1. Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil & Gas Reservoirs, Xi’an Shiyou University, Xi’an 710065, P. R. China
2. School of Petroleum Engineering, Xi’an Shiyou University, Xi’an 710065, P. R. China
3. National Engineering Laboratory of Low-Permeability Oil & Gas Exploration and Development, PetroChina Changqing Oilfield Company, Xi’an 710021, P. R. China
4. Oil and Gas Technology Research Institute, PetroChina Changqing Oilfield Company, Xi’an 710021, P. R. China
5. No. 6 Oil Production Plant, PetroChina Changqing Oilfield Company, Xi’an 710200, P. R. China