1. School of Energy Resources, China University of Geosciences, Beijing 100083, China
2. School of Gemology and Material Technology, Hebei GEO University, Shijiazhuang 050031, China
3. PetroChina Southwest Oil & Gasfield Company, Chengdu 610041, China
4. Shale Gas Research Institute, PetroChina Southwest Oil & Gasfield Company, Chengdu 610041, China