On May 11, China's first set of domestic deepwater underwater oil production trees completed the seabed installation in the Yingge Sea area of Hainan, which is an important part of the underwater oil and gas production system engineering demonstration project led by CNOOC, marking a key step in the development of key technologies and equipment for deepwater oil and gas development in China. The 500-meter-class underwater oil and gas production system engineering demonstration application project implemented by CNOOC marks that China has the ability to design, build and apply complete sets of equipment.

Underwater production system is the key equipment for the development of deepwater oil and gas fields, including underwater wellhead, underwater oil production tree, underwater control system, underwater manifold and other equipment. For a long time, only 5 European and American companies in the world have mastered the integrated manufacturing technology of underwater production systems, resulting in long procurement cycles, high prices and difficult maintenance of this equipment. In 2018, CNOOC took the initiative and boldly proposed the need to use independent research and development of 500-meter-class underwater equipment to develop deepwater oil and gas, and accelerate the breakthrough of key core technologies in deepwater.

The water pressure at a depth of 500 meters is equivalent to about 50 times the atmospheric pressure, in the face of complex environments such as low temperature and complex landforms on the seabed, 20 years of maintenance-free harsh conditions, the sealing strength of underwater equipment, the pressure bearing capacity of materials, the quality of the process and other technical challenges, there is no opportunity for trial and error, any negligence may cause irreparable huge losses.

Even so, Mi Lijun, president of CNOOC Research Institute, who is responsible for the development and design of the 500-meter-class underwater oil and gas production system engineering demonstration application project, believes that the underwater production system is an important part of China's deep-sea process, and it has accumulated more than ten years of underwater design experience, and it is the unshirkable responsibility of CNOOC people to develop deepwater oil and gas in the South China Sea with independent technology.

To achieve autonomy in underwater equipment, it is necessary to realize the autonomy of underwater design technology. However, it is not easy to independently carry out the design of underwater production systems, first, the domestic underwater technology team is in its infancy, and there are only a few talents with experience in deepwater engineering; Second, the maturity of domestic underwater equipment technology is generally low, and a complete underwater production system equipment industry chain has not yet been formed; Third, there is a lack of systematic technical system. In order to control the reliability of the self-designed underwater production system from the source, CNOOC Research Institute comprehensively explored and fully identified the risks of the underwater production system scheme at the source of the design. However, the internationally accepted analysis scheme is based on the underwater production system of mature components, and the underwater equipment developed in this project generally uses domestic components. How to control the application risk of the first set of products relies on the original conventional technical means is very limited.

In order to ensure the smooth implementation and operation of this demonstration project, the research team has developed a set of technical maturity evaluation system based on independent research and development of underwater production systems on the basis of fully digesting and absorbing international underwater product standards and technical management, and conducting a "Ding Ding Xie Niu" analysis of hundreds of key components of each equipment, and can only be applied after the final assessment is qualified to ensure the high reliability of the product and control the implementation risk of the first set of products from the source.

To smoothly apply self-developed underwater equipment, in addition to in accordance with the most stringent international product standards