TECTONO-SEDIMENTARY EVOLUTION AND PETROLEUM POTENTIAL OF NAMIBE BASIN AT THE PASSIVE CONTINENTAL MARGIN OF WEST AFRICA

The Namibe Basin lies on the passive continental margin of West Africa, which is a specific large basin in the world without oil and gas exploration activities so far. Based on collected materials on basic regional geology and hydrocarbon geology from adjacent basins, using integrated petroleum geological approaches, the potentials of oil and gas in the basin are studied in this paper. The study shows that the Namibe basin has experienced four tectono-sedimentary evolution stages: pre-rift stage (P-J₂), rift stage (J₃-K₁ Barremian), transitional stage (K₁ Aptian) and passive continental margin stage (K₁ late Aptian- nowadays). There are 3 sets of source rocks, predominated by the early Cretaceous Barem lacustrine shale; There occur 3 sets of reservoirs in late rift, early drift and late drift stages respectively. The thick transitional sequence of Lower Cretaceous Aptian shale is an effective regional cap rock, in addition to several local caprocks in the Late Cretaceous-Cenozoic drift sequence. Structural and stratigraphic traps dominate the basin. Faults and unconformity boundaries are the main paths for migration. There occur two possible source-reservoir-cap assemblages in the Lower Cretaceous and Upper Cretaceous-Oligocene-Miocene respectively, with great oil and gas exploration prospect.