1. Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West ChinaMinistry of EducationXi'an Shiyou University Xi'an 710065 Shaanxi P. R. China
2. State Key Laboratory of Oil and Gas Reservoir Geology and ExploitationChengdu University of Technology Chengdu 610059 Sichuan P. R. China
3. Key Lab of Coal Resources Exploration and Comprehensive UtilizationMinistry of Natural Resources Xi'an 710065 Shaanxi P. R. China
4. School of Materials Science and EngineeringShaanxi University of Science and Technology Xi'an 710021 Shaanxi P. R. China