1. Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610213, China
2. College of Energy, Chengdu University of Technology, Chengdu 610059, P. R. China
3. Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province, Chengdu, Sichuan 610213, China
4. Engineering Department, PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610066, China