Abstract: Coal seam reservoir conditions and development technologies are the major factors that influence China's CBM recovery. CBM recovery can be increased by improving drilling and completion technologies and stimulation technologies. Some shortcomings of commonly-used drilling and completion technologies, fracturing technologies, and gas injection technologies are analyzed, it is believed that the short radius radial horizontal well technology has the function of completion and stimulation and it can increase the single-well productivity substantially. The high-energy gas fracture technology can improve the reservoir conductivity and protect coal reservoir, decrease contamination to coal reservoir caused by water sensitivity, and reduce costs. The gas concentration and flow rate before and after gas injection change with time, indicating that gas mixture enhanced CBM recovery (G-ECBM) has obvious effect.

Key words: CBM, recovery, radial horizontal well, high-energy gas fracture, gas mixture displacement