bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural controls on sedimentation in continental rifts
Authors: Lambiase J.J. , Bosworth W. 
Published: April 2008

Abstract
Structure and climate have each been proposed as the primary control on sedimentation in continental rifts. Numerous Phanerozoic rifts spanning a wide range of inferred palaeoclimates have consistent relationships between structure and sedimentation, and between structural evolution and stratigraphic sequences. Six principal structural features strongly influence sedimentation patterns in rifts. (1) Topographically high accommodation zones segment rifts into 50–150 km long structural half-graben, each one a discrete depocentre. (2) Reactivation of pre-existing structural elements commonly controls the location and orientation of accommodation zones. Drainage systems outside the rift then may be captured and diverted towards the rift axis, establishing some accommodation zones as input points for sediment. (3) Footwall uplift at main border faults directs most drainage away from young rifts. Along the rift flanks, uplift is minimized at accommodation zones, enhancing their role as sediment input points. (4) Gentle roll-over of topography on flexural margins produces drainage systems that are generally small, and that do not introduce large amounts of sediment into the rift. (5) Breakup of the basin floor into elongate, rift-parallel fault blocks greatly enhances along-axis sediment transport. (6) Development of fault relay zones and transfer faults localizes down-dip sediment movement. These structural controls occur in the present-day low latitude rifts of East Africa, where climate ranges from arid to humid. Similar features have been identified in ancient rifts that are interpreted to span a comparable range in climates. Clearly, climate is important in determining the sedimentary history of continental rifts. The present study indicates that climatic effects, however, are superimposed on the fundamental structural geometries that evolve during rifting.
Characteristics of selected Palaeogene and Cretaceous lacustrine source basins of Southeast Asia
Authors: Williams Harold H. , Fowler Martin , Eubank Roger T. 
Published: April 2008

Abstract
Lacustrine rift systems have sourced a large portion of the known hydrocarbon reserves in Southeast Asia, and their importance as exploration targets is well established. Our exploration experience has shown that the source rock quality, maturation and the presence of a post-rift marine sag sequence containing reservoirs are the most important factors controlling the hydrocarbon potential of these basins. However, variability in rift architecture, depositional processes, sedimentary geochemistry and thermal history of rift systems is poorly documented in the published literature. Often in the early stages of exploration of rift basins, data available to assess their prospectivity is limited. A more extensive data base of analogues to draw on, particularly non-producing analogues, would allow the explorationist to make better interpretations. In this paper the rift architecture, depositional sequences and sedimentary geochemistry of four Palaeogene and one Cretaceous/Palaeogene graben systems in Indonesia (Sumatra), Thailand and China are described. The graben described are in the Bandar Jaya Basin in South Sumatra, Kampar Kanan Basin in Central Sumatra, Ombilin Basin in West Sumatra, Phetchabun Basin in North Thailand and Dongting Basin in China. These graben cover a range of rift architectures related to wrench tectonic regimes and represent depositional sequences deposited in freshwater to saline lacustrine environments in deep to shallow water lakes. Climatic conditions range from arid in Dongting to tropical throughout Indonesia and Thailand. The geochemical characteristics of the source rocks in these graben are described in the context of their depositional systems.
Karoo Rift basins of the Luangwa Valley, Zambia
Authors: Banks N. L. , Bardwell K. A. , Musiwa S. 
Published: April 2008

