Geochemical characteristics and hydrocarbon generation potential evaluation of source rocks in the deepwater area of Qiongdongnan Basin

The deep-water area of Qiongdongnan Basin has a low degree of exploration.The evaluation of and research on the hydrocarbon generation potential of the marine-terrestrial transitional and marine source rocks in this area is related to the future direction of oil and gas exploration.Through organic carbon content(TOC)determination, rock pyrolysis analysis, microscopic composition identification, vitrinite reflectance(Ro) test and other experimental analysis, this paper systematically analyzes the geochemical characteristics and hydrocarbon generation potential of different types of source rocks in the deep water area of Qiongdongnan Basin.The results show that the source rock organic matter abundance in the deepwater area of Qiongdongnan Basin is the highest in the Yacheng Formation, with an average TOC of 1.37 %; the Lingshui Formation and Sanya Formation rank the second, with an average TOC of 0.91 % and 0.99 %; the Meishan group is relatively low, with an average TOC of 0.78 %.The degree of thermal evolution of organic matter is mainly in the mature stage of Oligocene, and the Miocene is mainly in the low-mature-mature stage.Organic matter types are mainly type Ⅲ in Oligocene, some are type Ⅱ₂, and Miocene are mainly type Ⅱ₂ and type Ⅲ.Comprehensive evaluation shows that the Yacheng Formation is a medium to good source rock with strong hydrocarbon generation potential; the Lingshui Formation and Sanya Formation are medium source rocks with relatively good hydrocarbon generation potential.