Microfacies, depositional environment and diagenetic evolution controls on the reservoir quality of the Permian Upper Dalan Formation, Kish Gas Field, Zagros Basin

ABSTRACT Sandstones of the Early Paleozoic Miqrat Formation and Barik Sandstone Member (Haima Supergroup) are the most prolific gas/condensate containing units in the northern part of the Interior Oman Sedimentary Basin (IOSB). The reservoir-quality of these sandstones, buried to depths exceeding 5 km, is critically related to the depositional environment, burial-related diagenetic reactions, the timing of liquid hydrocarbon charge and the replacement of liquid hydrocarbon by gas/condensate. The depositional environment of the sandstones controls the net-sand distribution which results in poorer reservoir properties northwards parallel to the axis of the Ghaba Salt Basin. The sandy delta deposits of the Barik Sandstone Member have a complex diagenetic history, with early dolomite cementation, followed by compaction, chlorite formation, hydrocarbon charge, quartz and anhydrite precipitation and the formation of pore-filling and pore-lining bitumen. In the Miqrat Formation sandstone, which is comprised of inland sabkha deposits, similar authigenic minerals occur, but with higher abundances of dolomite and anhydrite, and less quartz cement. The deduced pore water evolution from deposition to recent, in both the Miqrat Formation and the Barik Sandstone Member, reflects an early addition of saline continental waters and hydrocarbon-burial related mineral reactions with the likely influx of lower-saline waters during the obduction of the Oman Mountains. Four structural provinces are recognized in the IOSB based on regional differences in the subsidence/uplift history: the Eastern Flank, the Ghaba and Fahud Salt Basins and the Mabrouk-Makarem High. In the Fahud Salt Basin, biodegradation of an early oil charge during Late Paleozoic uplift resulted in reservoir-quality degradation by bitumen clogging of the pore space. On the Eastern Flank and the Mabrouk-Makarem High, however, the early oil bypassed the area. In contrast, post-Carboniferous liquid hydrocarbons were trapped in the Mabrouk-Makarem High, whereas on the Eastern Flank surface water infiltration and loss of hydrocarbons or biodegradation to pore occluding bitumen occurred. In the Ghaba Salt Basin, post-Carboniferous hydrocarbon charge induced a redox reaction to form porosity/permeability preserving chlorite in the reservoirs. The liquid hydrocarbons were replaced since the obduction of the Oman Mountains by gas/condensate which prevented the deep parts (>5,000 m) of the Ghaba Salt Basin from pore occluding pyrobitumen and thus deterioration of the reservoir quality.

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Diagenetic controlled reservoir quality of South Pars gas field, an integrated approach

Comptes Rendus Geoscience ◽

10.1016/j.crte.2010.10.004 ◽

2011 ◽

Vol 343 (1) ◽

pp. 55-71 ◽

Cited By ~ 66

Author(s):

Vahid Tavakoli ◽

Hossain Rahimpour-Bonab ◽

Behrooz Esrafili-Dizaji

Keyword(s):

Integrated Approach ◽

Reservoir Quality ◽

Gas Field

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The Cavendish Field, Block 43/19, UK North Sea

Geological Society London Memoirs ◽

10.1144/m52-2019-10 ◽

2020 ◽

Vol 52 (1) ◽

pp. 131-141 ◽

Cited By ~ 2

Author(s):

N. Wasielka ◽

J. G. Gluyas ◽

H. Breese ◽

R. Symonds

Keyword(s):

Grain Size ◽

Continental Shelf ◽

North Sea ◽

Water Depth ◽

Reservoir Quality ◽

Low Permeability ◽

Gas Field ◽

Upper Carboniferous ◽

Northern Margin

AbstractThe Cavendish Field is located in UK Continental Shelf Block 43/19a on the northern margin of the Outer Silverpit Basin of the Southern North Sea, 87 miles (140 km) NE of the Lincolnshire coast in a water depth of 62 ft (18.9 m). The Cavendish Field is a gas field in the upper Carboniferous Namurian C (Millstone Grit Formation) and Westphalian A (Caister Coal Formation) strata. It was discovered in 1989 by Britoil-operated well 43/19-1. Production started in 2007 and ceased in 2018. Gas initially in place was 184 bcf and at end of field life 98 bcf had been produced. The field was developed by three wells drilled through the normally unmanned platform into fluvio-deltaic sandstone intervals that had sufficiently good reservoir quality to be effective reservoirs. The majority of the formation within closure comprises mudstones, siltstones and low permeability, non-reservoir-quality feldspathic sandstones. The quality of the reservoir is variable and is controlled by grain size, feldspar content and diagenesis. The field is a structural trap, sealed by a combination of intra-Carboniferous mudstones and a thick sequence of Permian mudstones and evaporites.

