronological data from precisely positioned sediment cores. Within this well known stratigraphic framework we have acquired seismic data and sediment cores in the area of the post roman Po delta system. However a precise dating of the recent evolution of depositional delta lobes is difficult because of the lack of suitable dating methods. To constrain the emplacement timing of the Renaissance lobes a paleomagnetic studies was carried out on a sedimentary sequence representing a seismic facies well correlated in the cores by whole core magnetic susceptibility profile. Forty eight samples were collected from a core section (RER96-1) characterized by a fine grained lithology suitable for paleomagnetic investigations. The characteristic remanent magnetization (ChRM) of the sediments has been obtained by applying an AF cleaning between 10 and 30 millitesla. The results have been compared with the directions recorded by the historical lavas of the Etna and Vesuvius. The combination of the trends observed in the declination and inclination suggests that the results can be compatible with the directions of the secular variation of the earth magnetic field occurring during the XVII century. This allow to date the sismic unit as representative of the beginning of the new delta following the Porto Viro avulsion made by the Venice Republic in 1604 AD. This delta history reflects the forcing of high-frequency climate change, autocyclic avulsions, and anthropogenic factors, acting on variable, but typically short, time scales. By using multidisciplinary methods of investigation is possible to detect the sedimentary response forced by anthropic impact at centennial/decadal time scale.

  18. Stratigraphical links between Miocene Alpine Foreland basin and Gulf of Lion Passive Margin during lowstands

    NASA Astrophysics Data System (ADS)

    Rubino, Jean-Loup; Gorini, Christian; Leroux, Estelle; Aslanian, Daniel; Rabineau, Marina; Parize, Olivier; Besson, David

    2015-04-01

    Miocene peri-alpine foreland basin is connected toward the south with the Gulf of Lion passive margin and is predominantly filled by marine shallow water molassic deposits ranging from lower Miocene to Pliocene in age. Nine to ten depositional sequences are recorded and partly preserved in this basin and can be traced into the post rift part of the Gulf of Lion. One of the most surprising feature of the stratigraphic infill is the total lack of lowstand deposits within the foreland basin ; All superimposed sequences only includes transgressive and highstand System Tracts separated by erosional sequence boundaries and the development of incised valley networks filled by tidal deposits during transgression; Besson et al. 2005. It means that the entire foreland basin in SE France is exposed during lowstand periods without any preservation of fluvial deposits. By place few forced regression wedges are preserved at the transition between the foreland and the passive margin, close to the present day coastline. To date no real lowstand wedges have never been reported in the offshore of the Gulf of Lion. A reinterpretation of the best old vintage 2D dip seismic profiles along the passive margin validates the idea that the foreland basin is entirely exposed as well as the proximal part of the passive margin; first because some incised valleys can be occasionally picked on the shelf and second mainly because well defined superimposed or juxtaposed prograding lowstand wedges with nicely defined clinoforms onlapping the sequence boundaries can be recognized on the distal part of the shelf from the Burdigalian to the Messinian. Their ages being constrains by the Calmar well calibration. Unfortunately, they can't be continuously mapped all along the shelf break because of the strong erosion related to the Messinian Unconformity and the associated huge sea level fall.So we have to explain why during the lowstands, exceptionally long fluvial valley networks (more than 300km) can be developed. The first observation shows that the subsidence rate at least in the marginal part of the foreland basin, close to the forebulge, along the Rhone Valley, is very low and never exceed 40m/My. Second, the water depth of the deeper shelf series doesn't go deeper than 70 - 80m with shallowest water depth in the thresholds separating sub-basins. Therefore eustatically driven Miocene sea level changes can probably be great enough during this stratigraphic interval (50 to 70m) to lead to the almost complete basin emergence. Finally fluvial over-incision could also be enhanced by tectonic uplift links to anticline growing or local diapirism.

  19. New structural and stratigraphic interpretation of Lake Superior basin from hydrocarbon exploration geophysics and geology

    SciTech Connect

    Dickas, A.B.

    1996-09-01

    Between October 1987 and April 1992, two deep boreholes were drilled along the south shore of Lake Superior in a test of the hydrocarbon potential of the conglomerate, sandstone and shale composing the Middle Proterozoic Oronto Group ({approximately}1 billion years). These drilling ventures, preceded by geophysical programs, and combined with wireline and core information, support new interpretations of the structural and stratigraphic geology associated with the Midcontinent Rift System in the Lake Superior district. No.7-22 Terra-Patrick: A stratigraphic, but not structural fit. This borehole in Bayfield County, Wisconsin, drilled an expected sequence of Oronto Group clastic redbeds. No viable hydrocarbon shows were encountered. Six second reflection seismology profiles collected in northwestern Wisconsin indicate the Douglas Fault decreases in throw in an easterly direction, changing to a fold northeast of the borehole. This termination is associated with the south flank of White`s Ridge, a pre-rift residual high identified through modeling studies and seismic interpretations by local absence of Midcontinent Rift volcanics and overlying strata. To the southwest of Isle Royale, the pre-rift Grand Marias Ridge exhibits similar characteristics. No.1-29 St. Amour: A structural, but not stratigraphic, fit. Drilled in Alger County, Michigan, the St. Amour well appears to bottom in pre-rift metamorphic basement rocks. This hole was 100% cored. No hydrocarbon shows were reported. Reflection seismology profile analyses verify a change in strike, from northeast to southeast, of the Keweenaw Fault in the eastern Lake Superior Basin. The drilled section included 6,000 feet of pre-Paleozoic red-beds containing cross-bedding, ripple marks, and multiple fining-upward strata.

  20. Methane Seeps along Offshore Virginia

    USGS Multimedia Gallery

    Numerous distinct methane streams emanating from the seafloor at an upper slope (< 500 m water depth) cold seep site offshore Virginia. Image courtesy of NOAA Okeanos Explorer Program, 2013 Northeast U.S. Canyons Expedition....

  1. Seismic lateral prediction in chalky limestone reservoirs offshore Qatar

    SciTech Connect

    Rubbens, I.B.H.M.; Murat, R.C.; Vankeulen, J.

    1983-03-01

    Following the discovery of non-structurally trapped oil accumulations in Cretaceous chalky reservoirs on the northern flank of the North Dome offshore QATAR, a seismic lateral prediction study was carried out for QATAR GENERAL PETROLEUM CORPORATION (Offshore Operations). The objectives of this study were to assist in the appraisal of these oil accumulations by predicting their possible lateral extent and to investigate if the technique applied could be used as a basis for further exploration of similar oil prospects in the area. Wireline logs of eight wells and some 1000 km of high quality seismic data were processed into acoustic impedance (A.I.) logs and seismic A.I. sections. Having obtained a satisfactory match of the A.I. well logs and the A.I. of the seismic traces at the well locations, relationships were established by the use of well log data which allowed the interpretation of the seismic A.I. in terms of reservoir quality. Measurements of the relevant A.I. characteristics were then carried out by computer along all seismic lines and porosity distribution maps prepared for some of the reservoirs. These maps, combined with detailed seismic depth contour maps at reservoir tops, lead to definition of good reservoir development areas downdip from poor reservoir quality zones i.e. of the stratigraphic trap areas, and drilling locations could thus be proposed. The system remains to be adequately calibrated when core material becomes available in the area of study.

  2. NREL/University of Delaware Offshore Wind R&D Collaboration: Cooperative Research and Development Final Report, CRADA Number CRD-10-393

    SciTech Connect

    Musial, Walt

    2015-11-12

    Specifically, the work under this CRADA includes, but is not limited to, the development of test procedures for an offshore test site in Delaware waters; testing of installed offshore wind turbines; performance monitoring of those turbines; and a program of research and development on offshore wind turbine blades, components, coatings, foundations, installation and construction of bottom-fixed structures, environmental impacts, policies, and more generally on means to enhance the reliability, facilitate permitting, and reduce costs for offshore wind turbines. This work will be conducted both at NREL's National Wind Technology Center and participant facilities, as well as the established offshore wind test sites.

  3. Measuring the Stratigraphic Filter in Ancient Deltaic Deposits

    NASA Astrophysics Data System (ADS)

    Trampush, S. M.; Hajek, E. A.

    2014-12-01

    Internal or autogenic sedimentary-system dynamics act as a filter that can dampen or obliterate signals of environmental perturbations, such as changes in climate and tectonics. Additionally, the transfer of material into the sedimentary archive can further degrade environmental signals. Presently we have a poor understanding of the rates, scales, and types of sedimentary processes that influence the stratigraphic filter in natural systems. A set of statistical tools has been developed for estimating the spatial and temporal scales over which the sedimentary filter operates from preserved stratigraphy. These tools, such as the compensation index, have been applied to experimental data and numerical models, with only limited use on outcrop data. Experimental datasets commonly have several orders of magnitude more data than even the most well exposed ancient outcrops; consequently, the ability to confidently use tools in natural systems is limited. Here we present an evaluation of the suitability of the compensation index for measuring and interpreting sedimentary outcrops. In order to constrain uncertainty due to data-set-size limitations, we model the degree to which measurement error, small data sets, and incomplete sampling influence attempts to quantify stratigraphic architecture. We demonstrate the potential for measuring the stratigraphic filter in ancient deposits by evaluating well-exposed deltaic deposits in the Cretaceous Western Interior Seaway that have been interpreted as having different degrees of to wave, tide, and river influence. Ultimately our results underscore how powerful quantitative tools developed in experimental and model datasets must be applied and interpreted with care in ancient deposits where data availability is limited.

  4. Fossil preservation and the stratigraphic ranges of taxa.

    PubMed

    Foote, M; Raup, D M

    1996-01-01

    The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy. Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased.(3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place. PMID:11539203

  5. Fossil preservation and the stratigraphic ranges of taxa

    NASA Technical Reports Server (NTRS)

    Foote, M.; Raup, D. M.

    1996-01-01

    The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy. Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased.(3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place.

  6. Problems unique to offshore measurement

    SciTech Connect

    Young, J.G.

    1995-12-01

    Most of us have arrived at this meeting in some kind of company provided transportation. This is supplied in order for us to do our assigned jobs. These may be trucks, or cars, or even helicopters, and maybe boats. All who are involved in the offshore industry know that transportation is the cost costly of all. The helicopter bill for our company is a bill which costs us somewhere in the 9 million dollar range. Since this costs us so much, we are constantly looking at ways to reduce this. The helicopters we use cost us $510.00 a flying hour plus $28,000.00 a month for lease. These helicopters fly in the neighborhood of 140 miles per hour. You can quickly see how fast the cost can climb. We have two technicians, along with a pilot, and approx. 400 lbs of test gear and spare parts. You have to carry all you think you will need for the day`s activities because it`s a long and costly trip to go pick up some gasket material or an orifice plate.

  7. Laser induced breakdown spectroscopy stratigraphic characterization of multilayered painted surfaces

    NASA Astrophysics Data System (ADS)

    Staicu, A.; Apostol, I.; Pascu, A.; Iordache, I.; Damian, V.; Pascu, M. L.

    2012-08-01

    Laser spectroscopy techniques are modern and competitive methods for elemental analysis. Laser induced breakdown spectroscopy (LIBS), due to its advantages as minimally invasive method that provides real time monitoring and selectivity, is a suitable tool to analyze sample composition. Based on the known emission spectra of heavy metals such as Pb, Zn, Au, Ca, a stratigraphic study regarding the identification of the painting layers content of different mock-up samples was performed. LIBS was used to monitor the laser induced stepwise selective removal of the painting layers and to analyze their composition. The obtained LIBS spectra were correlated with profilometric measurements.

  8. Gulf Coast stratigraphic traps in the Lower Cretaceous carbonates

    SciTech Connect

    Sams, R.H.

    1981-09-01

    Prolific oil and gas production is being obtained from carbonate patch reef reservoirs within Lower Cretaceous formations along the Gulf Coast from Florida to Mexico. Many of these reservoirs are trapped stratigraphically where facies changes within a formation or patch reef unit establish an up-dip permeability barrier. Illustrations of such traps are given from the literature for oil and gas fields in Florida, Mississippi, Louisiana, and E. Texas. A geologic model is presented which provides the explorationist with an actual drilling target suitable to a multiple well exploratory program. 18 references.

  9. Reservoir anatomy within a sequence stratigraphic framework: The Pennsylvanian Breathitt group of Eastern Kentucky

    SciTech Connect

    Aitken, J.F.; Flint, S.S. )

    1993-09-01

    Detailed quantitative sequence stratigraphic analysis and three-dimensional (3-D) modeling of the fluvio-deltaic Pikeville, Hyden, and four Corners formations of the Breathitt Group, eastern Kentucky, indicate that it is possible to make confident deterministic correlations of sand bodies at offshore development well spacings. The key to high-confidence correlation is the delineation of the 3-D architecture of third-order composite sequences, which are seismically mappable, and the recognition of internal fourth-order sequences, which are stacked into lowstand, transgressive, and highstand sequence sets. Volumetric partitioning of reservoir sand bodies between systems tracts and sequences allows prediction of channel sandstone geometries and channel: crevasse splay ratios. Furthermore, channel-fill type is predictable from the sequence stratigraphy. Within 13 studied fourth-order sequences, incised valley fills represent the main reservoirs, which are laterally continuous over tens of kilometers. Sand bodies within transgressive and early highstand systems tracts are usually filled by siltstones or heteroliths and have geometries less than 1.0 km in width. Within fourth-order sequence sets, incised valley fills are sometimes vertically stacked to produce anaomalously thick fluvial sand bodies. These are the prime potential producing zones within coastal plain reservoirs. High-resolution sequence stratigraphy thus provides a deterministic approach to correlation and 3-D modeling. Use of the Stratamodel geocellular modeling system permits circulation of connectivities for different systems tracts and sequence sets, thus allowing the development of conceptual models for perforation policy in complex [open quotes]jigsaw-type[close quotes] reservoirs.

  10. Variations of the sequence stratigraphic model: Past concepts, present understandings, and future directions

    SciTech Connect

    Posamentier, H.W. ); James, D.H. )

    1991-03-01

    The working hypothesis upon which the sequence concepts are based is that the relative sea level change results in changes in the capacity of a basin to accommodate sediment, which, in turn, results in a succession of sequences. The interplay between eustasy, tectonics, sediment flux, and physiography yields a predictable geologic response in carbonate, clastic, as well as mixed carbonate/clastic settings. The criteria for recognition of sequence boundaries can be varied within a given basin as well as between basins. They include but are not restricted to (1) a basinward shift of facies across a sharp bedding contact, (2) onlapping stratal geometry, and (3) truncation of strata. The key to the correct utilization of these concepts is to recognize sequence stratigraphy as an approach or a tool rather than a rigid template. Observations from the upper Albian, Cretaceous, Viking Formation of the western Canadian sedimentary basin are presented to illustrate the stratigraphic expression of clastic depositional sequences on a ramp margin. In this setting, forced regressions and lowstand shorelines commonly occur, incised valleys sometimes occur, and submarine fans rarely occur, in response to fluctuations of relative sea level. The base of the Viking Formation sometimes is characterized by relatively coarse-grained sediments sharply overlying fine-grained offshore muds and is interpreted as a third-order sequence boundary. Pebbles occasionally are observed at this contact. Subsequently, a number of higher-order sequences within the lower to middle Viking are observed and are characterized by the occurrence of forced regressions and lowstand shorelines without associated incised valleys.

  11. Offshore well support miniplatform

    SciTech Connect

    Blandford, J.W.

    1987-07-14

    This patent describes a protective well support system installed on an offshore well having an upstanding conductor pipe extending above the seabed, the system comprising: (a) an upstanding conductor clamp (adapts to encircle the conductor pipe) formed by two upstanding facing members supported by a bottom engaging frame; (b) the frame including frame members joined together defining a substantially horizontal rectangular support frame for engaging the seabed; (c) angularly extending brace members secured at one end to the conductor clamp and at the other end to the frame; (d) the conductor clamp attaches to the frame and extending upright to enable the conductor clamp to fasten about the conductor pipe; (e) a boat landing mounts about the conductor pipe, the boat landing formed by at least two sectional components fixedly secured to semicircular clamp members adapted to encircle the conductor pipe for mounting the boat landing components; and (f) well platform means supported on bracket means adapted to encircle the conductor pipe for removably securing the well platform means.

  12. Reassessment of offshore platforms

    SciTech Connect

    Nair, V.V.D.; Kuhn, J.M. )

    1993-05-01

    Data from Hurricane Andrew demonstrated that the systems and procedures in place for evacuating offshore workers and minimizing oil spills and environmental damage functioned as planned. While the vast majority of the platforms survived the storm with no damage, a few of the older platforms (installed prior to 1972) either collapsed or suffered severe damage. The collapsed platforms were designed with insufficient deck height to clear the storm waves. In recent years, the API RP 2A has introduced guidance for minimum air gap, minimum structures, platform inspection and platform reuse. These provisions, coupled with natural attribution of the older platforms, will significantly improve the performance of platforms in the future. The reliability of NDT techniques to detect major structural defects should be improved through continued research. While flooded member detection is used by several operators as a screening tool to detect major defects underwater, its reliability is not always good and further research is needed in this area. Another area of high priority research is related to the use of Remotely Operated Vehicles (ROV) to perform underwater inspection of structures. 51 refs., 7 figs.

  13. Ichnofabric and siliciclastic depositional systems: Integration for sequence stratigraphic analysis

    SciTech Connect

    Bottjer, D.J. ); Droser, M.L. )

    1991-03-01

    Much previous research on biogenic sedimentary structures has established how ichnofacies (assemblages of discrete trace fossils) vary within marine depositional systems. However, studies aimed at understanding the distribution of ichnofabric (sedimentary rock fabric resulting from biogenic reworking) have only recently been attempted. Because ichnofabric can be recorded using a semi-quantitative series of ichnofabric indices (ii), its distribution in marine sedimentary rocks can be easily recorded through vertical sequence analysis. Thicknesses of strata recording different ichnofabric indices can be logged from stratigraphic sections or cores. These data are best displayed in histograms as percent of ii recorded from the total thickness measured. These ichnofabric histograms (ichnograms) show variable but distinctive distributions for genetic units such as facies within systems tracts of siliciclastic depositional sequences. An average ichnofabric index for any genetic sedimentary unit can also be computed from the data used to construct ichnograms. Because skeletal fossils are typically much less commonly preserved in siliciclastic than carbonate depositional systems, such ichnofabric analyses have the potential of providing an important new line of evidence for depositional systems and sequence stratigraphic analysis of siliciclastic strata. In petroleum exploration results from completing analyses of ichnofabric distribution could provide important information including: (1) systems tracts with fine-grained facies that have relatively low ichnofabric values are potential source beds; and (2) petroleum reservoirs that occur in coarse episodically deposited beds are more likely to from in systems tracts with facies that have low rather than high ichnofabric values.

  14. Harmony field, Clarke County, Mississippi: a true stratigraphic trap

    SciTech Connect

    Lieber, R.B.; Carothers, M.C.

    1983-09-01

    Harmony field in Clarke County, Mississippi, has produced approximately 2 million bbl of oil since its discovery in 1968. Production has been from oolitic grainstones in the upper Jurasic Smackover Formation. The trappng mechanism at Harmony field is a complex stratigraphic trap. Porous oolitic grainstones pinch out updip into tight carbonates and anhydrite. Structure contour maps on top of the Smackover Formation indicate a low relief structural nose associated with the field. Additional structure maps contoured at the top of the Haynesville anhydrite, approximately 500 ft (150 m) above the top of the Smackover, reveal only regional southwesterly dip. An isopach map of the interval between the two structural markers shows a thinning of Haynesville section coincident with the field area. Evidence suggests, therefore, that the porous Smackover in Harmony field was deposited with depositional relief above the surrounding sediments. This relief had been completely masked by the time the Haynesville anhydrite was deposited. Stratigraphic and structural cross sections using the Haynesville anhydrite as datum indicate the Smackover in Harmony field consists of not one, but multiple, thin olitic zones which are productive in various portions of the field. These zones grade laterally as well as updip into nonporous anhydritic carbonates. The Smackover Formation is often considered to be a chronolithologic unit. In the Harmony field area it is a lithostratigraphic unit, i.e. a unit defined not by time but by a particular rock type, in this case a porous limestone.

  15. Offshore Wind Energy Market Overview (Presentation)

    SciTech Connect

    Baring-Gould, I.

    2013-07-01

    This presentation describes the current international market conditions regarding offshore wind, including the breakdown of installation costs, how to reduce costs, and the physical siting considerations considered when planning offshore wind construction. The presentation offers several examples of international existing and planned offshore wind farm sites and compares existing international offshore resources with U.S. resources. The presentation covers future offshore wind trends and cites some challenges that the United States must overcome before it will be able to fully develop offshore wind sites.

  16. Venusian extended ejecta deposits as time-stratigraphic markers

    NASA Technical Reports Server (NTRS)

    Izenberg, Noam R.

    1992-01-01

    Use of impact crater ejects at time-stratigraphic markers was established during lunar geologic mapping efforts. The basic premise is that the deposition of impact ejecta, either by itself or mixed with impact-excavated material, is superimposed on a surface. The deposit becomes an observable, mappable unit produced in a single instant in geologic time. Up to two-thirds of Venus craters exhibit extended ejecta deposits. A reconnaissance survey of 336 craters (about 40 percent of the total population) was conducted. About half the craters examined were located in and around the Beta-Atla-Themis region, and half were spread over the western hemisphere of the planet. The survey was conducted using primarily C1-MIDR images. The preliminary survey shows: (1) of the 336 craters, 223 were found to have extended ejecta deposits. This proportion is higher than that found in other Venus crater databases by up to a factor of 2. (2) 53 percent of all extended ejecta craters were unambiguously superimposed on all volcanic and tectonic units. Crater Annia Faustina's associated parabolic ejecta deposit is clearly superimposed on volcanic flows coming from Gula Mons to the west. Parabola material from Faustina has covered the lava flows, smoothing the surface and reducing its specific backscatter cross section. The stratigraphy implies that the parabola material is the youngest observable unit in the region. (3) 12 percent of extended ejecta deposits are superimposed by volcanic materials. Crater Hwangcini has extended ejecta that has been covered by volcanic flows from a dome field to the northwest, implying that the volcanic units were emplaced subsequent to the ejecta deposit and are the youngest units in the locality. (4) It is difficult to determine the stratigraphic relationships of the remaining extended ejecta deposits in SAR at C1-MIDR resolution. Examination of higher resolution images and application of the other Magellan datasets in systematic manner should resolve most of the ambiguous cases. Results from the preliminary survey indicate that extended ejecta deposits are effective time-statigraphic markers for the localities. If stratigraphic relationships between the deposits and surrounding units are studied on a case-by-case basis over the whole planet, they should provide useful constraints on Venus history and development of the surface through time. The continuation of the research will expand the study to include the entire crater population and the Magellan emissivity, altimetry, reflectivity, and rms slope datasets.

  17. OWL representation of the geologic timescale implementing stratigraphic best practice

    NASA Astrophysics Data System (ADS)

    Cox, S. J.

    2011-12-01

    The geologic timescale is a cornerstone of the earth sciences. Versions are available from many sources, with the following being of particular interest: (i) The official International Stratigraphic Chart (ISC) is maintained by the International Commission for Stratigraphy (ICS), following principles developed over the last 40 years. ICS provides the data underlying the chart as part of a specialized software package, and the chart itself as a PDF using the standard colours; (ii) ITC Enschede has developed a representation of the timescale as a thesaurus in SKOS, used in a Web Map Service delivery system; (iii) JPL's SWEET ontology includes a geologic timescale. This takes full advantage of the capabilities of OWL. However, each of these has limitations - The ISC falls down because of incompatibility with web technologies; - While SKOS supports multilingual labelling, SKOS does not adequately support timescale semantics, in particular since it does not include ordering relationships; - The SWEET version (as of version 2) is not fully aligned to the model used by ICS, in particular not recognizing the role of the Global Boundary Stratotype Sections and Point (GSSP). Furthermore, it is distributed as static documents, rather than through a dynamic API using SPARQL. The representation presented in this paper overcomes all of these limitations as follows: - the timescale model is formulated as an OWL ontology - the ontology is directly derived from the UML representation of the ICS best practice proposed by Cox & Richard [2005], and subsequently included as the Geologic Timescale package in GeoSciML (http://www.geosciml.org); this includes links to GSSPs as per the ICS process - key properties in the ontology are also asserted to be subProperties of SKOS properties (topConcept and broader/narrower relations) in order to support SKOS-based queries; SKOS labelling is used to support multi-lingual naming and synonyms - the International Stratigraphic Chart is implemented as a set of instances of classes from the ontology, and published through a SPARQL end-point - the elements of the Stratigraphic chart are linked to the corresponding elements in SWEET (Raskin et al., 2011) and DBpedia to support traceability between different commonly accessed representations. The ontology builds on standard geospatial information models, including the Observations and Measurements model (ISO 19156), and GeoSciML. This allows the ages given in the chart to be linked to the evidence basis found in the associated GeoSciML features.

  18. Potential threats to offshore platforms

    SciTech Connect

    Jenkins, B.M.

    1988-01-01

    Increasingly spectacular acts of terrorism have led to growing concern that terrorists will move beyond the symbols of society and directly attack its technological and industrial vulnerabilities. Offshore platforms have been frequently mentioned among the potential targets terrorists might attack. This concern, however, has not resulted in extensive research like that devoted to possible threats to nuclear facilities, which have also been frequently mentioned as possible future targets of terrorists. For one thing, offshore drilling does not invoke the fear inherent in the word nuclear, a fear that translates directly into heavy security for the nuclear industry. Neither does the construction of offshore platforms provoke anything like the kind of protest generated by the construction of nuclear facilities.

  19. Offshore Energy Knowledge Exchange Workshop Report

    SciTech Connect

    none,

    2012-04-12

    A report detailing the presentations and topics discussed at the Offshore Energy Knowledge Exchange Workshop, an event designed to bring together offshore energy industry representatives to share information, best practices, and lessons learned.

  20. Offshore wind farm layout optimization

    NASA Astrophysics Data System (ADS)

    Elkinton, Christopher Neil

    Offshore wind energy technology is maturing in Europe and is poised to make a significant contribution to the U.S. energy production portfolio. Building on the knowledge the wind industry has gained to date, this dissertation investigates the influences of different site conditions on offshore wind farm micrositing---the layout of individual turbines within the boundaries of a wind farm. For offshore wind farms, these conditions include, among others, the wind and wave climates, water depths, and soil conditions at the site. An analysis tool has been developed that is capable of estimating the cost of energy (COE) from offshore wind farms. For this analysis, the COE has been divided into several modeled components: major costs (e.g. turbines, electrical interconnection, maintenance, etc.), energy production, and energy losses. By treating these component models as functions of site-dependent parameters, the analysis tool can investigate the influence of these parameters on the COE. Some parameters result in simultaneous increases of both energy and cost. In these cases, the analysis tool was used to determine the value of the parameter that yielded the lowest COE and, thus, the best balance of cost and energy. The models have been validated and generally compare favorably with existing offshore wind farm data. The analysis technique was then paired with optimization algorithms to form a tool with which to design offshore wind farm layouts for which the COE was minimized. Greedy heuristic and genetic optimization algorithms have been tuned and implemented. The use of these two algorithms in series has been shown to produce the best, most consistent solutions. The influences of site conditions on the COE have been studied further by applying the analysis and optimization tools to the initial design of a small offshore wind farm near the town of Hull, Massachusetts. The results of an initial full-site analysis and optimization were used to constrain the boundaries of the farm. A more thorough optimization highlighted the features of the area that would result in a minimized COE. The results showed reasonable layout designs and COE estimates that are consistent with existing offshore wind farms.

  1. Drilling rate for the Cerro Prieto stratigraphic sequence

    SciTech Connect

    Prian C, R.

    1981-01-01

    Drilling practice at the field has been modified in several ways as better information is being obtained. The stratigraphic sequence of the area is made up of three sedimentary rock units of deltaic origin having different densities. These units have been named non-consolidated, semi-consolidated, and consolidated rocks; the thermal reservoirs are located in the latter. To investigate how the drilling rates are affected by the three rock units, plots of drilling advance versus time were made for a large number of wells. A typical plot is shown and drilling rates are practically constant in three different zones; that is, the drilling rate has only two breaks or changes in slope.

  2. 3-D seismic has renewed the search for stratigraphic traps

    SciTech Connect

    Garvey, C.F. ); Gibson, W.R.

    1992-09-01

    Exploration activity has been stimulated in two Lower Permian oil plays of the West Texas Permian basin by a string of economically successful well completions beginning in early 1991. This paper reports that stratigraphic oil targets in each of these trends were identified by new geologic analysis and three dimensional (3-D) seismic methods. The locations of these discoveries are shown. The two Wolfcamp carbonate detrital formations are characterized by clusters of rich oil accumulations in discontinuous reservoir pods that are relatively small in aerial extent. These objectives are generally encountered at drilling depths of about 8,000 to 9,000 ft. 3-D seismic proved to be a cost effective exploration and exploitation technique in these plays.

  3. Stratigraphical distribution of the Ordovician conodont Erraticodon Dzik in Argentina

    NASA Astrophysics Data System (ADS)

    Heredia, S.; Carlorosi, J.; Mestre, A.; Soria, T.

    2013-08-01

    Three different species of the Ordovician genus Erraticodon Dzik are described and illustrated. Erraticodon patu Cooper is reported from the Lower-Midde Ordovician strata of the Acoite and Alto del Cndor formations. E. cf. Erraticodon balticus and Erraticodon hexianensis from Middle Ordovician carbonate deposits of the San Juan Formation are analyzed and compared to specimens of these species from Australia, China, Newfoundland, and Baltica. E. patu and E. hexianensis are recorded for first time in the San Juan Formation of Precordillera. The elements of E. cf. E. balticus resemble closely E. balticus Dzik but lack the important denticle on the posterior process of the S elements. An evaluation of the stratigraphic occurrences of these species relative to those of key Lower and Middle Ordovician conodont species such as Trapezognathus diprion Lindstrm, Oepikodus intermedius Serpagli, Baltoniodus triangularis (Lindstrm), Baltoniodus navis Lindstrm, Yangtzeplacognathus crassus (Chen and Zhang) and Eoplacognathus pseudoplanus (Viira) indicates they value for biostratigraphic correlation.

  4. Stratigraphic interpretation of seismic data on the workstation

    SciTech Connect

    Bahorich, M.; Van Bemmel, P.

    1994-12-31

    Until recently, interpretation of seismic data in the workstation environment has been restricted primarily to horizon and attribute maps. Interpreters have not had the ability to make various types of notations on seismic data and subsequent map views as has been done for years on paper. New thinking in the industry is leading to the development of software which provides the geoscientist with a broader range of interpretive functionality on seismic and subsequent map views. This new functionality reduces the tedious bookkeeping tasks associated with seismic sequence stratigraphy and facies analysis. Interpreters may now perform stratigraphic analysis in more detail in less time by employing the power of the interpretive workstation. A data set over a deep-water fan illustrates the power of this technology.

  5. Production using steam injection moves offshore in California field

    SciTech Connect

    Rintoul, B.

    1981-10-01

    Aminoil USA Inc. is initiating what is believed to be the oil industry's first effort to stimulate oil production with steam injection from a domestic offshore platform in California. It is part of a campaign to revitalize the Huntington Beach field, a 1920 discovery 35 miles southeast of downtown Los Angeles. Aminoil's present production from the field is approximately 20,800 bpd, including approximately 19,000 bpd from the offshore portion of the field. The company hopes to boost daily production to 28,000 bpd by 1988. Aminoil and predecessor companies have been operating the Huntington Beach field since the late 1930s, producing nearly 500 million bbl of oil over that period. An equivalent amount may still remain in the ground. Aminoil is undertaking the test program, including offshore steam injection, to determine how much of that volume may be economically and technically recovered.

  6. Seismic attenuation of the inner core: Viscoelastic or stratigraphic?

    USGS Publications Warehouse

    Cormier, V.F.; Xu, L.; Choy, G.L.

    1998-01-01

    Broadband velocity waveforms of PKIKP in the distance range 150??to 180??are inverted for inner core attenuation. A mean Q?? of 244 is determined at 1 Hz from 8 polar and 9 equatorial paths. The scatter in measured Q-1 exceeds individual error estimates, suggesting significant variation in attenuation with path. These results are interpreted by (1) viscoelasticity, in which the relaxation spectrum has a low-frequency corner near or slightly above the frequency band of short-period body waves, and by (2) stratigraphic (scattering) attenuation, in which attenuation and pulse broadening are caused by the interference of scattered multiples in a velocity structure having rapid fluctuations along a PKIKP path. In the scattering interpretation, PKIKP attenuation is only weakly affected by the intrinsic shear attenuation measured in the free-oscillation band. Instead, its frequency dependence, path variations, and fluctuations are all explained by scattering attenuation in a heterogeneous fabric resulting from solidification texturing of intrinsically anisotropic iron. The requisite fabric may consist of either single or ordered groups of crystals with P velocity differences of at least 5% and as much as 12% between two crystallographic axes at scale lengths of 0.5 to 2 km in the direction parallel to the axis of rotation and longer in the cylindrically radial direction, perpendicular to the axis of rotation.Broadband velocity waveforms of PKIKP in the distance range 150?? to 180?? are inverted for inner core attenuation. A mean Q?? of 244 is determined at 1 Hz from 8 polar and 9 equatorial paths. The scatter in the measured Q-1 exceeds individual error estimates, indicating significant variation in attenuation with path. The results are interpreted by viscoelasticity and stratigraphic (scattering) attenuation.

  7. Forward stratigraphic modeling of the Permian of the Delaware Basin

    SciTech Connect

    Qiucheng, Ye; Kerans, C.; Bowman, S. )

    1996-01-01

    Permian platform-to-basin strata of the Delaware Basin In west Texas and New Mexico represent one of the world's most complete, best studied, and most hydrocarbon productive records of this geologic period in the world. This superb marriage of a refined stratigraphic framework and active exploration provided impetus to develop a forward stratigraphic model of this section to better predict the distribution of reservoir and seal relationships. The approximately 30 m.y. interval modeled is composed of 2 km of platform strata and 3 km of basinal strata divided into 8 composite sequences (average 3 m.y. duration) and 45 high-frequency sequences (400 ky m.y. duration). A 130 km dip section through the basin margin Guadalupe/Deleware Mountain outcrop is inversely modeled to derive local tectonic subsidence and a sea level curve for the Permian. In this process, the highest and lowest shoreline positions of each sequence are interpreted based on facies description which are assumed to approximate the highest and lowest relative sea level. A eustatic sea level curve is calculated by restoring these shoreline positions and removing local tectonic subsidence using a polynomial fit to the derived relative sea level curve. The quantitatively constrained curve for the Permian contains 2nd, 3rd, and 4th order 180m. This quantitatively constrained accommodation history (calculated eustatic curve and subsidence history) are input into the PHIL forward modeling program. Model variables of sediment supply are depositional system are adjusted to match known outcrop relations. The resulting model is potentially capable of predicting stratigraphy elsewhere in the basin using only subsidence history data from the inverse model.

  8. Forward stratigraphic modeling of the Permian of the Delaware Basin

    SciTech Connect

    Qiucheng, Ye; Kerans, C.; Bowman, S.

    1996-12-31

    Permian platform-to-basin strata of the Delaware Basin In west Texas and New Mexico represent one of the world`s most complete, best studied, and most hydrocarbon productive records of this geologic period in the world. This superb marriage of a refined stratigraphic framework and active exploration provided impetus to develop a forward stratigraphic model of this section to better predict the distribution of reservoir and seal relationships. The approximately 30 m.y. interval modeled is composed of 2 km of platform strata and 3 km of basinal strata divided into 8 composite sequences (average 3 m.y. duration) and 45 high-frequency sequences (400 ky m.y. duration). A 130 km dip section through the basin margin Guadalupe/Deleware Mountain outcrop is inversely modeled to derive local tectonic subsidence and a sea level curve for the Permian. In this process, the highest and lowest shoreline positions of each sequence are interpreted based on facies description which are assumed to approximate the highest and lowest relative sea level. A eustatic sea level curve is calculated by restoring these shoreline positions and removing local tectonic subsidence using a polynomial fit to the derived relative sea level curve. The quantitatively constrained curve for the Permian contains 2nd, 3rd, and 4th order 180m. This quantitatively constrained accommodation history (calculated eustatic curve and subsidence history) are input into the PHIL forward modeling program. Model variables of sediment supply are depositional system are adjusted to match known outcrop relations. The resulting model is potentially capable of predicting stratigraphy elsewhere in the basin using only subsidence history data from the inverse model.

  9. Chemical Contaminants as Stratigraphic Markers for the Anthropocene

    NASA Astrophysics Data System (ADS)

    Kruge, M. A.

    2012-12-01

    Thousands and even millions of years from now, widespread anthropogenic contaminants in sediments would likely persist, incorporated into the geological record. They would inadvertently preserve evidence of our present era (informally designated as the Anthropocene Epoch) characterized by large human populations engaged in intensive industrial and agricultural activities. Hypothetical geologists in the distant future would likely find unusually high concentrations of a wide variety of contaminants at stratigraphic levels corresponding to our present time, analogous to the iridium anomaly marking the bolide impact event at the close of the Cretaceous Period. These would include both organic and inorganic substances, such as industrially-derived heavy metals (e.g., Hg, Pb, Cr, Zn) and hydrocarbons, both petrogenic (derived directly from petroleum) and pyrogenic (combustion products). While there are natural sources for these materials, such as volcanic eruptions, wildfires, and oil seeps, their co-occurrence would provide a signature characteristic of human activity. Diagnostic assemblages of organic compounds would carry an anthropogenic imprint. The distribution of polycyclic aromatic hydrocarbons (PAHs) in a sediment sample could distinguish between natural and human sources. Stable isotopic signatures would provide additional evidence. Concentrations of contaminants in the sedimentary record would increase exponentially with increasing proximity to urban source areas, where at present billions of people are collectively consuming vast quantities of fossil fuels and generating large amounts of waste. Aolian and marine transport prior to deposition has been seen at present to globally redistribute detectable amounts of contaminants including Hg and PAHs, even at great distances from principal source areas. For organic contaminants, deposition in an anoxic sedimentary environment could insure their preservation, increasing the likelihood of their inclusion in the long-term stratigraphic record, establishing markers of the Anthropocene Epoch for millions of years to come.

  10. Cenozoic stratigraphic evolution, North Sea and Labrador Sea

    SciTech Connect

    Gradstein, F.M.; Grant, A.C.; Mudford, B.S. ); Berggren, W.A. ); Kaminski, M.A. ); D'Lorio, M.A. ); Cloetingh, S. ); Griffiths, C.M. )

    1990-05-01

    The authors are studying Cenozoic correlation patterns, burial trends, and subsidence history of the Central North Sea, Labrador, and Orphan basins. The authors objectives are (1) to detail intraregional mid-high latitude biozonations using noise filtering and probabilistic zonation techniques; (2) to detail paleobathymetric trends from basin margins to centers; (3) to apply this knowledge to model basin evolution, in the perspective of the evolving North Atlantic Ocean; (4) to evaluate causes for the occurrence of major hiatuses and rapid changes of subsidence; and (5) to relate rapid changes in sedimentation in the last few millions of years to model observed undercompaction trends. Cenozoic microfossil assemblages in these basins are similar, related to similarities in sedimentary and paleoeceanographic conditions. In more basinal wells, flysch-type agglutinated foraminiferal assemblages occur, also known from Carpathians, Trinidad, and Moroccan foredeeps. Over 90% of agglutinated taxa are common between these basins, although local stratigraphic ranges vary sufficiently to rely on the concept of average ranges, rather than total ones for correlations. Cenozoic stratigraphic resolution in the North Sea and Labrador basins generally is in 3-5-Ma units. and paleobathymetric zonations define a minimum of five niches, from inner shelf to middle slope regimes. Significant hiatuses occurred in the late Eocene through the Miocene, particularly in northern Labrador and northern North Sea. Subsidence in the Labrador/Grand Banks passive margin half grabens was strongly influenced by Labrador Sea opening between anomalies 34 (Campanian) and 13 (early Oligocene), when subsidence exceeded sedimentation and bathyal conditions prevailed along the margin. Thermally induced subsidence in the central North Sea grabens was considerable in the late Paleocene, when the Norwegian Sea started to open.

  11. Geologic evolution and sequence stratigraphy of the offshore Pelotas Basin, southeast Brazil

    SciTech Connect

    Abreu, V.S.

    1996-12-31

    The Brazilian marginal basins have been studied since the beginning of the 70s. At least nine large basins are distributed along the entire Eastern continental margin. The sedimentary infill of these basins consists of lower Cretaceous (continental/lacustrine) rift section underlying marine upper Cretaceous (carbonate platforms) and marine upper Cretaceous/Tertiary sections, corresponding to the drift phase. The sedimentary deposits are a direct result of the Jurassic to lower Cretaceous break-up of the Pangea. This study will focus on the geologic evolution and sequence stratigraphic analysis of the Pelotas basin (offshore), located in the Southeast portion of the Brazilian continental margin between 28{degrees} and 34{degrees} S, covering approximately 50,000 Km{sup 2}. During the early Cretaceous, when the break-up of the continent began in the south, thick basaltic layers were deposited in the Pelotas basin. These basalts form a thick and broad wedge of dipping seaward reflections interpreted as a transitional crust. During Albian to Turonian times, due to thermal subsidence, an extensive clastic/carbonate platform was developed, in an early drift stage. The sedimentation from the upper Cretaceous to Tertiary was characterized by a predominance of siliciclastics in the southeast margin, marking an accentuate deepening of the basin, showing several cycles related to eustatic fluctuations. Studies have addressed the problems of hydrocarbon exploration in deep water setting within a sequence stratigraphic framework. Thus Pelotas basin can provide a useful analogue for exploration efforts worldwide in offshore passive margins.

  12. Geologic evolution and sequence stratigraphy of the offshore Pelotas Basin, southeast Brazil

    SciTech Connect

    Abreu, V.S. )

    1996-01-01

    The Brazilian marginal basins have been studied since the beginning of the 70s. At least nine large basins are distributed along the entire Eastern continental margin. The sedimentary infill of these basins consists of lower Cretaceous (continental/lacustrine) rift section underlying marine upper Cretaceous (carbonate platforms) and marine upper Cretaceous/Tertiary sections, corresponding to the drift phase. The sedimentary deposits are a direct result of the Jurassic to lower Cretaceous break-up of the Pangea. This study will focus on the geologic evolution and sequence stratigraphic analysis of the Pelotas basin (offshore), located in the Southeast portion of the Brazilian continental margin between 28[degrees] and 34[degrees] S, covering approximately 50,000 Km[sup 2]. During the early Cretaceous, when the break-up of the continent began in the south, thick basaltic layers were deposited in the Pelotas basin. These basalts form a thick and broad wedge of dipping seaward reflections interpreted as a transitional crust. During Albian to Turonian times, due to thermal subsidence, an extensive clastic/carbonate platform was developed, in an early drift stage. The sedimentation from the upper Cretaceous to Tertiary was characterized by a predominance of siliciclastics in the southeast margin, marking an accentuate deepening of the basin, showing several cycles related to eustatic fluctuations. Studies have addressed the problems of hydrocarbon exploration in deep water setting within a sequence stratigraphic framework. Thus Pelotas basin can provide a useful analogue for exploration efforts worldwide in offshore passive margins.

