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Jitao Chen - One of the best experts on this subject based on the ideXlab platform.
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soft sediment deformation structures in cambrian siliciclastic and carbonate storm deposits shandong province china differential liquefaction and fluidization triggered by storm wave loading
Sedimentary Geology, 2013Co-Authors: Jitao ChenAbstract:Abstract This paper focuses on soft-sediment deformation structures (SSDS) in both siliciclastic and carbonate storm deposits of the Cambrian Mantou and Chaomidian formations (Shandong Province, China) in order to understand their deformation mechanisms and possible triggers. Siliciclastic SSDS (e.g., sand volcanoes and pillows) and carbonate SSDS (e.g., sedimentary dykes, Grainstone-matrix breccias, deformed cross-beddings, and marlstone-matrix breccias) occur exclusively in hummocky cross-stratified fine sandstone and peloidal Grainstone, respectively. The siliciclastic SSDS formed in porous and permeable surface sediment, whereas the carbonate SSDS formed under shallow burial conditions when early marine cementation prevailed. The various deformation structures resulted mainly from differences between siliciclastic and carbonate sediment conditions and resulting deformation mechanisms. Sand volcanoes formed by upward extrusion of over-pressured fluidized sandy sediment, whereas sand pillows resulted from upward injection of lower density muddy sediment into overlying liquefied sandy sediment. Sedimentary dykes and Grainstone-matrix limestone breccias formed as a result of differential liquefaction and fluidization of heterogeneously cemented carbonate sediment, whereas deformed cross-beddings and marlstone-matrix limestone breccias developed by the thixotropic liquidization and injection of clayey sediment, and further disruption of thin peloidal layers. Sedimentary facies analysis and analysis of the physical processes indicate that the SSDS were most likely caused by cyclic loading of storm waves.
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Demise of an extensive biostromal microbialite in the Furongian (late Cambrian) Chaomidian Formation, Shandong Province, China
Geosciences Journal, 2012Co-Authors: Jeong-hyun Lee, Jitao Chen, S K ChoughAbstract:This study focuses on an extensive biostromal microbialite (10–20 m in thickness and over 6,000 km^2 in area) and the overlying Grainstones in the Furongian Chaomidian Formation, Shandong Province, China in order to understand the demise of the microbialite. The microbialites are characterized by centimeter-to decimeter-scale maze-like maceria structures and/or chaotic mesostructures. According to the megastructures of microbialites and the proportion of non-microbial carbonate sediment, the biostromal microbialite is generally divided into the lower and the upper parts, separated by a distinct surface. The lower part is laterally continuous and generally flat-bedded, whereas the upper part shows variable domal megastructures and locally co-occurs with abundant non-microbial carbonate sediment. The entire microbialite bed is sharply overlain by Grainstone-dominated deposits via an erosion surface which is either irregular with significant relief or flat with hematitic coating. The lower part of the biostromal microbialites with flat-bedded megastructures most likely deposited contemporaneously during sea-level highstand in the early middle Furongian, as evinced by well-correlated flat-bedded units separated by distinct bounding surfaces. The microbialites formed regional topographic variation, generally deepening toward southeast. The flat-bedded microbialites were drowned by subsequent rapid rise in sea level. In the topographic highs, the microbialites caught up with sea-level rise, forming large-scale domal megastructures. In the topographic lows, however, domal microbialites formed together with abundant non-microbial sediment, which were frequently reworked by storm-induced waves and currents. Subsequent deposition and migration of coarse-grained non-microbial sediment during sea-level rise terminated the entire microbialites.
