Hydrocarbon in the Majunga Basin in East Africa: geological characteristics and zonation evaluation

In recent years, the continuous discovery of large gas fields along the East African continental margin has attracted widespread attention from oil companies in the world. The Majunga Basin, as one of the least explored basins in the East African region, the outcomes of oil and gas exploration are few. Based on the international commercial oil and gas field databases IHS and Tellus, we reviewed the oil and gas exploration history, regional structural sedimentary evolution, and characteristics of the hydrocarbon accumulation elements of the basin. The research results indicate that the Majunga Basin is a Mesozoic-Cenozoic passive continental margin basin superimposed on the Late Paleozoic-Jurassic rift, having experienced three evolutionary stages: syn-rift, Madagascar block breakup, and passive continental margin, forming a sedimentary sequence that transitions from terrestrial in the east to marine in the west. To date, no commercial oil and gas discoveries have been made in the basin, and the potential hydrocarbon accumulation combinations include the Cretaceous structural-stratigraphic and Triassic-Jurassic Sakamena/Isalo Formation structural combinations. Using hydrocarbon-bearing zone evaluation methods commonly applied in China, five oil and gas prospective zones, including the western deepwater zone of the basin, have been delineated. The comprehensive evaluation showed that the western deepwater zone is the most favorable zone, and we recommended that the next step should strengthen the deployment of seismic work to confirm the location of favorable traps.