关键词: 歧口凹陷, 构造样式, 配置关系, 成藏模式

Abstract: Based on analysis of geological structural pattern of Qikou Depression and Combined with structural dynamic mechanism, this article focuses on the influences of the depression on the conducting system and reservoir system as well as its influences on oil and gas accumulations. The results indicate that the NW-SE Paleogene complex fault graben structure and the N-S complex duplex fault graben structure of Qikou Depression were mainly controlled by Cangdong extensional fault system and Qikou extensional fault system, forming Paleo-landform pattern on the plane with a multiple of convexes and concaves and creating favorable space for development of lithological oil and gas reservoirs. The influences exerted by the structural pattern of Qikou Depression on controlling oil and gas accumulations can be found in such ways: When oil and gas were migrating, the main faults controlled oil and gas accumulations while the secondary faults transformed oil and gas distribution, forming the advantageous conducting systems. Favorable reservoir belts, structural slope breaking belts and favorable traps developed at the time of oil and gas accumulations. Based on the previous studies of oil and gas accumulations model, four patterns of accumulations were summarized as follows: steep slope accumulations model, gentle slope accumulations model, stairsbroken near-source accumulations model, and basin-inside slope breaking accumulations model. With exploration targets optimized, good results were achieved in the actual drilling efforts.