Nanpu Sag is a Meso-Cenozoic petroliferous sag.The sag underwent fault-subsided and depressed stages and possesses episodic sedimentary property.The structural belts within the sag are distributed annularly and could be divided into peripheral uplift-buried-hill structural belt

marginal strutural belt and the central structural belt of the sag.These structural belts are separated into south zone and north zone bounded by Gaoliu Fault.The formation and distribution of traps in the sag were controlled by structural evolution. Traps of anticline and buried-hill types were formed in fault-subsided stage;traps of fault block and fault-antieline types were formed in depressional stage.