1. State Key Laboratory of Coal Resources and Safe Mining, College of Geosciences and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China
2. CNOOC EnerTech-Drilling & Production Co., Tianjin 300457, China
3. Department of Energy and Mineral Engineering, Geosciences, EMS Energy Institute and the G3 Center, Pennsylvania State University, University Park, Pennsylvania 16802, United States