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. National Engineering Research Center of Oil & Gas Drilling and Completion Technology, (China University of Petroleum (East China)), Qingdao 266580, P. R. China