[1] College of Petroleum Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China
[2] Petroleum Technology Research Institute, Changqing Oilfeild Company, Xi'an, Shaanxi 710021, China
[3] The National Engineering Laboratory of Low Permeability Exploratory Development, Changqing Oilfeild Company, Xi'an, Shaanxi 710021, China