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limestone pseudoconglomerates in the late cambrian gushan and chaomidian formations shandong province china soft sediment deformation induced by storm wave loading
Sedimentology, 2009Co-Authors: Jitao Chen, Sung Kwun Chough, Seung Soo ChunAbstract:This paper focuses on the formative processes of limestone pseudoconglomerates in the Gushan and Chaomidian Formations (Late Cambrian) of the North China Platform, Shandong Province, China. The Gushan and Chaomidian Formations consist mainly of limestone and shale (marlstone) interlayers, wackestone to packstone, Grainstone and microbialite as well as numerous limestone conglomerates. Seventy-three beds of limestone pseudoconglomerate in the Gushan and Chaomidian Formations were analysed based on clast and matrix compositions, internal fabric, sedimentary structures and bed geometry. These pseudoconglomerates are characterized by oligomictic to polymictic limestone clasts of various shapes (i.e. flat to undulatory disc, blade and sheet), marlstone and/or Grainstone matrix and various internal fabrics (i.e. intact, thrusted, edgewise and disorganized), as well as transitional boundaries. Limestone pseudoconglomerates formed as a result of soft-sediment deformation of carbonate and argillaceous interlayers at a shallow burial depth. Differential early cementation of carbonate and argillaceous sediments provided the requisite conditions for the formation of pseudoconglomerates. Initial deformation (i.e. burial fragmentation, liquefaction and injection) and subsequent mobilization and disruption of fragmented clasts are two important processes for the formation of pseudoconglomerates. Burial fragmentation resulted from mechanical rupture of cohesive carbonate mud, whereas subsequent mobilization of fragmented clasts was due to the injection of fluid materials (liquefied carbonate sand and water-saturated argillaceous mud) under increased stress. Storm-wave loading was the most probable deformation mechanism, as an external triggering force. Subsequent re-orientation and rounding of clasts were probably prolonged under normal compactional stress. Eventually, disrupted clasts, along with matrix materials, were transformed into pseudoconglomerates by progressive lithification. Soft-sediment deformation is prevalent in alternate layers of limestone and mud(marl)stone and/or Grainstone, regardless of their depositional environments.
Charles Kerans - One of the best experts on this subject based on the ideXlab platform.
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deeper water deposition in intrashelf basins example from the lower cretaceous albian upper glen rose formation in the houston trough eastern texas
AAPG Bulletin, 2021Co-Authors: Peter Sotokerans, Robert G Loucks, Charles KeransAbstract:In easternTexas, a thick (150-200 ft) interval of Lower Cretaceous upper Glen Rose D strata was deposited in the Houston trough intrashelf basin landward of the Stuart City reef margin and seaward of the main eastern Texas intrashelf basin. The stratigraphic section in this intrashelf basin forms a primarily oil-bearing hydrocarbon system where porous Grainstones in the Alabama Ferry and Fort Trinidad fields were deposited coevally with organic-rich calcareous argillaceous mudstones. Here, we present evidence to suggest that the depositional setting within the Houston trough and the contained ooid Grainstone beds were of deeper-water origin (400-500 ft), below storm wave base. Further, the water column was stratified, allowing dysaerobic to anaerobic conditions to develop, fostering accumulation and preservation of organic matter. Grain-rich gravity flows consisting of ooids, intraclasts, and thin-walled mollusks, derived from the shallower shelf to the northwest, were deposited in the basin, forming the Alabama Ferry and Fort Trinidad fields. The upper Glen Rose interval is composed of lithofacies that vary laterally within the Houston trough. Five lithofacies are recognized on the basis of sedimentary features, texture, fabric, biota, and organic-matter content: (1) laminated to nonlaminated argillaceous lime mudstone to lime wackestone; (2) laminated to nonlaminated calcareous siliciclastic mudstone to siltstone; (3) intraclast–ooid skeletal lime packstone; (4) intraclast–bivalve–ooid lime Grainstone; and (5) oyster lime floatstone and rudstone. Grain-rich lithofacies laterally adjacent to and interbedded with organic-rich argillaceous lime mudstones and calcareous siliciclastic mudstones were previously interpreted as being deposited in a tidally influenced, high-energy, shallow-water shoal environment; however, reconstruction of the depositional setting and interpretation of the vertical and lateral distribution of lithofacies suggest that these lithofacies were deposited as grain-rich gravity flows into the deeper-water Houston trough. This interpretation suggests a new conceptual framework integrating facies models from submarine channel and fan complexes to explore for Grainstone reservoirs similar to Alabama Ferry and Fort Trinidad fields.