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Reservoir Quality of Upper Jurassic Corallian Sandstones, Weald Basin, UK

Geosciences ◽

10.3390/geosciences11110446 ◽

2021 ◽

Vol 11 (11) ◽

pp. 446

Author(s):

Dinfa Vincent Barshep ◽

Richard Henry Worden

Keyword(s):

Carbon Capture ◽

Carbon Capture And Storage ◽

Upper Jurassic ◽

Reservoir Quality ◽

Main Process ◽

Shallow Marine ◽

Porosity And Permeability ◽

Calcite Cement ◽

Diagenetic Evolution

The Upper Jurassic, shallow marine Corallian sandstones of the Weald Basin, UK, are significant onshore reservoirs due to their future potential for carbon capture and storage (CCS) and hydrogen storage. These reservoir rocks, buried to no deeper than 1700 m before uplift to 850 to 900 m at the present time, also provide an opportunity to study the pivotal role of shallow marine sandstone eodiagenesis. With little evidence of compaction, these rocks show low to moderate porosity for their relatively shallow burial depths. Their porosity ranges from 0.8 to 30% with an average of 12.6% and permeability range from 0.01 to 887 mD with an average of 31 mD. The Corallian sandstones of the Weald Basin are relatively poorly studied; consequently, there is a paucity of data on their reservoir quality which limits any ability to predict porosity and permeability away from wells. This study presents a potential first in the examination of diagenetic controls of reservoir quality of the Corallian sandstones, of the Weald Basin’s Palmers Wood and Bletchingley oil fields, using a combination of core analysis, sedimentary core logs, petrography, wireline analysis, SEM-EDS analysis and geochemical analysis to understand the extent of diagenetic evolution of the sandstones and its effects on reservoir quality. The analyses show a dominant quartz arenite lithology with minor feldspars, bioclasts, Fe-ooids and extra-basinal lithic grains. We conclude that little compactional porosity-loss occurred with cementation being the main process that caused porosity-loss. Early calcite cement, from neomorphism of contemporaneously deposited bioclasts, represents the majority of the early cement, which subsequently prevented mechanical compaction. Calcite cement is also interpreted to have formed during burial from decarboxylation-derived CO2 during source rock maturation. Other cements include the Fe-clay berthierine, apatite, pyrite, dolomite, siderite, quartz, illite and kaolinite. Reservoir quality in the Corallian sandstones show no significant depositional textural controls; it was reduced by dominant calcite cementation, locally preserved by berthierine grain coats that inhibited quartz cement and enhanced by detrital grain dissolution as well as cement dissolution. Reservoir quality in the Corallian sandstones can therefore be predicted by considering abundance of calcite cement from bioclasts, organically derived CO2 and Fe-clay coats.

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Alkaline Diagenesis and Reservoir Quality of the Upper Paleozoic Tight Sandstones in Daniudi Gas Field, China

10.3997/2214-4609.201900856 ◽

2019 ◽

Author(s):

X. Chen ◽

S. Xu ◽

X. Qu ◽

L. Qiu ◽

Y. Liu

Keyword(s):

Reservoir Quality ◽

Gas Field ◽

Upper Paleozoic

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Ordovician deep dolomite reservoirs in the intracratonic Ordos Basin, China: Depositional model and Diagenetic evolution

Energy Exploration & Exploitation ◽

10.1177/0144598718778171 ◽

2018 ◽

Vol 36 (4) ◽

pp. 850-871 ◽

Cited By ~ 6

Author(s):

Anqing Chen ◽

Shenglin Xu ◽

Shuai Yang ◽

Hongde Chen ◽

Zhongtang Su ◽

...

Keyword(s):

Tidal Flat ◽

Depositional Environment ◽

Ordos Basin ◽

Depositional Model ◽

Facies Associations ◽

Intracratonic Basins ◽

Sea Level Fluctuation ◽

Reservoir Type ◽

Diagenetic Evolution

Recent natural gas discoveries indicate that non-karstification-dominated reservoirs exist in the intracratonic Ordos Basin. This study examines the sedimentological and geochemical characteristics needed to clarify the depositional model and diagenetic evolution process of this newly discovered reservoir type. The depositional environment of the dolomite reservoir can be characterized as a tidal flat that grew from the Central Paleo-uplift to the eastern depression by cyclic progradation on an epeiric platform. A tidal flat sequence can extend laterally as a progradational wedge in each cycle of sea level fluctuation. The sheet-shaped peritidal shoal facies associations patched on the wedge represent potential dolomite reservoirs and can be recognized by the presence of doloarenite that has been altered into a vaguely relict grained-texture by diagenesis. Although continuing destructive diagenesis has led to reservoir densification, burial dolomitization and burial dissolution with facies selectivity have tended to occur in peritidal shoal facies associations, thus improving the quality of the dolomite reservoirs. These models provide new insights for targeting deep dolomite hydrocarbon reservoirs in intracratonic basins.

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