Research on Evaluation and Distribution of Source Rocks in Sikeshu Sag of the Southern Junggar Basin

Sikeshu Sag was a secondary structure unit located in the west of southern Junggar Basin.The potential force and its distributive characters were clarified for the purpose of further analyzing its hydrocarbon accumulation mechanism and predicting its distributive rules.By systematically analyzing the drilling and geochemical data,source rocks in Anjihai Formation of the lower-middle Jurassic and Paleogene were comprehensively evaluated,combined with seismic and sedimentary facies analysis and basin modeling methods,the distribution of the source rocks was objectively predicted.Study results show that the main source rocks are lacustrine dark mudstones in the sag,dark rocks in lower Jurassic Sangonghe Formation are large thickness with high organic matter abundance,good type and a high degree of thermal evolution,they are main source rocks in the area.The distribution of source rocks is obviously controlled by tectonic-sedimentation pattern,the hydrocarbon is mainly located in the central-southeast of the sag,and its quality has been gradually poor from the south to the north.