[1] Xian Shiyou Univ, Shaanxi Univ Engn Res Ctr Oil & Gas Field Chem, Xian 710065, Peoples R China
[2] Xian Shiyou Univ, Shaanxi Prov Key Lab Environm Pollut Control & Re, Xian 710065, Peoples R China
[3] Xian Petr Great Petr Technol Co Ltd, Xian 710075, Peoples R China
[4] PetroChina Oilfield Co, Xian Changqing Chem Grp Co Ltd, Changqing Oilfield, Xian 710200, Peoples R China
[5] Washington State Univ, Dept Crop Soil Sci, Pullman, WA 99163 USA
[6] North Dakota State Univ, Dept Stat, Fargo, ND 58102 USA