1. Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education, China University of Mining and Technology, Xuzhou 221008, Jiangsu, China
2. School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
3. Shanxi Coal Geology Geophysical Surveying Exploration Institute, Jinzhong 030600, Shanxi, China