The Akaso field, Nigeria: Use of integrated 3-D seismic/fault slicing/clay shearing on fault trapping and dynamic leakage

Conference · Fri Mar 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5803016

Jev, B I; Kaars-Sijpestein, C H; Wilkie, J T ^[1]; Peters, M P.M.A. ^[2]

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1. Shell Petroleum Development Co. Ltd., Lagos (Nigeria)
2. Kon. Shell E and P Lab., Rijswijk (Netherlands)

The Akaso field on the Eastern Niger delta (STOIIP 401 MMstb) is separated from the large Cawthorne Channel field (STOIIP 1307 MMstb) by a major antithetic fault. In 1989 3-D seismic data revealed a subtle back-split off this antithetic to the west of the main Akaso field, behind which stacked amplitude anomalies occurred extending to the tip line of the back-split. Fault slicing and clay smear studies of the back-split and main antithetic indicated strong seal potential with occasional leak windows. These results were fully confirmed by a deviated appraisal well in late 1989 that found 183 MMstb STOIIP in a series of stacked footwall closures. The trapping potential of this fault can be contrasted with its behavior during depletion based upon RFT data acquired in a series of Akaso development wells in 1990. Depletion of the Akaso E and G sands was observed due to production from the juxtaposed C-D and E sands of Cawthorne Channel and subsequent fault breakdown. Dynamic pressure drops of 120 psi and 311 psi observed in the Akaso field therefore represent a prime example of the trapping potential of clay-smeared faults and their subsequent leakage during differential depletion.

• OSTI ID: 5803016
• Report Number(s): CONF-910403--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
AFRICA
ANTICLINES
DEVELOPING COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
GEOPHYSICAL SURVEYS
LEAKS
MINERAL RESOURCES
NIGERIA
PETROLEUM DEPOSITS
RESOURCES
SEISMIC SURVEYS
SURVEYS
THREE-DIMENSIONAL CALCULATIONS