Multi-Layer Superposed Coalbed Methane System in Southern Qinshui Basin, Shanxi Province, China

作     者：Zheng Zhang Yong Qin Xuehai Fu Zhaobiao Yang Chen Guo 

作者机构：School of Resources and Goesciences China University of Mining and Technology Key Laboratory of Coalbed Methane Resource and Reservoir Formation Process Ministry of EducationChina University of Mining and Technology 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2015年第26卷第3期

页      面：391-398页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 0704[理学-天文学] 

基　　金：financially supported by the National Natural Science Fund of China (No. U1361207) the Coalbed Methane United Fund of Shanxi Province (No. 2012012001) the National Science and Technology Key Special Project of China (No. 2011ZX05034-04) 

主　　题：multi-coalbed coalbed methane system fluid pressure system equivalent reservoir pressure gradient formation mechanism 

摘      要：Multi-coalbed developed in Carboniferous–Permian coal-bearing strata of southern Qinshui Basin, and different coal-bearing segments have different coalbed methane（CBM） reservoiring characteristics. Analysis of previous studies suggests that the essence of an unattached CBM system is to possess a unified fluid pressure system, which includes four key elements, namely, gas-bearing coal-rock mass, formation fluid, independent hydrodynamic system and capping layer condition. Based on the exploration and exploitation data of CBM, it is discovered that the gas content of coal seams in southern Qinshui Basin presents a change rule of non-monotonic function with the seam dipping, and a turning point of the change appears nearby coal seam No. 9, and coal seams of the upper and the lower belong to different CBM systems respectively; well test reservoir pressure shows that the gradient of coal seam No. 15 of the Taiyuan Formation is significantly higher than that of coal seam No. 3 of the Shanxi Formation; the equivalent reservoir pressure gradient of coal seam No. 15 ＂jumps＂ obviously compared with the reservoir pressure gradient of coal seam No. 3 in the same vertical well, that is, the relation between reservoir pressure and burial depth takes on a characteristic of nonlinearity; meanwhile, the vertical hydraulic connection among the aquifers of Shanxi Formation and Taiyuan Formation is weak, constituting several relatively independent fluid pressure systems. The characteristics discussed above reveal that the main coal seams of southern Qinshui Basin respectively belong to relatively independent CBM systems, the formation of which are jointly controlled by sedimentary, hydrogeological and structural conditions.