1. Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education, Xuzhou 221008, Jiangsu, China
2. School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, Jiangsu, China
3. Institute of Resources & Environment, Henan Polytechnic University, Jiaozuo 454000, Henan, China