| This study focused on the process of regional tectonic evolution,basin structural style,petroleum geological conditions and hydrocarbon accumulation characteristics in the East African rift system(EARS).Based on this,this paper summarizes the hydrocarbon accumulation features and optimize the favorable exploration area.The results show that:(1)The EARS is affected by multiple tectonic movements in different time and space environment.Under the effect of multiple rift activities,the EARS can be further divided into three stuctural units:the northern section of the Western Branch,the middle-south section of the Western Branch and the Eastern Branch.The trend and distribution of rifts are controlled by craton and mantle plume.The rifts are filled by river-(fan)delta-lacustrine sedimentary system.(2)A variety of extensional structural combinations are formed in the EARS.The basins are mostly connected by structural adjustment zones,which have important effect on the development of sedimentary strata and petroleum accumulation.Multiple structure styles are developed in the basins,which provide favorable places for hydrocarbon accumulation.(3)The source rocks in the EARS are mainly organic rich shale distributed in the Karoo Group,Eocene-Middle Miocene and Upper Miocene-lower Pliocene.The reservoirs are sandstone distributed in Carboniferous-Permian,Jurassic-Cretaceous and Paleogene-Neogene.The shale interbeds form important local caps and Neogene thick shales are regional caps.There are a large number of structural traps in the EARS.The oil and gas resources are mainly concentrated in the Cenozoic petroleum system.(4)The main controlling factors of oil and gas enrichment are the distribution and maturity of source rock,sealing condition,structural traps and the horizontal and vertical distribution of sand reservoirs.Thus,the favorable zone of type ??? and ? are classified,and the northern part of Albert basin and lokichar basin are selected as type ? zone. |
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