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1

Sequence stratigraphic framework of Neogene strata in offshore Nigeria  

SciTech Connect

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.

Pacht, J.A. [Seis Strat Services, Inc., Sugar Land, TX (United States); Bowen, B.E.; Hall, D.J. [Excalibur Consulting, Houston, TX (United States)] [and others

1996-08-01

2

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

Microsoft Academic Search

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

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

1996-01-01

3

Evaluation of untested stratigraphic traps in a Pleistocene Canyon-fill complex, offshore Louisiana  

SciTech Connect

Eugene Island Block 390, located approximately 100 mi offshore Louisiana was acquired by ARCO Oil and Gas Company in 1983 to test upper Pleistocene amplitude anomalies located on the faulted northwest flank of a diapiric salt structure. Although drilling has established the presence of oil and gas in the objective section, an attempt to delineate further reserve potential on the block was made by evaluating additional amplitude anomalies located downflank in an adjacent syncline. Seismic stratigraphic analysis indicates that the anomalies are located within the confines of an erosionally incised submarine canyon complex, approximately 3 mi wide and 500 ft deep. A number of high-amplitude events located in the upper part of the fill complex are interpreted to represent relatively coarser grained sandstone bodies, in contrast to the fine-grained material that represents the majority of the fill. In map view, these high-amplitude events are axially elongated, dip-trending bodies that were deposited laterally adjacent to one another. In the deepest parts of the ARCO 1 well, stratigraphically below their original objective, approximately 50 net ft of oil-saturated but very low-permeability silt and shale were encountered. Examination of the well location on seismic data indicates that the ARCO 1 well was drilled into in the canyon flank, updip from and laterally adjacent to the high-amplitude events. The interpretation is that the low permeability oil saturated sections seen in the ARCO 1 well is representative of the depositional transition into the seal facies. Therefore, the highest amplitude events located downdip of the ARCO 1 well are thought to represent stratigraphically trapped hydrocarbons reservoired within canyon-fill sands, an interpretation supported by positive amplitude vs. offset analysis results.

Geitgey, J.E. (ARCO Oil and Gas Co., Dallas, TX (USA))

1990-05-01

4

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

SciTech Connect

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.

Armentrout, J.M.; Smith-Rouch, L.S. [Mobil Exploration and Producing Technical Center, Dallas, TX (United States); Bowman, S.A. [Marco Polo Software, Inc., Houston, TX (United States)

1996-08-01

5

Stratigraphic test well, Nantucket Island, Massachusetts  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Massachusetts Water Resources Commission and the Nantucket Conservation Foundation, continuously cored 514 m of sediment and volcanic rock in a stratigraphic and water-quality test near the geographic center of Nantucket Island. Stratified sediments were divided texturally into three zones: the upper zone (0-128 m) contains mostly coarse sand and gravel; the middle zone (128-349 m) contains mostly silty clay and a few beds of sand and silt; and the lower zone (349-457 m) contains soft, unconsolidated, clayey sand. Below the lower zone, a saprolite, composed mostly of clay, grades abruptly downward at 470 m into partially altered basalt that extends to the bottom of the hole at 514 m. Calculations based on the Ghyben-Herzberg principle predicted a zone of freshwater 120-150 m thick. This principle is the theory of hydrostatic equilibrium between freshwater and more dense seawater in a coastal aquifer; it states that for each meter of ground-water elevation above sea level, the freshwater lens will depress the saltwater interface about 40 m below sea level. Freshwater or low-salinity brackish water was found in sediments far below the depth predicted by the Ghyben-Herzberg principle. These interstitial waters are probably relict ground water emplaced during times of low sea level during the Pleistocene. (Woodard-USGS)

Folger, David W.; Hathaway, J. C.; Christopher, R. A.; Valentine, P. C.; Poag, C. W.

1978-01-01

6

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

NASA Astrophysics Data System (ADS)

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.

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

2002-12-01

7

Sequence stratigraphic applications to deep-water exploration in the Makassar Strait, offshore East Kalimantan, Indonesia  

SciTech Connect

A sequence stratigraphic study was conducted to help evaluate the exploration potential of the Makassar PSC, offshore East Kalimantan, Indonesia. The PSC is on the present-day slope in water depths of 500-3000 ft and borders the large oil and gas fields of the Mahakam delta. The study provided important insights on reservoir distribution, trapping style, and seismic hydrocarbon indicators. Lowstand deposition on a slope modified by growth faulting and shale diapirism controlled reservoir distribution within the prospective late Miocene section. Three major lowstand intervals can be seismically defined and tied to deep-water sands in nearby wells where log character and biostratigraphic data support the seismic system tract interpretation. The three intervals appear to correlate with third-order global lowstand events and are consistent with existing sequence stratigraphic schemes for the shelf and upper slope in the Makassar area. Seismic mapping delineated lowstand features, including incised valleys and intraslope to basin-floor thicks. Regional information on positions of middle-late Miocene delta lobes and shelf edges, helped complete the picture for sand sources, transport routes, and depocenters.

Malacek, S.J.; Reaves, C.M.; Atmadja, W.S.; Widiantara, K.O. (Mobil Oil Indonesia, Jakarta (Indonesia))

1994-07-01

8

Stratigraphic framework, sedimentology and structural setting of Miocene-Pliocene sediments of the Abu Qir area, offshore Nile delta  

SciTech Connect

The offshore Nile delta contains significant gas resources which are currently undergoing both production and appraisal in the Abu Qir field and adjacent areas. The principal reservoir occurs in sandstones of the upper Abu Madi Member (upper Miocene), but excellent potential reservoirs exist in the lower Abu Madi Member (upper Miocene), Sidi Salem (middle-upper Miocene), and Moghra (middle Miocene) Formations. Gas is trapped in fault-bounded anticlinal structures sealed by shales of the Pliocene Kafr el Sheikh Formation. Early wells in the Abu Qir field revealed an apparently simple stratigraphic picture. More recently, however, drilled wells have revealed a more complex stratigraphic situation. Integrated biostratigraphic and sedimentologic studies demonstrate the existence of a fault block or horst structure beneath part of the field, giving rise to the observed stratigraphic complexity. Such a structure was not visible on seismic data due to inhibited reflection quality beneath the overlying Messinian anhydrite but has since been demonstrated by reprocessing and reinterpreting seismic data. The presence of a structural style of this type provides a new concept for hydrocarbon exploration in the area. Reservoir sandstones of the Abu Madi, Sidi Salem, and Moghra Formations are interpreted as sediment gravity flow deposits whose distribution is strongly influenced by syndepositional tectonics. This interpretation, supported by microfossil assemblages, provides important constraints for both reservoir modeling and further exploration.

Ince, D.M.; Deibis, S.; McSherry, A.; Seymour, W.P.

1988-08-01

9

Preliminary guidebook for identifying stratigraphic contacts at the Nevada Test Site.  

National Technical Information Service (NTIS)

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 miner...

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

1992-01-01

10

Milankovitch Cyclicity: A Tool for Determining the Stratigraphic Evolution of the Late Neogene Offshore Central California Margin  

NASA Astrophysics Data System (ADS)

Latest Miocene/Pliocene stratigraphy of the offshore central California margin records Milankovitch cyclicities on eccentricity through precessional time scales. Dating and correlation of Milankovitch cycles in the natural gamma ray logs of sediments from Ocean Drilling Program (ODP) Site 1016, 150 km offshore, to more proximal offshore oil wells provide new, higher-resolution sedimentation rates, refined mass accumulation rates of calcium carbonate and total organic carbon (TOC), identification of condensed sections, a suggested refinement of the ages of select Late Miocene radiolaria, as well as an overview of stratigraphic trends and geography along the paleomargin. This is the first application of astrochronology to dating the fine-grained, homogeneous sediments of the Late Neogene Monterey and Sisquoc formations of the petroliferous Santa Maria Basin. The relatively well-dated ODP Hole 1016A was used to create a high-resolution dating and correlation template for more proximal wells in the basin. Further applications and refinements of this template will aid in increasing knowledge of the architecture and stratigraphic history of the basin. The success of this project suggests that astrochronology is a valuable approach for correlating and dating formational and facies changes, and their lateral development across the basins of the California margin. A distinctive pattern in the gamma ray template of OPD Hole 1016A, dated from 5.2 to 4.8 Ma, was also found in eleven studied oil wells of the offshore Santa Maria Basin, permitting the determination of areal trends in sedimentation rates. Sedimentation rates increase towards the paleoshoreline, from 8 cm/ky 150 km from shore, to about 50 cm/ky in the medial wells, to about 90 cm/ky at the most proximal well. The rates also increase from NW to SE in the oil wells. The present depth of the 5.2 Ma horizon also increases toward the paleoshore, from about 245 m 150 km from shore, to about 1500 m in the medial wells to as much as 2600 m in the most proximal well. The depths also increase from NW to SE. Sedimentation rates at ODP Site 1016A, in general, decreased during the Late Neogene. From a high of 12-14 cm/ky circa 5.8 Ma, the sedimentation rate decreased to 2 to 3 cm/ky circa 2.6 Ma, with intermediate maxima of 11-12 cm/ky circa 4.9 to 5.1 Ma and 9 to 10 cm/ky circa 4.4 to 4.6 Ma. In spite of decreased linear sedimentation rates, the mass accumulation rate for calcium carbonate has generally increased from 5.8 to 2.6 Ma with a major peak at about 4.4 to 4.6 Ma. The mass accumulation rate for total organic carbon (TOC) shows a major peak at about 5.6 to 5.7 Ma, then a gradual increase to a second maximum about 4.3 to 4.4 Ma, a fairly sharp decrease from 4.3 to 4.0 Ma, and then a low, somewhat undulating rate to 2.6 Ma. The new higher-resolution MARs from this study show greater values before 3.5 Ma than previous works using earlier age scales. According to the new age scale, the dates suggested for the Miocene radiolarian stratigraphic markers at ODP Site 1016A are about 1.5 million years younger than the originally assigned ages.

Hill, P. S.; Behl, R. J.

2005-12-01

11

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

Microsoft Academic Search

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

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

1992-01-01

12

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

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)

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.

Gomez-Cabrera, Pedro Tomas

2003-10-01

14

Quantitative seismic attribute analysis using artificial neural networks and seismic stratigraphic interpretation of lower to middle Miocene sediments offshore New Jersey  

NASA Astrophysics Data System (ADS)

This study comprises two parts intended to improve understanding of the lower and middle Miocene depositional history of the New Jersey continental shelf. The first, lower Miocene-based part, aims to determine lateral variations in lithofacies between holes drilled by IODP Expedition 313 using seismic attributes and artificial neural networks. The second provides detailed seismic sequence stratigraphy of mid-Miocene successions. Neural networks are used in the first part to search for a relationship between seismic attributes and gamma log measurements of the lower Miocene section. Using this relationship, the networks generate 'pseudo gamma logs' that predict lateral changes in lithofacies based on accompanying changes in seismic attributes. A successful test of the technique is demonstrated using 3D seismic data and 6 closely-spaced gamma ray logs from the Denver Basin. A similar application to lower Miocene successions offshore NJ is unsuccessful, most likely due to an insufficient number of wells, complexity of lithofacies variations between wells up to 12 km apart, and/or an incorrect selection of attributes. In the second part, candidate sequence boundaries are identified in a grid of high-resolution, densely spaced profiles. In addition to a more detailed history than derived from prior studies, this part reveals previously unreported records of sediment erosion and possible global climate influence on the middle Miocene stratigraphic evolution offshore New Jersey. Eleven candidate sequence boundaries, three not documented by previous studies, are identified. System tract positions of each sequence are determined, while only one transgressive system tract and no lowstand fans are observed. Age estimates based on published studies show that the 11 mid Miocene sequences reported here span the interval between ˜11.8-12.9 Ma, suggesting an average interval between each of 100 kyr. Clinoform rollovers prograded SE during the development of the oldest sequence of the study area beginning at a time that coincides with a major shift in ?18O towards heavier values (represented by Mi4) and at about the time of the permanent East Antarctic ice sheet development. Grain size distribution of the prograding clinoforms is predicted by extrapolating IODP Expedition 313’s lithostratigraphic analysis of lower Miocene succession.

Karakaya, Sarp

15

Constructing Stratigraphic Relationships Using Secondary Craters: A Lunar Test Case  

NASA Astrophysics Data System (ADS)

Secondary cratering is a possible contaminant of small crater distributions used to date young terrains in the Solar System. As such, much attention has been paid to identifying the effect of the secondary population on the cratering record of various bodies. Our technique utilizes 100m resolution circular polarization ratio (CPR) maps generated from 2.38 GHz Arecibo radar data of the lunar South Pole to distinguish secondary craters from small primaries at large distances from the primary impact. High levels of CPR are indicative of blocky ejecta tails and can be used not only to identify secondaries in this "far field” regime, but can also indicate the associated primary crater by the tail direction. We apply this method to a region on the floor of Newton-A crater ( 60 km diameter), where our refined counts identify 56 secondary craters with diameters above 400m (43.8% of the total population) associated with the primary crater Tycho (85 km diameter)—some 1000 km to the north. In addition to providing information on the relative importance of secondary and primary craters at small diameters, this method of secondary crater identification provides valuable information about the terrains on which they are emplaced. Secondary craters associated with a single primary event form simultaneously, therefore serving as a convenient layer around which stratigraphic relationships can be constructed—particularly if the age of the primary is well constrained. For extensive secondary networks, the semi-global reach of this layer provides a way to compare in a standardized way terrain units separated by thousands of kilometers. As a demonstration of this technique, we employ a combination of crater morphology and CPR tail analysis to determine the ages of features on the floor of Newton-A relative to the layer of Tycho secondaries present there. Funding by NASA's Planetary Astronomy program is acknowledged.

Wells, Kassandra; Campbell, D. B.; Campbell, B. A.; Carter, L. M.

2008-09-01

16

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

Microsoft Academic Search

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.

Robert B. Hunter; Timothy S. Collett; Ray Boswell; Brian J. Anderson; Scott A. Digert; Gordon Pospisil; Richard Baker

2011-01-01

17

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

Microsoft Academic Search

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

Kelly Rose; Ray Boswell; Timothy Collett

2011-01-01

18

Neogene and Quaternary geology of a stratigraphic test hole on Horn Island, Mississippi Sound  

USGS Publications Warehouse

During April and May, 1991, the U.S. Geological Survey (USGS) drilled a 510-ft-deep, continuously cored, stratigraphic test hole on Horn Island, Mississippi Sound, as part of a field study of the Neogene and Quaternary geology of the Mississippi coastal area. The USGS drilled two new holes at the Horn Island site. The first hole was continuously cored to a depth of 510 ft; coring stopped at this depth due to mechanical problems. To facilitate geophysical logging, an unsampled second hole was drilled to a depth of 519 ft at the same location.

Gohn, Gregory S.; Brewster-Wingard, G. Lynn; Cronin, Thomas M.; Edwards, Lucy E.; Gibson, Thomas G.; Rubin, Meyer; Willard, Debra A.

1996-01-01

19

Test evaluates high-volume ESP application offshore Mexico  

Microsoft Academic Search

An electric submersible pump (ESP) test, although shorter than hoped for, indicated that artificial lift with ESPs had potential for replacing gas-lift operations, offshore Mexico. Petroleos Mexicanos (Pemex) recently preformed this test of a high-volume (10,000 b\\/d) ESP in the Akal reservoir of the Cantarell field, northeast Marina Region in the Gulf of Mexico. In the Marine Region, gas lift

S. G. Almazo; G. Riling

1998-01-01

20

Development of LiDAR measurements for the German offshore test site  

Microsoft Academic Search

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

A. Rettenmeier; M. Kühn; M. Wächter; S. Rahm; H. Mellinghoff; B. Siegmeier; L. Reeder

2008-01-01

21

Selected stratigraphic contacts for drill holes in LANL use areas of Yucca Flat, NTS (Nevada Test Site)  

Microsoft Academic Search

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. Several changes have been made to the

S. L. Jr. Drellack; A. P. Cavazos

1987-01-01

22

Selected stratigraphic contacts for drill holes in LANL (Los Alamos National Laboratory) use areas of Yucca Flat, NTS (Nevada Test Site)  

Microsoft Academic Search

This report is a compilation of selected stratigraphic contacts in drill holes in areas of Yucca Flat, Nevada Test Site (NTS), used by the Los Alamos National Laboratory (LANL). Data presented for each drill hole includes the following: (1) hole name; (2) total depth (TD) of drill hole at completion of drilling; (3) depth below surface to selected stratigraphic contacts;

S. L. Jr. Drellack; A. P. Cavazos

1986-01-01

23

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

USGS Publications Warehouse

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.

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

2011-01-01

24

Quantification and modelling of the distorsion of the stratigraphic architecture of the syn-sedimentary infill of a normal fault (offshore Congo)  

Microsoft Academic Search

We characterized the influence of a normal growth fault upon the stratigraphic architecture of the syn-sedimentary infill, in the case of a structure located along the West African margin, in terms of (1) variations in time and space of the accommodation (space available for sedimentation) and (2) distorsion of the geometry and timing of depositional sequences. To achieve this with

C. Robin; D. Rouby; F. Guillocheau; D. Granjeon; R. Bouroullec; S. Raillard

2003-01-01

25

Sequence-stratigraphic significance of Miocene to Pliocene glauconite-rich layers, on- and offshore of the US Mid-Atlantic margin  

Microsoft Academic Search

Glauconite is generally agreed to be a reliable indicator of low sedimentation rate, but little systematic work has been done to specify the role of glauconite in a sequence-stratigraphic framework. Ocean Drilling Program Leg 174A recovered a good record of late Tertiary sediments along the shelf edge of the New Jersey US Atlantic margin, and glauconite was present in many

L. C. Harris; B. M. Whiting

2000-01-01

26

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

USGS Publications Warehouse

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.

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

2011-01-01

27

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

USGS Publications Warehouse

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.

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

28

Quantification and modelling of the distorsion of the stratigraphic architecture of the syn-sedimentary infill of a normal fault (offshore Congo)  

NASA Astrophysics Data System (ADS)

We characterized the influence of a normal growth fault upon the stratigraphic architecture of the syn-sedimentary infill, in the case of a structure located along the West African margin, in terms of (1) variations in time and space of the accommodation (space available for sedimentation) and (2) distorsion of the geometry and timing of depositional sequences. To achieve this with a dataset made up of a 3-D seismic survey and well logs, we used sequence stratigraphy to (i) define a detailed stratigraphic framework, (ii) quantify the rates of vertical displacements from accommodation variations measurements, and, (iii) characterize the geometry of depositional sequences across the fault. We determined 2 orders of depositional sequences: the genetic units sets (0.5-2 Ma) resulting from the vertical stacking of genetic units. Correlation of time lines is established from the vertical stacking of genetic units. We measured accommodation variations for time steps corresponding to half cycles of genetic units sets (0.2 to 1 Ma). The difference of accommodation across the fault measures the subsidence rate (few tens to few hundreds m/Ma). Genetic unit sets are thicker in the subsiding area and the inversion of trend of the genetic unit sets from progradation to retrogradation (Flooding Surface) or from retrogradation to progradation (Maximum Flooding Surface) may be delayed or advanced. We show, based on a stratigraphic simulation, that the observed stratigraphic and time distortion of genetic units sets can be numerically reproduced using subsidence rates and cycle of sea level variations similar to the ones measured in the studied area.

Robin, C.; Rouby, D.; Guillocheau, F.; Granjeon, D.; Bouroullec, R.; Raillard, S.

2003-04-01

29

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

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.

Montagnier, P.; Rossi, T. (Elf Nigeria, Lagos (Nigeria)); Clergeat, B.; Dall'astam, W.F. (Elf Aquitaine Production, Paris (France))

1996-01-01

30

Underwater Inspection/Testing/Monitoring of Offshore Structures.  

National Technical Information Service (NTIS)

Requirements for underwater inspection of offshore structures and the techniques and tools to conduct such inspection vary widely from country-to country. The purpose of this six month study was: (1) to identify and describe all actual or potential underw...

1978-01-01

31

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)

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.

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

2013-12-01

32

Downhole well log and core montages from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope  

USGS Publications Warehouse

The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was an integral part of an ongoing project to determine the future energy resource potential of gas hydrates on the Alaska North Slope. As part of this effort, the Mount Elbert well included an advanced downhole geophysical logging program. Because gas hydrate is unstable at ground surface pressure and temperature conditions, a major emphasis was placed on the downhole-logging program to determine the occurrence of gas hydrates and the in-situ physical properties of the sediments. In support of this effort, well-log and core data montages have been compiled which include downhole log and core-data obtained from the gas-hydrate-bearing sedimentary section in the Mount Elbert well. Also shown are numerous reservoir parameters, including gas-hydrate saturation and sediment porosity log traces calculated from available downhole well log and core data. ?? 2010.

Collett, T. S.; Lewis, R. E.; Winters, W. J.; Lee, M. W.; Rose, K. K.; Boswell, R. M.

2011-01-01

33

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...

34

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)

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.

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

2007-12-01

35

Subsalt risk reduction using seismic sequence-stratigraphic analysis  

Microsoft Academic Search

Several recent projects involving detailed seismic-sequence stratigraphic analysis of existing wells near subsalt prospects in the south additions of the offshore Louisiana area in the Gulf of Mexico have demonstrated the utility of using seismic sequence-stratigraphic analysis to reduce risk when drilling subsalt plays. First, the thick section of sediments that was thought to be above and below the salt

Wornardt; W. W. Jr

1994-01-01

36

Expression and modelling of stratigraphic sequence distortion  

Microsoft Academic Search

This study describes the lateral variability of stratigraphic sequences under changing conditions of subsidence and\\/or sediment supply. Changes in sediment supply, subsidence and absolute sea-level result in at least three modes of distortion of a depositional sequence. Our study of a case history from offshore West Africa, together with numerical analysis, provides insights as to how changes in subsidence and

C. Robin; D. Rouby; D. Granjeon; F. Guillocheau; P. Allemand; S. Raillard

2005-01-01

37

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

SciTech Connect

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.

Boswell, R.M.; Hunter, R. (ASRC Energy Services, Anchorage, AK); Collett, T. (USGS, Denver, CO); Digert, S. (BP Exploration (Alaska) Inc., Anchorage, AK); Hancock, S. (RPS Energy Canada, Calgary, Alberta, Canada); Weeks, M. (BP Exploration (Alaska) Inc., Anchorage, AK); Mt. Elbert Science Team

2008-01-01

38

Development of LiDAR measurements for the German offshore test site  

NASA Astrophysics Data System (ADS)

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.

Rettenmeier, A.; Kühn, M.; Wächter, M.; Rahm, S.; Mellinghoff, H.; Siegmeier, B.; Reeder, L.

2008-05-01

39

Secondary Craters as Stratigraphic Markers: GIS-Based Program Development and Performance Testing Using the Secondaries of Zunil Crater, Mars  

Microsoft Academic Search

The pervasive occurrence of secondary crater chains across multiple geologic terrains on planetary surfaces elevates their potential utility as stratigraphic markers. However, current approaches that link secondaries to their parent (source) craters are qualitative and vulnerable to over-simplification. Herein, we present the developmental status and operational performance of a GIS-based computer program that analyzes the spatial relationship of secondary craters

R. A. Nava; J. A. Skinner

2009-01-01

40

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

USGS Publications Warehouse

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.

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

2011-01-01

41

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

USGS Publications Warehouse

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.

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

2007-01-01

42

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

SciTech Connect

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 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 TOUGHþHYDRATE 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 (3.3–3.9 ?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.

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

43

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

SciTech Connect

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.

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

1996-04-01

44

Damage-detection monitoring method for offshore platforms is field-tested  

SciTech Connect

There is a clear need to develop new methods for condition monitoring and inspection of offshore platforms. Two key reasons for this are the unreliability and the high cost of visual inspection-currently the most commonly used method. Among the inspection and monitoring methods now available, those based on vibration analysis seem to hold the greatest promise. A joint effort by two French firms has resulted in field-testing two new methods on a living quarters platform in the Arabian Gulf. This work describes the concepts, equipment, and operating procedures developed, and the significant results obtained. Full-scale experiments using vibro-detection and modal analysis, as described, have demonstrated these techniques possess considerable capability for purposes of structural integrity monitoring and potential as design aids.

Crohas, H.; Lepert, P.

1982-02-22

45

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

NASA Astrophysics Data System (ADS)

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 fault’s interaction with the San Andreas and San Gregorio faults, and may require the reevaluation of the Point Reyes fault’s seismic hazard potential.

Stozek, B.

2010-12-01

46

Teaching with Stratigraphic Profiles  

ERIC Educational Resources Information Center

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)

Stefanich, Greg P.

1974-01-01

47

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

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.

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

2011-01-01

48

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

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.

Laura A Stern;Thomas D Lorenson;John C Pinkston

2011-01-01

49

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

SciTech Connect

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.

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

2013-07-01

50

Identification of third-order (approx. 10{sup 6} yrs) and fourth-order (approx. 10{sup 5}/10{sup 4} yrs) stratigraphic cycles in the South Addition, West Cameron Lease Area, Louisiana offshore  

SciTech Connect

In the highly explored South Addition of the West Cameron Lease Area, Louisiana offshore, interpretation of a six-mile ({approx}10 km) seismic section across a single intraslope basin yielded 20 sediment packages. Several interpretive tools were necessary. Seismic stratigraphy indicated that the shallower zone was an outer shelf marked by 8 major sea level oscillations. In the portion between 1 and 3 seconds, seismic stratigraphy and paleontology led to the interpretation of depositional environments such as upper slope, and paleobathymetrically deeper intervals with descent through the section. The intraslope basin, while small, may be viewed as a micro-continental margin. Each sea level oscillation cycle apparently made a distinct progradational unit, decipherable in the seismic data. Fourth order cycles have been provisionally interpreted, throughout most of the entire 3.7 second section. Such precision is possible only in explored basins with excellent seismic data. The sequence thickness showed a seven-fold variability, from 0.08 to 0.58 seconds. The shallower section, deposited along an outer shelf, has an average individual sequence thickness of 0.13 seconds. Individual seismic sequences in the deeper section, interpreted to have been deposited on an upper slope, have average thicknesses of 0.25 seconds. The thinner sequences of the shallower section are compatible with the notion that the outer shelf was a bypass zone during a glacial epoch. The thicker sequences of the deeper section are the result of deposition onto an aggrading upper slope within an intraslope basin during a highstand.

Lowrie, A.; Meeks, P. [Specialty Office Services, Waveland, MS (United States); Hoffman, K. [Dynamics Graphics, Houston, TX (United States)

1996-09-01

51

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

SciTech Connect

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.

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

2009-09-01

52

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

SciTech Connect

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.

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

2011-06-01

53

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

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.

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

2011-01-01

54

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

USGS Publications Warehouse

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.

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

2011-01-01

55

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

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.

Wrege, Beth M.; Jen, Philip S.

2004-01-01

56

Gas geochemistry of the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: implications for gas hydrate exploration in the Arctic  

USGS Publications Warehouse

Gases were analyzed from well cuttings, core, gas hydrate, and formation tests at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, drilled within the Milne Point Unit, Alaska North Slope. The well penetrated a portion of the Eileen gas hydrate deposit, which overlies the more deeply buried Prudhoe Bay, Milne Point, West Sak, and Kuparuk River oil fields. Gas sources in the upper 200 m are predominantly from microbial sources (C1 isotopic compositions ranging from ?86.4 to ?80.6‰). The C1 isotopic composition becomes progressively enriched from 200 m to the top of the gas hydrate-bearing sands at 600 m. The tested gas hydrates occur in two primary intervals, units D and C, between 614.0 m and 664.7 m, containing a total of 29.3 m of gas hydrate-bearing sands. The hydrocarbon gases in cuttings and core samples from 604 to 914 m are composed of methane with very little ethane. The isotopic composition of the methane carbon ranges from ?50.1 to ?43.9‰ with several outliers, generally decreasing with depth. Gas samples collected by the Modular Formation Dynamics Testing (MDT) tool in the hydrate-bearing units were similarly composed mainly of methane, with up to 284 ppm ethane. The methane isotopic composition ranged from ?48.2 to ?48.0‰ in the C sand and from ?48.4 to ?46.6‰ in the D sand. Methane hydrogen isotopic composition ranged from ?238 to ?230‰, with slightly more depleted values in the deeper C sand. These results are consistent with the concept that the Eileen gas hydrates contain a mixture of deep-sourced, microbially biodegraded thermogenic gas, with lesser amounts of thermogenic oil-associated gas, and coal gas. Thermal gases are likely sourced from existing oil and gas accumulations that have migrated up-dip and/or up-fault and formed gas hydrate in response to climate cooling with permafrost formation.

Lorenson, T. D.; Collett, T. S.; Hunter, R. B.

2011-01-01

57

Offshore industry  

SciTech Connect

Worldwide offshore mobile drilling rig activity is described with details on rig orders, construction, installation and costs, and on supply and auxiliary vessels used with offshore rigs. Tabulated data are presented on the number of offshore rigs working at sites in both the eastern and western hemispheres. In 1980 the total number of drilling units increased to 306 from 70 in 1979. (LCL)

Heil, G.

1981-04-01

58

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

SciTech Connect

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.

Weideborg, M.; Vik, E.A.; Oefjord, G.D.; Kjoennoe, O. [Aquateam-Norwegian Water Technology Centre A/S, Oslo (Norway)

1997-02-01

59

Coupling thermo-mecanical simulation and stratigraphic modelling: impact of lithosphere deformation on stratigraphic architecture of passive margin basins.  

NASA Astrophysics Data System (ADS)

The aim of this study is to revise the view of the long-term stratigraphic trends of the Atlantic-type passive margins to include the impact of the coupling between the lithosphere deformation and the surface processes. However, modeling coupling lithosphere deformation and surface processes usually address large-scale deformation processes, i.e. they cannot resolve the stratigraphic trend of the simulated basins. On the other hand, models dedicated to stratigraphic simulation do not include these feedbacks of erosion/sedimentation on deformation processes. The recent development of a numerical modeling tool, coupling the thermal and flexural evolution of the lithosphere and including the (un)loading effects of surface processes in 3D (Flex3D; J. Braun), allows us to propose a new procedure to investigate, in 3D, the evolution of passive margins, from the scale of the lithosphere to the detailed stratigraphic architecture, including syn- and post-rift phases and onshore and offshore domains. To do this, we first simulate the syn-rift phase of lithosphere stretching by thermo-mechanical modeling (Sopal, R. Huismans). We use the resulting lithosphere geometry as input of the 3D flexural modeling to simulate the post-rift evolution of the margin. We then use the resulting accumulation and subsidence histories as input of the stratigraphic simulation (Dionisos, D. Granjeon) to model the detailed stratigraphic architecture of the basin. Using this procedure, we evaluate the signature of various boundary conditions (lithosphere geometries and thermal states, stretching distributions, surface processes efficiencies and drainage organization) in the uplift/subsidence and denudation histories as well as in the stratigraphic architectures of the associated sedimentary basins. We apply the procedure to the case study of the passive margins bounding the Southern Africa plateau, for which we have compiled data constraining the thermal history, the terrigeneous sediment accumulations, and the long term stratigraphic architectures.

