INTERNATIONAL PATENT: CHINA NATIONAL PETROLEUM CORPORATION, 中国石油天然气集团有限公司, CNPC ENGINEERING TECHNOLOGY R&D COMPANY LIMITED, 中国石油集团工程技术研究院有限公司 FILES APPLICATION FOR "COMPOUND FOR OIL-BASED DRILLING FLUID VISCOSITY REDUCER AND OIL-BASED DRILLING FLUID VISCOSITY REDUCER"

GENEVA, April 5 -- CHINA NATIONAL PETROLEUM CORPORATION (9 Dongzhimen North StreetDongcheng District, Beijing 100007), 中国石油天然气集团有限公司 (中国北京市东城区东直门北大街9号), CNPC ENGINEERING TECHNOLOGY R&D COMPANY LIMITED (No.1 Building,No.5 Courtyard, Huanghe StreetChangping District, Beijing 102206), 中国石油集团工程技术研究院有限公司 (中国北京市昌平区黄河街5号院1号楼) filed a p...