DIFFERENCE OF HYDROCARBON ACCUMULATION CONDITIONS IN SENEGAL BASIN IN WEST AFRICA

Tectonic study suggests that the evolution of Mid-Atlantic controls the formation of Senegal Basin. Once it was formed, the basin has experienced three stages of evolution: rifting stage, transitional stage and drifting stage. Under the Control of differentiation of tectonic and sedimentation in the transitional and drifting stages, the basin was separated into two parts, the southern sub-basin and the northern sub-basin. The southern sub-basin is characterized by a "wide shelf and steep slope", while the north sub-basin is opposite and characterized by a "narrow shelf and gentle slope". Cenomanian-Turonian and Aptian-Albian marine source rocks are well developed in the drifting stage, and the thermal evolution of source rock is in a pattern of "high north and low south". There are a variety of favorable sedimentary reservoirs in the basin. The structure of the basin controls the distribution of sediments. The southern sub-basin is dominated by continental shelf deltaic sandstone and turbidite fan sandstone, whereas the northern sub-basin is mainly composed of turbidite channels and turbidite fan sandstones. Three types of hydrocarbon accumulations are found available in the basin. The northern sub-basin is dominated by the accumulations of "self-generated and self-accumulated near-source hydrocarbon" and the type of "later accumulation of early generated hydrocarbon through salt-related fault migration", while southern sub-basin is characterized by oil and gas "generated in-situ and accumulated laterally with faults and unconformities as migration paths" and the type of "self-generated and accumulated hydrocarbon in near-source storages".