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High-resolution sequence stratigraphy concepts are applied to Erema, a Miocene onshore field of the Niger delta. The field's production is decreasing and an up-to-date geological model is essential to monitor the production. We aim to show an approach, using subsurface data and sequence stratigraphic concepts, which results in a time-line (Maximum Flooding Surfaces) correlation scheme. This scheme is based upon a facies model and is destined to guide the study of the characterization of reservoir heterogeneities. Using the cored well as a reference point, the facies model consists of shoreface dunes (planar tabular cross-stratified sandstones) changing landward into fluvial distributary deposits (through cross-stratified sandstones) via a tide-influenced coastal plain facies. The stacking pattern of genetic units shows a seaward stepping phase at the reservoir scale (sixty ...

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An outcrop-based study combining detailed lithofacies analysis with high-resolution sequence stratigraphy in the Paradox Basin, southwestern United States. has shown that complex lateral and vertical facies variations occur in relatively consistent and predictable patterns. Large-scale facies shifts of several kilometers occur across major sequence boundaries whereas small-scale lateral and vertical variations develop from stacking of individual cycles. Understanding of vertical stacking patterns and lateral distribution of facies in outcrop can be directly applied to both three-dimensional distribution of reservoir facies in the subsurface as well as the evaluation of heterogeneity within individual reservoirs. The Desert Creek and Ismay intervals of the Paradox Formation (Pennsylvanian) exposed along the San Juan River in southeastern Utah are characterized by high-frequency cyclic repetition of ...

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This thesis studied the petrology and sequence stratigraphy of the Hoadley barrier, a Glauconitic member in the Westerose field in Alberta. The unit contains gas reserves in an extensive northeast-southwest trending marine complex. A high resolution sequence stratigraphic model was used to understand the facies development of the unit and the diagenetic pathway of the strata. Six high frequency sequences were identified within the Glauconitic member. Each are separated from one another by surfaces of incision or subaerial exposure which sometimes coincide with a flooding surface and erosion. This thesis provided a petrographic characterization and depositional history of each of the 6 sequences. Reservoir quality is developed within the relatively quartz-rich foreshore facies of the G2B sandstones. The G3 chert litharenite to sublitharenite sandstones are excellent gas producers because of their coarser ...

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The thesis deals with methods of describing the reservoir rock in central oil and gas fields on the Norwegian continental shelf. Methods of enhancing the level of recovery are dealt with. Following topics are given: Sand body dimensions and infill sequences of stable, humid-climate delta plain channels; minipermeameter-based study of permeability trends in channel sand bodies; significance of tidal cyclicity for modelling of reservoir heterogeneities in the lower Jurassic Tilje Formation, mid-Norwegian shelf; geometry and facies of large-scale flow units in fluvial-dominated fan-delta-front sequences; quantified fluvial architecture in ephemeral stream deposits of the Esplugafreda Formation (Palaeocene), Tremp-Graus Basin, northern Spain; the Safari project - collection and storage of field analogue data for quantitative reservoir modelling; sedimentary architecture of field analogues for reservoir information (SAFARI): a case study of the fluvial Escanilla ...

British Library Electronic Table of Contents (United Kingdom)

The Alpine Foreland Basin is a minor oil and moderate gas province in central Europe. In the Austrian part of the Alpine Foreland Basin, oil and minor thermal gas are thought to be predominantly sourced from Lower Oligocene horizons (Schoneck and Eggerding formations). The source rocks are immature where the oil fields are located and enter the oil window at ca. 4 km depth beneath the Alpine nappes indicating long-distance lateral migration. Most important reservoirs are Upper Cretaceous and Eocene basal sandstones.Stable carbon isotope and biomarker ratios of oils from different reservoirs indicate compositional trends in W-E direction which reflect differences in source, depositional environment (facies), and maturity of potential source rocks. Thermal maturity parameters from oils of di...

British Library Electronic Table of Contents (United Kingdom)

The Yaojia Formation recovered by CCSD-SK-Is borehole (China Cretaceous Continental Scientific Drilling-SongkeI-the south borehole) is 157.67 m long and 99.96% of cores recovery. The age of the formation corresponds with a range from the Santonian to the early Campanian. The sequences and processes of lithology-lithofacies and cyclic stratigraphy are revealed by a detailed core description. Eleven rock types and three kinds of sedimentary subfacies, including shallow lake, deep lake, and delta front, are recognized from the drilling core. There are eleven sedimentary microfacies including dolostone, argillaceous limestone, shallow lake turbidite, deep lake turbidite, subaqueous mouth bar, distal bar, sheet sandstone, subaqueous distributary bay, slump deposits, shallow lake mudstone, and d...

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The Lower Cretaceous Falher Member (Spirit River Formation) in the Deep Basin of Alberta is composed of 5 units (A-E) comprising the reservoir of the giant Elmworth gas field. Using high resolution sequence stratigraphy, 333 well logs and 65 cores were integrated to understand the evolution of Falher C and D in the study area. Five major faces associations were defined in each unit. The basal surface of Falher D overlies nonmarine deposits (Falher E) and is defined by a marine flooding surface (transgressive surface of erosion) partially modified by a subsequent regressive surface of erosion. Southward, all the facies become more continental and the marine flooding surface passes into a lagoon-on-nonmarine contact. Falher D contains a series of shingled marine sandstone lenses separated by erosional surfaces interpreted as seaward-dipping ravinement surfaces indicating different phases of marine transgression-regression. The Falher C basal ...

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The detailed sequence stratigraphic analysis of the siliciclastic-dominated Late Cretaceous sediments (Aren Sandstone and Garumnian red beds, south central Pyrenees, Spain) reveals the repeating disposition of critical elements and controlling mechanisms of cycles and sequences. Our approach integrates (a) hierarchy of unconformity-bounded units, (b) physical expression of boundaries traceable from the continent to the basin, (c) featuring facies and depositional systems, (d) well log and seismic expression, and (e) driving basing-filling mechanisms. A comparison to other active basins is suggested in order to prove the validity beyond the regional scale. Four basin-wide transgressive facies cycles were identified and interpreted as third-order units. The transgressive phase of each cycle is represented by mixed shelf deposits, while regressive periods consists of complex delta systems. The cycles are composed within their ...

