车西洼陷构造演化对油气成藏的控制作用

Tectonic Controls on the Hydrocarbon Accumulations in the Chexi Sag

车西洼陷新生代构造演化经历了伸展半地堑充填、断块强烈活动、断块活动复杂化、埋深加大四个阶段。构造演化对油气成藏具有明显的控制作用。一方面,构造活动为沉积物质提供了有利的沉积环境和生烃条件,形成了大量的铲式构造样式,改善了扇体的储集物性,断层活动强弱的周期性变化也形成了多套生储盖体系。另一方面,断层活动形成了大量断块、逆牵引等有利圈闭条件,断裂活动强弱变化,使得断裂开启和闭合,为油气运移与保存创造了有利条件。

The Cenozoic tectonic evolution in the Chexi sag can be divided into four stages,namely the extensional half-graben filling stage,the strong activity stage of fault blocks,the complication stage of fault blocks movements and the increasing buried depth stage.The tectonic evolution obviously controlled the oil and gas accumulation.Firstly,tectonic activity created favorable depositional environment and hydrocarbon generation conditions.Secondly,it resulted in many listric structures and improved the reservoir potential of the fan bodies.Thirdly,the rhythmic fault activities led to the formation of several sets of source-reservoir-cap systems.Lastly,fault activities formed lots of fault blocks,rollover structures,which were favorable oil traps,meanwhile,the changing fault activities resulted in the close-or open-system behaviors of the faults,and correspondingly the channels for oil migration or loci for oil preservation,respectively.