According to the inquiry information, CNOOC Pipeline Engineering Technology Co., Ltd. is a subsidiary of China Offshore Oil Group Co., Ltd., and China Offshore Oil Co., Ltd. is a state-owned large-scale integrated enterprise for oil and gas development, production and sales in China, mainly engaged in the exploration, development and production of offshore oil and gas resources, and also involved in petroleum engineering technical services, petroleum equipment manufacturing, research and development and sales of petrochemical products.