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Seventh Arabian Plate Geology Workshop: Pre-Cambrian to Paleozoic Petroleum Systems in the Arabian Plate
- Conference date: December 9-13, 2018
- Location: Muscat, Oman
- Published: 09 December 2018
21 - 25 of 25 results
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Impact of Diagenetic Anhydrite on Reservoir Quality of the Khuff Formation, Greater Burgan Field in Kuwait
Authors S. Behbehani, M. Al-Ostath and A. AliAbstractThe Khuff Formation was deposited in shallow marine to tidal flat environments during Late Permian, directly after the Hercynian Orogeny. The porosity can classified into two categories: 1) Primary intergranular macroporosity of peloidal/ oolitic grainstone. 2) Secondary solution-enlarged porosity and jacked-open stylolite. The primary fabrics are completely dolomitized and replaced by subsequent anhydrite that dramatically reduce depositional porosity. Furthermore, vug- and fracture filling cementation of anhydrite occludes secondary porosity and close remnant pore spaces. There is no evidence of oil bearing from core data and reservoir quality is essentially negligible. Different types of anhydrite can be distinguished under a petrographic microscope including fine-grain “chicken-wire”, porphyrotopic, acicular-felted, lath-shaped, bladed and blocky anhydrite. Petrographic analysis determine that the precipitation of anhydrite coeval early diagenetic conditions related to evaporative concentrated waters in arid-region (e.g. environment enclosed lagoon or supratidal domain). However, Anhydrite also occur as precipitates of hydrothermal fluids after burial, showing association of stylolitic surfaces and pyrite nodules. It expected that the burial diagenesis cause migration and re-precipitation of anhydrite solutions into adjacent and up-dip strata. Therefore, this study suggests that the Khuff Formation away from crest part of Burgan field, where less fluid-rock interactions, provides better potential of hydrocarbon entrapment. This study present an example of destructive impact of burial diagenesis on world-class hydrocarbon province.
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Glaciers, flows, and fans: origins of a Neoproterozoic diamictite in the Saratoga Hills, Death Valley, California
Authors Saeed Tofaif, Daniel P. Le Heron, John Melvin and Thomas M. VandykAbstractThe Kingston Peak Formation (KPF) of Death Valley, California, provides an exceptional archive of Cryogenian glaciation and concomitant rifting of Rodinia. In the Saratoga Hills, an 800 m thick succession of diamictite-dominated strata is exposed, allowing lithofacies and clast compositions to be studied in detail, and for the relative influence of glacial versus slope processes on sedimentation to be critically assessed for the first time. Two detailed sections, 400 m apart, allow four facies associations (FA) to be established: (1) Thinly Laminated Argillaceous Sandstone (interpreted as low density turbidites) (2) Laminated, Deformed, and Brecciated Limestone (interpreted as carbonate sourced turbidites truncated by fault-controlled debris flow marking the onset of glaciation) (3) Bedded Massive Diamictite (interpreted as glacially-fed debris flow deposits) (4) Interbedded Mudstone, Sandstone, and Diamictite (interpreted as stratified diamictite deposited via ice rafted debris and passing gradually into turbidites punctuated by heavily deformed intervals). Bedded massive diamictite (FA 3) is dominant in the succession and shows a gradual up section transition into interbedded mudstone, sandstone, and diamictite (FA 4). This is interpreted to record a waning glacial influence (from glacially sourced debris flow to stratified diamictite strongly influenced by ice rafted debris) and a waxing tectonic influence upsection. Clasts in the diamictite include carbonate, siliciclastic intraclasts, granite, diabase, gneiss, and quartzite. Clast presence profiles suggest that in spite of the comparable along-strike facies profiles between the two logs, clast content is of little use in aiding correlation and lithostratigraphic subdivision of the Kingston Peak Formation. Thus, local source areas and a complex drainage network are envisaged. The stacking pattern of the lithofacies, complex drainage network reflected in the variation of clast-composition, and localized deformation features of FA4 all support the deposition as part of a trough mouth fan system.
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