1. College of Chemistry and Chemical Engineering, Southwest Petroleum University, 8 Xindu Avenue, Xindu District, Chengdu, Sichuan 610500, P. R. China
2. Quality, Health, Safety and Environmental Protection Department of Zhejiang Oilfield Company, Hangzhou, Zhejiang, China
3. Natural Gas Exploration and Development Division of Zhejiang Oilfield Company, Luzhou, Sichuan, China
4. Southwest Gas Production Plant of Zhejiang Oilfield Company, Yibin, Sichuan, China