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Utah oil fields have produced over 1.2 billion barrels (191 million m{sup 3}). However, the 13.7 million barrels (2.2 million m{sup 3}) of production in 2002 was the lowest level in over 40 years and continued the steady decline that began in the mid-1980s. The Utah Geological Survey believes this trend can be reversed by providing play portfolios for the major oil-producing provinces (Paradox Basin, Uinta Basin, and thrust belt) in Utah and adjacent areas in Colorado and Wyoming. Oil plays are geographic areas with petroleum potential caused by favorable combinations of source rock, migration paths, reservoir rock characteristics, and other factors. The play portfolios will include: descriptions and maps of the major oil plays by reservoir; production and reservoir data; case-study field evaluations; summaries of the state-of-the-art drilling, completion, and secondary/tertiary techniques for each play; locations of major oil pipelines; descriptions of reservoir outcrop analogs; and ...

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The main objective of this dissertation is to build a numerical 3D geological model of a turbidite reservoir using well and seismic data. For the, the first step was to elaborate a depositional model using a high-resolution genetic stratigraphy approach. Simultaneously, the stratigraphic inversion over the seismic data resulted in an optimal acoustic impedance model. Both models, were used to build, by geostatistical methods, a 3-D geological model, which represents the spatial distribution of the reservoir facies. The studied case is the late Cretaceous Namorado turbidite system in the Campos basin, which is the reservoir of the Namorado oil field, located 80 km from the Brazilian coast, under a bathymetry between 110 and 250 m. The reservoir is a turbidite succession with 90 to 180 m thickness. It is composed by sand-supported conglomerates, matrix-supported conglomerate, massive sandstones, shales, marls and limestones. Four lithotypes ...

Science.gov (United States)

... on a transgressive surface; examples from the Silurian Whirlpool Sandstone of southern Ontario, Canada. Journal of Sedimentary ... and C. J. Salas. 1991. The Lower Silurian Whirlpool Sandstone. in Cheel, ...

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An additional 450 wells were added to the structural database; there are now 2550 wells in the database with corrected tops on the Juana Lopez, base of the Bridge Creek Limestone, and datum. This completes the structural data base compilation. Fifteen oil and five gas fields from the Mancos-ElVado interval were evaluated with respect to the newly defined sequence stratigraphic model for this interval. The five gas fields are located away from the structural margins of the deep part of the San Juan Basin. All the fields have characteristics of basin-centered gas and can be considered as continuous gas accumulations as recently defined by the U.S. Geological Survey. Oil production occurs in thinly interbedded sandstone and shale or in discrete sandstone bodies. Production is both from transgressive and regressive strata as redefined in this study. Oil production is both stratigraphically and structurally controlled with production occurring along ...

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Recent work on the St. Louis Limestone in southwestern Kansas has demonstrated that these units contain a significant eolian facies component (up to 80-90% of total unit thickness). Reservoir intervals within the St. Louis are confined to relatively thin subtidal grainstones that, in turn, are capped by a muddy carbonate and shale facies. Critical to exploration and development of these grain-shoal reservoirs is an understanding of their spatial and stratigraphic distribution. Core through the St. Louis and St. Genevieve limestones has been examined and features have been recognized at the top of the eolianites. These surfaces are interpreted as long-term exposure surfaces. The contact between the subtidal grainstone shoals and the overlying muddy carbonate and shale facies is relatively sharp and is interpreted as representing a flooding surface separating shoal from muddy-open shelf facies. In the St. ...

Science.gov (United States)

Approximately 1.2 million kg of uranium oxide (yellow cake) has been produced from the area surrounding Gunnison, Colorado. Over 99 percent of this has come form the Cochetopa and Marshall Pass districts. Uranium in both districts and many of the other occurrences is associated closely with fault and shear zones which cut brittle host formations (sandstones and dolomites) of Paleozonic and Mesozoic age. Minor uranium occurrences are in pegmatites and shear zones in Precambrian rocks, Cambrian vein material, and sandstones of Tertiary age. In the paper presented, the uranium occurences are described by districts. In addition, possibilities for additional discoveries are discussed. (JMT)

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In the early 1980s, a program was begun to evaluate the oil shale resources of the Albert Formation by undertaking a geological lithofacies study of the Albert strata in the Moncton Subbasin of southeastern New Brunswick. Most rock exposures of the Albert were examined from 1982-84 and additional field work was carried out in the summers of 1989 and 1990. In January 1989, 1,900 km of Vibroseis seismic reflection profiles shot from 1981-84 by Chevron Canada Resources Ltd. in the Moncton and Sackville subbasins became publicly available. This report gives the results of the geological investigations on the Albert Formation in the southeastern Moncton Subbasin and the integration of interpreted seismic reflection profiles to help resolve some of the geological problems encountered.

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An atlas series about the offshore northern Gulf of Mexico will group gas and oil reservoirs into subregional plays and will display reservoir data on a computerized geographical information system. The atlas series will provide critically compiled reservoir engineering data to help the private sector explore and develop hydrocarbons and to help the public sector analyze the hydrocarbon endowment in this basin. In this report, we cover aspects of the play-analysis procedure and provide specific examples of lower Miocene plays from the upper Texas coast and Federal Outer Continental Shelf (OCS). Play analysis emphasizes using broad classes of structural style, depositional style and environments, and defining attributes to group reservoirs into plays. To date, we have identified 4 Oligocene and 25 Miocene plays in Texas State offshore waters and 115 plays in the Federal OCS. Texas State offshore plays are gas prone (cumulative production 3.7 TcF) and are preferentially trapped in ...

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Olive field is oil productive from a thin stratigraphically trapped sandstone within the Upper Cretaceous lower Tuscaloosa Formation. The discovery of Olive in 1981 led to renewed interest in the Mid-Dip Tuscaloosa Trend that continues today. Discovery and development was based on the correlation of the B sandstone to a mappable soft seismic event at a depth of 10,500 ft. The field was developed by 25 wells on 40-acre spacing. Olive has been waterflooded since 1983 and is a target for enhanced recovery using carbon dioxide. A total of 7.5 million stock tank bbl or approximately 75% of the original oil in place is estimated to be recoverable by conventional and enhanced recovery methods. The B sandstone was deposited by a northwest to southeast-flowing high-sinuosity meandering river system. Point bar, channel, and channel abandonment deposits are present. The point bar formed from the lateral migration of the river system ...