Rouby, Delphine; Huismans, Ritske; Braun, Jean; Rohais, Sebastien

2013-04-01

60

Coupling Thermo-Mecanical Simulation and Stratigraphic Modelling: Impact of Lithosphere Deformation on Stratigraphic Architecture of Passive Margin Basins  

NASA Astrophysics Data System (ADS)

The aim of this study is to revise the 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. However, modeling coupling lithosphere deformation and surface processes usually address large-scale deformation processes, i.e. they cannot resolve the stratigraphic trend of the simulated basins. On the other hand, models dedicated to stratigraphic simulation do not include these feedbacks of erosion/sedimentation on deformation processes. The recent development of a numerical modeling tool, coupling the thermal and flexural evolution of the lithosphere and including the (un)loading effects of surface processes in 3D (Flex3D; J. Braun), allows us to propose a new procedure to investigate, in 3D, the evolution of passive margins, from the scale of the lithosphere to the detailed stratigraphic architecture, including syn- and post-rift phases and onshore and offshore domains. To do this, we first simulate the syn-rift phase of lithosphere stretching by thermo-mechanical modeling (Sopal, R. Huismans). We use the resulting lithosphere geometry as input of the 3D flexural modeling to simulate the post-rift evolution of the margin. We then use the resulting accumulation and subsidence histories as input of the stratigraphic simulation (Dionisos, D. Granjeon) to model the detailed stratigraphic architecture of the basin. Using this procedure, we evaluate the signature of various boundary conditions (lithosphere geometries and thermal states, stretching distributions, surface processes efficiencies and drainage organization) in the uplift/subsidence and denudation histories as well as the stratigraphic architecture of the associated sedimentary basins. We apply the procedure to the case study of passives margins surrounding the West African craton, for which we have compiled data constraining the denudation and accumulation history, and the long term stratigraphic architectures.

Rouby, D.; Huismans, R. S.; Braun, J.

2013-12-01

61

Offshore Technology  

NSDL National Science Digital Library

Offshore Technology is a Web site specifically geared for the offshore oil and gas industry. The highlight of the site is the Industry Projects link, which gives information about offshore drilling projects from around the world. Sites are categorized geographically and include description of the project, information on the geology of the area, drilling history of the site, wellhead platform, pipeline information, and much more. Other links on the main page include an A to Z listing of contractors and suppliers, exhibition and conference information, and other helpful resources for the offshore drilling professional and researcher.

62

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

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

63

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)

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.

Mahaney, William C.; Dohm, James M.

2011-07-01

64

Eighteenth annual offshore technology conference. Volume 1  

SciTech Connect

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.

Not Available

1986-01-01

65

Question of offshore oil  

Microsoft Academic Search

The following four papers were presented: the value of offshore oil; the environmental impact of offshore drilling; social benefit\\/cost analysis of offshore drilling; and the appropriate pace of offshore drilling. Commentary and response followed each presentation. (LK)

1976-01-01

66

Ice interaction with offshore structures  

SciTech Connect

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.

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

1988-01-01

67

Geologic evolution of a Pliocene-Pleistocene salt-withdrawal minibasin: Eugene Island Block 330, offshore Louisiana  

Microsoft Academic Search

The spatial and temporal distributions of reservoir sands are documented within the context of an evolving Plicoene-Pleistocene salt-withdrawal shelf minibasin. The Eugene Island Block 330 field, a giant oil and gas field in offshore Louisiana, is contained within the minibasin. Based on the stratigraphic and structural analyses, we present a sequence-stratigraphic and tectonic-stratigraphic model for reservoir prediction in complex shelf

L. L. Alexander; P. B. Flemings

1995-01-01

68

Stratigraphic Units in Las Vegas Valley, Nevada  

NASA Astrophysics Data System (ADS)

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.

Donovan, D.

2013-12-01

69

High Resolution Magnetostratigraphy Susceptibility (MS) and Gamma Radiation (GR) Measurements from Three Coeval Upper Cretaceous Stratigraphic Sequences in Colorado: Testing MS and GR Variations Arising from Detrital Components in Variably Weathered Marine Sedimentary Rocks (Invited)  

NASA Astrophysics Data System (ADS)

We have measured the magnetic susceptibility(MS) and gamma radiation (GR) for three Upper Cretaceous marine sedimentary sequences that span the Cenomanian-Turonian (C-T) boundary exposed as part of the Western Interior Seaway in Central Colorado. The purpose of this study was three fold: (1) to evaluate the combined potential of MS and GR as a correlation tool using well-studied sequences that have been previously correlated based on high-resolution lithostratigraphy, (2) to evaluate the effect of differential weathering on MS and GR values, and (3) to evaluate how their relationship with each other changes. This work includes sampling of the moderately weathered Global Boundary Stratotype Section and Point (GSSP) for the C-T boundary that is exposed in a railroad cut near Pueblo, CO. A nearby (~1 km) coeval section in an old road cut, where weathering is pronounced, was also sampled, as was fresh material through the C-T boundary interval from a core drilled ~40 km to the west of Pueblo (the USGS#1 Portland Core). MS was measured in the laboratory at LSU on samples collected at ~5 cm intervals from each of these sequences. GR was measured in the field at ~5 cm intervals on the two outcrop sequences, using a portable GR spectrometer. In addition, the GR also was measured on samples collected for MS measurement, using a laboratory-based Germanium detector. It is argued that both MS and GR data sets are controlled by detrital fluxes into the marine environment, although the effect of weathering, if any, on these parameters when exposed in outcrop, is not well documented. In addition, these parameters are controlled by different detrital components that may be derived from different sources, or be differentially concentrated within the marine system. Here we report the results of a number of experiments designed to evaluate how the MS and GR data sets co-vary, and to test their usefulness as correlation tools in stratigraphically. We have also examined the effects of varying magnitudes of weathering on these stratigraphic relationships. Of great interest to us has been to evaluate if, and how well these data sets record climate cycles, and how the MS and GR data are affected by weathering, if at all. The results of this work will be discussed in our presentation.

Ellwood, B. B.; Tomkin, J. H.; Wang, W.

2010-12-01

70

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

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.

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

2003-01-01

71

Summary of hydrologic testing in Tertiary limestone aquifer, Tenneco offshore exploratory well--Atlantic OCS, lease-block 427 (Jacksonville NH 17-5)  

USGS Publications Warehouse

A summary of hydrologic testing in an offshore oil-test well (LB427) drilled for Tenneco, Inc., 55 miles east of Fernandina Beach, Florida, is presented. The interval tested (1,050 to 1,070 feet below sea level) is in a calcarenite that is equivalent to the Ocala Limestone (late Eocene) of onshore Florida and South Georgia. At this site the Ocala forms the highly productive Tertiary limestone aquifer system of the southeastern United States. Pressure-head measurements indicate an equivalent freshwater head of 24 to 29 feet above sea level. These pressure-head measurements and an earlier one made in the nearby JOIDES J- I hole are the only hydraulic head determinations to date in the offshore extensions of any of the aquifers underlying the Atlantic coastal plain. A drill-stem test recovered water samples containing about 7,000 milligrams per liter chloride. However, seawater used in the drilling process apparently contaminated the samples and the formation water is considered slightly fresher. The head and salinity data from the Tenneco well suggest that the sampled interval lies in the transition zone between fresh and seawater in the limestone aquifer. These data, when viewed with similar data from JOIDES J-I, show the transition zone to slope very slightly landward. The interface position is probably intermediate between a position compatible with present-day heads and a position compatible with predevelopment heads.

Johnston, Richard H.; Bush, Peter W.; Krause, Richard E.; Miller, James A.; Sprinkle, Craig L.

1982-01-01

72

In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope  

USGS Publications Warehouse

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

Lee, M. W.; Collett, T. S.

2011-01-01

73

X-ray CT Observations of Methane Hydrate Distribution Changes over Time in a Natural Sediment Core from the BPX-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well  

SciTech Connect

When maintained under hydrate-stable conditions, methane hydrate in laboratory samples is often considered a stable and immobile solid material. Currently, there do not appear to be any studies in which the long-term redistribution of hydrates in sediments has been investigated in the laboratory. These observations are important because if the location of hydrate in a sample were to change over time (e.g. by dissociating at one location and reforming at another), the properties of the sample that depend on hydrate saturation and pore space occupancy would also change. Observations of hydrate redistribution under stable conditions are also important in understanding natural hydrate deposits, as these may also change over time. The processes by which solid hydrate can move include dissociation, hydrate-former and water migration in the gas and liquid phases, and hydrate formation. Chemical potential gradients induced by temperature, pressure, and pore water or host sediment chemistry can drive these processes. A series of tests were performed on a formerly natural methane-hydrate-bearing core sample from the BPX-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, in order to observe hydrate formation and morphology within this natural sediment, and changes over time using X-ray computed tomography (CT). Long-term observations (over several weeks) of methane hydrate in natural sediments were made to investigate spatial changes in hydrate saturation in the core. During the test sequence, mild buffered thermal and pressure oscillations occurred within the sample in response to laboratory temperature changes. These oscillations were small in magnitude, and conditions were maintained well within the hydrate stability zone.

Kneafsey, T.J.; Rees, E.V.L.

2010-03-01

74

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

75

Offshore oil: an overview  

Microsoft Academic Search

This report provides an assessment of the current status of offshore activity with particular reference to (1) trends in offshore production, and (2) the intensity and location of exploration drilling, this being an essential precondition for any future increase in offshore crude production. The report includes in-depth profiles of those non-OPEC nationa where the chances of discovering further recoverable offshore

Manners

1980-01-01

76

Design, manufacturing and tests of first cryogen-free MgB2 prototype coils for offshore wind generators  

NASA Astrophysics Data System (ADS)

Although renewable sector has started to take advantage of the offshore wind energy recently, the development is very intense. Turbines reliability, size, and cost are key aspects for the wind industry, especially in marine locations. A superconducting generator will allow a significant reduction in terms of weight and size, but cost and reliability are two aspects to deal with. MgB2 wire is presented as one promising option to be used in superconducting coils for wind generators. This work shows the experimental results in first cryogen-free MgB2 prototype coils, designed according to specific requirements of TECNALIA's wind generator concept.

Sarmiento, G.; Sanz, S.; Pujana, A.; Merino, J. M.; Iturbe, R.; Apiñaniz, S.; Nardelli, D.; Marino, I.

2014-05-01

77

Experimental stress analysis in massive offshore structures  

Microsoft Academic Search

Immense steel and concrete platforms are being used for offshore oil production. Loads in these fixed-rigs, in floating-rig components and in production pipelines are being measured with strain gages and transducers.Certain of these offshore structures and typical testing which has been performed are discussed, including some using environmentally protected weldable strain gages.

Douglas G. Ritchie

1977-01-01

78

Application of TIMS data in stratigraphic analysis  

NASA Technical Reports Server (NTRS)

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.

Lang, H. R.

1986-01-01

79

Underbalanced drilling benefits now available offshore  

SciTech Connect

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.

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

1997-05-01

80

Some debatable problems of stratigraphic classification  

NASA Astrophysics Data System (ADS)

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 c

Gladenkov, Yury

2014-05-01

81

Offshore oil prospects improve  

NASA Astrophysics Data System (ADS)

The issues, prospects, and environmental concerns about drilling for offshore oil and gas are being seen in a different light than at any other time during the past decade. Exploration drilling on offshore locations is proceeding at a high rate, and environmental concerns, while recognized as real, appear to be a lot less worrisome than might have been predicted a decade ago. Part of the reason for the changes in levels of concern results from the close monitoring programs that have been in effect for the past few years. Paul R. Ryan of the Woods Hole Oceanographic Institution recently described exploration activities on Georges Bank: “We now have the results of the first year of monitoring, and, although eight wells are considered a minimal observational test, there were no biological changes in the benthic community that could be attributed to drilling activity.” (Oceanus, 26, 2, 1983). The U.S. Geological Survey studied the Georges Bank drilling activities as well. Barium from drilling muds was detected at the sites, but in decreasing concentrations at distances away from drilling rigs. There was no evidence that the discharges caused biological changes. According to Ryan: “Postdrilling concentrates of barium were found to be within the range of predilling concentrations measured at other locations on the Bank. Concentrations of other metals measured were low and characteristic of unpolluted, coarse-grained sediment in other Continental Shelf areas.”

82

BIOMODULE: a Java program to help model and interpret the stratigraphic record  

NASA Astrophysics Data System (ADS)

A combination of a stratigraphic simulation package (STRATA) and an evolutionary-ecological model (BIOSTRAT) can be used to simulate the distribution of species within a sequence stratigraphic framework. BIOMODULE is an extension of this model approach in that it facilitates the visualization and interpretation of those simulations and their input data. Environmental factors (e.g., sea-level changes or sedimentation rates) and ecological factors (preferred water depth, depth tolerance, abundance) that determine the spatial and temporal distribution of species are easily and quickly investigated. In addition, BIOMODULE can be used to compile the stratigraphic first and last appearances of those species and export them into available graphic correlation software packages (Conop9 and GraphCor). This can be used to test the graphic correlation technique and investigate its accuracy and precision under a range of different conditions (e.g., different stratigraphic architectures and sampling densities) since the true correlation of the different sections is already known.

Herrmann, Achim D.; Patzkowsky, Mark E.; Holland, Steven M.

2003-02-01

83

Offshore yearbook, 1987  

SciTech Connect

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.

Not Available

1987-01-01

84

Stratigraphic control of flow and transport characteristics.  

PubMed

Ground water flow and travel time are dependent on stratigraphic architecture, which is governed by competing processes that control the spatial and temporal distribution of accommodation and sediment supply. Accommodation is the amount of space in which sediment may accumulate as defined by the difference between the energy gradient and the topographic surface. The temporal and spatial distribution of accommodation is affected by processes that change the distribution of energy (e.g., sea level or subsidence). Fluvial stratigraphic units, generated by FLUVSIM (a stratigraphic simulator based on accommodation and sediment supply), with varying magnitudes and causes of accommodation, were incorporated into a hydraulic regime using MODFLOW (a ground water flow simulator), and particles were tracked using MODPATH (a particle-tracking algorithm). These experiments illustrate that the dominant type of accommodation process influences the degree of continuity of stratigraphic units and thus affects ground water flow and transport. When the hydraulic gradient is parallel to the axis of the fluvial system in the depositional environment, shorter travel times occur in low-total accommodation environments and longer travel times in high-total accommodation environments. Given the same total accommodation, travel times are longer when sea-level change is the dominant process than those in systems dominated by subsidence. PMID:17257334

Edington, Dwaine; Poeter, Eileen

2007-01-01

85

Stratigraphic control of flow and transport characteristics.  

PubMed

Ground water flow and travel time are dependent on stratigraphic architecture, which is governed by competing processes that control the spatial and temporal distribution of accommodation and sediment supply. Accommodation is the amount of space in which sediment may accumulate as defined by the difference between the energy gradient and the topographic surface. The temporal and spatial distribution of accommodation is affected by processes that change the distribution of energy (e.g., sea level or subsidence). Fluvial stratigraphic units, generated by FLUVSIM (a stratigraphic simulator based on accommodation and sediment supply), with varying magnitudes and causes of accommodation, were incorporated into a hydraulic regime using MODFLOW (a ground water flow simulator), and particles were tracked using MODPATH (a particle-tracking algorithm). These experiments illustrate that the dominant type of accommodation process influences the degree of continuity of stratigraphic units and thus affects ground water flow and transport. When the hydraulic gradient is parallel to the axis of the fluvial system in the depositional environment, shorter travel times occur in low-total accommodation environments and longer travel times in high-total accommodation environments. Given the same total accommodation, travel times are longer when sea-level change is the dominant process than those in systems dominated by subsidence. PMID:17087754

Edington, Dwaine; Poeter, Eileen

2006-01-01

86

Stratigraphic Columns Across Southern Western Interior  

NSDL National Science Digital Library

This website depicts stratigraphic columns of exposed rocks in southwestern regions of the United States. A general explanation of symbols used in the columns is provided for reference, and the columns indicate rock type, formation names and geologic time periods. The areas covered include the Grand Canyon, central and southern Arizona, southern Utah and Nevada, and western New Mexico and Colorado.

Blakey, Ronald

87

Petroleum geology of the mid-Atlantic continental margin, offshore Virginia  

USGS Publications Warehouse

The Baltimore Canyon Trough, a major sedimentary basin on the Atlantic continental shelf, contains up to 18 km of Mesozoic and Cenozoic strata. The basin has been studied extensively by multichannel common depth point (CDP) seismic reflection profiles and has been tested by drilling for hydrocarbon resources in several places. The Mesozoic and Cenozoic strata contained in the basin were deposited in littoral to bathyal depositional settings and contain immature to marginally mature oil-prone and gas-prone kerogen. The more deeply buried strata of Early Mesozoic age are more likely to be thermally mature than are the younger strata with respect to hydrocarbon generation, but contain terrestrially derived coaly organic matter that would be prone to yield gas, rather than oil. An analysis of available CDP seismic reflection data has indicated that there are several potential hydrocarbon plays in the area offshore of Virginia. These include: (1) Lower Mesozoic synrift basins that appear similar to those exposed in the Appalachian Piedmont, (2) a stratigraphic updip pinchout of strata of Early Mesozoic age in the offshore region near the coast, (3) a deeply buried paleoshelf edge, where seismic reflectors dip sharply seaward; and (4) a Cretaceous/Jurassic shelf edge beneath the present continental rise. Of these, the synrift basins and Cretaceous/Jurassic shelf edge are considered to be the best targets for exploration. ?? 1989.

Bayer, K. C.; Milici, R. C.

1989-01-01

88

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

NASA Astrophysics Data System (ADS)

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.

Yamamoto, K.; Fujii, T.

2013-12-01

89

Offshore oil drilling  

Microsoft Academic Search

The accelerated offshore leasing plan proposed by the US government will involve huge areas containing marine biological resources of considerable economic, ecological, social, and aesthetic value. Offshore drilling and onshore refining\\/processing facilities can mar the scenic beauty of an area and gradually change seabed and water conditions, while always posing the threat of a major oil spill. Environmentalists currently disagree

Hileman

1981-01-01

90

Magnetic polarity stratigraphy and stratigraphic completeness  

NASA Astrophysics Data System (ADS)

A fundamental limiting factor in the precision of magnetostratigraphic correlation is stratigraphic completeness. Sadler [1981] has suggested a method by which the expected completeness of any given stratigraphic section can be calculated given the thickness, duration, and depositional environment. The technique is probabilistic and requires the investigator to specify a meaningful short-term time scale at which completeness is to be estimated. For magnetostratigraphy, the short-term time scale is defined by the duration of the polarity chron or other polarity feature of interest. Sadler's method allows the probability of observing such features to be quantified. It is a useful tool for evaluating the reliability of magnetostratigraphic correlations and for judging between alternative correlations.

May, Steven R.; Butler, Robert F.; Roth, Frances A.

91

Subsurface sequence stratigraphic correlation using well logs  

NSDL National Science Digital Library

Students are given hard copies of a subsurface section containing gamma and resistivity logs of nine closely-spaced (well distance varies from 1 to 3 km) wells from Delaware Basin, southeast New Mexico for an interval of ~ 200 m clastic succession of Morrow sandstone of Pennsylvanian age. Core sedimentology of one of these wells is also provided. Students' task is to correlate the well logs to generate a stratigraphic cross-section of the area using sequence stratigraphic approach. As the data are from Delaware Basin, southeast New Mexico, student should first gather the knowledge of regional setting of the basin, with a particular emphasis to the paleo-eustasy. (Clue: in Delaware Basin, Morrow sandstones deposited in a low accommodation settings with high-amplitude fluctuations of sea-level.) When correlating the well logs students should start with the well which has lithological information. Students should try to correlate the mudstones first. The two most prominent sequence stratigraphic surfaces with comparatively higher correlation-length are 'sequence boundary' produced by pronounced fall of sea-level, and 'maximum flooding surface' generated at the time of highest stand of sea-level. Students should pay particular attention to incised-valley-fill deposits. After completing the correlation, students should check whether their correlation satisfy our prevailing ideas of sequence stratigraphy and stratal packaging. Student should prepare a brief description of overall depositional environments and sea-level history of the area substantiating their subsurface correlation. By doing this exercise, students will learn how to apply sequence stratigraphic principles in interpreting subsurface data, particularly from well logs.

Gani, M. R.

92

Applications for concrete offshore  

SciTech Connect

The report collects and summarizes the various proposals for development offshore which have in common the use of concrete as the main structural material, and where possible, indicates their relative feasibility. A study encompassing such diverse schemes as offshore windmills, concrete LNG carriers, hydrocarbon production platforms and floating airports cannot be completely exhaustive on each subject, so references to sources of further information have been given wherever possible. Details of individual projects and proposals are included for Power plants, Hydrocarbon production platforms, Concrete ships, Storage systems and industrial plants, Subsea systems, Offshore islands, Coastal works and Other concrete structures.

Not Available

1982-01-01

93

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

Microsoft Academic Search

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,

William C. Mahaney; James M. Dohm

2011-01-01

94

Offshore Pipeline Failures.  

National Technical Information Service (NTIS)

An overview of current concerns in the regulation of offshore pipelines is presented along with tabulated summaries of pipeline failure causes, failure prevention techniques, and pipeline monitoring and early intervention techniques. A database of over 10...

R. D. Woodson

1990-01-01

95

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)

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).

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

2013-12-01

96

3D Stratigraphic Modeling of Central Aachen  

NASA Astrophysics Data System (ADS)

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 René Lefebvre (2005) 3D geologic

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

2010-05-01

97

American Association of Stratigraphic Palynologists, Inc. (AASP)  

NSDL National Science Digital Library

The American Association of Stratigraphic Palynologists, Inc. (AASP) was established in 1967 "to promote the science of palynology in academia and industry." Visitors can discover scholarship opportunities and awards. The Biographies and Histories of Palynology link offers a growing collection of materials about many of the prominent scientists in the field of palynology, which is the branch of science concerned with the study of pollen, spores, and similar palynomorphs, living and fossil. By viewing a Microsoft PowerPoint presentation, students can learn about the science of palynology. Researchers can find information on a variety of conferences and meetings as well as on the publications produced by AASP.

98

Seismic stratigraphy of the offshore Nile delta  

SciTech Connect

The seismic stratigraphy of the offshore Nile delta has been established using a 10,000-km Merlin reprocessed regional seismic database. This paper focuses on the Neogene interval in which three major seismic super sequences have been recognized. The oldest (super sequence A) is a thick sheet unit of middle Miocene age composed of marine shales and sandstones, affected in places by shale diapirism. The upper super sequence, of Pliocene age (C), is characterized by progradation complicated by both slumping and faulting. These sediments represent deposits from the present Nile delta system, a relatively recent event. Between super sequences A and C lies a thin upper Miocene - lowermost Pliocene unit (super sequence B). This unit can be divided into three sequences, the upper and lower of which (Abu Madi and Oawasim Formations, respectively) are characterized by widespread channeling. The intermediate Messinian sequence, commonly evaporitic, may also be associated with channeling episodes. Potential hydrocarbon plays exist in all three super sequences, and varied trapping mechanisms may be invoked. Dip closures are associated with both rollover on listric normal faults and shale diapirism. Stratigraphic trap potential involves both truncation of C beneath B, occasionally associated with severe angular unconformity, and super sequence B channeling. The Abu Madi channel-fill sand bodies form the primary exploration target. Despite only 12 offshore wells drilled, there have already been gas discoveries (Abu Qir field, Naf-1 well) which, together with recent changes in Egyptian hydrocarbon legislation, make this region an attractive exploration province.

Kilenyi, T.; Trayner, P.; Doherty, M.; Jamieson, G.

1988-08-01

99

Regional method to assess offshore slope stability.  

USGS Publications Warehouse

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

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

1986-01-01

100

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

Microsoft Academic Search

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

Drellack; S. L. Jr

1988-01-01

101

Getting offshoring right.  

PubMed

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

Aron, Ravi; Singh, Jitendra V

2005-12-01

102

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

Microsoft Academic Search

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 ~900km\\/h, the kinetic

William C. Mahaney; James M. Dohm

2011-01-01

103

Wave slamming on offshore structures  

NASA Astrophysics Data System (ADS)

Experimental and theoretical work on the slamming of circular cylinders is surveyed. Data are included from controlled drop tests. The influence of inclined impact and beam dynamics on the resulting stresses is calculated for a wide range of wave conditions. The statistical distributions of the estimated stresses are analyzed to provide data for the calculation of slamming loads on fixed offshore structures using simple formulas in which the slamming coefficients incorporate both the member dynamics and the sea wave statistics. Slamming coefficients and associated stress calculation methods are presented for extreme values and fatigue damage. These may also be used for slamming during jacket launching. A film of wave slam was also produced.

Miller, B. L.

1980-03-01

104

Offshore and Arctic operations, 1991  

SciTech Connect

This book contains the following topics: Design advantages of Beta Titanium 38-644 springs in outfield applications, Caissin support structure (CSS), Optimizing operations for offshore platform fabrication, Concrete strength evaluation of offshore structures.

Urquhart, R.G. (Maple Gas Corp. (US)); Tawfik, A.S. (Brown and Root USA, Inc. (US))

1991-01-01

105

Marine Pollution from Offshore Chemicals.  

National Technical Information Service (NTIS)

The report analyses the influencing impact on the marine environment caused by the various chemical effluents from the offshore drilling and production. The offshore chemicals used at the Statfjord and Ekofisk fields on the Norwegian Continental Shelf are...

O. Bjoerseth G. Halmoe R. Romslo T. Syvertsen

1986-01-01

106

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

NASA Astrophysics Data System (ADS)

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.

Yan, Pin; Liu, Hailing

2004-12-01

107

Paleontological Events: Stratigraphic, Ecologic, and Evolutionary Implications  

NASA Astrophysics Data System (ADS)

A most active area of modern paleontology concerns the causes and consequences of global mass extinction events. Fueled by wide public interest in extinction of the dinosaurs and debate among geologists over the causes of this event, paleontologists have scrutinized the geologic record of extinction events. Volume after volume has addressed these prominent extinction events. Far less study, and an order of magnitude less paper, have been devoted to the causes of local and regional paleontological events such as local extinctions and incursions even though they are far more common and can be equally dramatic.Many sedimentary geologists have observed horizons of marine sedimentary rocks unusually enriched in fossil remains. However, few of us stop to consider their significance.Paleontological Events: Stratigraphic, Ecologic, and Evolutionary Implications showcases 20 state-of-the-art papers that explore the causes of short-term and longer-term bioevents that have left behind remarkable paleontological records.

Bralower, Timothy J.

108

Kurten Field: find another by stratigraphic prospecting  

SciTech Connect

The Woodbine Kurten Field is a stratigraphic sand lens surrounded by shale. This field is a significant discovery in Brazos, Grimes and Madison counties, Texas. Structure plays only a minor role in oil entrapment. The sand was deposited in a structural and topographic low demonstrated by comparing maximum pay sand thickness with a computer trend surface residual thick derived from Austin to BUDA isopach map. Sand migration southward down the east Texas trough was deflected westward by the Angelina-Caldwell flexure and caught in a sag at the Kurten Field locality. The higher Madisonville nose to elevation at Madisonville and on the Angelina flexure only serves to limit sand deposition. Purposely seeking sags near a sand-shale regional boundary may result in many porosity POD type fields in the future.

Pavlovic, R.

1980-01-01

109

Offshore rectenna feasbility  

NASA Technical Reports Server (NTRS)

A preliminary study of the feasibility and cost of an offshore rectenna to serve the upper metropolitan east coast was performed. A candidate site at which to build a 5 GW rectenna was selected on the basis of proximity to load centers, avoidance of shipping lanes, sea floor terrain, and relocated conditions. Several types of support structures were selected for study based initially on the reference system rectenna concept of a wire mesh ground screen and dipoles each with its own rectifier and filter circuits. Possible secondary uses of an offshore rectenna were examined and are evaluated.

Freeman, J. W.; Hervey, D.; Glaser, P.

1980-01-01

110

GENERAL GEOLOGY OF THE MID-TERTIARY BLOCK 889 FIELD AREA, OFFSHORE MUSTANG ISLAND, TEXAS  

Microsoft Academic Search

The structural and stratigraphic architecture of the Block 889 field area, offshore Mustang Island, Texas, was defined by the integration of 3-D seismic, wireline logs, and engineering data. The area has produced 145 Bcf (billion cubic feet) of gas and 3 MMbbl (million barrels) of con- densate since the mid-1960's. Shale-withdrawal controlled the structural evolution of the area. Three growth

Ramón H. Treviño; Robert G. Loucks; L. Frank Brown; Randy L. Remington

111

Detecting cycles in stratigraphic data: Spectral analysis in the presence of red noise  

NASA Astrophysics Data System (ADS)

We discuss the detection of cyclic signals in stratigraphic `time series' using spectral methods. The dominant source of variance in the stratigraphic record is red noise, which greatly complicates the process of searching for weak periodic signals. We highlight two issues that are more significant than generally appreciated. The first is the lack of a correction for `multiple tests' - many independent frequencies are examined for periods but using a significance test appropriate for examination of a single frequency. The second problem is the poor choice of null hypothesis used to model the spectrum of non-periodic variations. Stratigraphers commonly assume the noise is a first-order autoregressive process - the AR(1) model - which in practice often gives a very poor match to real data; a fact that goes largely unnoticed because model checking is rarely performed. These problems have the effect of raising the number of false positives far above the expected rate, to the extent that the literature on spatial stratigraphic cycles is dominated by false positives. In turn these will distort the construction of astronomically calibrated timescales, lead to inflated estimates of the physical significance of deterministic forcing of the climate and depositional processes in the pre-Neogene, and may even bias models of solar system dynamics on very long timescales. We make suggestions for controlling the false positive rate, and emphasize the value of Monte Carlo simulations to validate and calibrate analysis methods.

Vaughan, S.; Bailey, R. J.; Smith, D. G.

2011-12-01

112

Reservoir characterization of the Miocene Starfak and Tiger Shoal fields, offshore Louisiana through integration of sequence stratigraphy, 3-D seismic, and well-log data  

NASA Astrophysics Data System (ADS)

Many "mature" Gulf of Mexico (GOM) fields, due to their structurally and stratigraphically complex nature, possess significant remaining resources. Such is the case in the Starfak and Tiger Shoal fields, offshore Louisiana. In these fields, forty hydrocarbon reservoirs occur in a regressive Miocene-age succession that comprises 10 third-order and at least 58 fourth-order sequences. Reservoir-scale heterogeneity is controlled by the nature and distribution of sedimentary facies and is usually below the resolution of current subsurface seismic sampling. Sequence-stratigraphic analysis helps to improve predictions of spatial and temporal reservoir heterogeneity. This study addresses the application of the correlation between petrophysical properties (PP) (e.g., effective porosity and shale volume) and seismic attributes (SA) within a high-frequency sequence-stratigraphic framework to identify untapped reservoir compartments in the two offshore Louisiana fields. Synthetic modeling of the seismic data showed that the vertical resolution of the seismic is approximately 12 ms. The relief on the fourth-order sequence boundary (SB) is below seismic resolution. A new method of mapping fourth-order SBs was developed. This method is based on the ability to image planiform morphology along the SB that can be depicted from a sequence of 4-ms-thick stratal slices. This method was successfully applied in the study area, and showed increased resolution when compared to two other mapping methods (manual tracking and proportional slicing). Three methods were tested to correlate SA with PP: (1) direct correlation between SAs and PPs through regression analysis, (2) seismic inversion, and (3) probabilistic neural network (PNN). Among the three methods, the PNN proved to be the best technique. Four uncontacted compartments targeting incised-valley sands in genetic sequence 30 were identified upon analyzing the inverted Vshale volume created using PNN method. Starfak and Tiger Shoal are typical of mature shelf-bound fields in the GOM, with long and sustained production histories. Structural and stratigraphic heterogeneities present opportunities for reserve-growth potential if an improved process for mapping of geologic complexity can be unraveled.