  13. Comparison of Offshore Turbidite records and Lake Disturbance Events at the Latitude of Seattle, Washington

    NASA Astrophysics Data System (ADS)

    Galer, S.; Goldfinger, C.; Morey, A. E.; Black, B.; Romsos, C.; Beeson, J. W.; Erhardt, M.

    2014-12-01

    We are investigating the paleoseismic history of northern Washington using offshore turbidite cores and lake sediments collected from forearc lakes along a transect from offshore to Seattle, Washington. Additional offshore cores, ash determinations and heavy mineral analysis flesh out the turbidite stratigraphy off northern Washington, and support 3-5 proximal turbidites in northern Washington canyons (see Adams, 1990) in addition to the 19 regionally correlated beds. Onshore, we have cored multiple lakes including (west to east) Beaver, Leland, Tarboo, Hall, Sawyer, and Wapato, east of the Cascades, and collected multibeam bathymetry, backscatter and chirp subbottom data. These lakes are small (2-113 ha), 6-18 m deep, and are all kettle lakes except Beaver Lake (landslide-dammed) and Wapato Lake, a glacial scour. These lakes were selected for their limited outside sediment sources and low sensitivity to ground shaking. The sedimentology is mostly organic-rich gyttja. All lakes contain the Mazama ash based on its similar depth occurrence in previously published cores and new EMP analysis. Computed Tomography (CT) density, gamma density, and magnetic susceptibility (ms) data show there is more stratigraphic variability than is visually apparent. Low-energy disturbance events are apparent in the stratigraphy of all lakes (except Hall) as increases in clastics, density, and ms. The number of post Mazama disturbance events is similar to the number of expected great earthquakes found offshore and onshore, though definition of the boundaries of the lake events is much less clear. Initial radiocarbon results and preliminary correlations along this 185 km transect show strong similarities in stratigraphic records between these cores over the past ~7600 years, anchored by the Mazama tephra. Preliminary comparisons with offshore cores show a striking similarity in downcore variability in physical properties. Given the evidence for earthquake origin for the offshore cores, and the strong common signal across the lake transect, we suggest that the lake disturbance events are likely of earthquake origin, representing turbidites generated internally within each lake. Analysis continues with the goal of estimating slope stability and minimum levels of ground shaking required to destabilize lake margins.

  14. P-wave velocity features of methane hydrate-bearing turbidity sediments sampled by a pressure core tool, from the first offshore production test site in the eastern Nankai Trough, Japan

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Santamarina, C. J.; Waite, W. F.; Winters, W. J.; Ito, T.; Nakatsuka, Y.; Konno, Y.; Yoneda, J.; Kida, M.; Jin, Y.; Egawa, K.; Fujii, T.; Nagao, J.

    2013-12-01

    Turbidite sediments around the production test site at Daini-Atsumi knoll were deposited under channel and lobe environments of a submarine fan. Changes in physical properties of the sediments are likely caused by differences in the depositional environments. In addition, methane hydrate (MH) crystals growing among sediment grains alter the sediment's original physical properties. Thus, distinguishing between hydrate-bearing sediment and hydrate-free sediment based only on physical property changes measured during downhole logging can be difficult. To more precisely analyze sediment properties, core samples of MH-bearing sediments were taken at the first offshore MH production test site. Samples were collected using a wireline hybrid pressure coring system (Hybrid PCS), which retains downhole pressure, thereby preventing dissociation of MH in the sampled cores. Nondestructive, high-pressure analyses were conducted in both the 2012 summer drilling campaign and a 2013 winter laboratory study in Sapporo. To handle Hybrid PCS cores during the pressure coring campaign in the summer of 2012, a pressure core analysis and transfer system (PCATS) was installed on the research vessel Chikyu (Yamamoto et al., 2012). PCATS P-wave velocity measurements were made at in situ water pressure without causing any core destruction or MH dissociation. In January 2013, Georgia Tech (GT), USGS, AIST, and JOGMEC researchers used pressure core characterization tools (PCCTs) developed by GT to re-measure the P-wave velocity of the MH-bearing sediments at high pressure and low, non-freezing temperature. In the PCATS analysis, results showed a difference of more than 1,200 m/s in P-wave velocities between the MH-bearing sandy and muddy layers. This difference in P-wave velocities was confirmed by PCCTs measurements. P-wave velocities within the turbidite interval tend to decrease upward with the textural grading of the turbidite. Our result implies that MH concentration, which is related to the pore size of sediments, tends to be highest in coarser layers, enhancing the P-wave velocity change through the turbidite. Acknowledgement Authors would like to express thanks to Geotek for their assistance during the 2012 pressure core operation/analysis. This research is conducted as a part of MH21 research and the authors would like to express their sincere appreciation to MH21 and the Ministry of Economy, Trade and Industry for disclosure permission for this research.

  15. A MATLAB®-based program for 3D visualization of stratigraphic setting and subsidence evolution of sedimentary basins: example application to the Vienna Basin

    NASA Astrophysics Data System (ADS)

    Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

    2015-04-01

    In recent years, 3D visualization of sedimentary basins has become increasingly popular. Stratigraphic and structural mapping is highly important to understand the internal setting of sedimentary basins. And subsequent subsidence analysis provides significant insights for basin evolution. This study focused on developing a simple and user-friendly program which allows geologists to analyze and model sedimentary basin data. The developed program is aimed at stratigraphic and subsidence modelling of sedimentary basins from wells or stratigraphic profile data. This program is mainly based on two numerical methods; surface interpolation and subsidence analysis. For surface visualization four different interpolation techniques (Linear, Natural, Cubic Spline, and Thin-Plate Spline) are provided in this program. The subsidence analysis consists of decompaction and backstripping techniques. The numerical methods are computed in MATLAB® which is a multi-paradigm numerical computing environment used extensively in academic, research, and industrial fields. This program consists of five main processing steps; 1) setup (study area and stratigraphic units), 2) loading of well data, 3) stratigraphic modelling (depth distribution and isopach plots), 4) subsidence parameter input, and 5) subsidence modelling (subsided depth and subsidence rate plots). The graphical user interface intuitively guides users through all process stages and provides tools to analyse and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the visualization results using the full range of available plot options in MATLAB. All functions of this program are illustrated with a case study of Miocene sediments in the Vienna Basin. The basin is an ideal place to test this program, because sufficient data is available to analyse and model stratigraphic setting and subsidence evolution of the basin. The study area covers approximately 1200 km2 including 110 data points in the central part of the Vienna Basin.

  16. Application of sequence stratigraphy to oil and gas exploration in Bredasdorp basin offshore South Africa

    SciTech Connect

    Van Wyk, N.J.S.

    1989-03-01

    For more than two decades, oil and gas exploration in offshore South African rift basins within structural synrift plays yielded limited success. After the first oil discovery in postrift sediments in the Bredasdorp basin in 1987, sequence-stratigraphic concepts were applied to the Lower Cretaceous postrift sequences to permit correlation of depositional systems tracts and related facies throughout the basin. Extensive high-resolution seismic coverage and borehole control supported the study. The interplay of diminishing rift tectonics, thermal cooling, and inferred eustatic variations in global sea level produced a distinctive series of repetitive cycle depositional sequences. As many as 10 cyclic sequences and megasequences, deposited between the mid-Valanginian and lower Santonian, can be recognized within resolution limits of regional seismic profiles. Various elements of lowstand systems tracts within these sequences appear to contain potential reservoirs. Highly erosional (type 1) unconformities, commonly exhibiting incised valleys and canyons, provide surfaces on which (1) mounded and sheetlike submarine/basin-floor fans, (2) submarine channel fill and associated mounds and fans, and (3) prograding deltaic/coastal lowstand wedges were deposited. These fans, channel fills, and wedges are top sealed and sourced by transgressive shales and marine condensed sections, deposited at a time of regional transgression of the shoreline. One discovery well and various reservoir-quality sandstones occurring at predicted stratigraphic levels in other wells support the application of the sequence-stratigraphic concepts to hydrocarbon exploration.

  17. Foundations for offshore wind turbines.

    PubMed

    Byrne, B W; Houlsby, G T

    2003-12-15

    An important engineering challenge of today, and a vital one for the future, is to develop and harvest alternative sources of energy. This is a firm priority in the UK, with the government setting a target of 10% of electricity from renewable sources by 2010. A component central to this commitment will be to harvest electrical power from the vast energy reserves offshore, through wind turbines or current or wave power generators. The most mature of these technologies is that of wind, as much technology transfer can be gained from onshore experience. Onshore wind farms, although supplying 'green energy', tend to provoke some objections on aesthetic grounds. These objections can be countered by locating the turbines offshore, where it will also be possible to install larger capacity turbines, thus maximizing the potential of each wind farm location. This paper explores some civil-engineering problems encountered for offshore wind turbines. A critical component is the connection of the structure to the ground, and in particular how the load applied to the structure is transferred safely to the surrounding soil. We review previous work on the design of offshore foundations, and then present some simple design calculations for sizing foundations and structures appropriate to the wind-turbine problem. We examine the deficiencies in the current design approaches, and the research currently under way to overcome these deficiencies. Designs must be improved so that these alternative energy sources can compete economically with traditional energy suppliers. PMID:14667305

  18. China offshore has top priority

    SciTech Connect

    Cornitius, T.A.

    1983-11-01

    Joint venture development of offshore petroleum reserves has top priority in the mammoth effort to modernize the People's Republic of China. While the country works to overcome a critical shortage of skilled personnel, export of oil, coal, consumer goods, and metals will finance technological imports.

  19. Stratigraphic setting of transgressive barrier-island reservoirs with an example from the Triassic Halfway Formation, Wembley field, Alberta, Canada

    SciTech Connect

    Willis, A.J.; Moslow, T.F. )

    1994-05-01

    Established models for landward barrier-island migration focus primarily on the preservation pattern of transgressive facies in the shoreface which are typically thin and buried beneath finer grained marine lower shoreface-to-offshore sediments. In contrast, transgressive barrier-island sandstones in the Triassic Halfway Formation of Wembley field in Alberta are preserved interbedded with, and overlain by, backbarrier and nonmarine sediments. These transgressive barrier sandstones formed from coalescing washover fans during shoreface retreat and were subsequently [open quotes]abandoned[close quotes] as the shoreline stabilized and resumed progradation. The abandoned transgressive barrier sandstones were subsequently blanketed by backbarrier and nonmarine sediments as the coastline continued to prograde. Abandoned transgressive barrier island sandstones in the Halfway Formation are 2-6 m thick, up to 2 km wide, and form paleocoastline-parallel trends tens of kilometers in length. The trends define the paleolandward limit of transgressive events. The updip pinch-out of these sandstones in backbarrier mudstones forms a stratigraphic trap for hydrocarbons in Wembley field. Top seal is provided by nonmarine mudstones and evaporites which buried and abandoned transgressive barrier island. The sandstone has porosities and permeabilities averaging 11% and 63 md, respectively. By using well logs and cores to correlate individual parasequences in the Halfway Formation to their updip termination, it is possible to define the extent of associated marine flooding events and therefore identify hydrocarbon exploration targets for abandoned transgressive barrier-island sandstones. 58 refs., 13 figs., 2 tabs.

  20. National Offshore Wind Energy Grid Interconnection Study

    SciTech Connect

    Daniel, John P.; Liu, Shu; Ibanez, Eduardo; Pennock, Ken; Reed, Greg; Hanes, Spencer

    2014-07-30

    The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States. A total of 54GW of offshore wind was assumed to be the target for the analyses conducted. A variety of issues are considered including: the anticipated staging of offshore wind; the offshore wind resource availability; offshore wind energy power production profiles; offshore wind variability; present and potential technologies for collection and delivery of offshore wind energy to the onshore grid; potential impacts to existing utility systems most likely to receive large amounts of offshore wind; and regulatory influences on offshore wind development. The technologies considered the reliability of various high-voltage ac (HVAC) and high-voltage dc (HVDC) technology options and configurations. The utility system impacts of GW-scale integration of offshore wind are considered from an operational steady-state perspective and from a regional and national production cost perspective.

  1. Tectono-stratigraphic signature of a rapid multistage subsiding rift basin in the Tyrrhenian-Apennine hinge zone (Italy): A possible interaction of upper plate with subducting slab

    NASA Astrophysics Data System (ADS)

    Milia, Alfonsa; Torrente, Maurizio M.

    2015-05-01

    The Campania Plain is a rapidly subsiding Quaternary basin that formed on the eastern margin of the Tyrrhenian Sea in association with the younger phase of Tyrrhenian rifting. It is located in the hinge area between the Apennines fold-thrust belt and the Tyrrhenian extensional backarc basin. By combining original stratigraphic analyses of well logs and seismic profiles we built a basin subsidence curve, mapped the fault pattern of the Campania Plain and analyzed the impact of the block faulting on the sedimentology and stratigraphic architecture of the basin fill. Well data indicate that the Quaternary succession consists of offshore, shoreface and coal-bearing coastal plain deposits arranged to form thick aggradational and retrogradational units. The sequence stratigraphy interpretation of well logs permitted us to recognize thirteen depositional sequences and the stratigraphic signatures of the rift stages. The study area corresponds to a sediment overfilled/balanced infill basin type that resulted from superposition of several rifting events characterized by high rates of basin subsidence. Taking into account the geological data of the adjacent areas, we propose a Pliocene-Quaternary rifting evolution of the upper Tyrrhenian plate consisting of four episodes. Two peculiar features of the Tyrrhenian rifting are a skip of the extensional axial zone eastwards leaving the previous zone of high strain localization (Vavilov basin), followed by a dramatic change (90) of the direction of extension. Because these Tyrrhenian features cannot be accounted for by the current rifting models we hypothesized a link between the evolution of upper plate and subducting slab. The proposed geodynamic scenario is characterized by a progressive rupture of the subducting plate and formation of extensional basins in the upper plate.

  2. A contribution to regional stratigraphic correlations of the Afro-Brazilian depression - The Dom Joo Stage (Brotas Group and equivalent units - Late Jurassic) in Northeastern Brazilian sedimentary basins

    NASA Astrophysics Data System (ADS)

    Kuchle, Juliano; Scherer, Claiton Marlon dos Santos; Born, Christian Correa; Alvarenga, Renata dos Santos; Adegas, Felipe

    2011-04-01

    The Dom Joo Stage comprises an interval with variable thickness between 100 and 1200 m, composed of fluvial, eolian and lacustrine deposits of Late Jurassic age, based mainly on the lacustrine ostracod fauna (although the top deposits may extend into the Early Cretaceous). These deposits comprise the so-called Afro-Brazilian Depression, initially characterized as containing the Brotas Group of the Recncavo Basin (which includes the Aliana and the Sergi Formations) and subsequently extended into the Tucano, Jatob, Camamu, Almada, Sergipe, Alagoas and Araripe Basins in northeastern Brazil, encompassing the study area of this paper. The large occurrence area of the Dom Joo Stage gives rise to discussions about the depositional connectivity between the basins, and the real extension of sedimentation. In the first studies of this stratigraphic interval, the Dom Joo Stage was strictly associated with the rift phase, as an initial stage (decades of 1960-70), but subsequent analyses considered the Dom Joo as an intracratonic basin or pre-rift phase - without any relation to the active mechanics of a tectonic syn-rift phase (decades of 1980-2000). The present work developed an evolutionary stratigraphic and tectonic model, based on the characterization of depositional sequences, internal flooding surfaces, depositional systems arrangement and paleoflow directions. Several outcrops on the onshore basins were used to build composite sections of each basin, comprising facies, architectural elements, depositional systems, stratigraphic and lithostratigraphic frameworks, and paleocurrents. In addition to that, over a hundred onshore and offshore exploration wells were used (only 21 of which are showed) to map the depositional sequences and generate correlation sections. These show the characteristics and relations of the Dom Joo Stage in each studied basin, and they were also extended to the Gabon Basin. The results indicate that there were two main phases during the Dom Joo Stage, in which distinctive sedimentary environments were developed, reflecting depositional system arrangements, paleoflow directions were diverse, and continuous or compartmented basins were developed.

  3. Offshore Renewable Energy R&D (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    This fact sheet describes the offshore renewable energy R&D efforts at NREL's NWTC. As the United States increases its efforts to tap the domestic energy sources needed to diversify its energy portfolio and secure its energy supply, more attention is being focused on the rich renewable resources located offshore. Offshore renewable energy sources include offshore wind, waves, tidal currents, ocean and river currents, and ocean thermal gradients. According to a report published by the National Renewable Energy Laboratory (NREL) in 2010,1 U.S. offshore wind resources have a gross potential generating capacity four times greater than the nation's present electric capacity, and the Electric Power Research Institute estimates that the nation's ocean energy resources could ultimately supply at least 10% of its electric supply. For more than 30 years, NREL has advanced the science of renewable energy while building the capabilities to guide rapid deployment of commercial applications. Since 1993, NREL's National Wind Technology Center (NWTC) has been the nation's premier wind energy research facility, specializing in the advancement of wind technologies that range in size from a kilowatt to several megawatts. For more than 8 years, the NWTC has been an international leader in the field of offshore floating wind system analysis. Today, researchers at the NWTC are taking their decades of experience and extensive capabilities and applying them to help industry develop cost-effective hydrokinetic systems that convert the kinetic energy in water to provide power for our nation's heavily populated coastal regions. The center's capabilities and experience cover a wide spectrum of wind and water energy engineering disciplines, including atmospheric and ocean fluid mechanics, aerodynamics; aeroacoustics, hydrodynamics, structural dynamics, control systems, electrical systems, and testing.

  4. Alternating Authigenic and Carbonate Factory Production within a Cool-water Carbonate Sequence Stratigraphic Framework

    NASA Astrophysics Data System (ADS)

    Thompson, N. K.; Reid, C.; Bassett, K. N.

    2012-12-01

    Glaucony and phosphate production is characteristic of low sedimentation rates within low energy, oxygen-depleted environments, and is often associated with condensed sections and unconformities. Glaucony- and phosphate-rich rocks are often interpreted to be associated with sea-level highstands and maximum flooding surfaces, especially in siliciclastic systems. In contrast, our research shows that in the cool-water carbonate realm glaucony and, to an extent, phosphate are connected to lowstands and transgressions, requiring a reversal in the way they are interpreted within a sequence stratigraphic context. The Mid-Tertiary rocks of the Waitaki Basin, South Island, New Zealand, contain a cool-water carbonate and greensand succession formed on the eastern passive margin of the Zealandia continental fragment, and include two major sequence boundaries within a broad regional transgression. The palaeobasin contained an eastern outer shelf volcanic-induced high that acted like a platform rim, from where the basin deepened towards the west. The basal sequence contains a bryozoan grainstone facies that formed a shoal on the eastern volcanic seamount. This grades westward to a quartzose impure wackestone containing terrigenous material derived from low-lying islands of Zealandia far to the west. The overlying sequence boundary forms a karst surface associated with the high in the east, and a firmground in the west, and developed as a result of sea-level fall and lowstand conditions. During these lowstand conditions the terrigenous supply of silt and clay material was moved closer to the Waitaki Basin and this was then available for glauconitisation. Calcareous glaucony- and phosphate-rich greensands accumulated during the subsequent transgression, with the glaucony and phosphate content decreasing through this second sequence to form pure packstones during highstand and early regression. The second sequence boundary overlying these packstones shows similar karst and firmground distribution to the first, and has a similar greensand transgressive sequence deposited above it. In this cool-water setting, where the carbonate factory is located on an offshore volcanic-induced high, authigenic mineral production occurs at lowstand settings. During lowstand, mud-sized terrigenous clay minerals are introduced to the basin from the west, smothering the carbonate factory and supplying the building blocks for glaucony production. Through the transgressive phase this terrigenous clay supply is progressively shut down and the system returns to carbonate production at highstand. Sea-level rise in such an environment encourages the development of the cool-water carbonate factory, and thus a decrease in production from the 'authigenic factory'.

  5. Quaternary Seismic Stratigraphic Framework of the Northern North Carolina Inner Continental Shelf

    NASA Astrophysics Data System (ADS)

    Foster, D. S.; Thieler, E. R.; Capone, M. K.; Denny, J. F.

    2002-12-01

    The U.S. Geological Survey has recently collected high-resolution Boomer and CHIRP seismic-reflection profiles along the inner continental shelf of North Carolina between False Cape, VA and Cape Hatteras, NC. The two systems were used concurrently on a dense survey grid with shore parallel lines spaced about 300 m apart. Tie lines were run perpendicular to shore and were spaced about 4 km apart. The survey area covers the inner shelf from about the 7-m isobath to 11 km offshore. Boreholes were drilled on the barrier islands to provide ground truth and correlate the seismic stratigraphy mapped on the shelf and in the backbarrier estuary. Seismic interpretations on the inner shelf are being verified with vibracore data. At least five transgressive unconformities are observed as planar reflections that dip to the southeast. The seismic sequences bounded by these unconformities also thicken slightly to the southeast. As a result, the Quaternary stratigraphic section is more compressed in the northern part of the study area. The deepest unconformity is believed to be the top of the Yorktown Formation (Pliocene) and is recognized as a distinct angular unconformity on Boomer profiles in the northern part of the study area. Three shallower unconformities have been identified on the Boomer profiles, which can be related to discrete Pleistocene sea-level fluctuations using amino acid racemization chronologies. In addition to these surfaces, the Holocene transgressive unconformity is best identified on the Chirp profiles. However, for much of the study area there is no definitive seismic reflection where we believe the unconformity should be located, based on lithologic contacts in vibracores. In some areas, there is a strong seismic reflection that correlates to the base of a mud unit that is most likely pre-Holocene back-barrier lagoon deposits. Accurate mapping of Recent marine sands requires integrating Chirp data with vibracores. There are several areas of fluvial cut and fill that partially remove older Pleistocene units and truncate some of the transgressive unconformities. The paleo-Roanoke River valley complex is the most extensive seen on the seismic profiles. The relative ages of smaller fluvial channel complexes to the north and south cannot be linked with the main Roanoke channel complex based on the geophysical data alone. Radiocarbon ages from onshore boreholes indicate the channel complex was cut during at least two late Pleistocene lowstands.

  6. Stratigraphic records of paleogeography and global change from two late Proterozoic basins

    NASA Astrophysics Data System (ADS)

    Swanson-Hysell, Nicholas L.

    As sediments and volcanic deposits accumulate on Earth's surface, they record information about Earth's climate, the motion of continents, and the evolution of the biosphere. Through the study of ancient stratigraphic sequences, we can gain a window into our planet's varied, and sometimes tumultuous, past. In this dissertation, I employ a combination of field observations, magnetic data, and chemostratigraphic data in the Keweenawan Mid-continent Rift of North America and the Amadeus Basin of Central Australia to study the paleogeography and paleoclimate during and after the transition between the Mesoproterozoic (1.7 to 1.0 billion-years ago) and Neoproterozoic Eras (1.0 to 0.54 billion-years ago). The supercontinent Rodinia formed at the boundary between the Eras and broke apart throughout the Neoproterozoic. Basins that developed as Rodinia rifted apart record large changes in the biogeochemical cycling of carbon and sulfur, the waxing and waning of low-latitude ice sheets, and the progressive oxygenation of the atmosphere that facilitated the evolution of animals. I report high-resolution paleomagnetic data in stratigraphic context from Mamainse Point, Ontario---the most complete succession in the 1.1 billion-year-old Mid-continent Rift. The results demonstrate that previous suggestions of large non-dipolar geomagnetic field components at the time stemmed from low temporal resolution across geomagnetic reversals during a period of rapid plate motion. This result strengthens the framework for evaluating records of tectonics and climate across the Mesoproterozoic/Neoproterozoic boundary. Rock magnetic experiments on Mamainse Point lavas, paired with electron microscopy, demonstrate that a component of the magnetization in oxidized flows that is antiparallel to the characteristic remanence is a result of martite self-reversal. This component is the best resolved natural example of the experimentally observed self-reversal that accompanies the maghemite to hematite transition. This result allows the magnetizations of the lavas to be fully interpreted, and also suggests that this self-reversal phenomena may be more widespread than currently recognized---with its identification in this study being greatly aided by stratigraphic context during a period when North America was moving rapidly towards the equator. Stratigraphic and stable isotope work on the Neoproterozoic Bitter Springs Formation of the Amadeus Basin demonstrates that the negative carbon isotope values of the "Bitter Springs Stage" are tightly consistent in carbonate rocks across more than 400 km. In addition to being present in the isotopic composition of the carbonate, organic carbon isotope values shift sympathetically into and out of the stage thereby supporting the interpretation that the stage is a record of primary changes to the carbon cycle. The stage is bound by sequence boundaries that provide evidence for changes in sea-level and climate. Previous work on correlative stratigraphy from the Akademikerbreen Group of East Svalbard (Maloof et al., 2006), revealed changes in relative sea-level and paleomagnetic directions that have were interpreted to have resulted from a pair of large-scale true polar wander events. In an effort to further test this hypothesis, and to remedy a lack of paleogeographic constraints for north Australia in the early Neoproterozoic, I present paleomagnetic data from more than 630 paleomagnetic samples of carbonates, siltstones and basalt flows from the Bitter Springs Formation. A new reliable pole from post-Bitter Springs Stage siltstones provides strong support for a recently published hypothesis that there was relative rotation between north and south+west Australia in the late Neoproterozoic (Li and Evans, 2011), and for the long-standing hypothesis that Australia and Laurentia were cotravelers in Rodinia into the mid-Neoproterozoic Era. The difference between the paleomagnetic poles of syn-Bitter Springs Stage carbonates and post-Bitter Springs Stage siltstones is likely a result of a Cambrian remagnetization of

  7. The 1911 Quadrant offshore Namibia; Exploration in a virgin basin

    SciTech Connect

    Holtar, E.; Forsberg, A.

    1995-08-01

    As a result of the first licensing round in independent Namibia, the Namibian authorities in 1992 awarded five offshore licenses to five different companies or groups of companies. License no. 001 was awarded in 1992 to a group consisting of three Norwegian oil companies, Norsk Hydro, Saga Petroleum and Statoil, with Hydro as the operator. Somewhat later Bow Valley Energy (now Talisman Energy) farmed in. Since 1992 a seismic survey of 7200 km has been acquired over the license area that covers 11.619 sq. Km of the Walvis Basin. This basin was undrilled until the 1911/15-1 well was finished at a depth of 4586mRKB in early 1994. The sedimentary succession of the 1911/15-1 well reflects a depositional history that postdates the Neocorman Etendeka plateau basalts found onshore Namibia. After the onset of the drift phase in late Hauterivian times, the Walvis Basin subsided and eventually a marine transgression took place. Shallow marine platform sedimentation then prevailed until an Albian tectonic event resulted in complex block faulting and the formation of several sub basins. Subsequent volcanic activity created a series of volcanic centres localized on the Walvis Ridge bathymetric feature. In early Late Cretaceous the Southern African craton was uplifted relative to the shelf, leading to the formation of large scale westward prograding wedges. Later sedimentation largely followed the evolution of a passive continental margin, responding to relative sealevel changes and paleoclimate. A stratigraphic breakdown of the Northern Namibian offshore is proposed, and compared to South African and Angolan nomenclature.

  8. Horizontal drilling in the Austin Chalk: Stratigraphic factors

    SciTech Connect

    Durham, C.O. Jr. ); Bobigian, R.A. )

    1990-05-01

    Horizontal drilling has renewed interest in the Austin chalk in south-central Texas. Large fields on opposite sides of the San Marcos arch Giddings to the northeast and Pearsall to the southwest were active with vertical drilling 10 years ago. Giddings' 4,500 Austin wells produced 209 million BO and 934 bcfg of gas through 1988; Pearsall's 1,440 wells produced 57 million BO and 35 bcfg of gas. Most vertical wells were completed, 20% were economic successes, 40% were marginal, 40% were uneconomic due to uneven areal distribution of near-vertical fractures and small faults, which provide reservoirs in otherwise tight chalk. Horizontal drilling, led by Amoco in Giddings and Oryx in Pearsall, enhances the chances of encountering the fractures by drilling perpendicular to the fracture trend. Horizontal drilling requires preselection of the stratigraphic horizon to be penetrated. One must understand the variable Austin stratigraphy to choose the zone with the most brittle character and best matrix porosity, both reduced by increased clay content. Chalk 130 ft thick on the San Marcos arch thickens to 600 to 800 ft in central Giddings field where middle marl separates lower and upper chalk Northeastward only lower chalk is preserved beneath a post-Austin submarine channel. The Austin thickens to 300-500 ft in Pearsall field where middle member ash beds separate lower and upper chalk inhibiting vertical reservoir communication. Locally, on the Pearsall arch, ash is missing, lower chalk thickens, and upper chalk thins.

  9. Upper Paleozoic stratigraphic sequences in the Western Interior, USA

    SciTech Connect

    Maughan, E.K.; Macke, D.L.

    1993-04-01

    Major depositional sequences in the upper Paleozoic (Mississippian through Permian) of the Western Interior reflect either tectonism, eustatic sea-level change, or both. The stratigraphic sequences approximate (1) the Lower Mississippian Lodgepole Limestone of the Madison Group, (2) the Lower and Upper Mississippian Mission Canyon Limestone in the Madison Group, (3) the Upper Mississippian Big Snowy Group, (4) the Lower and Middle Pennsylvanian Amsden Group, (5) the Middle Pennsylvanian and Lower Permian Minnelusa Group, and (6) the Middle and Upper Permian Park City Group. These upper Paleozoic sequences in the Western Interior seem to be intricately related to similar, third-order transgressive-regressive cycles in the Cordilleran region, but precise relationships of some sequence boundaries remain to be determined. Parasequence sets evidence minor eustatic oscillations within these six major Western Interior sequences. The widespread paraconformable contact between Permian and overlying Triassic strata on the Wyoming shelf indicates that this sequence boundary resulted primarily from eustatic marine regression. Overall, the upper Paleozoic sequences of the Western Interior were deposited in a stable epeirogenic framework that succeeded Devonian tectonism but were diastrophically affected again during the Pennsylvanian. The timing of these diastrophic events in the Western Interior seem to coincide with plate collision events along the eastern and southern margins of North America, but eustatic changes may be related to other causes.

  10. Basal Murphy belt and Chilhowee Group -- Sequence stratigraphic comparison

    SciTech Connect

    Aylor, J.G. Jr. . Dept. of Geology)

    1994-03-01

    The lower Murphy belt in the central western Blue Ridge is interpreted to be correlative to the Early Cambrian Chilhowee Group of the westernmost Blue Ridge and Appalachian fold and thrust belt. Basal Murphy belt depositional sequence stratigraphy represents a second-order, type-2 transgressive systems tract initiated with deposition of lowstand turbidites of the Dean Formation. These transgressive deposits of the Nantahala and Brasstown Formations are interpreted as middle to outer continental shelf deposits. Cyclic and stacked third-order regressive, coarsening upwards sequences of the Nantahala Formation display an overall increase in feldspar content stratigraphically upsection. These transgressive siliciclastic deposits are interpreted to be conformably overlain by a carbonate highstand systems tract of the Murphy Marble. Palinspastic reconstruction indicates that the Nantahala and Brasstown Formations possibly represent a basinward extension of up to 3 km thick siliciclastic wedge. The wedge tapers to the southwest along the strike of the Murphy belt at 10[degree] and thins northwestward to 2 km in the Tennessee depocenter where it is represented by the Chilhowee Group. The Murphy belt basin is believed to represent a transitional rift-to-drift facies deposited on the lower plate of the southern Blue Ridge rift zone.

  11. Eolian paleotopographic highs as stratigraphic traps: origin and distinction

    SciTech Connect

    Eschner, T.B.; Kocurek, G.A.

    1985-02-01

    Significant hydrocarbon accumulations occur where eolian paleotopographic highs are preserved beneath transgressive marine deposits. Paleotopographic highs can represent erosional remnants of an unconformity, or partly preserved eolian dunes, or combinations of both. Paleotopography reflects the extent of modification undergone by eolian units prior to or during transgression. Modification varies between extremes of (1) destruction - where eolian deposits are deeply eroded and the former dunal profile is lost, and (2) preservation - where dunes and interdune areas are preserved nearly intact. The extent of modification that occurs during transgression is controlled primarily by (1) the energy of the transgressing sea, (2) the speed of transgression, and (3) the abundance of sand-stabilizing early cements or plants. High-energy seas destroy dunes through persistent erosion by tides and waves and by initiating dune collapse and mass flowage of dune sands. Preservation occurs where quiescent seas flood interdune areas and create shallow to periodically emergent marine environments, such as interdune sabkhas or tidal flats. Gradual filling of interdune areas with shallow marine sediments can fortify and preserve adjacent dunes. These varied processes that interact between marine and eolian environments to create different types of topography are exemplified in ancient eolian-marine sequences of the Western Interior of North America, and preserved Holocene dunes of coastal Australia. Different types of eolian highs can be recognized by analysis of bounding surfaces in outcrop or core. An understanding of eolian-marine processes and environments that create topography allows for prediction of areas of potential stratigraphic traps.

  12. Seismic stratigraphic framework of deep central Gulf of Mexico basin

    SciTech Connect

    Shaub, F.J.; Buffler, R.T.; Parsons, J.G.

    1984-11-01

    The deep Gulf of Mexico basin is underlain by up to 10 km (33,000 ft) of Jurassic(.) to Holocene layered sedimentary rocks. The multichannel reflection seismic record from the deep Gulf of Mexico was divided into six seismic stratigraphic units for study of the geologic history of this accumulation. The basal Challenger unit (Jurassic (.) to middle Cretaceous) is considered coeval with early basin formation. We interpret it as a deep marine sequence overlying oceanic crust in the central basin and as continental and shallow through deep marine rocks, including thick evaporites, over adjacent transitional crust. The next three units, Campeche, Lower Mexican Ridges and Upper Mexican Ridges, indicate that from the Late Cretaceous through middle Miocene the basin filled progressively from the west and north, most probably with siliceous turbidites interlayered with pelagic deposits. By the late Tertiary, however, salt and shale deformation within thick sedimentary sections along the western and northern margins trapped much of the incoming sediment supply on the shelves and upper slopes. The late Miocene to Pliocene Cinco de Mayo unit, therefore, represents a relatively starved interval. In contrast, the uppermost, or Sigsbee unit, includes the Mississippi Fan, an accumulation up to 3 km (10,000 ft) thick of mainly mass-transported deposits that bypassed the shelf and slope and were deposited directly onto the abyssal plain. In the western and southwestern portions of the deep basin, beyond the fan pinchout, the Pleistocene section is largely a continuation of the Pliocene suspension deposits.

  13. The ocean-continent transition zones: Stratigraphic and paleoecosystem studies

    SciTech Connect

    Gladenkov, Yu.B. )

    1993-03-01

    The author uses the Cenozoic of the Russian Pacific coast, drawing particularly on his 30-year experience with the molluscan faunas, as the source of examples of the ways that regional and global changes in the inorganic world affect the living world, as reflected in the stratigraphic and paleontologic record. The shelf ecosystem, despite its relative stability, shows periods of rapid change, reflecting both migration and accelerated evolution. The shelf ecosystem of the boreal belt evolved during Cenozoic time in an environment of changing paleoclimatic and paleogeographic phenomena. In spite of all their complexity and the considerable stressed nature of situations during individual moments in geological time, the ecosystem displayed a relative stability. The composition and structure of biotic communities, judging by the mollusks, changed with a definite trend (since Oligocene time, mainly on the species level), with gradual replacement through time of some forms by others, and with an increase in the percentage of Holocene species. This linear process was complicated by moments when the process accelerated. The problems encountered require wider discussion. The observed patterns of development of abiotic and biotic phenomena in this region, with its definite cyclicity and synchroneity, may be valuable in deciphering such patterns in other regions of the globe. The trends seen in the evolution of the biotic communities during Cenozoic time may also provide a basis for predicting the development of shelf ecosystems in the forthcoming decades and centuries. 46 refs., 2 figs., 2 tabs.

  14. The Cook Mountain problem: Stratigraphic reality and semantic confusion

    SciTech Connect

    Ewing, T.E.

    1994-12-31

    Historical inconsistency as to what constitutes the Cook Mountain Formation illustrates the semantic confusion resulting from extending surface-derived stratigraphic names into the subsurface without a full understanding of basin architecture. At the surface, the Cook Mountain Formation consists of fossilerous marine shale, glaucony and marl, and marginal-marine sandstone and shale between the nonmarine Sparta Formation sandstones below and the nonmarine Yegua Formation sandstones and lignitic shales above. Fossils are abundant, including the benthic foraminifer Ceratobulimina eximia. As subsurface exploration began, the first occurrence of Ceratobulimina eximia {open_quotes}Cerat{close_quotes} was used as the top of the marine {open_quotes}Cook Mountain Shale{close_quotes} below the Yegua section. Downdip, the overlying Yegua was found to become a sequence of marine shales and marginal-marine sandstones, the lower part of which yielded {open_quotes}Cerat{close_quotes}. Because of this, the lower sandstones were called {open_quotes}Cook Mountain{close_quotes} in many fields. At the Yegua shelf margin, {open_quotes}Cerat{close_quotes} is absent. Different exploration teams have used their own definitions for {open_quotes}Cook Mountain{close_quotes}, leading to substantial confusion.

  15. Stratigraphic variation of sulfur isotopes in Colorado Corehole Number 1

    SciTech Connect

    Smith, J.W.; Young, N.B.

    1983-04-01

    Sulfur isotope distribution with stratigraphy is reported for organic and pyritic sulfur of Green River Formation oil shale samples selected to represent the 1600-foot (488 m) Parachute Creek Member in Colorado Corehole No. 1. In the saline zone where nahcolite and dawsonite occur in the oil shale and in the Mahogany zone the /sup 34/ values for organic sulfur and pyrite sulfur match with the pyrite sulfur slightly lighter than the organic sulfur. This is interpreted to demonstrate that organic matter supplied most of the sulfur to the sediment which became oil shale. Little sulfate reached the sediment so no sulfate reduction could occur to enrich the heavy sulfur isotope. No systematic increase in S/sup 34/ was detected in either pyrite or organic sulfur. A remarkably large increase in concentration of /sup 34/S occurring in a short stratigraphic span is demonstrated. This abrupt increase occurs near the middle of the Parachute Creek Member sediments. Above this point both pyrite and organic sulfur remain significantly enriched in /sup 34/S.

  16. Pleistocene sediments of Lake Baikal: Lithology and stratigraphic correlation

    NASA Astrophysics Data System (ADS)

    Akulov, N. I.; Mashchuk, I. M.; Akulova, V. V.

    2015-01-01

    The Cenozoic sediments of Lake Baikal penetrated by boreholes and investigated by the manned submersible Pisces, as well as coeval deposits cropping out in beach scarps, recovered by mine workings, and drilled in the coastal zone were the object of this investigation. The main attention was paid to Pleistocene bottom sediments penetrated by Borehole BDP-99-2. The investigations included the detailed analysis of the lithology (grain-size composition, immersion mineralogy of light and heavy fractions, X-ray structural analysis of clayey fraction) and palynological assemblages to specify facies features of Cenozoic sediments, correlate all their known stratigraphic units constituting the sedimentary section of the lake with their analogs in the onshore part of the Baikal rift zone, and compile the composite Cenozoic section. The following features of these sediments are noted: (1) as a whole, Pleistocene sediments are characterized by the hydromica-smectite composition of their clayey fraction with an insignificant share of kaoline; (2) the heavy fraction is dominated by the terrigenous epidote-amphibole association poorly resistant to weathering; (3) Pleistocene sediments of the lake contain siderite, vivianite, pyrite, and goethite concretions and micrometeorites, in addition to well-known ferromanganese nodules; (4) the presence of relict palynomorphs in Pleistocene sediments of Baikal is determined by their erosion from Miocene and Pliocene cavernous clays cropping out on underwater slopes of the Posol'skaya Bank and subsequent reburial along with Pleistocene palynological assemblages.

  17. Two offshore Australian crudes assayed

    SciTech Connect

    Rhodes, A.K.

    1994-05-09

    Two light, sweet crudes from offshore Australia have been assayed. Gippsland crude, also called Bass Strait, is produced off the coast of Victoria, in southeastern Australia. The 47 API, 0.09% sulfur crude was analyzed in mid-1993. Skua, a 42 API, 0.06 wt % sulfur crude, is produced in the Timor Sea. Data are given on the whole crude and fractions for both deposits. Both chemical and physical properties are listed.

  18. Fatigue handbook: Offshore steel structures

    SciTech Connect

    Almarnaess, A.

    1985-01-01

    The contents of this book are: Overview of Offshore Steel Structures; Loads on Ocean Structures; Fracture Mechanics As a Tool in Fatigue Analysis; Basic Fatigue Properties of Welded Joints; Significance of Defects; Improving the Fatigue Strength of Welded Joints; Effects of Marine Environment and Cathodic Protection on Fatigue of Structural Steels Fatigue of Tubular Joints; Unstable Fracture; Fatigue Life Calculations; and Fatigue in Building Codes Background and Applications.

  19. Offshore sand and gravel mining

    SciTech Connect

    Pandan, J.W.

    1983-05-01

    This paper reviews the status of mining offshore for sand and gravel on a world-wide basis. It discusses the technology for exploration and evaluation of sea floor mineral targets, as well as mining, transportation, and processing. Large operations in Japan and Europe are described, based upon personal observations of the author. The U.S. situation is outlined and opinions offered as to the outlook for the future.

  20. Offshore platform system and method

    SciTech Connect

    Roach, R.T.

    1983-03-29

    An offshore platform structure and a system for transport and for reversible erection is disclosed. The light weight, semimobile structure; has negative buoyancy; is free standing on the ocean floor; has fixed guylines below interference depth and quickly positioned upper guylines for storm conditions; the structure may contain suitable tanks in the base for production of marginal crude oil wells or other fluid storage; a special tender to furnish buoyancy during transport.

  1. Pipelaying in artic offshore waters

    SciTech Connect

    Langner, C. G.

    1985-11-19

    The present invention provides a method and apparatus for constructing pipelines in Arctic offshore waters by a directional drilling technique, thereby minimizing exposure to ice gouging and eliminating the hazards associated with unstable permafrost. A special drilling-pipe-line construction vessel is also provided which has a conical shape with reinforced outer walls to resist ice forces, which vessel includes means to install deep underground pipeline segments and means to connect and protect the pipe ends.

  2. Fossils out of sequence: Computer simulations and strategies for dealing with stratigraphic disorder

    SciTech Connect

    Cutler, A.H.; Flessa, K.W. )

    1990-06-01

    Microstratigraphic resolution is limited by vertical mixing and reworking of fossils. Stratigraphic disorder is the degree to which fossils within a stratigraphic sequence are not in proper chronological order. Stratigraphic disorder arises through in situ vertical mixing of fossils and reworking of older fossils into younger deposits. The authors simulated the effects of mixing and reworking by simple computer models, and measured stratigraphic disorder using rank correlation between age and stratigraphic position (Spearman and Kendall coefficients). Mixing was simulated by randomly transposing pairs of adjacent fossils in a sequence. Reworking was simulated by randomly inserting older fossils into a younger sequence. Mixing is an inefficient means of producing disorder; after 500 mixing steps stratigraphic order is still significant at the 99% to 95% level, depending on the coefficient used. Reworking disorders sequences very efficiently: significant order begins to be lost when reworked shells make up 35% of the sequence. Thus a sequence can be dominated by undisturbed, autochthonous shells and still be disordered. The effects of mixing-produced disorder can be minimized by increasing sample size at each horizon. Increased spacing between samples is of limited utility in dealing with disordered sequences: while widely separated samples are more likely to be stratigraphically ordered, the smaller number of samples makes the detection of trends problematic.