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late pennsylvanian glaciation evidence of icehouse conditions from canyon and cisco units midland basin texas
Marine and Petroleum Geology, 2018Co-Authors: Mahmoud Alnazghah, Charles KeransAbstract:Abstract The late Paleozoic has long been recognized a time of significant continental glaciation associated with high-frequency, high-amplitude glacioeustasy. Although, precise assessment of glacioeustatic amplitudes are difficult to extract from the stratigraphic record, best approximations may be possible by analyzing spatial and temporal distributions of depositional facies utilizing several wells across the study area. We used detailed sedimentologic description and depositional facies analysis from 12 wells and applied rigorous cycle stacking pattern analysis, exposure surfaces recognition and wireline logs to correlate timelines across the wells. On the basis of the high-resolution sequence stratigraphic framework built for the Scurry Area Canyon Reef Operators (SACROC) field, a highly-resolved glacioeustatic curve was generated for latest Desmoinesian to the latest Virgilian. Our eustatic curve suggests that the Missourian and Virgilian stages of the late Pennsylvanian are characterized by high frequency, high-amplitude eustatic fluctuations. The Missourian stage was a period dominated Grainstone-capped cycles that are isopachous and conformable. These cycles reflect a eustatic amplitude of at least 37 m with an average duration of 100 ka suggesting the dominance of short-term eccentricity signal. The Virgilian stage is far more complicated and is characterized by highly shingled cycles compared to the Missourian stage. Deeper water phylloid boundstone and calichified shoal complex Grainstones are juxtaposed next to each other which suggests a stronger eustatic amplitude (>40 m) compared to the Missourian stage. Although the eustatic amplitude of the Virgilian cycles is similar to those of the Missourian cycles, they have a longer frequency (343 ka) representative of long-term eccentricity. We conclude that the late Pennsylvanian stratigraphy of the SACROC field in the Midland Basin records extensive continental glaciation during the Missourian stage and increased and reached an acme during the Virgilian stage.
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a laterally accreting Grainstone margin from the albian of northern mexico outcrop model for cretaceous carbonate reservoirs
AAPG Memoir, 2004Co-Authors: David A Osleger, Roger J Barnaby, Charles KeransAbstract:Exceptional exposures of progradational platform margin slopes of Albian age were mapped along a 5-km, near-continuous, dip-oriented transect in northern Mexico with the goal of producing an outcrop model for analogous Cretaceous reservoirs. The study area at the El Cedral is located along the western margin of the Devils River Grainstone belt flanking the muddy, intrashelf Maverick Basin. Four relatively complete clinothems and portions of two adjacent clinothems are recognized in the Las Pilas Formation in the study area. The Las Pilas clinothems exhibit complex sigmoid-oblique geometries and have dimensions of 40–60 m of vertical relief, depositional dip angles of foreset beds ranging from 8 to 15, and dip-oriented lengths of 1–2 km. Internally, in foresets of clinothems, thick- to massively bedded, sigmoid- to oblique-shaped lenses exhibit overlapping, seaward-stepping patterns toward the southeast. The primary sediment fabrics of topset, foreset, and bottomset beds of the Las Pilas clinothems are Grainstones and grain-rich packstones. Coated grains are the predominant grain type, with subordinate amounts of micritized mollusk fragments and intraclasts. Porosity is predominantly moldic, but primary interparticle porosity is common. These lime sands were winnowed, coated, and micritized along the high-energy topsets of clinoforms before being exported seaward toward the breakpoint, where they cascaded onto the steep frontal slopes as sporadic grain flows or mass flows. The master bounding surfaces that define the clinothems likely represent episodes of nondeposition and abandonment of the surface, perhaps occurring during shifts in the locus of deposition laterally along the shoal margin. The architecture and composition of the Las Pilas clinoforms provide observable data for comparison with analogous subsurface reservoirs in the Aptian Shuaiba Formation (Bu Hasa field) and Cenomanian Mishrif Formation (e.g., Umm Adalkh field) of the Arabian Gulf.
Seung Soo Chun - One of the best experts on this subject based on the ideXlab platform.
