Influence of Paleogene Structural Pattern on Lithologic Reservoir:A Case Study of Qikou Sag

In this paper,we discuss the influence of structural figuration and structural dynamics on the transporting and reservoiring system in the Qikou sag.The results show that the Paleogene graben faults generated complex half graben-like framework on NW-SE orientation and complex duplex fault graben on N-S orientation in the Qikou sag,constrained by the Cangdong extensional fault system and Qikou extensional fault system.On a plane,the structural palaeogeomorphology pattern with the multi-convex and multi-concave,convex and concave separation formed a favorable space for lithologic reservoirs.The tectonic style of Qikou sag controlled the distribution of hydrocarbon accumulation.The main faults control the oil and gas migration and accumulation and secondary faults rework the oil and gas distribution and form the advantages conduit system.Both favorable reservoir facie and structural slope are prone to the formation of favorable trap.In the Qikou sag,we conclude four types of oil-gas accumulation,i.e.steep slope,gentle slope,broken joint associated with near-source,intrabasinal knick zone.The selected exploration targets have been verified by drilling instance.