1. Key Lab of Ministry of Education for Enhancing the Oil & Gas Recovery Ratio, Northeast Petroleum University, Daqing 163318, P. R. China
2. CNPC Research Institute of Safety and Environment Technology, Beijing 102206, P. R. China
3. Key Laboratory of Low-grade Energy Utilization Technologies & Systems, Ministry of Education, College of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China