Badescu, Adrian Constantin

113

Stratigraphic and structural interpretation with 3-D seismic coherence  

Microsoft Academic Search

3-D seismic discontinuity is useful for identifying faults, stratigraphic features and the relationship between them. This paper covers the application of coherence technology to three basins; the Gulf of Mexico, the North Sea, and the Ardmore Basin of Oklahoma. In the Gulf of Mexico, 3-D coherence data may be used to simultaneously view faults and stratigraphic features and therefore see

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

1996-01-01

114

Offshore Wind Energy Systems  

ERIC Educational Resources Information Center

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)

Musgrove, P.

1978-01-01

115

Copenhagen Offshore Wind 2005  

Microsoft Academic Search

The planning, the special development work, and the installation of the foundations for the offshore wind parks North Hoyle in the Irish Sea and Scroby Sands in the North Sea are described. The wind parks comprise each 30 2 MW Vestas V 80 turbines. In both wind parks monopile foundations were used. They were placed in open sea in tidal

Niels-Erik Ottesen Hansen

116

The state of offshore  

SciTech Connect

In this book, the author explains the factors behind state involvement in offshore petroleum activities. From his analysis of government workings in Great Britain and Norway, he concludes that state intervention is determined by complex interactions among government officials, economic interests, and environmental pressures.

Nelson, B.F.

1991-01-01

117

Wave - Wind Offshore Systems  

Microsoft Academic Search

The 160 MW Horns Rev offshore wind farm has provided valuable inputs for the planning of substantially larger plants. The lessons learnt include problems associated with deployment, issues concerning operation and maintenance, the need for wind forecasts and grid interaction issues. As many such installations are being planned at water depths of 10 m or so lead one to conjecture

T. Geetha; Boby George; V. Jayashankar

118

Offshore Space Center (offshore launch site)  

NASA Technical Reports Server (NTRS)

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.

Harvey, D. G.

1980-01-01

119

Offshore Space Center (offshore launch site)  

NASA Astrophysics Data System (ADS)

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.

Harvey, D. G.

1980-07-01

120

Stratigraphic evolution of paleozoic erathem, northern Florida  

SciTech Connect

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.

Coleman, J.L. Jr.

1985-02-01

121

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)

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.

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

2012-12-01

122

Offshore arctic structure  

SciTech Connect

An apparatus is disclosed for minimizing the horizontal forces on an offshore arctic structure due to ice movement. The structure includes a base portion, sloped side walls and a smooth, unobstructed portion. The structure is substantially submerged in a body of water with the top portion at or near the water surface permitting floating ice sheets which strike the side walls to flex slightly upward and advance along and over the structure without substantially destroying the overall integrity of ice sheet. In this manner, the horizontal forces on the structure resulting from the ice sheet are minimized due to the elimination of a crushing failure mode of the ice sheet commonly associated with conventional offshore arctic structures.

Weiss, R.

1983-08-09

123

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

NASA Astrophysics Data System (ADS)

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. To do this, we developed a new numerical procedure simulating interactions between lithosphere deformation and (un)loading effects of surface processes (erosion/sedimentation) in 3D with a special attention to the stratigraphic architecture of the associated sedimentary basins. We first simulate the syn-rift phase of lithosphere stretching by thermo-mechanical modeling. We then use the resulting 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 resulting accumulation and subsidence histories as input of the stratigraphic simulation to model the detailed stratigraphic architecture of the basin. We tested this procedure using synthetic examples of lithosphere stretching based on different rheologies of the lithosphere (i.e. strength of the lower crust) in the cases of narrow or ultrawide rifting. We determined the stratigraphic expression of the conjugate margins and show that they differ in terms of long-term stratigraphic trends, erosion/accumulation and lithological distribution in space and time. 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).

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

2014-05-01

124

Arctic offshore platform  

SciTech Connect

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.

Bhula, D.N.

1984-01-24

125

Offshore finds inspire optimism  

SciTech Connect

The author reviews the oil market in Australia and the Pacific. Some of the highlights are: Australia/Pacific drilling hit 308 in 1987; about 300 seen for 1988; Offshore holds action in New Zealand, while onshore Papua makes news; Reduced taxes, relaxed foreign investment rules aid Aussie development work; Four solid solid discoveries made in Papua's Southern Highlands in 18 months; and Austrialia and New Zealand enact industry degregulation measures.

Not Available

1988-08-01

126

Building an Idealized Stratigraphic Sequence â Clastic Shoreline Example  

NSDL National Science Digital Library

The purpose of this exercise is to guide students through the process of constructing a stratigraphic sequence based on understanding relationships between the production of space and filling that space with sediment.

Little, William W.

127

The stratigraphic filter and bias in measurement of geologic rates  

USGS Publications Warehouse

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.

Schumer, Rina; Jerolmack, Douglas; McElroy, Brandon

2011-01-01

128

Offshore wind modelling and forecast  

Microsoft Academic Search

Offshore wind power projects are critically reliant on accurate wind resources assessment and large offshore wind farm operations require timely weather forecast. Most often, however, the offshore measurement is scarce and a conventional 6 hourly large scale weather model outputs with a typical resolution 0.5º x 0.5º is rather limited in application. The lack of measurement and the need for

Jiri Beran; Barbara Jimenez; Abha Sood

129

Offshore~WMEP - Monitoring offshore wind energy use  

Microsoft Academic Search

Offshore wind energy use is commonly suggested to play an important role in future electricity supply. However, long-term experience with thousands of onshore wind turbines explicitly hint on possible barriers for a save, efficient, economic and user friendly supply relying on offshore wind energy. A national German programme shall on the one hand support the wind energy branch improving technology

P. Lyding; S. Faulstich; B. Hahn; D. Callies

130

Stratigraphic Evidence of Sorted Bedform Evolution  

NASA Astrophysics Data System (ADS)

An examination of inner shelf sediments off Tairua on the north east coast of New Zealand provides stratigraphic evidence of the manner in which `sorted bedforms' or `rippled scour depressions' evolve and the oceanographic or geological conditions control their growth. Side-scan sonar, seismics and 15 vibracores (6 m long), interpreted in the context of wider field studies including swath mapping, seabed sampling and tripod deployments, provide a picture of the surface features and internal architecture of a Holocene sand body, along with detail of the alternating bands of coarse and fine sedimentary units interpreted as sorted bedforms. The coarse fraction is typically shell hash with some rock fragments. The coarse units are thin and typically the thickness of a bedform or two, while the associated fine sand units can be several meters thick. The boundaries between the units are typically distinct, but can be transitional. The coarse units are massive, show upward fining, or are just abruptly coarser at the base, reflecting differing modes of deposition such as settling from suspension, partial reworking of the coarse layer of lateral movements of large ripple over the bed, and the lateral back-and-forth oscillations of the boundaries of the units that we mapped at the surface. The stratigraphy reveals a picture of continual and progressive sorting and the difference between the coarse sand units represents various stages in bedform evolution frozen in time by burial by fine sand. In contrast the fine sands are massive, or exhibit weak horizontal laminae of shell fragments about 1 sand grain thick. While the coarse units are generally well developed and contain little fine sand, we see some that have much higher sand content and may represent coarse units that failed to develop fully before burial. The occurrence of the coarse units is unrelated to the thickness of the unconsolidated Holocene, and there is no obvious layer of coarse source sediments lying at shallow depth below the coarse and fine sedimentary units. In fact the very old C14 dates returned from shell material in the coarse units of surficial sediments suggest that the coarse layers take a long time to accumulate and shell is reworked from older deposits to do this. We present evidence suggesting that the coarse units develop best in areas of low sediment supply. Numerical modeling may help explain these processes. The Foundation for Research, Science and Technology (contract C01X0401) and the Andrew W. Mellon Foundation supported this work.

Hume, T. M.; Coco, G.; Green, M. O.; Murray, B.; Trembanis, A.; McNinch, J.

2005-05-01

131

Offshore abandonment heats up  

SciTech Connect

This paper reviews the new concerns regarding the decommissioning of offshore oil platforms which are rapidly coming of age. It reviews the history of past removal operations and the public outcry which is now causing a reevaluation of this abandonment policy. It reviews the number of platforms which are rapidly approaching maturity on a global basis. It then goes on to costs involved in such removal operations. Finally, it reviews the new platform designs which should allow a much more cost effective decommissioning process for these future rigs.

NONE

1995-08-01

132

Offshore outlook: the American Arctic  

SciTech Connect

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.

Jahns, M.O.

1985-05-01

133

Offshore oil: Technology - and emotion  

Microsoft Academic Search

Drilling and search techniques used in the exploitation of off-shore oil reserves are discussed. An overview is given of major government policy statements regarding the use of the outer continental shelf for oil production. The risk of detrimental effects on the environment caused by oil spills from off-shore drilling or damage to benthic animals is considered.

K. O. Emery

1976-01-01

134

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

NASA Astrophysics Data System (ADS)

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.

Marok, Abbas; Reolid, Matías

2012-11-01

135

Towers for Offshore Wind Turbines  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

136

Stratigraphic controls on fluid and solute fluxes across the sediment-water interface of an estuary  

USGS Publications Warehouse

Shallow stratigraphic features, such as infilled paleovalleys, modify fresh groundwater discharge to coastal waters and fluxes of saltwater and nutrients across the sediment–water interface. We quantify the spatial distribution of shallow surface water–groundwater exchange and nitrogen fluxes near a paleovalley in Indian River Bay, Delaware, using a hand resistivity probe, conventional seepage meters, and pore-water samples. In the interfluve (region outside the paleovalley) most nitrate-rich fresh groundwater discharges rapidly near the coast with little mixing of saline pore water, and nitrogen transport is largely conservative. In the peat-filled paleovalley, fresh groundwater discharge is negligible, and saltwater exchange is deep (?1 m). Long pore-water residence times and abundant sulfate and organic matter promote sulfate reduction and ammonium production in shallow sediment. Reducing, iron-rich fresh groundwater beneath paleovalley peat discharges diffusely around paleovalley margins offshore. In this zone of diffuse fresh groundwater discharge, saltwater exchange and dispersion are enhanced, ammonium is produced in shallow sediments, and fluxes of ammonium to surface water are large. By modifying patterns of groundwater discharge and the nature of saltwater exchange in shallow sediments, paleovalleys and other stratigraphic features influence the geochemistry of discharging groundwater. Redox reactions near the sediment–water interface affect rates and patterns of geochemical fluxes to coastal surface waters. For example, at this site, more than 99% of the groundwater-borne nitrate flux to the Delaware Inland Bays occurs within the interfluve portion of the coastline, and more than 50% of the ammonium flux occurs at the paleovalley margin.

Sawyer, Audrey H.; Lazareva, Olesya; Kroeger, Kevin D.; Crespo, Kyle; Chan, Clara S.; Stieglitz, Thomas; Michael, Holly A.

2014-01-01

137

Intraslope basin reservoirs deposited by gravity-driven processes: Ship shoal and ewing banks areas, offshore Louisiana  

Microsoft Academic Search

Seismic facies and high-resolution biostratigraphic analysis provide a sequence stratigraphic framework for interpreting lateral distribution of sand-prone facies and reservoir connectivity in the Ship Shoal 351-358 to Ewing Bank 988 area, offshore Louisiana. The interval of interest is an isochron thick interpreted as a lowstand systems tract deposited at bathyal water depths within an intraslope-basin. This basin is approximately 50

J. M. Armentrout; S. J. Malecek; V. R. Mathur

1995-01-01

138

Intraslope basin reservoirs deposited by gravity-driven processes: Ship Shoal and Ewing Banks areas, offshore Louisiana  

Microsoft Academic Search

Seismic facies and high-resolution biostratigraphic analysis provide a sequence stratigraphic framework for interpreting lateral distribution of sand-prone facies and reservoir connectivity in the Ship Shoal 351-358 to Ewing Bank 988 area, offshore Louisiana. The interval of interest is an isochron thick interpreted as a lowstand systems tract deposited at bathyal water depths within an intraslope-basin. This basin is approximately 50

J. M. Armentrout; S. J. Malecek; V. R. Mathur; G. L. Neuder; G. M. Ragan

1996-01-01

139

Combined effect of tectonism, eustasy, and sediment supply on the depositional-sequence history of the western offshore, South Africa  

Microsoft Academic Search

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 km². Lower frequency second-order supercycles (5-10 Ma) are attributed to changes in

1991-01-01

140

Offshore production challenged  

SciTech Connect

The capability to produce oil fields from under 20,000 ft of water or below the thick and treacherous Arctic icepack are 2 of the breakthroughs that have been brought about by a quietly emerging technology. A scan of announcements by designers, contractors, operators, and manufacturers reveals that substantial research and development efforts are being undertaken to ease the task of bringing to market the energy resources trapped under presently inaccessible locations. As a result, entirely new breeds of permanent or temporary drilling/production systems are evolving, some of which could be scaled down to face still another challenge: the economic exploitation of marginal offshore fields, whose meager reserves do not justify development by conventional means. New offshore systems described include the mobile Arctic drilling system, the mobile concrete island drilling system, the base and independent deck platform, the buoyant tower, the semiflex floating station, the tension leg platform, the big buoy floating cylinder, and the Sea Plex retrievable drilling/production system.

Franco, A.

1983-10-01

141

Floating offshore structure  

SciTech Connect

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.

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

1985-05-28

142

Evaluation of offshore stocking of Lake Trout in Lake Ontario  

USGS Publications Warehouse

Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration targets.

Lantry, B. F.; O'Gorman, R.; Strang, T. G.; Lantry, J. R.; Connerton, M. J.; Schanger, T.

2011-01-01

143

Petroleum Systems of South Kara Basin: 3D stratigraphic simulation and basin modeling results  

NASA Astrophysics Data System (ADS)

Petroleum systems of South Kara Basin are still poorly studied and hydrocarbon resource estimates vary depending on geological models and understanding of the basin evolution. The main purpose of the regional studies of South Kara Basin was to produce a consistent model, which would be able to explain the existence of the fields discovered in the area as well as to determine the most favorable hydrocarbon accumulation zones in the study area for further exploration. In the study 3D stratigraphic simulation and basin modeling of South Kara Basin was carried out. The stratigraphic simulation results, along with geological, geophysical and geochemical data for the inland areas of Yamal and Gydan peninsulas and South Kara islands enabled to predict the lithological composition and distribution of source rocks, reservoirs and seals in the Kara Sea offshore area. Based on the basin modeling results hydrocarbon accumulations may occur in the reservoir facies of the wide stratigraphic range from Jurrasic to Cretaceous. The main source for the hydrocarbons, accumulated in the South Kara Basin Neocomian and Cenomanian reservoirs are the J3-K1 (the northward extension of Bazhenov Formation and its analogs of West Siberia), as well as J1 and probably J2 shales with predominantly marine type of kerogen (type II). Thermal and burial history restorations show that Lower Cretaceous (Aptian-Albian) sediments enriched with terrigenous organic matter (kerogen of type III) and containing coaly layers could not produce the hydrocarbon volumes to fill the giant Rusanovskoye and Leningradskoye gas-condensate fields as the K1 source rocks are not mature enough. The modeling results, in particular, suggest that the geologic conditions in the South Kara Basin are favorable for further discoveries of giant fields. Although gas accumulations are predominating in the basin, oil-and-gascondensate fields (not a pure oil fields though) with sufficient part of liquid hydrocarbons might be present in particular areas where the source rocks maturation was favorable. Further refining of the model will be possible as soon as new exploration wells will be drilled and new geological, geochemical and seismic data acquired.

Malysheva, S.; Vasilyev, V.; Verzhbitsky, V.; Ananyev, V.; Murzin, R.; Komissarov, D.; Kosenkova, N.; Roslov, Yu.

2012-04-01

144

A review of techniques for the estimation of magnitude and timing of exhumation in offshore basins  

NASA Astrophysics Data System (ADS)

Exhumation, the removal of overburden resulting from the vertical displacement of rocks from maximum burial depth, occurs at both regional and local scales in offshore sedimentary basins and has important implications for the prospectivity of petroliferous basins. In these basins, issues to be addressed by the petroleum geologist include, the timing of thermal 'switch-off' of source rock units, the compactional and diagenetic constraints imposed by the maximum burial depth of reservoirs (prior to uplift), the physical and mechanical characteristics of cap-rocks during and post-exhumation, the structural evolution of traps and the hydrocarbon emplacement history. Central to addressing these issues is the geoscientist's ability to identify exhumation events, estimate their magnitude and deduce their timing. A variety of individual techniques is available to assess the exhumation of sedimentary successions, but generic categorisation indicates that 'point' measurements of rock displacement, in the offshore arena, are made with respect to four frames of reference — tectonic, thermal, compactional or stratigraphic. These techniques are critically reviewed in the context of some of the exhumed offshore sedimentary basins peripheral to the Irish landmass. This review confirms that large uncertainty is associated with estimates from individual techniques but that the integration of seismic interpretation and regional stratigraphic data provides valuable constraints on estimates from the more indirect tectonic, thermal and compactional methods.

Corcoran, D. V.; Doré, A. G.

2005-10-01

145

Bahrain's offshore banking center  

SciTech Connect

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)

Gerakis, A.S.; Roncesvalles, O.

1983-01-01

146

Arctic and offshore research: Technology status report  

SciTech Connect

This report describes the state of technology relative to the production of oil and gas in the Arctic. It discusses the technical issues that warrant investigation, and focuses on the current Department of Energy supported activities. Major accomplishments during the last year include the following: The Arctic and Offshore Research Information System (AORIS) was planned with industry survey recommendations incorporated. It contains a directory of 85 Arctic databases, a bibliographic component of over 7,000 citations, and a data component of about 300 data sets on sea ice characteristics. Seven position, pressure, and temperature buoys were deployed on ice islands (up to 3 by 6 miles in size) drifting off Ellesmere Island. Ice island movement, as much as 340 miles southwest of the Ward Hunt Ice Shelf during the last 4 years, represents a potential hazard to Arctic offshore structures in the Alaskan Beaufort Sea. The redesigned Seafloor Earthquake Measurement System (SEMS II) was deployed near Shell's Ellen-Elly platforms, about 10 miles offshore of Long Beach, California. The SEMS monitored the July 1986 southern California earthquakes. This was the first time earthquakes were simultaneouslly monitored by sensors located on land, aboard offshore platforms, and beneath the seafloor. Sea spray ice bond shear strength to various structural and protective coatings has been determined. The polyethylene coating demonstrated the most potential for rapid shedding of spray ice by gravity loading. Measurements of temperatures and salinities were completed as part of a pilot test to (1) detect seasonal conditions at the water-seabed interface, and (2) determine how they influence permafrost growth in the coastal waters of the Beaufort Sea. The temperatures and computed freezing point data suggest that seasonal seabed freezing can occur most of the winter. 13 refs., 14 figs., 4 tabs.

Not Available

1988-01-01

147

Auditing offshore safety risk assessments  

SciTech Connect

Risk assessments submitted to support proposals for offshore operations must be audited to ensure conformance with regulating authorities' safety requirements. This paper outlines the approach adopted for auditing recent submissions to the U.K. Dept. of Energy for simultaneous drilling and production (SDP) with jackup rigs cantilevered over gas production platforms. The principles are valid for risk-assessment audits of other offshore installations.

Moss, T.R. (RM Consultants Ltd. (GB))

1990-10-01

148

Mixing offshore oil and politics  

Microsoft Academic Search

This article discusses the opposition of coastal states to offshore oil drilling and how this opposition is slowing the U.S. government's plans for offshore oil exploration. In 1983, it is cited that exploration of off-coastal-states drilling dropped to about 54% of what it was two years earlier, a reflection of both leasing problems and decreasing oil and natural gas prices.

1984-01-01

149

Sequence stratigraphic and genetic aspects of the Tournaisian \\  

Microsoft Academic Search

This study reports the results of interdisciplinary investigations of Tournaisian deposits from the German Rheinisches Schiefergebirge and provides a genetic and sequence stratigraphic interpretation. Microfacies and geochemical data confirm normal marine outer shelf to slope environments for the Lower Tournaisian Hangenberg Formation. In contrast, data from the condensed, phosphatic \\

Hendrik Siegmund; Jörg Trappe; Wolfgang Oschmann

2002-01-01

150

Stratigraphic and structural synthesis of the New England Orogen  

Microsoft Academic Search

It is difficult to determine the ages of thick stratigraphic units in different parts of the Tablelands Complex in New England, because of a scarcity of fossils and the effects of superposed deformations. Many problems disappear if it is assumed that the Silverwood Group is in part Lower Permian and that its Ordovician and Devonian fossils are in olistoliths derived

R. J. Korsch; H. J. Harrington

1981-01-01

151

Stratigraphic traps in Silurian lockport dolomite of Kentucky  

Microsoft Academic Search

The Lockport Dolomite has yielded commercial quantities of petroleum for nearly 100 years and continues to be an exploration target in eastern Kentucky. Reservoirs are largely confined to porous buildups and to erosional truncation along the Cincinnati arch. These stratigraphic traps developed under the influence of (1) sea level fluctuations, which controlled the development of reefal, skeletal-bank, and ooid-shoal facies

R. Smosna; J. M. Conrad; T. Maxwell

1989-01-01

152

Determination of Heat Capacity of Yucca Mountain Stratigraphic Layers.  

National Technical Information Service (NTIS)

The heat generated from the radioactive waste to be placed in the proposed geologic repository at Yucca Mountain, Nevada, will affect the thermal-hydrology of the Yucca Mountain stratigraphic layers. In order to assess the effect of the movement of reposi...

C. Lum J. E. Bean T. Hadgu

2006-01-01

153

Concept for Improved Crane Performance in Offshore Operations.  

National Technical Information Service (NTIS)

The joint Army/Navy Marine Corps Off-Shore Discharge of containership I and II (OSDOC I and II) Test/Evaluation exercises were conducted in 1970 and 1972, respectively, in order to explore through test and evaluation various techniques for unloading conta...

D. Dillon L. Bonde

1976-01-01

154

Stratigraphic characterization of the Anthropocene: a progress report  

NASA Astrophysics Data System (ADS)

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.

Zalasiewicz, Jan

2014-05-01

155

Interpretation of biostratigraphic data at a sequence stratigraphic scale  

SciTech Connect

Recent advances in sequence stratigraphic concepts provide a framework within which biostratigraphic data can be used in conjunction with other stratigraphic tools in an integrated approach to stratigraphic analysis. Sequence stratigraphic concepts suggest that lithologic sections are composed of a succession of unconformity-bounded units or sequences. These sequences can, in turn, be subdivided into systems tracts bounded by flooding surfaces or maximum flooding surfaces. Three systems tracts comprise a sequence: the lowstand or shelf margin systems tract at the base, followed by the transgressive systems tract, and the highstand systems tract. On continental margins with a discrete shelf/slope break, deep-sea submarine fans, shelf-margin deltas, and incised-valley fills characterize the lowstand systems tract. On ramp-like continental margin, the lowstand systems tract is characterized by basinally-isolated lowstand shorelines with or without preserved incised-valley feeder systems. The transgressive systems tract has backstepping shorelines and estuarine fill of incised valley systems. The highstand systems tract is has forestepping depositional systems and widespread floodplain development. A large amount of the structure in the stratigraphic distribution of fossils can be attributed to sequence architecture. This structure can be statistically delineated in terms of a hierarchy that is independent of both fossil group and geological age. The definition of [open quotes]biological analogs[close quotes] of systems tracts reduces the complexity of paleontological census data to a set of (1) internal characteristics within genetic units and (2) boundary conditions at stratal discontinuities. Different taxon groups should display unique and repeatable patterns within different systems tracts and at stratal discontinuities within a basin, providing a new perspective of paleontological data across a spectrum of applications in sequence characterization and correlation.

Goodman, D.K. (ARCO Oil Gas Company, Midland, TX (United States)); Posamentier, H.W. (ARCO Exploration and Production Technology, Plano, TX (United States))

1993-02-01

156

Offshore pollution prevention  

SciTech Connect

A complete system for removing oil from produced water and deck drain fluids in an offshore facility includes a surge settler which receives the produced water from a three-phase separator. In the surge settler, the produced water flows crosswise through a corrugated plate assembly to separate free oil and solids from the produced water. A portion of the produced water which is relatively free of solid particles (less than 50 microns) is then treated in a water washer with a portion which is relatively rich in solid particles further treated in a solids cleaner. In the water washer 90% or more oil droplets (less than 50 microns) is removed from the produced water and the relatively oil free water is then disposed by way of a skim pile. A portion of fluid from the water washer is further treated in a high efficiency skimmer. In the solids cleaner a conical corrugated plate arrangement having periodic agitation by sand cleaning eductors removes free oil from the solids rich portion of the fluid which is relatively rich in solid particles and passes a relatively oil free and solids rich portion to a skim pile for disposal. Drained fluids from exposed decks and elsewhere are supplied directly to the skim pile for oil removal prior to passage into the surrounding body of water.

Favret, U.B. Jr.

1984-01-31

157

Structure for offshore exploitation  

SciTech Connect

A structure is disclosed for use in exploiting arctic offshore areas where floating ice masses may be present. The structure is comprised of a floating hull having ice-breaking capabilities which is moored by a plurality of mooring means which extend vertically from a moonpool in the hull to the marine bottom directly under the hull. The mooring means comprises flexible lines, e.g. nylon, steel, or the like or rigid conduits, e.g. drill pipe. Means are provided within the moonpool for tensioning the mooring means to thereby draw the hull downward to a position below its normal buoyant position thereby substantially eliminating vertical heaving of the hull. When an ice mass contacts the hull, tension on the mooring means is relaxed to thereby allow the hull to rock upward against the ice thereby generating the forces necessary for the ice-breaking operation. Due to the present mooring means, the hull moves only a relatively short lateral distance in breaking an approaching ice mass. This is important in floating drilling operations. Further, if repair or replacement of a mooring means is required, this can be accomplished even when ice surrounds the hull since the mooring means are anchored directly below the hull and are easily accessible through the moonpool.

Gerwick, B.C. Jr.; Hatcher, S.J.

1984-02-28

158

Combination offshore drilling rig  

SciTech Connect

An offshore drilling rig is described for use in drilling into a formation below a body of water comprising a barge hull having a drilling slot extending inwardly from the peripheral boundary of the barge hull, means for supporting the barge hull in a position above the water, a cantilever structure mounted on the barge hull and movable horizontally with respect to such barge hull, the cantilever structure being so located relative to the drilling slot as to be movable horizontally into a position in vertical alignment with the drilling slot, a derrick and drilling machinery mounted to the cantilever structure and movable into a position above the drilling slot whereby well drilling operations may be conducted through the drilling slot, the cantilever structure also being movable horizontally to a position which locates the derrick and the drilling machinery outboard of the peripheral boundary of the barge hull, whereby a drilling operations may be conducted outside of the peripheral boundary of the barge hull, means mounted on the barge hull for moving the cantilever structure horizontally to different positions relative to the barge hull.

Lorenz, D.B.; Laid, J.S. II

1986-07-29

159

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

SciTech Connect

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.

Hamilton, D.S.; Holtz, M.H.; Yeh, J. (Univ. of Texas, Austin, TX (United States)) (and others)

1996-01-01

160

High-alloy materials for offshore applications  

SciTech Connect

High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion, hydrogen embrittlement, and stress-corrosion cracking (SCC) are presented. This paper also contrasts the range of mechanical properties available in precipitation-hardened materials with properties of cold-worked alloys.

Lemke, T.F.; Harris, J.A.

1983-05-01

161

76 FR 11503 - National Offshore Safety Advisory Committee; Vacancies  

Federal Register 2010, 2011, 2012, 2013

...specializing in the support, by offshore supply vessels or other vessels, of offshore mineral and oil operations including geophysical...and training related to offshore exploration and construction...specializing in offshore drilling. To be eligible,...

2011-03-02

162

76 FR 39410 - National Offshore Safety Advisory Committee; Vacancies  

Federal Register 2010, 2011, 2012, 2013

...specializing in the support, by offshore supply vessels or other vessels, of offshore mineral and oil operations including geophysical...representing construction of offshore exploration and recovery...specializing in offshore drilling; and, (e) One...

2011-07-06

163

Biozones, stratigraphic log correlation, and corresponding interpretation of paleoenvironments.  

NSDL National Science Digital Library

The 50-minute group-based activity for hundreds of students starts by constructing bio-zones for a given set of fossil ranges. Results are reviewed using a sequence of clicker questions to discuss the optimal biostratigraphic decisions, the necessary types of thinking, and how to articulate a concise yet complete textual description of corresponding biozones. A set of stratigraphic logs is then used to interpret changes in depositional environment across space and time. Students also decide (and justify decisions) on the optimal choice of fossils for use when interpreting variations in depositional environment. The final result is an interpreted geologic section based on stratigraphic and biostratigraphic data. This interpretive exercise is only three weeks into a first course on Earth and life through time, so guidance is provided using carefully designed question sequences posed using "clicker" (personal response system) and/or for individual or whole class discussion.

Jones, Francis

164

Stratigraphic record of Holocene coseismic subsidence, Padang, West Sumatra  

NASA Astrophysics Data System (ADS)

Stratigraphic evidence is found for two coseismic subsidence events that underlie a floodplain 20 km south of Padang, West Sumatra along the Mentawai segment (0.5°S-0.3°S) 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.

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

165

Stratigraphic studies: Part A: basalt stratigraphy of southern Mare Serenitatis  

USGS Publications Warehouse

Mare Serenitatis has long been noted for its conspicuous dark border (fig. 29-1). The Apollo 17 metric photographs traverse this border in southern Mare Serenitatis and show clearly superposition relationships among the mare and mare-related stratigraphic units. These photographs, together with full-Moon photographs, albedo measurements, and color information (table 29-I), provide the basis for a revised stratigraphic framework for these presumedly basaltic rocks (figs. 29-2 and 29-3). In contrast to most previous studies, we conclude that the darker units are older than lighter ones. Similar conclusions have been reached by Bryan and Adams (part C of sec. 30) and Boyce and Dial (part C of this section). The relatively light-colored central part of Mare Serenitatis is thought to represent the youngest basalt in the region; a very dark unit that includes the Apollo 17 landing site is one of the oldest.

Howard, K. A.; Carr, M. H.; Muehlberger, W. R.