British Library Electronic Table of Contents (United Kingdom)

The construction suitability of a dimension stone depends on its weathering properties along with the petrology and the petrophysical properties. The aim of this study was to evaluate the suitability of the dimension stones from the ?Drei Gleichen? area for construction and replacement purposes. In total, six sandstones (Ingersleben, Wachsenburg, Hindfelden, Seeberg, R?hnberg, Gleichenberg; Upper Triassic) as well as two carbonates (Wachsenburg sinter; Quaternary, Wandersleben dolomite; Middle Triassic) were analysed. The results from our laboratory and on-site studies of the dimension stones show that rocks from the same stratigraphic layer, like the sandstones from the upper Triassic, can show major differences in their petrophysical and weathering properties. These differences are attri...

British Library Electronic Table of Contents (United Kingdom)

A series of branched alkylbenzene ranging from C15 to C19 with several isomers (2?5) at each carbon number were identified in sediments from the Dongsheng sedimentary uranium ore deposits, Ordos Basin, China. The distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts. The branched alkylbenzenes from organic-rich argillites and coals range from C15 to C19 homologues, in which the C17 or C18 dominated. On the other hand, the C19 branched alkylbenzenes dominated in the sandstone/siltstone extracts. The obvious differences of the branched alkylbenzene distributions between the uranium-host sandstones/siltstones and the interbedded barren organic-rich mudstones/coals probably indicate their potential use as biological markers associated with part...

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The stratigraphic bore GSQ Ipswich 26 was drilled by the Department of Mines southeast of Ipswich in 1981. Late Triassic sedimentary rocks of the Moreton and Ipswich Basins were encountered above 919.9 m depth. Below this depth acid to intermediate volcanic rocks and minor amounts of interbedded volcanogenic sediments were intersected, also probably of Late Trassic age. The bore reached a total depth of 1238.8 m in volcanogenic conglomerates and sandstones.

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Sequence stratigraphic interpretation of paralic successions is complicated by the complex interfingering of marine and continental strata. The successions may also include terrestrial extensions of marine parasequences and completely independent lacustrine parasequence analogues. Failure in recognizing the possible interbedding of these two independent parasequence types may lead to construction of sequence stratigraphic schemes based on incompatible data sets. We have studied a Lower Jurassic paralic section from the Baltic island of Bornholm. The Hettangian-Sinemurian Sose Bugt Member (Ronne Formation) of Bornholm includes lacustrine, fluvial and restricted marine, estuarine deposits reflecting the basin-margin position. Biostatigraphic resolution is poor and a sequence stratigraphic interpretation of the paralic succession is far from straightforward. A multidisciplinary approach including facies analysis, recognition and lateral tracting of key surface, ...

International Nuclear Information System (INIS)

The ore-hosting Yaojia Formation is composed of a set of braided stream medium-fine grained sediments. Guided by the basic theory of high-resolution sequence stratigraphy, and based on the core observation, the analysis of chemical composition of rocks, and data of natural potential logging and apparent resistivity logging, the authors have set up the high-resolution sequence stratigraphy framework of the ore-hosting Yaojia Formation, and discussed the relation of the stratigraphic structure of the middle cycle, as well as the paleotopography, the micro-facies to the formation of uranium deposit. (authors)

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The paleogeography postulated from the distribution of Permian and Triassic sedimentary rocks in the Middle East is shown and related to the paleostructure of the region. The Middle East region as defined here includes the Arabian Peninsula, Iran, Iraq, SE Turkey, Syria, Lebanon, Jordan, West Jordan, and the Sinai Peninsula. Within the limits of the area included in this study, a relatively stable pre-Late Triassic tectonic regime can be recognized and distinguished from a succession of diastrophic events of the Late Triassic epoch, which caused marked changes in the types and distribution of facies. Excluding NE Iran, the Middle East was stable from Late Cambrian to Middle Triassic times, as it formed a part of the Arabian Massif and much of the Middle East Platform, which is a broad shelf bordering the positive Afro-Arabian Massif to the NE and east. The sediments of this platform have undergone no strong deformation and have been subjected only to epeirogenic ...

International Nuclear Information System (INIS)

Most of the petroleum fields in the Norwegian sector of the North Sea are sandstone reservoirs; the oil and gas are trapped in different species of sandstone. But the Ekofisk Field is a chalk reservoir, which really challenges the operator companies. When oil is produced from chalk reservoirs, water usually gets in and the reservoir subsides. The subsidence may be expensive for the oil companies or be used to advantage by increasing the recovery rate. Since 60 per cent of the world's petroleum reserves are located in carbonate reservoirs, it is important to understand what happens as oil and gas are pumped out. Comprehensive studies at the Department of Petroleum Technology and Applied Geophysics at Stavanger University College in Norway show that the mechanical properties of chalk are considerably altered when the pores in the rock become saturated with oil/gas or water under different stress conditions. The processes are extremely complex. ...

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The geology and resources of the lower Yellow Creek area, an area at the northwestern margin of the Piceance Creek basin comprising of four 7.5-minute quadrangles, are described. Subsurface face rocks penetrated by drill holes range in age from Pennsylvania to Cretaceous. Measured sections show the Mancos Shale and the Castlegate Sandstone, Iles Formation, and Williams Fork Formation of the Mesaverde Group of Late Cretaceous age and the Fort Union, Wasatch, Green River, and Uinta formations of Tertiary age. Surficial deposits of Quaternary age include terrace gravels, alluvium, and landslides. Fold axes and faults in the area trend northwesterly. The southern part of the area contains major oil-shale resources. Coal-bearing zones in the Williams Fork and Iles formations contain considerable coal. The coal-resources potential is limited, however, by nonpersistence of the thicker coal beds. Small amounts of gas have been produced from shallow, lenticular Tertiary ...