  3. Offshore oil: Correctness of perspective

    SciTech Connect

    Burns, R.F.

    1993-05-01

    Except for the Gulf of Mexico, the offshore oil industry has been virtually banned from the US Exclusive Economic Zone for ten years. The oil potential in Alaska's Arctic National Wildlife Refuge (ANWR) is also off limits. The Gulf of Mexico is the only place with prospects for future success and a number of companies both large and small are determined to move forward. The depressed price of oil does not encourage development but recently gas prices in the US have increased, making offshore gas development more feasible. Perhaps most significant is development and application of new technology and more intense management to make sure it works. The offshore oil companies and support industries have made significant technological advances, expending over and above the dollars paid in taxes, lease fees, and royalties. The ocean industries harbor a great reservoir of high technology knowledge. They have demonstrated the ability to successfully meet a vast array of challenges in exploring for, drilling, and producing oil and gas in extreme conditions. These facts beg the question as to the rational basis of each and every regulation and the ban on drilling.

  4. Integrated onshore-offshore investigation of a Mediterranean layered coastal aquifer.

    PubMed

    Lofi, Johanna; Pezard, Philippe; Bouchette, Frdric; Raynal, Olivier; Sabatier, Pierre; Denchik, Nataliya; Levannier, Arnaud; Dezileau, Laurent; Certain, Raphal

    2013-01-01

    Most of the Mediterranean coastal porous aquifers are intensively exploited. Because of climatic and anthropogenic effects, understanding the physical and geological controls on groundwater distribution and flow dynamics in such aquifers is crucial. This study presents the results of a structural investigation of a system located along the coastline of the Gulf of Lions (NW Mediterranean). A key aspect of this study relies on an onshore-offshore integrated approach combining outcrops, seismic profiles, and borehole data analysis. This multidisciplinary approach provides constraints on pore-fluid salinity distribution and stratigraphic organization, which are crucial in assessing the modes of groundwater/seawater exchanges. Onshore, Lower Pliocene deposits dip gently seaward. They are unconformably overlain by Holocene clays in the lagoons. Offshore the Pliocene deposits either outcrop at the seabed or are buried below nonconsolidated sands infilling paleo-valleys. Beneath the lido, the groundwater salinity distribution consists of salty pore water, overlying fresher pore water. Active circulation of groundwater masses is inferred from the geophysical results. In particular, offshore outcrops and paleo-valleys may play an important role in salt water intrusion. PMID:23163402

  5. The oligocene stratigraphic framework of the coastal plain of the southeastern United States

    SciTech Connect

    Huddlestun, P.F. )

    1993-03-01

    Four lithostratigraphic associations are recognized in the Oligocene of the southeastern Coastal Plain: (1) an eastern Gulf of Mexico stratigraphic association, (2) a Gulf Trough stratigraphic association, (3) a Florida Bank stratigraphic association and (4), an Atlantic continental shelf stratigraphic association. Oligocene formations and faunal provinces appear to be directly related to the stratigraphic associations. The Vicksburg Group is restricted to the eastern Gulf of Mexico continental shelf stratigraphic association and to the Coastal Plain north and west of the Gulf Trough. The Gulf Trough stratigraphic association includes the Ochlockonee Formation, Wolf Pit Dolostone, Okapilco Limestone, and Bridgeboro Limestone (the Bridgeboro Limestones occurs only on and adjacent to the northern and southern flanks of the trough). The Florida Bank stratigraphic association is largely restricted to the area south of the Gulf Trough and includes the Ellaville Limestone, Suwannacoochee Dolostone, and Suwannee Limestone (the Suwannee Limestone also occurs immediately north of the Gulf Trough in the central Georgia Coastal Plain). The Cooper and Lazaretto Creek Formations are restricted to the Atlantic continental shelf stratigraphic association and occur only in the coastal area of Georgia, South Carolina, and beneath the continental shelf. Three faunal provinces (or subprovinces) are recognized in the southeastern Coastal Plain during the Oligocene: (1) a Gulf of Mexico continental shelf faunal province that characterizes the Gulf Trough and the region north and west of the trough, (2) a Florida province characteristic and largely restricted to the Florida Bank and (3), an Atlantic continental shelf faunal province. Through the Early Oligocene, the trough marked the limits of the Gulf of Mexico and Florida provinces.

  6. A Proposed Time-Stratigraphic System for Protoplanet Vesta

    NASA Astrophysics Data System (ADS)

    Williams, David; Jaumann, Ralf; McSween, Harry; Raymond, Carol; Russell, Chris

    2014-05-01

    The Dawn Science Team completed a geologic mapping campaign during its nominal mission at Vesta, including production of a 1:500,000 global geologic map derived from High-Altitude Mapping Orbit (HAMO) images (70 m/pixel) [1] and 15 1:250,000 quadrangle maps derived from Low-Altitude Mapping Orbit (LAMO) images (20-25 m/pixel) [2]. In this abstract we propose a time-stratigraphic system and geologic time scale for the protoplanet Vesta, based on global geologic mapping and other analyses of NASA Dawn spacecraft data, supplemented with insights gained from laboratory studies of howardite-eucrite-diogenite (HED) meteorites and geophysical modeling. Our time-stratigraphic system for Vesta relates the geologic map (rock) units identified from geologic mapping to a series of time-rock units and corresponding time units that define a geologic time scale for Vesta. During the Dawn nominal mission it became clear that the south pole of Vesta hosts two large impact basins, the older Veneneia superposed by the younger Rheasilvia [3,4]. Two separate sets of large ridges and troughs were identified, one set encircling much of Vesta equatorial region (Divalia Fossae), and the other preserved in the heavily cratered northern terrain (Saturnalia Fossae). Structural analysis of these ridge-and-trough systems demonstrated that they are likely a tectonic response to the formation of the south polar basins: the Rheasilvia impact led to the formation of the Divalia Fossae, the Veneneia impact led to the Saturnalia Fossae [3,5]. Crater counts provide cratering model ages for the Rheasilvia impact of ~3.6 Ga and ~1 Ga, and ages for the Veneneia impact of ~3.8 Ga and >2.1 Ga using the lunar-derived and asteroid flux-derived chronologies, respectively. Despite the differences in absolute ages, it is clear that these two large impact events had global effects, and thus delineate the major periods of Vesta's geologic history. Zones of heavily cratered terrain (HCT: [6,7]) in the northern hemisphere adjacent to the Saturnalia Fossae Formation [1] likely are heavily modified portions of Vesta's ancient crust. The geologic units in and around the 68 x 58 km Marcia crater appear to delineate the most recent large impact event on Vesta. Crater counts of areas of the Marcia ejecta blanket give cratering model ages of ~120-150 Ma and ~220-390 Ma using the lunar-derived and asteroid flux-derived chronologies, respectively [6-8]. References: [1] Yingst, R.A., et al. (2014) PSS, in press. [2] Williams, D.A., et al. (2014a) Icarus, in review. [3] Jaumann, R. et al. (2012) Science 336, 687-690. [4] Schenk, P. et al. (2012) Science 336, 694-697. [5] Buczkowski, D.L. et al. (2013) GRL 39, L18205, doi:10.1029/2012GL052959. [6] Marchi, S. et al. (2012) Science 336, 690-694. [7] Schmedemann, N. et al. PSS (in revision). [8] Williams, D.A. et al. (2014b) Icarus, in revision.

  7. The history of tectonism on Venus: A stratigraphic analysis

    NASA Astrophysics Data System (ADS)

    Ivanov, Mikhail A.; Head, James W.

    2015-08-01

    The surface of Venus displays several tectonized terrains in which the morphologic characteristics of the original materials are almost completely erased by superposed tectonic structures whose large dimensions (100 km) suggest formation related to mantle convection. The characteristics of these tectonized terrains are in contrast to volcanic units in which tectonic structures are less significant or absent and thus do not obscure the volcanic character of the units. We describe the temporal distribution of tectonized terrains, their stratigraphic relationships with volcanic units, and how these outline the major episodes in the geological evolution of Venus. Five major tectonized units make up ~20% of the planet: (1) tessera (t, 7.3%), (2) densely lineated plains (pdl, 1.6%), (3) ridged plains/ridge belts (pr/rb, 2.4%), (4) groove belts (gb, 8.1%), and (5) rift zones (rz, 5.0%). Clear relationships of relative age are often seen among the tectonic and volcanic units at the global scale and define three contrasting regimes of volcanic and tectonic resurfacing. The majority of tectonized terrains (t through gb) are the products of tectonic resurfacing and are embayed by the vast volcanic plains and, thus, are older. There are no units with either mildly- or non-tectonized surfaces that interleave the tectonic terrains, which would be expected if the tectonic resurfacing operated only during specific repetitive phases in discrete regions. These tectonized terrains (t through gb) thus define a tectonically dominated regime of resurfacing that occurred at a global-scale near the beginning of the observable geological history of Venus. This ancient tectonic regime began with formation of tessera and was followed by formation of pdl and pr/rb. Groove belts formed near the end of this regime. Branches of groove belts compose the tectonic components of many coronae, suggesting that these features are genetically related (e.g., mutual development of mantle diapirs and zones of extension) and that coronae may have punctuated the final stages of the ancient tectonic regime. This regime was followed by emplacement of the vast volcanic plains, such as shield and regional plains, the surfaces of which are extensively deformed by the global network of wrinkle ridges. Emplacement of the plains defines the second, volcanically dominated regime, representing a time when surface tectonic deformation related to the mantle convection waned. Rift zones are the stratigraphically youngest manifestations of regional-scale tectonic deformation on Venus. Rifts are spatially and temporarily associated with the youngest lava flows and often cut the crest areas of large, but isolated, dome-shaped rises. Structures of rift zones always cut the surface of the vast plains, which means that rifts are separated in time from the ancient tectonic regime, post-date the regional plains, and represent a new phase of tectonism that was contemporaneous with the late volcanism of lobate plains. Rift zones and lobate plains define the third, network rifting-volcanism regime, of resurfacing that was related to late stages of evolution of the dome-shaped rises.

  8. Development and evaluation of the offshore and coastal dispersion model

    SciTech Connect

    Hanna, S.R.; Schulman, L.L.; Paine, R.J.; Pleim, J.E.; Baer, M.

    1985-10-01

    The Offshore and Coastal Dispersion (OCD) model has been developed for the Minerals Management Service (MMS) to determine the impact of offshore and onshore emissions from point sources on the air quality of coastal regions. Constructed on the framework of the EPA guideline model MPTER, the OCD model incorporates overwater plume transport and dispersion as well as changes that occur as the plume crosses the shoreline. Hourly meteorological data are needed from both offshore and onshore locations, including wind direction and speed, mixing height, overwater air temperature and relative humidity, and the sea surface temperature. Observed turbulence intensities are preferred by the model but are not mandatory. Dispersion coefficients are proportional to turbulence intensities. A virtual source technique is used to change the rate of plume growth as the overwater plume intercepts the overland internal boundary layer. The continuous shoreline fumigation case is treated using an approach suggested by Deardorff and Willis. Calculation of plume reflection from elevated terrain follows the Rough Terrain Dispersion Model (RTDM). The OCD model and the modified EPA model used as an interim model for overwater applications by the MMS were tested with measurements from three offshore tracer experiments. The OCD model was shown to be a clear improvement over the EPA model and was officially approved by the MMS in March 1985.

  9. The unreasonable effectiveness of stratigraphic and geomorphic experiments

    NASA Astrophysics Data System (ADS)

    Paola, Chris; Straub, Kyle; Mohrig, David; Reinhardt, Liam

    2009-12-01

    The growth of quantitative analysis and prediction in Earth-surface science has been accompanied by growth in experimental stratigraphy and geomorphology. Experimenters have grown increasingly bold in targeting landscape elements from channel reaches up to the entire erosional networks and depositional basins, often using very small facilities. The experiments produce spatial structure and kinematics that, although imperfect, compare well with natural systems despite differences of spatial scale, time scale, material properties, and number of active processes. Experiments have been particularly useful in studying a wide range of forms of self-organized (autogenic) complexity that occur in morphodynamic systems. Autogenic dynamics creates much of the spatial structure we see in the landscape and in preserved strata, and is strongly associated with sediment storage and release. The observed consistency between experimental and field systems despite large differences in governing dimensionless numbers is what we mean by "unreasonable effectiveness". We suggest that unreasonable experimental effectiveness arises from natural scale independence. We generalize existing ideas to relate internal similarity, in which a small part of a system is similar to the larger system, to external similarity, in which a small copy of a system is similar to the larger system. We propose that internal similarity implies external similarity, though not the converse. The external similarity of landscape experiments to natural landscapes suggests that natural scale independence may be even more characteristic of morphodynamics than it is of better studied cases such as turbulence. We urge a shift in emphasis in experimental stratigraphy and geomorphology away from classical dynamical scaling and towards a quantitative understanding of the origins and limits of scale independence. Other research areas with strong growth potential in experimental surface dynamics include physical-biotic interactions, cohesive effects, stochastic processes, the interplay of structural and geomorphic self-organization, extraction of quantitative process information from landscape and stratigraphic records, and closer interaction between experimentation and theory.

  10. Louisiana continental slope: geologic and seismic stratigraphic framework

    SciTech Connect

    Ray, P.K.; Cooke, D.W.

    1987-05-01

    The continental slope of Louisiana from Green Canyon to Mississippi Canyon was studied by interpreting seismic CDP data and wells in the area. The slope is characterized by blocked canyon intraslope basins of various dimensions with maximum thickness of sediments in excess of 21,000 ft, rotational slump blocks and large-scale submarine slides. In the subsurface, the outer shelf and upper slope show contrasting character with that of the lower slope, especially below the Sigsbee Scarp. The seismic stratigraphic units established for the deep sea area can be recognized in their entirety up to a water depth of 6000 to 5500 ft. In shallower water salt tectonics obliterates the sequence. Fragmental records of the sequence, especially the top of Challenger boundary, have been recognized in as shallow as 2000 to 3000 ft of water. The Tertiary units often downlap and onlap directly on the Challenger unit, indicating the progradational nature of the clastic slope. The Sigsbee unit has been traced through the entire slope area and can be divided into five subunits of unique acoustical characteristics. The slope constantly regrades in response to Neogene sea level fluctuations. Loading of the shelf by deltaic deposition contributes to salt sill formation and flowage of salt over deep-water sediments on the slope during high sea level. Regressive sea is represented by slope failure, formation of large-scale submarine slides, filling of blocked canyon intraslope basins which show similar seismic facies to that of Orca and Pigmy basins as reported from DSDP studies, and sporadic uplifting of salt diapirs and massifs and the formation of linear transverse salt ridges.

  11. Oriskany Sandstone: regional stratigraphic relationships and production trends

    SciTech Connect

    Diecchio, R.J.; Jones, S.E.; Dennison, J.M.

    1984-01-01

    The Oriskany or Ridgeley Sandstone usually comprises the Deerpark Stage of the Lower Devonian in the Central Appalachians. The name Oriskany Sandstone (for Oriskany Falls, New York) is the preferred name for a Deerparkian sandstone in Kentucky, Maryland, New York, Ohio, Tennessee, and West Virginia. The name Ridgely Sandstone (for Ridgeley, West Virginia) is preferred in Virginia, New Jersey, and most of Pennsylvania. In New Jersey, and locally in Pennsylvania, the Ridgeley Sandstone comprises the upper portion of the Deerparkian Oriskany Group. For the sake of simplicity, the name Oriskany will be used in this report to refer to any Deerparkian sandstone. Throughout most of its extent, the Oriskany is a fossiliferous, marine quartzarenite. It is usually calcite-cemented, but is locally quartz-cemented, and is sometimes conglomeratic in its eastern facies. It has a distincitive megascopic fauna which, along with the calcite cement, trends to leach away in outcrop to produce a friable, biomoldic sandstone. In the subsurface, however, is is usually tightly cemented. The regional stratigraphic relationships of the Oriskany are illustrated in two correlation diagrams: Figure 1 approximates a line, parallel to strike, through the center of the basin from Tennessee to New York, then heading east and southeast along the outcrop belt to southeastern New York. Figure 2 shows correlations along the outcrop belt from eastern Tennessee to central Virginia. Figures 3 through 9 are maps showing the following: extent of Oriskany; thickness and lithofacies of Deerpark stage; topography of the Oriskany surface; structural provinces; Oriskany fields and pools; pre-Oriskany geology; and post-Oriskany geology. 29 references, 9 figures.

  12. Regional comparison of syn- and post-rift sequences in salt and salt-free basins offshore Brazil and Angola/Namibia, South Atlantic

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2015-04-01

    The large South Atlantic basins offshore South America and Africa record a highly variable syn- to post-breakup tectono-stratigraphic development. The present-day diversity in the structural and sedimentary architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are i) the structural configuration of each margin segment at the time of break-up, ii) the post break-up geodynamic history including tectonics and magmatism, and iii) variations in the type, quantity and distribution of sediment input to the respective margin segment. Particularly the basins around the Rio Grande Rise - Walvis Ridge volcanic complex show a pronounced tectono-stratigraphic asymmetry both along the respective continental margin and across the Atlantic. Only a few attempts exist to establish a regional tectono-stratigraphic correlation framework across the South Atlantic Ocean, mainly because of the lack of data across entire margin segments and limited resolution of basin wide geophysics. Still unresolved issues particularly concern the explanation of the basin-specific geological evolution of respective margin segments along the same continental margin, as well as the correlation of conjugate basins and margin segments across the Atlantic Ocean. In our study we present interpretations and first-pass restorations of regional 2D seismic-reflectivity data from the large basins offshore Brazil (Pelotas Basin, Santos Basin, Campos Basin, Espirito Santo Basin), and offshore Namibia and Angola (Walvis Basin, Namibe Basin, Benguela Basin, Kwanza Basin), which represent four adjacent pairs of conjugate basins on both sides of the South Atlantic. Results are used to document and compare on a basin-scale the contrasting styles of rift and post-rift settings during and after the continental breakup.

  13. Vessel movement influences offshore communications system design

    SciTech Connect

    Holcomb, S.R.; Burger, S.D.

    1996-05-27

    Communications links for the Liuhua 11-1 oil production project, offshore China, required a system that would function with vessel movement under typhoon conditions of heavy rainfall and extreme wave action. The system includes a microwave path between two floating production facilities and a satellite connection between the offshore facilities and onshore China. The system provides multiple local-area-network (LAN) linkages, and voice with fax in English and Chinese. The satellite link has a geostabilized platform offshore and a China National Offshore Oil Corp. master earth station onshore. System operations started in mid-1995. This paper reviews the design and performance of this communications network.

  14. 1991 worldwide offshore contractors and equipment directory

    SciTech Connect

    Not Available

    1991-01-01

    This book is the information source-book for the international offshore oil industry. Within this single convenient reference you'll find addresses, phone numbers, telex, fax and cable listings for more than 3,500 companies and their key personnel in the drilling, workover, construction, service/supply/manufacturers, geophysical, diving and transportation segments of the offshore industry. Along with this vital contact information, the authors include such pertinent data as rig specifications, ownership, an equipment index, a company index and a current survey of offshore production systems from Offshore Incorporating the Oilman.

  15. Low-frequency Stoneley energy for stratigraphic evaluation

    SciTech Connect

    Hlaing, K.K.; Lemoy, C.; Maret, J.P.; Kremer, Y.; Borland, W.H.; Maw, M.

    1994-07-01

    Conventional sonic measurements of shear and compressional slowness are body waves that travel within the formation and are commonly used for petrophysical analysis of a well. Low-frequency Stoneley waves travel within the well bore and are traditionally used to interpret fractures and formation permeability, usually by analyzing the energy losses and, to a lesser extent, the slowness. The authors have found that Stoneley energy has been very useful in the identification of vuggy carbonate facies linked to paleokarstic surfaces in the Upper Burman limestone reservoir of Miocene age, in the YADANA gas deposit, offshore Myanmar. One good example is seen in well YAD-1 where the carbonate reservoir has been cored, allowing precise facies and porosity type determination. Matching Stoneley energy and core description show a striking correlation between loss of energy and vuggy carbonate facies due to karstic diagenetic processes, always in relation with reefal or near reefal facies. Accordingly, facies interpretation has tentatively been done in the deeper, noncored reservoir zone, where losses of energy are important and considered as indicating karstic influence and the specific environment.

  16. Depositional model and stratigraphic architecture of rift climax Gilbert-type fan deltas (Gulf of Corinth, Greece)

    NASA Astrophysics Data System (ADS)

    Rohais, Sbastien; Eschard, Rmi; Guillocheau, Franois

    2008-10-01

    Facies, depositional model and stratigraphic architecture of Pleistocene giant Gilbert-type fan deltas are presented, based on outcrop data from the Derveni-Akrata region along the southern coast of the Gulf of Corinth, Greece. The common tripartite consisting of topset, foreset and bottomset [Gilbert, G.K., 1885. The topographic features of lake shores: Washington, D.C., United States Geol. Survey, 5th Annual Report, 69-123.] has been identified, as well as the most distal environment consisting of turbidites, and is organised in a repetitive pattern of four main systems tracts showing a clear facies and volumetric partitioning. The first systems tract (ST1) is characterised by the lack of topset beds and the development of a by-pass surface instead, thick foresets and bottomset beds, and thick well-developed turbiditic systems. This systems tract (ST1) is organised in an overall progradational pattern. The second systems tract (ST2) is characterised by a thin topset and almost no foreset equivalent. This systems tract is not always well-preserved and is organised in an overall retrograding trend with a landward shift in the position of the offlap break. The offshore is characterised by massive sandy turbidites. The third systems tract (ST3) is characterised by small-scale deltas prograding above the staked topsets of the giant Gilbert-type fan delta. Those small Gilbert-type fan deltas are generally organised in a pure progradation evolving to an aggradational-progradational pattern. In the distal setting of those small Gilbert-type fan deltas, almost no deposits are preserved on the remaining topography of the previous Gilbert-type fan delta. The fourth systems tract (ST4) is characterised by continuous vertically aggrading topsets that laterally pass into aggrading and prograding foresets. Bottomsets and distal turbiditic systems are starved. This fourth systems tract (ST4) is organised in an overall aggrading trend. These giant Gilbert-type fan deltas correspond to the Middle Group of the Corinth Rift infill and their stratigraphic development was strongly influenced by evolving rift structure. They record the migration of the depocenter from the rift shoulder to the rift axis in four main sequences from ca. 1.5 to 0.7 Ma, related to the migration of fault activity. It is worth noting that the maximum paleobathymetry was recorded during the final stage of the progradation of the Middle Group, suggesting that the rift climax was diachronous at the scale of the entire basin. The rapid (< 1 Ma) structural and sedimentological evolution, the migration of fault activity as well as the youth of the Corinth Rift, are probably exceptional factors allowing the characterisation of such diachronism.

  17. 27. Annual Offshore Technology Conference: 1995 Proceedings. Volume 4: Field drilling and development systems

    SciTech Connect

    1995-12-31

    This conference proceedings represents volume 4 of a four volume set of offshore oil and gas operation and development. This proceedings includes papers dealing with subsea flowlines and connectors; well completion practices; new technologies associated with subsea wellheads; multiphase flow pumping and flow meters; and materials testing procedures for well tubulars. It also has a section on the overall technology utilization in developing the offshore areas of Brazil and Norway.

  18. Stratigraphic controls on seawater intrusion and implications for groundwater management, Dominguez Gap area of Los Angeles, California, USA

    USGS Publications Warehouse

    Nishikawa, T.; Siade, A.J.; Reichard, E.G.; Ponti, D.J.; Canales, A.G.; Johnson, T.A.

    2009-01-01

    Groundwater pumping has led to extensive water-level declines and seawater intrusion in coastal Los Angeles, California (USA). A SUTRA-based solute-transport model was developed to test the hydraulic implications of a sequence-stratigraphic model of the Dominguez Gap area and to assess the effects of water-management scenarios. The model is two-dimensional, vertical and follows an approximate flow line extending from the Pacific Ocean through the Dominguez Gap area. Results indicate that a newly identified fault system can provide a pathway for transport of seawater and that a stratigraphic boundary located between the Bent Spring and Upper Wilmington sequences may control the vertical movement of seawater. Three 50-year water-management scenarios were considered: (1) no change in water-management practices; (2) installation of a slurry wall; and (3) raising inland water levels to 7.6 m above sea level. Scenario 3 was the most effective by reversing seawater intrusion. The effects of an instantaneous 1-m sea-level rise were also tested using water-management scenarios 1 and 3. Results from two 100-year simulations indicate that a 1-m sea-level rise may accelerate seawater intrusion for scenario 1; however, scenario 3 remains effective for controlling seawater intrusion. ?? Springer-Verlag 2009.

  19. Seismic paleoceanography and the stratigraphic signature of rapid climate changes

    NASA Astrophysics Data System (ADS)

    Berne, Serge; Sierro, Francisco Javier

    2015-04-01

    The term "seismic paleoceanography" was introduced in 2004 by R. Schneider, a former Chair of Images, during the EC-funded « Promess » project, for highlighting the importance of seismic data in paleoceanographic reconstructions during this particular project. The interest of seismic stratigraphy prior to drilling operations, such as those of the IODP, has long been recognized, and became a pre-requisite for the submission of scientific proposals. However, this kind of expedition generally relies on relatively low resolution, multi-channel seismic data where only the impact of major climate changes can be visualized. In contrast, a large proportion of the Images community, more familiar with the Marion Dufresne, mainly considers seismic data as a support for selecting the best coring sites. The large amount of shallow cores, borehole and seismic (at various frequencies) data available in the Gulf of Lions allows us to illustrate the importance of very high- and ultra high- resolution seismic data for tracking the signature of rapid climate changes. The flooding events associated to "Bond Cycles" (bundles of several Dansgaard-Oeschger cycles) during MIS 3- MIS 2, are an example of the interesting feedbacks between seismic interpretation and high-resolution paleoceanography. These events where first identified in the Gulf of Lions through the multi-proxy analysis of cores retrieved at site PRGL1-4 (Sierro et al., 2009). In return, the re-examination of seismic data allows us to identify a series of corresponding seismic bounding surfaces (characterized by toplap and onlap terminations) along the continental slope. In terms of seismic amplitudes, the seismic surface associated to the transition between Heinrich Stadial 4 and Interstadial 8 appears as the most pronounced event during the entire MIS3-MIS2, suggesting that the magnitude of the associated sea-level change was the most important of this interval. Even more subtle events, such as the Melt Water Pulse 19 ka, have a distinct seismic stratigraphic signature, in the form of a mappable transgressive parasequence. Once identified at a specific location, such distinct seismic signatures might become important guides in the selection of coring sites along margins that have not yet been cored extensively. Sierro, F. J. et al. (2009). Phase relationship between sea level and abrupt climate change." Quaternary Science Reviews 28(25-26): 2867-2881.

  20. Structural and stratigraphic evolution of the Anza rift, Kenya

    NASA Astrophysics Data System (ADS)

    Bosworth, William; Morley, Chris K.

    1994-09-01

    The Anza rift is a large, multi-phase continental rift basin that links the Lamu embayment of southern Kenya with the South Sudan rifts. Extension and deposition of syn-rift sediments are known to have commenced by the Neocomian. Aptian-Albian strata have, thus far, not been encountered during limited drilling campaigns and, in at least one well, are replaced by a significant unconformity. Widespread rifting occurred during the Cenomanian to Maastrichtian, and continued into the Early Tertiary. Marine waters appear to have reached the central Anza rift in the Cenomanian, and a second marine incursion may have occurred during the Campanian. As no wells have yet reached basement in the basinal deeps, the possibility exists that the Anza rift may have initiated in the Late Jurassic, in conjunction with extension to the south in the Lamu embayment and to the north in the Blue Nile rift of Sudan. Structural and stratigraphic evolution in the Anza rift followed a pattern that has now been inferred in several rift settings. Early phases of extension were accommodated by moderately dipping faults that produced large stratal rotations. Sedimentary environments were dominantly fluvial, with associated small lakes and dune fields. Volcanic activity is documented for the early Neocomian, but its extent is unknown. This initial style of deformation and sedimentation may have continued through several of the earliest pulses of rifting. By the Late Cretaceous, a new system of steeply dipping faults was established, that produced a deep basin without significant rotation of strata in the north, and only minor rotation in the south. This basin geometry favored the establishment of large, deep lakes, which occasionally were connected to the sea. The older basins were partly cannibalized during the sedimentary in-filling of these successor basins. Early Senonian volcanism was encountered in one well, and reflection seismic evidence suggests that one or more thick, regionally extensive igneous sills were intruded, probably during the Early Tertiary. The change in rift style from early, strongly rotational, shallow basins to late, non-rotational, deep basins has been observed in the southern Gulf of Suez/northern Red Sea, the Southwestern Turkana/northern Kenyan rift, and at Anza. It therefore takes place in rifts in variable tectonic settings, with a wide range of volcanic activity and, presumably, with different driving mechanisms. The shift in deposition in each case is away from early rift-bounding faults toward the half-graben flexural margins, further in-board to the upper structural plate. This suggests at least some component of regional simple shear in the deformation history of the rifted lithosphere, either via broad shear zones or at discrete detachment surfaces.

  1. Seismic assessment for offshore pipelines

    SciTech Connect

    Bruschi, R.; Gudmestad, O.T.; Blaker, F.; Nadim, F.

    1995-12-31

    An international consensus on seismic design criteria for onshore pipelines has been established during the last thirty years. The need to assess seismic design for offshore pipelines has not been similarly recognized. In this paper, the geotechnical hazard for a pipeline routed across steep slopes and irregular terrains affected by earthquakes, is discussed. The integrity of both natural and artificial load bearing supports is assessed.d The response of the pipeline to direct excitation from soil or through discontinuous, sparsely distributed natural or artificial supports, is commented.

  2. Offshore drilling and production structure

    SciTech Connect

    Crockett, R.K.; Palmer, H.E.; Stenning, D.G.

    1982-02-09

    The invention relates to an off-shore marine structure that provides an elevated support for a drilling and/or production platform. A structure comprised of three interlocking components is provided, the first component being a large foundation base installed on the sea bed; the second being a conical shaped support component which is engagable with the foundation base and which, releasably carries the third platform supporting component. In the preferred form, the platform supporting component comprises a centrally-disposed vertical column, means being provided to facilitate engagement of the column with the platform and the second component and to subsequently elevate the platform to an operating height above sea level.

  3. The proceedings of the special offshore symposium China

    SciTech Connect

    Li, Y.C.; Chung, J.S.

    1993-12-31

    This conference proceedings deals with the development and reservoir engineering aspects of China`s offshore oil and gas deposits. It contains papers which discuss platform design and safety engineering; platform and pipeline construction materials and testing methods; wave forces and fluid-structure interactions; computer programs for simulation and modeling of water waves resulting from both typhoons and tsunamis; and drilling equipment and techniques. This conference contains approximately 68 papers which have been individually indexed and abstracted into the electronic data base.

  4. Domestic Options to Offshore Oil and Gas.

    ERIC Educational Resources Information Center

    Kash, Don E.

    1983-01-01

    The continuing controversey over offshore oil/gas has given impetus to searching for domestic energy alternatives. The need for and types of several alternative sources are discussed. Indicates that the United States needs to pursue both offshore and other domestic liquid-fuel sources if it is to avoid becoming increasingly dependent on imports.

  5. Domestic Options to Offshore Oil and Gas.

    ERIC Educational Resources Information Center

    Kash, Don E.

    1983-01-01

    The continuing controversey over offshore oil/gas has given impetus to searching for domestic energy alternatives. The need for and types of several alternative sources are discussed. Indicates that the United States needs to pursue both offshore and other domestic liquid-fuel sources if it is to avoid becoming increasingly dependent on imports.…

  6. 1986 Offshore Contractors and Equipment Directory

    SciTech Connect

    Not Available

    1986-01-01

    The 1986 Offshore Contractors and Equipment Directory contains 3,000 listings of companies in the offshore drilling, construction, geophysical, diving, service/supply/manufacturing and transportation industries. Complete information about each business is given, including its affiliates, subsidiaries, divisions and branch offices as well as the correct address, phone, cable and telex numbers and the names of key personnel.

  7. U.S. Offshore Wind Port Readiness

    SciTech Connect

    C. Elkinton, A. Blatiak, H. Ameen

    2013-10-13

    This study will aid decision-makers in making informed decisions regarding the choice of ports for specific offshore projects, and the types of investments that would be required to make individual port facilities suitable to serve offshore wind manufacturing, installation and/or operations.

  8. Implications of Stratigraphic and Structural Data from the Bitter Spring Region, Southern Nevada

    NASA Astrophysics Data System (ADS)

    Donatelle, A.; Goeden, J.; Hannon, M.; Hickson, T.; Holter, S.; Johnson, T.; Lamb, M.; Lindberg, J.

    2004-05-01

    Deposition of the Tertiary Horse Spring Formation (HSF) in southern Nevada has been used to infer varying styles of extensional and strike-slip basin formation. Beard (1996) proposes an initial large contiguous basin of Rainbow Gardens age (ca. 26-18 Ma) that is subsequently broken up into sub-basins during Thumb time (16-14 Ma). A key locality to test this hypothesis is near the southern end of East and West Longwell Ridges, on the Bitter Spring USGS 1:24000 quadrangle (BSQ). However, the stratigraphic framework in this area is poorly defined. The BSQ is located west of the Overton arm of Lake Mead near the junction of the Las Vegas Valley Shear Zone and the Lake Mead Fault System. By mapping a portion of the quadrangle at 1:5000 scale, measuring detailed sections, and collecting ash samples from key localities, we investigated the structural and sedimentary framework of the area and have begun to clarify the stratigraphic relationships between members of the HSF. Faults fall into three categories: one set strikes north and dips moderately to the west; another strikes east-northeast and dips shallowly to the northwest; and the last strikes north and dips to the east. Many of these faults show an oblique sense of movement and may be related to movement on the White Basin (WBF) and Rodgers Spring Faults (Bohannon, 1983). A distinctive resistant limestone caps gypsiferous and clastic units on both sides of the north-south trending WBF. To the west of the WBF, this limestone is mapped as the Bitter Ridge Limestone Member of the HSF, whereas to the east it is mapped as the Thumb Member by Beard (unpub) and as the Rainbow Gardens Member by Bohannon (1983). We suspect that these limestones may be correlative; geochemical and petrographic fingerprinting of numerous ashes from our sections should allow correlation of these units across the WBF. In addition, sections from the east side of the WBF spaced over 1.5 km show conglomerate at the base, overlain by a sequence of red sandstone, gypsum, and carbonates (mainly oncolitic and peloidal limestone). These units show rapid lateral facies changes and thickness variation suggesting comparable changes in accommodation-space creation, possibly related to extensionally-induced subsidence. Paleocurrent data from the central portion of the mapping area indicate that flow was east- to southeast-directed, indicating that West Longwell Ridge may have been a topographic high during Thumb time. This interpretation is further supported by stratigraphic relationships near the basin margin, where conglomerate was deposited in buttress contact against Paleozoic limestones at the southern end of the ridge. Future work in this area includes continued mapping, Ar-Ar dating of ash mineral phases, and provenance analysis of sedimentary units.

  9. Radiocarbon analyses from Cincinnati, Ohio, and their implications for glacial stratigraphic interpretations

    USGS Publications Warehouse

    Lowell, T.V.; Savage, K.M.; Scott, Brockman C.; Stuckenrath, R.

    1990-01-01

    Detailed analysis of a site near Cincinnati, Ohio, shows that 14C ages of samples in a single geologic unit can have a range of several thousand years and ages from different stratigraphic units can overlap. At the Sharonville site, four 14C samples from organic silt below glaciogenic deposits have an inverted chronologic sequence, suggesting contamination, but nevertheless they indicate the silt was deposited before 27,000 yr B.P. A stump cluster in growth position, wood fragments, and moss from the upper surface of the silt may differ by as much as 2300 14C yr. Five ages from the stump cluster constrain the timing of a glacier advance of the Laurentide ice sheet to its southern limit in the Cincinnati area at 19,670 ?? 68 yr B.P. Overlying glaciogenic sediments contain transported wood that may be as much as 3200 yr older than the advance. This range of ages points out that, for a given site, several age measurements are required to determine when a glacier advance occurred. Because the measured ages in this study span the entire interval suggested for a twofold sequence of advance, retreat, and readvance of the margin of the Miami sublobe, we suggest a single advance to its terminal position in the Cincinnati area as an alternate hypothesis for testing. ?? 1990.

  10. Making up for Lost Time: Stratigraphic and Geochemical Implications of a Long-Lived Sturtian Glaciation

    NASA Astrophysics Data System (ADS)

    Macdonald, F. A.; Schmitz, M. D.; Condon, D. J.; Zhu, M.; Rooney, A. D.; Brandon, A. D.

    2014-12-01

    Geochronology provides a direct test of many models pertaining to the nature of Cryogenian climate change. Here we present new U-Pb and Re-Os geochronological constraints on Sturtian glacial deposits from Zambia, Arctic Alaska, Mongolia, South China, and throughout Laurentia. We present these new ages in stratigraphic, sedimentological and geochemical context to integrate data from other key localities, such as Namibia and Australia, and to construct a new age model for the Cryogenian Period. We find that there is no evidence for a global, pre-717 Ma glaciation. Instead, Sturtian glacial deposits appeared on all of these cratons by 717 Ma following widespread basaltic volcanism. We then review the nature and duration of the >50 Myr long Sturtian glacial epoch. In many localities, strata deposited during this interval are characterized by two massive diamictite units separated by diamictite-free, siliciclastic strata. These intervening clast-poor deposits are commonly interpreted to represent an interglacial period, however, alternatively they formed during a long-lived glaciation as newly rifted margins subsided and detached from the ice-grounding line. In the aftermath of the Sturtian glaciation, high sedimentation rates made up for lost time, and filled pent-up accommodation space, creating thick Cryogenian non-glacial interlude deposits on many margins. We discuss implications for geochemical cycles and the interpretation of carbon isotope anomalies.

  11. Hydrodynamic trapping in the Cretaceous Nahr Umr lower sand of the North Area, Offshore Qatar

    SciTech Connect

    Wells, P.R.A.

    1988-03-01

    A hydrodynamic model is described to account for oil and gas occurrences in the Cretaceous of offshore Qatar, in the Arabian Gulf. Variable and inconsistent fluid levels and variable formation water potentials and salinities cannot be explained by combinations of stratigraphic and structural trapping. Indeed, there is no structural closure to the southwest of the oil and gas accumulations. The water-potential and salinity data and oil distribution are consistent with this model and indicate that a vigorous hydrodynamic system pervades the Cretaceous of the Arabian Gulf region. Extensive upward cross-formational discharge is taking place in the North Area. This cross-formation water flow could be partly responsible for localized leaching and reservoir enhancement in the chalky limestones.

  12. Development of fast wireless detection system for fixed offshore platform

    NASA Astrophysics Data System (ADS)

    Li, Zhigang; Yu, Yan; Jiao, Dong; Wang, Jie; Li, Zhirui; Ou, Jinping

    2011-04-01

    Offshore platforms' security is concerned since in 1950s and 1960s, and in the early 1980s some important specifications and standards are built, and all these provide technical basis of fixed platform design, construction, installation and evaluation. With the condition that more and more platforms are in serving over age, the research about the evaluation and detection technology of offshore platform has been a hotspot, especially underwater detection, and assessment method based on the finite element calculation. For fixed platform structure detection, conventional NDT methods, such as eddy current, magnetic powder, permeate, X-ray and ultrasonic, etc, are generally used. These techniques are more mature, intuitive, but underwater detection needs underwater robot, the necessary supporting tools of auxiliary equipment, and trained professional team, thus resources and cost used are considerable, installation time of test equipment is long. This project presents a new kind of fast wireless detection and damage diagnosis system for fixed offshore platform using wireless sensor networks, that is, wireless sensor nodes can be put quickly on the offshore platform, detect offshore platform structure global status by wireless communication, and then make diagnosis. This system is operated simply, suitable for offshore platform integrity states rapid assessment. The designed system consists in intelligence acquisition equipment and 8 wireless collection nodes, the whole system has 64 collection channels, namely every wireless collection node has eight 16-bit accuracy of A/D channels. Wireless collection node, integrated with vibration sensing unit, embedded low-power micro-processing unit, wireless transceiver unit, large-capacity power unit, and GPS time synchronization unit, can finish the functions such as vibration data collection, initial analysis, data storage, data wireless transmission. Intelligence acquisition equipment, integrated with high-performance computation unit, wireless transceiver unit, mobile power unit and embedded data analysis software, can totally control multi-wireless collection nodes, receive and analyze data, parameter identification. Data is transmitted at the 2.4GHz wireless communication channel, every sensing data channel in charge of data transmission is in a stable frequency band, control channel responsible for the control of power parameters is in a public frequency band. The test is initially conducted for the designed system, experimental results show that the system has good application prospects and practical value with fast arrangement, high sampling rate, high resolution, capacity of low frequency detection.

  13. Stratigraphic and structural characteristics of the Romanian Black Sea shelf

    NASA Astrophysics Data System (ADS)

    Dinu, C.; Wong, H. K.; Tambrea, D.; Matenco, L.

    2005-12-01

    The Western Black Sea basin opened during Cretaceous times by back-arc rifting in association with a north dipping subduction at the rear of the Cretaceous-Early Tertiary Pontide volcanic arc. The sedimentary wedge developed on the shelf of the Romanian Black Sea sector reflects a complex interplay between large scale rifting, uplift of the orogenic flanks, large-scale post-rift subsidence and sea level changes. We examine the detailed structural configuration of this sector for a regional correlation with the adjacent offshore in Ukraine and Bulgaria. The evolution of the western Black Sea basin started in the Albian-Cenomanian times, when two extensional phases with significantly different directions (N-S and subsequently E-W) lead to the formation of a complex interplay between isolated blocks organised in horsts and grabens generally deepening eastwards. Superposition of normal faults footwall blocks from the two extensional episodes generated a deeply subsided area with enhanced accommodation space, i.e., the Histria Depression, and, consequently, recorded a larger thickness of Paleogene sediments in the post-rift stage. (Re)activation of faults and associated folding reflects repeated inversion during the Late Cretaceous-Oligocene times, associated with subsequent periods of non-deposition and/or erosion during moments of basin fill exposure. These periods of inversion recorded in the Black Sea are controlled by coeval orogenic deformations taking place in the Balkans, Pontides and the Crimean thrust belt. Sea level fluctuations during the Neogene and late Alpine tectonics in the neighbouring orogens caused massive sedimentation followed by sediment starvation and/or significant erosion. Large thicknesses of sediments accumulated during the Pontian, presumably associated with an extensional episode deepening the distal parts of the basin and with differential compaction structures. The interpretation of a high-quality seismic dataset combined with published data allowed the correlation of major structural units and lineaments defined onshore towards the Carpathians with the ones deeply buried below the western Black Sea basin sediments. Unit correlations are furthermore used to derive an integrated tectonic image of the western Black Sea area.

