The Da'anzhai member of the Lower Jurassic Ziliujing formation is the most favorable layer for the development of continental shale oil in the Sichuan basin,and has huge potential in shale oil exploration.However,there is a lack of systematic research on the ther-mal evolution history of this formation.Using the simulation system for petroliferous basins,the differences in the thermal evolution and hy-drocarbon generation of the shales in Da'anzhai member between the northern part and the central part of the central Sichuan basin were comparatively analyzed,and their impacts on shale oil enrichment were discussed.The thermal evolution degree of the shale of Da'anzhai member in the study area gradually increases from southwest to northeast,and the shale can be divided into a highly matured zone and a matured zone on the plane.The highly matured zone is located in the northern part of the study area,with vitrinite reflectance ranging from 1.3%to 1.7%,mainly developing Type Ⅲ organic matter.The early oil generation occured in the early Late Jurassic,and the oil generation peaked at the end of Late Jurassic,experiencing two phases of hydrocarbon generation.The matured zone is located in the central to south-ern parts of the study area,with vitrinite reflectance ranging from 0.9%to 1.3%,mainly developing Type Ⅱ1-Ⅱ2 organic matter.The sedi-mentary thickness of the Jurassic is relatively small,the early oil generation occured at the end of the Late Jurassic and reached the peak in the Early Cretaceous,with only one period of hydrocarbon generation.Compared with the northern area,a large set of organic-rich shales deposited in the central area,which provieded a solid material basis for shale oil in the Da'anzhai member.However,the tectonic uplift and stratum erosion since the Paleogene posed a certain destructive effect on the preservation of oil and gas in this area.
Sichuan basinLower JurassicZiliujing formationDa'anzhai memberthermal evolution historyhydrocarbon generation ca-pacitypreservationshale oil and gas
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