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A petrographic comparison of Triassic, fluvial sandstones from the Deep River Basin in the eastern piedmont of North Carolina with nearby Holocene stream sands (1) indicates that he Triassic climate was more arid than today's and (2) distinguishes an eastern, more plutonic terrane from a western, more metamorphic source terrane. The paleoclimatic interpretation is based on differences in framework composition between modern and ancient sands of the same grain size, derived from the same rock type, transported similar distances and deposited in similar settings. The Triassic sandstones contain more lithic-fragments but less quartz than otherwise equivalent, modern sand in the Deep River Basin. Feldspar content is more complex, controlled by both source-rock composition and climate. Sand from the more plutonic terrane contains more feldspar and plutonic lithic-fragments than sand from the more metamorphic terrane, which contains more ...

International Nuclear Information System (INIS)

Larsen syndrome is an autosomal-dominant disorder characterized by multiple joint dislocations, vertebral anomalies and dysmorphic facies. Both autosomal-dominant and autosomal-recessive forms of the disorder have been proposed. Individuals with autosomal-dominant Larsen syndrome have characteristic ''cylindrical-shape'' thumbs caused by broad, shortened phalanges. Autosomal-dominant Larsen syndrome results from heterozygosity for mutations in filamin B, a cytoskeletal protein involved in multicellular processes. We report here a patient with a duplicated or accessory distal thumb phalanx and multiple large joint dislocations who was shown to be heterozygous for a filamin B mutation predicting the amino acid substitution G1691S. This adds a new radiographic finding, duplicated or accessory distal phalanx, to the radiographic abnormalities seen in this rare dominant disorder. (orig.)

British Library Electronic Table of Contents (United Kingdom)

The southern Alaska convergent margin contains several small belts of sedimentary and volcanic rocks metamorphosed to blueschist facies, located along the Border Ranges fault on the contact between the Wrangellia and Chugach terranes. These belts are significant in that they are the most inboard, and thus probably contain the oldest record of Triassic-Jurassic northward-directed subduction beneath Wrangellia. The Liberty Creek HP-LT schist belt is the oldest and the innermost section of the Chugach terrane. Within this belt lawsonite blueschists contains an initial high-pressure assemblage formed by lawsonite+phengite+chlorite+sphene+albite+/-apatite+/-carbonates and quartz. Epidote blueschists are composed of sodic, sodic-calcic and calcic amphiboles+epidote+phengite+chlorite+albite+sphen...

British Library Electronic Table of Contents (United Kingdom)

The first member of the Qingshankou Formation recovered by CCSD-SK-Is borehole (China Cretaceous Continental Scientific Drilling-SongkeI-the south borehole) is 81.41 m long, and the recovery of cores is 100%. The age of the member is approximately Turonian. The sequence and process of lithology-lithofacies and cyclic stratigraphy were revealed by a detailed core description. 6 rock types (mudstone, dolomite, marl, limestone, ostracode limestone, and volcanic ash) comprise the sedimentary strata. Deposition occurred in a deep lake, including 6 sedimentary microfacies: mudstone, sandy turbidite, dolomite, marl, limestone, and volcanic ash microfacies. The first member of the Qingshankou Formation represents 81 meter-scale cycles (sixth-order cycle), 25 fifth-order cycles, 6 fourth-order cycl...

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The Pequop Mountains (PM), Wood Hills (WH) and East Humboldt Range (EHR), NE Nevada, provide evidence that the hinterland of the Sevier thrust belt experienced large-magnitude Mesozoic shortening ([>=]55 km) and crustal thickening ([>=] 30 km). These ranges expose a structurally continuous crustal cross section of unmetamorphosed to high pressure upper amphibolite facies Triassic to Precambrian miogeoclinal strata. This sequence lies structurally beneath unmetamorphosed extensional klippen that omit metamorphic grade and crustal section, but also repeat stratigraphic units. Because they repeat stratigraphic units, the underlying miogeoclinal section, or footwall, must have once lain beneath a thrust fault (herein named the Windermere thrust). The footwall of the Windermere thrust was exhumed by two generations of top-to-the-W-NW low-angle normal faults that are distinguished by whether they are depositionally overlapped by Eocene volcanic rocks or if they cut ...

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The poster illustrates how the recent developments in genetic stratigraphy have contributed to constrain reservoir layering and to improve prediction of reservoir quality in the oil-bearing reservoir of N`KOSSA. The mixed lithology deposits formed during Albian times. Thanks to the excellent core coverage of the reservoir (4 cored wells over the entire reservoir interval), continuous sedimentological examination and interpretation of the facies succession have been carried out. The reservoir can be subdivided into composite sequences (50 to 150 in thick) which are made up of stacked metre-scale genetic units. Three different stacking patterns of genetic units have been identified; retrogradation, aggradation and progradation. These patterns reflect a gradual change of depositional regimes through time. Facies variations (texture, bio-association, geometry, spatial distribution) and early diagenetic overprints can be related to each type of ...

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The Buntsandstein facies outcrops along a 12 km long, 150 m thick cuesta near Ayllon (Central Spain). The outcrop study is based on vertical sedimentological sections and continuous photo paneling, and demonstrates the presence of two depositional systems: an alluvial fan system in the lower half of the outcrop, and a straight and braided river system in the upper part of the outcrop. This overall evolution is probably related to base-level fall to base-level rise cycle, in which the reservoir architecture is linked to genetic units stacking pattern: during the base-level fall, the alluvial fan is prograding over sand flat and sandy alluvial plain deposits. Coarse and pebbly proximal sandsheets are interbedded with finer reddish distal deposits. Reservoirs units are laterally continuous, but silty alluvial plain deposits constitute vertical permeability barriers, during base-level stillstand, erosive channels and sandsheets are vertically amalgamated. Reservoirs ...

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Lacustrine rocks are a significant component of many rift-valley sequences. Comparisons of both active and ancient rift valleys indicate that the lacustrine facies are commonly rich in organic matter and may be important sources for oil. For example, Holocene sediments in Lake Tanganyika and Cretaceous lacustrine rocks in west Africa contain as much as 12% and 20% TOC, respectively. The Newark Supergroup contains abundant lacustrine rocks. The widespread occurrence of black shales, the general similarity to known organically rich rift systems, and a few isolated geochemical analyses have caused some speculation about the potential of the Newark Supergroup to be an effective source of oil and gas. Sufficient geochemical analyses are available from lacustrine rocks in the Newark, Connecticut, and Deep River basins to evaluate their potential as hydrocarbon sources. In general, both the quantity and quality of organic matter in these rocks are less than that required ...

