1. State Key Laboratory of Deep Oil and Gas China University of Petroleum (East China) Qingdao 266580 China
2. Key Laboratory of Unconventional Oil & Gas Development China University of Petroleum (East China) Ministry of Education Qingdao 266580 China
3. School of Energy Resources China University of Geosciences (Beijing) Beijing 100083 China
4. Shale Gas Research Institute PetroChina Southwest Oil & Gas Field Company Chengdu 610051 China
5. Department of Chemical and Materials Engineering University of Alberta Edmonton AB T6G 1H9 Canada