IDENTIFICATION OF STRUCTURAL TRANSFER ZONES ON SOUTHEAST SLOPE OF BODONG SAG AND ITS IMPLICATIONS FOR HYDROCARBON ACCUMULATION

Based on newly acquired drilling and 3-D seismic data, the forming mechanism of the flower-like structural zone on the southeast slope of the Bodong Sag is studied and the mechanisms of hydrocarbon accumulation summarized through comprehensive analysis of structure styles and fault features as well as their relationship with hydrocarbon migration and accumulation. Results show that there are several structural transfer zones on the southeast slope of the Bodong Sag. They play a part of role in adjusting the local tectonic deformation and could be used as a clue to divide structural belts. The structural transfer zones may divide the slope belt into three similar flowerlike structure tectonic belts, i.e. the west, central and east, all extending in northeast direction. The structural transfer zones control the formation and distribution of the shallow-water deltaic body of the Lower Member of the Minghuazhen Formation, and are the favorable locations for pinching-out of sand bodies. NEE-strike faults may be blocked by SN transfer faults and form structural traps and structural-lithologic traps which have great exploration potential. The three faults to the south of the three flowerlike structural belts may provide favorable pathways for oil and gas migration and accumulation. Furthermore, in the south, the dense fault zones in en echelon pattern may obstruct the oil and gas migration. Based on the above-mentioned factors, an oil and gas accumulation model is proposed in this paper.