1. Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gas Field Company, Chengdu610213, Sichuan, P. R. China
2. Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province, Chengdu610213, Sichuan, P. R. China
3. Development Department, PetroChina Southwest Oil & Gas Field Company, Chengdu610066, Sichuan, P. R. China
4. College of Energy, Chengdu University of Technology, Chengdu610059, P. R. China