Simulation on Thermal Evolution and Hydrocarbon Generation History of Permian Source Rocks in Southwestern Depression of Tarim Basin

In the southwest Tarim Basin,the Permian source rocks were important hydrocarbon source rocks.According to the data of tectonic characteristics,burial history,stratum thickness,geochemical characteristics of Permian hydrocarbon source rocks,sedimentary facies,lithology analysis etc,in combination with the features of present geothermal field,abnormal thermal events and thermal evolution history,the simulation of thermal evolution and hydrocarbon generation history of Permian source rocks in southwest depression of Tarim Basin were studied with kinetic parameters of the organic phase B(Ⅱ) by fitting simulated values of the EASY % R o model and measured vitrinite reflectance values.Research result shows that during the Triassic,a large-scale of hydrocarbon generation and expulsion are started in Permian source rocks,the hydrocarbon generation center is located near Well Keshen 1and Well Yucan 1of Yecheng Sag,after the Triassic,hydrocarbon generation is suspended,until the Neogene period,there starts a large-scale of hydrocarbon generation and expulsion again with the maximum oil-generating capacity of 300×10 4 t/km 2,and the source range is still limited within the depression.