  14. The International Subcommission on Stratigraphic Classification of the International Commission on Stratigraphy: The Knowledge

    NASA Astrophysics Data System (ADS)

    Pratt, Brian

    2014-05-01

    The International Subcommission on Stratigraphic Classification (ISSC) was born in 1955 as an effort to promote awareness of stratigraphic principles and encourage worldwide standardization of stratigraphic approaches and terminology. The first major achievement of ISSC was the 1976 publication of the International Stratigraphic Guide. It was revised in 1994, with an abridged version appearing in 1999. These documents achieved their goals magnificently: cited innumerable times and forming the core of many national stratigraphic codes. As the discipline has evolved, particularly from technological advances and ocean drilling, new tools and methodologies have been developed and these have led to ever finer resolution of geological time and ever more exact correlation of stratigraphic units and events, thereby enhancing the understanding of the genesis of the geological record. Under the leadership of M. B. Cita, ISSC embarked in 2002 on a renewed initiative to disseminate to the global geological community these newer developments, and ultimately incorporate them into a third edition of the Guide. To this aim, traditional and new branches of stratigraphy are being treated: chemostratigraphy, cyclostratigraphy, magnetostratigraphy, lithostratigraphy, sequence stratigraphy, biostratigraphy, and chronostratigraphy. An open-access review paper is dedicated to each and published in Newsletters on Stratigraphy. The next edition of the Guide will be inclusive of all branches of stratigraphy and also embrace igneous and metamorphic rocks. It is envisaged that a textbook on stratigraphy based on these papers and the revised Guide could prove a timely contribution, especially to younger generations of practitioners, and aid global communication and understanding of stratigraphic principles and methods.

  15. Tephrochronology offshore Ischia Island, Tyrrhenian sea, Italy

    NASA Astrophysics Data System (ADS)

    Insinga, Donatella; Sulpizio, Roberto; de Alteriis, Giovanni; Morabito, Simona; Morra, Vincenzo; Sprovieri, Mario; di Benedetto, Claudia; Lubritto, Carmine; Zanchetta, Giovanni

    2010-05-01

    This work presents the analytical results of a tephrochronological study carried out on 12 gravity cores collected offshore southern Ischia island down to a maximum depth of 1238 m. The more distal site (core C1071) is located few kilometers to the west of the "Banco delle Sirene" seamount, not far from the Magnaghi and Dohrn canyons. The composite succession records at least the last ca. 40 kyrs of marine sedimentation as deduced by 14C AMS dating and tephrostratigraphy. This is consistent with the attribution, on the basis of the calcareous nannofossil assemblages, to the Emiliania huxleyi Acme Zone (Rio et al., 1990) in the latest Pleistocene-Holocene time interval. Eight primary tephra layers were recognised and analysed. They are generally represented by coarse to fine ash alternating with a number of volcaniclastic turbidites along the whole succession. The glass fraction was geochemically characterised through SEM-EDS analyses and shows clear affinities with products erupted during significant explosive events occurred in the Campania Plain, Ischia and Procida islands during the last 40 kyrs. Four ash layers were correlated with several eruptions occurred on Ischia island between the Middle Ages and Roman times and at ~ cal. 17 ka B.P. Deposits related to explosive activity occurred on Procida island were also found and dated at ~23 cal ka. Among the most ancient tephra layers, the best preserved horizon, 30 cm thick, is represented by the flegrean products of the Campanian Ignimbrite event (39 ka; De Vivo et al., 2001) the marine signature of which is known as C13 tephra in the Tyrrhenian (Thon-That et al., 2001). The peculiar composition and stratigraphic position of two other main marker tephras recognised in the succession, allowed us to correlate them with the still poorly known Schiava (36 ka B.P.; Paterne and Guichard, 1993; Sulpizio et al., 2003) and Codola (~33. cal ka B.P.; this work) fall-out products which occur as 7-5 cm-thick pumice layers at the coring site. The definition of the source area of these two major events is still a matter of debate. However, the Somma-Vesuvius complex reasonably sourced the Schiava deposits while a Campi Flegrei provenance for the Codola deposits cannot be ruled out (Di Vito et al., 2008). These latters, known as C10 tephra in the Tyrrhenian and Adriatic sea (Paterne et al., 1988; Giaccio et al., 2008), in particular, represent reliable regional markers for the whole central Mediterranean area. References De Vivo, B., Rolandi, G., Gans, P.B., Calvert, A., Bohrson,W.A., Spera, F.J., Belkin, H.E., 2001. New constraints on the pyroclastic eruptive history of the Campanian volcanic Plain (Italy). Mineralogy and Petrology 73, 47-65. Di Vito,M.A., Sulpizio, R., Zanchetta, G., D'Orazio, M., 2008. The late Pleistocene pyroclastic deposits of the Campanian Plain: newinsights into the explosive activity of Neapolitan volcanoes. J. Volcanol. Geotherm. Res.177, 19-48. Giaccio, B., Isaia, R., Fedele, F.G., Di Canzio, E., Hoffecker, J., Ronchitelli, A., Sinitsyn, A., Anikovich, M., Lisitsyn, S.N., 2008. The Campanian Ignimbrite and Codola tephra layers: two temporal/stratigraphic markers for the Early Upper Palaeloithic in southern Italy and eastern Europe. J. Volcanol. Geotherm. Res. 177, 210-228. Paterne M., Guichard F. & Labeyrie J., 1988. Explosive activity of the south Italian volcanoes during the past 80.000 years as determined by marine tephrochronology. J. Volcanol. Geother. Res. 34, 153-172. Paterne, M., Guichard, F., 1993. Triggering of volcanic pluses in the Campanian area, south Italy, by periodic deep magma in.ux. Journal of Geophysical Research 98 (B2), 1861-1873. Rio, D., Raffi, I., Villa, G., 1990. Pliocene-Pleistocene calcareous nannofossil distribution patterns in the western Mediterranean. In: Kastens, K.A. (Ed.), Proceedings of the Ocean Drilling Program. Scientific Results, vol. 107. Ocean Drilling Program, College Station, TX, pp. 513-533. Sulpizio, R., Zanchetta, G., Paterne, M., Siani, G., 2003. A review of tephrostratigraphy in central and southern Italy during the last 65 ka. Il Quaternario 16, 91-108. Ton-That, T., Singer, B., Paterne, M., 2001. 40Ar/39Ar dating of latest Pleistocene (41 ka) marine tephra in the Mediterranean Sea: implications for global climate records.Earth and Planetary Science Letters 184, 645-658.

  16. Petroleum geology of the deltaic sequence, Rio Del Rey basin, offshore Cameroon

    SciTech Connect

    Coughlin, R.M.; Bement, W.O.; Maloney, W.V. )

    1993-09-01

    The Rio Del Rey Basin of offshore Cameroon comprises the easternmost portion of the Niger delta complex. In the delta flank setting, the overall package is thinner and stratigraphic correlation simpler than in the depocenter to the west so the distribution of reservoirs and seals is well defined. Productive reservoirs are shallow, typically less than 2000 m, and mostly hydropressured to slightly overpressured. Reservoir properties generally are excellent and seismic bright-spot technology has played a major role in exploration and development efforts. Rio Del Rey is characterized by three main structural styles from north to south: (1) detachment-based growth faults, (2) highly faulted, mobile shale cored domes and ridges, and (3) toe thrusts and folds. Virtually all individual traps are fault dependent and lack of sufficient internal seals in sand-rich wave-dominated deltaic sequences can limit the objective window. Most fields are downthrown fault traps in which hanging-wall reservoirs are effectively sealed against older prodelta and marine shales. All large oil fields are located in the dome and ridge province and are potential analogs for similar structures now being explored on the upper slope off Nigeria. The best quality source rocks identified thus far are Paleocene to Eocene marine shales. Oil vs. gas distribution in the basin is a function of variations in the kerogen type, organic richness, and maturity of these source rocks. A significant quantity of the gas found to date in Rio Del Rey is biogenic in origin. The Cameroon charge model may aid in better understanding hydrocarbon distribution on offshore Nigeria, where the Miocene deltaic section is much thicker and potential Paleocene-Eocene source rocks likely are unpenetrated. The shallow deltaic play in Cameroon is relatively mature. Future exploration likely will focus on identifying deeper, nonbright-spot-supported opportunities including potential stratigraphic traps.

  17. Experimental study on moonpool resonance of offshore floating structure

    NASA Astrophysics Data System (ADS)

    Yang, Seung-Ho; Kwon, Sun-Hong

    2013-06-01

    Offshore floating structures have so-called moonpool in the centre area for the purpose of drilling, installation of subsea structures, recovery of Remotely-Operated Vehicle (ROV) and divers. However, this vertical opening has an effect on the operating performance of floating offshore structure in the vicinity of moonpool resonance frequency; piston mode and sloshing mode. Experimental study based on model test was carried out. Moonpool resonance of floating offshore structure on fixed condition and motion free condition were investigated. And, the effect of cofferdam which is representative inner structure inside moonpool was examined. Model test results showed that Molin's theoretical formula can predict moonpool resonance on fixed condition quite accurately. However, motion free condition has higher resonance frequency when it is compared with that of motion fixed. The installation of cofferdam moves resonance frequency to higher region and also generates secondary resonance at lower frequency. Furthermore, it was found that cofferdam was the cause of generating waves in the longitudinal direction when the vessel was in beam sea.

  18. The Marlin and Albacora giant fields, Campos Basin, offshore Brazil

    SciTech Connect

    De Souza, J.M.; Scarton, J.C.; Candido, A.; Cora, C.A.G. )

    1990-09-01

    The Albacore and Marlim giant fields are located in the province of Campos basin, about 110 km (68 mi) offshore Cape Sao Tome, in water depths ranging from 200 m (656 ft) to 2,000 m (6562 ft). The Albacora field was discovered in September 1984 by the wildcat 1-RJS-297, drilled in 293 m (961 ft) of water. Subsequently, the wildcats 1-RJS-305 and 1-RJS-342 extended the field limits to deeper waters. The Albacora field is approximately 235 km{sup 2} (90 mi{sup 2}) in area, with an estimated volume of 4.5 billion bbl of oil in place. The Marlim field was discovered in February 1985 by the wildcat 1-RJS-219A, in a water depth of 853 m (2,800 ft). The Marlim field area is about 152 km{sup 2} (58 mi{sup 2}), and the latest estimate of oil in place is about 8.2 billion bbl. The Marlim complex encompasses Marlim field itself and the surrounding proved and potential areas known as East-of-, West-of-, and South-of-Marlim, respectively. The current estimated volume of oil in place in the Marlim complex is close to 13.9 billion bbl, with a total surface of about 350 km{sup 2} (135 mi{sup 2}). Oil production in the Albacora field comes from Lower Cretaceous (Albian) and Tertiary (Eocene, Oligocene, and Miocene) turbidite reservoirs. Oligocene turbidite sandstones are the potential reservoirs in the Marlim field. These deposits are genetically associated with sea level variations and are mainly composed of massive sandstones and, subordinately, of contourites. Both fields are structurally and stratigraphically controlled accumulations. Hydrocarbons are trapped in anticlines and/or faulted blocks associated with salt tectonics. Stratigraphic contributions result from sandstone bodies pinching out against shales and marls. The development of these fields has been supported by three-dimensional seismic data. The Albacora field is being gradually put on stream from shallower to deeper waters.

  19. Offshore Wind Energy Systems Engineering Curriculum Development

    SciTech Connect

    McGowan, Jon G.; Manwell, James F.; Lackner, Matthew A.

    2012-12-31

    Utility-scale electricity produced from offshore wind farms has the potential to contribute significantly to the energy production of the United States. In order for the U.S. to rapidly develop these abundant resources, knowledgeable scientists and engineers with sound understanding of offshore wind energy systems are critical. This report summarizes the development of an upper-level engineering course in "Offshore Wind Energy Systems Engineering." This course is designed to provide students with a comprehensive knowledge of both the technical challenges of offshore wind energy and the practical regulatory, permitting, and planning aspects of developing offshore wind farms in the U.S. This course was offered on a pilot basis in 2011 at the University of Massachusetts and the National Renewable Energy Laboratory (NREL), TU Delft, and GL Garrad Hassan have reviewed its content. As summarized in this report, the course consists of 17 separate topic areas emphasizing appropriate engineering fundamentals as well as development, planning, and regulatory issues. In addition to the course summary, the report gives the details of a public Internet site where references and related course material can be obtained. This course will fill a pressing need for the education and training of the U.S. workforce in this critically important area. Fundamentally, this course will be unique due to two attributes: an emphasis on the engineering and technical aspects of offshore wind energy systems, and a focus on offshore wind energy issues specific to the United States.

  20. Image processing in offshore engineering

    SciTech Connect

    Rodriguez, M.V.R.; A. Oliveira, M. de; Almeida, M.E.T. de; Lorenzoni, C.; Ferrante, A.J.

    1995-12-31

    The technological progress which has taken place during the last decade introduced a totally new outlook regarding the professional computational environment in general, and regarding the engineering profession in particular. During many years engineering computing was performed based on large computer centers, getting bigger and bigger all the time, going from mainframes to super computers, essentially producing numerical results on paper media. Lately, however, it has been realized that a much more productive computational environment can be implemented using an open architecture of client/server type, based on smaller lower cost equipment including workstations and PC`s, and considering engineering information in a broader sense. This papers reports briefly the experience of the Production Department of Petrobras in transforming its centralized, mainframe based, computational environment into a open distributed client/server computational environment, focusing on the problem of handling technical graphics information regarding its more than 70 fixed offshore platforms.

  1. The offshore petroleum industry: The formative years, 1945-1962

    NASA Astrophysics Data System (ADS)

    Kreidler, Tai Deckner

    1997-12-01

    This dissertation is the first to examine the offshore oil industry that was born in the calm waters of the Gulf of Mexico. It describes the industry's origins and tracks its development as a consequence of a search for new oil frontiers. In addition, it elaborates how the oil industry moved into the marine province using available technology, and was driven by the economic urgency to compete and develop new territories. Enterprising drilling contractors and operators seized the offshore gamble, finding it possible to lower the economic and technological threshold by drawing directly from wartime research and surplus equipment. Though large oil companies had placed its indelible stamp upon the industry, the smaller, independent oil operators set the pace of early offshore development. As a technological frontier, offshore development depended upon creative and unconventional engineering. Unfamiliar marine conditions tested the imagination of oil industry engineering. The unorthodox methods of John Hayward of Barnsdall Oil and R. G. LeTourneau of LeTourneau, Inc. among others transformed the industry by blending petroleum and marine engineering. Grappling with alien marine conditions and lacking formal training, Hayward and LeTourneau merged a century of practical oil field knowledge and petroleum engineering with 2,000 years of shipbuilding experience. The Gulf of Mexico served as a fertile and protective environment for the development of a fledgling industry. With calm waters, lacking the tempestuous and stormy character of the Atlantic Ocean, with a gradual sea-floor slope and saturated with the highly productive salt dome reservoirs, the Gulf became the birth place of the modern offshore oil industry. Within its protective sphere, companies experimented and developed various technical and business adaptations. Operators used technology and business strategies that increased the opportunity for success. In addition, regional academic research institutes arose as a response to increasing work done for the offshore industry. Academic areas that developed included oceanography, physical oceanography, marine biology, marine geology, meteorology, and weather forecasting, During the formative era that ended in the late 1950s the industry had formed its technological and economic foundation in the Gulf, and stood poised to seize the initiative in the North Sea, the Middle East, the Far East, and Indonesia.

  2. Worldwide offshore contractors and equipment directory, 1986

    SciTech Connect

    Not Available

    1986-01-01

    This book provides nearly 3,000 listings of companies and personnel in the drilling, construction, geophysical, diving, service/supply/manufacturinig, and transportation industries. Complete information includes addresses, phone numbers, telex and cable, and the names of key personnel in the offshore marketplace. Naval architecture, marine engineering, offshore pipelaying, design and fabrication of platforms, mobile drilling units and other offshore oil structures are included among the many other services and products presented in this directory. A completely revised and greatly expanded service/supply/manufacturing section provides much more extensive information on backup suppliers, price and delivery. Locations and personnel of thousands of branch offices and outlets are compiled.

  3. 1987 worldwide offshore contractor and equipment directory

    SciTech Connect

    Not Available

    1987-01-01

    Within this reference source there are nearly 3,000 listings of companies and personnel in the drilling, construction, geophysical, diving, service/supply/manufacturing, and transportation industries. Complete and updated information includes addresses, phone numbers, telex and cable, and the names of key personnel in the offshore marketplace. In addition, the directory supplies a company index, the 1986 Marine Transportation Survey from Offshore Magazine, the current Worldwide Survey of Offshore Production Systems from the same publication, and the new, complete Mobile Rig Survey prepared by Electronic Rig Stats.

  4. Offshore drilling to increase in 1984

    SciTech Connect

    Not Available

    1984-05-01

    A mid-year report presents a worldwide overview of offshore drilling operations. The Gulf of Mexico and the North Sea are posting substantial gains as companies rush to drill the millions of acres acquired in those sectors both last year and in previous offerings. The Middle East, Latin America and the Asia/Pacific offshore theaters will see only slight increases. The Mediterranean and African regions are expected to sustain declines. A region-by-region summary of the 1984 offshore forecast is presented showing exploration and appraisal activities, as well as development for all of these areas.

  5. Preliminary stratigraphic and petrologic characterization of core samples from USW-G1, Yucca Mountain, Nevada

    SciTech Connect

    Waters, A.C.; Carroll, P.R.

    1981-11-01

    Tuffs of the Nevada Test Site are currently under investigation to determine their potential for long-term storage of radioactive waste. As part of this program, hole USW-G1 was drilled to a depth of 6000 ft below the surface, in the central part of the Yucca Mountain area, Nevada Test Site, Nevada. Petrographic study of the USW-G1 core is presented in this report and shows the tuffs (which generally were variably welded ash flows) are partly recrystallized to a variety of secondary minerals. The important alteration products are zeolites (heulandite, clinoptilolite, mordenite and analcime), smectite clays with minor interstratified illite, albite, micas, potassium feldspar, and various forms of silica. Iijima`s zeolite zones I through IV of burial metamorphism can be recognized in the core. Zeolites are first observed at about the 1300-ft depth, and the high-temperature boundary of zeolite stability in this core occurs at about 4350 ft. Analcime persists, either metastably or as a retrograde mineral, deeper in the core. The oxidation state of Fe-Ti oxide minerals, through most of the core, increases as the degree of welding decreases, but towards the bottom of the hole, reducing conditions generally prevail. Four stratigraphic units transected by the core may be potentially favorable sites for a waste repository. These four units, in order of increasing depth in the core, are (1) the lower cooling unit of the Topopah Spring Member, (2) cooling unit II of the Bullfrog Member, (3) the upper part of the Tram tuff, and (4) the Lithic-rich tuff.

  6. Offshore medicine: Medical care of employees in the offshore oil industry

    SciTech Connect

    Cox, R.A.F.

    1987-01-01

    This book is specifically designed to help the doctor who has to provide medical care for the expanding offshore oil industry. It describes the pattern of work offshore and the medical problems which it generates. The special features of offshore medical care are described along with the training of medics, the design of hospital facilities, and the provision of back-up services to cope with them. These are special chapters on diving, hygiene, and catering, dentistry, and legal aspects.

  7. Stratigraphic relations and hydrologic properties of the Paintbrush Tuff (PTn) hydrologic unit, Yucca Mountain, Nevada

    SciTech Connect

    Moyer, T.C.; Geslin, J.K.; Flint, L.E.

    1996-08-01

    Yucca Mountain is being investigated as a potential site for a high- level nuclear waste repository. The intent of this study was to clarify stratigraphic relations within the Paintbrush Tuff (PTn) unit at Yucca Mountain in order to better understand vertical and lateral variations in hydrologic properties as they relate to the lithologic character of these rocks. This report defines informal stratigraphic units within the PTn interval, demonstrates their lateral continuity in the Yucca Mountain region, describes later and vertical variations within them, and characterizes their hydrologic properties and importance to numerical flow and transport models. We present tables summarizing the depth to stratigraphic contacts in cored borehole studies, and unit descriptions and correlations in 10 measured sections.

  8. Hierarchical construction of stratigraphic elements in surface-based reservoir models

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Xu, S.; Mukerji, T.

    2013-12-01

    We present a surface-based simulation algorithm connecting stratigraphic hierarchy with surface-based reservoir models through statistical metrics. Geostatistical simulation algorithms provide tools for modeling spatial complexity and the resulting uncertainties for energy resource assessments. As a new family within a wide array of stochastic geological models, surface-based models and rule-based algorithms effectively represent stratigraphic responses to geological events in both time and space by assigning depositional and erosional surfaces with predefined geometries and rules. Recent advances in surface-based modeling focus on simulating morphological evolution of deep-water depositional systems and constraining models to available well and seismic data. However, especially in deep-water plays, scarce well data can only bring information about local stratal features rather than relatively general information such as hierarchy or organization, when these features are below seismic resolution. Without such information, surface-based models lack geological realism and may not be reliable even when conditioned to data. Our proposed surface-based simulation algorithm links stratigraphic hierarchy with surface-based reservoir modeling through spatial statistical tools. Ripley's K-function is used to quantitatively describe the stratigraphic distribution patterns of channel deposits. We also use the compensation index metric for quantifying the strength of compensational stacking in stratigraphic elements. These two metrics help us to extract information about sedimentary hierarchy and element organization from a set of experimental strata, and bridge physical tank experiments with numerical models. We utilize these two geostatistical metrics in conjunction with a surface-based simulation algorithm to 1) integrate clustering and compensational stacking patterns of channel deposits into reservoir modeling 2) make numerical models represent a stratigraphic hierarchical framework comparable to physical tank experiments 3) explore a means of imparting stochastic structures to models and improving geological realism. These models can be used to better assess subsurface spatial uncertainty.

  9. The Implications of Stratigraphic Compatibility for Character Integration among Fossil Taxa.

    PubMed

    Wagner, Peter J; Estabrook, George F

    2015-09-01

    Two characters are stratigraphically compatible if some phylogenies indicate that their combinations (state-pairs) evolved without homoplasy and in an order consistent with the fossil record. Simulations assuming independent character change indicate that we expect approximately 95% of compatible character pairs to also be stratigraphically compatible over a wide range of sampling regimes and general evolutionary models. However, two general models of rate heterogeneity elevate expected stratigraphic incompatibility: "early burst" models, where rates of change are higher among early members of a clade than among later members of that clade, and "integration" models, where the evolution of characters is correlated in some manner. Both models have important theoretical and methodological implications. Therefore, we examine 259 metazoan clades for deviations from expected stratigraphic compatibility. We do so first assuming independent change with equal rates of character change through time. We then repeat the analysis assuming independent change with separate "early" and "late" rates (with "early" = the first third of taxa in a clade), with the early and late rates chosen to maximize the probability of the observed compatibility among the early taxa and then the whole clade. We single out Cambrian trilobites as a possible "control" group because morphometric studies suggest that integration patterns are not conserved among closely related species. Even allowing for early bursts, we see excess stratigraphic incompatibility (i.e., negative deviations) in significantly more clades than expected at 0.50, 0.25, and 0.05 [Formula: see text] values. This pattern is particularly strong in chordates, echinoderms, and arthropods. However, stratigraphic compatibility among Cambrian trilobites matches the expectations of integration studies, as they (unlike post-Cambrian trilobites) do not deviate from the expectations of independent change with no early bursts. Thus, these results suggest that processes such as integration strongly affect the data that paleontologists use to study phylogeny, disparity, and rates. PMID:26140932

  10. 3D stratigraphic forward modelling of Shu'aiba Platform stratigraphy in the Bu Hasa Field, Abu Dhabi, United Arab Emirates.

    NASA Astrophysics Data System (ADS)

    Hu, J.; Lokier, S. W.

    2012-04-01

    This paper presents the results of three dimensional sequence stratigraphic forward modelling of the Aptian age Shu'aiba Formation from Abu Dhabi, United Arab Emirates (UAE). The Shu'aiba Formation lies within the uppermost part of the Lower Cretaceous Thamama Group and forms one of the most prolific hydrocarbon reservoir intervals of the Middle East with production dating back to the 1960's. The Shu'aiba Formation developed as a series of laterally-extensive shallow-water carbonate platforms in an epeiric sea that extended over the northern margin of the African-Arabian Plate. This shallow sea was bounded by the Arabian Shield to the west and the passive margin with the Neo-Tethys Ocean towards the north and east (Droste, 2010). The exposed Arabian Shield acted as a source of siliciclastic sediments to westernmost regions, however, more offshore areas were dominated by shallow-water carbonate deposition. Carbonate production was variously dominated by Lithocodium-Baccinella, orbitolinid foraminifera and rudist bivalves depending on local conditions. While there have been numerous studies of this important stratigraphic interval (for examples see van Buchem et al., 2010), there has been little attempt to simulate the sequence stratigraphic development of the formation. During the present study modelling was undertaken utilising the CARBONATE-3D stratigraphic forward modelling software (Warrlich et al., 2008; Warrlich et al., 2002)) thus allowing for the control of a diverse range of internal and external parameters on carbonate sequence development. This study focuses on platform development in the onshore Bu Hasa Field - the first giant oilfield to produce from the Shu'aiba Formation in Abu Dhabi. The carbonates of the Bu Hasa field were deposited on the southwest slope of the intra-shelf Bab Basin, siliciclastic content is minor. Initially these carbonates were algal dominated with rudist mounds becoming increasingly important over time (Alsharhan, 1987). Numerous simulations were undertaken, employing different sea level curves, platform geometries, etc. in order to accurately constrain and compare simulated facies geometries with those hypothesised from subsurface correlations. An initial low-angle ramp geometry was later overprinted by the development of localised relief through faulting and salt diapirism. Areas of bathymetric relief became sites of enhanced carbonate development with over-production resulting in aggradational geometries rapidly evolving to progradational systems. Several different regional, global and composite relative sea level curves were employed in the simulations in order to produce stratigraphic geometries comparable to those reported from previous studies. We conclude that none of the published sea level curves produce facies geometries directly analogous to those hypothesised from the sub-surface. We infer that this disparity primarily results from previous models lacking sufficient accommodation space and employing unrealistic carbonate production rates.

  11. EMS offshore. A new horizon for paramedics.

    PubMed

    Mallard, A S

    1991-10-01

    The difficulty in getting medical aid to offshore drilling platforms can be a source of life-threatening delays. Recently, some companies have charted new waters by actually stationing EMS crews on their rigs. PMID:10116023

  12. Offshore oil in the Alaskan Arctic

    NASA Technical Reports Server (NTRS)

    Weeks, W. F.; Weller, G.

    1984-01-01

    Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent natural gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occuur offshore beneath the shallow, ice-covered seas of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.

  13. Requirements for construction of offshore concrete platforms

    SciTech Connect

    Gudmestad, O.T.; Pollard, N.

    1994-12-31

    For development of offshore fields, the operator must select production concepts. As several options like subsea templates, floating production and storage concepts, semisubmersibles and steel platforms etc. are available, this paper will review the specifics of one of the possible concepts, the concrete platform. The application of offshore concrete platforms is gaining renewed interest world wide. Several operators are presently carrying out comparisons between offshore concrete structures and jacket support structures. This evaluation includes considerations related to constructability incorporating studies of potential construction sites, and infrastructures as well as availability of materials. This paper summarizes requirements for carrying out an offshore concrete platform construction project and will be useful to those interested in concrete projects.

  14. Engineering Challenges for Floating Offshore Wind Turbines

    SciTech Connect

    Butterfield, S.; Musial, W.; Jonkman, J.; Sclavounos, P.

    2007-09-01

    The major objective of this paper is to survey the technical challenges that must be overcome to develop deepwater offshore wind energy technologies and to provide a framework from which the first-order economics can be assessed.

  15. Stratigraphic Profiles for Selected Hanford Site Seismometer Stations and Other Locations

    SciTech Connect

    Last, George V.

    2014-02-01

    Stratigraphic profiles were constructed for eight selected Hanford Site seismometer stations, five Hanford Site facility reference locations, and seven regional three-component broadband seismometer stations. These profiles provide interpretations of the subsurface layers to support estimation of ground motions from past earthquakes, and the prediction of ground motions from future earthquakes. In most cases these profiles terminated at the top of the Wanapum Basalt, but at selected sites profiles were extended down to the top of the crystalline basement. The composite one-dimensional stratigraphic profiles were based primarily on previous interpretations from nearby boreholes, and in many cases the nearest deep borehole is located kilometers away.

  16. CABFAC/USGS, a FORTRAN program for Q-mode factor analysis of stratigraphically ordered samples

    USGS Publications Warehouse

    Adams, David P.

    1976-01-01

    This program is a revision of the CABFAC program of Kovan and Imbrie (1971) which incorporates the following improvements: each factor is plotted against depth on the printer; samples are ordered stratigraphically by the program, so that input data need not be ordered stratigraphically; an option has been added to transform all variables to zero means before calculating the cosine-theta matrix; and all subroutines are variable-dimensioned, so that the size of .the program may be changed by simply altering the main program.

  17. A simple high-precision Jacob's staff design for the high-resolution stratigrapher

    USGS Publications Warehouse

    Elder, W.P.

    1989-01-01

    The new generation of high-resolution stratigraphic research depends upon detailed bed-by-bed analysis to enhance regional correlation potential. The standard Jacob's staff is not an efficient and precise tool for measuring thin-bedded strata. The high-precision Jacob's staff design presented and illustrated in this paper meets the qualifications required of such an instrument. The prototype of this simple design consists of a sliding bracket that holds a Brunton-type compass at right angles to a ruled-off staff. This instrument provides rapid and accurate measurement of both thick- or thin-bedded sequences, thus decreasing field time and increasing stratigraphic precision. -Author

  18. StrataBase: A stratigraphical database and processing program for microcomputers

    NASA Astrophysics Data System (ADS)

    Ripepe, Maurizio

    Stratigraphical work focuses on changes of many parameters through sequences of strata as records of geological history. Quantitative stratigraphy therefore needs a database organized primarily by sequence and amenable to sequential forms of analysis: sequential changes in composition or compositional ratios, Markovian chains, time-series analysis of cyclicities. It also needs ready graphical conversion of numerical data in stratigraphical or statistical format. StrataBase is such a database designed for the Macintosh 512, written in Microsoft BASIC 2.0 and in Assembly language 68000. Data are filled in a bidimensional 314 K matrix, and are rendered totally accessible by a Virtual Disk in the RAM.

  19. South Marsh Island Block 128 field, offshore Louisiana

    SciTech Connect

    Lammlein, D.R.; Leedy, J.B.; Nester, D.C.; Austin, J.M.

    1989-03-01

    The South Marsh Island Block 128 field is one of the larger producing fields in the Gulf of Mexico. At peak production, this giant field ranked third in annual oil production in federal offshore continental shelf (OCS) waters. The field was discovered by the Pennzoil OCS-G-2587 No. 1 well in 1974. Production commenced in July 1977. Seventy-seven exploratory and development wells have been drilled. Cumulative production from three production platforms is over 81 million bbl of oil and 89 billion ft/sup 3/ of gas. Estimated ultimate recovery is 101 million bbl of oil and 175 billion ft/sup 3/ of gas. The field is a faulted anticline underlain by salt. Production is from 20 Pleistocene sandstones sourced by deeply buried pre-Pleistocene shales. Faulting and permeability barriers separate these sandstones into 93 complex reservoirs. Because of very favorable geologic conditions and vast improvements in seismic technology since the acquisition of Block 128, the field was selected for an integrated geological and geophysical evaluation. This study used a dense grid of modern and reprocessed 2-D and 3-D GRID/sup TM/ data for detailed seismic stratigraphic and structural mapping. Seismic and well data were integrated utilizing synthetic seismograms, seismic modeling, and petrophysical studies. Following this evaluation, two exploratory and four development wells were drilled. A fourth production platform is being fabricated to develop an extension to the field. Reserve additions from drilling and revisions have significantly increased recoverable reserves. This ongoing evaluation has continually refined their geologic understanding, and although the field is mature, exploration and development continue.

  20. Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    McMillen, K.J.; Do Van Luu; Lee, E.K.; Hong, S.S.

    1996-12-31

    An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in the tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.

  1. Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    McMillen, K.J. ); Do Van Luu; Lee, E.K.; Hong, S.S. )

    1996-01-01

    An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in the tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.

  2. Preliminary seismic characterization of parts of the island of Gotland in preparation for a potential CO2 storage test site

    NASA Astrophysics Data System (ADS)

    Lydersen, Ida; Sopher, Daniel; Juhlin, Christopher

    2015-04-01

    Geological storage of CO2 is one of the available options to reduce CO2-emissions from large point sources. Previous work in the Baltic Sea Basin has inferred a large storage potential in several stratigraphic units. The most promising of these is the Faludden sandstone, exhibiting favorable reservoir properties and forming a regional stratigraphic trap. A potential location for a pilot CO2 injection site, to explore the suitability of the Faludden reservoir is onshore Gotland, Sweden. In this study onshore and offshore data have been digitized and interpreted, along with well data, to provide a detailed characterization of the Faludden reservoir below parts of Gotland. Maps and regional seismic profiles describing the extent and top structure of the Faludden sandstone are presented. The study area covers large parts of the island of Gotland, and extends about 50-70km offshore. The seismic data presented is part of a larger dataset acquired by Oljeprospektering AB (OPAB) between 1970 and 1990. The dataset is to this date largely unpublished, therefore re-processing and interpretation of these data provide improved insight into the subsurface of the study area. Two longer seismic profiles crossing Gotland ENE-WSW have been interpreted to give a large scale, regional control of the Faludden sandstone. A relatively tight grid of land seismic following the extent of the Faludden sandstone along the eastern coast to the southernmost point has been interpreted to better understand the actual distribution and geometry of the Faludden sandstone beneath Gotland. The maps from this study help to identify the most suitable area for a potential test injection site for CO2-storage, and to further the geological understanding of the area in general.

  3. New perspectives in offshore wind energy

    PubMed Central

    Failla, Giuseppe; Arena, Felice

    2015-01-01

    The design of offshore wind turbines is one of the most fascinating challenges in renewable energy. Meeting the objective of increasing power production with reduced installation and maintenance costs requires a multi-disciplinary approach, bringing together expertise in different fields of engineering. The purpose of this theme issue is to offer a broad perspective on some crucial aspects of offshore wind turbines design, discussing the state of the art and presenting recent theoretical and experimental studies. PMID:25583869

  4. 2014 Offshore Wind Market and Economic Analysis

    SciTech Connect

    Hamilton, Bruce

    2014-08-25

    The objective of this report is to provide a comprehensive annual assessment of the U.S. offshore wind market.This 3rd annual report focuses on new developments that have occurred in 2014. The report provides stakeholders with a reliable and consistent data source addressing entry barriers and U.S. competitiveness in the offshore wind market. Available for download are both the full report and the report's underlying data.

  5. New perspectives in offshore wind energy.

    PubMed

    Failla, Giuseppe; Arena, Felice

    2015-02-28

    The design of offshore wind turbines is one of the most fascinating challenges in renewable energy. Meeting the objective of increasing power production with reduced installation and maintenance costs requires a multi-disciplinary approach, bringing together expertise in different fields of engineering. The purpose of this theme issue is to offer a broad perspective on some crucial aspects of offshore wind turbines design, discussing the state of the art and presenting recent theoretical and experimental studies. PMID:25583869

  6. Gas Production From a Cold, Stratigraphically Bounded Hydrate Deposit at the Mount Elbert Site, North Slope, Alaska

    SciTech Connect

    Moridis, G.J.; Silpngarmlert, S.; Reagan, M. T.; Collett, T.S.; Zhang, K.

    2009-09-01

    As part of an effort to identify suitable targets for a planned long-term field test, we investigate by means of numerical simulation the gas production potential from unit D, a stratigraphically bounded (Class 3) permafrost-associated hydrate occurrence penetrated in the ount Elbert well on North Slope, Alaska. This shallow, low-pressure deposit has high porosities, high intrinsic permeabilities and high hydrate saturations. It has a low temperature because of its proximity to the overlying permafrost. The simulation results indicate that vertical ells operating at a constant bottomhole pressure would produce at very low rates for a very long period. Horizontal wells increase gas production by almost two orders of magnitude, but production remains low. Sensitivity analysis indicates that the initial deposit temperature is y the far the most important factor determining production performance (and the most effective criterion for target selection) because it controls the sensible heat available to fuel dissociation.

  7. Newport-Inglewood-Carlsbad-Coronado Bank Fault System Nearshore Southern California: Testing models for Quaternary deformation

    NASA Astrophysics Data System (ADS)

    Bennett, J. T.; Sorlien, C. C.; Cormier, M.; Bauer, R. L.

    2011-12-01

    The San Andreas fault system is distributed across hundreds of kilometers in southern California. This transform system includes offshore faults along the shelf, slope and basin- comprising part of the Inner California Continental Borderland. Previously, offshore faults have been interpreted as being discontinuous and striking parallel to the coast between Long Beach and San Diego. Our recent work, based on several thousand kilometers of deep-penetration industry multi-channel seismic reflection data (MCS) as well as high resolution U.S. Geological Survey MCS, indicates that many of the offshore faults are more geometrically continuous than previously reported. Stratigraphic interpretations of MCS profiles included the ca. 1.8 Ma Top Lower Pico, which was correlated from wells located offshore Long Beach (Sorlien et. al. 2010). Based on this age constraint, four younger (Late) Quaternary unconformities are interpreted through the slope and basin. The right-lateral Newport-Inglewood fault continues offshore near Newport Beach. We map a single fault for 25 kilometers that continues to the southeast along the base of the slope. There, the Newport-Inglewood fault splits into the San Mateo-Carlsbad fault, which is mapped for 55 kilometers along the base of the slope to a sharp bend. This bend is the northern end of a right step-over of 10 kilometers to the Descanso fault and about 17 km to the Coronado Bank fault. We map these faults for 50 kilometers as they continue over the Mexican border. Both the San Mateo - Carlsbad with the Newport-Inglewood fault and the Coronado Bank with the Descanso fault are paired faults that form flower structures (positive and negative, respectively) in cross section. Preliminary kinematic models indicate ~1km of right-lateral slip since ~1.8 Ma at the north end of the step-over. We are modeling the slip on the southern segment to test our hypothesis for a kinematically continuous right-lateral fault system. We are correlating four younger Quaternary unconformities across portions of these faults to test whether the post- ~1.8 Ma deformation continues into late Quaternary. This will provide critical information for a meaningful assessment of the seismic hazards facing Newport beach through metropolitan San Diego.

  8. Reconstructing Past Depositional and Diagenetic Processes through Quantitative Stratigraphic Analysis of the Martian Sedimentary Rock Record

    NASA Astrophysics Data System (ADS)

    Stack, Kathryn M.

    High-resolution orbital and in situ observations acquired of the Martian surface during the past two decades provide the opportunity to study the rock record of Mars at an unprecedented level of detail. This dissertation consists of four studies whose common goal is to establish new standards for the quantitative analysis of visible and near-infrared data from the surface of Mars. Through the compilation of global image inventories, application of stratigraphic and sedimentologic statistical methods, and use of laboratory analogs, this dissertation provides insight into the history of past depositional and diagenetic processes on Mars. The first study presents a global inventory of stratified deposits observed in images from the High Resolution Image Science Experiment (HiRISE) camera on-board the Mars Reconnaissance Orbiter. This work uses the widespread coverage of high-resolution orbital images to make global-scale observations about the processes controlling sediment transport and deposition on Mars. The next chapter presents a study of bed thickness distributions in Martian sedimentary deposits, showing how statistical methods can be used to establish quantitative criteria for evaluating the depositional history of stratified deposits observed in orbital images. The third study tests the ability of spectral mixing models to obtain quantitative mineral abundances from near-infrared reflectance spectra of clay and sulfate mixtures in the laboratory for application to the analysis of orbital spectra of sedimentary deposits on Mars. The final study employs a statistical analysis of the size, shape, and distribution of nodules observed by the Mars Science Laboratory Curiosity rover team in the Sheepbed mudstone at Yellowknife Bay in Gale crater. This analysis is used to evaluate hypotheses for nodule formation and to gain insight into the diagenetic history of an ancient habitable environment on Mars.

  9. Arctic & Offshore Technical Data System

    Energy Science and Technology Software Center (ESTSC)

    1990-07-01

    AORIS is a computerized information system to assist the technology and planning community in the development of Arctic oil and gas resources. In general, AORIS is geographically dependent and, where possible, site specific. The main topics are sea ice, geotechnology, oceanography, meteorology, and Arctic engineering, as they relate to such offshore oil and gas activities as exploration, production, storage, and transportation. AORIS consists of a directory component that identifies 85 Arctic energy-related databases and tellsmore » how to access them; a bibliographic/management information system or bibliographic component containing over 8,000 references and abstracts on Arctic energy-related research; and a scientific and engineering information system, or data component, containing over 800 data sets, in both tabular and graphical formats, on sea ice characteristics taken from the bibliographic citations. AORIS also contains much of the so-called grey literature, i.e., data and/or locations of Arctic data collected, but never published. The three components are linked so the user may easily move from one component to another. A generic information system is provided to allow users to create their own information systems. The generic programs have the same query and updating features as AORIS, except that there is no directory component.« less

  10. Offshore oil and the coastline

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    A radical, accelerated 5-year plan to offer 875 million acres (of which 20 million could actually be leased for oil and gas extraction purposes) on the outer continental shelf (OCS) could result in the release of large volumes of drilling wastes and spillage (Environ. Sci. Tech., Nov. 1981). The actual leasing, under the 5-year plan proposed by Secretary of the Interior James G. Watt, could amount to 4-5 million acres per year—about 10 times as much, on the average, as had been leased over the past 25 years. Regulations on the environmental effects may be less complicated yet more effective in that impact statements will cover large areas instead of the tract-by-tract statements now required. A number of the new offshore leasing areas, for example, the Alaska Coast (Cook Inlet, Beaufort Bay, Gulf of Alaska), the Blake Plateau and Baltimore Canyon, and the Georges Bank, are extremely valuable in terms of renewable resources and potentially fragile in terms of environmental conditions. Fishing interests in these areas have produced considerable controversy over the planned sale of petroleum rights.