1973-01-01

166

Sedimentology and stratigraphic development of the upper Nyalau Formation (Early Miocene), Sarawak, Malaysia: A mixed wave- and tide-influenced coastal system  

NASA Astrophysics Data System (ADS)

This work presents the first detailed facies analysis of the upper Nyalau Formation exposed around Bintulu, Sarawak, Malaysia. The Lower Miocene Nyalau Formation exposures in NW Sarawak represent one of the closest sedimentological outcrop analogues to the age equivalent, hydrocarbon-bearing, offshore deposits of the Balingian Province. Nine types of facies associations are recognised in the Nyalau Formation, which form elements of larger-scale facies successions. Wave-dominated shoreface facies successions display coarsening upward trends from Offshore, into Lower Shoreface and Upper Shoreface Facies Associations. Fluvio-tidal channel facies successions consist of multi-storey stacks of Fluvial-Dominated, Tide-Influenced and Tide-Dominated Channel Facies Associations interbedded with minor Bay and Mangrove Facies Associations. Estuarine bay facies successions are composed of Tidal Bar and Bay Facies Associations with minor Mangrove Facies Associations. Tide-dominated delta facies successions coarsen upward from an Offshore into the Tidal Bar Facies Association. The Nyalau Formation is interpreted as a mixed wave- and tide-influenced coastal depositional system, with an offshore wave-dominated barrier shoreface being incised by laterally migrating tidal channels and offshore migrating tidal bars. Stratigraphic successions in the Nyalau Formation form repetitive high frequency, regressive-transgressive cycles bounded by flooding surfaces, consisting of a basal coarsening upward, wave-dominated shoreface facies succession (representing a prograding barrier shoreface and/or beach-strandplain) which is sharply overlain by fluvio-tidal channel, estuarine bay or tide-dominated delta facies successions (representing more inshore, tide-influenced coastal depositional environments). An erosion surface separates the underlying wave-dominated facies succession from overlying tidal facies successions in each regressive-transgressive cycle. These erosion surfaces are interpreted as unconformities formed when base level fall resulted in deep incision of barrier shorefaces. Inshore, fluvio-tidal successions above the unconformity display upward increase in marine influence and are interpreted as transgressive incised valley fills.

Amir Hassan, Meor H.; Johnson, Howard D.; Allison, Peter A.; Abdullah, Wan Hasiah

2013-10-01

167

Geotechnics of Fixed Offshore Drilling Platforms.  

National Technical Information Service (NTIS)

Fixed offshore-structures are widely used for exploration and exploitation of undersea oil and gas resources. The object of this report is to survey the general geotechnical design principles and foundation technics of fixed offshore-structures. Additiona...

J. Toernqvist

1984-01-01

168

Tectono-stratigraphic interpretation, DBGS-114, Delaware Basin  

SciTech Connect

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.

Swift, D.B. [Texas Tech Univ., Midland, TX (United States); Reeves, J.J. [Univ. of Texas, Odessa, TX (United States)

1995-06-01

169

Paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks  

SciTech Connect

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.

Cecil, C.B. (Geological Survey, Reston, VA (USA))

1990-06-01

170

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

171

CHRONOS's Paleontological-Stratigraphic Interval Construction and Analysis Tool (PSICAT)  

NASA Astrophysics Data System (ADS)

The Paleontological-Stratigraphic Interval Construction and Analysis Tool (PSICAT) is a Java-based graphical editing tool for creating and viewing stratigraphic column diagrams from drill cores and outcrops. It is customized to the task of working with stratigraphic columns and captures data digitally as you draw and edit the diagram. The data and diagrams are captured in open formats, and integration with the CHRONOS system (www.chronos.org) will allow the user to easily upload their data and diagrams into CHRONOS. Because the data and diagrams are stored in CHRONOS, they will be accessible to anyone, anywhere, at any time. PSICAT is designed with a modular, plug-in-based architecture that will allow it to support a wide variety of functionality, tasks, and geoscientific communities. PSICAT is currently being developed for use by the ANDRILL project (http://www.andrill.org) on their upcoming drilling expeditions in Antarctica, but a general community version will be also available. PSICAT will allow unprecedented communication between Antarctica-based scientists and shore-based scientists, potentially allowing shore-based scientists to interact in almost real time with on-ice operations and data collection.

Reed, J. A.; Cervato, C.; Fielding, C. R.; Fils, D.

2005-12-01

172

Scour around an offshore platform  

SciTech Connect

On the whole offshore scour has proved less of a problem than one might fear without being overly pessimistic, based on experience from other hydrotechnical works. The offshore setting, the environment as well as the structures, was simply beyond the reach to which conventional concepts and models could be safely extrapolated. The essentially empirical art of sediment engineering had to acquire a new empirical base. Today we know a lot more than we did a decade ago, however, our knowledge is still fragmentary, and we have no unifying theory yet.

Carstens, T.

1983-01-01

173

Maritime and offshore structure maintenance  

SciTech Connect

This volume provides the most up-to date material available on methods of keeping maritime installations operational. It also draws out the exceptionally valuable expertise that has been gained from servicing the major installations in the North Sea and elsewhere in the world. Subjects cover maintenance and repair including a detailed analysis of structural maintenance on specific structures. Papers include expertise in North Sea structures, corrosion protection of a North Sea platform, maintenance of ports overseas, East Africa, low maintenance concrete and maintenance of steel offshore structures. Guidelines are also included for the inspection and maintenance of marine facilities and offshore installations.

Not Available

1986-01-01

174

Offshore wind farm layout optimization  

NASA Astrophysics Data System (ADS)

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.

Elkinton, Christopher Neil

175

Offshore fares well in energy storm  

SciTech Connect

The effects of the worldwide economic slowdown on the energy industry in general, and offshore petroleum production activity, in particular is discussed. The world crude oil supply is reviewed, and the effects of the petroleum glut are evaluated for onshore and offshore activity. Offshore drilling has fared better than most of the other energy industry sectors, primarily because major operators, worldwide, still view the offshore as the prime province for large oil discoveries, particularly in the United States. (JMT)

Ball, E.R.

1982-05-01

176

Handling the pressure on an offshore rig.  

PubMed

The chief instigator of offshore stress is time which in oil parlance is money, writes Patrick Whyte, an offshore medical officer. He explains that medical personnel by showing that they practice a healthy lifestyle on the offshore oil rigs can set a practical example of coping with the stressful conditions. PMID:1775283

Whyte, P

1991-11-01

177

No slack for offshore workover industry  

Microsoft Academic Search

The lack of good drilling prospects offshore, the increasing value of current hydrocarbon production and the age of many OCS wells are all serving to make workover operations offshore a highly viable industry. Offshore operators are finding it cheaper to obtain added production through workovers than exploration. Virtually every producing well becomes deficient at some time in its life span

1978-01-01

178

Advanced transmission solutions for offshore wind farms  

Microsoft Academic Search

Future offshore wind farms will have large power ratings and will be situated much further offshore than current projects. The associated costs for grid connection will be high. This paper explores alternative methods of grid connection. By creating synergies with other applications for offshore power transmission, the total costs will be lower. Such synergies include the bundling of multiple wind

W. L. Kling; R. L. Hendriks; J. H. den Boon

2008-01-01

179

OFFSHORE ARCTIC PIPELINE OIL SPILL RISK ASSESSMENT  

Microsoft Academic Search

While offshore arctic pipelines have been under consideration for more than 25 years, few have been built. Renewed interest in offshore arctic oil and gas has necessitated the design of pipelines capable of both overcoming the technical challenges of the arctic offshore environment and minimizing the risk to it. This paper describes a quantitative risk assessment completed by BMT Fleet

A. Dinovitzer; R. Lazor; D. Hinnah

2004-01-01

180

Measuring safety climate on offshore installations  

Microsoft Academic Search

The human and organizational factors affecting safety were examined on 10 offshore installations using the Offshore Safety Questionnaire. The questionnaire contained scales measuring work pressure and work clarity, job communication, safety behaviour, risk perception, satisfaction with safety measures and safety attitudes. A total of 722 UK offshore workers (33% response rate) from a range of occupations completed and returned the

Kathryn Mearns; Rhona Flin; Rachale Gordon; Mark Fleming

1998-01-01

181

Use of stratigraphic and lithofacies maps in hydrogeologic studies: Examples from the General Separations Area, Savannah River Site, S. C  

Microsoft Academic Search

Stratigraphic and lithofacies maps are effective tools for assessing hydrologic properties of Tertiary aquifer and confining units in the 15mi[sup 2] General Separations Area (GSA) at the Savannah River Site, S.C. Pumping tests and laboratory permeability data indicate that the type, geometry, and spatial distribution of lithofacies are important factors controlling the lateral and vertical variability of hydraulic conductivity in

P. A. Thayer; A. D. Smits; M. K. Harris

1993-01-01

182

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

SciTech Connect

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.

Abreu, V.S. (Petrobras and Rice Univ., Houston, TX (United States))

1996-01-01

183

Technology for developing marginal offshore oilfields  

SciTech Connect

It has been estimated that approximately 800 marginal offshore oilfields exist worldwide. Therefore, marginal field technology will represent a major factor in the future of oil and gas developments. This review covers this very broad topic. The basic technology and its current applications are examined, future systems are assessed and operational and cost data from existing marginal field development schemes are presented. CONTENTS: Preface. Chapter 1: The Challenge of Marginal Fields. 1.1 What is a Marginal Field. 1.2 Offshore Oil Technology-An Historical Perspective. Chapter 2: Elements of a Marginal Field Development Scheme. 2.1 Production Supports. 2.2 Risers. 2.3 Subsea Equipment. 2.4 Storage. 2.5 Offshore Loading Systems. 2.6 Processing Facilities. Chapter 3: Existing Marginal Field Technology. 3.1 Introduction. 3.2 Jack-Up Systems. 3.3 Semi-Submersible Systems. 3.4 Monohull Based Systems. 3.5 Other Relevant Systems. Chapter 4: Current and Future Marginal Field Development Concepts. 4.1 Concepts Based on the Use of a Semi-Submersible. 4.2 Concepts Based on the Use of a Tanker Production Support. 4.3 Concepts Based on the Use of a Jack-up Production Support. 4.4 Concepts Based on Articulated Towers. 4.5 Concepts for Deepwater. 4.6 Extended Well Production Testing. Chapter 5: Construction and Operating History of North Sea Floating Production Systems. 5.1 The Argyll Experience. 5.2 The Buchan Experience. Chapter 6: Marginal Field Economics and Costs. 6.1 Cost Parameters: Their Relative Importance and Sensitivity. 6.2 Cost Elements for Marginal Field Production Systems. Bibliography. Appendix 1: Conversion Factors. Appendix 2: Glossary of Terms. Index.

Fee, D.A.; O'Dea, J.

1986-01-01

184

Offshore oil exploration and exploitation  

SciTech Connect

Exploration and drilling for petroleum in the North Sea is described. There are about 30 rigs drilling in the North Sea at present. Precautions, regulations and liability in such drilling are described. In the world at the end of 1978, there were about 400 rigs of various types drilling for oil offshore. (LTN)

Not Available

1980-03-01

185

Designing “quiet” into offshore projects  

Microsoft Academic Search

This paper provides some design guidance to assist in addressing and controlling underwater noise of an offshore project-be it oil rig, wind turbine, tidal power or other structure floating on the water or bottom mounted. The importance of a Plan to address and abate noise in order to achieve an underwater-radiated noise goal will be highlighted. The Plan's elements usually

R. W. Fischer

2010-01-01

186

Foundations for offshore wind turbines.  

PubMed

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

Byrne, B W; Houlsby, G T

2003-12-15

187

Geology of offshore central California  

Microsoft Academic Search

The offshore central California margin records Mesozoic and Cenozoic events attributable to continental and oceanic plate interactions. Terranes, some carried thousands of kilometers northward on the Kula and\\/or Farallon plates, were accreted to North America by late Eocene. Following accretion to North America, terranes along the margin were silvered and redistributed by strike-slip motion along the San Andreas and related

D. S. McCulloch; S. D. Lewis

1988-01-01

188

Offshore oil: Correctness of perspective  

Microsoft Academic Search

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

1993-01-01

189

Titanium for offshore oil drilling  

Microsoft Academic Search

By reducing maintenance and improving component efficiency, titanium and its alloys can compete in cost with the less expensive metals traditionally used for offshore drilling equipment. Navy research has demonstrated successful applications for heat exchangers, valves, pumps, and chlorination systems; excellent possibilities for the future include deepwater production equipment, risers, prestressed riser connectors, fixtures, and fittings. For the main platform

D. F. Hasson; C. R. Crowe

1982-01-01

190

Service bases for offshore oil  

Microsoft Academic Search

In January 1978, the U.S. Department of the Interior will sell leases allowing drilling for oil and gas in an area of the North Atlantic called Georges Bank, which is approximately 200 miles south east of Maine. The first onshore facilities established to support offshore drilling operations are Service Bases, which serve as the logistical link between onshore suppliers and

C. S. Colgan; J. Lindvall

1977-01-01

191

Integrated stratigraphic analysis of turbidite system reservoirs: East Breaks Block 160 field, offshore Texas Pliocene-Pleistocene  

SciTech Connect

Four Pliocene to Pleistocene reservoirs of the East Breaks Block 160 field are interpreted as deep-water sand deposits of turbidite origin: the oldest (Globoquadrina altispira) is about 50 mi downslope from its age-equivalent shelf; the youngest (Trimosina A) is only 6-10 mi downslope from its shelf. Electric-log correlations and facies analysis for both reservoirs suggest channel-fed deposition of aggradational lobes with basal sheet sands. Biofacies indicate deposition at middle to upper bathyal water depths (> 600 ft). Seismic facies analysis shows the reservoir interval correlates with discontinuous, variable-amplitude, non-parallel reflection character. This sand-prone seismic facies has a lobate map pattern within the isochron thicks of the Block 160 salt-withdrawal basin. A depositional model for this system includes (1) deposition during a sea level lowstand, (2) sediment supplies from a shelf-edge deltaic system, (3) transport by gravity flow process through physiographic lows on the slope, and (4) deposition as intraslope basin fans consisting of sheet, lobe, and channel deposits.

Armentrout, J.M.; Malecek, S.J.; Braithwaite, P.; Beeman, C.E.

1989-03-01

192

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

SciTech Connect

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.

Posamentier, H.W. (Esso Resources Canada Ltd., Calgary, Alberta (Canada)); James, D.H. (Esso Exploration and Production, Leatherhead (United Kingdom))

1991-03-01

193

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)

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.

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

194

Offshore Testing of Booms and Skimmers.  

National Technical Information Service (NTIS)

The Minerals Management Service and Conservation and Protection Agency, Environment Canada, initiated open ocean oil spill response equipment performance evaluations in 1984. The objective of this study was to develop a nonpolluting and cost-effective tes...

1987-01-01

195

Offshore Renewable Energy R&D (Fact Sheet)  

SciTech Connect

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.

Not Available

2011-10-01

196

Punctuated Stratigraphic Appearance of Cold-Water Coral Reefs  

NASA Astrophysics Data System (ADS)

Existing and new data acquired with an AUV document a high abundance of cold-water coral mounds in the bottom of the Straits of Florida (SoF). These mounds display a large variability of shapes and heights. The abundance and variability encountered in these and modern cold-water coral mounds elsewhere is in stark contrast to lack of reported ancient cold-water coral reefs. Furthermore, the stratigraphic distribution suggests that cold-water corals punctuate the stratigraphic record with times of bloom and times of near complete absence. In the Florida Bahamas region, for example, the stratigraphic distribution is non-uniform. Preliminary age dating of the modern coral mounds produce ages of a few hundred to 1300 years for corals at the surface of the mounds. Sub-bottom profiles and seismic data across the investigated mound fields reveal that the "modern" mounds root in Pleistocene strata but are absent in the Pliocene strata below. Cores taken during ODP Legs 101 and 166 in the SoF confirm the punctuated appearance as deep-water coral rubble was penetrated only in the Pleistocene and in the upper Oligocene strata. The vast occurrence of Oligocene cold-water coral mounds is also visible on a 2-D seismic line in the northern SoF and on a 3-D seismic survey in the southwestern portion of the SoF. In this latter data set a mid-Miocene and the base of Tertiary seismic horizon also image mounded features. These spikes in reef development indicate that environmental conditions were only occasionally favorable for reef growth. The punctuated appearance is surprising as the core and seismic data document continuous current activity since the late Miocene in the SoF. We speculate that the "modern" bloom of cold-water coral reefs in the Pleistocene coincides with the onset of the large barrier reef systems in the Australia and Belize.

Eberli, G. P.; Correa, T.; Massaferro, J. L.

2008-05-01

197

Documenting volcano-tectonic episodes in Mars' stratigraphic record  

NASA Technical Reports Server (NTRS)

Global geologic maps of Mars at 1:15,000,000 scales were digitized to obtain accurate measurements of the areal extent of 90 geologic units. These data were used to determine the resurfacing history of Mars by volcanic, eolian, fluvial, periglacial, and impact processes. This work is presently being extended to focus on the extent, magnitude, and duration of volcanism and tectonism (mainly faulting) throughout each of the three time-stratigraphic systems. This work involves detailed mapping to assess volcano-tectonic episodes in terms of their occurrence in eight epochs that represent subdivisions of Martian periods.

Scott, David H.; Tanaka, Kenneth L.

1987-01-01

198

Alaskan Peninsula Cenozoic stratigraphy: stratigraphic sequences and current research  

SciTech Connect

Geology of the Alaska Peninsula-Island Arc and Continental Margin, by C.A. Burk, is the principal reference for stratigraphic studies on the Alaska Peninsula. Burk mapped the Phanerozoic stratigraphy and provided a geologic history and structural interpretation of the area between Wide Bay and Unimak Island. Cenozoic rocks were mapped as three unconformity-bounded sequences. Recognition of specific formations was difficult due to similarity of lithofacies, isolated outcrops, rapid facies changes, and alteration and burial by young volcanics. Consequently, megafossil assemblages were relied upon to facilitate correlations between study areas. The three unconformity-bounded Cenozoic sequences are: (1) the Paleogene Beaver Bay Group consisting of three formations: the dominantly nonmarine Tolstoi Formation, the dominantly marine Stepovak Formation, and the volcanic Meshik Formation. Current work suggests these units are at least in part coeval facies of late Paleocene through Oligocene age. (2) The Neogene Bear Lake Formation consisting of the lower Unga Conglomerate Member and an unnamed upper member. Rapid facies changes and incorrect reports of fossil occurrence have resulted in confusion of stratigraphic relationships within this sequence of middle to late Miocene age. (3) A late Neogene informally defined upper sequence consisting of interbedded marginal marine, coastal-plain, and volcanic facies. Current work suggests this sequence is Pliocene through Pleistocene in age.

Allison, R.C.; Armentrout, J.M.

1985-04-01

199

Pipelaying in artic offshore waters  

SciTech Connect

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.

Langner, C. G.

1985-11-19

200

Offshore compressor station under way  

Microsoft Academic Search

Stingray Pipeline Co.'s offshore compressor station in West Cameron Block 509 of the Gulf of Mexico will, upon completion, process over 1 billion CF\\/day of natural gas. Six 3400-hp Solar Centaur recuperated-cycle gas turbine compressors will be used in the compressor facilties, which include a jacket, cellar deck, piping deck, and compressor deck. The 88 x 165 ft station, which

Ewing

1975-01-01

201

Offshore-plant economics bared  

Microsoft Academic Search

Pace Marine Engineering Systems, Inc.'s study of the economics of 200 specific types of offshore natural-gas processing plants takes no firm position either for or against plants built on marine platforms, concluding that the return on investment varies considerably with plant size, natural-gas price, water depth, product delivery distance, and other factors. Pace does note that LNG manufacture on an

Prescott

1976-01-01

202

Significance of Quaternary and Experimental Fluvial Systems to Interpretation of the Stratigraphic Record  

NASA Astrophysics Data System (ADS)

Studies of Quaternary and experimental fluvial systems provide significant insight for interpretation of fluvial deposits in the stratigraphic record, ranging from measurement of processes and relevant scales of key architectural elements, to process-based understanding of fluvial systems in sequence stratigraphic models. One key advantage for Quaternary and experimental systems is they commonly provide the ability to test, in a classical verification or falsification sense, interpretations, models and their alternatives that were developed from the stratigraphic record alone. First, scaling relationships developed from Quaternary fluvial deposits can be utilized to constrain interpretations of ancient strata, as well as predict the scale of channel fills, channel-belt sand bodies, and incised valleys. Scaling relationships are defined by power laws, with absolute dimensions that scale to drainage area, water flux, and sediment flux. Width-to-thickness ratios for channel fills range from 10-20:1, whereas channel-belt sand bodies upstream from backwater effects commonly range from 70-300:1, and 20-40:1within the backwater zone, where channel migration is limited. Quaternary incised valleys range from 25-150 m in thickness, and ~5-100 km in width, with width-to-thickness ratios of ~500-800. Scales of Quaternary channel fills and channel-belt sand bodies overlap are consistent with compilations from the ancient record. However, even the smallest Quaternary incised valleys reside in the uppermost part of the domain of published ancient valleys, with ancient examples overlapping significantly with modern channel fills and channel belts. We suggest that many ancient examples have been overinterpreted because of a lack of objective criteria for differentiating channel fills, channel belts, and incised valleys. Second, incised valleys have long played a key role in sequence-stratigraphic interpretations. For incised valleys in the stratigraphic record, either in outcrop or subsurface data, the sequence boundary is most commonly defined by the base of fluvial incision, which demarcates a significant basinward shift of facies, and is assumed to be an unconformity that everywhere separates younger strata above from older strata below. This classical interpretation is derived from a model for fluvial incision and sediment bypass during relative sea-level fall: fluvial deposits that rest on the sequence boundary are commonly assumed to represent filling of an empty container during late lowstand or early transgression. However, the model of fluvial incision and sediment bypass during relative sea-level fall has never been verified and does not stand up to scrutiny in Quaternary systems or experiments. Moreover, sediment bypass and deposition within incised valleys are not mutually exclusive: a large proportion of fluvial sediment is in transit over the duration of a base-level cycle, even though erosion and channel-belt deposition continuously redefines the valley shape, and at any one point the basal valley-fill surface is the same age as fluvial deposits that rest on top of it. Last, extension of valleys across a newly emergent shelf is accompanied by linked channel-belt deposition and delta progradation, such that the base of fluvial incision does not qualify as an unconformity or meet traditional criteria for a sequence boundary.

Blum, M. D.; Martin, J. M.

2012-12-01

203

OffshoreQA: A Framework for Helping Software Development Outsourcing Companies Comply with ISO 9001:2008  

Microsoft Academic Search

This paper proposes OffshoreQA, a framework for supporting the efforts of offshore software development outsourcing vendors to comply with ISO 9001:2008 and in particular clause 7, which relates to product realization. The solution consists of an integrated requirements management, configuration management and test management system that define the main roles during each software development phase for every site. Consequently, it

Hassan Annous; Lelia Livadas; Gail Miles

2010-01-01

204

Visual Stratigraphic Correlation and Anaglyph 3-D Visualizations Using GigaPan Imagery: Examples from Western Kansas  

NASA Astrophysics Data System (ADS)

GigaPan images of outcrop, quarry, and roadcut exposures have been captured and are being used to test the efficacy of a novel visual comparison technique in addressing issues of stratigraphic correlation of sub- units within the Upper Cretaceous Niobrara Formation in Rooks, Ellis, Gove, and Trego Counties in northwest Kansas. Through the use of side-by-side implementations of the web-based GigaPan Flash viewer, distinctive individual layers and stratigraphic sequences can be matched in a highly intuitive visual manner. Incorporating adequate quantitative measures of scale is a challenge that remains to be solved before high precision correlation can be done with GigaPan imagery, however semi-quantitative and qualitative preliminary results suggest that this device may become a powerful research tool. Application of the visual correlation technique to the teaching of stratigraphic correlation concepts in the classroom offers a novel and interactive way for students to experience the joy of discovery in a virtual field environment. A method for creating anaglyph GigaPan images with the current GigaPan robot will also be described; the resulting images represent another way to significantly enhance classroom-based virtual field experiences.

Schott, R. C.

2008-12-01

205

Offshore and arctic frontiers -structures, ocean mining  

SciTech Connect

The systematic development of offshore technology is discussed. Today, this technology enables the production of approximately 14 million barrels of oil per day, or 26% of oil production worldwide. The evolution in offshore structures is examined with emphasis on jacket and jackup platforms. Challenges are explored. Microprocessors, data-base management, and artificial intelligence are mentioned as having an impact on the offshore and arctic oil industry.

Chung, J.S.

1985-05-01

206

1991 worldwide offshore contractors and equipment directory  

SciTech Connect

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.

Not Available

1991-01-01

207

Geological history of the Flemish Pass Basin, offshore Newfoundland  

SciTech Connect

In this paper the authors present a seismic-stratigraphic interpretation of the Mesozoic and Tertiary geologic history of the Flemish Pass Basin, offshore Newfoundland, based on seismic data and data from seven wells that were integrated on the BP subsurface integrated interpretation system (SIIS). Four megasequences are identified. Megasequence 1 (MSI) is Triassic to lower Berriasian, and includes poorly known sediments associated with Triassic-Early Jurrasic rifting prior to spreading between the North African and American continents. The uppermost mappable unconformity-bounded unit within MSI contains major Kimmeridgian to Portlandian marine source rocks deposited in two east-west-trending subbasins in the Baccalieu and Gabriel areas. During the early Berrasian, pronounced rifting linked to the subsequent spreading of Iberia from the Grand Banks (Barremian-Aptian) led to regional deepening and deposition of clastic sediments (MS2) in two northeast-southwest-trending, fault-bounded subbasins in the Baccalieu and Gabriel areas. In the Aptian, Early Cretaceous subbasins were inverted due to strike-slip movement as extension assumed a northeast-southwest orientation prior to movement of Greenland/Europe away from Labrador (Albian). MS3 sediments fill northwest-southeast trending fault-bounded depocenters typically located on areas that had formed highs during Early Cretaceous. Postrift sedimentation continued from the Albian( ) to the present with Upper Cretaceous pelagic limestone and later clastic sediment deposition. 37 refs., 19 figs., 1 tab.

Foster, D.G.; Robinson, A.G. (BP Exploration Operating Company Ltd., Uxbridge (United Kingdom))

1993-04-01

208

78 FR 18614 - National Offshore Safety Advisory Committee  

Federal Register 2010, 2011, 2012, 2013

...and other matters affecting the oil and gas offshore industry. These meetings are...Areas on Foreign Flag Mobile Offshore Drilling Units (MODUs); (c) Safety...Register notices that affect the offshore industry; (4) USCG Outer...

2013-03-27

209

Stratigraphical distribution of the Ordovician conodont Erraticodon Dzik in Argentina  

NASA Astrophysics Data System (ADS)

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 Cóndor 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 Lindström, Oepikodus intermedius Serpagli, Baltoniodus triangularis (Lindström), Baltoniodus navis Lindström, Yangtzeplacognathus crassus (Chen and Zhang) and Eoplacognathus pseudoplanus (Viira) indicates they value for biostratigraphic correlation.

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

2013-08-01

210

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

SciTech Connect

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.

NONE

1995-12-31

211

Chemical Contaminants as Stratigraphic Markers for the Anthropocene  

NASA Astrophysics Data System (ADS)

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.

Kruge, M. A.

2012-12-01

212

Forward stratigraphic modeling of the Permian of the Delaware Basin  

SciTech Connect

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.

Qiucheng, Ye; Kerans, C.; Bowman, S. (Univ. of Texas, Austin, TX (United States)) (and others)

1996-01-01

213

Geologic mapping and stratigraphic investigations of the lunar crater Tycho  

NASA Astrophysics Data System (ADS)

We produced a new geologic map and studied important stratigraphic relationships for Tycho crater. This crater is ~102 km in diameter and is located in the southern highlands on the nearside of the Moon. We used high-resolution Lunar Reconnaissance Orbiter Camera (LROC) and Selenological and Engineering Explorer (SELENE) Terrain Camera (TC) images for detailed mapping, stratigraphic investigations, and dating of geologic units with crater size-frequency distribution (CFSD) measurements. In addition, we used Clementine FeO and TiO2 maps [1] and Moon Mineralogy Mapper (M3) [2] data to investigate the mineralogy. CSFD measurements at young lunar craters are important for helping us better understand the impact rate over the last billion years [3]. Melt pools dated with CSFDs on LROC Narrow Angle Camera (NAC) images, show model ages between 24.2 ± 5.6 Ma and 80.0 ± 14.7 Ma, whereas our model age for the ejecta blanket is 119 ± 12 Ma. The apparent absolute model ages measured for melt pools at Tycho are younger than the ejecta blanket. However, the impact melt and ejecta blanket should have formed at about the same time [4]. One interpretation of the discrepancies between the model ages of the melt pools and the ejecta blanket is that they have different target properties, i.e., the melt pools could be less porous and stronger [3,5]. Alternatively, self-secondary cratering might cause differences in CSFDs [6]. Our detailed geological map shows the distribution of melt pools in the study area. In particular, it shows a large coherent melt sheet within the crater, melt pools and flows along the terraced crater rim, and melt pools on the continuous ejecta blanket. The mapped distribution of melt pools is consistent with an oblique impact of the Tycho impactor from the southwest, as proposed by [7,8]. In addition to the distribution, we will also present results of the volume of melt pools associated with Tycho.

Krüger, T.; Hiesinger, H.; van der Bogert, C. H.

2012-04-01

214

Shallow stratigraphic controls on fluid and solute fluxes across the sediment-water interface of an estuary (Invited)  

NASA Astrophysics Data System (ADS)

Geologic heterogeneity influences the discharge of fresh groundwater to coastal waters and the circulation of saline surface water across the sediment-water interface. Here, we quantify the spatial distribution of shallow surface water-groundwater mixing, associated geochemistry, and submarine groundwater discharge (SGD) near a paleovalley feature in Indian River Bay, Delaware using a hand resistivity probe, seepage meters, and pore water samples. In the interfluve far from the paleovalley, fresh groundwater discharges rapidly near the coast. The discharging groundwater is relatively oxygenated, low in DOC, and high in nitrate. Short residence times in the shallow mixing zone provide little opportunity for geochemical transformation in discharging groundwater. In contrast, near the peat-covered paleovalley, fresh groundwater discharges farther offshore along the paleovalley margins at a moderate rate. Fresh groundwater near the paleovalley is relatively reducing, lower in nitrate, and higher in iron(II) and sulfide. Excess iron(II) in shallow pore water indicates iron reduction along shallow flow paths. In locations with little to no fresh groundwater discharge, the depth of saline surface water exchange is generally greater, and elevated sulfide, ammonium, and DOC in the shallow sediments likely indicate reduction of surface water-derived sulfate and microbial oxidation of organic matter. By modifying patterns of groundwater discharge and the nature of shallow mixing zones, paleovalleys and other stratigraphic features influence the geochemistry of fresh SGD and redox reactions near the sediment-water interface, affecting rates and patterns of geochemical fluxes to coastal surface waters.

Sawyer, A. H.; Lazareva, O.; Chan, C. S.; Crespo, K.; Stieglitz, T. C.; Michael, H. A.

2011-12-01

215

Offshore drilling and production structure  

SciTech Connect

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.

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

1982-02-09

216

Electrical interconnection for offshore wind energy systems  

Microsoft Academic Search

The interconnection and transmission arrangements proposed during the Phase I Department of Energy study of offshore wind power are summarized and this is extended to examine how a 2 GW array located 20-30 km offshore would be connected and operated. The extent to which provision for security against cable damage can be justified is considered together with the philosophy which

G. E. Gardner; P. J. Franklin

1985-01-01

217

Fibre-reinforced caissons for offshore applications  

Microsoft Academic Search

Steel caissons currently used on offshore platforms for the uplift of seawater onto platform topsides, for example, are susceptible to corrosion, and some operators have had to replace corroded caissons during service. The use of fibre reinforced plastics (FRP), in particular glass-fibre (GRP), has been explored by a number of offshore operators as an alternative to steel, principally due to

P. J. Boothby; C. D. Johnstone

1997-01-01

218

Offshore wind energy in the world context  

Microsoft Academic Search

The interest for the exploitation of the offshore wind energy is growing in Europe, where man land use is very high resulting in strong limitation to the installation of onshore wind farms. The today offshore operating wind power is 12 MW, with two wind farms in Denmark and one in Netherlands; it starts to be significant (0.6%) in terms of

Gaetano Gaudiosi

1996-01-01

219

Arctic Offshore Oil and Gas Technology.  

