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Площадь: 290236.6 км²
Tanzania basin
Compared with prolonged exploration history and gigantic discoveries in North Africa and West Africa, East Africa deepwater areas experienced breakthroughs only in the past few years with discoveries of a number of world-class deepwater gas fields in Rovuma, Tanzania and some other basins.
East Africa passive continental margin refers to shore lines of East Africa south of Somalia. It includes 7 basins: Somalia, Ramu, Tanzania, Rovuma, Zambezi Delta, Morondava and Majunga (Fig. 1). Drilling and exploration operations along coastal lines of East Africa started in 1958. Up to 2010, only 7 medium- or small-sized gas fields with commercial values had been found in on-shore and shallow-water zones. Since August 2010, exploration operations switched into deepwater and ultra-deep waters. Up until the end of 2014, 36 medium- or large-sized gas fields, including 9 deepwater major gas fields, had been found in the Rovuma Basin and the Tanzania Basin (Fig. 2, Table 1). With success rates over 80% for exploration wells, East Africa is currently a hot spot for natural gas exploration in the world.
Fig. 1. Distribution of basins and deepwater gas fields in East Africa (according to Ref.).
Table 1. Deepwater giant gas fields in East Africa.
Fig. 2. Geological section of Rovuma basin in East Africa.
The East African passive continental margin basins contain 3 packages of hydrocarbon source rocks: Upper Carboniferous–Lower Jurassic continental shale and coal measures, Middle-Upper Jurassic–Cretaceous marine shale, and Paleogene–Neogene continental shelf–slope shale. Middle-Upper Jurassic–Cretaceous marine shale can be seen as the dominant hydrocarbon source rocks of shore basins in East Africa. The Permian–Neogene formations often contain multiple reservoirs dominated by delta sandstone and deep-sea turbidite sandstone, distributed mostly in the Rovuma Basin and Tanzania Basin. Cap rocks are predominantly marine shale with thick evaporite developed regionally. Majority of traps are structural traps with hydrocarbons migrating along faults to form reservoirs.
Currently, all of the discoveries in deepwater areas of East Africa are distributed in the northern Rovuma Delta Basin and slopes of the Tanzania Basin. With a low overall exploration degree, deepwater areas may present great potential for future exploration operations.
Data source: Giant discoveries of oil and gas fields in global deepwaters in the past 40 years and the prospect of exploration. Gongcheng Zhang, Hongjun Qu, Guojun Chen, Chong Zhao, Fenglian Zhang, Haizhang Yang, Zhao Zhao, Ming Ma. 2019
Следующий Бассейн: Cyrenaica