  11. Arctic & Offshore Technical Data System

    Energy Science and Technology Software Center (ESTSC)

    1990-07-01

    AORIS is a computerized information system to assist the technology and planning community in the development of Arctic oil and gas resources. In general, AORIS is geographically dependent and, where possible, site specific. The main topics are sea ice, geotechnology, oceanography, meteorology, and Arctic engineering, as they relate to such offshore oil and gas activities as exploration, production, storage, and transportation. AORIS consists of a directory component that identifies 85 Arctic energy-related databases and tellsmorehow to access them; a bibliographic/management information system or bibliographic component containing over 8,000 references and abstracts on Arctic energy-related research; and a scientific and engineering information system, or data component, containing over 800 data sets, in both tabular and graphical formats, on sea ice characteristics taken from the bibliographic citations. AORIS also contains much of the so-called grey literature, i.e., data and/or locations of Arctic data collected, but never published. The three components are linked so the user may easily move from one component to another. A generic information system is provided to allow users to create their own information systems. The generic programs have the same query and updating features as AORIS, except that there is no directory component.less

  12. The effectiveness of 3-D marine systems as an exploration tool in the offshore Niger Delta

    SciTech Connect

    Idowu, A.O. )

    1993-09-01

    From inception in 1984, three-dimensional (3-D) marine surveys have been used widely for field development where commercial hydrocarbons were known to exist in Nigeria. The high-trace density and full 3-D migration provide a data set that allows detailed interpretation of complex geologic structures and, in many cases, provides good stratigraphic information as well. The result has been better placement of development wells, making field development more efficient and cost effective. Previous application of the 3-d method (i.e., reconaissance 3-D) as an exploration tool in 1987 has demonstrated its effectiveness for predrilling detailing of prospects in offshore Niger Delta in a situation where a large volume of seismic data were acquired at relatively reduced unit costs. The technique involves acquiring data along a line every 200 m spacing, while interpretation in 3-D data processing is applied for subsequent 3-D migration. Based on pattern recognition of events on the input traces, the links are established to allow traces to be formed between input locations by comparing several attributes of events on neighboring traces. A case history example from the offshore Niger delta shows that the collection costs for the reconnaissance 3-D method are comparable to two-dimensional detailing based on similar line kilometer and time duration for the survey. A trade-off between cost and technical specifications can be programmed by focusing on the geologic objective. The technique brings the advantage of 3-D methods, but not their costs, to the exploration phase of the search for petroleum, and it is highly recommended for exploration in frontier areas, particularly the deep offshore of the Niger Delta.

  13. Inorganic geochemistry of Devonian shales in southern West Virginia: geographic and stratigraphic trends

    SciTech Connect

    Hohn, M.E.; Neal, D.W.; Renton, J.J.

    1980-04-01

    Samples of cuttings from twenty-one wells and a core from a single well in southern West Virginia were analyzed for major and minor elements: silicon, aluminum, iron, magnesium, calcium, sodium, titanium, phosphorus, manganese, sulfur, zinc, and strontium. Stratigraphic and geographic controls on elemental abundances were studied through canonical correlations, factor analyses, and trend surface analyses. The most abundant elements, silicon and aluminum, show gradual trends through the stratigraphic column of most wells, with silicon increasing and aluminum decreasing up-section. Other elements such as calcium, sulfur, and titanium change abruptly in abundance at certain stratigraphic boundaries. Important geographic trends run east-west: for instance, one can see an increase in sulfur and a decrease in titanium to the west; and a decrease in silicon from the east to the central part of the study area, then an increase further west. Although observed vertical trends in detrital minerals and geographic patterns in elemental abundances agree with the accepted view of a prograding delta complex during Late Devonian time, geographically-local, time restricted depositional processes influenced elemental percentages in subsets of the wells and the stratigraphic intervals studied. The black shales of lower Huron age do not represent simply a return of depositional conditions present in the earlier Rhinestreet time; nor do the gray shales of the Ohio Shale represent the same environmental conditions as the Big White Slate.

  14. Neoproterozoic variations in the C-isotopic composition of seawater: stratigraphic and biogeochemical implications

    NASA Technical Reports Server (NTRS)

    Kaufman, A. J.; Knoll, A. H.

    1995-01-01

    The recent proliferation of stratigraphic studies of delta 13C variation in carbonates and organic C in later Neoproterozoic and basal Cambrian successions (approximately 850-530 Ma) indicates a strong oscillating trend in the C-isotopic composition of surface seawater. Alone, this trend does not adequately characterize discrete intervals in Neoproterozoic time. However, integrated with the vectorial signals provided by fossils and Sr-isotopic variations, C isotope chemostratigraphy facilitates the interbasinal correlation of later Neoproterozoic successions. Results of these studies are evaluated in terms of four stratigraphic intervals: (1) the Precambrian/Cambrian boundary, (2) the post-Varanger terminal Proterozoic, (3) the late Cryogenian, and (4) the early Cryogenian. Where biostratigraphic or radiometric data constrain the age of Neoproterozoic sedimentary sequences, secular variations in C and Sr isotopes can provide a level of stratigraphic resolution exceeding that provided by fossils alone. Isotopic data place strong constraints on the chemical evolution of seawater, linking it to major tectonic and paleoclimatic events. They also provide a biogeochemical framework for the understanding of the initial radiation of macroscopic metazoans, which is associated stratigraphically, and perhaps causally, with a global increase in the burial of organic C and a concomitant rise of atmospheric O2.

  15. Structural and stratigraphic controls on cave development in the Oak Ridge area, Tennessee

    SciTech Connect

    Rubin, P A; Lemiszki, P J

    1992-01-01

    The Oak Ridge Reservation (ORR) is located in the northwestern part of the Valley and Ridge province in east Tennessee. The Valley and Ridge province is the topographic expression of the southern Appalachian foreland fold-thrust belt, which formed during the late Paleozoic Alleghanian orogeny. In the Oak Ridge area, three major northwest verging thrust faults (Kingston, Whiteoak Mountain, and Copper Creek) imbricate and juxtapose carbonate and clastic stratigraphic units that range in age from the lower Cambrian to the lower Mississippian. The carbonate stratigraphic units range in thickness from 1278 to 1748 m and include the Maynardville Limestone in the Conasauga Group (hereby included as part of the Knox Group), the Knox Group, and the Chickamauga Group. Stratigraphic relationships and repetition of units by thrust faulting has produced three northeast striking and southeast dipping carbonate bands bounded to the northwest and southeast by noncarbonate units. Preliminary results indicate that within two of these carbonate bands, formations composed of mudstone and argillaceous limestone appear to further subdivide groundwater basins. Our efforts have focused on relating the stratigraphic and structural characteristics of these rock units with cave development in the region.

  16. Chert horizons as time-stratigraphic markers in Ordovician and Silurian of eastern Great Basin

    SciTech Connect

    Cameron, G.J.

    1986-08-01

    Data from numerous measured sections show that distinct chert horizons occur at or near the same stratigraphic intervals in a number of Ordovician and Silurian dolomite sequences in the eastern Great basin of Nevada and Utah. In many cases a shallow-water origin for the chert is inferred because of silicified shelfal fauna and lack of deeper water indicators. The cherty intervals appear to transgress across environmentally controlled lithologic boundaries. This fact, coupled with the regional extent of the chert, suggests that these intervals can be used as time-stratigraphic marker horizons. This concept is useful in assessing the degree of stratigraphic thinning of Upper Silurian strata along a regional unconformity. Although chert is almost ubiquitously present in certain stratigraphic intervals, the abundance of chert-bearing horizons within an individual section varies. By contouring the abundance of chert-bearing intervals within the Silurian system, a well-defined pattern is documented that increases in abundance to the northeast toward the northwestern corner of Utah. The ratio of chert to dolomite within the intervals increases correspondingly. It is suggested that the chert is the result of silica supersaturation from the settling of wind-blow volcanic ash on the Silurian epicontinental sea. The distribution of the chert was largely a function of paleowind currents from an easterly or northerly active volcanic source area.

  17. Shearing along faults and stratigraphic joints controlled by land subsidence in the Valley of Queretaro, Mexico

    NASA Astrophysics Data System (ADS)

    Carreón-Freyre, D.; Cerca, M.; Ochoa-González, G.; Teatini, P.; Zuñiga, F. R.

    2016-03-01

    Slip of nearly vertical faults or horizontal stratigraphic joints has provoked the shearing of at least 16 well casings in a period of over 10 years in the Valley of Queretaro aquifer, Mexico. Evidence integrated from field observations, remote surface-deformation monitoring, in-situ monitoring, stratigraphic correlation, and numerical modeling indicate that groundwater depletion and land subsidence induce shearing. Two main factors conditioning the stress distribution and the location of sheared well casings have been identified: (1) slip on fault planes, and (2) slip on stratigraphic joints. Additionally, the distribution of piezometric gradients may be a factor that enhances shearing. Slip on faults can be generated either by the compaction of sedimentary units (passive faulting) or by slip of blocks delimited by pre-existing faults (reactivation). Major piezometric-level declines and the distribution of hydraulic gradients can also be associated with slip at stratigraphic joints. Faults and hydraulic contrasts in the heterogeneous rock sequence, along with groundwater extraction, influence the distribution of the gradients and delimit the compartments of groundwater in the aquifer. Analogue modeling allowed assessment of the distribution of stress-strain and displacements associated with the increase of the vertical stress. Fault-bounded aquifers in grabens are common in the central part of Mexico and the results obtained can be applied to other subsiding, structurally controlled aquifer systems elsewhere.

  18. Integration of the stratigraphic aspects of very large sea-floor databases using information processing

    USGS Publications Warehouse

    Jenkins, Clinton N.; Flocks, J.; Kulp, M.

    2006-01-01

    Information-processing methods are described that integrate the stratigraphic aspects of large and diverse collections of sea-floor sample data. They efficiently convert common types of sea-floor data into database and GIS (geographical information system) tables, visual core logs, stratigraphic fence diagrams and sophisticated stratigraphic statistics. The input data are held in structured documents, essentially written core logs that are particularly efficient to create from raw input datasets. Techniques are described that permit efficient construction of regional databases consisting of hundreds of cores. The sedimentological observations in each core are located by their downhole depths (metres below sea floor - mbsf) and also by a verbal term that describes the sample 'situation' - a special fraction of the sediment or position in the core. The main processing creates a separate output event for each instance of top, bottom and situation, assigning top-base mbsf values from numeric or, where possible, from word-based relative locational information such as 'core catcher' in reference to sampler device, and recovery or penetration length. The processing outputs represent the sub-bottom as a sparse matrix of over 20 sediment properties of interest, such as grain size, porosity and colour. They can be plotted in a range of core-log programs including an in-built facility that better suits the requirements of sea-floor data. Finally, a suite of stratigraphic statistics are computed, including volumetric grades, overburdens, thicknesses and degrees of layering. ?? The Geological Society of London 2006.

  19. The use of a paired comparison model in ordering stratigraphic events

    USGS Publications Warehouse

    Edwards, L.E.; Beaver, R.J.

    1978-01-01

    Data from lowest and highest occurrence events in several stratigraphic sections are analyzed by means of a paired comparison model with ties. The model produces an estimated relative geochronological ordering of these events. This ordering must be compared with actual observations for revision and interpretation. ?? 1978 Plenum Publishing Corporation.

  20. SDAR 1.0 a New Quantitative Toolkit for Analyze Stratigraphic Data

    NASA Astrophysics Data System (ADS)

    Ortiz, John; Moreno, Carlos; Cardenas, Andres; Jaramillo, Carlos

    2015-04-01

    Since the foundation of stratigraphy geoscientists have recognized that data obtained from stratigraphic columns (SC), two dimensional schemes recording descriptions of both geological and paleontological features (e.g., thickness of rock packages, grain size, fossil and lithological components, and sedimentary structures), are key elements for establishing reliable hypotheses about the distribution in space and time of rock sequences, and ancient sedimentary environmental and paleobiological dynamics. Despite the tremendous advances on the way geoscientists store, plot, and quantitatively analyze sedimentological and paleontological data (e.g., Macrostrat [http://www.macrostrat.org/], Paleobiology Database [http://www.paleodb.org/], respectively), there is still a lack of computational methodologies designed to quantitatively examine data from a highly detailed SCs. Moreover, frequently the stratigraphic information is plotted "manually" using vector graphics editors (e.g., Corel Draw, Illustrator), however, this information although store on a digital format, cannot be used readily for any quantitative analysis. Therefore, any attempt to examine the stratigraphic data in an analytical fashion necessarily takes further steps. Given these issues, we have developed the sofware 'Stratigraphic Data Analysis in R' (SDAR), which stores in a database all sedimentological, stratigraphic, and paleontological information collected from a SC, allowing users to generate high-quality graphic plots (including one or multiple features stored in the database). SDAR also encompasses quantitative analyses helping users to quantify stratigraphic information (e.g. grain size, sorting and rounding, proportion of sand/shale). Finally, given that the SDAR analysis module, has been written in the open-source high-level computer language "R graphics/statistics language" [R Development Core Team, 2014], it is already loaded with many of the crucial features required to accomplish basic and complex tasks of statistical analysis (i.e., R language provide more than hundred spatial libraries that allow users to explore various Geostatistics and spatial analysis). Consequently, SDAR allows a deeper exploration of the stratigraphic data collected in the field, it will allow the geoscientific community in the near future to develop complex analyses related with the distribution in space and time of rock sequences, such as lithofacial correlations, by a multivariate comparison between empirical SCs with quantitative lithofacial models established from modern sedimentary environments.

  1. Automated recognition of stratigraphic marker shales from geophysical logs in iron ore deposits

    NASA Astrophysics Data System (ADS)

    Silversides, Katherine; Melkumyan, Arman; Wyman, Derek; Hatherly, Peter

    2015-04-01

    The mining of stratiform ore deposits requires a means of determining the location of stratigraphic boundaries. A variety of geophysical logs may provide the required data but, in the case of banded iron formation hosted iron ore deposits in the Hamersley Ranges of Western Australia, only one geophysical log type (natural gamma) is collected for this purpose. The information from these logs is currently processed by slow manual interpretation. In this paper we present an alternative method of automatically identifying recurring stratigraphic markers in natural gamma logs from multiple drill holes. Our approach is demonstrated using natural gamma geophysical logs that contain features corresponding to the presence of stratigraphically important marker shales. The host stratigraphic sequence is highly consistent throughout the Hamersley and the marker shales can therefore be used to identify the stratigraphic location of the banded iron formation (BIF) or BIF hosted ore. The marker shales are identified using Gaussian Processes (GP) trained by either manual or active learning methods and the results are compared to the existing geological interpretation. The manual method involves the user selecting the signatures for improving the library, whereas the active learning method uses the measure of uncertainty provided by the GP to select specific examples for the user to consider for addition. The results demonstrate that both GP methods can identify a feature, but the active learning approach has several benefits over the manual method. These benefits include greater accuracy in the identified signatures, faster library building, and an objective approach for selecting signatures that includes the full range of signatures across a deposit in the library. When using the active learning method, it was found that the current manual interpretation could be replaced in 78.4% of the holes with an accuracy of 95.7%.

  2. 4-D stratigraphic architecture and 3-D reservoir zonation of the Mirado Formation, Cusiana Field, Colombia

    SciTech Connect

    Fajardo, A.A. ); Cross, T.A. )

    1996-01-01

    A high-resolution sequence stratigraphic study using 2300 feet of core calibrated with geophysical logs from 14 wells and 1800 measurements of porosity and permeability established the 4-D stratigraphy and 3-D reservoir zonation of the Mirador. Virtually all reservoir-quality facies are through cross-stratified sandstones which occur in channel facies successions in the lower Mirador, but in bay-head delta and estuarine channel facies successions in the upper Mirador. Petrophysical properties and the geometry, continuity and volume of reservoir-quality sandstones change regularly as function of their stratigraphic position. These vertical facies successions reflect increasing accommodation-to-sediment supply (A/S) ratio through each intermediate-term cycle. The upper long-term cycle comprises four intermediate-term, landward-stepping, symmetrical base-level cycles. These cycles consist of estuarine channel, bay-head to bay-fill facies successions. The transition from channel to bay-head to bay-fill facies successions represents an increase in A/S ratio, and the reverse transition indicates a decrease in A/S ratio. Sixteen reservoir zones were defined within the Cusiana field. Reservoirs within the upper and lower long-term cycles are separated by a continuous middle Mirador mudstone which creates two large reservoir divisions. At the second level of zonation, the reservoir compartments and fluid-flow retardants coincide with the intermediate-term stratigraphic cycles. A third level of reservoir compartmentalization follows the distribution of facies successions within the intermediate-term cycles. A strong stratigraphic control on reservoir properties occurs at the three scales of stratigraphic cyclicity. In all cases as A/S ratio increases, porosity and permeability decrease.

  3. 4-D stratigraphic architecture and 3-D reservoir zonation of the Mirado Formation, Cusiana Field, Colombia

    SciTech Connect

    Fajardo, A.A.; Cross, T.A.

    1996-12-31

    A high-resolution sequence stratigraphic study using 2300 feet of core calibrated with geophysical logs from 14 wells and 1800 measurements of porosity and permeability established the 4-D stratigraphy and 3-D reservoir zonation of the Mirador. Virtually all reservoir-quality facies are through cross-stratified sandstones which occur in channel facies successions in the lower Mirador, but in bay-head delta and estuarine channel facies successions in the upper Mirador. Petrophysical properties and the geometry, continuity and volume of reservoir-quality sandstones change regularly as function of their stratigraphic position. These vertical facies successions reflect increasing accommodation-to-sediment supply (A/S) ratio through each intermediate-term cycle. The upper long-term cycle comprises four intermediate-term, landward-stepping, symmetrical base-level cycles. These cycles consist of estuarine channel, bay-head to bay-fill facies successions. The transition from channel to bay-head to bay-fill facies successions represents an increase in A/S ratio, and the reverse transition indicates a decrease in A/S ratio. Sixteen reservoir zones were defined within the Cusiana field. Reservoirs within the upper and lower long-term cycles are separated by a continuous middle Mirador mudstone which creates two large reservoir divisions. At the second level of zonation, the reservoir compartments and fluid-flow retardants coincide with the intermediate-term stratigraphic cycles. A third level of reservoir compartmentalization follows the distribution of facies successions within the intermediate-term cycles. A strong stratigraphic control on reservoir properties occurs at the three scales of stratigraphic cyclicity. In all cases as A/S ratio increases, porosity and permeability decrease.

  4. The Stratigraphic Expression of Submarine Channel-Lobe Transitions: An Outcrop Example from Southern Chile

    NASA Astrophysics Data System (ADS)

    Pemberton, Erin A. L.; Hubbard, Stephen M.; Fildani, Andrea; Romans, Brian; Kostic, Svetlana

    2015-04-01

    The stratigraphic expression of sediment-laden gravity flows transitioning from deep-sea submarine channel to less-confined fan lobe is poorly constrained, motivating investigation of outcropping channel-lobe transition zone and channel fills in the Magallanes Basin, southern Chile. We hypothesize that turbidity currents moving from a high-slope confined setting (channel) into a lower slope unconfined setting (lobe), expand laterally and, under the right conditions, undergo internal hydraulic jumps. The Cretaceous strata examined are characterized by a variety of architectural elements in close juxtaposition both laterally and stratigraphically, including: (a) low aspect ratio channelform bodies attributed to slope channel fill; (b) high aspect ratio channelform bodies interpreted as the deposits of weakly-confined turbidite channels; (c) lenticular sedimentary bodies considered to represent the infill of laterally amalgamated scours; (d) discontinuous channelform bodies representing isolated scour fills; and (e) cross-stratified positive relief sedimentary bodies, which record upslope migrating depositional barforms. The ephemeral nature of settings characterized by flow expansion (i.e., channel-lobe transition zone), as well as the propensity for scour and sediment bypass, yields extensive architectural variability in the stratigraphic record. Net-erosional and net-depositional cyclic steps play a fundamental role in the formation, filling, and maintenance phases of channel to lobe transition areas where high gradients support the development of densimetric Froude-supercritical turbidity currents; abrupt slope breaks can, under the right conditions, promote hydraulic jumps and possibly the spontaneous evolution of an erodible seabed into cyclic steps. Along these longitudinal profiles, both the formation of highly composite stratigraphic surfaces, as well as geomorphic surfaces, are passed into the rock record. This yields less repeated stratigraphic patterns than those reported from channel- or lobe- dominated units deposits up- or down- dip of expansion zones.

  5. Integrating age information from different localities for stratigraphic marker beds: discussion of the Eltville Tephra age (Western Europe)

    NASA Astrophysics Data System (ADS)

    Zeeden, Christian; Zens, Joerg; Lehmkuhl, Frank

    2015-04-01

    Stratigraphic marker beds are often used in geosciences for regional and global correlation. For various reasons dating those layers directly proves to be difficult sometimes. In such cases ages from above and below such a horizon represent minimum- and maximum-ages. If these ages are determined from more than one location, it is possible to combine these ages, test their consistency and finally derive an age in agreement with the findings from most localities. Several approaches to integrate the age information from different localities are discussed, resulting in combined ages consistent with both stratigraphy and most of the dating results. All approach rely on assumptions, most importantly the correctness of ages and their reported uncertainty. The Eltville Tephra originates from an unknown eruption in the Eifel volcanic field is an important maker bed in Rhine-Meuse Area nearby the boundary between the deposition of reworked and primary loess during the LGM (ca. 20 ka). The Eltville Tephra is usually imbedded in loess; dates from directly above and below come almost exclusively from luminescence dating. As different luminescence dating techniques were applied to samples over- and underlying the Eltville Tephra a systematic bias of the sum of these techniques seems unlikely, but may be present due to the fact that most ages are feldspar ages uncorrected for fading. The results of several statistical approaches to deal with ages from various localities are compared, and their chances and shortcomings using well understood artificial data are discussed. These are also used to obtain an integrated datum for the Eltville Tephra including a reproducible uncertainty. This has the potential to improve on existing dates for various other stratigraphic marker beds especially in the terrestrial realm, where often dates for (or around) correlative sediments are obtained from various localities.

  6. Polyamine sensitization in offshore workers handling drilling muds.

    PubMed

    Ormerod, A D; Wakeel, R A; Mann, T A; Main, R A; Aldridge, R D

    1989-11-01

    Oil-based mud, a complex mixture containing amines in emulsifiers, is used in offshore drilling operations. It is a skin irritant that occasionally gives rise to allergic contact sensitivity. In patch testing patients with allergy to drilling mud, we have identified polyamine (diethylenetriamine and triethylenetetramine) sensitivity in 5 patients. All 5 patients were also allergic to emulsifiers. These emulsifiers are cross-linked fatty acid amido-amines, in which unreacted amine groups are thought to cross-sensitize with these constituent polyamines. Cross-reactivity between ethylenediamine, diethylenetetramine and triethylenetetramine was found in 9 subjects. PMID:2533536

  7. Exploration for stratigraphic traps in a foreland basin using a sequence stratigraphic simulation: Examples from the Eocene/Oligocene of the Apure-Llanos basin, Venezuela

    SciTech Connect

    Reistroffer, J.; Levine, P.A.; Kendall, C.G.; Finno, A.

    1996-12-31

    Foreland basin depositional sequences provide a sensitive record of the interaction between tectonism, eustatic sea level fluctuations, and sedimentation rates. Interplay between these controlling factors creates sedimentary geometries which are unique to this tectonic setting and form excellent stratigraphic hydrocarbon traps. Incised valley fill deposits, {open_quote}forced regression{close_quote} deposits, and combination structure-stratigraphic traps are the predominant reservoir types. In an effort to extend our understanding of the development of these traps, the sequence stratigraphy of a regional seismic transact through the Apure-Llanos basin was simulated. From the Late Eocene through Oligocene, the Apure-Llanos basin was Characterized by multiple phases of compression and a southeast migrating depocenter. Sands of the Mirador and Carbonera formations, which onlap the Arauca Arch to the southeast, were shed from the Guyana craton and were Cannibalized from sediments along the deformation front to the northwest. These sands comprise the principal reservoirs in the study area. Shales of the Leon Formation, which act as a regional seal, were deposited during rapid flexural subsidence and eustatic sea level rise during the early Oligocene. The Arauca Arch acted as a focal mechanism for east and southeast migrating hydrocarbons. Simulation results predict an important stratigraphic pinchout of the Mirador Formation sands against the Arauca Arch, which correlates with the Arauca Reid in Colombia to the southwest. Also, modeling indicates that minimal Tertiary oil production In the La Victoria Field to the east is due to the lack of an adequate seal. Our results provide a conceptual model which predicts hydrocarbon reservoir and seal relationships in a foreland basin setting with limited data control.

  8. Exploration for stratigraphic traps in a foreland basin using a sequence stratigraphic simulation: Examples from the Eocene/Oligocene of the Apure-Llanos basin, Venezuela

    SciTech Connect

    Reistroffer, J.; Levine, P.A.; Kendall, C.G. ); Finno, A. )

    1996-01-01

    Foreland basin depositional sequences provide a sensitive record of the interaction between tectonism, eustatic sea level fluctuations, and sedimentation rates. Interplay between these controlling factors creates sedimentary geometries which are unique to this tectonic setting and form excellent stratigraphic hydrocarbon traps. Incised valley fill deposits, [open quote]forced regression[close quote] deposits, and combination structure-stratigraphic traps are the predominant reservoir types. In an effort to extend our understanding of the development of these traps, the sequence stratigraphy of a regional seismic transact through the Apure-Llanos basin was simulated. From the Late Eocene through Oligocene, the Apure-Llanos basin was Characterized by multiple phases of compression and a southeast migrating depocenter. Sands of the Mirador and Carbonera formations, which onlap the Arauca Arch to the southeast, were shed from the Guyana craton and were Cannibalized from sediments along the deformation front to the northwest. These sands comprise the principal reservoirs in the study area. Shales of the Leon Formation, which act as a regional seal, were deposited during rapid flexural subsidence and eustatic sea level rise during the early Oligocene. The Arauca Arch acted as a focal mechanism for east and southeast migrating hydrocarbons. Simulation results predict an important stratigraphic pinchout of the Mirador Formation sands against the Arauca Arch, which correlates with the Arauca Reid in Colombia to the southwest. Also, modeling indicates that minimal Tertiary oil production In the La Victoria Field to the east is due to the lack of an adequate seal. Our results provide a conceptual model which predicts hydrocarbon reservoir and seal relationships in a foreland basin setting with limited data control.

  9. Method of installing offshore constructions

    SciTech Connect

    Grosman, I.

    1987-12-08

    A method of constructing and installing an offshore gravity structure type construction in a body of water, by assembling columns of one-by-one using column sections for each individual column is described comprising the steps of: (a) providing a number of hollow, unconnected supporting column sections; (b) transporting the unconnected column sections to a construction site on a sea going vessel; (c) providing only one construction vessel with at least two hoisting systems thereon; (d) arranging, with one hoisting system on the one construction vessel, a single first one of the column sections for a single column near the surface of a body of water; (e) at least submerging with the one hoisting system the single first column section for the single column in the body of water by a certain amount; (f) placing, with another of the at least two hoisting systems, a single second one of the column sections on the top of the first column section and joining the top of the first column section to the bottom of the single second column section near the surface of the body of water to thereby build up a single column; (g) at least partly submerging with one hoisting system the second column section as jointed to the first column section by a depth substantially equal to the length of the second column section; (h) repeatedly placing with another hoisting system on the one construction vessel additional single ones of the column sections; and (i) repeating steps (d) to (h) to form at least a second individual column of desired height by joining column sections one-by-one, the second column being spaced from the first mentioned column, the steps (d) to (h) being repeated until columns are erected in a desired arrangement relative to each other with only the single construction vessel.

  10. The Seabed Stability Zonation in Chinese Offshore

    NASA Astrophysics Data System (ADS)

    Du, J.

    2013-12-01

    There are abundant natural resources and energy in Chinese offshore continental shelf, and which should be the most development potential region now and in the future. But the seabed of Chinese offshore is often under the instable status caused by many factors which deeply affects the safety of marine development. Marine geohazards is an active one among the influence factors. The marine geohazards means the geological factors developed in the seabed surface and the strata below the seabed, such as fault, shallow gas, landslide, coastal erosion, buried river channel, sand wave and sand ridge, easily liquefied sand layer etc., which will cause damage to the human life and property. In this paper, the seabed stability were analyzed and divided it into five grades based on the marine geohazards evaluation result which made by fuzzy mathematic model. Firstly, by collecting the analyzing the marine geohazards which distributed on the seabed or under the seabed, the marine geohazards maps in Chinese offshore were made and the classification system of marine geohazards was established. Then, the evaluation index system of seabed stability was set which included the seismic peak acceleration, geomorphology, direct geohazards and restricted geohazards. And the weighted value of each indicator was calculated by using analytic hierarchy process. And, a group of appropriate number with normal distribution was selected to replace the membership grade function. Based on above, a fuzzy evaluation model for seabed stability is established. Using the maps of marine geohazards, geomorphology maps and seismic peak acceleration maps as data source, using the fuzzy matrix as calculated method, based on the principles of maximum membership grade of fuzzy mathematics, we get the evaluation result of Chinese offshore with 6' by 6' grid unit. The maximum membership grade should be taken as the stability level in each unit. Above all, the seabed stability of Chinese offshore is divided into five grades according to the maximum membership grade. In this paper, we defined 5 classes which respectively were basically stable, relatively stable, medium, relatively unstable and unstable. By using statistical analysis method, a stability zonation map of the Chinese offshore has been drawn based on the evaluation result of each unit. From the stability map, Chinese offshore seabed stability was divided into sixty sub-regions with 5 classes. And the unstable sub-regions were mainly located in the North-East of Liaodong Bay, north of Laizhou Bay, the shoal in north Jiangsu, north Taiwan offshore and around Nan'ao Islands of Guangdong. Most Chinese offshore seabed stability has been in the relatively stable status.

  11. The effects of second-order hydrodynamics on a semisubmersible floating offshore wind turbine

    NASA Astrophysics Data System (ADS)

    Bayati, I.; Jonkman, J.; Robertson, A.; Platt, A.

    2014-06-01

    The objective of this paper is to assess the second-order hydrodynamic effects on a semisubmersible floating offshore wind turbine. Second-order hydrodynamics induce loads and motions at the sum- and difference-frequencies of the incident waves. These effects have often been ignored in offshore wind analysis, under the assumption that they are significantly smaller than first-order effects. The sum- and difference-frequency loads can, however, excite eigenfrequencies of a floating system, leading to large oscillations that strain the mooring system or vibrations that cause fatigue damage to the structure. Observations of supposed second-order responses in wave-tank tests performed by the DeepCwind consortium at the Maritime Research Institute Netherlands (MARIN) offshore basin suggest that these effects might be more important than originally expected. These observations inspired interest in investigating how second-order excitation affects floating offshore wind turbines and whether second-order hydrodynamics should be included in offshore wind simulation tools like FAST. In this work, the effects of second-order hydrodynamics on a floating semisubmersible offshore wind turbine are investigated. Because FAST is currently unable to account for second-order effects, a method to assess these effects was applied in which linearized properties of the floating wind system derived from FAST (including the 6x6 mass and stiffness matrices) are used by WAMIT to solve the first- and second-order hydrodynamics problems in the frequency domain. The method was applied to the Offshore Code Comparison Collaboration Continuation OC4-DeepCwind semisubmersible platform, supporting the National Renewable Energy Laboratory's 5-MW baseline wind turbine. In this paper, the loads and response of the system caused by the second-order hydrodynamics are analysed and compared to the first-order hydrodynamic loads and induced motions in the frequency domain. Further, the second-order loads and induced response data are compared to the loads and motions induced by aerodynamic loading as solved by FAST.

  12. A framework for offshore vendor capability development

    NASA Astrophysics Data System (ADS)

    Yusuf Wibisono, Yogi; Govindaraju, Rajesri; Irianto, Dradjad; Sudirman, Iman

    2016-02-01

    Offshore outsourcing is a common practice conducted by companies, especially in developed countries, by relocating one or more their business processes to other companies abroad, especially in developing countries. This practice grows rapidly owing to the ease of accessing qualified vendors with a lower cost. Vendors in developing countries compete more intensely to acquire offshore projects. Indonesia is still below India, China, Malaysia as main global offshore destinations. Vendor capability is among other factors that contribute to the inability of Indonesian vendor in competing with other companies in the global market. Therefore, it is essential to study how to increase the vendor's capability in Indonesia, in the context of global offshore outsourcing. Previous studies on the vendor's capability mainly focus on capabilities without considering the dynamic of capabilities due to the environmental changes. In order to be able to compete with competitors and maintain the competitive advantage, it is necessary for vendors to develop their capabilities continuously. The purpose of this study is to develop a framework that describes offshore vendor capability development along the client-vendor relationship stages. The framework consists of three main components, i.e. the stages of client-vendor relationship, the success of each stage, and the capabilities of vendor at each stage.

  13. Offshore oil gas trends in ROVs tooling

    SciTech Connect

    Jacobson, J.R. )

    1994-04-01

    The ROVs that operate in today's offshore environment bear little or no resemblance to those which first began supporting the oil and gas work requirements less than 15 years ago. In that short span of time, an explosion of subsea technology has occurred, rendering older equipment obsolete and expanding subsea remote intervention capabilities beyond the horizon of intervention tasks originally envisioned. Today's offshore work ROVs employ the latest in robotics, fiver optics, acoustics, video, and computer technologies, and routinely achieve better than 90 percent operational availability. Leading offshore ROV operations companies have demonstrated less than 1 percent down-time over thousands of hours of operation. As the offshore oil and gas market evolves, the ever-expanding capabilities of the work ROV plays a major role in shaping the operational concepts employed in subsea oil and gas field exploration, development, and production. This paper explores the capabilities of available ROV systems in use offshore today, the economic trends driving ROV technology development, and the new trends in the employment of ROVs and their associated sensors and tooling systems.

  14. Operational management of offshore energy assets

    NASA Astrophysics Data System (ADS)

    Kolios, A. J.; Martinez Luengo, M.

    2016-02-01

    Energy assets and especially those deployed offshore are subject to a variety of harsh operational and environmental conditions which lead to deterioration of their performance and structural capacity over time. The aim of reduction of CAPEX in new installations shifts focus to operational management to monitor and assess performance of critical assets ensuring their fitness for service throughout their service life and also to provide appropriate and effective information towards requalification or other end of life scenarios, optimizing the OPEX. Over the last decades, the offshore oil & gas industry has developed and applied various approaches in operational management of assets through Structural Health and Condition Monitoring (SHM/CM) systems which can be, at a certain level, transferable to offshore renewable installations. This paper aims to highlight the key differences between offshore oil & gas and renewable energy assets from a structural integrity and reliability perspective, provide a comprehensive overview of different approaches that are available and applicable, and distinguish the benefits of such systems in the efficient operation of offshore energy assets.

  15. Federal Offshore Statistics, 1993. Leasing, exploration, production, and revenue as of December 31, 1993

    SciTech Connect

    Francois, D.K.

    1994-12-31

    This document contains statistical data on the following: federal offshore lands; offshore leasing activity and status; offshore development activity; offshore production of crude oil and natural gas; federal offshore oil and natural gas sales volume and royalties; revenue from federal offshore leases; disbursement of federal offshore revenue; reserves and resource estimates of offshore oil and natural gas; oil pollution in US and international waters; and international activities and marine minerals. A glossary is included.

  16. Investigation on installation of offshore wind turbines

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bai, Yong

    2010-06-01

    Wind power has made rapid progress and should gain significance as an energy resource, given growing interest in renewable energy and clean energy. Offshore wind energy resources have attracted significant attention, as, compared with land-based wind energy resources, offshore wind energy resources are more promising candidates for development. Sea winds are generally stronger and more reliable and with improvements in technology, the sea has become a hot spot for new designs and installation methods for wind turbines. In the present paper, based on experience building offshore wind farms, recommended foundation styles have been examined. Furthermore, wave effects have been investigated. The split installation and overall installation have been illustrated. Methods appropriate when installing a small number of turbines as well as those useful when installing large numbers of turbines were analyzed. This investigation of installation methods for wind turbines should provide practical technical guidance for their installation.

  17. Solar power satellite offshore rectenna study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Offshore rectennas are feasible and cost competitive with land rectennas but the type of rectenna suitable for offshore use is quite different from that specified in the present reference system. A nonground plane design minimizes the weight and greatly reduces the number of costly support towers. This perferred design is an antenna array consisting of individually encapsulated dipoles with reflectors or tagis supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane, winter storm, and icing conditions for a one time cost of $5.7 billion. Subsequent units would be about 1.3 less expensive. More benign and more shallow water sites would result in substantially lower costs. The major advantage of an offshore rectenna is the removal of microwave radiation from populated areas.

  18. 76 FR 24504 - National Offshore Safety Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-02

    ... make recommendations on same. (7) Update from other interagency organizations; Bureau of Ocean Energy... SECURITY National Offshore Safety Advisory Committee AGENCY: United States Coast Guard, DHS. ACTION: Committee Management; Notice of Federal Advisory Committee Meeting. SUMMARY: The National Offshore...

  19. Strengthening America's Energy Security with Offshore Wind (Fact Sheet)

    SciTech Connect

    Not Available

    2012-02-01

    This fact sheet describes the current state of the offshore wind industry in the United States and the offshore wind research and development activities conducted the U.S. Department of Energy Wind and Water Power Program.

  20. National Offshore Wind Energy Grid Interconnection Study Executive Summary

    SciTech Connect

    Daniel, John P.; Liu, Shu; Ibanez, Eduardo; Pennock, Ken; Reed, Gregory; Hanes, Spencer

    2014-07-30

    The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States.

  1. 75 FR 80064 - National Offshore Safety Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-21

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF HOMELAND SECURITY Coast Guard National Offshore Safety Advisory Committee AGENCY: Coast Guard, DHS. ACTION: Notice of teleconference meeting. SUMMARY: The National Offshore Safety Advisory Committee (NOSAC) will...

  2. 75 FR 47311 - National Offshore Safety Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-05

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard National Offshore Safety Advisory Committee AGENCY: Coast Guard, DHS. ACTION: Notice of open teleconference meeting. SUMMARY: The National Offshore Safety Advisory Committee (NOSAC)...

  3. 46 CFR 90.10-40 - Offshore supply vessels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., supplies or equipment in support of exploration, exploitation, or production of offshore mineral or energy resources. (b) An existing offshore supply vessel is one contracted for, or the keel of which was...

  4. 46 CFR 90.10-40 - Offshore supply vessels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., supplies or equipment in support of exploration, exploitation, or production of offshore mineral or energy resources. (b) An existing offshore supply vessel is one contracted for, or the keel of which was...

  5. 46 CFR 90.10-40 - Offshore supply vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., supplies or equipment in support of exploration, exploitation, or production of offshore mineral or energy resources. (b) An existing offshore supply vessel is one contracted for, or the keel of which was...

  6. 46 CFR 90.10-40 - Offshore supply vessels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., supplies or equipment in support of exploration, exploitation, or production of offshore mineral or energy resources. (b) An existing offshore supply vessel is one contracted for, or the keel of which was...

  7. National Offshore Wind Energy Grid Interconnection Study Full Report

    SciTech Connect

    Daniel, John P.; Liu, Shu; Ibanez, Eduardo; Pennock, Ken; Reed, Gregory; Hanes, Spencer

    2014-07-30

    The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States.

  8. Exploration potential of offshore northern California basins

    SciTech Connect

    Bachman, S.B.; Crouch, J.K.

    1988-01-01

    A series of exploratory wells was drilled in the northern California offshore basins in the 1960s following leasing of federal tracts off northern California, Oregon, and Washington. The drilling, although encountering numerous oil shows, was considered at the time to indicate low prospectivity in an area that extended as far south as the offshore Santa Maria basin. However, subsequent major discoveries in this decade in the offshore Santa Maria basin, such as the Point Arguello field, indicate that these offshore basins may be highly prospective exploration targets. Many of the key features of Monterey production in central and southern California are also present in the offshore basins of northern California. A new 5-year leasing plan has scheduled leasing in the northern California OCS starting in early 1989. The first basins on the schedule, the Point Arena and Eel River basins, differ in some respects. The Point Arena basin is more typical of a Monterey basin, with the potential for fractured chert reservoirs and organic-rich sections, deep burial of basinal sections to enhance the generation of higher gravity oils, and complex folding and faulting. The Eel River basin is more clastic-rich in its gas-producing, onshore extension. Key questions in the Eel River basin include whether the offshore, more distal stratigraphy will include Monterey-like biogenic sediments, and whether the basin has oil potential in addition to its proven gas potential. The Outer Santa Cruz basin shares a similar stratigraphy, structure, and hydrocarbon potential with the Point Arena basin. The Santa Cruz-Bodega basin, also with a similar stratigraphy, may have less exploration potential because erosion has thinned the Monterey section in parts of the basin.

  9. Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint

    SciTech Connect

    Roald, L.; Jonkman, J.; Robertson, A,; Chokani, N.

    2013-07-01

    Offshore winds are generally stronger and more consistent than winds on land, making the offshore environment attractive for wind energy development. A large part of the offshore wind resource is however located in deep water, where floating turbines are the only economical way of harvesting the energy. The design of offshore floating wind turbines relies on the use of modeling tools that can simulate the entire coupled system behavior. At present, most of these tools include only first-order hydrodynamic theory. However, observations of supposed second-order hydrodynamic responses in wave-tank tests performed by the DeepCwind consortium suggest that second-order effects might be critical. In this paper, the methodology used by the oil and gas industry has been modified to apply to the analysis of floating wind turbines, and is used to assess the effect of second-order hydrodynamics on floating offshore wind turbines. The method relies on combined use of the frequency-domain tool WAMIT and the time-domain tool FAST. The proposed assessment method has been applied to two different floating wind concepts, a spar and a tension-leg-platform (TLP), both supporting the NREL 5-MW baseline wind turbine. Results showing the hydrodynamic forces and motion response for these systems are presented and analysed, and compared to aerodynamic effects.

  10. The proceedings of the fourth (1994) international offshore and polar engineering conference. Volume 4

    SciTech Connect

    Ueda, Yukio; Tomita, Yasumitsu; Dos Santos, J.F.; Langen, I.; Waagaard, K.

    1994-12-31

    This conference proceedings is one volume of a four volume set dealing with oil and gas industry operations in polar and offshore environments. This particular conference deals primarily with materials and designs for offshore platforms and tanker ships. It provides papers dealing with concretes, steels, and composite materials and the IR mechanical properties. Many papers review testing and processes for welded joints. It also provides papers which deal with fracture mechanics and corrosion protection. Approximately 74 papers have been individually abstracted and entered into the data base.

  11. Flexible liner safeguards environment during offshore workover

    SciTech Connect

    Not Available

    1991-06-10

    A Total-containment liner was installed on the upper deck of a Louisiana offshore platform in West Cameron 593A, by Unocal Exploration Corp. The liner will help protect the environment during workover operations. Unocal's major environmental concern was the oilbased packer fluid used in the wells. Even though the platform workover rig, Hercules; Rig 11, was equipped with containment equipment which met federal regulations, Unocal wanted a secondary containment device to further guarantee that an accidental spill would not occur, according to Clyde Landry, Unocal's district production manager for the west offshore district, Louisiana region.

  12. NWTC Helps Guide U.S. Offshore R&D; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-07-01

    The National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) is helping guide our nation's research-and-development effort in offshore renewable energy, which includes: Design, modeling, and analysis tools; Device and component testing; Resource characterization; Economic modeling and analysis; Grid integration.

  13. 46 CFR 15.520 - Mobile offshore drilling units.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Mobile offshore drilling units. 15.520 Section 15.520... REQUIREMENTS Manning Requirements; Inspected Vessels 15.520 Mobile offshore drilling units. (a) The requirements in this section for mobile offshore drilling units (MODUs) supplement other requirements in...

  14. 46 CFR 111.105-33 - Mobile offshore drilling units.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mobile offshore drilling units. 111.105-33 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations 111.105-33 Mobile offshore drilling units. (a) Applicability. This section applies to each mobile offshore drilling unit. (b) Definitions. As used in...

