环渤中地区新构造运动期断裂活动与油气成藏关系

Relationship between faulting and hydrocarbon pooling during the Neotectonic movement around the central Bohai Bay

周心怀 牛成民 滕长宇

Zhou Xinhuai Niu Chengming Teng Changyu

环渤中地区是渤海海域重要的含油气区,断裂发育,新构造运动期断裂活动对油气的输导与保存具有重要意义.运用断裂活动速率法,通过分析主干断裂沿其走向活动性的变化以及区带内不同活动速率断裂的搭配,综合研究了环渤中地区断裂的活动性与油气聚集保存之间的关系,并从溢出点的位置、断裂输导与保存活动速率的界定、断距与区域性盖层厚度关系对其控藏机制进行了讨论.研究表明,环渤中地区新近系油气藏主要分布在中等或微弱活动断裂附近(活动速率小于25m/Ma);而强烈活动断裂(活动速率大于25m/Ma)主要起垂向输导作用,难以形成浅层的油气聚集,只有在其活动相对微弱的部位才可以使油气聚集成藏.

The area around central Bohai Bay is an important prolific zone,where faults are well developed and faulting during the neotectonic movement played a significant role in migration and preservation of hydrocarbons.The fault activity rate () method was used to study the relationship between faulting activity and hydrocarbon accumulation/preservation in the area based on analysis of activity changes along the strike of main fault and combinations of faults with different within the zone.In addition,the controlling mechanisms of hydrocarbon accumulation were also discussed in respects of the locations of spill points,the definition of fault carrier systems and ,and the relationship between fault throw and thickness of regional caprock.The results indicate that hydrocarbon accumulations in the area are mainly located near faults with moderate or weak activities(<25 m/Ma),while they seldom occur near faults with strong activities(>25 m/Ma) because these faults served mainly as vertical migration pathways,making it hard to form shallow oil accumulations.For these faults,only in areas with relatively weak fault activities can hydrocarbon accumulation occur.

10.11743/ogg20090413