苏北盆地走滑断层特征与油气聚集关系

苏北盆地石港、汊涧、吴堡断层体系,平面上主干断层具有线性主位移带、马尾状撇裂和雁列入字型构造的组合特征;剖面上呈现锥形破裂、强制单斜层和破碎主位移带的构造特征;断旁岩石则可见到扭性、压性破裂面等地质现象。这些特征反映石港、汊涧、吴堡断层体系应属离散型右行走滑断层。经应力分析,苏北盆地受伸展作用和右行走滑双重营力的地质作用,而右行扭动是诱导形成走滑断层的主因,主要受郯庐断裂带活动的控制。正是这些断层体系所具有的离散型右行走滑特征控制了苏北盆地的油气圈闭形成、圈闭的平面分布、以及油气的运聚模式。

Relation between features of strike-slip faults and hydrocarbon accumulation in Subei basin

The Shigang, Chajian and Wubao fault systems in Subei basin represent, laterally, combined characteristics of a major fault with main linear shift zone, horsetail splays and en echelon lambda-type structures, and, vertically, structural features of cone-like fracture, forced monocline and fractured main shift zone. Shear and compressive fracture planes can be observed in rocks beside the faults. Based on the above characteristics, it is believed that the Shigang, Chajian and Wubao fault systems are of discrete-type right lateral strike-slip faults. Stress analysis indicates that Subei basin has experienced both agents of extension and right lateral strike-slip, while right lateral wrench movement is the main cause of strike-slip faults, which has been controlled by Tanlu fracture zone. It is the features of discrete-type right lateral strike-slip of the Shigang, Chajian and Wubao fault systems that control the formation and distribution of oil and gas traps, as well as the migration and accumulation of oil and gas in Subei basin.