Control of thermal evolution of source rocks on hydrocarbon distribution in Kuqa foreland basin, Tarim Basin, NW China

Abstract

Kuqa foreland basin is the foreland basin with the highest degree of oil and gas exploration and research in China. On the basis of deep understanding of hydrocarbon accumulation conditions and accumulation process in Kuqa foreland basin, the oil and gas distribution law of Kuqa foreland basin is summarized: (1) In the KS2-KS5 well block in the center of the basin, the maturity of source rock Ro is more than 2%, and the maximum is more than 3.5%, High over mature dry gas reservoirs are mainly formed in these area. (2) In Bozi-Dabei area at the west end of the basin and Dina-Yinan areas in the east end, the maturity Ro of source rocks mainly ranges from 1.2% to 2.0%, mainly forming condensate gas reservoirs with low condensate oil content. (3) In the northern structural belt and southern slope belt of the periphery of the basin, far away from the mature center of the source rock, the maturity of the source rock is relatively low and Ro is between 0.6% and 1.2%, which mainly forms oil and gas reservoirs and condensate reservoirs with high condensate oil content. From east to west, there are differences in structural characteristics, reservoir types, reservoir forming characteristics and resource potential of different structural sections, which are characterized by oil and gas enrichment in the middle section. The distribution and phase difference of oil and gas in Kuqa foreland basin are mainly controlled by the maturity of source rocks and the process of hydrocarbon accumulation. Through the understanding of hydrocarbon accumulation law and oil-gas distribution characteristics, it is of certain guiding significance to determine the next step exploration direction of Kuqa foreland basin.