Characteristics of hydrocarbon source rocks in the Permian Maihanhada Formation in Yagan area of Ejina Banner,western Inner Mongolia,China

Based on the study on the lithologic features and hydrocarbon geochemical characteristics of dark mudstone and shale of Permian Maihanhada Formation,the authors summarize longitudinal distribution of source rocks,organic matter abundance,kerogen type and thermal evolution characteristics.The source rocks of Permian Maihanhada Formation are centralized distributed,and the total thickness of dark mudstone and shale is 296.9m.The average organic carbon content is 0.59%,and the values of sample more than 0.3% account for 92.86%.The kerogen type is dominated by Ⅱ-Ⅲ type,and the average vitrinite reflectance is 1.08%,which shows that kerogen has turned into mature stage.Analysis on biomarker of Pr/Ph ranges from 0.64 to 0.78,which shows strong reduction.It is concluded that the source rocks of Permian Maihanhada Formation have good hydrocarbon generation conditions.