1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
2. Key Laboratory of Oil and Gas Production, CNPC, Beijing 100083, China
3. Engineering and Technology Department, Qinghai Oilfield, PetroChina, Dunhuang 736202, China
4. Drilling and Production Technology Research Institute of Qinghai Oilfield PetroChina, Dunhuang 736202, China