Multi-source genesis of continental carbonate-rich fine-grained sedimentary rocks and hydrocarbon sweet spots

JIANG Zaixing,KONG Xiangxin,YANG Yepeng,ZHANG Jianguo,ZHANG Yuanfu,WANG Li,YUAN Xiaodong

Table 1 Mineral compositions of shales in continental basins in China.

Basin Sag Formation Mineral composition/% Calcite Dolomite Clay Quartz Feldspar Pyrite Analcite Evaporitic mineral Bohai Bay Basin Dongying Sag[4, 13] Upper part of 4th member and lower part of 3rd member of Eocene Shahejie Formation (Es3L & Es4U) 37.5 10.3 20.3 23.1 6.3 2.5 Zhanhua Sag[4, 13] Lower part of 3rd member of Eocene Shahejie Formation (Es3L) 30.8 8.3 25.4 24.0 6.0 4.1 1.3 Shulu Sag[4, 13] Lower part of 3rd member of Eocene Shahejie Formation (Es3L) 54.3 18.3 14.3 10.3 1.5 1.3 Cangdong Sag[13] 2nd member of Eocene Kongdian Formation (Ek2) 8.0 25.9 14.2 20.5 23.7 0.6 6.8 Nanxiang Basin Biyang Sag[4, 13] 3rd member of Oligocene Hetaoyuan Formation 17.4 10.4 28.9 19.5 18.8 2.8 Jianghan Basin Qianjiang Sag[4] 3rd member of Eocene Qianjiang Formation (Eq3) 9.8 30.9 12.4 6.7 7.6 5.3 27.2 Junggar Basin Jimusaer Sag[13] Middle Permian Lucaogou Formation (P2l) 10.6 26.7 10.4 20.2 30.9 0.9 0.6 Luanping Basin[13] Lower Cretaceous Xiguayuan Formation (C1x) 10.0 18.3 21.7 19.2 28.9 1.2 0.4 0.1 Songliao Basin Gulong Sag[13] Upper Cretaceous Qingshankou Formation 2.4 9.1 34.8 36.2 16.7 Ordos Basin[13] 7th member of Upper Triassic Yanchang Formation (T3y7) 0.7 57.0 22.5 15.0