  15. 46 CFR 111.105-33 - Mobile offshore drilling units.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mobile offshore drilling units. 111.105-33 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations 111.105-33 Mobile offshore drilling units. (a) Applicability. This section applies to each mobile offshore drilling unit. (b) Definitions. As used in...

  16. 46 CFR 111.105-33 - Mobile offshore drilling units.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mobile offshore drilling units. 111.105-33 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations 111.105-33 Mobile offshore drilling units. (a) Applicability. This section applies to each mobile offshore drilling unit. (b) Definitions. As used in...

  17. 46 CFR 15.520 - Mobile offshore drilling units (MODUs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Mobile offshore drilling units (MODUs). 15.520 Section... MANNING REQUIREMENTS Manning Requirements; Inspected Vessels 15.520 Mobile offshore drilling units... endorsement on an MMC as offshore installation manager (OIM), barge supervisor (BS), or ballast...

  18. 46 CFR 15.520 - Mobile offshore drilling units.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Mobile offshore drilling units. 15.520 Section 15.520... REQUIREMENTS Manning Requirements; Inspected Vessels 15.520 Mobile offshore drilling units. (a) The requirements in this section for mobile offshore drilling units (MODUs) supplement other requirements in...

  19. 77 FR 4572 - National Offshore Safety Advisory Committee; Vacancies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-30

    ... exploration of offshore mineral and energy resources insofar as they relate to matters within Coast Guard... activities directly involved with or in support of the exploration of offshore mineral and energy resources... mineral and energy industry; (b) One member representing Diving Services related to offshore...

  20. 46 CFR 15.520 - Mobile offshore drilling units.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Mobile offshore drilling units. 15.520 Section 15.520... REQUIREMENTS Manning Requirements; Inspected Vessels § 15.520 Mobile offshore drilling units. (a) The requirements in this section for mobile offshore drilling units (MODUs) supplement other requirements in...

  1. 46 CFR 111.105-33 - Mobile offshore drilling units.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mobile offshore drilling units. 111.105-33 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations § 111.105-33 Mobile offshore drilling units. (a) Applicability. This section applies to each mobile offshore drilling unit. (b) Definitions. As used in...

  2. 46 CFR 15.520 - Mobile offshore drilling units.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Mobile offshore drilling units. 15.520 Section 15.520... REQUIREMENTS Manning Requirements; Inspected Vessels § 15.520 Mobile offshore drilling units. (a) The requirements in this section for mobile offshore drilling units (MODUs) supplement other requirements in...

  3. 46 CFR 111.105-33 - Mobile offshore drilling units.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mobile offshore drilling units. 111.105-33 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Hazardous Locations § 111.105-33 Mobile offshore drilling units. (a) Applicability. This section applies to each mobile offshore drilling unit. (b) Definitions. As used in...

  4. 47 CFR 22.1037 - Application requirements for offshore stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Application requirements for offshore stations. 22.1037 Section 22.1037 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Offshore Radiotelephone Service § 22.1037 Application requirements for offshore stations. Applications for...

  5. International Offshore Students' Perceptions of Virtual Office Hours

    ERIC Educational Resources Information Center

    Wdowik, Steven; Michael, Kathy

    2013-01-01

    Purpose: The main aim of this study is to gauge international offshore students' perceptions of virtual office hours (VOH) to consult with their offshore unit coordinators in Australia. Design/methodology/approach: This paper employs a quantitative and qualitative approach where data was sourced from three offshore campuses over a 12-month period

  6. Evolution and Reduction of Scour around Offshore Wind Turbines

    NASA Astrophysics Data System (ADS)

    McGovern, David; Ilic, Suzana

    2010-05-01

    Evolution and Reduction of Scour around Offshore Wind Turbines In response to growing socio-economic and environmental demands, electricity generation through offshore wind turbine farms is a fast growing sector of the renewable energy market. Considerable numbers of offshore wind farms exist in the shallow continental shelf seas of the North-West Europe, with many more in the planning stages. Wind energy is harnessed by large rotating blades that drive an electricity generating turbine placed on top of a long cylindrical monopile that are driven into the sea-bed, well into the bed rock below the sediment. Offshore wind turbines are popular due to consistently higher wind speeds and lower visual impact than their onshore counter parts, but their construction and maintenance is not without its difficulties. The alteration of flow by the presence of the wind turbine monopile results in changes in sedimentary processes and morphology at its base. The increase in flow velocity and turbulence causes an amplification of bed shear stress and this can result in the creation of a large scour hole at the monopile base. Such a scour hole can adversely affect the structural integrity and hence longevity of the monopile. Changes to the sea bed caused by this may also locally affect the benthic habitat. We conducted an extensive series of rigid and mobile bed experiments to examine the process of scour under tidal currents. We also test the effectiveness of a flow-altering collared monopile in reducing scour. Firstly, we used Particle Image Velocimetry (PIV) and Acoustic Doppler Velocimetry (ADV) to visualise and analyse the flow and turbulence properties in the local flow around the monopile and collared monopile over a smooth rigid bed under tidal flow. The measured flow, turbulence and shear stress properties are related to mobile bed tests where a Seatek 5 MHz Ultrasonic Ranging system is used to identify the evolution of scour under reversing tidal currents. The tidal evolution of the scour hole around the monopile is compared with that under unidirectional currents and that around the collared monopile. Results show that the evolution of scour under tidal currents is quite different than that of a unidirectional current and that the scour hole shape is also more symmetrical than the scour hole under a unidirectional current, which is quite asymmetrical. Results also indicate that the collared monopile design is effective in reducing the depth of scour that occurs at its base. This data will also be used for a validation of the numerical model of scour processes around the pile. Key words: Monopile, Scour, Tidal Flow, Scour Reduction

  7. United States Offshore Wind Resource Assessment

    NASA Astrophysics Data System (ADS)

    Schwartz, M.; Haymes, S.; Heimiller, D.

    2008-12-01

    The utilization of the offshore wind resource will be necessary if the United States is to meet the goal of having 20% of its electricity generated by wind power because many of the electrical load centers in the country are located along the coastlines. The United States Department of Energy, through its National Renewable Energy Laboratory (NREL), has supported an ongoing project to assess the wind resource for the offshore regions of the contiguous United States including the Great Lakes. Final offshore maps with a horizontal resolution of 200 meters (m) have been completed for Texas, Louisiana, Georgia, northern New England, and the Great Lakes. The ocean wind resource maps extend from the coastline to 50 nautical miles (nm) offshore. The Great Lake maps show the resource for all of the individual lakes. These maps depict the wind resource at 50 m above the water as classes of wind power density. Class 1 represents the lowest available wind resource, while Class 7 is the highest resource. Areas with Class 5 and higher wind resource can be economical for offshore project development. As offshore wind turbine technology improves, areas with Class 4 and higher resource should become economically viable. The wind resource maps are generated using output from a modified numerical weather prediction model combined with a wind flow model. The preliminary modeling is performed by AWS Truewind under subcontract to NREL. The preliminary model estimates are sent to NREL to be validated. NREL validates the preliminary estimates by comparing 50 m model data to available measurements that are extrapolated to 50 m. The validation results are used to modify the preliminary map and produce the final resource map. The sources of offshore wind measurement data include buoys, automated stations, lighthouses, and satellite- derived ocean wind speed data. The wind electric potential is represented as Megawatts (MW) of potential installed capacity and is based on the square kilometers (sq. km) of Class 5 and higher wind resource found in a specific region. NREL uses a factor of 5 MW of installed capacity per sq. km of "windy water" for its raw electric potential calculations. NREL uses Geographic Information System data to break down the offshore wind potential by state, water depth, and distance from shore. The wind potential estimates are based on the updated maps, and on previous offshore resource information for regions where new maps are not available. The estimates are updated as new maps are completed. For example, the updated Texas offshore map shows almost 3000 sq. km of Class 5 resource within 10 nm of shore and nearly 2000 sq. km of Class 5 resource or 10,000 MW of potential installed capacity in water depths of less than 30 m. NREL plans to develop exclusion criteria to further refine the offshore wind potential

  8. An integrated sequence stratigraphic and chronostratigraphic analysis of the Pliocene, Tiburon Basin succession, Mejillones Peninsula, Chile

    NASA Astrophysics Data System (ADS)

    Tapia, Claudio A.; Wilson, Gary S.; Ishman, Scott E.; Wilke, Hans G.; Wartho, Jo-Anne; Winter, Diane; Martnez-Pardo, Rubn

    2015-08-01

    We present new findings from Pliocene marine sediments from the Mejillones Peninsula Tiburon Basin of the northern Chile continental margin that provide constraints for the global sea level record. Sedimentologic and sequence stratigraphic studies reveal facies associations of a continental shelf setting. Textural variations indicate that coarsening and fining up of the succession are due to relative sea level rise and fall, respectively. Magnetostratigraphy was integrated with bio- and tephro- stratigraphic data to construct a record of high-resolution chronology. The age model constrains the Tiburon Basin lower section between 4.2 Ma and 2.8 Ma. The record is likely to be controlled in part by sea level change with orbital periodicities of obliquity (? 40 ka of frequency) and, between 3.2 Ma and 2.9 Ma a high-amplitude sea level fall is correlated to global climatic deterioration and the onset of major Northern Hemisphere glaciations.

  9. The stratigraphic sequence of volcanic and sedimentary units in the north polar region of Mars

    NASA Technical Reports Server (NTRS)

    Botts, M. E.

    1980-01-01

    Based on photogeologic mapping of Viking orbiter images of Mars, four distinct informal stratigraphic units are defined for the region north of 70 degrees N latitude. They are: (a) bulbous plains, (b) mantled plains, (c) dune deposits, and (d) layered deposits/perennial ice. Background information on the Martian polar caps is provided from telescopic observation, Mariner mission results, and Viking mission results (August 1976-November 1978). A description, and an interpretation and distribution of the stratigraphic units are presented. Surface winds, which were determined from dune orientations, and discussed and implications for the source of circumpolar dune materials are delineated. A list of the Viking Orbiter imagery used in the research, the computer programs for crater size frequency distributions, and the crater size frequency data are presented.

  10. Stratigraphic Subdivision of the Transvaal Dolomite from ERTS imagery. [South Africa

    NASA Technical Reports Server (NTRS)

    Grootenboer, J.; Eriksson, K.; Truswell, J.

    1974-01-01

    ERTS imagery has revealed the presence of broad stratigraphic subdivisions in the previously undifferentiated Transvaal Dolomite of the western Tranvaal, Republic of South Africa. While detailed field mapping in areas of good outcrop, as well as borehole logging has recently led to the recognition of a stratigraphy in the Transvaal Dolomite of the central Transvaal, poor outcrop in the western Transvaal has to date prevented this. The ERTS-imagery, however, clearly reveals the presence of six, and in the far west seven, distinct stratigraphic zones extending along strike for a distance of at least 200 km. The investigation clearly demonstrates the potential applications of ERTS-imagery in geological studies, even in a country where the geology is supposedly well known.

  11. Tectono-stratigraphic development of the Coastal Group of south-eastern Jamaica

    NASA Astrophysics Data System (ADS)

    James-Williamson, Sherene A.; Mitchell, Simon F.; Ramsook, Ryan

    2014-03-01

    The sedimentary succession of southeastern Jamaica preserves a depositional record of accommodation changes and tectonic events for the last 14 Ma. The depositional systems which occur in the area have been classified according to distinct tectono-stratigraphic packages based on the depositional environments, rapid facies changes, and or significant erosion surfaces. This paper places the sedimentology and geochemistry within a tectonic evolutionary framework for the northern margin of the Caribbean Plate over the last 14 Ma. This involves considering issues of changing accommodation; deformation episodes including folding and faulting and the subsequent cutting of unconformities. A model for the tectono-stratigraphic development of southeastern Jamaica is also proposed. The model incorporates critical surfaces, major faults, subsidence and uplift which later influence the depositional environments.

  12. An assessment of the mechanical stability of wells offshore Nigeria

    SciTech Connect

    Lowrey, J.P.; Ottesen, S.

    1995-03-01

    In 1991 lost time due to stuck pipe related drilling problems accounted for approximately 18% of total drilling time in Mobil Producing Nigeria Ultd.`s (MPN) offshore operations. The primary cause of stuck pipe was identified as mechanical wellbore instability. This paper presents an assessment of the mechanical stability of MPN`s wells offshore Nigeria. The objectives of the study were to: (1) determine the magnitude of the in-situ principal stresses and material properties of the troublesome Intra-Biafra and Qua Iboe shale sequences; (2) quantify the drilling fluid densities required to drill mechanically stable wells through these formations; (3) review and recommend well planning and operational parameters which aid in minimizing wellbore stability-related drilling problems. The well-bore stability assessment was carried out with the aid of a 3-dimensional wellbore stability model using field derived data from the study area to corroborate the results. The collection and analysis of drilling data (borehole geometry and density logs, pore pressure, leak-off tests, local geology and other relevant well records) to determine the magnitude of the in-situ principal stresses, together with compressive strength tests on formation cores are discussed. Minimum safe drilling fluid densities to promote wellbore stability as a function of well geometry and depth are presented for the most troublesome shales drilled in the study area. Implementation of the results reduced wellbore stability related problems and associated trouble time to less than 5% in 1992.

  13. Detection and stratigraphic mapping of spectrally distinct hydrated layers in equatorial regions of Mars

    NASA Astrophysics Data System (ADS)

    Sefton-Nash, E.; Teanby, N. A.

    2011-10-01

    We demonstrate the use of spectral and topographic data to map spectrally distinct rock units spatially, in elevation and in stratigraphy. Using hyperspectral data from NASA's CRISM and stereo-derived topographic data from ESA's HRSC we present the first results of a project to map geologic units containing hydrated minerals in equatorial regions of Mars (e.g. Valles Marineris, Xanthe Terra and Margaritifer Terra) and to correlate their stratigraphic position with existing formation theories.

  14. Remote Stratigraphic Analysis: Combined TM and AIS Results in the Wind River/bighorn Basin Area, Wyoming

    NASA Technical Reports Server (NTRS)

    Lang, H. R.; Paylor, E. D.; Adams, S.

    1985-01-01

    An in-progress study demonstrates the utility of airborne imaging spectrometer (AIS) data for unraveling the stratigraphic evolution of a North American, western interior foreland basin. AIS data are used to determine the stratigraphic distribution of mineralogical facies that are diagnostic of specific depositional environments. After wavelength and amplitude calibration using natural ground targets with known spectral characteristics, AIS data identify calcite, dolomite, gypsum and montmorillonite-bearing strata in the Permian-Cretaceous sequence. Combined AIS and TM results illustrate the feasibility of spectral stratigraphy, remote analysis of stratigraphic sequences.

  15. Fatigue crack propagation in high strength steels for use offshore

    SciTech Connect

    Billingham, J.; Laws, P.A.

    1994-12-31

    The influence of applied cathodic protection levels on the corrosion fatigue crack propagation behavior of a number of welded high strength microalloyed steels has been determined. The types of steel and the yield strengths selected, which ranged from 450 to 650MPa, were intended to cover both existing and likely developments in offshore structures over the next decade or so. The steels were welded using the submerged arc process at a heat input of 3kJ/mm and the corrosion fatigue properties of the coarse grained heat affected zones (CGHAZ) were examined using S.E.N. specimens subjected to a loading frequency of 0.5Hz and a load ratio of 0.6 in a synthetic seawater solution. At high over potentials ({minus}1100mV) all steels showed significantly enhanced corrosion fatigue crack propagation rates compared to similar samples protected at {minus}800mV. Growth rates of up to an order of magnitude faster were measured in some cases. Crack path deviation in general decreased as the potential decreased. Much flatter, cleavage type modes of fracture propagation were sometimes observed, indicating that the faster growth rates were associated with hydrogen embrittlement problems caused by the excess hydrogen generated by the cathodic protection process. However, the resulting fatigue performance was found to be no worse than for conventional lower strength 350MPa structural steels which are presently being used offshore. The work examined the influence of alloy composition and microstructure on fatigue crack growth behavior and emphasizes the difficulties associated with assessing and comparing fatigue behavior of welded samples because of the different microstructures which are sampled by the growing fatigue crack tip in conventional test procedures. Finally, the work makes recommendation on suitable high strength alloy types for further development for offshore applications.

  16. Application of low density foam pigs offshore Brazil

    SciTech Connect

    Lima, P.C.R.; Alves, S.J.

    1995-12-31

    In complex offshore installations, such as in the Campos Basin, it is relatively common to encounter pipeline systems where conventional pigs can not be run due to several factors. Changing pipe diameters, and presence of wet X-mas trees and manifolds are the most troublesome ones. In this work a new successful concept of using low cost and low density foam pigs for both liquid removal in wet-gas pipelines, and paraffin removal in oil and multiphase flow pipelines, is presented. Experimental work conducted in a 4 in laboratory facility, including a small scale glass manifold and a 6 in steel manifold, proved these pigs to be very effective. The performance of almost all kind of flexible polyurethane foams manufactured in Brazil is evaluated. Three field tests are also reported. The first low density foam pig operation was performed on a 127 mile long, 16 in diameter wet-gas offshore pipeline where the foam pig showed even higher liquid removal efficiency than the conventional inflatable spheres. The second operation was performed on a 6 mile long, 12 in diameter multiphase production offshore pipeline, which has never been pigged during its 9 year operation, and resulted in the removal of approximately 200 tons of paraffin. Finally, the third successful case is the cleaning of a 2 mile long flexible flow line of a subsea completed satellite well, in which the foam pigs were sent through a 2.5 in gas lift line, through a wet x-mas tree, not designed to be pigged, and then back through the 4 in production flow line. In spite of the fact that this paper is focusing on condensate and paraffin removal in pipeline, the basic principles can be applied to several kinds of operations: general pipeline cleaning; products separation in pipeline; corrosion evaluation; chemical product application.

  17. Stratigraphic Context of Old Crow Tephra, Holitna Lowland, Interior Southwest Alaska

    USGS Publications Warehouse

    Waythomas, C.F.; Lea, P.D.; Walter, R.C.

    1993-01-01

    A thick deposit of Old Crow tephra was discovered in a bluff exposure along the middle Holitna River near the Kulukbuk Hills (61??20???N latitude, 157??10???W longitude) in interior southwest Alaska. This locality is the southwesternmost-known deposit of Old Crow tephra in Alaska. Thickness and grain-size data from this site support a source volcano in the eastern Aleutian arc. Pleistocene stratigraphic sequences in the lowland are dominated by upward-fining eolian sand-sheet deposits and loess separated by organic silt. These deposits record at least two episodes of regional glaciation and an intervening nonglacial period (marine oxygen isotope stage 3, stage 5, or both). Old Crow tephra crops out near the top of the lower upward-fining eolian unit, indicating that the ash erupted near the end of an interval of periglacial eolian sedimentation. The sequence of eolian deposits that contain Old Crow tephra probably accumulated during the latter part of marine oxygen isotope stage 6, whereas the overlying eolian sequence formed during the last glaciation (stage 2). This stratigraphic position is consistent with other stratigraphic contexts for the tephra and with fission-track and thermoluminescence ages of ca. 140,000 ?? 10,000 yr B.P.

  18. Examination of spaceborne imaging spectroscopy data utility for stratigraphic and lithologic mapping

    NASA Astrophysics Data System (ADS)

    Dadon, Alon; Ben-Dor, Eyal; Beyth, Michael; Karnieli, Arnon

    2011-01-01

    Due to the increasing development of image spectroscopy techniques, airborne and spaceborne hyperspectral images have in recent years become readily available for use in geological applications. One of the prominent advantages of imaging spectroscopy is its high spectral resolution, producing detailed spectral information in each pixel. The current study aims at exploring the feasibility of the Earth-Observing-1 Hyperion imaging spectrometer to map the geology arena over the Dana Geology National Park, Jordan. After overcoming the common preprocessing difficulties (e.g., smile effect), a classification scheme of two levels was applied. The first level resulted in a stratigraphic classification product of eleven classes and the second level in a lithologic classification product of six classes. The overall accuracy of the stratigraphic product was 57%, while that of the lithologic product was 79%. Mismatches in classification were mostly related to terrestrial cover of the lower topography formation by rock and sand debris. In addition, low accuracy values can be attributed to Hyperion's high sensitivity, leading to recognition of different mineral compositions as different classes within a rock formation, while the conventional geology-stratigraphic map generalizes these different classes into one formation. The methods practiced in the current research can advance the Hyperion's classification capabilities and therefore can be applied in different geological settings and additional disciplines such as penology, agriculture, ecology, forestry, urban, and other environmental studies.

  19. Spheroidal carbonaceous particles are a defining stratigraphic marker for the Anthropocene

    PubMed Central

    Swindles, Graeme T.; Watson, Elizabeth; Turner, T. Edward; Galloway, Jennifer M.; Hadlari, Thomas; Wheeler, Jane; Bacon, Karen L.

    2015-01-01

    There has been recent debate over stratigraphic markers used to demarcate the Anthropocene from the Holocene Epoch. However, many of the proposed markers are found only in limited areas of the world or do not reflect human impacts on the environment. Here we show that spheroidal carbonaceous particles (SCPs), a distinct form of black carbon produced from burning fossil fuels in energy production and heavy industry, provide unambiguous stratigraphic markers of the human activities that have rapidly changed planet Earth over the last century. SCPs are found in terrestrial and marine sediments or ice cores in every continent, including remote areas such as the high Arctic and Antarctica. The rapid increase in SCPs mostly occurs in the mid-twentieth century and is contemporaneous with the ‘Great Acceleration’. It therefore reflects the intensification of fossil fuel usage and can be traced across the globe. We integrate global records of SCPs and propose that the global rapid increase in SCPs in sedimentary records can be used to inform a Global Standard Stratigraphic Age for the Anthropocene. A high-resolution SCP sequence from a lake or peatland may provide the much-needed ‘Golden Spike’ (Global Boundary Stratotype Section and Point). PMID:26020614

  20. Use of gravel provenance to define stratigraphic units in the Sandia Windgap trench, Livermore, California

    SciTech Connect

    Wagoner, J.L. ); Hedegaard, R.F.; Barber, K.

    1993-04-01

    The Sandia Windgap was trenched as part of an ongoing investigation of the stratigraphy, origin, and correlation of fluvial gravels beneath the Lawrence Livermore National Laboratory (LLNL). This windgap, an uplifted and abandoned drainage system, is located on a horst between the north and south branches of the Las Positas Fault. Two trenches exposed nonmarine clastic sediments of the Upper and Lower Livermore Formations, as well as potentially younger gravel deposits associated with paleodrainage systems through the windgap. The purpose of this investigation is to define and correlate individual stratigraphic units, based on the provenance of the gravel fraction. Eighteen different gravel deposits were sampled in the trench. Sampling was done using a bulk sampling method, and the gravels were processed in the laboratory. Several different size fractions were analyzed, and the detrital clasts were identified and counted both macroscopically and using a stereomicroscope. Thin sections of selected lithologies were constructed for accurate lithologic classification. The source of these deposits is compared to subsurface gravels collected from boreholes drilled on the LLNL site. This investigation will aid in the identification and correlation of stratigraphic units in the subsurface and enhance the understanding of the three-dimensional stratigraphic framework which controls the migration of contaminants beneath LLNL.

  1. Spheroidal carbonaceous particles are a defining stratigraphic marker for the Anthropocene.

    PubMed

    Swindles, Graeme T; Watson, Elizabeth; Turner, T Edward; Galloway, Jennifer M; Hadlari, Thomas; Wheeler, Jane; Bacon, Karen L

    2015-01-01

    There has been recent debate over stratigraphic markers used to demarcate the Anthropocene from the Holocene Epoch. However, many of the proposed markers are found only in limited areas of the world or do not reflect human impacts on the environment. Here we show that spheroidal carbonaceous particles (SCPs), a distinct form of black carbon produced from burning fossil fuels in energy production and heavy industry, provide unambiguous stratigraphic markers of the human activities that have rapidly changed planet Earth over the last century. SCPs are found in terrestrial and marine sediments or ice cores in every continent, including remote areas such as the high Arctic and Antarctica. The rapid increase in SCPs mostly occurs in the mid-twentieth century and is contemporaneous with the 'Great Acceleration'. It therefore reflects the intensification of fossil fuel usage and can be traced across the globe. We integrate global records of SCPs and propose that the global rapid increase in SCPs in sedimentary records can be used to inform a Global Standard Stratigraphic Age for the Anthropocene. A high-resolution SCP sequence from a lake or peatland may provide the much-needed 'Golden Spike' (Global Boundary Stratotype Section and Point). PMID:26020614

  2. Spheroidal carbonaceous particles are a defining stratigraphic marker for the Anthropocene

    NASA Astrophysics Data System (ADS)

    Swindles, Graeme T.; Watson, Elizabeth; Turner, T. Edward; Galloway, Jennifer M.; Hadlari, Thomas; Wheeler, Jane; Bacon, Karen L.

    2015-05-01

    There has been recent debate over stratigraphic markers used to demarcate the Anthropocene from the Holocene Epoch. However, many of the proposed markers are found only in limited areas of the world or do not reflect human impacts on the environment. Here we show that spheroidal carbonaceous particles (SCPs), a distinct form of black carbon produced from burning fossil fuels in energy production and heavy industry, provide unambiguous stratigraphic markers of the human activities that have rapidly changed planet Earth over the last century. SCPs are found in terrestrial and marine sediments or ice cores in every continent, including remote areas such as the high Arctic and Antarctica. The rapid increase in SCPs mostly occurs in the mid-twentieth century and is contemporaneous with the ‘Great Acceleration’. It therefore reflects the intensification of fossil fuel usage and can be traced across the globe. We integrate global records of SCPs and propose that the global rapid increase in SCPs in sedimentary records can be used to inform a Global Standard Stratigraphic Age for the Anthropocene. A high-resolution SCP sequence from a lake or peatland may provide the much-needed ‘Golden Spike’ (Global Boundary Stratotype Section and Point).

  3. Effects of stratigraphic heterogeneity on permeability in eolian sandstone sequence, Page sandstone, northern Arizona

    SciTech Connect

    Chandler, M.A.; Kocurek, G.; Goggin, D.J.; Lake, L.W.

    1989-05-01

    Outcrop and core data from the eolian Middle Jurassic Page Sandstone of northern Arizona show that realistic reservoir characterization can be based on the stratigraphic architecture. Outcrop displays of differential weathering, coloration, cementation, and seepage reflect stratigraphic control of fluid flow within the sandstone. Measurements of permeability using a field permeameter and conventional analysis yield a five-order-of-magnitude range of values between distinct populations. Extra-erg and/or interdune deposits are least permeable (0.67-1800 md), followed by wind-ripple strata (900-5200 md), with grain-flow strata being the most permeable (3700-12,000 md). Extra-erg and interdune deposits and some extensive bounding surfaces form significant flow barriers and tend to compartmentalize the reservoir. Reservoir characteristics of the dune cross-strata are a function of the types, distributions, and orientations of the internal stratification. Directional-flow properties within the strata are most pronounced within wind-ripple laminae. Recognition of the levels of reservoir heterogeneity is sampling-scale dependent. General models for flow within single sets of cross-strata as well as within eolian sequences can be generated based upon relative permeability between stratigraphic units. 9 figures.

  4. Architecture of delta plain deposits in a sequence stratigraphic framework: The upper carboniferous of eastern Kentucky

    SciTech Connect

    Buter, S.J. )

    1993-09-01

    Fluvio-deltaic sequences of the Upper Carboniferous Four Corners formation in the Appalachian basin of eastern Kentucky are reinterpreted using sequence stratigraphic techniques. A data set of correlated large-scale road-cut exposures and continuous coring records was processed and used in a three-dimensional (3-D) reservoir modeling program in order to obtain a detailed model of the 3-D architecture of the stratigraphic succession. The architecture of the sediment bodies is related to the position within the depositional system. The 140-m-thick Four Corners formation comprises three facies associations, which are cyclically organized. The boundaries between the cycles are formed by erosive surfaces, and are developed as lowstand incised valleys. A subsequent base-level rise resulted in the infilling of these valleys with amalgamated stacked channel deposits (early transgressive systems tract). Flood plain aggradation and extensive peat accumulation occurred during progressive rise (transgressive systems tracts). Marine flooding took place in the upper part of the sequence (late transgressive systems tract) and was followed by prograding mouthbar deposits during base-level stabilization (highstand). The sequence stratigraphic approach to these Upper Carboniferous cyclothems highlights the importance of relative sea level changes and may improve our understanding of sediment body geometries and architecture, resulting in more accurate predictive geological reservoir models of the subsurface.

  5. Offshore Investments by Colleges Draw Scrutiny

    ERIC Educational Resources Information Center

    Fain, Paul; Wolverton, Brad

    2007-01-01

    Billions of dollars in untaxed, offshore investments by college endowments could be subject to taxation under a proposal being considered by the leaders of the U.S. Senate Finance Committee. The proposed change, which targets hedge funds, a popular investing strategy for many colleges, would affect the largest college endowments, including those…

  6. Accord near for offshore California oil shipments

    SciTech Connect

    Not Available

    1993-02-15

    There are faint glimmers of hope again for offshore California operators. After more than a decade of often bitter strife over offshore oil and gas development and transportation issues, state officials and oil producers may be moving toward compromise solutions. One such solution may be forthcoming on offshore development. But the real change came with the turnabout of the California Coastal Commission (CCC), which last month approved a permit for interim tankering of crude from Point Arguello oil field in the Santa Barbara Channel to Los Angeles. The dispute over how to ship offshore California crude to market has dragged on since before Point Arguelo development plans were unveiled. The project's status has become a flashpoint in the U.S. debate over resource use and environmental concerns. The controversy flared anew in the wake of the 1989 Exxon Valdez tanker spill off Alaska, when CCC voided a Santa Barbara County permit for interim tankering, a move project operator Chevron Corp. linked to the Exxon Valdez accident. Faced with litigation, the state's economic devastation, and acrimonious debate over transporting California crude, Gov. Pete Wilson and other agencies approved the CCC permit. But there's a catch: A permanent pipeline must be built to handle full production within 3 years. The paper discusses permit concerns, the turnaround decision, the anger of environmental groups, and pipeline proposals.

  7. Cleaning the Valhall offshore oil pipeline

    SciTech Connect

    Marshall, G.R. )

    1990-08-01

    Severe wax deposits built up in the 20-in. (500-mm) Valhall subsea crude oil pipeline over a period of years. The successful program to remove these deposits gradually but completely with a series of foam and mechanical pigs is described, including details on equipment and procedures. The unique risks and difficulties associated with solids removal in offshore pipelines are discussed.

  8. 31 CFR 593.406 - Offshore transactions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Offshore transactions. 593.406 Section 593.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  9. 31 CFR 594.407 - Offshore transactions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 594.407 Section 594.407 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS...

  10. 31 CFR 594.407 - Offshore transactions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Offshore transactions. 594.407 Section 594.407 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS REGULATIONS...

  11. Fish Swimming Underwater Offshore Northern California

    USGS Multimedia Gallery

    A kelp greenling fish swimming above a seafloor of mixed gravel, cobble and rock outcrop with scattered shell. Fish is approx. 20 cm (8 inches) long. Image acquired 1 km (0.62 miles) offshore Half Moon Bay, California at a depth of 14 meters (46 ft). Also in the image are encrusting sponge...

  12. 31 CFR 593.406 - Offshore transactions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Offshore transactions. 593.406 Section 593.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  13. Solar power satellite offshore rectenna study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    It was found that an offshore rectenna is feasible and cost competitive with land rectennas but that the type of rectenna which is suitable for offshore use is quite different from that specified in the present reference system. The result is a nonground plane design which minimizes the weight and greatly reduces the number of costly support towers. This preferred design is an antenna array consisting of individually encapsulated dipoles with reflectors supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane and icing conditions for a one time cost of 5.7 billion dollars. Subsequent units would be about 1/3 less expensive. The east coast site chosen for this study represents an extreme case of severe environmental conditions. More benign and more shallow water sites would result in lower costs. Secondary uses such as mariculture appear practical with only minor impact on the rectenna design. The potential advantages of an offshore rectenna, such as no land requirements, removal of microwave radiation from populated areas and minimal impact on the local geopolitics argue strongly that further investigation of the offshore rectenna should be vigorously pursued.

  14. Human Rights, Academic Freedom, and Offshore Academics

    ERIC Educational Resources Information Center

    Ross, Andrew

    2011-01-01

    Despite the carnage wrought on higher education by the Great Recession, evidence persists that the sector is still host to a speculator psychology. One example is the unabated stampede to set up branches and programs overseas. Colleges have many reasons to go offshore: (1) to reduce costs; (2) to build their "brands" in "emerging markets"; and (3)…

  15. Planning and evaluation parameters for offshore complexes

    NASA Technical Reports Server (NTRS)

    Sincoff, M. Z. (Editor); Dajani, J. S. (Editor)

    1976-01-01

    Issues are presented for consideration in the planning and design of offshore artificial complexes. The construction of such complexes, their social, economic, and ecological impacts, and the legal-political-institutional environments within which their development could occur, are discussed. Planning, design, and construction of near-shore complexes located off the Mid-Atlantic coast of the United States is emphasized.

  16. 31 CFR 546.406 - Offshore transactions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS Interpretations ...

  17. 31 CFR 546.406 - Offshore transactions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS Interpretations ...

  18. 31 CFR 546.406 - Offshore transactions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS Interpretations ...

  19. 31 CFR 546.406 - Offshore transactions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS Interpretations ...

  20. 31 CFR 546.406 - Offshore transactions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS...

  1. Sea Stars Underwater Offshore Northern California

    USGS Multimedia Gallery

    Three sea stars on a rock, surrounded by a sandy seafloor littered with broken shells. Each sea star is approx. 10 - 15 cm (4-6 inches) across. Image acquired 4.5 km (3 miles) offshore Pigeon Point, southern San Mateo County, California at a depth of 52 meters....

  2. 31 CFR 541.406 - Offshore transactions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Offshore transactions. 541.406 Section 541.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY ZIMBABWE SANCTIONS REGULATIONS Interpretations §...

  3. Cut drydocking costs for offshore rigs

    SciTech Connect

    Albaugh, E.K.

    1985-07-01

    Heavy-lift transport vessels (HLVs) can provide an economic alternative to the conventional shipyard approach of drydocking mobile offshore rigs for regulatory body inspections and/or repairs. Contractors now can drydock rigs in areas of the world where conventional drydocks are unavailable. This article discusses pros and cons of conventional shipyard drydocking and the HLV approach.

  4. Offshore blowouts, data for risk assessment

    SciTech Connect

    Holand, P.

    1995-12-31

    Blowouts are, besides gas leakages, the major contributor to the total risk for offshore installations. Therefore, the blowout risk is always included in Quantitative Risk Analyses (QRAs) of offshore installations in the Norwegian Sector of the North Sea. SINTEF Offshore Blowout Database has existed since 1984 (until 1990 it was called Marintek`s blowout database). In 1990 the responsibility of the database was transferred to SINTEF Safety and Reliability. Throughout these years the database has been used for assessing blowout risk associated to development and operation of fields offshore Norway. Six oil companies and two consultants are presently sponsoring the database. These companies are using the database when performing risk analyses. During the past three years the database has been subjected to a thorough quality improvement, both with respect to the user interface, and most important, regarding the blowout data included in the database. What is unique with this database, besides the high quality of blowout descriptions, is first that the blowout causes are categorized related to loss of primary and secondary barriers. Secondly that the user interface makes it possible to establish searches to withdraw information regarding any blowout type subjected for specific searches.

  5. Offshore Investments by Colleges Draw Scrutiny

    ERIC Educational Resources Information Center

    Fain, Paul; Wolverton, Brad

    2007-01-01

    Billions of dollars in untaxed, offshore investments by college endowments could be subject to taxation under a proposal being considered by the leaders of the U.S. Senate Finance Committee. The proposed change, which targets hedge funds, a popular investing strategy for many colleges, would affect the largest college endowments, including those

  6. 31 CFR 543.406 - Offshore transactions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 543.406 Section 543.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY CôTE D'IVOIRE SANCTIONS...

  7. 31 CFR 543.406 - Offshore transactions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Offshore transactions. 543.406 Section 543.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY CôTE D'IVOIRE SANCTIONS REGULATIONS...

  8. CHOOSING OFFSHORE PIPELINE ROUTES: PROBLEMS AND SOLUTIONS

    EPA Science Inventory

    The report discusses the environmental and fisheries problems associated with offshore pipelines. The report focuses on how these problems can be addressed during the pipeline planning and route selection process. Geologic hazards are highlighted as the major factors related to p...

  9. Human Rights, Academic Freedom, and Offshore Academics

    ERIC Educational Resources Information Center

    Ross, Andrew

    2011-01-01

    Despite the carnage wrought on higher education by the Great Recession, evidence persists that the sector is still host to a speculator psychology. One example is the unabated stampede to set up branches and programs overseas. Colleges have many reasons to go offshore: (1) to reduce costs; (2) to build their "brands" in "emerging markets"; and (3)

  10. Solar power satellite offshore rectenna study

    NASA Astrophysics Data System (ADS)

    1980-11-01

    It was found that an offshore rectenna is feasible and cost competitive with land rectennas but that the type of rectenna which is suitable for offshore use is quite different from that specified in the present reference system. The result is a nonground plane design which minimizes the weight and greatly reduces the number of costly support towers. This preferred design is an antenna array consisting of individually encapsulated dipoles with reflectors supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane and icing conditions for a one time cost of 5.7 billion dollars. Subsequent units would be about 1/3 less expensive. The east coast site chosen for this study represents an extreme case of severe environmental conditions. More benign and more shallow water sites would result in lower costs. Secondary uses such as mariculture appear practical with only minor impact on the rectenna design. The potential advantages of an offshore rectenna, such as no land requirements, removal of microwave radiation from populated areas and minimal impact on the local geopolitics argue strongly that further investigation of the offshore rectenna should be vigorously pursued.

  11. The tectono-stratigraphic evolution of basement highs in hyper extended deep-water rifted margins : the example of the Brianonnais domain in the Alps and comparisons with modern analogues

    NASA Astrophysics Data System (ADS)

    Haupert, Isabelle; Manatschal, Gianreto; Unternehr, Patrick; Decarlis, Alessandro

    2013-04-01

    The discovery of hydrocarbon systems in hyper-extended deep-water rifted margins, in conjunction with technical developments, expanded the hydrocarbon exploration into domains that are yet little investigated. The increasing number of high-quality reflection and refraction seismic surveys and drill hole data show that deep-water rifted margins are very different from proximal rifted margins. The new data show evidence for a polyphase rift evolution resulting in complex rift architectures with variable amounts of magmatic addition and local mantle exhumation that cannot be predicted by classical rift models. Thus, understanding the thermal structure, subsidence history, depositional environment and sedimentary architecture is a prerequisite to apply the "play elements" in these yet little investigated domains, which is essential to evaluate the survivability of syn- to post-rift petroleum systems. Although a big progress was made in the understanding of deep water rifted margins in the last 5 years, there are still many fundamental questions that remain open and ask for further research on this topic. One open scientific question is related to the tectono-sedimentary evolution and subsidence history of basement highs in deep water rifted margins. Pron-Pinvidic and Manatschal (2010) showed that different types of basement highs can be distinguished in rifted margins. These highs include micro-continents, continental ribbons, H-blocks and extensional allochthons. Mapping these highs and properly define their stratigraphic and tectonic evolution provide important insights into the tectonic evolution of rifted margins. However, these blocks are often at deep-water and sealed by thick post-rift sediments. Therefore access to direct observations requires expensive drillings. An alternative way to study these blocks is to use field analogues. One of which is the Brianonnais domain in the Alps. To achieve our goal we propose to review the existing structural, stratigraphic and age data from the whole Brianonnais domain (from Liguria/Italy, across the French Alps to Grisons in Switzerland). We propose to construct key tectonic sections across the Brianonnais domain. These data will form the basis to discuss the rift-related tectono-stratigraphic and subsidence evolution and to constrain the along and across strike stratigraphic architecture of the Brianonnais. These observations will be compared with that of seismically imaged basement highs in deep-water rifted margins (e.g. outer high in Campos or Santos). In our presentation we will show results of our preliminary works on the Brianonnais domain in the French Alps and a comparisons with seismically imaged basement highs imaged offshore Newfoundland.

  12. Deep burial dolomitization driven by plate collision: Evidence from strontium-isotopes of Jurassic Arab IV dolomites from offshore Qatar

    SciTech Connect

    Vahrenkamp, V.C.; Taylor, S.R. )

    1991-03-01

    The use of strontium-isotope ratios of dolomites to constrain timing and mechanism of diagenesis has been investigated on Jurassic Arab IV dolomites from offshore Qatar. Reservoir quality is determined by two types of dolomites, which were differentiated geochemically (cathodoluminescence, fluid inclusions, and carbon and oxygen stable isotopes): (1) stratigraphically concordant sucrosic dolomites with high porosity formed during early near-surface diagenesis (Jurassic) and (2) stratigraphically discordant cylindrical bodies of massive, porosity-destroying dolomites formed late during deep burial diagenesis (Eocene-Pliocene). Detailed Sr-isotope analysis of dolomites from the Arab IV confirms an Early Jurassic age of the sucrosic, high porosity dolomites ({sup 87}Sr/{sup 86}SR = 0.70707 for NBS 987 = 0.71024) with magnesium and strontium being derived from Jurassic seawater. Late Tertiary compressional orogeny of the Zagros belt to the north is proposed to have caused large-scale squeezing of fluids from the pore system of sedimentary rocks. A regional deep fluid flow system developed dissolving infra-Cambrian evaporites upflow and causing large-scale deep burial dolomitization downflow.

  13. Seismic expression of depositional systems tracts and application to hydrocarbon exploration in Bredasdorp basin, offshore South Africa

    SciTech Connect

    Beamish, G.W.J.

    1989-03-01

    Postrift Cretaceous sequences of Bredasdorp basin, offshore South Africa, were rigorously analyzed using the unified application of the latest seismic-stratigraphic, sequence-stratigraphic, and depositional systems concepts. Using 101 seismic profiles totaling 5600 km, the authors identified ten cyclic depositional sequences bounded by nine type 1 and two type 2 unconformities. Component depositional systems tracts exhibit a distinct seismic expression and can be delineated using truncation and lap-out relationships. Lowstand systems tracts developed on type 1 unconformities, which resulted from relative sea level fall below the shelf edge. In a terrigenous clastic basin such as Bredasdorp, these tracts are interpreted as being composed of basin-floor turbidite fans, channels, and/or sheets. These features formed contemporaneously with the erosion of incised valleys and submarine canyons, followed by channelized slope fans and deltaic/coastal lowstand wedges that prograded during a relative sea level rise. Subsequent flooding of the shelf as relative sea level rise accelerated resulted in poorly defined transgressive systems tracts. With the relative sea level at a highstand, extensively developed deltaic/coastal systems prograded basinward exhibiting well-defined clinoforms. The major hydrocarbon plays in the lowstand tracts occur as mounded basin-floor turbidite fans, channel fills, and draped sheets and are found in the updip pinch-out of deltaic/coastal sandstones.

