1. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
2. Key Laboratory of Unconventional Oil & Gas Development (China University of Petroleum (East China)), Ministry of Education, Qingdao 266580, P. R. China
3. School of Material Science & Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
4. School of Science, China University of Petroleum (East China), Qingdao 266580, P. R. China