Coal--Type Gas Provinces in China and Their Geochemical Characteristics

Zhang Xiaobao, Xu Yonghang, and Shen Ping

The distribution of coal-type gases in China can be divided into the east gas province, the central gas province and the west gas province.(1) The East gas province lies in the East China Meso-Cenozoic Rift Belt, including Donghai basin and Bohaiwan basin. The ages of gas source rocks are Carbo-Permian and Tertiary. The types of gas reservoirs are a anticline or a hidden mountain-fault block combination reservoir. The CH₄ content of the gases there is 83-90%, with ^dgr¹³C₁ -35.5 to ~-39.9^pmil and ^dgr¹³C₂ -24.0 to ~-26.8^pmil. The ^dgr¹³C of condensate oils associated with the gases ranges from -25.4^pmil to -26.8^pmil. (2) The central gas province is inside the Central China Paleozoic Plates, including Or os basin and Sichuan basin. The gas source rocks are Carbo - Permian and Triassic. The types of gas reservoirs are a anticline-fault combination or a lithological - tectonic combination reservoir. The ^dgr¹³C₁ of the gases there is -37.9 to ~-37.1^pmil, with the ^dgr¹³C of condensate oil accompanying them -25.1 to ~-26.6^pmil. (3) The West gas province is within the West China Late Paleozoic Intracontinental Compressive Belt, including Tarim basin, Jungar basin and Tuha basin. The Age of gas source rocks is Jurassic. The types of gas reservoirs are a anticline or a anticline-fault reservoir. The CH₄ content of the gases there varies from 60 to 90%, with ^dgr¹³C₁ from -38.7 to -43.7^pmil and ^dgr ¹³C₂ rom -25.9^pmil to -29.9^pmil. The ^dgr ¹³C of light oils and condensate oils accompanying the gases changes from 24.3^pmil to 27.8^pmil.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California