Abstract
An integrated study of the Luangwa Valley Karoo Rift basins of NE Zambia has been carried out. Approximately 3000 km of seismic data were used in addition to gravity and aeromagnetic surveys and data from two exploration wells. The present day Luangwa Valley is underlain by two opposing Karoo half-graben separated by a central accommodation or transfer zone. The basins contain up to 8000m of Permo-Triassic, mainly clastic, sediments. The Lower Karoo consists of basal glacial deposits overlain by a sequence of interbedded coal, shale and siltstone, and capped by a very thick (up to 5000 m) lacustrine section of interbedded siltstone and mudstone. The Upper Karoo consists of interbedded coarse sandstones and siltstones thought to be of braided stream and flood plain origin. Rifting appears to have been initiated in the early Permian. The timing of subsequent rifting and inversion events has been related to strike-slip movements along the Mwembeshi Shear Zone, a major Precambrian lineament. Study of the seismic data has revealed a number of structural and stratigraphic plays in the basin. The best potential for hydrocarbon accumulation occurs within the lowest part of the Karoo section where source rocks and reservoirs are postulated in the Luwumbu Formation and the lowest part of the Madumabisa Mudstone. Since these intervals were not reached by either of the exploration wells drilled it is felt that the hydrocarbon potential of the Luangwa Graben has not yet been fully tested.
Hydrocarbon habitat in the Songliao Rift Basin, China
Authors: Desheng Li 
Published: April 2008

Abstract

The Songliao Basin covers an area of 260 000 km
2
and is a Jurassic-Cretaceous rift depression basin which overlies basement that is composed of Palaeozoic metamorphic rocks and Hercynian granites. The basin has undergone four evolutionary stages, including: (1) the Triassic to middle Jurassic Thermo-Arch Stage; (2) the Late Jurassic to Early Cretaceous Taphrogenic Stage; (3) the Early to Late Cretaceous Depression Stage; and (4) the Late Cretaceous to Quaternary Shrink-Folding Stage

The Lower Cretaceous non-marine Qingshankou Formation provides very favourable oil and gas source rocks. The supergiant Daqing Oilfield, discovered in 1959, is located in the central anticline belt of the basin. Reservoir formations are Lower Cretaceous S, P and G Reservoir Group sandstones. Since 1976, Daqing Oilfield has yielded more than 50 million tons of crude oil per year (one million barrels/day) and has maintained its peak production for 17 years. Its cumulative oil production by the end of 1992 was 1.18 billion tons (8.2 billion barrels).
Application of sedimentology to the development and extraction of deep-mined coal
Authors: Fulton Iain M. , Guion Paul D. , Jones Neil S. 
Published: April 2008

Abstract
Most deep-mined coal in the UK comes from the Westphalian A and B (Langsettian-Duckmantian) of the coalfields of the Pennine Basin, in which several sedimentary facies have been identified. Deep mining of coal may be divided into four main operations: shaft sinking and driving of access drifts; drivage of underground roadways; excavation of coal faces; and the provision of temporary underground storage. The prediction of the lithological, geometrical and geotechnical properties of the various sedimentary facies likely to be encountered during mining is important for the success of all these operations.
Roadway location may be influenced by the geotechnical attributes of the sedimentary facies, which also govern the type of machinery and methods used to cut and support the roads. The thickness, quality and continuity of the coal, and the properties of the roof and floor, are important in selecting the location of longwall faces and in their productivity. Facies composed of strong sedimentary rocks are likely to be the most suitable for the location of staple shafts and bunkers for coal storage. The geotechnical properties of each of the sedimentary facies is described, with particular reference to their excavation and support characteristics, and the discontinuities of sedimentary origin that are likely to be present. Distal lacustrine delta facies appear to provide the optimum roof conditions for coal faces and roadways.
A simple scheme for the prediction of the sedimentary facies which may influence mining is presented, and a variety of mapping techniques, including facies maps, isopach maps and palaeocurrent analysis, are outlined. An improved knowledge of the properties and distribution of the various sedimentary facies at a mine site should lead to improved productivity and a reduction in risks and costs.
Discrimination of regionally extensive coals in the Upper Carboniferous of the Pennine Basin, UK using high resolution sequence stratigraphic concepts
Authors: Hampson Gary 
Published: April 2008

Abstract

During the late Carboniferous, the Pennine Basin, UK was a thermally subsiding, intracratonic basin with little active tectonism. The sedimentary fill of the basin consists of coarsening-upward coal-bearing deltaic cyclothems bounded by widespread faunalconcentrate condensed horizons. The Yeadonian (Namurian G
1
) Rough Rock Group comprises three such cyclothems that have been studied at outcrop and in core using detailed sedimentological logging and then applying high resolution sequence stratigraphical concepts. Key surfaces and systems tracts are recognized and a sequence stratigraphic framework is constructed using these criteria and incorporating basin biostratigraphy and palaeogeography.