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limestone pseudoconglomerates in the late cambrian gushan and chaomidian formations shandong province china soft sediment deformation induced by storm wave loading
Sedimentology, 2009Co-Authors: Jitao Chen, Sung Kwun Chough, Seung Soo ChunAbstract:This paper focuses on the formative processes of limestone pseudoconglomerates in the Gushan and Chaomidian Formations (Late Cambrian) of the North China Platform, Shandong Province, China. The Gushan and Chaomidian Formations consist mainly of limestone and shale (marlstone) interlayers, wackestone to packstone, Grainstone and microbialite as well as numerous limestone conglomerates. Seventy-three beds of limestone pseudoconglomerate in the Gushan and Chaomidian Formations were analysed based on clast and matrix compositions, internal fabric, sedimentary structures and bed geometry. These pseudoconglomerates are characterized by oligomictic to polymictic limestone clasts of various shapes (i.e. flat to undulatory disc, blade and sheet), marlstone and/or Grainstone matrix and various internal fabrics (i.e. intact, thrusted, edgewise and disorganized), as well as transitional boundaries. Limestone pseudoconglomerates formed as a result of soft-sediment deformation of carbonate and argillaceous interlayers at a shallow burial depth. Differential early cementation of carbonate and argillaceous sediments provided the requisite conditions for the formation of pseudoconglomerates. Initial deformation (i.e. burial fragmentation, liquefaction and injection) and subsequent mobilization and disruption of fragmented clasts are two important processes for the formation of pseudoconglomerates. Burial fragmentation resulted from mechanical rupture of cohesive carbonate mud, whereas subsequent mobilization of fragmented clasts was due to the injection of fluid materials (liquefied carbonate sand and water-saturated argillaceous mud) under increased stress. Storm-wave loading was the most probable deformation mechanism, as an external triggering force. Subsequent re-orientation and rounding of clasts were probably prolonged under normal compactional stress. Eventually, disrupted clasts, along with matrix materials, were transformed into pseudoconglomerates by progressive lithification. Soft-sediment deformation is prevalent in alternate layers of limestone and mud(marl)stone and/or Grainstone, regardless of their depositional environments.
Thomas Aigner - One of the best experts on this subject based on the ideXlab platform.
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high resolution anatomy of a Grainstone package in khuff sequence ks4 oman mountains sultanate of oman
GeoArabia, 2013Co-Authors: Marlene Marialouise Haase, Thomas AignerAbstract:This study is part of a large-scale outcrop analog study on Middle Permian to Lower Triassic Khuff-equivalent strata in the Oman Mountains, Al Jabal al-Akhdar, Sultanate of Oman. The Khuff outcrop equivalent can be divided into six sequences (Khuff sequences KS6 to KS1, from base to top). The main focus of this study is the description of the internal anatomy of the shoal Grainstone bodies in the lower part of Sequence KS4 (“lower KS4”). High-resolution sedimentological logging of three outcrop sections in wadis Sahtan, Bani Awf and Mistal yielded eight lithofacies types that were grouped into five facies associations. Lower KS4 strata were mainly deposited within a “shoal complex” of an epeiric carbonate ramp, resulting in a thick pile of up to 70 m of Grainstones that, on first sight, appear relatively homogeneous. However, detailed facies and microfacies analysis revealed their heterogeneous architecture on various scales: (1) Minor changes in depositional environments directly affected the type of carbonate grains (ooids versus peloids/cortoids versus bioclasts), leading potentially to highly variable pore systems (moldic versus interparticle versus intraparticle). (2) Vertically, detailed sequence-stratigraphic analysis revealed a higher-order of cyclicity (“mini-cycles”) on a decimeter- to meter-scale. Four mini-cycle types were recognized. (3) Laterally, facies changes, the amalgamation of Grainstone beds and mini-cycle pinch-outs were observed in 2-D correlations on a scale of a few kilometers. These different types of heterogeneities may contribute to varying production rates commonly observed in the subsurface KS4 reservoir.
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middle to upper khuff sequences ks1 to ks4 outcrop equivalents in the oman mountains Grainstone architecture on a subregional scale
GeoArabia, 2012Co-Authors: Bastian Koehrer, Thomas Aigner, Holger Forke, Michael PoppelreiterAbstract:The upper part of the Saiq and lower part of the Mahil formations in the Oman Mountains represent outcrop time-equivalents to the highly prolific, hydrocarbon-bearing subsurface Middle and Upper members of the Khuff Formation (K4–K1 reservoir intervals). In this study, four outcrops sections on the northern flank of the Oman Mountains (Al Jabal al-Akhdar region) are sedimentologically documented and integrated with the sequence-stratigraphic scheme initially developed at the Saiq Plateau reference section. The focus of this study is the description of the distribution and textural variation of Grainstones as potential reservoir facies on a subregional (ca. 60 x 40 km) scale. Stratigraphic cross-sections are constructed based on two sequence-stratigraphic orders: (1) one second-order supersequence (DS² 18) that provides a well-constrained general framework and (2) four third-order depositional sequences (KS1–KS4), within which subtle temporal and spatial variations of Grainstones occur. From these correlations predictive rules and correlation lengths of shoal bodies are extracted. The presence of Khuff Grainstones is strongly governed by stratigraphic position. Thicker and more abundant Grainstones are present during the early transgressive (KS4) and late regressive (KS1) portions of the supersequence. Thinner and less abundant Grainstones are present during the late transgression (KS3 and lower KS2) and early regression (upper KS2). They are absent around the second-order zone of maximum flooding (middle KS2). High lateral continuity of correlated cycle sets is observed, suggesting the absence of significant tectonic activity of the area during the Late Permian and Early Triassic. Integrated litho-, bio- and sequence stratigraphy provides a robust framework for correlation on a regional scale (ca. 700 km). The Oman Mountains area shows a more distal facies pattern on the Khuff platform compared with other Khuff reservoir sections in the region. This is especially evident around KS2 maximum flooding with muddy foreshoal and offshoal deposits in contrast to mainly oolitic shoal deposits in the Musandam (UAE) and offshore Fars (Iran) area.
