THE FAVORABLE PETROLEUM ACCUMULATION BELTS AND EXPLORATION TARGETS IN QIONGDONGNAN BASIN ON THE MARGIN OF NORTHERN SOUTH CHINA SEA

The Qiongdongnan Basin is located in the juncture of the Pacific plate, India-Australia plate and Eurasian plate, and characterized by complex Cenozoic tectonic and sedimentary evolution and petroleum geology. The basic tectonic pattern in "E-W zonation and S-N segmentation" made the depressions of the basin different in the distribution of valid source rocks, petroleum accumulation conditions, stratigraphic and sedimentary system and structural framework. Based on the tectonic evolution and sedimentary filling history, combined with oil and gas exploration practice in the basin, we generalized four favorable petroleum accumulation belts, including the Yanan sag and its surrounding area, the northern area of Baodao sag, the No.2 Fracture tectonic belt, and the southern uplift (low uplift) area. According to the petroleum geological features, this paper analyzed in depth the source rocks, reservoir-cap assemblages, petroleum conduction and migration conditions as well as hydrocarbon accumulation models of each favorable petroleum accumulation belt, and main accumulation controlling factors of each belt were also figured out based on above work. Finally, we proposed the prospecting targets of the basin, so as to provide some clues for the future oil and gas exploration and resources assessment.