非洲中部Muglad盆地Fula凹陷断裂演化及对油气的控制作用

The fault evolution of Fula Sag,Muglad Basin in Central Africa and its hydrocarbon control

Muglad盆地是中非剪切带南侧的一个中⁃新生代陆内裂谷盆地,Fula凹陷是其北部的一个富油气凹陷。对于该地区断裂控烃作用研究,前人主要集中在断裂控制圈闭形成、阻止油气继续运移及为油气运移聚集提供通道等3方面,而对其他控制作用研究不足。故本文基于地震、地质及地化资料,对Fula凹陷断裂形成演化及对油气的控制作用等方面进行了研究。结果表明:1)Fula凹陷断裂第一、二期裂陷期活动性较强,控制“继承型”凹陷的形成;2)第一、二裂陷期断裂活动性较强,使Fula凹陷主要发育Abu Gabra组烃源岩与中部成藏组合;3)中央断裂带与西部陡坡带内断裂控制构造及构造—岩性油气藏的形成与分布,Abu Gabra组烃源岩生成的油气通过中央断裂带的主干断裂及断层①向上部圈闭中运移成藏。

The Muglad Basin is a Mesozoic⁃Cenozoic rift basin in Central Africa,and Fula Sag is a hydrocarbon⁃rich depression in the north of Muglad Basin.For fault control on hydrocarbon in this area,previous studies found the faulting effect not only controlled trap forming,but also provided barrier and path for hydrocarbon migration.However,there is a lack of the research on other controls.So,we analyzed fault developmental stages and their hydrocarbon controls in this area based on seismic,geological and geochemical data.The results show:1)Faults in Fula Sag are more active during the first⁃and⁃second⁃rift stage,which controls the formation of“inherited”sag;2)The faults are more active in the first⁃and⁃second⁃rift stage,which makes this sag mainly develop AG Formation source rock and middle reservoir⁃forming combination;3)Faults in central fault zone and western slope belt control structural and structural⁃lithologic reservoir forming and distribution,and the hydrocarbon generated by source rock in Abu Gabra Formation migrates and accumulates through main faults in central fault zone and①fault.