渤海湾盆地歧口凹陷扭动构造及其油气地质意义

Characterization and Petroleum Geological Significance of the Wrench Structure in the Transtensional Region:A Case from Qikou Sag

受东部边界郯庐断裂和西部边界太行山前大型走滑断裂的影响,渤海湾盆地中部歧口凹陷区处于伸展与走滑共同作用的地区,利用最新连片采集的超大面积地震资料开展构造研究,发现该区古近纪在发育伸展构造的同时也发育走滑扭动构造,该类构造与古近系内伸展构造共存.在剖面上依据基底和盖层中断裂组合的不同可以分为4类构造样式:走滑-复杂断裂褶皱型、走滑-简单花状构造型、逆冲-简单花状构造型和走滑-挠曲褶皱型.同时,扭动构造带不仅对盆地基底物性的改造有着有利影响,还控制了古物源的入口方式和有利砂体的展布.在前第三系、古近系和新近系构造层中形成了不同类型的有利油气藏,其中古近系挠曲背斜、大型断鼻和地层岩性油气藏以及新近系逆牵引背斜和断鼻翼部都是重要的勘探领域.近两年沿走滑扭动带及其两侧进行的油气勘探已获得成功,对该带研究具深远理论意义及现实意义.

The Qikou sag at the central of the Bohai bay basin lies in the superimposition of the extension and strikeslip, and is controlled by the eastern boundary Tanlu fault and the western boundary Taihang Mountain front strike-slip fault. Through the detailed structural research of the latest large area 3D high precision seismic data, the wrench structures were found as well as the extensional structures in the Paleogene cover of the Qikou sag. On the seismic profiles, the wrench structure can be divided into four types based on the different combination styles of the faults in the basement and the Tertiary cover. They are the slipcomplex faulted fold type, slip-simple flower structure type, thrust-simple flower structure type and the slip-deflecting fold type. Meanwhile, the wrench structure not only improved the physical property of the basement rock but also controlled the entrance of the ancient resource and the distribution of the sand. Different reservoirs formed in the pre-Tertiary, Paleogene and Neogene tectospheres. The Paleogene deflecting folds, huge faulted noses and litho-stratigraphic reservoirs are important exploration fields and the same case with the Neogene reverse drag anticline and the flank of the faulted-noses. The research of the wrench belts is significant for the theory and practice because of the important petroleum exploration success beside the wrench structure belts in last two years.