Abstract:

To evaluate the exploration and development potential of coalbed methane (CBM) and instruct the safety production of coal mine, the reservoir properties in Liuhuanggou coal mine in southern margin area of Jungger Basin were analyzed, including the maceral, fracture and gas content of main coal seams of No.4-5, No.7 and No.9-15. Combined with the data from field drilling data and gas desorption and emission, the geological controlling factors of CBM in this region were investigated from aspects such as structures, sedimentary environments, burial depth of coal and hydrodynamic conditions. The results show that the coal reservoir in this region has favorable properties, in which the pore-fracture system has well developed and the density of micro-fractures reaches to 3,935 per 9 cm²; moreover, the gas content is high, and CBM content in No.4-5 coal seam is from 4.88 to 10.81 m³/t with an average of 6.56 m³/t. The analysis of factors affecting gas content in coal seam indicates that the gas controlling mode gives priority to structure and hydrodynamic conditions. At last, by using the multi-level fuzzy comprehensive evaluation model the CBM favorable region in No.4-5 coal seam is predicted to be the area surrounding boreholes of 29-3 and 28-3.

Key words: southern Jungger Basin, Liuhuanggou, coalbed methane, gas controlling factor, favorable area