Two regionally extensive coals are present in the Rough Rock Group. They formed under relatively long-lived, basin-wide conditions of (1) clastic sediment starvation and (2) rising water-table, creating accommodation space for peats to accumulate and be preserved in mires. These conditions are characteristic of deposition in transgressive systems tracts and in the context of the Rough Rock group sequence stratigraphic framework these coals are identified as up-dip equivalents of initial flooding surfaces. This example raises wider implications for the discrimination of other regionally extensive coals in the upper Carboniferous strata of the Pennine basin using high resolution sequence stratigraphic concepts.
Overview of the influence of syn-sedimentary tectonics and palaeo-fluvial systems on coal seam and sand body characteristics in the Westphalian C strata, Campine Basin, Belgium
Authors: Dreesen Roland , Bossiroy Dominique , Dusar Michiel , Flores Romeo M. , Verkaeren Paul 
Published: April 2008

Abstract
The Westphalian C strata found in the northeastern part of the former Belgian coal district (Campine Basin), which is part of an extensive northwest European paralic coal basin, are considered. The thickness and lateral continuity of the Westphalian C coal seams vary considerably stratigraphically and areally. Sedimentological facies analysis of borehole cores indicates that the deposition of Westphalian C coal-bearing strata was controlled by fluvial depositional systems whose architectures were ruled by local subsidence rates. The local subsidence rates may be related to major faults, which were intermittently reactivated during deposition. Lateral changes in coal seam groups are also reflected by marked variations of their seismic signatures. Westphalian C fluvial depositional systems include moderate to low sinuosity braided and anastomosed river systems. Stable tectonic conditions on upthrown, fault-bounded platforms favoured deposition by braided rivers and the associated development of relatively thick, laterally continuous coal seams in raised mires. In contrast, rapidly subsiding downthrown fault blocks favoured aggradation, probably by anastomosed rivers and the development of relatively thin, highly discontinuous coal seams in topogenous mires.
Palaeoecological models, non-uniformitarianism, and tracking the changing ecology of the past
Authors: Bottjer David J. , Campbell Kathleen A. , Schubert Jennifer K. , Droser Mary L. 
Published: April 2008

Abstract
Palaeoecological models are commonly used by palaeontologists and sedimentary geologists to reconstruct ancient palaeoenvironments. In order to illustrate the ways in which palaeoecological models develop as new information is discovered, four examples are discussed: (1) reefs and fossil cold seeps; (2) biofacies models for strata deposited in ancient oxygen-deficient environments; (3) palaeoenvironmental distributions of post-Ordovician stromatolites; and (4) onshore-offshore trends of trace fossils. The development of physical sedimentological and geochemical criteria that can independently be used for evaluating ancient depositional environments provides a base line with which to assess palaeoecological change through geological time. Thus, the possibility now exists to free palaeoecological models and the study of ancient ecology from traditional uniformitarianism and Lyell’s dictum that the ‘present is the key to the past’, so that palaeoecological models may be developed which are useful for segments of time not anchored in the present. This approach will also be essential for evaluating the changing ecology of the past, which at present is only poorly understood. Future development and independent testing of such palaeoecological models will allow a more complete appreciation of the changing roles of environment, ecology and evolution in the history of life.
Fossil indicators of nutrient levels. 2: Evolution and extinction in relation to oligotrophy
Authors: Brasier M. D. 
Published: April 2008

Abstract
An overview of hypotheses on the impact of nutrients on biosphere history reveals the need for quantitative fossil indices for oligotrophy. Emphasis is given to indicators for endosymbiosis in relation to oligotrophic regimes, and a middle Eocene case history is selected for closer examination. Quantitative data, relating to changes in cellular integration in foraminifera are consistent with a catastrophic shift from highly oligotrophic towards eutrophic conditions, associated with global cooling near the end of the middle Eocene.
Organisms and the substrate: response and effect
Authors: Goldring Roland 
Published: April 2008

