Preliminary Estimate of Undiscovered Petroleum Resources of Southern Africa

John Kingston

Onshore and offshore southern Africa (Nigeria and southward) are ten major rifted continental margin basins; six include about 100,000 mi² on the Atlantic coast, and five encompass about 300,000 mi² on the south and Indian Ocean side, including Madagascar. A series of four very large (totaling about 575,000 mi²) interior sag basins are found between South Africa and the central Congo.

The Atlantic margin basins are the most prospective and the only ones presently producing. Of these, the Niger delta is by far the most prolific, having original oil and gas reserves of some 25 billion BOE (barrels of oil equivalent) versus five billion BOE for the rest of the basinal trend.

The Indian Ocean marginal basins have more area and some shows, including a 22 billion BOE tar sand in Madagascar, but the lack of exploration success downgrades the prospects of this trend.

The interior sags have a large volume of sediment; about one-third is marine or lacustrine and probably thermally mature, but lack of established traps, or in some cases sufficient source rock, makes for high-risk prospects.

Preliminary most-likely estimates of undiscovered oil and gas resources are 15 billion BOE on the Atlantic margin, about 3 billion BOE on the Indian Ocean side, and about 1 billion BOE in the interior sags, with these latter basins having the highest potential for unknown giant fields.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.