  14. Combined effect of tectonism, eustasy, and sediment supply on the depositional-sequence history of the western offshore, South Africa

    SciTech Connect

    Jungslager, E.H.A. )

    1991-03-01

    Interpreted seismic profiles and maps of depositional systems tracts highlight variations in basin-fill architecture and their inferred causes along western offshore South Africa. Sequence-stratigraphic concepts developed by Exxon were used to interpret 10,000 km of seismic data and logs from 31 exploration boreholes within an area of 90,000 km{sup 2}. Lower frequency second-order supercycles (5-10 Ma) are attributed to changes in the rate of subsidence and are expressed either by predominantly progradational or aggradational depositional supersequence. In addition to these long-duration, basin-wide stratigraphic packages, component depositional sequences that formed in response to third order (1-5 Ma) and higher frequency cycles vary with structural setting within the depobasin, namely depocenter, basin flanks, shelf-edge, and slope systems. High-order sequences are attributed to eustatically driven, high-frequency, base-level changes and/or localized tectonic events (i.e. slope failure, gravity faulting). Variations in the areal distribution of lowstand and shelf-margin systems tracts document lateral shifting sediment supplies and the presence of entrenched feeder-canyons linked to incised valley systems on the shelf. Many canyons, however, terminate updip and may be related to slope failure and headward erosion. The tentative correlation of regionally developed unconformities of the west coast based on microfaunal dating of a limited number of marine condensed sections points to a remarkable correspondence with the Exxon global sea-level chart.

  15. Glaciotectonic deformation and reinterpretation of the Worth Point stratigraphic sequence: Banks Island, NT, Canada

    NASA Astrophysics Data System (ADS)

    Vaughan, Jessica M.; England, John H.; Evans, David J. A.

    2014-05-01

    Hill-hole pairs, comprising an ice-pushed hill and associated source depression, cluster in a belt along the west coast of Banks Island, NT. Ongoing coastal erosion at Worth Point, southwest Banks Island, has exposed a section (6 km long and 30 m high) through an ice-pushed hill that was transported 2 km from a corresponding source depression to the southeast. The exposed stratigraphic sequence is polydeformed and comprises folded and faulted rafts of Early Cretaceous and Late Tertiary bedrock, a prominent organic raft, Quaternary glacial sediments, and buried glacial ice. Three distinct structural domains can be identified within the stratigraphic sequence that represent proximal to distal deformation in an ice-marginal setting. Complex thrust sequences, interfering fold-sets, brecciated bedrock and widespread shear structures superimposed on this ice-marginally deformed sequence record subsequent deformation in a subglacial shear zone. Analysis of cross-cutting relationships within the stratigraphic sequence combined with OSL dating indicate that the Worth Point hill-hole pair was deformed during two separate glaciotectonic events. Firstly, ice sheet advance constructed the hill-hole pair and glaciotectonized the strata ice-marginally, producing a proximal to distal deformation sequence. A glacioisostatically forced marine transgression resulted in extensive reworking of the strata and the deposition of a glaciomarine diamict. A readvance during this initial stage redeformed the strata in a subglacial shear zone, overprinting complex deformation structures and depositing a glaciotectonite 20 m thick. Outwash channels that incise the subglacially deformed strata record a deglacial marine regression, whereas aggradation of glaciofluvial sand and gravel infilling the channels record a subsequent marine transgression. Secondly, a later, largely non-erosive ice margin overrode Worth Point, deforming only the most surficial units in the section and depositing a capping till. The investigation of the Worth Point stratigraphic sequence provides the first detailed description of the internal architecture of a polydeformed hill-hole pair, and as such provides an insight into the formation and evolution of an enigmatic landform. Notably, the stratigraphic sequence documents ice-marginal and subglacial glaciotectonics in permafrost terrain, as well as regional glacial and relative sea level histories. The reinterpreted stratigraphy fundamentally rejects the long-established paleoenvironmental history of Worth Point that assumed a simple layer-cake stratigraphy including the type-site for an organically rich, preglacial interval (Worth Point Fm).

  16. Preliminary stratigraphic and paleomagnetic results from Neogene basins across the Anatolian Plateau (Turkey).

    NASA Astrophysics Data System (ADS)

    Lucifora, Stella; Cifelli, Francesca; Mazzini, Ilaria; Cosentino, Domenico; Mattei, Massimo; Cipollari, Paola; Gliozzi, Elsa; Palolo Cavinato, Gian

    2010-05-01

    An integrated paleomagnetic and stratigraphic study on Neogene basins across the Anatolian Plateau was carried out. This study is developed within the VAMP (Vertical Anatolian Movement Project), an interdisciplinary project aimed to the recent tectonic evolution of the central Anatolian Plateau. The studied areas are located in southern Turkey (Adana, Mut and Ermenek basins) and in northern Turkey (Kazan, Çankiri, Kastamonu, Boyabat and Sinop basins). For paleomagnetic analyses we sampled 1062 standard cylindrical samples from 13 stratigraphic sections, and 746 samples for paleontological analysis were taken from the same sections. AMS (Anisotropy of Magnetic Susceptibility), magnetic mineralogy and paleomagnetic polarity data are presented together with the results of the integrated stratigraphic analyses. In the Southern Turkey basins preliminary results show the diffuse presence of authigenic iron sulphides, together with magnetite, as main magnetic carriers. In these sections the iron-sulphides Characteristic Natural Magnetization (ChRM) component is characterized by inconsistent polarity record, suggesting that iron-sulphides have a late diagenetic origin. Conversely, magnetite bearing sediments show more reliable results in term of magnetic polarity interpretations. Preliminary stratigraphic and paleomagnetic results from the southern margin of the plateau allow us both to refine the stratigraphy for the late Miocene of the Adana Basin and to better constrain the age of the youngest marine deposits of the Mut and Ermenek basins. In the late Miocene of the Adana Basin evidence of the Messinian salinity crisis led to a new stratigraphic framework specially for the Messinian-Pliocene interval. Thick fluvial conglomerates from the uppermost Messinian deposits of the Adana Basin, which could be linked to the activation of the southern margin of the plateau, allow us to constrain at about 5.4 Ma the uplift of the central Anatolian Plateau. On the other hand, the preliminary results of the micropaleontological analyses carried out on the higher marine deposits sampled in the northern part of the Ermenek Basin (Basyayla section, 1840 m a.s.l.) point to a post-Tortonian age for the plateau uplift. The age of the basins at the northern margin of the plateau are very poor constrained, except for that basins containing vertebrate-bearing continental deposits. However, from a palaeogeographic point of view, our preliminary data suggest a possible Tortonian connection between the Çankiri Basin and the Paratethyan realm. This presentation was supported by the EUROCORE programme TOPO-EUROPE of the European Science Foundation.

  17. Mapping Seabird Sensitivity to Offshore Wind Farms

    PubMed Central

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N.; Caldow, Richard W. G.; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979–2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km×3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species’ ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented. PMID:25210739

  18. Mapping seabird sensitivity to offshore wind farms.

    PubMed

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N; Caldow, Richard W G; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979-2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species' ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented. PMID:25210739

  19. Morpho-bathymetric and seismic-stratigraphic investigation in the Messina Straits (Southern Italy). The search for geomorphic and stratigraphic evidence of shallow seismogenic faults

    NASA Astrophysics Data System (ADS)

    Ridente, Domenico; Latino Chiocci, Francesco; Martorelli, Eleonora; Sposato, Andrea; Krastel, Sebastian; Gross, Felix; Lili, Fu; Schulten, Irena

    2013-04-01

    The 28 December, 1908 Reggio Calabria and Messina earthquake was one of the strongest (Mw 7.1) ever occurred in Italy, and was also followed by a tsunami that severely impacted the coasts of the Messina Straits. Although most workers agree that its epicentre locates in the Messina Straits, the source fault has never been detected; a century long question is therefore pending on the source of both the 1908 earthquake and tsunami. Within the ongoing debate on this question, little attention has been given, in recent time, to insights from very high resolution morpho-bathymetric data, particularly as regarding the question on whether a submarine landslides may had been the cause of the tsunami. We aim at filling this gap by presenting the results of a detailed geomorphic analysis in the area of the Messina Straits, integrated with high-resolution MC seismic profiles recently acquired during Cruise M86/2 on board R/V Meteor. The primary morpho-structural feature in this area is the axial channel of the Messina Canyon, toward which inflow several tributary canyons that incise the steep continental slope on the Calabrian and Sicilian margins. These canyons deeply cut into a very narrow continental shelf and merge laterally forming a continuous erosional margin rimming the Messina Straits. This giant, composite canyon environment is the locus of intense erosional and mass failure processes that superimpose on active tectonic deformation, resulting in a complex geomorphology that hinders the distinction between tectonic and sedimentary features. Based on detailed morpho-bathymetric and seismic-stratigraphic analysis, we discuss on the evidence of possible geomorphic and stratigraphic expression of tectonic deformation compatible with the 1908 Mw 7.1 earthquake.

  20. Sedimentological indicators of paleoenvironments and siliciclastic stratigraphic sequences in some Miocene deposits of the Calvert Cliffs, southern Maryland

    USGS Publications Warehouse

    Shideler, G.L.

    1994-01-01

    Middle Miocene siliciclastic deposits comprising the Calvert Cliffs section at the Baltimore Gas and Electric Company's (BG&E) nuclear power plant site in southern Maryland were analyzed in terms of lithostratigraphy, sedimentary structures, and granulometric parameters, to interprete paleo-environments within a sequence-stratigraphic framework. In terms of sequence-stratigraphic models, the BG&E section can be interpreted as consisting of two genetic stratigraphic sequences (Galloway model), namely, a shelf sequence and an overlying deltaic sequence. Using the Exxon model, the section consists of two third-order (1-5 m.y. duration) depositional sequences. The stratigraphic sequences of the BG&E section reflect both relatively short-term eustatic transgressive events, as well as a long-term regressive trend with associated local deltation and coastal progradation. The regression probably signified a regional basinward shift of depocenters within the Salisbury embayment during Miocene time. -from Author

  1. Improving coastal wave hindcasts by combining offshore buoy observations with global wave models.

    NASA Astrophysics Data System (ADS)

    Crosby, S. C.; O'Reilly, W. C.; Guza, R. T.

    2014-12-01

    Waves conditions in southern California are sensitive to offshore wave directions. Due to blocking by coastal islands and refraction across complex bathymetry, a <10o difference in incident wave direction can dramatically change coastal wave energy. Directional wave buoys are fundamentally low-resolution instruments, while the directional bin widths of operational wind-wave models are coarse (e.g. 10o). Operational wind-wave models have useful prediction skill in the nearshore, however, wave buoy measurements, when combined with standard directional estimation techniques, are shown to provide significantly better hindcasts. Techniques to combine offshore global wave model predictions (NOAA's Wave Watch 3 hindcasts) and offshore buoy measurements are being developed. The skill of different combination methodologies as an offshore boundary condition is assessed using spectral ray-tracing methods to transform incident offshore swell-spectra to shallow water buoy locations. A nearly continuous 10 yr data set of approximately 14 buoys is used. Comparisons include standard bulk parameters (e.g. significant wave height, peak period), the frequency-dependent energy spectrum (needed for run-up estimation) and radiation stress component Sxy (needed for alongshore current and sediment transport estimation). Global wave model uncertainties are unknown, complicating the formulation of optimum assimilation constraints. Several plausible models for estimating offshore waves are tested. Future work includes assimilating nearshore buoy observations, with the long-term objective of accurate regional wave hindcasts using an efficient mix of global wave models and buoys. This work is supported by the California Department of Parks and Recreation, Division of Boating and Waterways Oceanography Program.

  2. Characterizing Offshore Earthquakes at Hawaii Recorded by the First PLUME Temporary Ocean-Bottom Seismometer Network

    NASA Astrophysics Data System (ADS)

    Anchieta, M. C.; Wolfe, C. J.; Laske, G.; Collins, J. A.; Solomon, S. C.; Detrick, R. S.; Orcutt, J. A.; Bercovici, D. A.; Hauri, E. H.; Pavlis, G. L.; Eakins, J. A.; Vernon, F. L.

    2007-12-01

    In 2005-2006 and again in 2006-2007, the Plume-Lithosphere Undersea Melt Experiment (PLUME) deployed successive networks of ocean-bottom seismometers (OBSs) around the Hawaiian Islands. The experiment consisted of a 2-year deployment of broadband land seismometers and two year-long deployments of broadband OBSs, the first with a station spacing of about 75 km centered on the island of Hawaii and the second with larger spacing of about 200 km. PLUME's major objective was to determine the mantle structure beneath the Hawaiian hotspot and swell; however, these unique data are also potentially valuable to the study of small offshore earthquakes. The Hawaiian Islands are marked by significant and continuous seismic activity. In addition to the thousands of microearthquakes that are detected and located by the USGS Hawaiian Volcano Observatory (HVO) seismic network each year, Hawaii also experiences occasional large, damaging earthquakes. Several of these large events occurred in Hawaii's offshore region (e.g., the 1871 Lanai earthquake, the 1938 Maui earthquake, and the 2006 Kiholo Bay earthquake), and such events pose a significant seismic hazard for the state. We assess whether data from the first PLUME OBS deployment and land data can improve the detection and location of offshore microearthquakes around Hawaii. We are particularly interested in whether the PLUME data set may reveal offshore fault zones not detected to date by the HVO seismic network. Initial tests indicate that many offshore earthquakes already in the HVO catalog produce detectable P and S waves on the PLUME three- component seismometers, and earthquake detection rates are improved when seismograms are high-pass filtered above about 5 Hz to reduce the seismic noise from wind-generated waves. Differential pressure gauge data yield far fewer detectable events (with the exception of a swarm of Loihi earthquakes in December 2005) and appear less promising for improving our knowledge of offshore seismicity patterns.

  3. Effects of Second-Order Hydrodynamics on a Semisubmersible Floating Offshore Wind Turbine: Preprint

    SciTech Connect

    Bayati, I.; Jonkman, J.; Robertson, A.; Platt, A.

    2014-07-01

    The objective of this paper is to assess the second-order hydrodynamic effects on a semisubmersible floating offshore wind turbine. Second-order hydrodynamics induce loads and motions at the sum- and difference-frequencies of the incident waves. These effects have often been ignored in offshore wind analysis, under the assumption that they are significantly smaller than first-order effects. The sum- and difference-frequency loads can, however, excite eigenfrequencies of the system, leading to large oscillations that strain the mooring system or vibrations that cause fatigue damage to the structure. Observations of supposed second-order responses in wave-tank tests performed by the DeepCwind consortium at the MARIN offshore basin suggest that these effects might be more important than originally expected. These observations inspired interest in investigating how second-order excitation affects floating offshore wind turbines and whether second-order hydrodynamics should be included in offshore wind simulation tools like FAST in the future. In this work, the effects of second-order hydrodynamics on a floating semisubmersible offshore wind turbine are investigated. Because FAST is currently unable to account for second-order effects, a method to assess these effects was applied in which linearized properties of the floating wind system derived from FAST (including the 6x6 mass and stiffness matrices) are used by WAMIT to solve the first- and second-order hydrodynamics problems in the frequency domain. The method has been applied to the OC4-DeepCwind semisubmersible platform, supporting the NREL 5-MW baseline wind turbine. The loads and response of the system due to the second-order hydrodynamics are analysed and compared to first-order hydrodynamic loads and induced motions in the frequency domain. Further, the second-order loads and induced response data are compared to the loads and motions induced by aerodynamic loading as solved by FAST.

  4. UV light process cleans water from offshore UK gas field

    SciTech Connect

    1996-02-01

    British Gas has developed and installed on onshore treatment plant at Easington on the East Coast of England to process produced water from Amethyst natural gas field located some 20 miles offshore. The new system uses the ultraviolet/ozone (UV/Ozone) process, as described here. Test-rig studies demonstrate the process for other production chemicals and naturally occurring substances that may be subject to discharge constraints in environmentally sensitive areas. For example, the process has removed mono- and poly-aromatic hydrocarbons to low levels. Further work at test-rig and pilot-plant scale will permit the process to be extended to other contaminated waters, both from natural gas production and contaminated inland sites, and will ensure that economic, integrated treatment schemes are in place when needed by British Gas.

  5. Divergent evolutionary processes associated with colonization of offshore islands.

    PubMed

    Martínková, Natália; Barnett, Ross; Cucchi, Thomas; Struchen, Rahel; Pascal, Marine; Pascal, Michel; Fischer, Martin C; Higham, Thomas; Brace, Selina; Ho, Simon Y W; Quéré, Jean-Pierre; O'Higgins, Paul; Excoffier, Laurent; Heckel, Gerald; Hoelzel, A Rus; Dobney, Keith M; Searle, Jeremy B

    2013-10-01

    Oceanic islands have been a test ground for evolutionary theory, but here, we focus on the possibilities for evolutionary study created by offshore islands. These can be colonized through various means and by a wide range of species, including those with low dispersal capabilities. We use morphology, modern and ancient sequences of cytochrome b (cytb) and microsatellite genotypes to examine colonization history and evolutionary change associated with occupation of the Orkney archipelago by the common vole (Microtus arvalis), a species found in continental Europe but not in Britain. Among possible colonization scenarios, our results are most consistent with human introduction at least 5100 bp (confirmed by radiocarbon dating). We used approximate Bayesian computation of population history to infer the coast of Belgium as the possible source and estimated the evolutionary timescale using a Bayesian coalescent approach. We showed substantial morphological divergence of the island populations, including a size increase presumably driven by selection and reduced microsatellite variation likely reflecting founder events and genetic drift. More surprisingly, our results suggest that a recent and widespread cytb replacement event in the continental source area purged cytb variation there, whereas the ancestral diversity is largely retained in the colonized islands as a genetic 'ark'. The replacement event in the continental M. arvalis was probably triggered by anthropogenic causes (land-use change). Our studies illustrate that small offshore islands can act as field laboratories for studying various evolutionary processes over relatively short timescales, informing about the mainland source area as well as the island. PMID:23998800

  6. SKS Splitting from Ocean Bottom Seismometer Data Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Ramsay, J.; Kohler, M. D.; Davis, P. M.; Weeraratne, D. S.

    2014-12-01

    SKS arrivals from ocean bottom seismometer (OBS) data of the ALBACOREexperiment offshore Southern California are analyzed for shear wave splitting. The ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) project involved deployment of 34 OBSs for 12 months in a region extending up to 500 kilometers west onto the oceanic Pacific plate. Splitting fast directions are similar to on-land directions, WSW-ENE, and exhibit similar delays, 1.1-1.4 seconds. A numerical method to remove S-wave interference with SKKS arrivals by f-k velocity filtering is tested with synthetic and the observed OBS data. The fast directions are at 45 degrees to the direction of absolute plate motion (APM) of the Pacific plate suggesting that either frozen-in anisotropy from paleo-spreading dominates over APM effects in the asthenosphere or that deeper mantle shearing has occurred unrelated to APM. A toroidal flow around slab rollback would be consistent with the splitting results if the slab rollback resulted in large-scale secondary flow well into Pacific plate, or if the source of the splitting extended much deeper than 200 km.

  7. Post-glacial sea-level history for SW Ireland (Bantry Bay) based on offshore evidence

    NASA Astrophysics Data System (ADS)

    Plets, R. M.; Callard, L.; Cooper, A.; Long, A. J.; Belknap, D. F.; Edwards, R.; Jackson, D.; Kelley, J. T.; Long, D.; Milne, G. A.; Monteys, X.; Quinn, R.

    2013-12-01

    In recent years, progress in remote sensing techniques has helped to constrain the advance and retreat phases of the British-Irish Ice Sheet during and after the Last Glacial Maximum (LGM), both on- and offshore. However, little evidence has been collected to study the pattern of relative sea-level (RSL) change immediately after ice sheet retreat. Glacio-isostatic adjustment (GIA) models suggest a complex RSL pattern around Ireland, influenced by local and regional isostatic movements. Unfortunately, such models are poorly constrained for periods during which RSL was significantly lower than present, particularly the Late Pleistocene and Early Holocene, owing to the paucity of accurate observational data offshore. This poster presents post-LGM stratigraphic evidence from Bantry Bay (SW Ireland), one of seven areas targeted around the Irish Sea as part of a larger NERC funded project which aims to provide the first field data on the depth and age of the RSL minimum since deglaciation in the Irish Sea Basin. Data examined consists of: multibeam bathymetry and backscatter, pinger sub-bottom and vibrocores (25 sites). Notable features on the multibeam are a bluff line in the outer bay with a maximum height of 10 m in water depths of c. -80 m which forms the western edge of a large sediment lobe. The south-western boundary of this lobe is marked by a series of long (up to 22 km), parallel ridges at depths between -96 m and -131 m, with iceberg scouring evident on the offshore margin. Six seismo-stratigraphic units are interpreted from the pinger data, the most prominent of which can be traced from the inner part of the Bay to the inshore edge of the ridges. This unit sits on an erosional surface, is characterised by a turbid acoustic signature and is identified as alternating sand and clay layers with some traces of organic material and gas. Equal amounts of marine and estuarine foraminifera are present within this unit, whilst the underlying unit has a higher percentage of brackish species and the overlying unit becomes predominantly marine. Based on this evidence, we suggest that the erosional surface represents the transgressive surface, underlying intertidal sediments. Mapping the extent of this surface reveals a maximum depth of -75 m offshore, rising gradually to a depth of -30 m in the inner Bay, a profile remarkably similar to the modelled sea-level curve for the area. The long parallel ridges are interpreted to represent ice-marginal, submarine moraine ridges associated with ice retreat, behind which a glacio-marine delta formed, resulting in the large sediment lobe imaged at the mouth of Bantry Bay. Foraminifera from the proposed transgressive surface have been submitted for radiocarbon dating. Once available, these results will be used for fine-tuning the Earth and ice model parameters in the GIA model. Such adjustments could have important implications for modelled RSL curves around the Irish Sea basin.

  8. Rupture lengths and temporal history of significant earthquakes on the offshore and north coast segments of the Northern San Andreas Fault based on turbidite stratigraphy

    NASA Astrophysics Data System (ADS)

    Goldfinger, Chris; Morey, Ann E.; Nelson, C. Hans; Gutiérrez-Pastor, Julia; Johnson, Joel E.; Karabanov, Eugene; Chaytor, Jason; Eriksson, Andrew; Shipboard Scientific Party

    2007-02-01

    74 piston, gravity and jumbo Kasten cores were collected from channel and canyon systems draining the northern California continental margin to investigate the record of periodic Holocene turbidites for possible connection to large magnitude earthquakes on the adjacent Northern San Andreas Fault. Poorly known channel systems were mapped with multibeam sonar to define pathways and channel confluences. Cores sampled all major and many minor channel systems extending from Cape Mendocino to just north of Monterey Bay. Sampling both along and across channels was done and particular attention was paid to channel confluences, as these areas afford opportunities to test for synchronous triggering of turbidity currents. While at sea, all cores were scanned using a GEOTEK multisensor core logger (MSCL), which collects high-resolution photography, P-wave velocity, gamma-ray density, and magnetic susceptibility data from the unsplit cores. Lithology was logged visually, and cores were later imaged with X-radiography. We use 14C ages, relative dating tests at channel confluences, and stratigraphic correlation using physical properties to determine whether turbidites deposited in separate channel systems are correlative, implying they were triggered by a common event. These tests can, in most cases, separate earthquake-triggered turbidity currents from other possible sources. The late Holocene turbidite record off northern California passes these tests for synchronous triggering, and can be correlated with multiple proxies from site to site between Noyo Channel and the latitude of San Francisco. Preliminary comparisons of our event ages with existing and in progress work at onshore coastal sites show good correlation, further circumstantial evidence that the offshore record is primarily earthquake generated. During the last ˜ 2800 yr, 15 turbidites are recognized, including the great 1906 earthquake. Their chronology establishes an average repeat time of ˜ 200 yr, similar to the onshore value of ˜ 230 yr. Along-strike correlation suggests that at least 8 of the youngest 10 of these events ruptured the 320 km distance from the Mendocino Triple Junction to near San Francisco.

  9. Eolian Dune, interdune, sand sheet, and Siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran Area, Saudi Arabia

    SciTech Connect

    Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

    1983-02-01

    An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks, sources, (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

  10. Eolian dune, interdune, sand sheet, and siliciclastic Sabkha sediments of an offshore prograding Sand Sea, Dhahran area, Saudi Arabia

    SciTech Connect

    Fryberger, S.G.; Al-Sari, A.M.; Clisham, T.J.

    1983-02-01

    An offshore prograding sand sea exists along portions of the Arabian Gulf coastline near Dhahran, Saudi Arabia. In this region, sediments of eolian dune, interdune, sand sheet, and siliciclastic sabkha intercalate with marine deposits. This depositional setting is characterized by strong offshore winds which supply abundant sand to the coastline, and cause at present time the outbuilding of the dune system. This quartz-detrital dominant setting contrasts markedly with the carbonate dominant setting resulting from onshore winds in the Trucial Coast area to the south. The broad intercalation of eolian and marine deposits which results creates ideal potential for subregional stratigraphic petroleum traps, due to pinch-out of porous and permeable dune sands into impermeable marine mudstones. Within the eolian system itself are potential reservoir rocks (dunes), sources (organic-rich sabkha and interdune deposits), and seals (zones of early cementation in all deposits). Early cementation is very common in all facies of the eolian sand sea. The early cementation occurs owing to (1) soil formation, (2) deposition of pore-filling gypsiferous cements from saturated solutions near water table, and (3) addition of sand-size windblown evaporitic material to sands downwind of sabkhas.

  11. The offshore record of variable Cenozoic sediment flux from Western Scandinavia

    NASA Astrophysics Data System (ADS)

    Goledowski, B.; Nielsen, S. B.; Calusen, O. R.

    2009-04-01

    The rates of sediment input to the North Sea and the Norwegian Shelf varied significantly during the Cenozoic. During Paleocene and Eocene times The Shetland Platform and Scottish Highlands were the main sediment sources, while with the onset of the Oligocene more sediment was coming from the Scandinavian shield (Millennium Atlas). In general, the western Scandinavian sediment production rate increased from south to north, with more than 500m of Oligocene deposits in the central and eastern North Sea (Huuse et al., 2001) to as much as 2000m of Pliocene deposits in the Mre basin (Dehls et al., 2002). This is believed mainly to be a consequence of varying erosion rates and/or changes in sediment catchments in Western Scandinavia. This has previously been interpreted in terms of variable tectonic uplift of the area caused by a hitherto unknown tectonic agent; Neither crustal shortening and thickening or magmatic underplating onshore, as well as other plate tectonic mechanisms, are compatible with observations. A dense grid of seismic data and well logs from numerous boreholes in the research area allow to estimate the rate of deposition of matrix mass and to localize main areas of sediment outpour as a function of time. Here we present semi-quantitative maps of sediment flux from western Scandinavia during subsequent epochs of the Cenozoic and discuss possible explanations. After a warm and ice-free Cretaceous period, the climate remained mild during Paleocene and Eocene times. On the Eocene-Oligocene greenhouse-icehouse transition the sediment yield of the Scandinavian shield increased. Furthermore, recent results (Heilmann-Clausen and van Simayes, 2005; Nielsen et al., 2008; Sliwinska et al., 2008) show a correlation between climate fluctuations and sequence stratigraphic surfaces and lithological changes in the North Sea. Based on this evidence we suggest that a rapid cooling at the beginning of Oligocene (Oi-1 glaciation, Zachos et al., 2001) changed the erosional regime in western Scandianvia from fluvial (which is inefficient in tectonically stable settings, regardless of the amount of precipitation - Von Blanckenburg, 2005) to glacial. As, furthermore, glacial erosion (the glacial "buzzsaw" Mitchell and Montgomery, 2006; Brozovic et al., 1997; Pedersen et al, 2008) and periglacial processes (Anderson, 2002) are known to possess the potential for producing characteristic low-relief accordant landscapes at high elevation, this hypothesis also provides and alternative to understanding flattish landscape elements in the western Scandinavian highlands, which conventionally have been explained as remnants of uplifted peneplains previously graded to sea level (the Davisian cyclic landscape evolution model). Therefore, given the Eocene-Oligocene greenhouse-icehouse transition, which must have increased the importance of glacial and periglacial erosion and transport processes in the highlands of western Scandinavia, a hypothesis of climate control on erosional and depositional history of western Scandinavia and adjacent sedimentary basins emerges. This hypothesis is to be tested using the present results. Estimation of offshore matrix mass will be the basis for reconstruction of the development of source areas with use of mathematical models of landscape evolution.

  12. Bedout basement rise, offshore northwestern Australia: evidence of an unshocked mafic volcanic hyaloclastite volcanic breccia

    NASA Astrophysics Data System (ADS)

    Glikson, A.

    2004-12-01

    Core samples from Bedout-1 (3035.8-3044.95 m.), Bedout basement rise, offshore northwestern Australia, were examined by optical microscopy, SEM, EDS and WDS spectrometry. At this stratigraphic depth level Becker et al. (2004) interpret cryptocrystalline alteration zones around and within plagioclase in terms of shock-induced transformation of feldspar into diaplectic maskelynite glass _u postulating a ~200 km-large impact structure and thereby an impact connection of the Permian-Triassic boundary mass extinction. However, the breccia is dominated by fragments of microlitic basalt and ophitic-textured dolerite with well preserved igneous textures, showing no evidence of shock metamorphism. Euhedral pseudomorphs of chlorite and amphibole, probably after pyroxene, protrude into or are enveloped by euhedral albite-twinned calcic plagioclase (andesine to bytownite). Minor phases include euhedral ilmenite needles and subhedral magnetite grains. Plagioclase is altered by cryptocrystalline albite and microcrystalline albite-chlorite matrix along crystal boundaries, along twin lamella and within internal oscillatory crystal zones, consistent with burial metamorphosed hydrovolcanic basalts and spilites (e.g. Amstutz, 1974). The volcanic fragments are set within, and injected by, microcrystalline intergranular mesostasis of mixed mineral fragments and volcanic meta-glass. Becker et al. (2004) refer to the breccia in part as product of Mg-rich sediments (e.g. dolomites). However, apart from the pristine igneous textures of the breccia, the transition element levels (chlorite in dolerite fragment "C Ni 97-160 ppm; Co 75-152 ppm; Cu 69-204 ppm; mesostasis "C Ni 29-45 ppm; Co 18-52 ppm; Cu 26-110 ppm) are consistent with Fe-rich basalts but exceed common abundances in carbonates and marls (BVTP, 1981; Wedepohl, 1978). No shock metamorphic features, such as planar deformation features (PDF), are observed in the feldspar or in any other phases. No criteria for discriminating maskelynite and volcanic meta-glass are indicated by Becker et al. (2004). As PDF formation (10-35 GPa) necessarily precedes diaplectic transformation into maskelynite (35-45 GPa) (French, 1998), a presence of maskelynite is inconsistent with the absence of PDF in the plagioclase _u a phase prone to the development of shock effects (e.g. Mory, 2000). Little evidence exists for the hydrothermal activity which typically follows impact events. However, thanks to a partial development of a rim syncline-like structure in Triassic sediments around the Bedout rise, further testing of the origin of this remarkable structure is warranted. Amstutz, G.C., 1974, Spilites and Spilitic Rocks, Springer-Verlag, Berlin; Becker, L. et al., 2004, Science Express, 13.5.04; BVSP - Basaltic Volcanism Study Project, 1981, Pergamon; French, B.M., 1998, Traces of Catastrophe, Lunar and Planetary Contributions 954; Mory et al., 2000, Earth and Planetary Science, 177, 119-128; Wedepohl, K.H., Handbook of Geochemistry, Springer-Verlag, 1978.

  13. Design verification of offshore concrete structures

    SciTech Connect

    Waagaard, K.

    1993-12-31

    Offshore concrete structures are today designed using the best available techniques. These include predictions of the force resultants in the structure using FE analysis with up to 1.5 million degrees of freedom, code checking of FE results using special dedicated post-processing software, local capacity evaluations in areas where the linear FE analysis is known to be inaccurate. Further, special analyses are carried out for prediction of response from earthquake, wave induced dynamic action and geometric non-linear action. Verification of the design of offshore concrete structures are today carried out either as a document review of original design work, by independent design analysis and code checking or a combination of above. This paper will, based on current status, evaluate the situation and discuss a verification approach which may be used for both shallow and deep water structures.

  14. Offshore technology has a tremendous future

    SciTech Connect

    Brundage, H.T.

    1984-05-01

    Proven offshore technology has the capability to produce oil and gas through the world's continental shelves, on the continental slopes, and toward the abyssal plains. As with all other economic endeavors, there will eventually be a point of diminishing returns in producing offshore hydrocarbons. But just where or when this point will be reached is not now known, nor is it likely to be known soon. A basic fact of oceanographic research is that oil shows have been found in deep ocean basins, such as at Challenger Knoll in the Sigsbee Deep in the central Gulf of Mexico, and elsewhere. At least 240 billion barrels of recoverable oil are considered to exist in the world's continental shelves. Exploratory drilling combined with engineering and oceanographic research, continually broaden horizons and potential in this respect.

  15. Perspectives of offshore geothermal energy in Italy

    NASA Astrophysics Data System (ADS)

    Armani, F. B.; Paltrinieri, D.

    2013-06-01

    Italy is the first European and world's fifth largest producer of geothermal energy for power generation which actually accounts for less than 2% of the total electricity production of the country. In this paper after a brief introduction to the basic elements of high-enthalpy geothermal systems, we discuss the potentialities represented by the submarine volcanoes of the South Tyrrhenian Sea. In particular we focus on Marsili Seamount which, according to the literature data, can be considered as a possible first offshore geothermal field; then we give a summary of the related exploitation pilot project that may lead to the realization of a 200MWe prototype power plant. Finally we discuss some economic aspects and the development perspectives of the offshore geothermal resource taking into account the Italian energy framework and Europe 2020 renewable energy target.

  16. Structural and Sequence Stratigraphic Analysis of the Onshore Nile Delta, Egypt.

    NASA Astrophysics Data System (ADS)

    Barakat, Moataz; Dominik, Wilhelm

    2010-05-01

    The Nile Delta is considered the earliest known delta in the world. It was already described by Herodotus in the 5th Century AC. Nowadays; the Nile Delta is an emerging giant gas province in the Middle East with proven gas reserves which have more than doubled in size in the last years. The Nile Delta basin contains a thick sedimentary sequence inferred to extend from Jurassic to recent time. Structural styles and depositional environments varied during this period. Facies architecture and sequence stratigraphy of the Nile Delta are resolved using seismic stratigraphy based on (2D seismic lines) including synthetic seismograms and tying in well log data. Synthetic seismograms were constructed using sonic and density logs. The combination of structural interpretation and sequence stratigraphy of the development of the basin was resolved. Seven chrono-stratigraphic boundaries have been identified and correlated on seismic and well log data. Several unconformity boundaries also identified on seismic lines range from angular to disconformity type. Furthermore, time structure maps, velocity maps, depth structure maps as well as Isopach maps were constructed using seismic lines and log data. Several structural features were identified: normal faults, growth faults, listric faults, secondary antithetic faults and large rotated fault blocks of manly Miocene age. In some cases minor rollover structures could be identified. Sedimentary features such as paleo-channels were distinctively recognized. Typical Sequence stratigraphic features such as incised valley, clinoforms, topsets, offlaps and onlaps are identified and traced on the seismic lines allowing a good insight into sequence stratigraphic history of the Nile Delta most especially in the Miocene to Pliocene clastic sedimentary succession.

  17. Genetic stratigraphic sequence analysis in terrestrial aggrading basin: sequence stratigraphy of Narrabeen Group, Sydney basin, Australia

    SciTech Connect

    Reynolds, S.A.; Galloway, W.E.

    1989-03-01

    Development of event/sequence stratigraphy concepts over the past 15 years has been one of the most significant contributions to systematic stratigraphic analyses of sedimentary basins. Most of these approaches, however, have not been applied to terrestrial aggradational settings but rather were developed in marginal basin settings where progradational and transgressive units are important components of the sequence framework. The principal objective of sequence definition is the identification of genetic stratigraphic units that share a common paleogeographic, climatic, and tectonic origin. Thus, the basic premise of sequence stratigraphy should be useful in the delineation of the depositional framework for any basin. Criteria were devised to identify three genetic stratigraphic sequences within the Triassic Narrabeen Group of the Sydney basin, an aggrading basin with a terrestrial fill. Individual sequences were chosen to emphasize significant changes in tectonic and climatic conditions, as reflected in the distinguishing characteristics of depositional style, sediment composition, and paleodrainage trends. The Munmorah sequence is characterized by lithic sandstone deposits of an extensive alluvial plain sourced by the New England foldbelt to the northeast. The overlying Bulgo sequence is distinguished by changes in sediment transport direction, lithology, and depositional style. The western Lachlan foldbelt emerged as a source of a quartz-rich braid-plain system. The Bald Hill sequence lies above the Bulgo and consists of sandstones and kaolinitic claystones that were deposited in extensive, highly oxidized alluvial plains that were dissected by numerous small streams. The distinctive mineralogy and depositional style of the Bald Hill deposits suggest climatic and tectonic changes in the Lachlan foldbelt source area.

  18. Stratigraphic condensation of marine transgressive records: Origin of major shell deposits in the Miocene of Maryland

    SciTech Connect

    Kidwell, S.M. )

    1989-01-01

    Cyclic stratigraphic sequences in shallow marine records are commonly charaterized by a condensed transgressive lag at the base of thicker, shallowing-upward facies. The standard actualistic model for these thin fossiliferous lags, by which most of the shelf is starved owing to coastal trapping of sediment and fossils are suspected of being reworked because of the association with an erosional ravinement, is contradicted by detailed stratigraphic and taphonomic analysis of Miocene examples in the Maryland coastal plain. The complex internal stratigraphies of the shell deposits and the mixture of soft- and shell-bottom faunas indicate condensation under a regime of dynamic bypassing rather than complete sediment starvation; bypassed fine sediments accumulated in deeper water environments below storm wavebase. Deeper, even more basinward parts of the shelf were starved of all sediment size fractions and accumulated shell-poor, bone-rich condensed deposits that lie mid-cycle (bracketing the time of maximum water depth). The base-of-cycle shell deposits and mid-cycle bone bed differ not only in composition and in environment and dynamics of condensation, but also in chronostratigraphic value: the onlapping shell deposits must be diachronous to some degree, whereas the mid-cycle bone bed approximates an isochronous marker for correlation. Thus, in some settings at least, transgressive shelves present a spatial mosaic of condensational and depositional regimes. Regardless of origin, all condensed intervals can time-average assemblages and telescope biostratigraphic datums. They otherwise differ widely, however, in paleontologic attributes and are characterized by highly variable and complex stratigraphic anatomies.

  19. Implications of new stratigraphic data on volcanic hazard assessment for Nisyros volcano, Greece

    NASA Astrophysics Data System (ADS)

    Volentik, A.; Vanderkluysen, L.; Principe, C.; Hernandez, J.; Hunziker, J. C.

    2003-04-01

    The active quaternary Nisyros volcano, at the eastern end of the Aegean volcanic arc, is composed of a succession of lava flows, tephra layers and interbedded epiclastic deposits. The volcano is topped by a recent caldera, on average 4 km in diameter and 200 m in depth. A detailed geological map including 35 stratigraphic units (lava flows, tephra layers and epiclastic deposits) has been recently completed at the 1:10'000 scale, based on new stratigraphical data. Based on the identification of new plinian sequences (Lakki and Melisseri pyroclastic series) in the lowermost section of the reconstructed stratigraphical succession, on the re-interpretation of previously described deposits and on the discovery of eruptive facies, we construct a set of hazard maps for volcanic events at Nisyros. Sequences of sub-marine lavas to subaerial epiclastites combined with the occurrence of a marine terrace deposit in the north-western sector of the island highlight the potential for rapid vertical movements, in particular in the area of Mandraki. A period of intense off-centred strombolian to phreatomagmatic activity occurred in quite recent times on Nisyros along the major tectonic trends (N^o030, No070, N^o120 and N^o340), building up several scoria cones and tuff cones all around the island. A number of these tectonic trends are still active, as demonstrated by faults cutting through recent deposits (including the youngest deposits of the hydrothermal eruptions, inside the present caldera of Nisyros). This implies that not only intra-caldera phreatic eruptions, but also potential magmatic eruption may occur along the islands major zones of weakness, with increased hazards where magma/water interaction may take place. Finally a newly recognized debris avalanche deposit (the so-called Vunri debris avalanche), affecting a wide sector in the northern part of the island, unveils a new type of volcanic hazard on Nisyros, related to flank collapse and destruction of the volcanic edifice.

  20. Sequence stratigraphy and stratigraphic trap potential of the Villeta Formation (Cretaceous), Putumayo Basin, Columbia

    SciTech Connect

    Robertson, H.C. ); Cregg, A.; Cleveland, G. )

    1996-01-01

    The Villeta Formation, which was deposited in -15 Ma (Cenomanian-Campanian), includes four 3rd-order sequences representing marine shelf, siliciclastic shoreface, and lower coastal-plain environments. Although these environments transgressed landward across the pre-Cretaceous basement during a 2nd-order base-level rise, several brief but important base-level falls and abrupt basinward and downward facies-shifts interrupted this trend. The 3rd-order base-level falls and subsequent transgressions led to the deposition of important hydrocarbon-bearing sandstones in the Villeta Formation. Sequence boundaries record abrupt downward facies shifts and separate black marine shales and deep-shelf limestones below from fluvial to tidally- and wave-influenced shoreface sandstones above. Each of these sands (Arenisca T, U inferior, U superior, and M2) laps out landward and passes upward into transgressive shales and thin highstand limestones. Base-level rise and retrogradation of the shoreline is indicated by upward thinning of transgressive sandstones and upward increase in marine shale. Sandstones thin or downlap basinward into shales. Transgressive deposits dominate the sequences. Highstand progradation of siliciclastic shorelines was minimal and limited by a relatively high accommodation/sediment-supply ratio. Base-level falls, however, allowed shorelines to advance basinward long distances. The stratigraphic geometries of the Villeta sandstones, as indicated by seismic data and well-log correlations, indicate that potentially large stratigraphic traps are present in the Putumayo Basin. Stratigraphic entrapment is indicated by landward onlap of the Villeta sandstones, the presence of shales and tight limestones overlying porous sandstones, and known hydrocarbon accumulations in the sandstones over structural highs.

  1. Sequence stratigraphy and stratigraphic trap potential of the Villeta Formation (Cretaceous), Putumayo Basin, Columbia

    SciTech Connect

    Robertson, H.C.; Cregg, A.; Cleveland, G.

    1996-12-31

    The Villeta Formation, which was deposited in -15 Ma (Cenomanian-Campanian), includes four 3rd-order sequences representing marine shelf, siliciclastic shoreface, and lower coastal-plain environments. Although these environments transgressed landward across the pre-Cretaceous basement during a 2nd-order base-level rise, several brief but important base-level falls and abrupt basinward and downward facies-shifts interrupted this trend. The 3rd-order base-level falls and subsequent transgressions led to the deposition of important hydrocarbon-bearing sandstones in the Villeta Formation. Sequence boundaries record abrupt downward facies shifts and separate black marine shales and deep-shelf limestones below from fluvial to tidally- and wave-influenced shoreface sandstones above. Each of these sands (Arenisca T, U inferior, U superior, and M2) laps out landward and passes upward into transgressive shales and thin highstand limestones. Base-level rise and retrogradation of the shoreline is indicated by upward thinning of transgressive sandstones and upward increase in marine shale. Sandstones thin or downlap basinward into shales. Transgressive deposits dominate the sequences. Highstand progradation of siliciclastic shorelines was minimal and limited by a relatively high accommodation/sediment-supply ratio. Base-level falls, however, allowed shorelines to advance basinward long distances. The stratigraphic geometries of the Villeta sandstones, as indicated by seismic data and well-log correlations, indicate that potentially large stratigraphic traps are present in the Putumayo Basin. Stratigraphic entrapment is indicated by landward onlap of the Villeta sandstones, the presence of shales and tight limestones overlying porous sandstones, and known hydrocarbon accumulations in the sandstones over structural highs.