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khuff sequences ks1 to ks4 Grainstone geobodies in the middle and upper khuff of the oman mountains sultanate of oman
Third Arabian Plate Geology Workshop, 2011Co-Authors: Bastian Koehrer, Thomas Aigner, Michael Zeller, Michael PoppelreiterAbstract:This study is part of a research project on Khuff Grainstone bodies carried out in the Al Jabal al-Akhdar area (Oman Mountains) in the Sultanate of Oman (Figure 1) and focusses on Khuff sequences KS1 to KS4. Its aim was to unravel the Khuff stratigraphic architecture on hierarchical scales to understand geometries and textural variation of Grainstones as potential reservoir bodies. Hierarchical static 3-D geological models were generated that visualise the sedimentary architecture of primary reservoir bodies using industry standard 3-D geomodelling software.
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khuff sequence ks4 high resolution anatomy of a middle khuff Grainstone package oman mountains sultanate of oman
Third Arabian Plate Geology Workshop, 2011Co-Authors: M Haase, Thomas Aigner, Holger ForkeAbstract:This outcrop study is part of a larger-scale project on the Saiq Formation in the Oman Mountains (outcrop analog of Khuff Formation), and focussed on the small-scale heterogeneities of the lower part of Khuff Sequence 4 (KS4). This interval is dominated by massive Grainstones that at first glance seem extremely homogenous with distinct trough cross-bedding detectable in spite of strong dolomitization. Serrated gamma-ray patterns made small-scale cycle interpretations difficult. Therefore a very detailed facies and sequence analysis was necessary to decipher the vertical microfacies make-up of the Grainstones and link it with potential pore types.
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field scale geometries of upper khuff reservoir geobodies in an outcrop analogue oman mountains sultanate of oman
Petroleum Geoscience, 2011Co-Authors: Bastian Koehrer, Thomas Aigner, Michael PoppelreiterAbstract:ABSTRACT This paper provides data on the lateral continuity and geometry of potential reservoir geobodies in outcrops of Upper Khuff Formation time-equivalent strata in the Jebel Al Akhdar area (Oman Mountains, Sultanate of Oman). It presents outcrop-based quantitative data of shoal-associated Grainstone bodies in a sequence stratigraphic framework on the scale of an average Khuff gas field. Such data may be useful for correlation and modelling of subsurface reservoirs. A stratigraphic correlation of five outcrop sections, based on facies, sequence analysis and gamma-ray pattern, was used as a framework for mapping the distribution and lateral extent of Grainstone geobodies over an area of 8 × 8 km. Four Grainstone bodies were traced laterally along distinct marker beds over several hundreds of metres. The stratigraphic architecture shows a general layer-cake pattern. The thickness and lateral extent of reservoir geobodies is strongly influenced by their stratigraphic position. High-energy shoal facies developed preferentially in the regressive parts of cycles of multiple hierarchies. Individual Grainstone bodies may reach a thickness of 6 m, and those thicker than 3 m extend across the area of interest. Clinoforms or shingle-type geometries were explicitly searched for, but were not present. The observed systematic variations in extent and two-dimensional sedimentary architecture of Khuff Grainstone bodies were used as input for 3D static facies modelling. Outcomes of this study have been used to reduce uncertainty on Grainstone geometries, production-scale correlation strategies and definition of lateral facies successions in subsurface models of the Khuff reservoir.
Michael Poppelreiter - One of the best experts on this subject based on the ideXlab platform.
