Geology and Petroleum Resources of Central and East-Central Africa
James A. Peterson
The petroleum provinces of central and east-central Africa include the Somali basin, the Ethiopian plateau and rift belt, and the central African rift basins. The western shelf on the Somali basin in the "horn of Africa" contains a sedimentary cover 1,000-10,000 m (3,000-3,500 ft) thick of Mesozoic and Tertiary marine and continental clastic, carbonate, and evaporite deposits with good reservoir and potentially adequate source rock properties. To date, no commercial oil or gas discoveries have been made. The Ethiopian plateau and rift belt is a high-risk area with minimum potential for commercial petroleum because the Neogene rifting origin of the province has resulted in high geothermal gradients, extensive volcanism, and inadequate marine deposits and petroleum source rocks. The cen ral Africa interior basins are continental craton-rifted depressions of Late Cretaceous and Tertiary age containing as much as 4,000 m (13,000 ft) or more of fluvial and lacustrine clastic beds, which intertongue with nearshore marine clastic and carbonate beds in the western basins. Since the mid-1970s, approximately 13 oil discoveries have been made in the Upper Nile, Doba-Doseo, and Chad basins. These basins produce from fluvial and lacustrine sandstone reservoirs, sourced by lacustrine organic shale beds of Cretaceous age. The Benue trough is a rifted depression of middle Cretaceous age adjoined on the southwest by the prolific Niger Delta petroleum province. The trough is filled with 6,000 m (20,000 ft) or more of clastic and carbonate marine and continental rocks of late Early Cret ceous and early Cenozoic age. Very few exploratory wells have been drilled, and no commercial discoveries have been made although good reservoir and source rocks are present.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.