  2. Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: Implications for emission modeling

    NASA Astrophysics Data System (ADS)

    Rutter, Nick; Sandells, Mel; Derksen, Chris; Toose, Peter; Royer, Alain; Montpetit, Benoit; Langlois, Alex; Lemmetyinen, Juha; Pulliainen, Jouni

    2014-03-01

    Two-dimensional measurements of snowpack properties (stratigraphic layering, density, grain size, and temperature) were used as inputs to the multilayer Helsinki University of Technology (HUT) microwave emission model at a centimeter-scale horizontal resolution, across a 4.5 m transect of ground-based passive microwave radiometer footprints near Churchill, Manitoba, Canada. Snowpack stratigraphy was complex (between six and eight layers) with only three layers extending continuously throughout the length of the transect. Distributions of one-dimensional simulations, accurately representing complex stratigraphic layering, were evaluated using measured brightness temperatures. Large biases (36 to 68 K) between simulated and measured brightness temperatures were minimized (-0.5 to 0.6 K), within measurement accuracy, through application of grain scaling factors (2.6 to 5.3) at different combinations of frequencies, polarizations, and model extinction coefficients. Grain scaling factors compensated for uncertainty relating optical specific surface area to HUT effective grain size inputs and quantified relative differences in scattering and absorption properties of various extinction coefficients. The HUT model required accurate representation of ice lenses, particularly at horizontal polarization, and large grain scaling factors highlighted the need to consider microstructure beyond the size of individual grains. As variability of extinction coefficients was strongly influenced by the proportion of large (hoar) grains in a vertical profile, it is important to consider simulations from distributions of one-dimensional profiles rather than single profiles, especially in sub-Arctic snowpacks where stratigraphic variability can be high. Model sensitivity experiments suggested that the level of error in field measurements and the new methodological framework used to apply them in a snow emission model were satisfactory. Layer amalgamation showed that a three-layer representation of snowpack stratigraphy reduced the bias of a one-layer representation by about 50%.

  3. Stable isotopes of carbon as an invaluable stratigraphic tool: An example from the Cambrian of the northern Appalachians, USA

    NASA Astrophysics Data System (ADS)

    Glumac, Bosiljka; Spivak-Birndorf, Malkah L.

    2002-06-01

    This study illustrates the usefulness of carbon isotopes in stratigraphic interpretations of poorly fossiliferous strata beyond the resolution possible by biostratigraphy. The Upper Cambrian strata of the lower Gorge Formation in northwestern Vermont have been interpreted as highly condensed continental-slope deposits with a hiatus bracketed by the trilobite fauna of the Dunderbergia zone (Steptoean) and the Saukia zone (upper Sunwaptan). This interpretation was based on information from two thin fossiliferous intervals, the occurrence of one of them being unconfirmed in a recent study. Carbon isotopes provide a means for testing this interpretation because marine carbonate rocks deposited during the Steptoean Age of the Late Cambrian record a large, global, positive carbon isotope excursion (δ13C values of up to +5‰ relative to the Vienna Peedee belemnite standard). If the proposed age for the lowermost Gorge Formation is correct, these strata should record the start of the excursion, and the hiatus should produce an abrupt termination in the record of the excursion near maximum values. The determined δ13C values (-0.57‰ to +0.39‰) indicate that the excursion is not recorded at this locality. The results question the age for these strata and suggest that the hiatus is greater than previously recognized, encompassing most of the Steptoean. This major sedimentary hiatus lends supporting evidence for a significant eustatic or pan-Laurentian sea- level event during the Steptoean perturbation in the global cycling of carbon.

  4. The Offshore East African Rift System

    NASA Astrophysics Data System (ADS)

    Franke, D.; Klimke, J.; Jokat, W.; Stollhofen, H.; Mahanjane, S.

    2014-12-01

    Numerous studies have addressed various aspects of the East African Rift system but surprisingly few on the offshore continuation of the south-eastern branch of the rift into the Mozambique Channel. The most prominent article has been published almost 30 years ago by Mougenot et al. (1986) and is based on vintage seismic data. Several studies investigating earthquakes and plate motions from GPS measurements reveal recent deformation along the offshore branch of the East African Rift system. Slip vectors from earthquakes data in Mozambique's offshore basins show a consistent NE direction. Fault plane solutions reveal ~ E-W extensional failure with focal depth clustering around 19 km and 40 km, respectively. Here, we present new evidence for neotectonic deformation derived from modern seismic reflection data and supported by additional geophysical data. The modern rift system obviously reactivates structures from the disintegration of eastern Gondwana. During the Jurassic/Cretaceous opening of the Somali and Mozambique Basins, Madagascar moved southwards along a major shear zone, to its present position. Since the Miocene, parts of the shear zone became reactivated and structurally overprinted by the East African rift system. The Kerimbas Graben offshore northern Mozambique is the most prominent manifestation of recent extensional deformation. Bathymetry data shows that it deepens northwards, with approximately 700 m downthrown on the eastern shoulder. The graben can be subdivided into four subbasins by crosscutting structural lineaments with a NW-SE trend. Together with the N-S striking graben-bounding faults, this resembles a conjugate fault system. In seismic reflection data normal faulting is distinct not only at the earthquake epicenters. The faults cut through the sedimentary successions and typically reach the seafloor, indicating ongoing recent deformation. Reference: Mougenot, D., Recq, M., Virlogeux, P., and Lepvrier, C., 1986, Seaward extension of the East African Rift: Nature, v. 321, p. 599-603

  5. Rocky and Sandy Seafloor Offshore California

    USGS Multimedia Gallery

    Image of ripples in sand, next to a rocky surface on the seafloor 2.5 km (1.5 miles) offshore San Mateo County, California at a depth of 24.6 meters (81 feet). The two red dots in the image (from lasers mounted on the camera and used as reference points) are 15 cm (6 inches) apa...

  6. Protective riser-conductor for offshore structures

    SciTech Connect

    Rutherford, D. A.; Albers, G. P.

    1985-07-09

    A protective sleeve for fitting about the periphery of the leg of an offshore structure. The sleeve comprises means for carrying and enclosing a plurality of conductors. It further includes one or more inner rings; an outer jacket is fixedly spaced from the rings to define longitudinal passages within which the respective conductors are fixedly positioned. The sleeve is capable of deflecting packed ice and floating objects which represent possible sources of damage to the structure or to conductors.

  7. Automatic welding comes of age. [Offshore

    SciTech Connect

    Turner, D.L. Jr.

    1981-07-01

    Automatic pipe welding systems today fall into three main categories: gas metal arc welding, gas-tungsten arc welding, and flash-butt welding. The first automatic welding devices used offshore were the CRC and H.C. Price systems. Both use gas metal arc welding with a consumable steel filler wire. The recently developed McDermott flash-butt welding system is described. (DLC)

  8. Centrifuge modelling of foldthrust structures in a tripartite stratigraphic succession

    NASA Astrophysics Data System (ADS)

    Dixon, John M.; Tirrul, Rein

    Analog models measuring 127 76 mm in plan were deformed at 2500-4000 g in a centrifuge. Scaled stratigraphic sequences were constructed of anisotropic multilayers with individual layers of Plasticine and silicone putty as thin as 40 ?m. The plasticinesilicone putty multilayers are analogs for interbedded competent carbonates and clastics, and incompetent pelites, given the model ratios of acceleration, 2500 g; length, 5 10 -6; specific gravity, 0.6; time 10 -10. Modelling of foldthrust tectonics emphasizes the influence of stratigraphic succession on structural evolution. The models are constructed with a tripartite stratigraphic succession comprising basal and upper, well-laminated and incompetent units, and a middle, somewhat more isotropic and competent unit. The models deform by three mechanisms: layer-parallel shortening, folding and thrust faulting. They reproduce a number of foldthrust relationships that have been observed in nature. Folds are typically periclinal, in en chelon arrays. Folds and thrusts are arcuate in plan, reflecting differential shortening. Fold attitudes grade from upright at high levels to overturned at deeper levels within a structural panel, reflecting drag against the basal dcollement; fold axial surfaces and thrust faults are listric. While competent units may be offset by localized displacement on thrust faults, the discrete faults may die out both upwards and downwards into regions of ductile strain in less-competent units. Thrust faults appear to follow staircase trajectories through the strata, transecting incompetent units at shallow angles to bedding and competent units at steeper angles. However, the apparent staircase pattern results from propagation of a fault along a relatively straight trajectory through previously-folded strata. Foreland-verging thrusts are more common than back thrusts; the latter have steeper dips. The models suggest a mechanism of thrust-ramp nucleation following detachment folding: long-wavelength buckling of a competent unit can initiate localized strain (folding and layer-parallel shear) in an underlying incompetent unit, beneath the anticlines of the competent unit; thrust faults propagate up-section from these high-strain zones through the foreland-dipping limbs of buckle-folds in the competent unit. This mechanism may explain the commonly-observed spatial periodicity of thrust ramps. The model results bear similarities to natural foldthrust belts in which the stratigraphic succession consists of three mechanical units, for example, the Asiak Foreland and Bear Creek Hills foldthrust belts of the Slave Province, Northwest Territories, Canada.

  9. EXPLORING FOR SUBTLE MISSION CANYON STRATIGRAPHIC TRAPS WITH ELASTIC WAVEFIELD SEISMIC TECHNOLOGY

    SciTech Connect

    John Beecherl

    2004-02-01

    The 9C3D seismic data that will form the principal data base needed for this research program have been successfully acquired. The seismic field data exhibit a good signal-to-noise (S/N) ratio for all elastic-wave modes. Thus the major hurdle of acquiring optimal-quality 9-C seismic data has been cleared. The stratigraphic oil-reservoir target that will be the imaging objective of the seismic data-processing effort is described in this report to indicate the challenge that now confronts the data-processing phase of the project.

  10. Can a time-stratigraphic classification system be developed for Venus?

    NASA Technical Reports Server (NTRS)

    Tanaka, K. L.; Schaber, G. G.

    1992-01-01

    Magellan radar images reveal that Venus' exposed geologic record covers a relatively short and recent time span, as indicated by the low density of impact craters across the planet. Therefore, because impact cratering in itself will not be a useful tool to define geologic ages on Venus, it was questioned whether a useful stratigraphic scheme can be developed for the planet. We believe that a venusian stratigraphy is possible and that it can be based on the following: (1) an examination of the rationale and methods that have been used to develop such schemes for the other planets; and (2) what can be gleaned from Magellan and other datasets of Venus.

  11. Stratigraphic evidence of desertification in the west-central Great Plains within the past 1000 yr

    USGS Publications Warehouse

    Madole, R.F.

    1994-01-01

    Stratigraphic and geomorphic relations, archaeological data, and eight radiocarbon ages at five widely scattered localities in northeastern Colorado indicate that eolian sand was mobilized over broad areas within the past 1000 yr. The mobilization began after 1 ka, was episodic, and ended at some as yet undetermined time prior to the latter part of the 19th century. Given that climate-model simulations suggest only slight variation in average surface temperature and annual precipitation in this region during the past 1000 yr, this part of the Great Plains evidently is near the threshold of widespread eolian sand transport under the present climate. -Author

  12. Stratigraphic context and direct dating of the Neandertal mandible from Cova del Gegant (Sitges, Barcelona).

    PubMed

    Daura, J; Sanz, M; Pike, A W G; Subir, M E; Forns, J J; Fullola, J M; Juli, R; Zilho, J

    2010-07-01

    Stratigraphic study of the Cova del Gegant's sedimentary fill revealed different cycles of accumulation of typical interior cave and delta facies. A precise chronology for these deposits, the faunal remains and stone tools contained therein was obtained by radiocarbon, U-Th and OSL. Our results indicate that the Upper Pleistocene archaeological sequence dates between 49.3 +/- 1.8 ka BP, the U-Th age of the overlying flowstone, and 60.0 +/- 3.9 ka BP, the OSL age of the basal deposits. We have also directly dated the site's Neandertal mandible to 52.3 +/- 2.3 ka by U-Th. PMID:20570316

  13. Simplified stratigraphic cross sections of the Eocene Green River Formation in the Piceance Basin, northwestern Colorado

    USGS Publications Warehouse

    Dietrich, John D.; Johnson, Ronald C.

    2013-01-01

    Thirteen stratigraphic cross sections of the Eocene Green River Formation in the Piceance Basin of northwestern Colorado are presented in this report. Originally published in a much larger and more detailed form by Self and others (2010), they are shown here in simplified, page-size versions that are easily accessed and used for presentation purposes. Modifications to the original versions include the elimination of the detailed lithologic columns and oil-yield histograms from Fischer assay data and the addition of ground-surface lines to give the depth of the various oil shale units shown on the cross section.

  14. Stratigraphic framework of Cambrian and Ordovician rocks across Rome Trough, central Appalachian basin

    SciTech Connect

    Ryder, R.T.

    1987-09-01

    Restored stratigraphic cross sections drawn primarily through the subsurface of parts of Pennsylvania, Ohio, West Virginia, Kentucky, and Tennessee provide new detailed information to further the understanding of Cambrian and Ordovician sedimentation and tectonics associated with the Rome trough sector of the Appalachian basin. Drilled thickness of the Cambrian and Ordovician sequence ranges from a maximum of about 14,500 ft (4.5 km) along the axis of the trough to a minimum of about 3500 ft (1 km) on the western flank.

  15. Lake Tapps tephra: An early Pleistocene stratigraphic marker in the Puget Lowland, Washington

    USGS Publications Warehouse

    Westgate, J.A.; Easterbrook, D.J.; Naeser, N.D.; Carson, R.J.

    1987-01-01

    The rhyolitic Lake Tapps tephra was deposited about 1.0 myr ago, shortly after culmination of the early phase of the Salmon Springs Glaciation in the Puget Lowland. It is contained within sediments that were deposited in ponds or lakes in front of the reteating glacier. An herb-dominated tundra existed in the southern Puget Lowland at that time. Lake Tapps tephra is most likely the product of an eruption that in part was phreatomagmatic. It forms an early Pleistocene stratigraphic marker across the southern sector of the Puget Lowland and provides a link between Puget lobe sediments of the Cordilleran Ice Sheet and sediments deposited by Olympic alpine glaciers. ?? 1987.

  16. Stratigraphic permeability in the Baca geothermal system, Redondo Creek Area, Valles Caldera, New Mexico

    SciTech Connect

    Hulen, J.B.; Nielson, D.L.

    1982-10-01

    Synthesis of surface and borehole data from the Baca geothermal system, as defined by drilling to date in the Redondo Creek area of the Valles Caldera, New Mexico, indicates that thermal fluid flow in the system is partially controlled by distinct stratigraphic aquifers. These aquifers are relatively thin, laterally restricted beds of non-welded tuff and tuffaceous sandstone, confined primarily to the Quaternary Bandelier Tuff. Recognition of the role of these rocks in reservoir definition at Baca should improve chances for future geothermal discoveries in the Valles Caldera and similar settings elsewhere.

  17. The Deccan tholeiite lavas and dykes of Ghatkopar-Powai area, Mumbai, Panvel flexure zone: Geochemistry, stratigraphic status, and tectonic significance

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Zellmer, Georg F.; Demonterova, Elena I.; Ivanov, Alexei V.; Kumar, Rohit; Patel, Rakesh Kumar

    2014-04-01

    Mumbai City, situated on the western Indian coast, is well known for exposures of late-stage Deccan pillow basalts and spilites, pyroclastic rocks, rhyolite lavas, and trachyte intrusions. These rock units, and a little-studied sequence of tholeiitic flows and dykes in the eastern part of Mumbai City, constitute the west-dipping limb of a regional tectonic structure called the Panvel flexure. Here we present field, petrographic, major and trace element and Sr-Nd isotopic data on these tholeiitic flows and dykes, best exposed in the Ghatkopar-Powai area. The flows closely resemble the Mahabaleshwar Formation of the thick Western Ghats sequence to the east, in Sr-Nd isotopic ratios and multielement patterns, but have other geochemical characteristics (e.g., incompatible trace element ratios) unlike the Mahabaleshwar or any other Formation. The flows may have originated from a nearby eruptive center, possibly offshore of Mumbai. Two dykes resemble the Ambenali Formation of the Western Ghats in all geochemical characteristics, though they may not represent feeders of the Ambenali Formation lavas. Most dykes are distinct from any of the Western Ghats stratigraphic units. Some show partial (e.g., Sr-Nd isotopic) similarities to the Mahabaleshwar Formation, and these include several dykes with unusual, concave-downward REE patterns suggesting residual amphibole and thus a lithospheric source. The flows and dykes are inferred to have undergone little or no contamination, by lower continental crust. Most dykes are almost vertical, suggesting emplacement after the formation of the Panvel flexure, and indicate considerable east-west lithospheric extension during this late but magmatically vigorous stage of Deccan volcanism.

  18. Caisson shield for arctic offshore production platform

    SciTech Connect

    Clinton, J. D.; Reusswig, G. H.

    1985-03-12

    A caisson shield for the protection of an offshore production platform and, more particularly, a caisson shield for use in an arctic environment for the protection of the offshore structure in iceberg-infested waters which is capable of absorbing the destructive forces of an impact produced by a large iceberg. The caisson shield consists of an essentially annular concrete structure encircling at least the submerged support section of the offshore production platform including vertically upstanding concentrically spaced, annular side walls, a horizontal slab base resting on the marine bottom on which the side walls are supported, and a slab top supported on the side walls, and including annularly spaced internal radial partition walls whereby the entire overall caisson shield structure provides a generally toroidal configuration incorporating a plurality of closed compartments. In one embodiment of the invention, located along the outer annular wall is a plurality of arcuate wall sections forming a series of arches and enclosed compartments between each arcuate wall section and the outer annular wall, which impart a ''scallop-like'' configuration to the outer circumference of the caisson shield. The ''scallop-like'' outer walls are capable of resisting and absorbing extremely high ice loads by being adapted to progressively crush the leading edge of an impacting iceberg and to thereby minimize the crush of the iceberg against the caisson shield before coming to rest against the shield.

  19. Geomorphic and stratigraphic evidence for dynamic river channel development in the Dehra Dun region, northern India

    NASA Astrophysics Data System (ADS)

    Densmore, A. L.; Sinha, R.; Barnes, J. B.; Pickering, J.; Tandon, S. K.

    2009-04-01

    The Ganga and Yamuna rivers drain the Garhwal Himalaya of northern India and cut cross several active faults as they pass into the Gangetic Plain and the northern Indian foreland. Unlike rivers in the central or eastern Himalayas, which debouch directly into the foreland and have built large depositional fan complexes, the Ganga and Yamuna rivers have been funnelled into an intermontane basin, the Dehra Dun, by Quaternary upper-crustal faulting and growth of the Mohand anticline. Sediments in the Dun record a complex history of aggradation and erosion during the Quaternary, as seen by alternate episodes of fan progradation and incision in stratigraphic records. Here, we summarize existing work on the evidence for, and timing of, these episodes, and explore the consequences of proximal sediment storage or evacuation, as well as local sediment sources derived from the active structures bounding the Dun, on the downstream character and behaviour of the river systems. Correlation of fan depositional surfaces across the Dun allows us to constrain both the volumes of Quaternary fill in the Dun and the amount of material excavated during episodes of fan incision. We argue that, while the trapping of sediment in the Dun is ultimately caused by growth and lateral propagation of the Himalayan frontal fault system and the Mohand anticline, variations in storage or excavation on short time scales (50-100 ka to present) are most likely driven by climatically-modulated changes in sediment supply from the catchments upstream of the Dun. We show that active upper-crustal faulting does, however, leave a consistent imprint in the present-day morphology of the rivers as they flow across the Dun. Finally, we place bounds on the volumes of sediment sourced from the active structures bounding the Dun, including the Mohand anticline, and the approximate time scales over which this sediment has been liberated. An open question is whether or not the proximal sediment storage ‘filter' of the Dun plays a significant role in modulating the sediment flux in the Ganga and Yamuna systems. It seems likely that such a filter will amplify climate-related fluctuations in sediment supply from the Higher and Lesser Himalaya. For example, widespread trapping of sediment in the Dun would be expected to trigger downstream incision across the Gangetic Plain, which in turn would inhibit large-scale avulsion of the river course. The relative lack of proximal storage in eastern Gangetic river systems, such as the Kosi River in north Bihar, coupled with their higher sediment fluxes and precipitation rates, may be a contributing factor to their long-term hyper-avulsive behaviour. The degree of proximal storage may thus play an important contributing role in determining large-scale flood hazard across the Gangetic Plain. Only a better understanding of the timing of river incision and aggradation in the Gangetic Plain, as well as the magnitude and duration of sediment storage in the Dun and other intermontane valleys, will enable this hypothesis to be more fully tested.

  20. 30 CFR 251.7 - Test drilling activities under a permit.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... relating to drilling operations in 30 CFR part 250. (7) Revising an approved drilling plan. Before you... stratigraphic tests in compliance with 30 CFR part 250. If the tract on which you conducted a deep stratigraphic... information on the area: (A) Geology; (B) Physical oceanography; (C) Other uses of the area; (D) Flora...

  1. 30 CFR 251.7 - Test drilling activities under a permit.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... relating to drilling operations in 30 CFR part 250. (7) Revising an approved drilling plan. Before you... stratigraphic tests in compliance with 30 CFR part 250. If the tract on which you conducted a deep stratigraphic... information on the area: (A) Geology; (B) Physical oceanography; (C) Other uses of the area; (D) Flora...

  2. Development and application of oil-spill risk assessment model for offshore pipeline

    NASA Astrophysics Data System (ADS)

    Lu, Yan; Wang, Jia; Wei, Wenpu; Yang, Yong; An, Wei

    2014-06-01

    To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden oil-spill from the offshore pipeline has been raised. In this paper, we proposed an optimized model to analyze the main causes (probability) of spill and the consequence with the fuzzy comprehensive assessment model. Considering the complicated assessment process for oil-spill, the assessment factor system involving the spill probability and consequence was established based on the operative manual and statistic leakage/damage data of offshore pipeline in order to estimate the integrated spill risk score automatically. The evaluated factors of spill probability could be grouped into five aspects: corrosion, fatigue, national damage, third party, and operational fault; the consequence evaluated factors of spill included hazard of oil and impact-controlling capability. With some modifications based on experts' opinions, each of the evaluated factors in our work was developed with a relative weight and evaluation criterion. A test example for an offshore pipeline in the Bohai waters was described to show how the model can be used for an actual case in more detail. By using the oil-spill risk assessment model, it is easy to determine the risk level associated with the ongoing activity and management level and hence to take the risk mitigation action immediately.

  3. Integration of offshore wind farms through high voltage direct current networks

    NASA Astrophysics Data System (ADS)

    Livermore, Luke

    The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared..

  4. Sequence Stratigraphic Characterization of Upper Miocene through Pleistocene Siliciclastic Aquifer Sediments, Baton Rouge Area, Southeastern Louisiana Gulf Coast

    NASA Astrophysics Data System (ADS)

    Chamberlain, E. L.; Hanor, J. S.; Tsai, F. T.

    2012-12-01

    Saltwater encroachment northward into freshwater sands of the Baton Rouge aquifer system, southeastern Louisiana, poses a serious environmental threat to this metropolitan municipal and industrial water source. The aquifer system consists of an 850-m thick succession of interbedded, unconsolidated south-dipping siliciclastic sandy units and mudstones of Upper Miocene through Pleistocene age. A geology-based understanding of the connectivity, geometry and depositional setting of this aquifer system is necessary for developing strategies to halt or control saltwater intrusion. Seventy five digitized spontaneous potential - resistivity logs for boreholes in the area provided data for interpreting environments of deposition, for correlating sand-rich and mudstone-rich zones, and for identifying periods of low and high rates of sediment aggradation. The sands have complex geometries representing braided stream, meandering channel fill, floodplain, levee, and crevasse splay facies. A high degree of lateral discontinuity of the sands makes visual correlation of units difficult. Therefore an assessment of lithology-depth relations was made by determining the frequency of occurrence of mudstone at discrete 0.15 m depth intervals in borehole logs along five 40-km long transects parallel to the strike of the aquifer units. Percent occurrence of mudstone was graphed as a function of depth using a 41-point centered moving average for smoothing, and mudstone-poor, sand-rich trends were correlated between transects. Ten major sand cycles were identified. Individual aquifer units are interpreted to be complex zones of amalgamated sand bodies deposited during times of low aggradation associated with sea-level falling-stages and lowstand system tracts. The amalgamation created a high degree of connectivity which results in these zones behaving as single hydrologic units. Mudstone-rich aquitard sequences are interpreted to be flood-plain sediments deposited during times of high aggradation associated with sea-level highstands. Superimposed on this longer-term allogenic forcing caused by sea-level changes are shorter-term autogenic events, such as avulsion, which can be recognized from three-dimensional representations of sand body geometries. The ten sandy units identified are less than the 24 relative sea-level reversals documented in Gulf of Mexico offshore marine sequences for the Upper Miocene through the Pleistocene. However, some of these reversals were of short duration and limited magnitude and were not captured as major sequences in the lithology-depth curves generated in this study. In addition, major erosional events in the study area may have removed portions of the geologic record. Sequence stratigraphic characterization provides a process-oriented basis for understanding the origin of the details of the architecture and the hydrologic behavior of these units and is an effective tool for analyzing this highly complex aquifer system.

  5. The public's trust in scientific claims regarding offshore oil drilling.

    PubMed

    Carlisle, Juliet E; Feezell, Jessica T; Michaud, Kristy E H; Smith, Eric R A N; Smith, Leeanna

    2010-09-01

    Our study examines how individuals decide which scientific claims and experts to believe when faced with competing claims regarding a policy issue. Using an experiment in a public opinion survey, we test the source content and credibility hypotheses to assess how much confidence people have in reports about scientific studies of the safety of offshore oil drilling along the California coast. The results show that message content has a substantial impact. People tend to accept reports of scientific studies that support their values and prior beliefs, but not studies that contradict them. Previous studies have shown that core values influence message acceptance. We find that core values and prior beliefs have independent effects on message acceptance. We also find that the sources of the claims make little difference. Finally, the public leans toward believing reports that oil drilling is riskier than previously believed. PMID:21553598

  6. Sequence stratigraphy of the Hith/Upper Arab formations offshore Abu Dhabi, U.A.E.

    SciTech Connect

    Azer, S.R.; Peebles, R.G.

    1995-11-01

    The Kimmeridgian Upper Arab zones A, B, and C, are prolific hydrocarbon bearing reservoirs in central and western Offshore Abu Dhabi (OAD). They were deposited in an arid climate which dominated the Arabian peninsula during Late Jurassic times. The Berriasian to Tithonian Hith Formation which overlies the Arab reservoirs constitute the cap rock, which just to the east of central OAD gradually pinches out and forms a N-S feather edge. The Hith and Upper Arab zones A, B, and C form 450 to over 600 feet of massive to interbedded anhydrites with varying proportions of limestones and dolomites in central and western OAD. The Arab Formation in OAD is a major regressive unit which was deposited on a broad carbonate platform and prograded eastwards into an open marine shelf environment. The objectives of this paper are to develop a sequence stratigraphic framework, emphasizing cyclicity, facies architecture and diagenesis. Core and well log data geared with various inorganic geochemical analyses from four wells are used to constrain the current uncertainties in age dating and integrate the diagenetic signatures in the patterns of relative sea level change which considerably control the formation of those parasequences. This effort will help in better understanding and possible prediction of porosity in such prospective reservoirs.

  7. A Neogene calcareous nannofossil biozonation scheme for the deep offshore Niger Delta

    NASA Astrophysics Data System (ADS)

    Fadiya, Lawrence Suyi; Salami, Babajide Moshood

    2015-12-01

    A detailed calcareous nannofossil analysis was carried out on the deep-water offshore Niger Delta strata penetrated by eight wells in order to erect a basin-wide Neogene biozonation scheme for the region. Four of the wells penetrated Miocene to Early Pliocene strata while the others drilled through Miocene sediments. The recorded rich and diversified nannofossil suites enabled the subdivision of the Neogene sequences into 13 zones [NN1 (CN1a) - Early Miocene to NN13 (CN10c) - Early Pliocene] and 15 subzones. Five (NN1, NN2, NN4, NN5 and NN11) zones are divided into subzones based on First and Last occurrences plus relative abundance of marker species. Dearth of nannofossils in the Middle Miocene NN5-NN8 zones precludes a refined zonation construction for the interval. Several new criteria are suggested for delineating new and previously erected zones. The resulting refined scheme offers an improved stratigraphic framework for correlation of thin reservoir units within and across Niger Delta fields.

  8. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H. ); Watkins, J.S. )

    1996-01-01

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  9. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H.; Watkins, J.S.

    1996-12-31

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  10. Seismic modeling for gas field development in offshore Niger Delta: A case history

    SciTech Connect

    Idowu, A.O. )

    1994-07-01

    In practice, seismic data has been used to map the geometry of events in the subsurface, mainly from reflection continuity and the character of reflection packages. Seismic modeling techniques are attempts to mathematically and geometrically represent the geology of the subsurface and to depict the interaction of the geology with a propagating seismic wave front. In the Niger delta, recent development in stratigraphic exploration has induced the examination of more subtle features of reflection, mainly polarity, amplitude, and waveform, to define the limits of seismic resolution and hence predict the geometry of the subsurface fluid and solid interfaces. The field being appraised for development in this study is located approximately 35 km offshore southeast of the Niger delta in a water depth ranging from 20 to 25 m, and the project involves a modeling evaluation of five sand units encountered at different levels in the subsurface. The sands being modeled occur within the Agbada Formation (Miocene age), an alternation sequence of transitional sands and shales characterized by high-amplitude, anomalous seismic events over the Nkop field. Structurally, the field is characterized by seaward facing, contemporaneous growth faults consisting mainly of a rollover anticline located in a regional fault couple, bounded to the north and south by a growth fault.

  11. 26th Annual offshore technology conference: 1994 Proceedings

    SciTech Connect

    Not Available

    1994-01-01

    This conference represents the world's largest and most comprehensive technical conference and exhibition on offshore resource development. The four proceedings volumes have been separated by major areas of interest with this volume containing papers relative to design of offshore platforms and marine riser systems. Papers deal with design, installation, fabrication, transport systems, mooring devices, repair methods, and development of satellite production facilities. Case histories on various offshore oil and gas fills are discussed along with economics of some applications and designs.

  12. Offshore Code Comparison Collaboration (OC3) for IEA Wind Task 23 Offshore Wind Technology and Deployment

    SciTech Connect

    Jonkman, J.; Musial, W.

    2010-12-01

    This final report for IEA Wind Task 23, Offshore Wind Energy Technology and Deployment, is made up of two separate reports, Subtask 1: Experience with Critical Deployment Issues and Subtask 2: Offshore Code Comparison Collaborative (OC3). Subtask 1 discusses ecological issues and regulation, electrical system integration, external conditions, and key conclusions for Subtask 1. Subtask 2 included here, is the larger of the two volumes and contains five chapters that cover background information and objectives of Subtask 2 and results from each of the four phases of the project.

  13. More gaps than shale: stratigraphic incompleteness of marine shale successions using a Toarcian example

    NASA Astrophysics Data System (ADS)

    Trabucho-Alexandre, J. P.

    2014-12-01

    Marine shale successions are probably the best archives of earth history. The degree of completeness of a marine shale succession is a critical factor in the interpretation of the geologic record of climatic, oceanic, and biogeochemical processes, in the prediction of timescales of those processes, in the determination of the duration of events, and in the establishment of correlations between successions. The sedimentation rates of marine shale successions are often calculated by dividing the thickness of a succession by the duration of the stratigraphic interval it occupies. Sedimentation rates calculated this way are always much lower than rates measured directly in equivalent modern environments. When we apply modern rates to the deposits left behind by their ancient equivalents, and correct for compaction due to overburden and time, we find that the entire succession can be deposited in a relatively short time. Since we know that the stratigraphic interval occupied by such ancient deposits is much longer, we must conclude that the succession is very incomplete. In this presentation, I will use a few different methods to show that 65 to >80% of the duration of the Toarcian oceanic anoxic event in Yorkshire, U.K., is represented by gaps rather than shale. This means that the Toarcian oceanic anoxic event is not as short as proposed by authors who studied the cyclostratigraphy of the Yorkshire succession, and that it probably represents a much longer-term history of environmental change driven by processes acting on longer time scales.

  14. Neoproterozoic-Cambrian stratigraphic framework of the Anti-Atlas and Ouzellagh promontory (High Atlas), Morocco

    NASA Astrophysics Data System (ADS)

    Álvaro, J. Javier; Benziane, Fouad; Thomas, Robert; Walsh, Gregory J.; Yazidi, Abdelaziz

    2014-10-01

    In the last two decades, great progress has been made in the geochronological, chrono- and chemostratigraphic control of the Neoproterozoic and Cambrian from the Anti-Atlas Ranges and the Ouzellagh promontory (High Atlas). As a result, the Neoproterozoic is lithostratigraphically subdivided into: (i) the Lkest-Taghdout Group (broadly interpreted at c. 800-690 Ma) representative of rift-to-passive margin conditions on the northern West African craton; (ii) the Iriri (c. 760-740 Ma), Bou Azzer (c. 762-697 Ma) and Saghro (c. 760?-610 Ma) groups, the overlying Anezi, Bou Salda, Dadès and Tiddiline formations localized in fault-grabens, and the Ouarzazate Supergroup (c. 615-548 Ma), which form a succession of volcanosedimentary complexes recording the onset of the Pan-African orogeny and its aftermath; and (iii) the Taroudant (the Ediacaran-Cambrian boundary lying in the Tifnout Member of the Adoudou Formation), Tata, Feijas Internes and Tabanite groups that have recorded development of the late Ediacaran-Cambrian Atlas Rift. Recent discussions of Moroccan strata to select new global GSSPs by the International Subcommissions on Ediacaran and Cambrian Stratigraphy have raised the stratigraphic interest in this region. A revised and updated stratigraphic framework is proposed here to assist the tasks of both subcommissions and to fuel future discussions focused on different geological aspects of the Neoproterozoic-Cambrian time span.

  15. Trace element geochemistry: New technology for stratigraphic correlations and formation evaluation

    SciTech Connect

    Lord, C.J.

    1995-09-01

    New technology based on the trace element chemistry of rocks is being developed as a tool for mapping subsurface formations in oilfields. This technology can be used to map rock formations in areas where traditional techniques are inconclusive. Trace element geochemistry complements and enhances conventional tools such as biostratigraphy, petrology, and log analysis. Applications cover a broad array of topics including stratigraphic correlations, interpretation of well log responses, age dating, and investigations of reservoir rock properties. Current work is focusing on identifying trace element fingerprints that uniquely mark specific subsurface horizons. There is convincing evidence that trace element fingerprints retain their relative stratigraphic position even though the original mineralogy of the rock has been extensively altered. This means that many of the trace elements associated with specific subsurface rock strata remain in place and are simply transferred from the original mineral to a new (alteration product) mineral. The immobility of these elements is an important geochemical feature because virtually all of the rocks encountered in the petroleum industry are altered to some extent. The ability to {open_quotes}see through{close_quotes} alteration events and obtain information about the original rock is a key advantage of trace element geochemistry techniques.

  16. Recognition of eustatic versus tectonic signatures in the carbonate sequence stratigraphic record

    SciTech Connect

    Lindsay, R.F.

    1996-12-31

    In the process of building sequence stratigraphic models it has become apparent that both eustatic and tectonic signatures can be recognized in the sequence stratigraphic record. Tectonics, active during deposition, modify the shelf to basin profile to leave a signature of increased or decreased rates of subsidence or uplift, or by quiescence. Subsidence or uplift may increase, decrease, or stop, and start again in short amounts of time. Tectonics can dramatically control the positioning of high to low quality reservoir rock. Eustatic sea level rise and fall may be synchronous or out of phase with tectonic events on the cycle, set, or sequence scale. On the sequence scale, if subsidence rates increased dramatically eustatic sea level rise and fall would deposit less complete shallowing-upward cycles in a transgressive systems tract. As subsidence slowed eustatic sea level would deposit complete cycles, containing exposure surfaces, in a highstand systems tract. If the basement is broken into discrete blocks, individual blocks may adjust differentially. One block may subside while an adjacent block may be quiescent or slowly uplifting. If one block abruptly subsides adjacent to a block that did not, cycles in the subsiding block thicken to form a wedge. As subsidence slowed and became more uniform, cycles across the same area will be of equal thickness. If subsidence stopped entirely, subaerial exposure would create an unconformity. Blocks slowly uplifting during deposition would receive thinner cycles across that block or the cycles would onlap onto it, and appear as a bulge in the shelf to basin profile.

  17. Spheroidal carbonaceous fly ash particles provide a globally synchronous stratigraphic marker for the Anthropocene.

    PubMed

    Rose, Neil L

    2015-04-01

    Human impacts on Earth are now so great that they have led to the concept of a new geological epoch defined by this global human influence: the Anthropocene. While not universally accepted, the term is increasingly popular and widely used. However, even among proponents, there is considerable debate regarding when the epoch may have started, from coeval with the Holocene, through the Industrial Revolution, to the mid-20th century when unprecedented human activities resulted in exponential increases in population, resource consumption, and pollutant emission. Recently, this latter period, known as the Great Acceleration, appears to be becoming the more widely accepted start date. To define any start point, a global stratigraphic marker or Global Boundary Stratotype Section and Point (GSSP) is typically required. Here, spheroidal carbonaceous fly ash particles (SCPs), byproducts of industrial fossil-fuel combustion, are proposed as a primary marker for a GSSP at the time of the Great Acceleration. Data from over 75 lake sediment records show a global, synchronous, and dramatic increase in particle accumulation starting in c. 1950 driven by the increased demand for electricity and the introduction of fuel-oil combustion, in addition to coal, as a means to produce it. SCPs are morphologically distinct and solely anthropogenic in origin, providing an unambiguous marker. This is a clear signal of great stratigraphic utility representing a primary driving force for global anthropogenic change. PMID:25790111

  18. Badenian (Middle Miocene) echinoids and starfish from western Ukraine, and their biogeographic and stratigraphic significance

    NASA Astrophysics Data System (ADS)

    Radwa?ski, Andrzej; Grka, Marcin; Wysocka, Anna

    2014-06-01

    Echinoderms from the Badenian (Middle Miocene) of the Fore-Carpathian Basin of western Ukraine are facies restricted. The Mykolaiv Beds, stratigraphically older, yielded the starfish Astropecten forbesi (complete skeletons), two genera of sand dollars (Parascutella, Parmulechinus), and numerous other echinoids of the genera Psammechinus , Echinocyamus, Spatangus, Hemipatagus, Echinocardium, Clypeaster, Echinolampas, and Conolampas. The stratigraphically younger, calcareous Ternopil Beds yielded Eucidaris (complete coronae, isolated spines), Arbacina , Brissus, and Rhabdobrissus. Sixteen species of echinoids are distinguished and/or commented. A new brissid, Rhabdobrissus tarnopolensis sp. nov., is established. A mass occurrence of some species (Psammechinus dubius and Hemipatagus ocellatus) contrasts with that of mass aggregations (sand dollars and Echinocardium leopolitanum) by dynamic events in selected layers of proximal tempestites. Of special note is the occurrence of very small specimens, interpreted as juveniles (`babies') having been swept out of their restricted biotopes (`nurseries'). Some species hitherto regarded as of Early Miocene age, and the problem of their persistence beyond the Fore-Carpathian Basin and/or migration into that basin during the Middle Miocene transgression are discussed.

  19. First high-resolution stratigraphic column of the Martian north polar layered deposits

    USGS Publications Warehouse

    Fishbaugh, K.E.; Hvidberg, C.S.; Byrne, S.; Russell, P.S.; Herkenhoff, K.E.; Winstrup, M.; Kirk, R.

    2010-01-01

    This study achieves the first high-spatial-resolution, layer-scale, measured stratigraphic column of the Martian north polar layered deposits using a 1m-posting DEM. The marker beds found throughout the upper North Polar Layered Deposits range in thickness from 1.6 m-16.0 m +/-1.4 m, and 6 of 13 marker beds are separated by ???25-35 m. Thin-layer sets have average layer separations of 1.6 m. These layer separations may account for the spectral-power-peaks found in previous brightness-profile analyses. Marker-bed layer thicknesses show a weak trend of decreasing thickness with depth that we interpret to potentially be the result of a decreased accumulation rate in the past, for those layers. However, the stratigraphic column reveals that a simple rhythmic or bundled layer sequence is not immediately apparent throughout the column, implying that the relationship between polar layer formation and cyclic climate forcing is quite complex. Copyright ?? 2010 by the American Geophysical Union.

  20. Cambrian-Ordovician Knox production in Ohio: Three case studies of structural-stratigraphic traps

    USGS Publications Warehouse

    Riley, R.A.; Wicks, J.; Thomas, J.

    2002-01-01

    The Knox Dolomite (Cambrian-Ordovician) in Ohio consists of a mixed carbonate-siliciclastic sequence deposited in a tidal-flat to shallow-marine environment along a broad continental shelf. Knox hydrocarbon production occurs in porous sandstone and dolomite reservoirs in the Copper Ridge dolomite, Rose Run sandstone, and Beekmantown dolomite. In Ohio, historical Knox exploration and development have been focused on paleogeomorphic traps within the prolific Morrow Consolidated field, and more recently, within and adjacent to the Rose Run subcrop. Although these paleogeomorphic traps have yielded significant Knox production, structural and stratigraphic traps are being largely ignored. Three Knox-producing pools demonstrate structural and stratigraphic traps: the Birmingham-Erie pool in southern Erie and southwestern Lorain counties, the South Canaan pool in northern Wayne County, and the East Randolph pool in south-central Portage County. Enhanced porosity and permeability from fractures, as evident in the East Randolph pool, are also an underexplored mechanism for Knox hydrocarbon accumulation. An estimated 800 bcf of gas from undiscovered Knox resources makes the Knox one of the most attractive plays in the Appalachian basin.

  1. Global Snow Mass Measurements and the Effect of Stratigraphic Detail on Inversion of Microwave Brightness Temperatures

    NASA Astrophysics Data System (ADS)

    Richardson, Mark; Davenport, Ian; Gurney, Robert

    2014-05-01

    Snow provides large seasonal storage of freshwater, and information about the distribution of snow mass as snow water equivalent (SWE) is important for hydrological planning and detecting climate change impacts. Large regional disagreements remain between estimates from reanalyses, remote sensing and modelling. Assimilating passive microwave information improves SWE estimates in many regions, but the assimilation must account for how microwave scattering depends on snow stratigraphy. Physical snow models can estimate snow stratigraphy, but users must consider the computational expense of model complexity versus acceptable errors. Using data from the National Aeronautics and Space Administration Cold Land Processes Experiment and the H