Abstract

Benthic organisms are invaluable in the interpretation of ancient environments. The principles of animal behaviour at and below the substrate surface (e.g. encrustation, burrowing, boring, feeding) are well established. Three areas in particular are currently being developed: (1) Ichnofabrics are replacing ichnofacies in facies interpretation. The use of archetypal ichnofacies is abandoned in favour of an integrated approach (including palynology and geochemical analysis), using autecology followed by synecology and synthesis, and ichnofabric analysis; this provides greater resolution; (2) Comparisons of deep-sea studies with ancient bathyal sediments are leading to a better understanding of turbidite facies: the factors involved in the formation of the complex tiering of the pre-event ichnocoenoses and those involved in the colonization of the turbidite. The morphology and ethology of several shallow and deep-water ichnotaxa (e.g.
Zoophycos, Paleodictyon
) are still imperfectly understood; (3) The
fabric
of shell and skeletal concentrations reflects the dynamics of the final depositional environment, and the
taphonomic signature
, in the main, the environmental conditions under which the shells formed and accumulated. Together, these aspects, and their relative stratigraphic frequency, reflect regional patterns of hydraulics and basin dynamics. Advances in the appreciation of time-averaging should provide renewed interest in research into palaeocommunities.

The stratigraphical distribution of hardgrounds remains an enigma and their potential significance for basin analysis awaits full evaluation. Two groups of hardground are recognized: whether they formed under omission and wave bevelling, or solely under omission.
Which sub-seismic heterogeneities influence waterflood performance? A case study of a low net-to-gross fluvial reservoir
Authors: Jones Alistair , Doyle James , Jacobsen Torgrim , Kjønsvik Dagrun 
Published: April 2008

Abstract
Waterflood performance in a fluvial reservoir is examined to assess which aspects of the reservoir are important to describe for accurate simulation of recovery performance. The study is based on a low net-to-gross fluvial reservoir and we consider the influence of sedimentary heterogeneities which are sub-seismic-scale in a full-field model.
A detailed hierarchical 3D geological model is developed and flow properties are upscaled. Particular attention is given to representing the influence of cross-stratification. A screening study is then conducted to assess which heterogeneities and scales have the greatest influence on recovery predictions. By using experimental design the influence of a large number of factors is examined in an efficient manner.
The results show that parameters describing channels and channel belts have the greatest influence. Somewhat surprisingly, the number of channels in a belt and their width and thickness has at least as much influence on sweep efficiency as net-to-gross and the stacking of belts. In addition to the influence of these large-scale heterogeneities, capillary effects at the laminae scale within cross-stratification have a significant effect on recovery.
Early identification of important heterogeneities will allow for more efficient field exploitation. The strongest impact of this approach may be to focus data collection early in the life of a field on the most important types of heterogeneities to be expected for a given depositional and stratigraphic setting.
Stress effects on reservoir flow: — Numerical modelling used to reproduce field data
Authors: Heffer K. J. , Koutsabeloulis N. C. 
Published: April 2008

Abstract
Empirical field data show a strong correlation between the preferred directionality in many normal IOR floods and the local modern-day state of earth stress. The conjecture that this correlation is due to the activation of natural fractures by changes in the stress state induced by the flood has been tested with coupled modelling of fluid flow and geomechanical deformaton. The results of initial generic modelling incoroporating thermal stresses from cold water injection showed good agreement with the details of the field data, lending strong support to the conjecture. The modelling indicated that directionality trends increasingly towards the major horizontal stress axis as a flood progresses. The new coupled modelling capability provides an improved tool for planning well patterns, infill drilling and flood management.
Prudhoe Bay: infill drilling in gravity dominated WAG floods
Authors: Wilcox T. C. , Polzin M. W. , Kuo S. S. , Humphrey K. J. 
Published: April 2008