National Technical Information Service (NTIS)

This technical background briefing report is intended to assist in planning engineering research oriented toward Arctic offshore oil and gas recovery. The current five-year leasing schedule for the ice-prone waters of the Arctic offshore has been illustra...

W. M. Sackinger

1982-01-01

220

Judging defect severity on offshore pipelines  

Microsoft Academic Search

In spite of the great care taken in manufacturing, installing, and protecting offshore pipelines, defects often occur and a few have caused pipeline failures. Criteria and methods for assessing the severity of pipeline defects are well known, but their application to offshore lines calls for extra considerations. Defects can arise during pipe fabrication or pipelaying; they can also result from

J. F. Kiefner; W. A. Maxey

1982-01-01

221

Exploration potential of offshore northern California basins  

Microsoft Academic Search

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

S. B. Bachman; J. K. Crouch

1988-01-01

222

Arctic offshore drilling: a new challenge  

Microsoft Academic Search

The arctic offshore environment provides the drilling industry with its greatest challenge yet. Problems due to sea ice, high wind, extreme cold and poor bottom soil have required the design of special structures appropriate only for arctic offshore drilling. The challenge lies not just in the obvious factors of temperature and ice, but also the basic physics of ice problems

Wetmore

1985-01-01

223

Chinese Offshore Oil Production: Hopes and Reality  

Microsoft Academic Search

China started to develop its offshore oil resources in earnest in the early 1980s, when world oil price was high and projections about the potential of its offshore oil were extremely rosy. But as exploration and development efforts unfolded in the 1980s, disillusionment set in very quickly, given the mediocre amount of oil discoveries made. This article traces the development

Larry C. H. Chow; Wing-yin Lo

224

Offshore oil and gas technology assessment  

Microsoft Academic Search

In recent years offshore drilling and production technology has evolved in response to the challenges of deep waters and Arctic conditions. In this paper we discuss the development of offshore drilling rigs, platforms, subsea completion systems, pipelines, and tanker loading facilities. We conclude that current technologies modified to meet site-specific requirements are capable of drilling and producing oil and gas

L. Otteman; R. Crooke; R. Shoemaker

1985-01-01

225

Intraslope basin reservoirs deposited by gravity-driven processes: Ship Shoal and Ewing Banks areas, offshore Louisiana  

SciTech Connect

Seismic facies and high-resolution biostratigraphic analysis provide a sequence stratigraphic framework for interpreting lateral distribution of sand-prone facies and reservoir connectivity in the Ship Shoal 351-358 to Ewing Bank 988 area, offshore Louisiana. The interval of interest is an isochron thick interpreted as a lowstand systems tract deposited at bathyal water depths within an intraslope-basin. This basin is approximately 50 kilometers from the age equivalent shelf/slope break. The isochron thick was deposited between the late Pliocene Discoaster Pentaradiatus and early Pleistocene Discoaster brouweri Condensed Sections. The D. pentaradiatus-D. brouweri sequence consists of the synclinal fill of a salt withdrawal basin forming an isochron thick that thins onto adjacent salt-cored structural highs. This isochron interval was subdivided into four seismic facies and each was calibrated with local well data. Mapped patterns of these seismic facies suggest a network of channel systems within a slope valley supplying sand by gravity-driven processes into a local salt withdrawal intrastope-basin. Following the above analysis, three wells (351No.2, 359No.1, 988No.3) and two side-tracks (351No.2stNo.l and stNo.2) were drilled to further test the prospectivity of the area. Rock type and hydrocarbon predictions based on seismic facies analysis were confirmed by the wells. Sandstones occur within the axes of isochron thicks and shales dominate the isochron thins over paleo-highs with gradational facies between. Hydrocarbon accumulation occurs in two settings: (1) channel-fed lobes with blocky log character yield hydrocarbons within areas of structural closure; and (2) overbank facies which contain hydrocarbons in low resistivity pay both within and outside of structural closure. Local abundance peaks of planktonic microfossils provide correlation control between the four depositional lobes of this lowstand deposit.

Armentrout, J.M.; Malecek, S.J.; Mathur, V.R.; Neuder, G.L.; Ragan, G.M. [Mobile Oil Corp., Dallas, TX (United States)

1996-09-01

226

Intraslope basin reservoirs deposited by gravity-driven processes: Ship shoal and ewing banks areas, offshore Louisiana  

SciTech Connect

Seismic facies and high-resolution biostratigraphic analysis provide a sequence stratigraphic framework for interpreting lateral distribution of sand-prone facies and reservoir connectivity in the Ship Shoal 351-358 to Ewing Bank 988 area, offshore Louisiana. The interval of interest is an isochron thick interpreted as a lowstand systems tract deposited at bathyal water depths within an intraslope-basin. This basin is approximately 50 kilometers from the age equivalent shelf/slope break. The D. pentaradiatus-D. brouweri sequence consists of the synclinal fill of a salt withdrawal basin forming an isochron thick that thins onto adjacent salt-cored structural highs. This isochron interval was subdivided into four seismic facies and each is calibrated with local well data. The seismic facies are: Facies (1) hummocky-mounded facies with an internal reflection character of discontinuous variable amplitude, calibrated to thick, flat-based blocky to fining-upward sandstones interpreted as local sheets deposited as channel-fed depositional lobes; Facies (3) clinoform-wedge facies are characterized by continuous, uniform amplitude reflections and are calibrated with mudstones interpreted as part of a downslope prograding complex that downlaps and onlaps the hummocky- mounded facies; and Facies (4) parallel-continuous facies of relatively uniform amplitude correlated with mudstones that drape the other three facies throughout the study area and are interpreted as hemipelagic mudstone. Mapped patterns of these seismic facies suggest a network of channel systems within a slope valley supplying sand by gravity-driven processes into a local salt withdrawal intraslope-basin. Following the above analysis, three wells and two side-tracks were drilled to further test the prospectivity of the area. Rock type and hydrocarbon predictions based on seismic facies analysis were confirmed by the wells.

Armentrout, J.M.; Malecek, S.J.; Mathur, V.R. [Mobil Oil Corp., Dallas, TX (United States)] [and others

1995-06-01

227

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

NASA Astrophysics Data System (ADS)

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'.

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

2012-12-01

228

Stratigraphic architecture of the pyreneo-languedocian submarine fan, Gulf of Lions - western Mediterranean Sea  

NASA Astrophysics Data System (ADS)

In the Gulf of Lions, Western Mediterranean Sea, an enormous volume of siliciclasts was transferred into the deep basin during Quaternary glacio-eustatic fluctuations. One of the resulting sediment complex is the Pyreneo-languedocian sediment accumulation. Proposed deposition models for this sediment body are quite controversial. Some authors interpreted the feature as a sedimentary ridge, related to preferential deposition of turbidity currents over the right flank of the Sète submarine vanyon/valley that borders the Pyreneo-languedocian sediment body. In this study, on the contary, we favour a fan-like depositional model, being essentially controlled by the local Plio-Quaternary salt tectonics. Detailed mapping shows that the Pyrenean canyons located directly upslope the sedimentary accumulation is the major sediment feeder system, while salt-sediment interactions had direct implication for the fan depocenter generation and its sedimentary growth pattern. During the Pliocene, the area was subjected to a combined effect of overburden subsidence into the evacuated salt horizon and a significant distal salt thickening, due to a preferential basinward salt migration. This particular mode of salt migration had a major impact on the Quaternary sea-bottom morphology by creating a large midslope topographic low, providing space accommodation for clastics. Subsequent Quaternary sedimentation influx (the Pyreneo-languedocian complex) was then deposited in a slope salt-induced sub-basin. In this sense, the Pyreneo-languedocian fan is a unique feature at gulf scale, as depocenter location indicates that here unchannelized sedimentary environment occurs at slope level, thus in minor water depth in relation to all other deep-water sedimentary systems offshore Gulf of Lions. As well as that, a slope unchannelized deposition argues for proximal retention of sandy facies. Eventually, salt tectonics documented in the area is an interesting axample of salt-sediment interaction since the role of salt deformation is not directly identifiable from the surface morphology of the sedimentary complex. The external fan morphology does not reflect the degree of salt-tectonic intervention in the Pyreneo-languedocian stratigraphic organization.

Dos Reis, A. T.; Gorini, C.; Mauffret, A.; Mepen, M.

2003-04-01

229

Coupled Passive Margin Stratigraphic Evolution and Fluid Flow  

NASA Astrophysics Data System (ADS)

Continental margin processes are strongly influenced by patterns of overpressure and fluid flow within basin sediments. These patterns effect consolidation, slope stability, and the transport of heat and solutes. Numerous processes generate overpressure, but in many passive margins rapid deposition is thought to be a dominant mechanism, producing a two-way coupling between sedimentary processes and fluid flow. We study this coupling using a fully 2D margin-scale coupled stratigraphic evolution and fluid flow model. The sedimentary process model describes transport of sand and mud through coastal plain, shoreface, shelf, slope, fan, and rise depositional environments, as well as migration of internal boundaries between environments. The fluid flow model uses the finite element method (FEM) to solve for fluid flow on a dynamic grid. We explore the effects of 2D coupling for various basin geometries, sea-level histories, and sediment influx rates. We find that on a margin-scale, deposition tends to be localized in depocenters, which are initiated by sediment flux divergence across depositional environment boundaries (e.g. shoreline, shelf-break). Over timescales relevant to pore-pressure evolution, these boundaries and their associated clinoforms migrate in response to sedimentation and relative sea level change, resulting in complex dynamic patterns of overpressure. Although in some regions fluid flow is quasi-1D (vertical and forced only by local deposition), in many regions fluid flow is strongly 2D. Complex flow results from heterogeneous stratigraphy, with strong contrasts in sand and mud permeability determining preferential flow paths. On regional scales, confined horizontal sandy units, such as buried turbidite fan complexes, act as fluid flow conduits, inducing flow anisotropy. On smaller scales, interbedded sandy and muddy deposits produce anisotropic effective permeabilities with preferential horizontal flow. The complex dynamic geometries inherent to margin stratigraphic evolution have heretofore prevented effective margin-scale modeling coupled 2D stratigraphic-hydrologic system, but our computational approach introduces two innovations. A dynamic meshing technique allows for rapid meshing of arbitrary deposits while maintaining bounds on FEM conditioning and error. And a hierarchical mesh structure, which aggregates sediment layers into mesh nodes into finite elements, embeds sub-grid dynamics into the FEM model via layer averaged anisotropic permeabilities. Our results show that in regions of homogeneous lithology, quasi-1D numerical or asymptotic approximations are applicable, but that in regions with complex stratigraphy, strong anisotropy effects cannot be ignored. Our meshing and FEM approach is general and easily adapted for use with any sedimentary or backstripping model, and models including more grain sizes or processes have an even greater potential for complex 2D fluid flow. Hence our results demonstrate the viability and necessity of including 2D effects in continental margin fluid flow models.

Wolinsky, M. A.; Pratson, L. F.

2004-12-01

230

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

NASA Astrophysics Data System (ADS)

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

Swanson-Hysell, Nicholas L.

231

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)

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.

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

232

Pacific offshore record of plinian arc volcanism in Central America: 1. Along-arc correlations  

NASA Astrophysics Data System (ADS)

We collected 56 marine gravity cores from the Pacific seafloor offshore Central America which contain a total of 213 volcanic ash beds. Ash-layer correlations between cores and with their parental tephras on land use stratigraphic, lithologic, and compositional criteria. In particular, we make use of our newly built database of bulk-rock, mineral, and glass major and trace element compositions of plinian and similarly widespread tephras erupted since the Pleistocene along the Central American Volcanic Arc. We thus identify the distal ashes of 11 Nicaraguan, 8 El Salvadorian, 6 Guatemalan, and 1 Costa Rican eruptions. Relatively uniform pelagic sedimentation rates allow us to determine ages of 10 previously undated tephras by their relative position between ash layers of known age. Linking the marine and terrestrial records yields a tephrostratigraphic framework for the Central American volcanic arc from Costa Rica to Guatemala. This is a useful tool and prerequisite to understand the evolution of volcanism at a whole-arc scale.

Kutterolf, S.; Freundt, A.; PeréZ, W.; MöRz, T.; Schacht, U.; Wehrmann, H.; Schmincke, H.-U.

2008-02-01

233

Tephrochronology offshore Ischia Island, Tyrrhenian sea, Italy  

NASA Astrophysics Data System (ADS)

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 south

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

2010-05-01

234

Upper Paleozoic stratigraphic sequences in the Western Interior, USA  

SciTech Connect

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.

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

1993-04-01

235

Relative Age-dating -- Discovery of Important Stratigraphic Principles  

NSDL National Science Digital Library

When piecing together the geologic history of the Earth, geologists rely on several key relative age-dating principles that allow us to determine the relative ages of rocks and the timing of significant geologic events. In a typical Historical Geology class or textbook, instructors/authors briefly discuss the important early researchers in the geological sciences, and then give the name of the stratigraphic principle, useful for relative age-dating of rocks and events, that these 17th and 18th century scientists are credited with discovering. After the instructor/author defines these principles, students are usually shown several examples so they can see how the principle can be applied. But why not start with the examples and let students discover these principles for themselves? Students are split into small groups which each work to discover a different relative age-dating principle. The groups are shown photos and given handouts with drawings of rock outcrops illustrating the various principles. These handouts include worksheets for which they must answer a series of prompts that help lead them to the discovery of their relative age-dating principle. Groups must also invent a name for their principle, and select a spokesperson who will present the group's results to the rest of the class.

Steinberg, Roger

236

Stratigraphic traps in Silurian lockport dolomite of Kentucky  

SciTech Connect

The Lockport Dolomite has yielded commercial quantities of petroleum for nearly 100 years and continues to be an exploration target in eastern Kentucky. Reservoirs are largely confined to porous buildups and to erosional truncation along the Cincinnati arch. These stratigraphic traps developed under the influence of (1) sea level fluctuations, which controlled the development of reefal, skeletal-bank, and ooid-shoal facies across the carbonate shelf, (2) relict topographic highs in the underlying Keefer Sandstone and in the lower Lockport, which provided optimum sites for deposition of boundstones and grainstones, and (3) syndepositional movement of fault blocks, which localized skeletal buildups. Isopach thicks along the western edge of the study area represent erosional remnants beneath the Middle to Upper Devonian unconformity, rather than carbonate buildups. Porosity originated during subaerial weathering in the Devonian, and reservoirs were capped by the impermeable organic-rich Ohio Shale. Away from the unconformity, patch reefs and skeletal banks can be identified by thicks on isopach maps, by their clean gamma-ray signature, and by a relatively high log porosity. The distribution of buildups generally parallels earlier topographic highs or basement faults. Secondary porosity (intercrystalline dolomite and moldic vuggy) formed in the eogenetic zone during lowered sea level, and impermeable lagoonal and tidal-flat carbonates serve as seals. Because of the stacking of porous Lockport units, eastern Kentucky has good potential for multiple pay zones. 14 figures.

Smosna, R.; Conrad, J.M.; Maxwell, T.

1989-07-01

237

Stratigraphic placement and age of modern humans from Kibish, Ethiopia.  

PubMed

In 1967 the Kibish Formation in southern Ethiopia yielded hominid cranial remains identified as early anatomically modern humans, assigned to Homo sapiens. However, the provenance and age of the fossils have been much debated. Here we confirm that the Omo I and Omo II hominid fossils are from similar stratigraphic levels in Member I of the Kibish Formation, despite the view that Omo I is more modern in appearance than Omo II. 40Ar/39Ar ages on feldspar crystals from pumice clasts within a tuff in Member I below the hominid levels place an older limit of 198 +/- 14 kyr (weighted mean age 196 +/- 2 kyr) on the hominids. A younger age limit of 104 +/- 7 kyr is provided by feldspars from pumice clasts in a Member III tuff. Geological evidence indicates rapid deposition of each member of the Kibish Formation. Isotopic ages on the Kibish Formation correspond to ages of Mediterranean sapropels, which reflect increased flow of the Nile River, and necessarily increased flow of the Omo River. Thus the 40Ar/39Ar age measurements, together with the sapropel correlations, indicate that the hominid fossils have an age close to the older limit. Our preferred estimate of the age of the Kibish hominids is 195 +/- 5 kyr, making them the earliest well-dated anatomically modern humans yet described. PMID:15716951

McDougall, Ian; Brown, Francis H; Fleagle, John G

2005-02-17

238

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

SciTech Connect

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.

Cutler, A.H.; Flessa, K.W. (Univ. of Arizona, Tucson (USA))

1990-06-01

239

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

SciTech Connect

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.

Coughlin, R.M.; Bement, W.O.; Maloney, W.V. (Pecten International Company, Houston, TX (United States))

1993-09-01

240

Requirements for different components in cables for offshore application  

Microsoft Academic Search

The installation of offshore wind-farms and the increase in electricity trading between countries has resulted in an increased number of offshore submarine cable installations as an efficient way to solve many electricity supply issues. Although offshore cables with XLPE insulation are similar to land based cables, the offshore environment adds to the challenges of very long lengths, much more onerous

D. Wald; H. Orton; R. Svoma

2009-01-01

241

Risk analysis for offshore structures and equipment  

SciTech Connect

This work describes in detail the results of research on behalf of the EEC commission by an interdisciplinary team on a new technological and methodological approach to risk assessment for the stringent safety standards required in the offshore oil and gas industries. The text describes the methods adopted by other high-risk industries, such as nuclear and aerospace, and develops an adaption of the techniques for offshore structures and equipment. The system is applied to drilling facilities, production and processing, offshore loading, inspection, maintenance and repair.

Not Available

1987-01-01

242

Judging defect severity on offshore pipelines  

SciTech Connect

In spite of the great care taken in manufacturing, installing, and protecting offshore pipelines, defects often occur and a few have caused pipeline failures. Criteria and methods for assessing the severity of pipeline defects are well known, but their application to offshore lines calls for extra considerations. Defects can arise during pipe fabrication or pipelaying; they can also result from mechanical damage, internal and external corrosion, and mud slides. An offshore operator will rarely need to apply a criterion for determining whether to repair or remove a defect; however, when such a criterion would be useful, it should be modified to take advantage of the external pressure provided by the seawater.

Kiefner, J.F.; Maxey, W.A.

1982-05-24

243

Current and future offshore activities in Canada  

SciTech Connect

The development of innovative exploratory drilling systems for Canada's harsh Arctic offshore areas over the past decade and future activity in these areas, including possible production concepts, are discussed. The results can be applied in other Arctic areas of the world, including offshore Alaska. This operating experience will advance technology and serve as a basis for the design of Arctic offshore production and transportation systems. Unique technology has been developed and successfully used in the discovery of major accumulations of hyrodcarbons. Continued technological advances are anticipated to have widespread Arctic applications in both exploratory and production operations.

Hnatiuk, J.

1987-06-01

244

Offshore maintenance reduces cost and downtime  

SciTech Connect

Maintenance is the single activity offshore that can have the most impact on productivity, safety, and downtime. Unfortunately, unless it is well organized, maintenance may be carried out according to unchanging and often unnecessary routines. Overly rigid maintenance procedures, that are viewed by crews as ''makework'' assignments, are not conducive to quality or to failure-proof operation of key rig systems. An alternate system of maintenance, which Keydril has adopted on all its rigs, is designed to circumvent the problems of crew attitude and at the same time provide an effective preventive program that simply and efficiently manages all of the rig's operational requirements. The program consists of detailed maintenance and test procedures which are based on frequency analyses of the operating profiles of each piece of machinery. Keydril calls the program an Engineered Approach to Maintenance. The heart of the engineered approach system is a color-coded visual display of maintenance requirement cards (T-cards). These cards assign and describe specific tasks according to an analysis of the operating history of the unit itself and analyses of similar equipment on other company rigs. The second part of the engineered system is the use of high-technology testing methods that can remotely analyze various operating parameters and give early warning of equipment wear prior to failure. The equipment on board Keydril's rigs must be used, and rig personnel have to know that it will always work at satisfactory performance levels. The engineered approach to maintenance provides that assurance.

Danahy, J.W.

1983-08-01

245

Applying high-resolution sequence stratigraphic tools to the Texas continental margin to fine-tune conventional sequence stratigraphic models and improve reservoir prediction  

SciTech Connect

A regional sequence stratigraphic study of the Texas continental margin resulted in an improved understanding of Pleistocene-Holocene eustatic sea level fluctuations and their influence on depositional environments associated with several distinct systems: the Colorado/Brazos system, the Texas interfluve region, and the Rio Grande system. The dataset consists of approximately 7500 kilometers of high-resolution seismic profiloes, 200 borehole descriptions, and 12 sediment cores. The study involved analysis of three independent variables to better constrain Pleistocene-Holocene sea level history: coastal onlap derived from high-resolution seismic profiles; oxygen isotope data determined from selected sediment cores; and paleoenvironmental data developed from high-resolution micropaleontologic analyses. Combined lithologic data and seismic facies analysis is used to map the distribution of major depositional systems on the shelf during one complete glacial eustatic cycle. Our study provided anopportunity to fine tune conventional stratigraphic models with regard to the distribution of potential reservoirs relative to regionally mappable stratigraphic surfaces.

Anderson, J.A.; Banfield, L.A.; Eckles, B.J. (Rice Univ., Houston, TX (United States)) (and others)

1996-01-01

246

A Proposed Time-Stratigraphic System for Protoplanet Vesta  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

247

Stratigraphic traps for petroleum in wind-laid rocks  

SciTech Connect

Three major kinds of stratigraphic traps for petroleum exist in wind-deposited rocks: geomorphic, diagenetic, and system-boundary traps. Geomorphic petroleum traps are those in which oil is trapped in association with preserved topographic relief on eolian sands. The preserved relief may be inherited from the original dune field, modified by reworking, or created by erosion of dune sandstones prior to burial by the next layer of sediments. Diagenetic traps for petroleum are those in which oil is trapped by lateral changes in porosity and permeability within the wind-laid rocks. Usually, oil is trapped against cemented zones, which may be selective or nonselective of depositional facies. The propensity of eolian deposits to have diagenetic traps may be due to early cementation, reflecting the common association of desert dunes and evaporites. Traps for petroleum may also be created by decementation - typically the dissolution of early halite, gypsum, or anhydrite. System-boundary traps for petroleum are those in which oil is trapped at the updip depositional edge of the eolian-system deposits, where they intertongue with impermeable sediments of a different depositional environment. System-boundary traps can be sharp or diffuse. Sharp system-boundary traps can create or help create large single pools, such as the 1.6 billion bbl pool at Rangely oil field, Colorado. Diffuse system-boundary traps may contain as much oil as sharp system-boundary traps, but the oil is spread over a much wider area in a multitude of smaller pools, as in the Minnelusa Formation of northeast Wyoming. 17 figures.

Fryberger, S.G.

1986-12-01

248

Offshore turnkey drilling provides new opportunities  

SciTech Connect

Is offshore turnkey drilling a viable alternative to day rate contracts. With the recent success of several offshore turnkey wells, this contractual approach may provide some unique opportunities for the industry. But the decisions required to take on such an endeavor are not easy to make, particularly when the advantages and disadvantages for offshore turnkey drilling are compared to land turnkey drilling. With only 30 of some 27,000 offshore wells drilled under turnkey contracts, the move toward turnkey drilling hasn't been overwhelming, but more contractors and operators are looking at this approach. Basically, a turnkey contract calls for drilling a loggable hole to a predetermined depth for a fixed amount of money. Should the contractor fail to deliver a usable hole, for whatever reason, he is obligated under his contract to slide his rig over and drill another hole, at no additional cost to the client.

Moore, S.D.

1984-11-15

249

Offshore oil in the Alaskan Arctic  

NASA Technical Reports Server (NTRS)

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.

Weeks, W. F.; Weller, G.

1984-01-01

250

Proceedings of offshore and arctic operations, 1992  

SciTech Connect

This book contains the proceeding of the offshore and Arctic operations. Topics included are: Pile driving; Flexible pipes; QA/QC Requirements; Oil and gas exploitations and Off shore well-log analysis.

Tawfik, A.S. (Brown and Root Inc. (US)); Attia, F.G. (University of Houston (US))

1992-01-01

251

Civil engineering in the Arctic offshore  

SciTech Connect

This book presents the current state of practice and theory in the civil engineering aspects of offshore development in the Arctic. It also covers the emerging concepts and requirements, research and development needs, and a critique of present undergraduate programmes.

Bennett, F.L.; Machemehl, J.L.

1985-01-01

252

Evaluation of Sand Resources, Atlantic Offshore, Delaware.  

National Technical Information Service (NTIS)

Lithologic logs from 268 vibracores taken from the Delaware Atlantic offshore were evaluated for sediment type and compatibility with historical beach sediment textures. A model of sand resource evaluation, known as stack-unit mapping (Kempton, 1981) was ...

K. K. McKenna K. W. Ramsey

2002-01-01

253

Expanders do payouts offshore North Sea  

SciTech Connect

Rich associated gas may be beneficially processed offshore, to yield high value condensate to be spiked into the crude, whilst still producing gas with an acceptable nett calorific value. Actual turbo expander operating experience on the Occidental Piper North Sea Platform has demonstrated that expanders are reliable offshore. This paper, describes both the process and mechanical aspects that affect the choice of an expander system for an offshore application. For a given typical rich associated gas, three process options are compared, Joule-Thompson expansion, external refrigeration and a turbo expander system. The process study illustrates that a turbo expander system is comparable for the offshore situation with the other two options. The paper also describes the mechanical features that should be incorporated into the specification of an expander for use on a platform topsides.

Barnwell, J.; Wong, W.

1984-02-01

254

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

USGS Publications Warehouse

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.

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

2009-01-01

255

Arctic offshore drilling: a new challenge  

SciTech Connect

The arctic offshore environment provides the drilling industry with its greatest challenge yet. Problems due to sea ice, high wind, extreme cold and poor bottom soil have required the design of special structures appropriate only for arctic offshore drilling. The challenge lies not just in the obvious factors of temperature and ice, but also the basic physics of ice problems are not well understood. The arctic environment and the petroleum industry are discussed.

Wetmore, S.B.

1985-11-01

256

Grid Integration of Offshore Wind Farms  

Microsoft Academic Search

\\u000a Offshore wind farms tend to become bigger and far from the onshore point of connection. The developers and the system operators\\u000a are facing a number of technical, economical, and environmental challenges in transmitting the bulk power developed at these\\u000a offshore wind farms over long distances. In this Chapter, some of these issues are discussed, giving emphasis to the basic\\u000a system

Lie Xu

257

The impact of offshoring on firm competitiveness  

Microsoft Academic Search

Offshoring strategies, in spite of their continuous growth, have not always delivered the expected results: cost savings are\\u000a often much lower than expected, customers may be considerably upset, and relevant competences can be lost for the future.\\u000a This article looks at the impacts of offshoring on firm competitiveness, in the short and in the long term. The analysis is\\u000a based

Corrado Cerruti

2008-01-01

258

Decommissioning of Offshore Oil and Gas Installations  

Microsoft Academic Search

The offshore oil and gas industry had its beginnings in the Gulf of Mexico in 1947. The first offshore development used a\\u000a multipiled steel jacket to support the topside production facilities, a design which has since been used extensively. Now\\u000a there are more than 7000 drilling and production platforms located on the Continental Shelves of 53 countries [1]. Some of

M. D. Day

259

Corrosion control survey methods for offshore pipelines  

SciTech Connect

Construction, operation, and maintenance of offshore pipelines and other facilities are expensive. The consequences of an offshore corrosion failure can be devastating. For these reasons, cathodic protection (CP) has become a universally applied technique for mitigating corrosion. Marine pipelines are typically provided with CP by bracelet anodes of zinc or aluminum. Impressed current systems at platforms or onshore are also used as well as hybrid systems that use a combination of the two. In this paper survey techniques are described and evaluated.

Weldon, C.P.; Kroon, D. (Corrpro Co. Inc., North, Spring, TX (US))

1992-02-01

260

Stratigraphic evidence for an early Holocene earthquake in Aceh, Indonesia  

NASA Astrophysics Data System (ADS)

The Holocene stratigraphy of the coastal plain of the Aceh Province of Sumatra contains 6 m of sediment with three regionally consistent buried soils above pre-Quaternary bedrock or pre-Holocene unconsolidated sediment. Litho-, bio-, and chronostratigraphic analyses of the lower buried soil reveals a rapid change in relative sea-level caused by coseismic subsidence during an early Holocene megathrust earthquake. Evidence for paleoseismic subsidence is preserved as a buried mangrove soil, dominated by a pollen assemblage of Rhizophora and/or Bruguiera/Ceriops taxa. The soil is abruptly overlain by a thin tsunami sand. The sand contains mixed pollen and abraded foraminiferal assemblages of both offshore and onshore environments. The tsunami sand grades upward into mud that contains both well-preserved foraminifera of intertidal origin and individuals of the gastropod Cerithidea cingulata. Radiocarbon ages from the pre- and post-seismic sedimentary sequences constrain the paleoearthquake to 6500-7000 cal. yrs. BP. We use micro-and macrofossil data to determine the local paleoenvironment before and after the earthquake. We estimate coseismic subsidence to be 0.45 ± 0.30 m, which is comparable to the 0.6 m of subsidence observed during the 2004 Aceh-Andaman earthquake on Aceh's west coast.

Grand Pre, Candace A.; Horton, Benjamin P.; Kelsey, Harvey M.; Rubin, Charles M.; Hawkes, Andrea D.; Daryono, Mudrik R.; Rosenberg, Gary; Culver, Stephen J.

2012-10-01

261

3-D Stratigraphic Models of a Composite Barrier System, Northern New Zealand  

Microsoft Academic Search

DOUGHERTY, A.J. AND NICHOL, S.L., 2007. 3-D Stratigraphic models of a composite barrier system, northern New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 922 - 926. Gold Coast, Australia, ISSN 0749-0208 This paper presents for the first time, detailed three-dimensional stratigraphic models of both the Holocene and Pleistocene components of a double barrier

A. J. Dougherty; S. L. Nichol

262

A simple application of stereographic projection in the measurement of stratigraphic thickness  

NASA Astrophysics Data System (ADS)

A simple method for calculating the true stratigraphic thickness of beds measured indirectly using tape and compass along sloping transects oblique to the bedding strike is described. This method minimizes the need for complex trigonometric formulae that otherwise need to be adapted to different arrangements of bedding dip direction and traverse slope direction. The method is equally useful in calculating the true thickness of stratigraphic units penetrated in boreholes, and data collected from road cuttings oblique to the strike of beds.

