1. Key Laboratory of Coalbed Methane Resource & Reservoir Formation Process, Ministry of Education, China University of Mining and Technology, Xuzhou 221008, China
2. School of Resources and Earth Science, China University of Mining and Technology, Xuzhou 221116, China
3. School of Science, University of Regina, Regina, Saskatchewan, Canada S4S 0A2
4. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China