Petroleum reservoir

About: Petroleum reservoir is a research topic. Over the lifetime, 5403 publications have been published within this topic receiving 83535 citations. The topic is also known as: petroleum deposit.

CO2 Injection Effect on Geomechanical and Flow Properties of Calcite-Rich Reservoirs

Abstract: Geologic carbon storage is considered as a requisite to effectively mitigate climate change, so large amounts of carbon dioxide (CO2) are expected to be injected in sedimentary saline formations CO2 injection leads to the creation of acidic solution when it dissolves into the resident brine, which can react with reservoir rock, especially carbonates We numerically investigated the behavior of reservoir-caprock system where CO2 injection-induced changes in the hydraulic and geomechanical properties of Apulian limestone were measured in the laboratory We found that porosity of the limestone slightly decreases after CO2 treatment, which lead to a permeability reduction by a factor of two In the treated specimens, calcite dissolution was observed at the inlet, but carbonate precipitation occurred at the outlet, which was closed during the reaction time of three days Additionally, the relative permeability curves were modified after CO2–rock interaction, especially the one for water, which evolved from a quadratic to a quasi-linear function of the water saturation degree Geomechanically, the limestone became softer and it was weakened after being altered by CO2 Simulation results showed that the property changes occurring within the CO2 plume caused a stress redistribution because CO2 treated limestone became softer and tended to deform more in response to pressure buildup than the pristine rock The reduction in strength induced by geochemical reactions may eventually cause shear failure within the CO2 plume affected rock This combination of laboratory experiments with numerical simulations leads to a better understanding of the implications of coupled chemo-mechanical interactions in geologic carbon storage

Mississippian Sedimentation and Oil Fields in Southeastern Saskatchewan: Carboniferous

Abstract: Marked facies changes occur in the Mission Canyon and lower part of the Charles formation (Mississippian) in southeastern Saskatchewan. Northeastward from the basinal area, four successive environments of deposition with characteristic rock types and fossils may be mapped as follows. 1. Basin--dark brown-gray argillaceous limestone containing scattered white crinoid columnals, black bituminous shale partings, and brownish gray chert. 2. Open marine shelf--cream-white fossiliferous-fragmental and chalky limestones containing crinoids, bryozoans, brachiopods, and zaphrentid corals. 3. Barrier bank--cream-white precipitated limestones including pisolitic, oolitic, pseudo-oolitic, and lithographic types. Fossils include abundant algae and few scattered gastropods. 4. Lagoon--cream-white chalky argillaceous limestone containing ostracods, earthy to sucrosic secondary dolomite and anhydrite. Evaporitic (primary?) dolomites occur in the upper Charles as a result of basin-wide evaporitic conditions. These typically dense (cryptocrystalline) and non-porous dolomites are closely associated with anhydrite. Factors which control porosity in the limestones include sorting of fossil debris or precipitated calcareous grains, submarine erosion and re-deposition of partially lithified calcareous muds, solution, dolomitization?, fractures, compaction, and infilling of pores by calcite, anhydrite, or chert. Stratigraphic trap oil accumulations occur where permeable units of the Mission Canyon and Charles are truncated and overlain by pre-middle Jurassic red beds. Factors affecting oil accumulation include the presence of the following. a. Permeable reservoir beds at or near the unconformity. b. Anhydrite filling pores where the permeable reservoir beds are truncated by the pre-Jurassic erosion. c. Anhydrite beds conformably overlying and underlying the permeable units and thus form a roof and floor for the reservoir beds. d. Topography of the Mississippian erosion surface. Mississippian strata in the oil-producing area of southeastern Saskatchewan are characterized by the following. 1. Relatively steep dips (40-60 feet per mile) as compared with dips of 10-20 feet per mile in much of southwestern Saskatchewan. 2. Relatively rapid truncation (15-40 feet per mile) as compared with an average of approximately 5 feet per mile in southwestern Saskatchewan. 3. Relatively saline waters (50,000-150,000 parts per million of chloride-ion content) as compared with 100-8,000 parts per million in southwestern Saskatchewan. In exploration for new trends or extensions of known producing areas, important consideration should be given to the distribution of permeable rock facies within individual stratigraphic units. In addition, it is possible to predict the location of topographically high trends as the various lithoogic types are differentially resistant to erosion. For example, the precipitated barrier bank limestones End_Page 331------------------------ are relatively resistant to weathering and form topographic ridges in the Nottingham field. The lower limit of oil accumulation within reservoir beds may be determined by the location of a spill point, in turn controlled by the down-dip limit of lagoonal anhydrite floors.

Stratigraphy and sedimentation of the Unayzah reservoir, central Saudi Arabia

Abstract: Significant reserves of Arabian super light oil, condensate, and associated gas occur in the various genetically different sandstone bodies of the upper Permian Unayzah and Khuff Formations in Central Saudi Arabia. The Unayzah Formation which rests unconformably on the older formations is composed of red colored, poorly sorted conglomerate, sandstone, siltstone, mudstone, caliche and nodular anhydrite. Facies changes occur due to the presence of various subenvironments and possible faulting and structural growth in the basin during deposition. However, the entire Unayzah Formation shows an overall fining and thinning-upward sequence. It was deposited as coalescing alluvial fans dominated by braided streams which graded into meandering stream and playa lakes under and to semi-arid conditions. Eolian processes were also inferred. A marked unconformity which is indicated by the occurrence of thick caliche and soil horizons separate the Unayzah and the overlying Khuff Formation. The Khuff Formation consists primarily of marine shale, marl, and fine- to very coarse-grained sandstones in the lower parts; shale, limestone, dolomite, and amhydrite in the upper parts. The sandstones were deposited as incised channel fills and their associated low stand deltaic sediments as a result of fluctuating sea level during the deposition of the Khuff Formation. The basemore » of the incised channels represent a sequence boundary. Red colored and rooted paleosols were formed on the underlying marine sediments. During relative sea level rise, good quality reservoir sands were deposited by aggradation within the incised channels. Sand deposition within the channels terminated at the same time, and the area was covered by shallow marine limestones, shales and marls during maximum sea level highstand. Although the Unayzah reservoir occurs in both the Unayzah and the Khuff Formations because of their different geometry, continuity, and reservoir quality, they have been studied separately.« less