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- Volume 1, Issue 3, 1995
Petroleum Geoscience - Volume 1, Issue 3, 1995
Volume 1, Issue 3, 1995
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Recent developments in reservoir engineering and their impact on oil and gas field development
Authors R. H. Davies and H. NikoWith much of the reservoir engineering development activities prior to 1986 being directed to new processes such as EOR, reservoir engineering of today has, like the other petroleum engineering disciplines, become part of an integrated effort to extract the maximum amount of oil from a reservoir. We will discuss some of the new developments in reservoir engineering which had a real impact on oil field operations in Shell and on the working practices of the individual reservoir engineer. Examples of recent advances in reservoir engineering are: (1) progress in the field of measuring residual oil saturations to water under representative conditions which will enable a more realistic assessment of trapped/bypassed oil in water floods such as those in large North Sea fields; (2) improved understanding of the production behaviour of horizontal wells based on analytical and numerical modelling which led to successful applications in Gabon and Oman; (3) advances in our understanding of production in naturally fractured reservoirs which provided the basis for a unique field experiment in the Natih Field in Oman; (4) understanding of the mechanism of fracturing in water injection wells, a process which has large cost-saving potential. The one factor largely responsible for the change in working practices of individual reservoir engineers is the availability of modern integrated IT technology. Moreover, working with uncertainty in a structured way has become routine in a reservoir engineer's work.
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Parameter estimation in flexural plate motion; elastic, plastic-elastic and thermo-elastic models applied to the Chukchi Basin, Alaska
More LessModels are presented of flexural plate basement motion (elastic, plastic-elastic and thermo-elastic) due to: (1) compressive or extensional stress; (2) variation of lithospheric basement density along the flexural plate; (3) spatial variations of plate rigidity; and (4) variations of initial plate angle, hinge point position, plate length, initial end load and plate curvature. A non-linear inverse method determines parameters. Synthetic test results and a case history from the Central Chukchi Basin illustrate the accuracy and resolution of the inversion procedure. The Central Chukchi Basin has an unloaded geometry mainly controlled by a Palaeozoic fault system. Plastic or thermal effects produce a narrow unloaded basin geometry not conforming to the Paleozoic fault distribution or to the isopach map of the Upper Ellesmerian sediments. Inverse elastic model results agree with both the known fault system development (from seismic data) and the direction of the Brooks Range motion.
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Subtle traps in extensional terranes; a model with reference to the North Sea
Authors Roy H. Gabrielsen, Ron J. Steel and Arvid NottvedtThe three stages of graben formation (initial, active stretching and thermal subsidence/sedimentary loading) offer different subsidence patterns, and, hence, different patterns of topography and deposition. The pre-rift stage (in rifts without pre-rift doming) is characterized by development of a broad basin with well developed axial and secondary transverse sediment transport. Stratigraphic traps are uniform and display less variation than in the subsequent stages. During the active stretching stage the basin geometry becomes more varied. Rotational fault blocks parallel to the graben margin become activated, and active fault scarps contribute to the instability of the system and to sedimentary transport systems parallel to the graben axis. The active stretching stage generates a topographically complex depositional environment, and potentially offers a great variety of subtle traps. The thermal subsidence/sedimentary loading stage brings the basin back to a less complicated geometry, and several types of unconformity traps will characterize the transition from the active stretching to the cooling stage. The dominant sediment transport system is transverse to the rift axis. The variety in types of subtle traps again is lowered.
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Geological description of flow units in channel sandstones in a fluvial reservoir analogue (Loranca Basin, Spain)
Authors A. W. Martinius and R. A. NieuwenhuijsLithofacies heterogeneity in channel sandstones in a labyrinth-type reservoir outcrop are expressed by the nested correlation structure of experimental permeability semivariograms. First-rate correlation lengths are related to average set size or the average thickness of laterally accreted beds, second-rate correlation lengths to the average spacing of cosets or beds, and third-rate correlation lengths to the average spacing of surfaces truncating individual point bars within a meander loop. Three flow units are defined. Flow unit I comprises ribbon sandstone bodies and is characterized by large trough cross-stratified sets. Second-order bounding surfaces are dominant. Permeability is interdependent between two second-order bounding surfaces. Flow unit II comprises the lower part of meander loop sandstone bodies without grain size differences visibly expressed at the lateral accretion surfaces. Lithofacies and permeability characteristics are similar to flow unit I although the average set size and mean permeability are low. The average volume of flow unit II is largest. Flow unit III comprises the heterolithic upper part of meander loop sandstone bodies built up by ripple lamination in laterally accreted beds with distinct grain size changes. The latter form pronounced bounding surfaces and, significantly, determine two-dimensional permeability interdependency. The mean permeability is three times smaller than that of flow unit I. The spatial distribution of the flow units is mainly determined by climatic fluctuations from relatively humid to relatively arid conditions.
