1. Petroleum Engineering School, Southwest Petroleum University, Chengdu 610500, China
2. China United Coalbed Methane Company, Taiyuan, Shanxi 030000, China
3. Southwest Oil and Gas Field Branch Natural Gas Research Institute, Chengdu 610213, China
4. Sinopec Petroleum Engineering Zhongyuan Co., Ltd., Zhengzhou 450000, China
5. School of Engineering, Cardiff University, Cardiff CF24 3AA, U.K.