2. Hebei Huabei Petroleum Engineering Construction Co., Ltd., Renqiu 062552, Hebei, China;
3. Nanning Oil andGas Transportation Branch of State Pipe Network Group Southwest Pipeline Co., Ltd., Nanning 530200, China;
4. AssociatedGas Comprehensive Utilization Project Department of PetroChina Changqing Oilfield Company, Xi’an 710016, China