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middle to upper khuff sequences ks1 to ks4 outcrop equivalents in the oman mountains Grainstone architecture on a subregional scale
GeoArabia, 2012Co-Authors: Bastian Koehrer, Thomas Aigner, Holger Forke, Michael PoppelreiterAbstract:The upper part of the Saiq and lower part of the Mahil formations in the Oman Mountains represent outcrop time-equivalents to the highly prolific, hydrocarbon-bearing subsurface Middle and Upper members of the Khuff Formation (K4–K1 reservoir intervals). In this study, four outcrops sections on the northern flank of the Oman Mountains (Al Jabal al-Akhdar region) are sedimentologically documented and integrated with the sequence-stratigraphic scheme initially developed at the Saiq Plateau reference section. The focus of this study is the description of the distribution and textural variation of Grainstones as potential reservoir facies on a subregional (ca. 60 x 40 km) scale. Stratigraphic cross-sections are constructed based on two sequence-stratigraphic orders: (1) one second-order supersequence (DS² 18) that provides a well-constrained general framework and (2) four third-order depositional sequences (KS1–KS4), within which subtle temporal and spatial variations of Grainstones occur. From these correlations predictive rules and correlation lengths of shoal bodies are extracted. The presence of Khuff Grainstones is strongly governed by stratigraphic position. Thicker and more abundant Grainstones are present during the early transgressive (KS4) and late regressive (KS1) portions of the supersequence. Thinner and less abundant Grainstones are present during the late transgression (KS3 and lower KS2) and early regression (upper KS2). They are absent around the second-order zone of maximum flooding (middle KS2). High lateral continuity of correlated cycle sets is observed, suggesting the absence of significant tectonic activity of the area during the Late Permian and Early Triassic. Integrated litho-, bio- and sequence stratigraphy provides a robust framework for correlation on a regional scale (ca. 700 km). The Oman Mountains area shows a more distal facies pattern on the Khuff platform compared with other Khuff reservoir sections in the region. This is especially evident around KS2 maximum flooding with muddy foreshoal and offshoal deposits in contrast to mainly oolitic shoal deposits in the Musandam (UAE) and offshore Fars (Iran) area.
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khuff sequences ks1 to ks4 Grainstone geobodies in the middle and upper khuff of the oman mountains sultanate of oman
Third Arabian Plate Geology Workshop, 2011Co-Authors: Bastian Koehrer, Thomas Aigner, Michael Zeller, Michael PoppelreiterAbstract:This study is part of a research project on Khuff Grainstone bodies carried out in the Al Jabal al-Akhdar area (Oman Mountains) in the Sultanate of Oman (Figure 1) and focusses on Khuff sequences KS1 to KS4. Its aim was to unravel the Khuff stratigraphic architecture on hierarchical scales to understand geometries and textural variation of Grainstones as potential reservoir bodies. Hierarchical static 3-D geological models were generated that visualise the sedimentary architecture of primary reservoir bodies using industry standard 3-D geomodelling software.
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field scale geometries of upper khuff reservoir geobodies in an outcrop analogue oman mountains sultanate of oman
Petroleum Geoscience, 2011Co-Authors: Bastian Koehrer, Thomas Aigner, Michael PoppelreiterAbstract:ABSTRACT This paper provides data on the lateral continuity and geometry of potential reservoir geobodies in outcrops of Upper Khuff Formation time-equivalent strata in the Jebel Al Akhdar area (Oman Mountains, Sultanate of Oman). It presents outcrop-based quantitative data of shoal-associated Grainstone bodies in a sequence stratigraphic framework on the scale of an average Khuff gas field. Such data may be useful for correlation and modelling of subsurface reservoirs. A stratigraphic correlation of five outcrop sections, based on facies, sequence analysis and gamma-ray pattern, was used as a framework for mapping the distribution and lateral extent of Grainstone geobodies over an area of 8 × 8 km. Four Grainstone bodies were traced laterally along distinct marker beds over several hundreds of metres. The stratigraphic architecture shows a general layer-cake pattern. The thickness and lateral extent of reservoir geobodies is strongly influenced by their stratigraphic position. High-energy shoal facies developed preferentially in the regressive parts of cycles of multiple hierarchies. Individual Grainstone bodies may reach a thickness of 6 m, and those thicker than 3 m extend across the area of interest. Clinoforms or shingle-type geometries were explicitly searched for, but were not present. The observed systematic variations in extent and two-dimensional sedimentary architecture of Khuff Grainstone bodies were used as input for 3D static facies modelling. Outcomes of this study have been used to reduce uncertainty on Grainstone geometries, production-scale correlation strategies and definition of lateral facies successions in subsurface models of the Khuff reservoir.