Fowler, Abdel-Rahman; Hashem, Waheed

2013-09-01

263

Seismic definition of Lower Cretaceous delta, south Whale subbasin, offshore Newfoundland  

SciTech Connect

Recognition of stratigraphic traps in areas where previous prospects were structural is a trend attributable partly to the availability of new, high-quality seismic data. In the South Whale subbasin, offshore Newfoundland, Canada, such a change in exploration philosophy is presently being evaluated. Exploratory drilling offshore eastern Canada began in 1966 in the South Whale subbasin. By the end of 1973, 13 wells were drilled in this subbasin; however, lack of success discouraged further drilling. These wells evaluated large, salt-related structures, well defined by seismic data. Although an adequate reservoir was encountered in a number of these wells, faulting associated with halokinesis may have resulted in petroleum migration out of the reservoir. Interpretation of recently acquired high-quality seismic data indicate a delta in the Lower Cretaceous Missisauga Formation in the study area. Seismic dip sections across the delta show a shingled progradation pattern suggesting a wave-dominated depositional environment. The delta comprises approximately 400 km/sup 2/, with closure in the eastern half. Data from wells in the area indicate that adequate source and sealing beds could be present. Furthermore, rocks of similar age in the nearby Avalon basin contain significant petroleum accumulations, the most notable being within the Hibernia oil field.

Jayasinghe, N.R.; Stokes, R.E.

1986-05-01

264

Variability within upper offshore facies  

SciTech Connect

Large, undisturbed cores were collected adjacent to five of the barrier islands within the southeastern Atlantic Bight. Sampling was restricted to the narrow band of contemporary sedimentation within 16 km of the beach. X-radiography analyses of sediment texture, sedimentary structures, and bioturbation reveal significant variability within the upper offshore facies of a low-energy mesotidal nearshore environment. Samples collected off southern Hilton Head and off southern Wassaw consist of bioturbated muddy fine-grained sand. The relative predominance of silt- and clay-size detritus within the cores taken north of the Savannah River inlet reflect the high quantities of suspended organic and particular sediment flushing out the inlet mouth. Cores taken south of the Savannah River inlet off southern Tybee consist of clean, medium to coarse-grained sand which is replaced by bioturbate silty fine-grained sand farther south along a transect normal to Williamson Island. Tybee Island has undergone continuous erosion during the 20th century. Samples taken from the nearshore in this area may reflect a deficit in the sediment budget or may reflect that increased tidal currents around Tybee Inlet prevent the deposition of fines. Interpretation of these cores is complicated by suspected contamination. Less than 2 km from our sampling stations is a dumping site for material dredged from the Savannah River navigational channel. Two transects each were collected in the nearshore normal to Ossabaw and St. Catherines Islands. X-radiographs of these cores depict an interplay between bioturbate texture and physical sedimentary structures.

Paulsen, M.

1986-05-01

265

Reducing Offshore Transmission Requirements by Combining Offshore Wind and Wave Farms  

Microsoft Academic Search

The advantages of combining offshore wind and wave energy into a single farm include reduced hours of zero power output and reduced interhour variability. Both advantages facil- itate grid integration of variable renewables. The power output profile of a combined farm with wind and wave is substantially dif- ferent from a 100% offshore wind energy farm or a 100% wave

Eric D. Stoutenburg; Mark Z. Jacobson

2011-01-01

266

Offshore remobilization processes and deposits in low-energy temperate-water carbonate-ramp systems: Examples from the Neogene basins of the Betic Cordillera (SE Spain)  

NASA Astrophysics Data System (ADS)

General facies models developed for modern and ancient Mediterranean temperate-water carbonates in the last two decades have shown that the style of deposition on outer-ramp, slope, and basin environments in low-energy areas such as the Mediterranean Sea differs overall from that of high-energy open-ocean areas, given the wider variety of smaller-scale topographic and hydrodynamic conditions in the former setting. However, these depositional models generally lack relevant information about sedimentary processes, transport mechanisms and controlling factors on offshore sediment redeposition, which are potential sources of information for sequence stratigraphic, palaeoclimate and exploration studies. Several examples from the Neogene Betic basins of the western Mediterranean region have been selected to integrate the processes and controlling factors on the offshore sediment transport and the resulting deposits. Additional published data from other Mediterranean localities have also been considered.

Puga-Bernabéu, Ángel; Martín, José M.; Braga, Juan C.; Aguirre, Julio

2014-05-01

267

Sanaga Sud field - Offshore Cameroon, west Africa  

SciTech Connect

The Sanaga Sud field, offshore Cameroon, is located just northwest of the coastal town of Kribi in the northern part of the Douala basin. The discovery well, Sanaga Sud A-1, was drilled in 1979 to test an apparent horst block that contained a prominent horizontal seismic amplitude. The Douala basin is one of a series of passive margin basins located along the coastline of central and southern Africa, and formed during the rifting of Africa and South America during the Early Cretaceous. Drilling results showed that the amplitude was a gas/water contact. Two appraisal wells, SSA-2 and SSA-3, were drilled in 1981. All three wells tested gas and condensate. Total recoverable hydrocarbons for the field are estimated to be approximately 1 tcf of gas. The trap in this field is composed of tilted and rotated fault blocks composed of interbedded Aptian to Albian sandstones, siltstones, and shales. The fault blocks were truncated by erosion (breakup unconformity) and later buried by a considerable thickness of onlapping Upper Cretaceous and Tertiary shale. The late Albian erosional unconformity forms the top of the trap over most of the field. Geochemical studies indicate a Lower Cretaceous source for the hydrocarbons. The gross pay thickness averages 250 m with an average porosity of 23% and an average permeability of 142 md. Reservoir lithologies range from well-sorted, massive sandstones to poorly sorted fine sandstones and siltstones containing shaly laminations that are carbonaceous and micaceous. The field is located predominantly in Block PH-38, but part of the field is in the Londji concession. Mobil Producing Cameroon, Inc., is the operator of PH-38 and Total Exploration and Production Cameroon is the operator of the Londji concession.

Pauken, R.J. (Mobil New Exploration Ventures Co., Dallas, TX (USA))

1990-09-01

268

Polyamine sensitization in offshore workers handling drilling muds.  

PubMed

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

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

1989-11-01

269

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

NASA Astrophysics Data System (ADS)

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.

Pratt, Brian

2014-05-01

270

10 CFR 150.7 - Persons in offshore waters not exempt.  

Code of Federal Regulations, 2012 CFR

...2014-01-01 false Persons in offshore waters not exempt. 150.7 Section 150...IN AGREEMENT STATES AND IN OFFSHORE WATERS UNDER SECTION 274 Continued Commission Regulatory Authority in Offshore Waters § 150.7 Persons in offshore...

2014-01-01

271

Proceedings of the 25th annual offshore technology conference. Volume 3 - Construction and installation/field drilling and development systems  

SciTech Connect

This conference represents one of four volumes on offshore operation of oil, gas, and other mineral resource projects. This particular volume deals with the installation and design of offshore production platforms, marine risers, underwater pipelines, and oil/gas wellheads. It discusses the operations of the various systems, gives comparative evaluations of systems, provides the results of various materials testing programs, provides various engineered safety systems, and designs for various forms of anchoring systems for floating platforms.

Not Available

1993-01-01

272

Offshore oil gas trends in ROVs tooling  

SciTech Connect

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.

Jacobson, J.R. (Perry Tritech Inc., Jupiter, FL (United States))

1994-04-01

273

Stratigraphic and structural characteristics of the Romanian Black Sea shelf  

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

274

Fire-resistant pump protects offshore platform  

SciTech Connect

This paper reports on strict safety regulations for North Sea platforms which required the development of a disaster-resistant enclosure for a diesel-driven fire pump. Offshore oil and gas platforms have an excellent safety record for facilities that handle large volumes of volatile hydrocarbons. One major reason for this record is the attention paid to safety at these facilities where a small fire can quickly turn into a major disaster. In a recent project, Noise Control Technology Corp., Dallas, Texas, designed, manufactured and supplied an A60-rated fire pump enclosure for a North Sea platform. The A60 rating of enclosures or rooms is primarily an offshore standard of the International Maritime Organization and intended as a safety mandate for ships, offshore rigs, platforms and other marine installations.

Not Available

1992-10-01

275

Current and future offshore activities in Canada  

SciTech Connect

The development of innovative exploratory drilling systems for Canada's harsh Arctic offshore areas over the past decade is described. Future activity in these areas, including possible production concepts, is also discussed. The results of the experience in Canadian waters can be applied in other Arctic areas of the world including offshore Alaska. This operating experience will serve to further advance the drilling technology and will serve as a basis for the design of Arctic offshore production and transportation systems. Artificial islands, first commenced in 1972, are still being constructed but with improved designs and equipment. A step forward has been the use of subsea berms on which concrete or steel segmented caissons have been placed. Integrated-type steel caissons have also been adapted for placement on subsea berms, one of which is half of a crude oil tanker and a second, a purpose-built steel caisson to be placed this summer.

Hnatiuk, J.

1984-05-01

276

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

SciTech Connect

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.

Not Available

2012-02-01

277

46 CFR 131.320 - Safety orientation for offshore workers.  

Code of Federal Regulations, 2013 CFR

... false Safety orientation for offshore workers. 131.320 Section 131.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND...VESSELS OPERATIONS Preparations for Emergencies § 131.320 Safety orientation for offshore...

2013-10-01

278

Flexible liner safeguards environment during offshore workover  

SciTech Connect

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.

Not Available

1991-06-10

279

The Stability of Offshore Outsourcing Relationships  

Microsoft Academic Search

• \\u000a \\u000a \\u000a Offshore outsourcing of administrative and technical services has become a mainstream business practice. Increasing commoditization\\u000a of business services and growing client experience with outsourcing have created a range of competitive service delivery options\\u000a for client firms.\\u000a \\u000a \\u000a \\u000a \\u000a • \\u000a \\u000a \\u000a Yet, data from the Offshoring Research Network (ORN) suggests that, despite increasing market options and growing client expectations\\u000a related to service quality

Stephan Manning; Arie Y. Lewin; Marc Schuerch

2011-01-01

280

Exotic invertebrate species on offshore oil platforms  

Microsoft Academic Search

ABSTRACT: We report the presence,of 3 exotic invertebrate,species,inhabiting,offshore,oil and gas platforms on the Pacific offshore continental shelf (POeS) of central and southern California, USA. These exotic species,occur in high cover or density and may,negatively,affect populations,of native species on the platforms. Conspicuous,exotic species,(the bryozoan,Watersipora ?subtorquata and the anemone,Diadumene,sp.) were detected on 2 of 7 platforms,surveyed. An inconspicuous,exotic spe­ cies (the amphipod,Caprella

Henry M. Page; J Enifer E. Dugan; Carolynn S. Culver; JC Hoesterey

2006-01-01

281

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

NASA Astrophysics Data System (ADS)

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.

Hu, J.; Lokier, S. W.

2012-04-01

282

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

SciTech Connect

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.

Waters, A.C.; Carroll, P.R. (eds.)

1981-11-01

283

Organic geochemistry of sediments on the flanks of Tanner and Cortes banks offshore from southern California  

USGS Publications Warehouse

Holocene sediment, composed mainly of foram tests, occurs on the flanks of the Tanner and Cortes Banks, offshore southern California. The organic matter in this sediment differs in content and composition from the organic matter in nearby basins. Two sources of hydrocarbons are indicated: terrestrial plants and biodegraded or immature petroleum.

Rapp, J. B.; Kvenvolden, K. A.

1982-01-01

284

Control of multi-terminal VSC-HVDC transmission system for offshore wind power generation  

Microsoft Academic Search

A multi-terminal voltage source converter based high voltage DC transmission systems (MTDC) was used for grid-connection of large offshore wind power generation. The design of a control system was discussed. A four-terminal system was built to test the control idea. Simulation using PSCAD\\/EMTDC has been carried out under various load and fault conditions.

Shu Zhou; Jun Liang; J. B. Ekanayake; N. Jenkins

2009-01-01

285

Geochemical Characterization of Offshore Western Niger Delta Source Rock  

Microsoft Academic Search

A geochemical characterization of rock samples obtained from three offshore fields, MJ, MF, and ML, was carried out. Offshore oil and onshore oil samples were also studied for correlation. The gas chromatographic data showed that the three offshore fields studied exhibited different and unique geochemical signatures. Most rock samples from the MJ field have moderate thermal maturity; n-alkane and their

A. Akinlua; N. Torto

2010-01-01

286

Seabed instability simplified model and application in offshore wind turbine  

Microsoft Academic Search

The offshore wind power is increasingly developed, it is essential to study the design technology of the offshore wind turbine foundation, which is crucial to reduce the construction cost of the offshore wind farm. In the design of marine pile foundations, the evaluation of wave-induced seabed stability is quite significant. Based on the mechanical properties of seabed, this article firstly

Zhang Yong-li; Li Jie

2009-01-01

287

Human and organization factors: engineering operating safety into offshore structures  

Microsoft Academic Search

History indicates clearly that the safety of offshore structures is determined primarily by the humans and organizations responsible for these structures during their design, construction, operation, maintenance, and decommissioning. If the safety of offshore structures is to be preserved and improved, then attention of engineers should focus on to how to improve the reliability of the offshore structure ‘system,’ including

Robert G. Bea

1998-01-01

288

Review of offshore wind turbine failures and fault prognostic methods  

Microsoft Academic Search

Wind electricity is a highly promoted energy source all around the world. The number of offshore wind farms, increases gradually because of the high capability of power generation. However, the cost of manufacturing, logistics, installation, grid control and maintenance of offshore wind turbine is high. According to the Condition Monitoring of Offshore Wind Turbine (CONMOW) report of Energy Research Centre

Bill Chun Piu Lau; Eden Wai Man Ma; Michael Pecht

2012-01-01

289

Detection of wind wakes offshore from satellite SAR  

Microsoft Academic Search

A study is presented on the mapping of ocean wind fields for detection of wind wakes downstream of an offshore wind farm. The study is based on ERS-2 Synthetic Aperture Radar (SAR) scenes obtained in 2003 over Horns Reef in the North Sea. A large offshore wind farm (80 wind turbines) is located 14-20 km offshore of Denmark on this

M. B. Christiansen; C. B. Hasager

2004-01-01

290

Challenges on the Road to an Offshore HVDC Grid  

Microsoft Academic Search

This paper discusses the technical challenges for offshore HVDC grids, which is a promising alternative for grid connection of offshore windfarms. The first topic is why HVDC is necessary, and which types of converters there should be used, resulting in a clear recommendation of HVDC based on voltage source converters. There is already offshore experience with VSC HVDC and the

Erik Koldby; Mats Hyttinen

291

Offshore Wind Farm Layout Optimization (OWFLO) Project: Preliminary Results  

Microsoft Academic Search

Optimizing the layout of an offshore wind farm presents a significant engineering challenge. Most of the optimization literature to date has focused on land-based wind farms, rather than on offshore farms. Typically, energy production is the metric by which a candidate layout is evaluated. The Offshore Wind Farm Layout Optimization (OWFLO) project instead uses the levelized production cost as the

Christopher N. Elkinton; James F. Manwell; Jon G. McGowan

292

OFFSHORE WIND FARM LAYOUT OPTIMIZATION (OWFLO) PROJECT: AN INTRODUCTION  

Microsoft Academic Search

Optimizing the layout of an offshore wind farm presents a significant engineering challenge. Most of the optimization literature to date has focused on land-based wind farms, rather than on offshore farms. The conventional method used to lay out a wind farm combines a turbine cost model and a wake model in conjunction with an optimization routine. In offshore environments, however,

C. N. Elkinton; J. F. Manwell; J. G. McGowan

293

Visual impact assessment of offshore wind farms and prior experience  

Microsoft Academic Search

Energy planners have shifted their attention towards offshore wind power generation and the decision is supported by the public in general, which in the literature has a positive attitude towards offshore wind generation. However, globally only a few offshore wind farms are operating. As more wind farms start operating and more people become experienced with especially the visual impacts from

Jacob Ladenburg

2009-01-01

294

Are offshore power plants realistic. [Alternative to nuclear power plants  

Microsoft Academic Search

Offshore fossil-fueled electric power plants offer a positive alternative to nuclear proliferation, a viable technology for providing electricity to coastal cities. Such plants combine new technology from the offshore oil industry with efficient power generation techniques, are cheaper than nuclear plants, and could burn coal or solid waste or a mixture of both. Offshore power plants could utilize ocean water

Adler

1976-01-01

295

A case study of national culture and offshoring services  

Microsoft Academic Search

Purpose – Prior surveys have shown that national culture is a leading cause of problems in offshoring services. The research question posed in this paper centers on how and through what specific decisions national culture affects operational implementation in offshore facilities. Design\\/methodology\\/approach – A particular US service process offshored to Barbados and the Dominican Republic is studied. Ethnographic worker observations

Richard Metters

2008-01-01

296

International Offshore Students' Perceptions of Virtual Office Hours  

ERIC Educational Resources Information Center

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…

Wdowik, Steven; Michael, Kathy

2013-01-01

297

United States Offshore Wind Resource Assessment  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

298

Stratigraphic framework and petroleum potential of Northeastern Baltimore Canyon Trough, Mid-Atlantic Outer Continental Shelf  

SciTech Connect

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurassic through Cenozoic rock-stratigraphic units. The oldest rocks penetrated by exploratory wells are of Late Jurassic age and are correlative to the Scotian Shelf Mohawk, Mic Mac, and Abenaki Formations. The Mohawk(.) sandstone and Mic Mac shale equivalents in the Baltimore Canyon Trough represent lower delta plain to predominantly prodelta environments, and the Abenaki-equivalent limestone represents a shelfmargin carbonate buildup. A destructional phase of the delta is represented by the Naskapi equivalents a calcareous shale. Stratigraphic traps may be present in the Baltimore Canyon Trough Upper Jurassic and Lower Cretaceous deltaic sandstones and shelf-margin carbonates. The deltaic units contain channel and distributary-mouth-bar sandstones, which may be potential reservoirs. The Abenaki stratigraphic-reef trend provides another potential target.

Libby-French, J.

1984-01-01

299

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

SciTech Connect

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.

Moyer, T.C.; Geslin, J.K. [Science Applications International Corp., Golden, CO (United States); Flint, L.E. [U.S. Geological Survey, Yucca Mountain Project, Mercury, NV (United States)

1996-08-01

300

Hierarchical construction of stratigraphic elements in surface-based reservoir models  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

301

Stratigraphic evidence from the Appalachian Basin for continuation of the Taconian orogeny into Early Silurian time  

NASA Astrophysics Data System (ADS)

Traditional interpretations of the Appalachian Basin during Silurian time suggest a period of tectonic stability between Taconian and Acadian orogenies. However, recent interpretations of evidence from deformation and igneous sources in the northern Appalachians indicate Silurian tectonism centered on and near the St. Lawrence promontory and that this tectonism probably effected sedimentation in parts of the Appalachian Basin during much of Silurian time. Of special interest is the tectonism that extended from latest Ordovician into Early Silurian time and the nature of its relationships with known orogenic events. Although evidence and interpretations from deformation and igneous sources have become increasingly well established, there has been little support from the stratigraphic record. Now, however, criteria based on the implications of flexural models, namely the nature and distribution of unconformities, the presence of flexural stratigraphic sequences, and the distribution in time and space of dark-shale-filled foreland basins, provide stratigraphic evidence from the Appalachian Basin that supports Early Silurian (Medinan; early Llandoverian) tectonism related to Taconian orogeny. In particular, the distribution and local angularity of the Ordovician-Silurian or Cherokee unconformity suggest major tectonic influence and a latest Ordovician to Early Silurian inception for that tectonism. An overlying flexural stratigraphic sequence represented by the Lower Silurian Medina Group and the presence of a dark-shale-filled foreland basin reflected by the Power Glen-lower Cabot Head shales support interpretations of flexural subsidence related to deformational loading. Moreover, the distribution in space and time of the foreland basin containing these shales indicates that the basin is more likely a continuation of the northwestwardly shifting trend of earlier Taconian basins than that of later Salinic basins. Although the kinematic regime may be different from that of earlier Taconian tectophases, the stratigraphic evidence supports a northeastward extension of the Taconian orogeny into present-day eastern Canada during Early Silurian time and illustrates the usefulness of flexure-based stratigraphic interpretations in understanding the timing and extent of some orogenies.

Ettensohn, Frank R.; Brett, Carlton E.

2002-01-01

302

Comparative structural reconstruction of the post-breakup succession in conjugated salt and salt-free basins offshore South-America and South-Africa  

NASA Astrophysics Data System (ADS)

This project focuses on the post-breakup tectono-stratigraphic development of large offshore basins along the South American and African continental margins that record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. In this study we show a regional comparison between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin, etc). A sequential reconstruction of tectonic and stratigraphic elements of representative geological transects provides a comprehensive basin-to-basin documentation of the influence of key geological parameters controlling ocean and continental margin development. These include the subsidence development through time, sediment input, flux and storage patterns, salt vs. non-salt systems, carbonate-rich vs. clastics-dominated successions and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development.

Strozyk, Frank; Back, Stefan; Kukla, Peter

2013-04-01

303

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

USGS Publications Warehouse

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

Elder, W. P.

1989-01-01

304

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

USGS Publications Warehouse

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.

Adams, David P.

1976-01-01

305

Cut drydocking costs for offshore rigs  

SciTech Connect

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.

Albaugh, E.K.

1985-07-01

306

Offshore-platform decommissioning perceptions change  

Microsoft Academic Search

The oil and gas industry has seen a change in the perceptions about decommissioning offshore facilities. Now, decommissioning projects are being planned ahead of actual field development, and new concepts derived during decommissioning often are used to provide feedback for new development projects. The current trends and concepts applicable to decommissioning can be summarized as: advanced planning; engineered solutions; research

Twachtman

1997-01-01

307

Response actions at offshore hazardous waste sites  

Microsoft Academic Search

Scores of U.S. offshore continental hazardous wastes sites, including radioactive, bulk industrial chemical, unexploded ordnance, and chemical weapons, as well as sunken vessels containing hazardous cargo have gone uninvestigated as to their potential impact on the marine ecosystem. Only one site investigated, the “Santa Clara I”, with advanced technologies resulted in a successful response action not requiring further attention. Other

J. Lindsay; H. Karl; P. McGillivary; P. Vogt; R. Halls; I. MacDonald; B. Coles

1998-01-01

308

Harmonic modelling of offshore wind farms  

Microsoft Academic Search

The combination of extensive cable networks and wind turbine converters has been identified as a potential cause of resonances. A modelling approach for a doubly fed induction generator and a full power converter fed generator for harmonic penetration studies is developed and discussed. An example offshore wind farm is then studied in the simulation package IPSA using the detailed wind

R. King; J. B. Ekanayake

2010-01-01

309

A New Architecture for Offshore Wind Farms  

Microsoft Academic Search

Offshore wind farms using HVDC links can be positioned a large distance from shore, opening up new opportunities for wind generation. Conventional approaches using 60 Hz generators and transformers are not appropriate in such applications, as they are heavy and result in expensive and complex installation and maintenance issues. This paper proposes an alternative architecture for such wind farms, using

Anish Prasai; Jung-Sik Yim; Deepak Divan; Ashish Bendre; Seung-Ki Sul

2008-01-01

310

A new architecture for offshore wind farms  

Microsoft Academic Search

Offshore wind farms using HVDC links can be positioned a large distance from shore, opening up new opportunities for wind generation. Conventional approaches using 60 hertz generators and transformers are not appropriate in such applications, as they are heavy and result in expensive and complex installation and maintenance issues. This paper proposes an alternative architecture for such wind farms, using

Anish Prasai; A. Bendre; Jung-Sik Yim; Seung-Ki Sul; D. Divan; Frank Kreikebaum

2007-01-01

311

Offshore Investments by Colleges Draw Scrutiny  

ERIC Educational Resources Information Center

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…

Fain, Paul; Wolverton, Brad

2007-01-01

312

Spar buoy escape system for offshore platforms  

Microsoft Academic Search

An offshore platform is shown in position over the seabed. An escape chamber in the form of a spar buoy is mounted on a platform and extends from the platform above the surface of the water to below the surface. A cable also extends between the buoy and an anchor located on the seabed remotely from the platform. When the

Connelly

1985-01-01

313

Tephrochronology offshore Ischia Island, Tyrrhenian sea, Italy  

Microsoft Academic Search

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 \\

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

2010-01-01

314

Offshore Essaouira basin: Geology and hydrocarbon potential  

Microsoft Academic Search

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

H. Jabour; A. Ait Salem

1991-01-01

315

Offshore Corrosion Protection of Wind Farms  

Microsoft Academic Search

The increasing development of offshore Wind Farms brings with it a new level of corrosion problems due to the aggressive marine surroundings. However, this problem has been in existence for almost 40 years with the Oil & Gas production industry which has worked hard to produce satisfactory solutions to these problems. A number of expensive failures in the Oil and

James Thick

316

Solar power satellite offshore rectenna study  

NASA Astrophysics Data System (ADS)

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.

1980-11-01

317

Probability distributions for offshore wind speeds  

Microsoft Academic Search

In planning offshore wind farms, short-term wind speeds play a central role in estimating various engineering parameters, such as power output, extreme wind load, and fatigue load. Lacking wind speed time series of sufficient length, the probability distribution of wind speed serves as the primary substitute for data when estimating design parameters. It is common practice to model short-term wind

Eugene C. Morgan; Matthew Lackner; Richard M. Vogel; Laurie G. Baise

2011-01-01

318

Stochastic Modeling Techniques for Offshore Geohazards  

NASA Astrophysics Data System (ADS)

Much remains to be known about offshore phenomena, despite the potential threat they pose to coastal communities and economically-important offshore infrastructure. The scientific and engineering community has a fairly good grasp of the mechanics governing these geohazards; for instance, we can model tsunami run-ups over entire oceans, evaluate the stability of slopes, and predict the runout of a given landslide. Much of the uncertainty arising in applications of such models stems from the sparsity and error in offshore data. Such datasets are often sparse because the ocean is so large, and contain values with potentially significant measurement error because of the complexities involved in collecting data in such extreme conditions (e.g., sampling sediment under miles of water). Stochastic techniques and statistics quantify these types of uncertainty. In the first chapter of this dissertation, I apply a stochastic optimization method to a geophysical model to achieve estimates of sub-seabed gas concentrations from remotely-sourced seismic reflection data. In the second chapter, I combine geostatistics and first-order, second-moment uncertainty analysis to map the probability of slope failure along the entire U.S. Atlantic margin. My third and final chapter statistically characterizes offshore wind speeds using an unprecedented amount of data collected over the northwestern hemisphere.

Morgan, Eugene C.

319

Primary, Physical Impacts of Offshore Petroleum Developments.  

National Technical Information Service (NTIS)

These studies on the initial physical effects of offshore oil development respond to the need for information on potential petroleum production from the Atlantic and Gulf of Alaskan continental shelves. In the first section of this report, a range of hypo...

1974-01-01

320

Mobile offshore structure for arctic exploratory drilling  

Microsoft Academic Search

An offshore exploratory drilling floatable structure ballastable to rest on a sea floor but to extend above water level when so supported and adapted to withstand arctic ice loads, comprising a substantially vertical wall capable of withstanding arctic ice loads; a structural load bearing bottom rigidly connected to a lower portion of the wall; and a floatable vertically displaceable load

D. R. Hale; J. A. Orndorff Jr; W. A. Owen

1985-01-01

321

Risk analysis for Arctic offshore operations  

SciTech Connect

Offshore exploration for hydrocarbons is being conducted in the near-shore regions of the Beaufort Sea. This activity is expected to be intensified and expanded into the deeper portions of the Beaufort, as well as into the Chukchi Sea. The ice conditions in the Beaufort Sea are very variable, particularly in the deeper water regions. This variability greatly influences the probability of success or failure of an offshore operation. For example, a summer exploratory program conducted from a floating drilling unit may require a period of 60 to 100 days on station. The success of such a program depends on: (a) the time when the winter ice conditions deteriorate sufficiently for the drilling unit to move on station; (b) the number of summer invasions by the arctic ice pack, forcing the drilling unit to abandon station; (c) the rate at which first-year ice grows to the ice thickness limit of the supporting icebreakers; and (d) the extent of arctic pack expansion during the fall and early winter. In general, the ice conditions are so variable that, even with good planning, the change of failure of an offshore operation will not be negligible. Contingency planning for such events is therefore necessary. This paper presents a risk analysis procedure which can greatly benefit the planning of an offshore operation. A floating drilling program and a towing and installation operation for a fixed structure are considered to illustrate the procedure.

Slomski, S.; Vivatrat, V.

1986-04-01

322

New York Offshore Airport Feasibility Study.  

National Technical Information Service (NTIS)

The purpose of the study was to determine the technical and economic feasibility of an offshore airport for the New York metropolitan region. The study included analyses of a series of major tasks and subtasks which affect airport planning including air t...

1972-01-01

323

New York Offshore Airport Feasibility Study.  

National Technical Information Service (NTIS)

The purpose of the study was to determine the technical and economic feasibility of an offshore airport for the New York metropolitan region. The study included analyses of a series of major tasks and substasks which affect airport planning including air ...

L. Lerner M. A. Graham

1973-01-01

324

Reliability model of large offshore wind farms  

Microsoft Academic Search

For investors of wind farms projects, it is indispensable to get reliable prognosis of the expected energy produced per year, taking into account technical failures and the stochastic characteristic of the wind. This applies especially for offshore wind farms with higher installation costs and difficult maintenance conditions. The repair of components located on sea may take many days or even

E. Spahic; A. Underbrink; V. Buchert; J. Hanson; I. Jeromin; G. Balzer

2009-01-01

325

Sea loads on ships and offshore structures  

Microsoft Academic Search

The book introduces the theory of the structural loading on ships and offshore structures caused by wind, waves and currents, and goes on to describe the applications of this theory in terms of real structures. The main topics described are linear-wave induced motions, loads on floating structures, numerical methods for ascertaining wave induced motions and loads, viscous wave loads and

O. M. Faltinsen

1990-01-01

326

Human Rights, Academic Freedom, and Offshore Academics  

ERIC Educational Resources Information Center

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)…

Ross, Andrew

2011-01-01

327

Protecting the Sable Offshore Energy Project  

Microsoft Academic Search

A project to develop one of the largest remaining known natural gas deposits in North America currently is underway in the Atlantic waters of Canada. The Sable Offshore Energy Project (SOEP) is a $3 billion venture to develop six major natural gas fields that lie 10 to 40 km north of the edge of the Scotian Shelf in waters 20

Cederquist

1999-01-01

328

3 MW class offshore wind turbine development  

Microsoft Academic Search

This paper introduces the design and development of a 3MW class offshore wind turbine (WinDS3000). The design has been carried out by considering high reliability, availability, maintainability and serviceability (RAMS) for the wind class TC Ia. An integrated drive train design, which has an innovative three stage gearbox, has been introduced to minimize nacelle weight of the wind turbine and

Jiwoong Park; Jeongil Kim; Youngho Shin; Jeonghoon Lee

2010-01-01

329

Canada's first offshore oil: what now  

Microsoft Academic Search

Canada's eastern offshore is not only a big exploration theater, but geologically it is among the most promising in the world. A major find here, especially in the S. parts nearest markets, will have greater impact on the world petroleum scene than on equal find almost anywhere else. Mobil Oil Canada has completed what promises to be a commercial oil

Heise

1971-01-01

330

Protective shroud for offshore oil wells  

Microsoft Academic Search

This invention provides means and methods for servicing offshore oil wells under routine and emergency conditions. Thus, a protective shroud surrounding the well site and provided with pumping means can be used to recover spilled oil, store oil, extinguish blowouts and fires, and protect rigs, platforms and personnel. A hollow shroud structure, preferably of circular cross section surrounding an oil

A. O. Johnson; D. Personette

1981-01-01

331

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...

