Uncertainty in reservoir prediction: Example of shelf edge delta field

Conference · Wed Sep 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:7135496

Durand, J; Lecanu, H ^[1]; Drullion, G ^[2]

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1. Elf Aquitaine Production, Pau (France)
2. Elf Enterprise Caledonia, Aberdeen (United Kingdom)

Four wells have been drilled to appraise an oil field occurring in middle to upper Miocene sandstones of the eastern offshore Niger Delta. Because the reservoir thickness is below seismic resolution, the reservoir model is based on cores, high-resolution dipmeter tools, and conventional wireline logs. The model developed with the first three wells consists of dip-oriented elongate marine sandbodies occurring in an estuary mouth that were identified from cores and microresistivity response. They are interpreted to be located in the outer zone of the estuary dominated by tidal processes. Foreset dip azimuths measured from the Formation Micro Scanner suggest straight-crested bed forms and show that sand transport was dominantly to the west and northwest. This direction is interpreted to be the net export direction of the deltaic distributary system to the sea. The tidal mouth bars are stacked in seaward-stepping or landward-stepping patterns and are time transgressive. The reservoir was expected to progressively disappear westward. Facies revealed in cores from the fourth well drilled in a westward direction differ from the model proposed above. Vertically dipping beds are overlapped by normal-dipping tidal sandbars interbedded with gravity flow facies. Dipmeter study and facies characteristics suggest an olistolitic block progressively overlain by deltaic progradation due to the destabilization of the delta front in an extensional stress regime. On seismic profiles, a major listric normal fault associated with roll-over structure confirms this upgraded reservoir interpretation.

• OSTI ID: 7135496
• Report Number(s): CONF-9310237-; CODEN: AABUD2
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:9; Conference: American Association of Petroleum Geologists (AAPG) mid-continent section meeting, Amarillo, TX (United States), 10-12 Oct 1993; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
GEOLOGIC MODELS
RELIABILITY
RESERVOIR ROCK
FORECASTING
SANDSTONES
ESTUARIES
EXPLORATORY WELLS
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
NIGER
OIL FIELDS
PETROLEUM DEPOSITS
AFRICA
DEVELOPING COUNTRIES
GEOLOGIC DEPOSITS
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MINERAL RESOURCES
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SURFACE WATERS
WELLS
020200* - Petroleum- Reserves
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