1. National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing), Beijing 102249, P. R. China
2. High Pressure Pipeline Network Branch of Beijing Gas Group Co. Ltd., Dongcheng, Beijing 100010, P. R. China
3. No. 7 Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang, 745000 Gansu, P. R. China