Formation conditions and exploration direction of large and medium gas reservoirs in the Junggar Basin, NW China

HU Suyun,WANG Xiaojun,CAO Zhenglin,LI Jianzhong,GONG Deyu,XU Yang

Table 2 The Carboniferous main hydrocarbon-generating sags and hydrocarbon-generating indexes of the source rocks in the three active continental margin belts of the Junggar Basin.

Continental margin belt Sag Area/ km2 Formation Lithology of source rock Thickness of source rock/m TOC/% S1+S2/ (mg·g-1) Types of kerogen Neutron porosity/ % Gas reservoir/Gas-producing site NE Wucaiwan 785 Dishuiquan Formation and Songkaersu Formation of the Lower Carboniferous Dark-grey mudstone, tuffaceous mudstone 100-300 0.5-37.6/ 3.0 0.12-58.00/ 5.20 Ⅱ2—Ⅲ 0.55-3.50/ 1.30 Wucaiwna Dishuiquan 1 530 Dark-grey mudstone, carbon mudstone 100-300 0.5-43.7/ 4.7 0.10-71.40/ 7.30 Ⅱ2—Ⅲ 0.69-2.00/ 1.20 Kelameili Dongdao- haizi 4 700 100-200 No data available, refer to Wucaiwan-Dishuiquan sag Dajing 1 620 Dark-grey mudstone, carbon mudstone 50-100 0.5-4.4/ 2.5 0.02-6.11/ 1.80 Ⅱ2—Ⅲ 0.81-1.70/ 1.00 SE Fukang 1 420 Dishuiquan Formation and Songkaersu Formation of the Lower Carboniferous Dark-grey mudstone, carbon mudstone 75-200 0.5-41.2/ 11.8 0.20-121.40/ 22.60 Ⅱ2—Ⅲ 0.50-1.52/ 0.85 Xiquan2, Xiquan10, Fu26 Jimusaer 2 040 Dark-grey mudstone, tuffaceous mudstone 100-225 2.0-41.2/ 23.4 0.90-79.20/ 39.00 Ⅱ2—Ⅲ 0.64-1.00/ 0.74 WE Mahu—Pen1West 1 580 Chepaizi Formation of the Upper Carboniferous and Jiamuhe Formation of the Lower Permian Dark-grey mudstone, tuffaceous mudstone 50-200 0.5-5.8/ 2.2 0.13-6.60/ 1.61 Ⅱ2—Ⅲ 1.02-3.64/ 1.67 Shawan 1 000 Grey carbon mudstone, tuffaceous mudstone 50-200 0.5-5.8/ 2.2 0.19-20.00/ 2.60 Ⅱ2—Ⅲ 0.70-0.77/ 0.74 Zhongjia2H, Chefeng6, Jinlong43