--> Abstract: Hydrocarbon Habitat of an Emerging Exploration Area, Deep Water Lower Congo Basin, Angola, by S. P. Edrich, A. B. Zuzek, E. J. Smart, S. O'Hara, A. B. Brayshaw, and S. J. Cawley; #90987 (1993).

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EDRICH, STEPHEN P., A. B. ZUZEK, E. J. SMART, S. O'HARA, A. B. BRAYSHAW, and S. J. CAWLEY, BP Exploration, Uxbridge, Middlesex, UK

ABSTRACT: Hydrocarbon Habitat of an Emerging Exploration Area, Deep Water Lower Congo Basin, Angola

Angola currently produces some 500,000 bopd from reservoirs of Cretaceous age under the present continental shelf. A largely undrilled Tertiary depocentre (maximum sediment thickness c. 5 km), lies predominantly under the deeper waters of the present day continental slope, offshore from the Congo River.

The principle play identified in this depocentre consists of Oligo-Miocene turbidite sand reservoirs, deposited in Basin Floor and Lower Slope environments. These overlie potentially rich source rocks of Early Cretaceous to Palaeogene age, known regionally on the West African Margin. Maturity modelling suggests that such sources, if present, will be in the oil window over much of the area. Structural style is dominated by extensional and salt tectonics, with fault blocks of Albian and younger sediments detaching on a regional decollement surface at the top of Aptian salt. A large number of dip and fault closed structural traps are mapped, with potential for additional stratigraphic traps.

The few shallow water tests of this stratigraphy have discovered several small hydrocarbon accumulations. Critical factors for success in the deepwater are: reservoir quality, the ability to produce at sustained high flow rates sufficient to justify commercial development; and the volumetric potential of the source rocks, sufficient to charge mapped structures. Reasonable models for oil generation and migration, together with the size and frequency of mapped structures, suggests that the Deep Water Lower Congo Basin could yield several billion barrels of oil discoveries in acreage recently awarded to a number of industry groups.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.