Late Hydrocarbon Generation In Baicheng Sag Of The Tarim Basin

Kuqa depression is located in the north of Tarim basin,between the Tarim uplift and the Tianshan orogenic belt.Influenced by multiple periods of tectonic movement,the large thrust fold system and a series of thrust faults formed in front of Tianshan mountains,forming the tectonic pattern of "four belts and three depressions" in the Kuqa depression.Baicheng sag is located in the middle of Kuqa depression,which divides the Crasu tectonic belt and the Qiulitage tectonic belt.In this study,the types and maturity of Jurassic source rocks were analyzed,and the hydrocarbon generation of Jurassic source rocks was studied by basin simulation technology.The comprehensive evaluation of Jurassic source rocks in Baicheng sag shows that the source rocks are thick in the middle and lower part and thin in the upper part.On the plane,the sedimentary center migrated southward from the section of Kapusaliang river to the line of tiger platform to the section of awat river to the line of da-bei well 1,and the distribution changed from north thick to south thin to north-south symmetry.YangXia group and gyzyl nur hydrocarbon source rocks belong to medium level of hydrocarbon source rocks,belong to ? type of organic matter.Chuck mark set of hydrocarbon source rocks belong to medium-good level of hydrocarbon source rocks,organic matter type is ? type.The burial history,thermal evolution history and hydrocarbon generation history were simulated by combining geological data,geochemical data,well logging and seismic data with basin simulation technology.The simulation of burial history shows that the maximum burial depth of Jurassic strata in the eastern part of Baicheng sag is the deepest,followed by the middle part and the western part.The deposition rate decreases from east to west.The sediment thickness is the deepest in the east,the second in the middle,and the shallowest in the west.The simulation study of thermal evolution history shows that the thermal evolution degree of Baicheng sag gradually increases from west to east,and the overall thermal maturity is relatively high,and the hydrocarbon generation threshold is not different.The simulation of hydrocarbon generation history shows that the source rocks in Baicheng sag are in the period ofrapid hydrocarbon generation and in the stage of mass generation.In Kuqa depression,the simulation results of Yangxia depression and Wushi depression show that the thickness of Jurassic strata in Baicheng depression is the largest,followed by Yangxia depression and Wushi depression.Baicheng sag first entered the stage of low maturity,followed by Yangxia sag and Wushi sag.In the degree of thermal evolution,Baicheng sag is the highest,Yangxia sag is the second,Wushi sag is the second.The three depressions are all in the stage of hydrocarbon generation,and the accumulative amount of hydrocarbon generation is the highest in Baicheng depression,followed by Yangxia depression and Wushi depression.