China’s first 2,000-meter-class deepwater subsea Christmas tree, independently developed by China National Offshore Oil Corporation (CNOOC), finished assembly in Tianjin.
Tianjin workers complete the assembly of China’s first 2,000-meter-class deepwater subsea Christmas tree, independently developed by China National Offshore Oil Corporation. [Photo/sasac.gov.cn]
It represents a significant milestone in the building of a self-sufficient offshore oil and gas equipment system and ensuring national energy security.
As a core component in offshore oil extraction, a subsea Christmas tree serves as a crucial junction between the production tubing and subsea pipelines thousands of meters below the seabed. It controls the rate of oil and gas extraction while continuously monitoring and adjusting production parameters. As a fundamental infrastructure for subsea oil and gas production, it ensures the safe isolation of oil reservoirs and supports downhole operations.
A worker checks the assembled deepwater subsea Christmas tree. [Photo/sasac.gov.cn]
The newly assembled Christmas tree features the highest pressure rating, the broadest temperature adaptability and the greatest operational depth in China. The project team tackled key technical challenges through interdisciplinary innovation, achieving breakthroughs in system layout and deepwater operation analysis.
Workers complete the assembly of China’s first 2,000-meter-class deepwater subsea Christmas tree. [Photo/sasac.gov.cn]
Throughout the assembly process, workers maintained rigorous quality control standards, utilizing a 100,000-class cleanroom — comparable to pharmaceutical and food processing standards — to ensure hydraulic flow path cleanliness. The project also developed new welding techniques, optimized quality inspection methods, and enhanced precision in fabricating the base structural framework, achieving a verticality deviation of within 0.5 degrees, fully meeting the high integration requirements of subsea Christmas trees.
The Christmas tree is a significant achievement for CNOOC’s “Qinghai” brand, reinforcing the company’s leadership in subsea equipment development. In recent years, CNOOC has strengthened independent research and technological innovation, establishing a comprehensive subsea equipment R&D, manufacturing and testing platform. This has enabled the independent development and production of more than 10 critical subsea components, including subsea manifolds and subsea distribution unit connectors.
The assembled deepwater subsea Christmas tree [Photo/sasac.gov.cn]
(Executive editor: Wang Ruoting)
