--> Tectonic Evolution and Hydrocarbon Distribution of Basins in Africa

2018 AAPG International Conference and Exhibition

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Tectonic Evolution and Hydrocarbon Distribution of Basins in Africa

Abstract

African sedimentary basins, with relatively low degree of exploration and huge undiscovered hydrocarbon reserve, are the present hot spots for oil and gas exploration. The African plate mainly experienced three tectonic evolution stages during Phanerozoic, during which the forming, drifting and breaking up of the Gondwanaland led to the development of several types of African basins. Based on our basin study of tectonic evolution and prototype and petroleum geological analysis, the structural characteristics and rules of hydrocarbon accumulation in different types of rifts are determined as follows. The pericratonic basins in north Africa initiated in the early Paleozoic, in which hydrocarbons mainly distributed in the huge dome structures, formed under the compression of the Hercynian movement, and the Paleozoic petroleum system dominated in the pericratonic basins. The continental margin rift basins in north Africa experienced rifting and subsidence after the Hercynian movement, and the differences in subsidence intensity and depocenter led to diversity in hydrocarbon accumulation and resource potential. The passive margin rift basins in the east and west Africa formed during the Pangea paleo-plate breakup and Atlantic and Indian Ocean rifting: In the west, saliferous formations are widely distributed with two petroleum systems developed above and below the saline formations, respectively; in the east, hydrocarbon distribution is heterogenous and controlled primarily by the structural architectures of the basins. The intra-plate central and west Africa rift basins experienced three periods of rifting, i.e, the early Cretaceous, late Cretaceous and Paleogene. The E-W striking basins were uplifted intensely under compression from the collision of the African and Eurasian Plates in the late Cretaceous; as a result, hydrocarbons accumulated primarily in the lower Cretaceous. The NW-SE striking basins, slightly affected by the collision, have hydrocarbon distributions mainly in the upper Cretaceous-Paleogene. Finally, the eastern African rift basins and the Red Sea basin are newly formed Cenozoic basins with dominant Cenozoic petroleum system. The hydrocarbon in the Cenozoic delta basins is controlled by fan delta sand body distribution and basin architecture.