332

On the stratigraphic integrity of leaf-wax biomarkers in loess paleosols  

NASA Astrophysics Data System (ADS)

Paleoenvironmental and paleoclimate reconstructions based on molecular proxies, such as those derived from leaf-wax biomarkers, in loess-paleosol sequences represent a promising line of investigation in Quaternary research. The main premise of such reconstructions is the synsedimentary deposition of biomarkers and dust, which has become a debated subject in recent years. This study uses two independent approaches to test the stratigraphic integrity of leaf-wax biomarkers: (i) long-chain n-alkanes and fatty acids are quantified in two sediment-depth profiles in glacial till on the Swiss Plateau, consisting of a Holocene topsoil and the underlying B and C horizons. Since glacial sediments are initially very poor in organic matter, significant amounts of leaf-wax biomarkers in the B and C horizons of those profiles would reflect postsedimentary root-derived or microbial contributions. (ii) Compound-specific radiocarbon measurements are conducted on n-alkanes and n-alkanoic (fatty) acids from several depth intervals in the loess section "Crvenka", Serbia, and the results are compared to independent estimates of sediment age. We find extremely low concentrations of plant-wax n-alkanes and fatty acids in the B and C horizons below the topsoils in the sediment profiles. Moreover, compound-specific radiocarbon analysis yields plant-wax 14C ages that agree well with published luminescence ages and stratigraphy of the Serbian loess deposit. Both approaches confirm that postsedimentary, root-derived or microbial contributions are negligible in the two investigated systems. The good agreement between the ages of odd and even homologues also indicates that reworking and incorporation of fossil leaf waxes is not particularly relevant either.

Häggi, C.; Zech, R.; McIntyre, C.; Zech, M.; Eglinton, T. I.

2014-05-01

333

Wave Slamming on Offshore Structures.  

National Technical Information Service (NTIS)

Experimental and theoretical work on the slamming of circular cylinders is surveyed. Data are included from controlled drop tests. The influence of inclined impact and beam dynamics on the resulting stresses is calculated for a wide range of wave conditio...

B. L. Miller

1980-01-01

334

Petroleum prospects for offshore sedimentary basins in the eastern Papua New Guinea and Solomon Islands regions  

SciTech Connect

Intra-arc basins in the Buka-Bougainville region of Papua New Guinea and in the Solomon Islands contain thick sedimentary sequences that may be prospective for petroleum. The Queen Emma basin, between Bougainville and New Ireland, contains as much as 8 km of deformed Oligocene and younger strata. The Central Solomons Trough, which underlies New Georgia Sound, is a composite intra-arc basin that contains late Oligocene and younger strata as much as 7 km thick. Farther east, beneath Indispensable Strait, the down-faulted Indispensable basin locally contains as much as 5.4 km of Miocene( ) and younger strata, and the offshore part of Mbokokimbo basin off eastern Guadalcanal includes 6 km or more of late Miocene and younger strata. All of these basins have some of the attributes necessary to generate and trap petroleum. Structural and stratigraphic traps are common, including faulted anticlines, sedimentary wedges, and carbonate reefs and reef-derived deposits on submarine ridges and along the basin margins. The thickness of the basin deposits ensures that some strata are buried deeply enough to be within the thermal regime required for hydrocarbon generation. However, little source or reservoir rock information is available because of the lack of detailed surface and subsurface stratigraphy. Moreover, much of the basin sediment is likely to consist of volcaniclastic material, derived from uplifted volcanogenic rocks surrounding the basins, and may be poor in source and reservoir rocks. Until additional stratigraphic information is available, analysis of the petroleum potential of these basins is a matter of conjecture.

Bruns, T.R.; Vedder, J.G. (Geological Survey, Menlo Park, CA (USA))

1990-06-01

335

Plio-Pleistocene sequence stratigraphic architecture of the eastern Niger Delta: A record of eustasy and aridification of Africa  

Microsoft Academic Search

This study synthesizes the stratigraphic behavior of the whole eastern Niger Delta during the Plio-Pleistocene and discusses controls on deposition by eustasy, subsidence and sediment supply at various scales. The sequence stratigraphic architecture is determined by integrating the whole sedimentary system from the coastal plain down to the abyssal plain. We combined structural geology, sedimentology biostratigraphy, and seismic stratigraphy. Data

P. Jermannaud; D. Rouby; C. Robin; Thierry Nalpas; François Guillocheau; Stéphane Raillard

2010-01-01

336

Neoproterozoic stratigraphic comparison of the Lesser Himalaya (India) and Yangtze block (south China): Paleogeographic implications  

Microsoft Academic Search

Recent studies of terminal Neoproterozoic rocks (ca. 590 543 Ma) in the Lesser Himalaya of northwestern India and the Yangtze block (south China) reveal remarkably similar facies assemblages and carbonate platform architecture, with distinctive karstic unconformities at comparable stratigraphic levels. These similarities suggest that south China may have been located close to northwestern India during late Neoproterozoic time, an interpretation

Ganqing Jiang; Linda E. Sohl; Nicholas Christie-Blick

2003-01-01

337

Beyond stratigraphic noise: Unraveling the evolution of stratified assemblages in faunalturbated sites  

Microsoft Academic Search

This study explores the stratigraphic evolution of archaeological assemblages in faunaltur- bated sites. These sites are sometimes described as having limited archaeological value because of varying degrees of occupation mixing. It is argued here that the vertical distribution of assemblages is predictable in faunalturbated contexts. Understanding this vertical evolution may lead to a better assessment of the archaeological potential of

Eugène Morin

2006-01-01

338

The Modified Gap Excess Ratio (GER*) and the Stratigraphic Congruence of Dinosaur Phylogenies  

Microsoft Academic Search

Palaeontologists routinely map their cladograms onto what is known of the fossil record. Where sister taxa first appear as fossils at different times, a ghost range is inferred to bridge the gap between these dates. Some measure of the total extent of ghost ranges across the tree underlies several indices of cladistic\\/stratigraphic congruence. We investigate this congruence for 19 independent,

MATTHEW A. WILLS; PAUL M. BARRETT; Julia Heathcote

2008-01-01

339

Genesis of limestone megabreccias and their significance in carbonate sequence stratigraphic models: a review  

Microsoft Academic Search

A re-appraisal of the factors controlling the deposition of carbonate megabreccias and their sequence stratigraphic significance is presented based on an examination of the mechanisms for instigating carbonate seafloor slope instability and a review of the depositional settings of these distinctive rock deposits. Limestone megabreccias have classically been interpreted as formed by the catastrophic collapse of high-angle metastable ‘oversteepened’ carbonate

Guy H. Spence; Maurice E. Tucker

1997-01-01

340

Stratigraphic framework and petroleum potential of Northeastern Baltimore Canyon Trough, Mid-Atlantic Outer Continental Shelf  

Microsoft Academic Search

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurassic through Cenozoic rock-stratigraphic units. The oldest rocks penetrated by exploratory wells are of Late Jurassic age and are correlative to the Scotian Shelf Mohawk, Mic Mac, and Abenaki Formations. The Mohawk(.) sandstone and Mic

Libby-French

1984-01-01

341

Stratigraphic framework and petroleum potential of northeastern Baltimore Canyon Trough, mid-Atlantic outer Continental Shelf  

Microsoft Academic Search

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurasic through Cenozoic rock-stratigraphic units. Most of the units are lithologically similar to formations on the Scotian Shelf and are, therefore, considered in this study to be the Scotian Shelf homotaxial equivalents. The Mohawk(.) sandstone

Libby-French

1984-01-01

342

Regional correlations in the South Caspian Sea -implications for stratigraphic nomenclature  

SciTech Connect

Regional Correlations in the South Caspian Sea - Implications for Stratigraphic Nomenclature Detailed sequence boundary correlations in the South Caspian sea have led to a better understanding of the relationships between stratigraphic units identified in wells throughout the basin. With the aid of synthetic seismograms, used to tie the logs to the seismic data, lithologic units have been identified seismically and have been mapped across the basin. The synthetic seismograms were created from pseudo-sonic logs which were transformed from resistivity logs with the Faust equation. Checkshots and VSP surveys supplied the velocity control. The sequence boundary correlations revealed substantial facies changes across the basin and led to the creation of a new stratigraphic correlation chart which relates local formation names to their time correlative boundaries. A recognition of these facies changes has led to a better understanding of the lithologic relationships within the basin, the depositional history of the basin, and the source and distribution of potential reservoir sands. Previous well log correlations, made primarily by matching tops of sand and shale sequences, frequently crossed sequence boundaries mapped from seismic data. Lithologic units, deposited under similar geologic conditions, often looked the same but were not time equivalent. Seismic sequence analyses have shown that tectonic movements, as evidenced by rising domes, created barriers to sediment distribution and led to pronounced thickness changes on opposite sides of a high. New log correlations, incorporating these concepts, are helping to unravel the complex structural and stratigraphic history of the South Caspian Sea.

Murphy, J. [Chevron, San Ramon, CA (United States)] Rukhsara, K. [State Oil Company, Baku (Kazakhstan)

1995-08-01

343

Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia  

Microsoft Academic Search

Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin

J. Desmond Clark; Yonas Beyene; Giday WoldeGabriel; William K. Hart; Paul R. Renne; Henry Gilbert; Alban Defleur; Gen Suwa; Shigehiro Katoh; Kenneth R. Ludwig; Jean-Renaud Boisserie; Berhane Asfaw; Tim D. White

2003-01-01

344

Time Relations and Structural-Stratigraphic Patterns in Ophiolite Accretion, West Central Klamath Mountains, California  

Microsoft Academic Search

New geochronological data and published structural and stratigraphic data show that two distinctly different ophiolitic assemblages formed in general proximity to one another at nearly the same time and were subsequently imbricated along a regional thrust zone. The Josephine ophiolite constitutes a complete oceanic crust and upper mantle sequence which lies within the western Jurassic belt of the Klamath province.

Jason B. Saleeby; Gregory D. Harper; Arthur W. Snoke; Warren D. Sharp

1982-01-01

345

Postglacial evolution of Saanich Inlet, British Columbia: results of physical property and seismic reflection stratigraphic analysis  

Microsoft Academic Search

Seismic stratigraphic analysis combined with results from ODP Leg 169S deep ocean drilling within Saanich Inlet to depths greater than 100m below the seafloor provided an opportunity to study the post-glacial development of the inlet in a quantitative manner. The seismic stratigraphy of Saanich Inlet is consistent with the general stratigraphy established for southwestern British Columbia. Sediment physical property data

D. C Mosher; K Moran

2001-01-01

346

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

SciTech Connect

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.

Rubin, P A; Lemiszki, P J

1992-01-01

347

Multi-scale alluvial fan heterogeneity modeled with transition probability geostatistics in a sequence stratigraphic framework  

Microsoft Academic Search

The complexity of alluvial fan depositional systems makes detailed characterization of their heterogeneity difficult, yet such detailed characterizations are commonly needed for construction of reliable groundwater models. The transition probability geostatistical approach provides a means to quantify the distribution of hydrofacies in the subsurface. However, a key assumption used in this and other geostatistical approaches is that of stationarity. Stratigraphic

G. S. Weissmann; G. E. Fogg

1999-01-01

348

The K\\/T boundary at Beloc (Haiti): Compared stratigraphic distributions of the boundary markers  

Microsoft Academic Search

At Beloc, Haiti the Cretaceous-Tertiary boundary (KTB) is characterized by a spherule bed containing glass particles. These particles are considered by some authors as remains of tektites resulting from a nearby impact. However, because of the stratigraphic complexity of the Beloc sections the genetic link between the KTB cosmic event and the spherule bed is not obvious. In this paper,

Hugues Leroux; Robert Rocchia; Laurence Froget; Xavier Orue-Etxebarria; Jean-Claude Doukhan; Eric Robin

1995-01-01

349

REVISION OF SOME STRATIGRAPHIC NAMES BETWEEN THE LOWER AND MIDDLE KITTANNING COALS IN EASTERN OHIO  

Microsoft Academic Search

Recent observations on the strata between the Lower and Middle Kittanning Coals in eastern Ohio indicate that some additions and corrections in stratigraphic names are in order. Modifications pertain not only to beds associated with the Kittanning Coals but also to those in the intervening Strasburg cyclothem. Certain of these changes have already been noted (Sturgeon and associates, 1958: 64,

MYRON T. STURGEON; RICHARD M. DELONG

350

Seismic stratigraphic study of two Oxfordian carbonate sequences, eastern Saudi Arabia  

Microsoft Academic Search

In this case study, seismic stratigraphic interpretation techniques were used to map facies changes and develop a depositional model for two Oxfordian carbonate sequences of eastern Saudi Arabia. Well data and regional geology indicate that the two sequences, R1 and R2, were deposited on a broad carbonate platform and undergo a lateral transition from grainstone to basinal mudstone within the

G. S. Langdon; S. J. Malecek

1987-01-01

351

Geologic evolution of a Pliocene-Pleistocene salt-withdrawal minibasin: Eugene Island Block 330, offshore Louisiana  

SciTech Connect

The spatial and temporal distributions of reservoir sands are documented within the context of an evolving Plicoene-Pleistocene salt-withdrawal shelf minibasin. The Eugene Island Block 330 field, a giant oil and gas field in offshore Louisiana, is contained within the minibasin. Based on the stratigraphic and structural analyses, we present a sequence-stratigraphic and tectonic-stratigraphic model for reservoir prediction in complex shelf Gulf of Mexico minibasins. The minibasin evolved in three phases: prodelta, proximal deltaic, and fluvial. Sediment accumulation and fault slip rates were high as thick sequences of deltaic sands were deposited adjacent to the fault system. During the final fluvial phase, salt withdrawal waned; consequently, the creation of accommodation space within the minibasin ceased. The basin infilled and, during lowstands, deltaic systems prograded southward. Unconformities developed in the minibasin during these lowstands. During transgressions, thick packages of shallow-water deltaic and fluvial sands (capped by shales) were deposited on top of the unconformities. One major reservoir, the Lentic, was deposited during the prodelta phase. The hydrocarbons are trapped by deep early faults within this geopressured sand. Most of the major exploited reservoirs of the Block 330 field were deposited in the proximal deltaic phase. Reservoirs deposited in this phase are laterally extensive proximal deltaic sands that have good lateral seals because of the amount of fault activity that occurred in this interval. Only one major reservoir was deposited in the fluvial phase. This reservoir was deposited while the basin-bounding faults were still active, so the reservoir has four-way closure. Sands deposited later in the fluvial phase tend to lack lateral seals and structural closure.

Alexander, L.L. [Cornell Univ., Ithaca, NY (United States); Flemings, P.B. [Pennsylvania State Univ., University Park, PA (United States)

1995-12-01

352

Divergent evolutionary processes associated with colonization of offshore islands.  

PubMed

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

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

353

Southern Mozambique basin: most promising hydrocarbon province offshore eat Africa  

SciTech Connect

Recent offshore acquisition of 12,800 km (8,000 mi) of seismic reflection data, with gravity and magnetic profiles encompassing the southern half of the Mozambique basin, reveals new facets of the subsurface geology. Integrated interpretation of these new geophysical data with old well information results in the development of depositional and tectonic models that positively establish the hydrocarbon potential of the basin. The recent comprehensive interpretation affords the following conclusions. (1) Significant oil shows accompany wet gas discoveries suggest that the South Mozambique basin is a mature province, as the hydrocarbon associations imply thermogenic processes. (2) Super-Karoo marine Jurassic sequences have been encountered in Nhamura-1 well onshore from the application of seismic stratigraphy and well correlation. (3) Steeply dipping reflectors truncated by the pre-Cretaceous unconformity testify to significant tectonic activity preceding the breakup of Gondwanaland. Hence, preconceived ideas about the depth of the economic basement and the absence of mature source rocks of pre-Cretaceous age should be revised. (4) Wildcats in the vicinity of ample structural closures have not been, in retrospect, optimally positioned nor drilled to sufficient depth to test the viability of prospects mapped along a major offshore extension of the East African rift system delineated by this new survey.

De Buyl, M.; Flores, G.

1984-09-01

354

Post-glacial sea-level history for SW Ireland (Bantry Bay) based on offshore evidence  

NASA Astrophysics Data System (ADS)

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.

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

355

Topographic Growth, the Development of Rivers and Implications for the Marine Stratigraphic Record in SE Asia (Invited)  

NASA Astrophysics Data System (ADS)

The sediments accumulating in the marginal seas of Southeast Asia are largely delivered from the major rivers that flow from the eastern flank of the Tibetan Plateau. At the regional scale the rate of sediment delivery is controlled by the intensity of the summer monsoon, but in individual deltas the composition of sediment and rates of sedimentation are also affected by headwater capture. Recent data now indicate that significant transfer drainage between rivers occurred around the end of the Oligocene-early Miocene (~24 Ma). This key period reflects the start of significant uplift in southeastern Tibet, coupled with extension and subsidence in the marginal seas of eastern Asia driven by the rollback of the Pacific plate. U-Pb ages of zircon sand grains in the Yangtze River show that this system was close to its present configuration before 23 Ma, correlating with large-scale change in the Red River during the latter part of the Oligocene. At the same time, the Irrawaddy loses its connection with the Yarlung Tsangpo, which dates back to shortly after India-Asia collision. The Yarlung Tsangpo together with the Indus appears to be unique in forming in the collisional suture between Asia (or an intraoceanic arc) and India shortly after 50 Ma. Once these two rivers are established in the suture zone it is impossible to disrupt their flow as a result of tectonically driven uplift, but it is only in Southwest Asia that the marine record would span the entire Cenozoic history of uplift and erosion, as preserved in the Indus Fan. In contrast, the more gradual tilting of Eastern Asia towards the east through the Cenozoic has resulted in the large-scale disruption noted in the deltas. Diversion of large volumes of clastic sediment from one delta to another has implications for how we interpret the deep-sea sediment record in each location and is of commercial interest in hydrocarbon exploration in changing the availability of reservoir sands on continental margins in ways that are unrelated to either of the local tectonics or regional climate change. Only the Pearl River appears to be unaffected by the evolving topography. Provenance in its offshore basins indicates a constant source in southern China, albeit one that expands gradually inland after the rifting of the South China Sea, but without any major capture events on the scale seen in other Asian river systems. Presently the origin of the Mekong is the most enigmatic, because the marine stratigraphic record suggests its initiation during the late Miocene, at least in the present position.

Clift, P. D.; Zheng, H.

2013-12-01

356

Effect of Lateral Rigidity of Offshore Piles Using Proposed p-y Curves in Marine Clay  

Microsoft Academic Search

The load distribution and deformation of offshore piles are investigated using experimental tests and a numerical analysis. Special attention is given to the soil-pile rigidity of laterally loaded piles. Rigid-and flexible-pile analyses were conducted for comparison. A framework for determining the lateral load transfer curve (p-y curve) is proposed from field and laboratory model tests. A numerical analysis that takes

Youngho Kim; Sangseom Jeong; Jinoh Won

2009-01-01

357

EPA issues offshore air pollution regulations  

SciTech Connect

This paper reports that the Environmental Protection Agency has issued regulations equalizing offshore air pollution rules with onshore standards except in the Gulf of Mexico. The rules hold platforms and drilling rigs within 25 miles of states' seaward boundaries to the same state, local, and federal requirements as if they were located in the corresponding onshore areas. If EPA finds state regulations are adequate, it will delegate to the coastal state the implementation and enforcement authority for the OCS rules. Air emissions sources more than 25 miles offshore will be subject only to federal requirements. EPA said within 2 years the rules will result in significant benefits to certain onshore areas currently violating smog standards.

Not Available

1992-08-31

358

Offshore desulfurization unit permits gas lift operations  

SciTech Connect

This paper reports on the installation of a desulfurization unit for the Tchibouela oil field, offshore Congo, which allowed produced low-pressure associated gas containing CO{sub 2} to be kept for gas lift operations while, for safety reasons, the large volume of H{sub 2}S at low pressure was removed prior to compression. Since October 1989, the world's first offshore amine sweetening unit has worked satisfactorily and continues to prove that it is an attractive production alternative. For desulfurization, a selective methyldiethanolamine (MDEA) process, developed by Elf Aquitaine, was chosen because it was the only process that met the required specifications at a low pressure of 3.5 bar (51 psi).

Cabes, A.; Elgue, J.; Tournier-Lasserve, J. (Societe Nationale Elf Aquitaine Paris (FR))

1992-01-13

359

New technology emphasizes international offshore effort  

SciTech Connect

While the offshore industry is focusing its major development efforts on the deeper waters of the US Gulf, West Africa and Brazil, technology has not stood still in the world`s many other established and frontier offshore development areas. These selected items drawn from contributions by UK companies and a major joint-venture development in Eastern Canada emphasize this effort. Included here are: (1) announcement of a major six-field, 3 Tcf gas development off Nova Scotia`s Sable Island and award of two drilling contracts; (2) a comprehensive study of mobile production units in the UK by Smith Rea Energy Analysts; (3) four applications of an option to high-pressure swivels on an FPSO with multiple subsea inlet lines; (4) a contract to supply a DC bus drive for 17 ESPs on Texaco`s Captain field; and (5) review of an environmental study of the Falkland Islands in preparation for exploration activity.

NONE

1997-07-01

360

Floating ice platforms: offshore oil exploration  

Microsoft Academic Search

Exploratory drilling offshore in the Canadian Arctic Islands in water depths of 200-1300 ft from floating platforms of thickened ice has proven very successful, reports Fenco Consultants Ltd. Designs based on elastic-plate theory have produced strong platforms that behaved much as predicted. In designing the platforms, Fenco used reduced-modulus concepts to estimate creep effects and long-term deflections, making possible the

D. M. Masterson; H. R. Kivisild

1980-01-01

361

Rig utilization rises as offshore drilling recovers  

SciTech Connect

The world offshore drilling outlook for 1984 is one of cautious optimism. There are bright spots, particularly in the U.S. Gulf Coast, where huge amounts of new federal acreage became available to drillers in 1983 and 1984. Figures from the May and August 1983 federal Gulf of Mexico sales are shown. Many new discoveries, including those in Matagorda Island and in Eugene Island Block 315, continue to enhance the outlook.

Brundage, H.T.

1984-02-01

362

Protective riser-conductor for offshore structures  

SciTech Connect

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.

Rutherford, D. A.; Albers, G. P.

1985-07-09

363

Mobile offshore structure for arctic exploratory drilling  

SciTech Connect

An offshore exploratory drilling floatable structure ballastable to rest on a sea floor but to extend above water level when so supported and adapted to withstand arctic ice loads, comprising a substantially vertical wall capable of withstanding arctic ice loads; a structural load bearing bottom rigidly connected to a lower portion of the wall; and a floatable vertically displaceable load bearing structural deck inside the wall.

Hale, D. R.; Orndorff Jr., J. A.; Owen, W. A.

1985-04-23

364

CATHODIC PROTECTION RETROFIT OF AN OFFSHORE PIPELINE  

Microsoft Academic Search

Cathodic protection (CP) anodes and corrosion coating on two offshore pipelines were damaged during deep water installation. In-situ methods for deep-water inspection and repair of the pipelines` CP and coating systems were developed and used. High-pressure natural gas Pipeline. A design was 5.6 miles of 8.625 in. OD by 0.406 in. W.T. API SL, Grade X-42, seamless line pipe. Pipeline

Robert Winters; Alan Holk

1997-01-01

365

Bedout basement rise, offshore northwestern Australia: evidence of an unshocked mafic volcanic hyaloclastite volcanic breccia  

NASA Astrophysics Data System (ADS)

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.

Glikson, A.

2004-12-01

366

Development and application of oil-spill risk assessment model for offshore pipeline  

NASA Astrophysics Data System (ADS)

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.

Lu, Yan; Wang, Jia; Wei, Wenpu; Yang, Yong; An, Wei

2014-06-01

367

Shallow stratigraphic control on pockmark distribution in north temperate estuaries  

USGS Publications Warehouse

Pockmark fields occur throughout northern North American temperate estuaries despite the absence of extensive thermogenic hydrocarbon deposits typically associated with pockmarks. In such settings, the origins of the gas and triggering mechanism(s) responsible for pockmark formation are not obvious. Nor is it known why pockmarks proliferate in this region but do not occur south of the glacial terminus in eastern North America. This paper tests two hypotheses addressing these knowledge gaps: 1) the region's unique sea-level history provided a terrestrial deposit that sourced the gas responsible for pockmark formation; and 2) the region's physiography controls pockmarks distribution. This study integrates over 2500 km of high-resolution swath bathymetry, Chirp seismic reflection profiles and vibracore data acquired in three estuarine pockmark fields in the Gulf of Maine and Bay of Fundy. Vibracores sampled a hydric paleosol lacking the organic-rich upper horizons, indicating that an organic-rich terrestrial deposit was eroded prior to pockmark formation. This observation suggests that the gas, which is presumably responsible for the formation of the pockmarks, originated in Holocene estuarine sediments (loss on ignition 3.5–10%), not terrestrial deposits that were subsequently drowned and buried by mud. The 7470 pockmarks identified in this study are non-randomly clustered. Pockmark size and distribution relate to Holocene sediment thickness (r2 = 0.60), basin morphology and glacial deposits. The irregular underlying topography that dictates Holocene sediment thickness may ultimately play a more important role in temperate estuarine pockmark distribution than drowned terrestrial deposits. These results give insight into the conditions necessary for pockmark formation in nearshore coastal environments.

Brothers, Laura L.; Kelley, Joseph T.; Belknap, Daniel F.; Barnhardt, Walter A.; Andrews, Brian D.; Legere, Christine; Hughes-Clarke, John E.

2012-01-01

368

26th Annual offshore technology conference: 1994 Proceedings  

SciTech Connect

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.

Not Available

1994-01-01

369

The public's trust in scientific claims regarding offshore oil drilling.  

PubMed

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

Carlisle, Juliet E; Feezell, Jessica T; Michaud, Kristy E H; Smith, Eric R A N; Smith, Leeanna

2010-09-01

370

30 CFR 251.7 - Test drilling activities under a permit.  

Code of Federal Regulations, 2010 CFR

...vicinity of the proposed test to the total depth of the proposed test well; and (vi...on the area: (A) Geology; (B) Physical oceanography...Regional Director for review. (ii) If the...commencing deep stratigraphic test drilling...

2009-07-01

371

30 CFR 251.7 - Test drilling activities under a permit.  

Code of Federal Regulations, 2010 CFR

...vicinity of the proposed test to the total depth of the proposed test well; and (vi...on the area: (A) Geology; (B) Physical oceanography...Regional Director for review. (ii) If the...commencing deep stratigraphic test drilling...

2010-07-01

372

The tectono-stratigraphic evolution of basement highs in hyper extended deep-water rifted margins : the example of the Briançonnais domain in the Alps and comparisons with modern analogues  

NASA Astrophysics Data System (ADS)

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. Péron-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 Briançonnais domain in the Alps. To achieve our goal we propose to review the existing structural, stratigraphic and age data from the whole Briançonnais domain (from Liguria/Italy, across the French Alps to Grisons in Switzerland). We propose to construct key tectonic sections across the Briançonnais 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 Briançonnais. 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 Briançonnais domain in the French Alps and a comparisons with seismically imaged basement highs imaged offshore Newfoundland.

Haupert, Isabelle; Manatschal, Gianreto; Unternehr, Patrick; Decarlis, Alessandro

2013-04-01

373

Calibration and Validation of a Spar-Type Floating Offshore Wind Turbine Model using the FAST Dynamic Simulation Tool: Preprint  

SciTech Connect

In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states.

Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

2012-11-01

374

Remote stratigraphic analysis: Combined TM and AIS results in the Wind River/Bighorn Basin area, Wyoming  

NASA Technical Reports Server (NTRS)

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.

Lang, H. R.; Paylor, E. D.; Adams, S.

1985-01-01

375

Pacific offshore record of plinian arc volcanism in Central America: 3. Application to forearc geology  

NASA Astrophysics Data System (ADS)

Sediment gravity cores collected on the Pacific slope and incoming plate offshore Central America reach up to 400 ka back in time and contain numerous ash layers from plinian eruptions at the Central American Volcanic Arc. The compositionally distinct widespread ash layers form a framework of marker horizons that allow us to stratigraphically correlate the sediment successions along and across the Middle America Trench. Moreover, ash layers correlated with 26 known eruptions on land provide absolute time lines through these successions. Having demonstrated the correlations in part 1, we here investigate implications for submarine sedimentary processes. Average accumulation rates of pelagic sediment packages constrained by bracketing tephras of known age range from ˜1-6 cm/ka on the incoming plate to 30-40 cm/ka on the continental slope. There are time intervals in which the apparent pelagic sedimentation rates significantly vary laterally both on the forearc and on the incoming plate where steady conditions are usually expected. A period of unsteadiness at 17-25 ka on the forearc coincides with a period of intense erosion on land probably triggered by tectonic processes. Unsteady conditions on the incoming plate are attributed to bend faulting across the outer rise triggering erosion and resedimentation. Extremely low apparent sedimentation rates at time intervals >50-80 ka suggest stronger tectonic activity than during younger times and indicate bend faulting is unsteady on a longer timescale. Submarine landslides are often associated with ash layers forming structurally weak zones used for detachment. Ash beds constrain ages of >60 ka, ˜19 ka, and <6 ka for three landslides offshore Nicaragua. Phases of intense fluid venting at mud mounds produce typical sediments around the mound that become covered by normal pelagic sediment during phases of weak or no activity. Using intercalated ash layers, we determine for the first time the durations (several hundred to 9000 years) of highly active periods in the multistage growth history of mud mounds offshore Central America, which is essential to understand general mud-mound dynamics.

Kutterolf, S.; Freundt, A.; Schacht, U.; Bürk, D.; Harders, R.; MöRz, T.; PeréZ, W.

2008-02-01

376

Stratigraphic framework for the late Pleistocene in the northwest Pacific Ocean  

NASA Astrophysics Data System (ADS)

Analyses of the relative abundance of Cycladophora davisiana in 10 northwest Pacific deep-sea cores show that the species exhibits abundance variations during the late Pleistocene (?450,000 years) comparable to those in the subantarctic and North Atlantic. Comparison of the C. davisiana curves in the cores with tephra-stratigraphic and biostratigraphic datum levels indicates that the major features of the C. davisiana records are synchronous within the northwest Pacific. Calculated ages for the most recent abundance peak and a distinctively low abundance interval of the C. davisiana curve are similar to the estimated ages for the last glacial and interglacial maxima, respectively. With the development of a detailed stratigraphic framework for late Pleistocene northwest Pacific sediments we have been able to revise the estimated ages of the upper limits of Lychnocanium grande, the Rhizosolenia complex, and Druppatractus acquilonius to 49,000, 276,000, and 329,000 y B.P., respectively.

Morley, Joseph J.; Hays, James D.; Robertson, James H.