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Kinematics of deformation and petroleum system appraisal in Neogene foreland fold-and-thrust belts
Authors Francois Roure and William SassiForeland fold-and-thrust (FFT) belts are one of the remaining frontiers for hydrocarbon exploration where large discoveries can still be expected. A methodology is described to assess their petroleum potential. Oil generation, migration and trapping history are studied together with structural modelling. Structural reconstructions require the successive use of inverse models to restore geological or seismic sections to their initial, undeformed geometry, and forward models to simulate thrust development with time. The restoration of structural sections to their intermediate geometry, between the onset of compression and their present form, is an aid in reconstructing the burial maturation and diagenetic history of potential source rocks and reservoirs. Erosion and uplift are two competing factors that can delay hydrocarbon generation and must be accounted for in these simulations. Forward modelling is helpful in testing the validity of assumed migration pathways and traps. Complementary ID or 2D models are used to integrate the burial and thermal histories with the kinetic parameters of potential source rocks, providing the timing of oil generation and expulsion, and even simulation of fluid flow and migration processes in areas that are well constrained structurally. Coupling the kinematics of deformation of complex areas (fold-and-thrust belts) with thermal, maturation and expulsion modellings is possible. Future implementations in FFT belts will be required to address such important processes as fluid circulation and hydrocarbon migration, or dewatering and compaction of potential reservoirs. The use of these integrated techniques in regional examples is described in Neogene orogenic belts (Western Alps, Apennines, Outer Carpathians, Eastern Venezuela Basin) to explain the various habitats of oil and gas in FFT belts. Oil-source rock correlations help to identify very distinct productive horizons, either in the allochthon or in the underthrust foreland. Long migration pathways (more than 100 km) are identified during early stages of deformation, with migration of the oil toward the flexural bulge. Shorter migration pathways (10 to 20 km) toward the frontal structures of the fold-and-thrust belt are responsible for late-stage trapping.
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Vendian to Cambrian carbonate reservoir types of the Siberian Platform
More LessThree types of carbonate reservoir have been recognized in the central and southern part of the Siberian platform based on their structure, reservoir properties and the type of internal migration: multilayer, massive and single-layer. Facies conditions determined the sedimentation mechanisms: biogenic in normal salinity zones and chemogenic in higher salinity zones. Chemogenic sedimentation produced micritic dolomites and limestones with intercrystalline porosity, smaller pores and low porosity and permeability. Biogenic sedimentation resulted in the formation of large interstices and reservoir properties that are significantly higher. As a result of salinity changes, the reservoir properties of similar facies (shallow water, relatively deep water and reefal) worsen towards the south and southwest.
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The Tiffany and Toni oil fields, Upper Jurassic submarine fan reservoirs, South Viking Graben, UK North Sea
Authors Alison Kerlogue, Stephen Cherry, Howard Davies, Mark Quine and Giuseppe SpottiThe Tiffany and Toni fields lie at the western margin of the South Viking Graben in the Northern North Sea in UK Block 16/17. The reservoirs are composed of coarse clastic sediments of the Upper Jurassic Brae Formation, which were deposited by turbidity currents and debris flows in a submarine fan setting. The Brae Formation accumulated adjacent to the graben margin fault scarp and abuts pre-Jurassic rocks of the Fladen Ground Spur to the west. The Kimmeridge Clay Formation provides both the source of hydrocarbons and the seal for the reservoir.
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Volumes & issues
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Volume 30 (2024)
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Volume 29 (2023)
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Volume 28 (2022)
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Volume 27 (2021)
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Volume 26 (2020)
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Volume 25 (2019)
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Volume 24 (2018)
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Volume 23 (2017)
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Volume 22 (2016)
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Volume 21 (2015)
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Volume 20 (2014)
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Volume 19 (2013)
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Volume 18 (2012)
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Volume 17 (2011)
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Volume 16 (2010)
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Volume 15 (2009)
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Volume 14 (2008)
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Volume 13 (2007)
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Volume 12 (2006)
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Volume 11 (2005)
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Volume 10 (2004)
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Volume 9 (2003)
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Volume 8 (2002)
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Volume 7 (2001)
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Volume 6 (2000)
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Volume 5 (1999)
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Volume 4 (1998)
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Volume 3 (1997)
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Volume 2 (1996)
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Volume 1 (1995)