Formation conditions and favorable exploration zones of shale gas on the southern margin of Junggar Basin

Based on analyzing the distribution, thickness, area, total organic carbon content, thermal evolution, type of organic matter and petrographic composition of the shale on the southern margin of Junggar Basin, the authors hold that the Jurassic Badaowan, Sangonghe and Xishanyao Formation, the Permian Lucaogou Formation, Hongyanchi Formation and the Carboniferous strata are favorable formations for shale gas exploration. Through an analysis of enrichment conditions of favorable horizons of shale gas and by using the method of superimposing vitrinite reflectance (Ro) isoline, mudstone thickness isoline and total organic carbon content (TOC) contour, the authors determined that the Jurassic strata of the transition region of the northwestern margin of Homato anticline belt, Shawan sag and Monan convex, the Jurassic strata of transition region of Fukang sag and Fukang fracture belt, the Permian strata of Dabancheng sag and Yongfeng sag with shallow buried depth in Chaiwopu depression and the Carboniferous strata of Qigu fault fold zone with shallow buried depth ae favorable places for shale gas exploration.