1982-12-01

377

Youngest Toba Tuff in the Son Valley, India: a weak and discontinuous stratigraphic marker  

NASA Astrophysics Data System (ADS)

Investigation of the climatic and environmental impacts of the Youngest Toba Tuff (YTT, ˜74 ka BP) eruption of Toba volcano, Sumatra, is crucial for understanding the consequences of the eruption for contemporaneous human populations. The Middle Son Valley, in India, was the first locality on the Indian subcontinent where the YTT was reported. The ash bed forms a discontinuous layer stretching for over 30 km along the river. Here we report on the stratigraphic contexts of YTT ash layers in alluvial deposits of the Middle Son Valley, in order to reconstruct the taphonomy of the ash deposits and the dynamic of their deposition. Although the distal ash has been studied since the 1980s, its stratigraphic integrity and the mechanisms and pathways involved in its transport and deposition have bit previously been assessed. We find that the YTT occurrences in the Middle Son Valley may not be reliable chronostratigraphical markers for millennial scale palaeoenvironmental reconstruction.

Gatti, E.; Durant, A. J.; Gibbard, P. L.; Oppenheimer, C.

2011-12-01

378

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

379

Seismic modeling for gas field development in offshore Niger Delta: A case history  

SciTech Connect

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.

Idowu, A.O. (Nigerian National Petroleum Corp., Lagos (Nigeria))

1994-07-01

380

Computer program for stratigraphic correlation of Devonian shales in Appalachian basin  

SciTech Connect

A computer program has been written to perform graphic and computational functions related to stratigraphic correlation. Stratigraphic information is retrieved from a data base and used to interpolate formation tops between wells. A stratigraphic cross section can then be drawn on a graphics terminal. Kriging is employed in the interpolation to control smoothing. The user can stipulate which wells are included in the cross section, or ask for wells near a specific location or near a specific well. The cross section and other output from the program can be used to determine pay zones that were not correctly interpreted by a driller, to confirm a stratigrapher's correlations, and to find anomalous information in the data base. Estimated tops can be stored in the data base from within the program. Additional graphic activities include drawing a map of well locations and a graphic comparison of a strip log drawn from user-entered driller's lithologic tops and the interpolated tops. The driller's tops and interpolated tops can be matched by the program. The user can choose to turn off the graphics and just interpolate tops for each well on a list provided by the user. If some tops are known in a well, these can be used to interpolate the remaining tops. The base of the Berea Sandstone is commonly used. Accuracy of the interpolations increases as more known tops are used. The program is written in FORTRAN, and uses PLOT 10 Graphical Kernal System. It runs on a VAX 11/750. A Tektronix 4207 color terminal is needed unless the user opts for no graphics.

Timberlake, K.; Hohn, M.; Kite, S.; Behling, M.C.

1988-08-01

381

GNULEX - new online USGS database of stratigraphic nomenclature for US western interior  

SciTech Connect

Accurate and up-to-date information on the definitions of stratigraphic units is essential to both industry and academic activities in the earth sciences. In order to encourage accurate use of stratigraphic nomenclature, they are compiling a new database - GNULEX - which contains comprehensive information on stratigraphic units of the US Western interior (from the Mississippi River to the western borders of Idaho, Utah, and Arizona). The information is from published reports of all major earth science journals dating from the first published use of the unit to the present day. A user selects records either by stratigraphic unit name or by user-specified attributes. These attributes include age (era, period, epoch, or stage), formal rank, state, geologic province or basin, lithologic type, author, and type of information (biostratigraphic dating, isotopic dating, etc) - all attributes may be logically linked to tailor the search for individual needs. The record for each unit is divided into (1) an up-to-date summary that includes rank terms, assigned ages, a detailed description of the type locality (if designated), and area of occurrence (states and geologic provinces or basins) and (2) a historical record that contains critical information abstracted from publications that have defined the unit or modified its definition. This large and growing database was developed and is maintained by the US Geological Survey in Denver, Colorado, on a supermini-class networking computer and may be accessed by other computers with 1200-baud communications capability. Output is to the screen only and on-line help files are available. You may access the database free of charge via modem for the price of your telephone call.

MacLachlan, M.E.; Bryant, W.A.; Stone, L.M.; Judkins, T.W.

1988-02-01

382

Stratigraphic hierarchy and cycle stacking, facies distribution, and Interwell-Scale heterogeneity: Grayburg Formation, New Mexico  

Microsoft Academic Search

The Grayburg Formation (middle Guadaluplan) of southeastern New Mexico is a mixed carbonate-siliciclastic succession that represents predominantly shallow water sedimentation on the Northwest Shelf of the Delaware Basin. Exceptional Grayburg outcrops in the Brokeoff Mountains permit high-resolution correlation and mapping of interwell-scale facies complexity both along depositional dip and across strike. Three orders of stratigraphic hierarchy are recognized using vertical

R. J. Barnaby; W. B. Ward

1996-01-01

383

Field and Seismic Images of Sharp-Based Shoreface Deposits: Implications for Sequence Stratigraphic Analysis  

Microsoft Academic Search

ABSTRACT: Sharp-based shoreface sandstones are of considerable in- terest because of their potential as hydrocarbon reservoirs and because they play an important role in the stratigraphic analysis of basin fills. The sharp-based shoreface sandstones studied herein are Upper Ju- rassic (Kimmeridgian?Tithonian) and exposed along the coastal cliffs of the Dover Strait in northwestern France. These series consist of tens of

J.-N. Proust; Geoffroy Mahieux; Bernadette Tessier

2001-01-01

384

CONOP9 Programs for Solving the Stratigraphic Correlation and Seriation Problems as Constrained Optimization  

Microsoft Academic Search

A ‘zipped’ version of the program CONOP9 2007 along with read-me files, sample files, and other documentation can be viewed\\u000a at the below mentioned URL link. An earlier version of CONOP9 was initially supplied with ‘High-Resolution Approaches in Stratigraphic\\u000a Paleontology’ (PJ Harries, editor) and described in Chapter 13 of that volume. This is an updated version of the program,\\u000a and

Peter M. Sadler; William G. Kemple; Marilyn A. Kooser

385

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

386

33 CFR 147.T08-849 - DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false DEEPWATER HORIZON Mobile Offshore Drilling Unit...ZONES § 147.T08-849 DEEPWATER HORIZON Mobile Offshore Drilling Unit...zone. This area surrounds the DEEPWATER HORIZON, a Mobile Offshore...

2010-07-01

387

40 CFR 112.11 - Spill Prevention, Control, and Countermeasure Plan requirements for offshore oil drilling...  

Code of Federal Regulations, 2010 CFR

...Countermeasure Plan requirements for offshore oil drilling, production, or workover facilities...Plan requirements for offshore oil drilling, production, or workover facilities...owner or operator of an offshore oil drilling, production, or workover...

2010-07-01

388

40 CFR 112.11 - Spill Prevention, Control, and Countermeasure Plan requirements for offshore oil drilling...  

Code of Federal Regulations, 2010 CFR

...Countermeasure Plan requirements for offshore oil drilling, production, or workover facilities...Plan requirements for offshore oil drilling, production, or workover facilities...owner or operator of an offshore oil drilling, production, or workover...

2009-07-01

389

33 CFR 165.1156 - Safety Zone; Offshore Marine Terminal, El Segundo, CA.  

Code of Federal Regulations, 2010 CFR

...false Safety Zone; Offshore Marine Terminal, El Segundo, CA. 165.1156...1156 Safety Zone; Offshore Marine Terminal, El Segundo, CA. (a) Location...authorized to use the offshore marine terminal for loading or...

2010-07-01

390

Stratigraphic framework and petroleum potential of northeastern Baltimore Canyon Trough, mid-Atlantic outer Continental Shelf  

SciTech Connect

Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurasic through Cenozoic rock-stratigraphic units. Most of the units are lithologically similar to formations on the Scotian Shelf and are, therefore, considered in this study to be the Scotian Shelf homotaxial equivalents. The Mohawk(.) sandstone and Mic Mac shale equivalents in the Baltimore Canyon Trough represent lower delta plain to predominantly prodelta environments, and the Abenaki-equivalent limestone represents a shelf margin carbonate buildup. Inundation by the sea was incomplete, however, and channel and distributary-mouth-bar sands (Logan Canyon equivalent) were deposited. A final marine transgression began during the Late Cretaceous and resulted in the deposition of mudstone, which is considered equivalent to the Scotian Shelf Dawson Canyon Formation. Although both basins exhibit an upward increase in sand content, the Scotian Shelf Cenozoic strata are more sandy than those in the Baltimore Canyon Trough. Stratigraphic traps may be present in the Baltimore Canyon Trough Upper Jurassic and Lower Cretaceous deltaic sandstones and shelf-margin carbonates. The deltaic units contain channel and distributary-mount-bar sandstones, which may be potential reservoirs. Seals may be formed by lateral and vertical contacts against the prodelta, interdistributary bay, and marine shales. The Abenaki stratigraphic-reef trend provides another potential target. Source rocks, reservoir rocks, and traps may be associated with the trend, but its potential can only be defined by future drilling. 16 figures, 2 tables.

Libby-French, J.

1984-01-01

391

Sequence stratigraphic setting of siliciclastic source rocks, reservoir rocks and seals  

SciTech Connect

Sequence stratigraphy is the study of stratigraphic relationships within a time-stratigraphic framework. It combines detailed analysis of sedimentary facies and depositional geometries, and defines a hierarchy of stratigraphic units that stack into progressively larger scale cycles. Each depositional cycle consists of four phases of relative accommodation change which can be related to relative water level change, such as sea level. These four phases are rising, highstand, falling, and lowstand, and the rocks deposited during each phase are called systems tracts. Each systems tract has the potential to contain organic-rich rocks, and porous and permeable reservoir rocks. However, specific depositional environments within some systems tracts are likely to have higher probability as an effective source rock, seal or reservoir. For example, regionally extensive muds are deposited during transgression and effective seals may extend over broad areas. If sedimentation rates and biologic productivity rates are optimal, some outer shelf and upper slope areas of these muds may be organic rich and could yield significant hydrocarbons upon burial into the generative window. Reservoirs also occur in predictable patterns. High-energy nearshore environments produce porous and permeable sandstones, both within lowstand and highstand prograding depositional systems. Sandstones of the highstand systems tract and the basin floor thick of the lowstand systems tract are often widely distributed and the potential for effective top-seal or lateral-seal is more problematic. For such highstand and basin floor reservoir targets structural closure is needed to form effective traps.

Armentrout, J.M. [Mobil Exploration and Production Technology Center, Dallas, TX (United States)

1995-08-01

392

Structural and tectonic setting of the Charleston, South Carolina, region: Evidence from the Tertiary stratigraphic record  

USGS Publications Warehouse

Eleven upper Eocene through Pliocene stratigraphic units occur in the subsurface of the region surrounding Charleston, South Carolina. These units contain a wealth of information concerning the long-term tectonic and structural setting of that area. These stratigraphic units have a mosaic pattern of distribution, rather than a simple layered pattern, because deposition, erosion, and tectonic warping have interacted in a complex manner through time. By generating separate structure-contour maps for the base of each stratigraphic unit, an estimate of the original basal surface of each unit can be reconstructed over wide areas. Changes in sea level over geologic time generate patterns of deposition and erosion that are geographically unique for the time of each transgression. Such patterns fail to persist when compared sequentially over time. In some areas, however, there has been persistent, repetitive net downward of upward movement over the past 34 m.y. These repetitive patterns of persistent motion are most readily attributable to tectonism. The spatial pattern of these high and low areas is complex, but it appears to correlate well with known tectonic features of the region. This correlation suggests that the tectonic setting of the Charleston region is controlled by scissors-like compression on a crustal block located between the north-trending Adams Run fault and the northwest-trending Charleston fault. Tectonism is localized in the Charleston region because it lies within a discrete hinge zone that accommodates structural movement between the Cape Fear arch and the Southeast Georgia embayment.

Weems, R. E.; Lewis, W. C.

2002-01-01

393

Examination of spaceborne imaging spectroscopy data utility for stratigraphic and lithologic mapping  

NASA Astrophysics Data System (ADS)

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.

Dadon, Alon; Ben-Dor, Eyal; Beyth, Michael; Karnieli, Arnon

2011-01-01

394

A graphical software system to present stratigraphic information of surveyed sections  

NASA Astrophysics Data System (ADS)

Stratigraphic sections are the foundation of many regional stratigraphic analyses. The Pascal program STRATCOLUMN is designed specifically as an aid to produce a graphical presentation of litho- and biostratigraphic data of a geologic section or a core. It is useful in a wide variety of geologic settings. The layout of the plot is highly flexible. In general it consists of a header, an explanation, a lithological column, and a series of adjacent columns filled with additional information. The stratigraphic layer, defined by a set of characteristics, is the fundamental element from which the lithological column is constructed. Text and data observed in the field or in the laboratory, are expressed in additional columns according to a variety of graphical layouts. Notations of lithotypes, icons of fossils, sedimentary and biogenic structures correspond as much as possible to conventional symbolism. Many are available by default in the program, but the system provides the user with ways to construct his own single or composite lithotype notations and icons. The present version of the program runs under NOS/BE operating system on a CDC CYBER mainframe. Only elementary graphic routines of CALCOMP are used, making the program adaptable to other computer environments. Free formatting throughout simplifies the structure of the input files. Large plots are produced economically, because all selected features are stored dynamically.

Sprenger, Antoinette; ten Kate, Warner G.

395

Offshore wind farm siting procedures applied offshore of Block Island, Rhode Island  

NASA Astrophysics Data System (ADS)

Since 2008, the Rhode Island Coastal Resources Management Council (CRMC) has been leading a Rhode Island Ocean Area Management Plan (RIOSAMP) in partnership with the University of Rhode Island, resulting in an extensive multidisciplinary analysis of the Rhode Island offshore environment and its suitability for siting an offshore wind farm. As part of the RIOSAMP project, a standard siting optimization approach was first developed based on a siting index defined as the ratio of costs associated with the wind farm deployment to the available wind resource. This index, combined within a marine spatial planning approach to address ecological and societal constraints, provided an initial macro-siting tool (Spaulding et al., 2010). The multiple GIS layers required in this approach and the absence of theoretical support to optimize the resulting zoning, led to an extension of the initial optimization approach into a more comprehensive macro-siting optimization tool, integrating societal and ecological constraints into the siting tool, the Wind Farm Siting Index (WIFSI) (Grilli et al, 2012). The projects led to the definition of several favorable development areas including a Renewable Energy Zone (REZ) off of Block Island, in State Waters. Deep Water Wind Inc. (DWW) plans to install and commission five 6 MW direct drive Siemens lattice jacket turbines in the REZ area, by 2014. In this thesis two major steps are accomplished to refine and expand the RIOSAMP macro-siting tool. First the macro-siting tool is expanded to include a model simulating the exclusionary zones defined by the Federal Aviation Administration (FAA) regulations. Second a micro-siting model is developed, optimizing the relative position of each turbine within a wind farm area. The micro-siting objective is to minimize, (1) the loss in power due to the loss of wind resource in the wake of the turbines (wake "effect"), and (2) the cable costs that inter-connect the turbines and connecting the farm to the land. The REZ area is chosen as test site for the algorithm, and an optimal layout for the 5 turbines is found and discussed. Similarly the FAA tool is applied to the Block Island airport demonstrating the complexity of the FAA exclusionary area, and defining the limits of the exclusionary areas. The FAA regulation model is a geometric model in which all major (FAA) regulations within RI and the RI topography are embedded. The user specifies the dimension of the proposed turbines and an airport of interest, and a map of exclusionary zones specific to the turbine height and rules applying to the airport is generated. The model is validated for the entire state of Rhode Island. The micro-siting model finds the optimum placement of each turbine for a given number of turbines within an area. It includes the aerodynamic constraints (loss in wind speed within the wake of a turbine) associated to the deployment of arrays of turbines and the cable interconnection cost. It is combined with the technical, ecological, and social constraints used in the RIOSAMP macro-siting tool to provide a comprehensive micro-siting tool. In the optimization algorithm, a simple wake model and turbine-clustering algorithm are combined with the WIFSI in an objective function; the objective function is optimized with a genetic algorithm (GA).

O'Reilly, Christopher M.

396

Sequence stratigraphic and sedimentologic significance of biogenic structures from a late Paleozoic marginal- to open-marine reservoir, Morrow Sandstone, subsurface of southwest Kansas, USA  

USGS Publications Warehouse

Integrated ichnologic, sedimentologic, and stratigraphic studies of cores and well logs from Lower Pennsylvanian oil and gas reservoirs (lower Morrow Sandstone, southwest Kansas) allow distinction between fluvio-estuarine and open marine deposits in the Gentzler and Arroyo fields. The fluvio-estuarine facies assemblage is composed of both interfluve and valley-fill deposits, encompassing a variety of depositional environments such as fluvial channel, interfluve paleosol, bay head delta, estuary bay, restricted tidal flat, intertidal channel, and estuary mouth. Deposition in a brackish-water estuarine valley is supported by the presence of a low diversity, opportunistic, impoverished marine ichnofaunal assemblage dominated by infaunal structures, representing an example of a mixed, depauperate Cruziana and Skolithos ichnofacies. Overall distribution of ichnofossils along the estuarine valley was mainly controlled by the salinity gradient, with other parameters, such as oxygenation, substrate and energy, acting at a more local scale. The lower Morrow estuarine system displays the classical tripartite division of wave-dominated estuaries (i.e. seaward-marine sand plug, fine-grained central bay, and sandy landward zone), but tidal action is also recorded. The estuarine valley displays a northwest-southeast trend, draining to the open sea in the southeast. Recognition of valley-fill sandstones in the lower Morrow has implications for reservoir characterization. While the open marine model predicts a "layer-cake" style of facies distribution as a consequence of strandline shoreline progradation, identification of valley-fill sequences points to more compartmentalized reservoirs, due to the heterogeneity created by valley incision and subsequent infill. The open-marine facies assemblage comprises upper, middle, and lower shoreface; offshore transition; offshore; and shelf deposits. In contrast to the estuarine assemblage, open marine ichnofaunas are characterized by a high diversity of biogenic structures representing the activity of a benthic fauna developed under normal salinity conditions. Trace fossil and facies analyses allow environmental subdivision of the shoreface-offshore successions and suggest deposition in a weakly storm-affected nearshore area. An onshore-offshore replacement of the Skolithos ichnofacies by the Cruziana ichnofacies is clearly displayed. The lower Morrow fluvio-estuarine valley was incised during a drop of sea level coincident with the Mississippian-Pennsylvanian transition, but was mostly filled during a subsequent transgression. The transgressive nature of the estuarine infill is further indicated by the upward replacement of depauperate brackish-water trace fossil assemblages by the open-marine Cruziana ichnofacies. Additional stratal surfaces of allostratigraphic significance identified within the estuary include the bayline surface, the tidal ravinement surface, the wave ravinement surface, and a basinwide flooding surface recording inundation of the valley interfluves. A younger sequence boundary within the lower Morrow is also recorded in the Gentzler field at the base of a forced regression shoreface, demarcated by the firmground Glossifungites ichnofacies, indicating a rapid basinward facies migration during a sea-level drop. Trace fossil models derived from the analysis of Mesozoic and Cenozoic reservoirs are generally applicable to the study of these late Paleozoic reservoirs. Pennsylvanian brackish-water facies differ ichnologically from their post-Paleozoic counterparts, however, in that they have: (1) lower trace fossil diversity, (2) lower degree of bioturbation, (3) scarcity of crustacean burrows, (4) absence of firmground suites, and (5) absence of ichnotaxa displaying specific architectures designed to protect the tracemaker from salinity fluctuations. Morrow open-marine ichnofaunas closely resemble their post-Paleozoic equivalents. ?? 2002 Elsevier Science B.V. All rights reserved.

Buatois, L. A.; Mangano, M. G.; Alissa, A.; Carr, T. R.

2002-01-01

397

Arctic and offshore research. Technology status report  

SciTech Connect

The DOE Arctic and Offshore Research (AOR) effort is designed to meet the needs for a centralized, high-quality, Arctic energy-related data base and for long-term, high-risk research. The ultimate purpose of the DOE effort is to promote extensive private use of the evolving AOR technology data base in order to accelerate development of Arctic oil and gas resources. In assessing the Arctic energy-related research needs as delineated in this report, the Morgantown Energy Technology Center (METC), with the DOE Fossil Energy Office of Oil, Gas, and Shale Technology, developed the following activities: AOR Energy-Related Technology Data Base Development; AOR Seminars and Workshops; Arctic and Offshore Energy Research Coordination; Sea Ice Research; Seafloor/Soils Research; and Subice Systems Development. The DOE AOR effort was initiated in FY 1983, the early development activities were performed in January and February 1983, and the effort evolved to its present form by the conclusion of FY 1984. The current activities have included determining the Arctic bibliographic data base and initiating most pieces of the research described above (except multiyear ice properties and pipeline research). Some of the FY 1984 major accomplishments are: four to five ice islands 1 to 2 miles in length drifting off the Ellesmere ice shelves north of Ellesmere Island were aerially surveyed. A report was completed on the location of the ice shelf edge, breakup, and regrowth of the Ellesmere ice shelves over the past two decades. Ice-ridging shear zone studies have shown that the 6- to 10-feet high shoals usually under the shear zone are not totally destroyed from ice gouging from one year to the next, but that the ice gouging may be instrumental in initiating and maintaining the shoals, which may protect Arctic offshore structures. Airborne radar sensing techniques were used to determine the electromagnetic properties of sea ice and physical properties.

Not Available

1984-10-01

398

EPA moves to control offshore emissions  

SciTech Connect

This paper reports that except for most of the Gulf Coast, the Environmental Protection Agency proposes to hold all U.S. offshore rigs and platforms within about 28 miles from shore to the same standards as onshore facilities. EPA estimated compliance will cost the oil industry $2.2 million/year for all sources on the Outer Continental Shelf. The rule, the first EPA has proposed to control air pollution from OCS operations, covers drilling and production off Alaska, the Pacific coast states, the Atlantic coast states, and the Florida Gulf Coast. It does not affect OCS areas off Texas, Louisiana, Mississippi, and Alabama.

Not Available

1991-12-09

399

Spar buoy escape system for offshore platforms  

SciTech Connect

An offshore platform is shown in position over the seabed. An escape chamber in the form of a spar buoy is mounted on a platform and extends from the platform above the surface of the water to below the surface. A cable also extends between the buoy and an anchor located on the seabed remotely from the platform. When the buoy is released from its platform mount and cable winched from the buoy, the buoy is pulled over the anchor to float safely during adverse weather conditions.

Connelly, R. F.

1985-07-09

400

Flow line riser for offshore structure  

SciTech Connect

Riser for an offshore marine platform which includes facilities to receive, treat, and/or store hydrocarbon fluid from a plurality of dispersed submerged wells. The riser includes means to accommodate a plurality of conduits between the platform deck and the floor of the body of water. As a rigid, or non-rigid conduit is pulled downwardly through the riser, it engages a deflecting shoe. The latter deflects the pulled conduit into a direction away from the platform and along the ocean floor, whereby it can readily engage a pipeline, or attach to one of the dispersed wells.

Knowles, J. P.; Mitchell, S. D.; Wheeler, S.

1985-05-28

401

Cathodic protection retrofit of an offshore pipeline  

SciTech Connect

Cathodic protection (CP) anodes and corrosion coating on two offshore pipelines were damaged during deep water installation. In-situ methods for deep-water inspection and repair of the pipelines` CP and coating systems were developed and used. High-pressure natural gas Pipeline. A design was 5.6 miles of 8.625 in. OD by 0.406 in. W.T. API SL, Grade X-42, seamless line pipe. Pipeline B design was 0.3 miles of similar specification pipe. Both pipelines were mill-coated with 14 mil of fusion-bonded epoxy (FBE) corrosion coating. Girth welds were field-coated with FBE.

Winters, R.H.; Holk, A.C. [Tenneco Energy, Houston, TX (United States)

1997-09-01

402

Glaciotectonic deformation and reinterpretation of the Worth Point stratigraphic sequence: Banks Island, NT, Canada  

NASA Astrophysics Data System (ADS)

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).

Vaughan, Jessica M.; England, John H.; Evans, David J. A.

2014-05-01

403

Sedimentological indicators of paleoenvironments and siliciclastic stratigraphic sequences in some Miocene deposits of the Calvert Cliffs, southern Maryland  

USGS Publications Warehouse

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

Shideler, G. L.

1994-01-01

404

PHYSICAL PROPERTIES OF REPRESSURIZED SAMPLES RECOVERED DURING THE 2006 NATIONAL GAS HYDRATE PROGRAM EXPEDITION OFFSHORE INDIA  

Microsoft Academic Search

As part of an international cooperative research program, the U.S. Geological Survey (USGS) and researchers from the National Gas Hydrate Program (NGHP) of India are studying the physical properties of sediment recovered during the NGHP-01 cruise conducted offshore India during 2006. Here we report on index property, acoustic velocity, and triaxial shear test results for samples recovered from the Krishna-Godavari

W. J. Winters; W. F. Waite; D. H. Mason; P. Kumar

405

The stratigraphic architecture and evolution of the Burdigalian carbonate—siliciclastic sedimentary systems of the Mut Basin, Turkey  

Microsoft Academic Search

This study describes the coeval development of the depositional environments in three areas across the Mut Basin (Southern Turkey) throughout the Late Burdigalian (early Miocene). Antecedent topography and rapid high-amplitude sea-level change are the main controlling factors on stratigraphic architecture and sediment type. Stratigraphic evidence is observed for two high-amplitude (100–150 m) sea-level cycles in the Late Burdigalian to Langhian.

P. Bassant; F. S. P. Van Buchem; A. Strasser; N. Görür

2005-01-01

406

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)

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.

Ridente, Domenico; Latino Chiocci, Francesco; Martorelli, Eleonora; Sposato, Andrea; Krastel, Sebastian; Gross, Felix; Lili, Fu; Schulten, Irena

2013-04-01

407

Hydraulics in oil drilling from offshore mobile platforms  

SciTech Connect

Because of the requirement for rapid operation of subsea safety equipment when drilling from offshore mobile platforms, special hydraulic equipment is required. This paper discusses the features of hydraulic control systems used for operation of subsea blowout preventer equipment from offshore floating drilling rigs. Special features of the hydraulic equipment are discussed along with specific requirements which influence component designs and performance evaluations.

Benson, P.R.

1982-11-01

408

Oil rigs and offshore sport fishing in Louisiana  

Microsoft Academic Search

The environmental effects of Louisiana's offshore oil platforms are discussed with regard to an increase in sport-fishing. The effects upon fish populations, species diversity, underwater habitats, and food chains from the offshore platforms are obtained from several summaries of studies undertaken between 1970-1979. (DS)

R. Dugas; V. Guillory; M. Fischer

1979-01-01

409

Oil rigs and offshore sport fishing in Louisiana  

Microsoft Academic Search

Forty years ago, offshore sport fishing in Louisiana was almost nonexistent. Offshore oil drilling platforms are the primary cause of the present increase in sport fishing in this area. Algae and other organisms forming the first step in the food chain cluster around the subsurface structures of the rigs, attracting fish that seek food and shelter. Major game species frequenting

R. Dugas; V. Guillory; M. Fischer

2009-01-01

410

Computational methods. [Calculation of dynamic loading to offshore platforms  

Microsoft Academic Search

With regard to the computational methods for hydrodynamic forces, first identification of marine hydrodynamics in offshore technology is discussed. Then general computational methods, the state of the arts and uncertainty on flow problems in offshore technology in which developed, developing and undeveloped problems are categorized and future works follow. Marine hydrodynamics consists of water surface and underwater fluid dynamics. Marine

Maeda

1993-01-01

411

Advances in offshore oil and gas pipeline technology  

SciTech Connect

This book examines the problems involved in the offshore transport of petroleum and natural gas. Topics considered include geotechnical considerations, pipeline lay-stress analysis, pipeline reeling, buckling, pipeline trenching by ploughing, the automated connection of offshore pipelines, concrete coatings, cathodic protection, spanning problems, inspection, emergency repair, safety, reliability, pressure effects, marine risers, and single point mooring systems.

delaMare, R.F.

1985-01-01

412

New Horizons for Offshore Wind Energy: Shifting Paradigms and Challenges  

Microsoft Academic Search

The placing of wind turbines offshore is likely to lead to developments of the technology as far-reaching as those which turned the crude onshore machines of the early 1980s into the elegant giants of today. This article discusses the acute need of development of offshore wind energy converting systems. The development of different design techniques and the economics of these

T. S. BHATTI; D. P. KOTHARI

2005-01-01

413

Map of Offshore Wind Energy Activity in North America  

NSDL National Science Digital Library

This map, from the North American Offshore Wind Project shows a Google map of all locations considered for having offshore wind energy. The location markers also provide information as to which projects are operational, proposed, suspended, or that have notable activity.

Project, North A.

414

International Collaboration on Offshore Wind Energy Under IEA Annex XXIII  

SciTech Connect

This paper defines the purpose of IEA Annex XXIII, the International Collaboration on Offshore Wind Energy. This international collaboration through the International Energy Agency (IEA) is an efficient forum from which to advance the technical and environmental experiences collected from existing offshore wind energy projects, as well as the research necessary to advance future technology for deep-water wind energy technology.

Musial, W.; Butterfield, S.; Lemming, J.

2005-11-01

415

Lost in migration: offshore need not mean outsourced  

Microsoft Academic Search

Too often large corporations assume that migrating operations offshore requires outsourcing them to another company. Global outsourcing is not always a better alternative to going it alone offshore or teaming up with a partner overseas. On the contrary, companies that set up their own operations in low-cost regions increasingly generate returns comparable to or higher than companies that outsource. What’s

Simeon Preston

2004-01-01

416

CHEMICAL COMPOSITION OF PRODUCED WATER AT SOME OFFSHORE OIL PLATFORMS  

EPA Science Inventory

The effectiveness of produced water treatment was briefly studied in offshore oil and gas extraction operations in Cook Inlet, Alaska, and the Gulf of Mexico. Three offshore oil extraction facilities were examined in the Cook Inlet production field, and seven platforms were studi...

417

Organisational factors, safety attitudes and workload among offshore oil personnel  

Microsoft Academic Search

The aim of this article is to show how job stress, physical working conditions, commitment and involvement in safety work, and attitudes towards safety and accident prevention work among employees on offshore petroleum platforms have changed from 1990 to 1994. In 1990 a self-completion questionnaire survey was carried out among personnel on offshore oil installations in the Norwegian part of

T Rundmo; H Hestad; P Ulleberg

1998-01-01

418

Conventional Generation for Balancing 6 GW Offshore Wind Power  

Microsoft Academic Search

The Dutch government has set the objective of 6 GW installed offshore wind power capacity by 2020. Due to the variability and unpredictability of wind power production, this amount of offshore wind power can be foreseen to have large consequences for power system balancing in the Netherlands. Notably, Dutch wind power is subject to program responsibility like any other energy

B. C. Ummels; M. Gibescu; W. L. Kling; G. C. Paap

419

Offshore Oil: Environmental Impacts on Land and Sea  

ERIC Educational Resources Information Center

Presents a counter position to that provided in SE 512 127 in which the author emphasizes that there are too many problems yet to be solved (related to offshore oil development) to proceed with full-scale development of offshore oil drilling. (PEB)

Baldwin, Pamela L.

1974-01-01

420

Using semantics to facilitate data integration of offshore wind farms  

Microsoft Academic Search

Operation and maintenance play an important role in extracting power from the wind, especially, in offshore wind energy where wind farms are located far off the shore and under harsh weather conditions. Improved operation and maintenance is likely to reduce costs as well as hazard exposure of the employees. Implementation of advanced information technology is thus crucial for operating offshore

Trinh Hoang Nguyen; Andreas Prinz