1. State Key Laboratory of Petroleum Pollution Control, Xi’an Shiyou University, Xi’an 710065, China
2. Shaanxi Province Key Laboratory of Environmental Pollution Control and Reservoir Protection Technology of Oilfields, Xi’an Shiyou University, Xi’an 710065, China
3. Oil & Gas Technology Research Institute Changqing Oilfield Company, Xi’an 710060, China
4. Xi’an ChangQing Petrochemical Corporation Co., Ltd., Xi’an 710018, China
5. Department of Statistics, North Dakota State University, Fargo, ND 58102, USA