Tengiz oil field, Kazakstan: A carbonate platform and supergiant field
- Chevron Overseas Petroleum, Inc., San Ramon, CA (United States)
- Chevron USA, Midland, TX (United States)
The Tengiz oil field was discovered in 1979 on the northeastern shore of the Caspian Sea in western Kazakstan. The Carboniferous and Devonian age carbonate reservoir is more than 2000 in, thick, 270 km[sup 2] in area extent and buried to a depth of 4000 m (13,120 ft.). The oil column exceeds 1450 m in length and is highly overpressured. The Tengiz reservoir resembles a modem day constructional-type carbonate platform in size, shape and lithofacies. The top of the platform is relatively flat, except for structural highs along the northern, eastern and southern platform margins that developed during post-depositional down-faulting of the platform interior. The platform edge is a depositional escarpment along which subsequent faulting has occurred. Debris-slope conglomerates, shed off the platform during growth, surround the platform escarpment. Bashkirian age ootitic, crinoidal, algal grainstones comprise the upper 100 m of the platform and overlie 350 m of Serpukhovian and Okskian age brachiopodal, crinoidal, algal packstones. Lithofacies are a really widespread and show little variation in composition and stratigraphic thickness across the entire platform. Depositional cycle thicknesses are less than 5 meters for the Bashkirian grainstones and up to 30 meters for the Serpukhovian/Oksky packstones. Lagoonal and reefal lithofacies have not been identified in core to date. Porosity is highly variable and includes interparticle, moldic, channel, vuggy and fracture pore types. Solid bitumen is present in much of the pore space. Secondary porosity formed both before and after bitumen precipitation. Production logs and core data reveal that zones with secondary porosity provide fluid entry into the wellbore.
- OSTI ID:
- 6591243
- Report Number(s):
- CONF-960527-; CODEN: AABUD2
- Journal Information:
- AAPG Bulletin, Vol. 5; Conference: Annual convention of the American Association of Petroleum Geologists, Inc. and the Society for Sedimentary Geology: global exploration and geotechnology, San Diego, CA (United States), 19-22 May 1996; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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