1. School of Energy Science & Engineering, Henan Polytechnic University, Jiaozuo 454000, China
2. Institute of Efficient Development and Utilization of Coal-Measure Gas, Henan Polytechnic University, Jiaozuo 454000, China
3. China United Coalbed Methane Corporation, Ltd, Beijing 100011, China
4. CNOOC Energy Tech-Drilling & Production Co., Tianjin 300457, China