Abstract
Many horizontal miscible gas floods experience relatively low vertical sweep efficiency due to gravity segregation of the injected solvent and reservoir liquids. This is true for the Prudhoe Bay Miscible Gas Project (PBMGP) in which the enriched-hydrocarbon miscible injectant (MI) is expected to sweep only approximately 300f the reservoir volume in the project areas. The Prudhoe Bay reservoir has a relatively thick oil column, high inter-sand vertical permeability, high net-gross, and is generally developed on 80 acre (324 = 103 m2) well spacing.
An infill drilling project was implemented in the Northwest Fault Block (NWFB) area of Prudhoe Bay (Fig. 1) to improve solvent sweep efficiency and increase EOR reserves. This project differs from many EOR infill drilling projects in that most of the additional recovery is attributable to EOR, with minimal improvement in waterflood recovery.
The infill project is feasible because the reservoir is relatively thick, and sufficient EOR reserves are obtained from miscible displacement around new injectors. A significant increase in flood rate can also occur, resulting in production acceleration. Results of the project will guide analysis of infill drilling in other EOR areas at Prudhoe. The Prudhoe Bay Miscible Gas Project is the world’s largest enriched-hydrocarbon miscible gas flood, and is located in northern Alaska, USA.
Laboratory evaluation and field tests of a silicate gel system intended for use under North Sea conditions
Authors: Kristensen R. , Lund T. , Titov V. I. , Akimov N. I. 
Published: April 2008

Abstract
This paper describes results from laboratory experiments and field tests, using basic Na-silicate. The work described has been performed as a part of the programme to qualify chemical systems for large-scale in-depth permeability modification processes in the North Sea.
Gelling properties of basic silicate solutions have been measured as a function of pH, silicate concentration and temperature. The gelation times decrease with decreasing pH and increasing concentration. Increasing temperature will also give shorter gelation times. Adsorption of silicate is found to be linearly increasing with increasing silicate concentration.
The rock buffer capacity is found to be strongly dependent on mineralogy. As an example, kaolinite has a buffer capacity more than ten times higher than other minerals. Both adsorption and buffer capacity will strongly influence the composition and gelation properties of the silicate solution in an in-depth treatment.
In total, three field tests have been performed. The test area was chosen on the basis of Gullfaks reservoir data. From a one well formation test, field information was obtained on silicate adsorption and buffer capacity. The field results confirmed the laboratory data. The other two field pilots were run to obtain information on an optimum injection scheme for injection of silicate solutions into reservoirs with brines with high salinity and hardness. A preflush of fresh water was found to condition the critical reservoir parameters and allow for good injectivity of the basic silicate solution. The potential of water shut-off treatments of high watercut producers was examined in two well tests. The wells produced before treatment at a watercut of 96%. In one of the wells the watercut was reduced to less than 10% at the same fluid production rate and the watercut has been lower than 20% for more than eight months after treatment.
An investigation of the vertical sweep efficiency of steam drive in a layered reservoir
Authors: Godderij R. R. G. G. , Gümrah F. , Palmgren C. T. S. , Bruining J. 
Published: April 2008

Abstract
This paper presents results obtained in a theoretical and experimental study on the efficient use of steam injection for the recovery of oil from a layered, dipping reservoir.
For the experimental part, we use a scaled transparent vacuum model. An infrared camera follows the evolution of the steam condensation front. For the theoretical part, we use an interface model to describe the behaviour of the steam condensation front. Two approximations for the flow field are examined, leading to a Dietz-Dupuit model and a cross-flow model respectively.
The theoretical results are compared to the experimental values to investigate the validity of the models. We conclude that vertical sweep efficiency improves with dip. Furthermore the Dietz-Dupuit model leads to a reasonable agreement in the case with a high permeable layer at the top. With the high permeable layer at the bottom, however, discrepancies occur. The simple cross-flow model shows agreement with all of the gravity stable experiments, but lacks a firm physical basis.