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Cretaceous Sunniland Formation rudistid reservoir facies buried at 3,520 meters (92 C) between evaporite units contain marginally mature algal sapropelic carbonate source rock hydrocarbons. The closed system aids in identification of porosity redistribution related to hydrocarbon emplacement. Multiple dissolution and cementation events associated with hydrocarbon migration pulses are particularly evident along stylolites. Corrosion usually predates typically interparticle first generation saddle dolomite, and corroded saddle dolomite may be observed with two generations of optically continuous limpid overgrowths separated by a corrosive boundary. Dissolution or dedolomitization may provide a magnesium source for subsequent dolomite cements. Carbonic and organic acids are probable primary corrosive agents. Moldic, stylolite and fracture porosity, often reduced by dolomite cements, was generated. Moldic pores may develop from peloids by dissolution of peripheral ...

British Library Electronic Table of Contents (United Kingdom)

Nineteen fungal strains having an ability to oxidize elemental sulfur in mineral salts medium were isolated from deteriorated sandstones of Angkor monuments. These fungi formed clearing zone on agar medium supplemented with powder sulfur due to the dissolution of sulfur. Representative of the isolates, strain THIF01, was identified as Fusarium solani on the basis of morphological characteristics and phylogenetic analyses. PCR amplification targeting 16S rRNA gene and analyses of full 16S rRNA gene sequence indicated strain THIF01 harbors an endobacterium Bradyrhizobium sp.; however, involvement of the bacterium in the sulfur oxidation is still unclear. Strain THIF01 oxidized elemental sulfur to thiosulfate and then sulfate. Germination of the spores of strain THIF01 was observed in a liqui...

International Nuclear Information System (INIS)

This report summarizes the results of a research programme which involves the development of a laboratory experimental facility for the simulation and study of hydro-thermo-mechanical processes in saturated geomaterials with low permeability. The experimentation involves a synthetic cement based porous material made of cement grout which possesses permeabilities in the range of dense unfractured sandstones or shale. Specially manufactured pore-pressure transducers were installed within the cylindrical block at locations adjacent to a plane free boundary. The block was saturated with the periodic application of a vacuum. In its saturated state the plane boundary of the block was subjected to heating via a circular heater the temperature of which was maintained constant. The resulting pore pressure generation along with temperature at these locations was monitored continuously. The results of a series of experiments are documented and further extensions to the ...

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The sedimentary geometry is determined by several types of stratigraphic surfaces: transgressive surfaces (TS), maximum flooding surfaces (MFS) and downward shift surfaces (DS). They are organized hierarchically into major and minor surfaces from the facies stacking-pattern. These surfaces which are observable on well logs and cores structure the sedimentary architecture and are, therefore, the best candidates to form major seismic reflectors. The well (logs and cores) to seismic (surface seismic) passage involves inherently a change of observation scale. That is from a high resolution sequence stratigraphy (metric to pluri-metric) to a sequence stratigraphy s.l. (decametric to pluri-decametric). This passage is composed of two phases. The first phase consists of the validation of density and sonic logs whose product corresponds to the acoustic impedance. The second phase allows for the modelling of the geological cross section of a field in a synthetic seismic ...

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Two phases are recognized in the maturation of organic matter and evolution of the oil-generative window (OGW): (a) a basinal subsidence phase during which potential source rocks undergo burial through a static initial OGW, and maturation is due essentially to increasing temperature with depth, and (b) a postsubsidence phase during which the OGW moves vertically upward through the static sedimentary fill, and maturation is due to time effects. Only the final shallow position of OGW can be defined by geochemical indices of maturity. The hydrocarbon generation sequence progresses from bottom to top, beginning with the lighter hydrocarbons (or even thermogenic gas) at the initial OGW at depth, followed by progressively heavier hydrocarbons as the OGW moves vertically upward. This dynamic model of hydrocarbon generation permits modeling of past positions of OGW relative to basin evolution through interpretation of oil-genesis nomographs. It also provides genetic explanation for the ...

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The Permian San Andres Formation of late Leonardian-early Guadalupian age is a significant hydrocarbon producer and crops out over a large area in south-central New Mexico. However, since its definition in 1909, the age and depositional environment of this unit have been questioned. In 1971 in Pecos County, Vincent Kelly divided the unit into three members: Rio Bonito, Bonney Canyon, and Fourmile Draw. The lowest member, although named for the Rio Bonito, has a type section designated at Sunset along U.S. Highway 70/380. Two miles east of Sunset, near Riverside, on the Rio Bonito, the Rio Bonito Member is exposed in a long series of roadcuts. Petrographic investigation of these rocks reveals an alternating sequence of high to low-energy intertidal to subtidal facies marked by oolitic and fossiliferous dolocalcarenite interbedded with dolomitic mudstone. The unit has been recrystallized and stylolites are abundant, as is dolomite and nodular mosaic anhydrite. These ...

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The deep water parts of the Moere and Southern Voering Basins are large frontier areas, which are considered to contain significant undiscovered hydrocarbon resources, within Cretaceous and Paleogene reservoirs. PGS Reservoir AS have evaluated the Cretaceous and Paleogene successions of the shallow and deep water areas offshore Mid-Norway using high-resolution sequence stratigraphic techniques. The successions have been subdivided into about 20 stratigraphic sequences. The results are: (1) A more acurate and higher resolution stratigraphy, (2) Greater constraints on basin palaeoenvironmental and palaeogeographic reconstructions, (4) Fully integrated sandstone fairway models, with increased ability to reservoir and seal quality and continuity, (5) In addition to several obvious giant domal traps, subtler yet significant structural and stratigraphic leads and prospects can be identified, (6) The timing, volume and phase of hydrocarbon generation may be estimated more ...

