Institution: | 1.Research Institute of Oil Exploration and Development, Changqing Oilfield Branch Company, PetroChina, Xi '' an, Shaanxi 710021, P R of China; 2.College of Chemistry and Molecular Science, Wuhan University, Wuhan, Hubei 430072, P R of China; 3. National Engineering Laboratory of Exploration and Development of Low Permeability oil and gas field, Xi '' an, Shaanxi 710021, P R of China |