Mafia deep basin: basin development and petroleum system elements

This study aimed to assess basin development and petroleum system elements of the Mafia deep basin based on the interpretation of 2D seismic data. The results have shown that the development of the Mafia deep basin was influenced by several tectonic episodes, including the Permo-Triassic Karoo rifting, the Mid-Jurassic–Cretaceous tectonic event, and the Cenozoic extensional and strike-slip faulting tectonics. The tectonic events created different structures that allowed the migration and trapping of hydrocarbons in the study area. These structures include deep-rooted faults and both negative and positive flowering fault structures. The positive flower structures along the Seagap Fault form potential petroleum prospects in the Mafia deep basin. Petroleum migration took advantage of weak zones below sand-filled channels and open fault systems linked to episodic tectonic reactivations. Potential petroleum reservoirs include the Middle Jurassic shallow water deposits, the Cretaceous hybrid turbidite-contourite deposits, Paleocene–Miocene southward migrating channelized sands, and the Pliocene–Holocene channel deposits and their respective channel-levee successions. These reservoirs are interpreted to have been charged by the deep-water Middle Jurassic source rocks. The possible presence of gas generation, migration, and accumulation in the Mafia deep basin is interpreted based on the presence of direct hydrocarbon indicators. These indicators include gas chimneys and wipe-outs, and flat spots that are mostly available in the Paleocene–Holocene stratigraphy of the study area. Potential seal rocks include extensive drift deposits and deep-water shales deposited during marine transgressions.