International Nuclear Information System (INIS)

A nation-wide survey of natural radioactivity in building materials was conducted during 1982-1984. Samples including industrial wastes, by-products and common building materials were collected from main building material manufactories in 29 provinces except Taiwan. The results of exposure rates, specific activities and release rate for "2"2"2Rn are presented. The specific activities of common materials are listed in declining order as follows: clay bricks > common concrete and sandstones > limes and ordinary cement. The highest level was found in breeze bricks made of stone coal, phosphogypsum and red mud with high intrinsic radioactivity. Therefore, these raw materials should be strictly controlled in manufacturing building materials. The measurement results also showed that the typical specific activities of common building materials in our country were "2"2"6Ra 50 Bq/kg, "2"3"2Th 50 Bq/kg and "4"0K 500 Bq/kg. Based on the surveyed results and foreign ...

International Nuclear Information System (INIS)

The Lander Quadrangle, Wyoming, was evaluated to a depth of 1500 m to identify environments and delineate areas that exhibit characteristics favorable for the the occurrence of uranium deposits. The evaluation used criteria established for the National Uranium Resources Evaluation program. The methods of surface investigations included evaluation of aerial radiometric and hydrogeochemical stream-sediment reconnaissance data, verification of some reported uranium occurrences, and general field geology with rock, water, and sediment sampling. The subsurface evaluation was accomplished through the use of 230 various oil-well logs. The results of this investigation identified three environments favorable for sandstone uranium deposits in Eocene fluvial sediments. These environments are within the Battle Spring and upper Fort Union Formations of the northern Great Divide Basin and within the Wind River and the Wagon Bed Formations of the southwest Wind River Basin. ...

Energy Technology Data Exchange (ETDEWEB)

We have developed an ion probe technique for the in situ measurement of oxygen isotope ratios, {sup 18}O/{sup 16}O and {sup 17}O/{sup 16}O, with high spatial resolution in polished thin sections of silicate minerals. This technique allows the isotopic analysis of samples as small as picomoles of material which represents only 10{sup -7} of the sample size required by conventional fluorination oxygen isotope measurement methods and thus has wide application to the study of many terrestrial and extra-terrestrial samples that have heterogeneous oxygen isotope compositions on a scale of tens of micrometres. To illustrate the breadth of studies that are made possible by the ion probe, we report here oxygen isotope measurements from an authigenic quartz overgrowth obtained from the Penrith sandstone, UK, and measurements of magnetite grains from the Orgueil and Yamato 82162 carbonaceous chondrites which may be used to constrain possible formation mechanisms of the ...

Energy Technology Data Exchange (ETDEWEB)

The primary purpose of the pilot Coal Compilation Project is to provide coal resource maps to stimulate and support industry exploration programs and to assist government in matters of resource management. An essential feature of the program is the use of cost effective Geoscience Information System (GSIS) technology that allows the database and various thematic maps to be analysed, updated and displayed with complete flexibility at any scale. This report describes the main features (geology, resource management, exploration history, coal occurrences etc.) of the study area, mapsheet NTS 83E/9 (Moberly Creek), and includes a copy of the 1:50,000 scale map produced. The study area is located in West-central Alberta and contains coal measures deposited amid thick successions of sandstones, siltstones, shales and conglomerates. These coal-bearing sequences are part of the Luscar Group, Upper Cretaceous Brazeau Formation and Paleocene Coalspur Formations. Coal seams ...

Energy Technology Data Exchange (ETDEWEB)

The Ordos Basin is a typical lapped basin, including three sequences of strata: early Paleozoic, late Paleozoic and Mesozoic, with a total thickness of 4000-6000m. Impermeable sealing beds are well developed at the top and base of the upper Paleozoic sequence, separating it from the Mesozoic and the lower Paleozoic strata to form an independent petroleum system. In this petroleum system, the source rocks are widely distributed coals and dark mudstones occurring in the Carboniferous-lower Permian coal measures, with a thickness of 10-15 and 40-60m, respectively. The reservoirs are mainly early Permian tight sandstones, mostly with a porosity of 4-8% and a permeability of 0.1-1.0x10{sup -3}{mu}m{sup 2}. The regional cap rock is a 100-150m thick mudstone in the upper Permian strata. The structural framework of the basin is a huge asymmetric syncline, dipping gently toward the east and north, and steeply toward the south and west. Well data show that gas-saturated, ...

Science.gov (United States)

Seismic stratigraphy based chronostratigraphic (SSBC) analysis of the Serbian Banat region allows the delineation of the spatial and stratigraphic relationships of the generally regressive and shallowing upward Neogene depositional fill of a tectonically unstable central portion of the Pannonian Basin. When geometrically restored in time and space, the sediment dispersal directions, sediment source directions, types of sedimentation breaks and the tectonic events influencing basin evolution can be delineated. For such an analysis the time-transgressive lithostratigraphic units used in the neighbouring Hungarian part of the Pannonian Basin are conveniently introduced based upon their characteristic seismic facies and constrained borehole log records as mappable seismic stratigraphic sequence units, termed "seismic operational sequences". The respective Neogene stage and operational sequence equivalents (Hungarian lithostratigraphic units or formations) are the ...

Energy Technology Data Exchange (ETDEWEB)

Reinterpretation of the South Florida basin reveals that it was a keep-up carbonate shelf during the Lower Cretaceous. Until the Cenomanian, it was connected to the Bahamas and the Cay Sal Bank north of Cuba. The Cenomanian sea level rise was at least partially responsible for the formation of the Florida Straits, isolating the platform. The combination of an abrupt worldwide rise in sea level and subsidence caused the South Florida platform to founder, ending shallow-water and evaporitic sedimentation over the majority of the shelf. The Cay Sal and Bahamian platforms remained as active shallow shelves separated by the Old Bahamas Channel. The Lower Cretaceous sediments are characterized by shallow shelf limestones, dolomites, and evaporites (mostly anhydrite). The evaporite-rich sections, originally thought to represent basinal facies, are reinterpreted as supratidal to shallow subtidal evaporites, based on examination of core and cuttings. Influx of normal marine ...

