辽东湾坳陷JX1-1构造发育演化及油气勘探意义

Development and evolution of the Structure JX1-1 in Liaodong Bay Depression and its significance in petroleum exploration

JX1-1构造发育于辽东湾坳陷郯庐断裂西支,具有复杂的构造样式和发育演化过程,对油气的聚集产生重要影响。本文充分利用三维地震资料详细表征其构造样式和各断层的展布特征,探讨其发育演化过程及油气勘探意义。研究表明,JX1-1构造发育于沉积盖层中,向下并未贯穿到深部基底。该构造的发育特征与对称型松弛弯曲处走滑双重构造具有很大的相似性,但也存在一些明显的差异。JX1-1构造的发育起始于一系列雁行排列的T破裂、少量右阶排列的P破裂以及南北两端Y破裂的形成;在走滑变形过程中,各破裂的末端发生侧向扩展,中部的T破裂与两条P破裂连接形成张性走滑弯曲;随后,走滑弯曲部位两侧的T破裂陆续通过与P破裂连接或自身的末端扩展产生一系列叠置的断片,从而形成了现今JX1-1的构造样式。JX1-1大油田的形成除与该区具有充足的油气供应外,还得益于该构造部位的很大一部分走滑位移转变为垂向位移,形成了有效的断层圈闭,为油气的大量富集提供了有利的储集空间。

The Structure JX1-1 developed on the west branch of Tan-Lu fault belt in Liaodong Bay Depression.It has a complex structural pattern and evolution history,which is very important for petroleum accumulation.In this paper 3D seismic data is used to characterize its pattern and fault distribution characteristics,to discuss its tectonic evolution,and to reveal its significance in petroleum exploration.The study indicates that the StructureJX1-1 developed only in the sedimentary cover and did not extend downward into the basement.The characteristics of the Structure JX1-1 are very similar to those of a symmetrically releasing bend strike-slip duplex structure,but some obvious differences also exist between them.The development of the Structure JX1-1 began with the formation of some en-echelon-arranged fractures T,a few right-stepping fractures P,and the fractures Y to the north and south ends.During the strike-slip deformation,two tips of each fracture propagate laterally,and the central fractures T links with its nearby fractures P to define a releasing bend.Then,the fractures T on the opposite sides of the bend sequentially link with fractures P or propagate laterally toward the earlier-developed faults to produce a serious of horses that are arranged in a piggy-back fashion,forming the present structural pattern.A large oil field formation of the Structure JX1-1 is not only related to sufficient petroleum source supply,but also associated with the transformation from strike-slip displacement to vertical displacement.As a result,effective fault traps developed,which provided favorable space for petroleum accumulation.