Permian hydrocarbon source rock evaluation and hydrocarbon generation in middle-upper Yangzi region

Middle-upper Yangzi region has experienced multiphase composite superposition of prototype basin.According to lower limit standard of organic carbon content in the hydrocarbon source rocks,based on the analysis of 49 reconnaissance profiles and rich hydrocarbon source rock samples,the analysis of the Permian hydrocarbon source rocks of middle-upper Yangtze region covering sedimentary environments,distribution range,organic geochemical characteristics and hydrocarbon generation has been carried out.Lower Permian hydrocarbon source rocks are widely distributed,belong to regional high-quality hydrocarbon source rocks,which deposited in the deep water-deep shelf.In north,it is surrounded by Qinling uplift,in west,by Kangdian Gulu-Baoxing uplift,in south,by Qianzhong uplift and in southeast,by Jiangnan xuefeng uplift.Organic types is mainlyⅠ-Ⅱand kerogen type is given priority to type-1.It is an important gas source rock for Permian and Triassic gas reservoir in Sichuan.Hydrocarbon source rocks in Permian system mainly include argillaceous rock of coal seam from Longtan and Dalong formation,and belong to better hydrocarbon source rocks with wide distribution.The parent material type is of type-Ⅱ2-Ⅲkerogen type.The Permian hydrocarbon source rock is generally at high post-mature thermal evolution stage in the study area.