Science.gov (United States)

The Cretaceous rudist-bearing carbonates of the Arabian Gulf region are proven exploration targets for hydrocarbons and form the reservoirs of a number of giant fields, including Bu Hasa, Fateh, Fahud, Idd El Shargi, Rumaila, Shaybah, and Shah. Rudist buildups occur in three principal formations: (1) Aptian Shuaiba, (2) Cenomanian Mishrif, and (3) Maastrichtian Simsima. A regional subaerial unconformity marks the upper boundary of each of these formations. Associated with the rudists that dominate the Shuaiba Formation are calcareous algal crusts, foraminifera, and echinoid plates, which accumulated in mudstone, packstone, and carbonate sands. The Mishrif Formation contains mollusk fragments, bioclasitc packstones to grainstones, miliolid and nonrudist bivalves in muddy limestones, and rudist (mainly radiolitids and caprinids) conglomeratic floatstones, with fragmented rudists mixed with wackestone lithoclasts. The Mishrif sediments accumulated as a progradational, low-energy leeward ...

Energy Technology Data Exchange (ETDEWEB)

Ophiolitic rocks occur as wall rocks of the 2.7 Ga Louis Lake batholith near Atlantic City, Wyoming. All of the Archean rocks are strongly deformed and metamorphosed to a greenschist and amphibolite facies, but relict structures and textures are commonly preserved. These include the following, from west to east: (1) metadiabase with rare coarse-grained metagabbro; (2) ultramafic rocks and metagabbro; (3) amphibolite, locally pillowed, overlain(.) by pelitic schist, banded iron formation, and quartzite; and (4) pillow lavas, massive sills or flows, and minor metasedimentary rocks. Slice 1 locally contains parallel dike margins and rare metagabbro screens; these features suggest that it may represent a sheeted dike complex. Slice 2 locally contains ultramafic rocks having relict cumulus textures and igneous layering, corresponding to the cumulus portion of an ophiolite. The pillow lavas of slice 4 and possibly slice 3 are interpreted as comprising the extrusive ...

Energy Technology Data Exchange (ETDEWEB)

Naval Petroleum Reserve No. 3 (NPR-3), also known as Teapot Dome, is a government-owned oil field in Natrona County, Wyoming. It is an asymmetrical anticline located on the western edge of the Powder River Basin, just south of the Salt Creek Anticline. Production started in 1922, and today the field is a marginally economic stripper field with average production of less than 3 BOPD (0.5 m{sup 3}/D) per well. Total field production is about 1,800 BOPD (286 m{sup 3}/D). The Second Wall Creek Formation was waterflooded from 1979 until June 1992 with poor results due to the extensive natural fracture system in this sandstone unit. Since water injection ceased, reservoir pressure has declined to very low levels. Liquids extraction and reinjection of the gas produced from high-GOR wells along the gas-oil contact continues, but the average gas cap pressure has fallen to approximately 150 psi (1.03 MPa) from an original pressure of 1,120 psi (7.72 MPa). Since the oil is ...

Energy Technology Data Exchange (ETDEWEB)

A hypothesis on the transition of a fully water-saturated coal bed methane reservoir from single-phase flow through unsaturated flow to the two-phase flow regime was developed and substantiated using field data. The concept of parameter measurement windows was introduced to obtain the required reservoir parameters from flow testing. A new empirical relationship for capillary pressure vs. saturation, referred to as the Fermi distribution, was developed and shown to fit the capillary pressure-saturation data for coal, sandstone, and other consolidated and unconsolidated materials. New approximate analytic solutions for flow to a sink from an infinite coal bed reservoir with desorbing methane have been developed and verified using numerical models for the following cases: (1) single-phase gas flow with desorption; (2) single-phase water flow in fully water-saturated and unsaturated flow regimes. A numerical model based on finite-difference method for simultaneous flow ...

Energy Technology Data Exchange (ETDEWEB)

Borehole stability is affected to a significant extent by the 3D local and regional stress field. Preliminary information on underground stress fields is provided by the World Stress Map, which shows N-NW stress at a depth of about 5000 m for the Voelkersen field. Earlier data analyses showed various directions in the range of 310-360 degrees. This was assumed to be a methodical error. An extensive study was carried out to evaluate and interpret all relevant information provided by borehole tests, borehole logs, and drill core measurements. [German] Standsicherheit und Stabilitaet von Bohrungen werden ganz wesentliche beeinflusst durch das umgebende dreidimensionale lokale und regionale Spannungsfeld. Fuer die Planung zukuenftiger (horizontaler) Bohrungen und die Erzeugung kuenstlicher Risse (''fracs'') spielt das Spannungsfeld eine bedeutende Rolle. Erste Hinweise ueber das regionale Spannungsfeld im Untergrund gibt die World Stress Map, in der ...

International Nuclear Information System (INIS)

A preliminary geologic investigation was conducted to determine if Triassic sedimentary rocks of the Sanford basin and Colon cross structure in North Carolina are favorable hosts for uranium deposits. Rocks of adjacent Carolina slate belt were also examined as a potential source of uranium. On the basis of favorability criteria for sandstone-type uranium deposits, and geologic and geophysical investigations of the study area, the most favorable sites for further investigation are (1) at the contacts between the Pekin and Cumnock and between the Pekin and Sanford Formations near the Colon cross structure and (2) at the base of the Jonesboro fault, which lies below the Sanford Formation, northwest of Sanford. The highly weathered granites southeast of the Jonesboro fault were a source of the detritus deposited on the cross structure and may have been a primary source of uranium. Uranium leached from the coarse sediment (Pekin Formation) of the cross structure may ...

Energy Technology Data Exchange (ETDEWEB)

A chronology for Paleocene strata of the Hinton area of west-central Alberta was developed from the integration of a magnetostratigraphic and palynostratigraphic study of the upper Coalspur and middle to upper Paskapoo strata in the Coal Valley to Obed Mountain area. The study resulted in the compilation of a complete section of 1100 m of strata with a maximum sediment accumulation rate of 250 m/m.y. Four new informal biostratigraphic units were used to highlight stratigraphically useful bioevents not previously recognized in existing zonations. These strata range in age from magnetochron 29r to 24r and palynozones Wodehouseia spinata Zone, Aquilapollenites reticulatus Subzone through the Pistillipollenite mcgregorii Zone. The 3 intervals with the most rapid changes in the palynoflora were the earliest Paleocene; the transition from the early to middle Paleocene; and in the late Paleocene. Each coincides with critical times in basin development, notably the initiation of regionally ...

