1. Southwest Petroleum University, Chengdu 610500, P. R. China
2. China University of Petroleum Beijing, Beijing 102249, P. R. China
3. PetroChina Changqing Oilfield Co, Xi’an, Shaanxi 710021, P. R. China
4. Sinopec Northwest Oilfield Co, Urumqi 100728, P. R. China
5. Research Institute of Petroleum Exploration and Development, Beijing 100083, P. R. China