东非大陆边缘构造演化与油气成藏模式探析

近年来,东非海上不断有大型天然气田发现,已成为国际能源勘探的新兴热点。东非地区蕴藏着巨大的油气资源潜力,但其勘探和研究程度很低。在调研大量区域地质和油气地质资料的基础上,通过对东非大陆边缘构造演化特征的分析,从油气成藏要素(烃源岩、储盖组合以及圈闭类型)入手,探讨了油气成藏模式,并对其勘探前景和方向进行了分析。研究结果表明,东非大陆边缘经历了4期构造演化,形成了裂谷叠加被动大陆边缘的双层系盆地结构;主力烃源岩形成于卡鲁裂谷期,主力储层形成于被动陆缘期,在大型三角洲发育区,油气保存条件最好,以构造和构造-地层圈闭为主;油气成藏模式受到构造演化的阶段性、构造变形的横向分带性以及成藏要素的配置关系所控制。 

Tectonic Evolution and Hydrocarbon Pooling Patterns Analysis in East Africa Continental Margin

In recent years,East Africa continental margin where many large gas fields are discovered has become an emerging focus in the international energy exploration.East Africa contains huge potential of oil and gas resources,but the exploration and research degree is low.On the basis of regional geological and petroleum geology data,and the analysis of the evolution process and the hydrocarbon accumulation elements(source rocks,assemblage of reservoir and seal,trap types)of the East Africa continental margin,the hydrocarbon pooling patterns and the prospect of hydrocarbon exploration has been discussed.Research suggests that the East Africa continental margin has experienced four tectonic evolution stages.The passive continental margin sequences overlay the rift sequences,forming the double layer structure of the basins.The major hydrocarbon source rocks formed in the Karoo rift period,while the key reservoir formed in the passive continental margin stage.In areas of large delta development,hydrocarbon preservation conditions are the best,dominated by strctural and structural-stratigraphic trapping.Hydrocarbon accumulation patterns are controlled by the phases of tectonic evolution and horizontal segment of tectonic deformation as well as the configuration of hydrocarbon accumulation elements.