Energy Technology Data Exchange (ETDEWEB)

This study of the hydrogeology of Chicken Creek Canyon wasconducted by the Environmental Restoration Program (ERP) at LawrenceBerkeley National Laboratory (LBNL). This canyon extends downhill fromBuilding 31 at LBNL to Centennial Road below. The leading edge of agroundwater tritium plume at LBNL is located at the top of the canyon.Tritium activities measured in this portion of the plume during thisstudy were approximately 3,000 picocuries/liter (pCi/L), which issignificantly less than the maximum contaminant level (MCL) for drinkingwaterof 20,000 pCi/L established by the Environmental ProtectionAgency.There are three main pathways for tritium migration beyond theLaboratory s boundary: air, surface water and groundwater flow. Thepurpose of this report is to evaluate the groundwater pathway.Hydrogeologic investigation commenced with review of historicalgeotechnical reports including 35 bore logs and 27 test pit/trench logsas well as existing ERP information from 9 bore logs. This was ...

Energy Technology Data Exchange (ETDEWEB)

The geothermal resources of the Wind River Basin were investigated. Oil-well bottom-hole temperatures, thermal logs of wells, and heat flow data have been interpreted within a framework of geologic and hydrologic constraints. Basic thermal data, which includes the background thermal gradient and the highest recorded temperature and corresponding depth for each basin, is tabulated. Background heat flow in the Wind River Basin is generally insufficient to produce high conductive gradients. Only where hydrologic systems re-distribute heat through mass movement of water will high temperatures occur at shallow depths. Aquifers which may have the confinement and structural characteristics necessary to create such geothermal systems are the Lance/Fort Union, Mesa Verde, Frontier, Muddy, Cloverly, Sundance, Nugget, Park City, Tensleep, Amsden, Madison, Bighorn, and Flathead Formations. Of these the Tensleep Sandstone and Madison Limestone are the most attractive in terms ...

Energy Technology Data Exchange (ETDEWEB)

Computation of effective flow properties of fluids in porous media based on three dimensional (3D) pore structure information has become more successful in the last few years, due to both improvements in the input data and the network models. Computed X-ray microtomography has been successful in 3D pore imaging at micron scale, which is adequate for many sandstones. For other rocks of economic interest, such as chalk and diatomite, submicron resolution is needed in order to resolve the 3D-pore structure. To achieve submicron resolution, a new method of sample serial sectioning and imaging using Focused Ion Beam (FIB) technology has been developed and 3D pore images of the pore system for diatomite and chalk have been obtained. FIB was used in the milling of layers as wide as 50 micrometers and as thin as 100 nanometers by sputtering of atoms from the sample surface. The focused ion beam, consisting of gallium ions (Ga+) accelerated by potentials of up to 30 kV and ...

Energy Technology Data Exchange (ETDEWEB)

Thirty-three measured sections of the Dinwoody Formation, including five from the literature, provide information on thickness, lithology, paleontology, and stratigraphic relations within the Wind River basin and immediately adjacent areas of Wyoming. Most of these sections are in Fremont County, and some lie within the Wind River Indian Reservation. The Dinwoody becomes progressively thinner eastward, from a maximum thickness of 54.6 m in the northwestern Wind River Mountains to zero near the Natrona County line. The formation is characterized by yellowish-weathering, gray siltstone and silty shale. Variable amounts of limestone, sandstone, gypsum, and claystone are also present. Marine bivalves, gastropods, brachiopods (Lingula), and conodonts are common in the western part of the study area, but are absent to the northeast in gypsiferous strata, and near the eastern limit of Dinwoody deposition. The Dinwoody in the Wind River Basin area was deposited ...

Energy Technology Data Exchange (ETDEWEB)

The main objective of the pilot Coal Compilation Project is to provide coal resource maps to stimulate and support industry exploration programs, and assist government in matters of resource management. An essential feature of the program is the use of cost effective Geoscience Information System (GSIS) technology that allows the database and various thematic maps to be analyzed, updated, and displayed with complete flexibility at any scale. This report describes the main features (geology, exploration history, coal occurrences, coal quality etc.) of the study area, map sheet NTS 83F/5 (Entrance), and includes a copy of the 1:50,000 scale map produced. The study area is located in west-central Alberta and contains coal measures deposited within thick successions of sandstones, siltstones, shales and conglomerates. These coal-bearing sequences are part of the Lower Cretaceous Luscar Group, Upper Cretaceous Brazeau Formation and Paleocene Coalspur Formation. The ...

Energy Technology Data Exchange (ETDEWEB)

Hydrocarbon recovery efficiency is controlled by reservoir heterogeneities resulting from geometric arrangements of strata, or {open_quotes}stratal architecture{close_quotes}. Traditional reservoir characterization relates depositional systems to stratal architecture. High-resolution sequence stratigraphy of outcrop analogs provides a chronostratigraphic framework for evaluating accommodation conditions of depositional systems. Key stratigraphic surfaces and/or correlative strata define a hierarchy of chronostratigraphic units of different periodicities. The Upper Cretaceous Ferron Sandstone, an analog to high accommodation and sediment supply fluvial-deltaic reservoirs, comprises an intermediate-term stratigraphic sequence consisting of seven short-term stratigraphic cycles. Each short-term stratigraphic cycle contains fluvial- to storm-dominated shallow-marine deposits laterally replaced by distributary channel deposits. The Lower Cretaceous Fall River Formation, ...

Science.gov (United States)

Understanding climate development in the central Andes is important in determining the relationship between mountain range uplift and climate change. Recent work along the western margin of the central Andes has led to the development of two competing hypotheses: 1) that climate change is directly responsible for uplift or 2) that uplift controls climate change. In the first scenario, uplift results from increased friction at the plate boundary due to sediment-starvation of the trench which is a function of decreased run-off (particularly post 14 Ma) due to global cooling. In the second scenario progressive uplift of the Andean Cordillera during the Miocene resulted in a strong orographic effect with a concomitant rainshadow west of the Andes. To determine the relationship between climate change and uplift it is necessary to ascertain precisely, when the climate changed, the nature of that change and when uplift occurred. With respect to climate change a key question that has been ...