Deep-Water Hydrocarbon Exploration Potential in the Offshore Northwest Africa

Abstract

By the end of 2016, more than 70 major sedimentary basins are identified to host deep-water petroleum accumulations throughout the world. The total deep-water recoverable reserves are 261 billion barrels of oil equivalent, with the passive margin basins accounting for 90%. Offshore northwest Africa has been the most attractive deep-water hydrocarbon area, recently. Many giant oil and gas fields have been discovered in this area so far, including Sne, Fan, Tortue and Teranga fields. This study is designated to reveal hydrocarbon accumulation characteristics and distribution patterns of passive continental margins in the deep-water offshore northwest Africa by an integrated analysis of basin geology, regional geology, petroleum system and play. The formation and evolution of these passive margin basins are closely related to the opening of the Central Atlantic Ocean that separated North America from the Africa. Three total petroleum systems are recognized, including the Cretaceous petroleum system in the Senegal Basin, the Jurassic-Jurassic/Cretaceous petroleum system in Aaiun-Tarfaya Basin and the Oxfordian-Oxfordian petroleum system in Essaouira Basin, and the Cretaceous petroleum system is of great significance. There are four main plays, including the Jurassic/Lower Cretaceous stratigraphic-structural play, the Lower Cretaceous stratigraphic play, the Upper Cretaceous stratigraphic-structural play and the Miocene structural play. The results show that there are three hydrocarbon accumulation models in the deep-water offshore northwest Africa, namely the lower source and upper reservoir, vertical migration-accumulation model in the Miocene turbidite, the lateral migration-accumulation model in the Cenomanian-Albian turbidite and the lateral migration-accumulation model in the Albian delta-unconformity sandstone. Under the influence of the global sea level eustacy, depositional environment and provenance supply, the Cretaceous clastic rocks deposited in turbidite channels and slope fans can serve good reservoirs in addition to the Jurassic carbonates. The main exploration targets and exploration direction in the future should focus on the Jurassic carbonates and turbidite stratigraphic-structure trap, the Cretaceous turbidite stratigraphic-structure trap and the post-salt Upper Miocene turbidite structural trap.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018