On May 14, 2021, it was learned that the first set of localized shallow water wellhead and Christmas tree independently developed by CNOOC completed the sea trial operation in the Bohai Sea area, which fully verified the functionality and reliability of the underwater production system. It is an important leap forward in the localization of oil and gas equipment and another weapon for China's offshore oil development.

The research and development and technical breakthrough of this system were organized by the General Research Institute. It took three years to complete the research and development, trial production and testing, including 1358 parts. It is a domestic underwater drilling and production equipment with independent intellectual property rights in China. Combined with the operation characteristics of the Bohai Sea area, the joint research team adopted the design principles of integration, simplification and low cost, solved more than 10 industrial problems such as wellhead stability and flow safety assurance, and fully carried out desktop exercises to ensure technical feasibility and operation safety. The sea trial lasted 32 days, carried out 98 operations and 46 diving operations, and successfully completed the installation, function test and recovery of underwater wellhead and Christmas tree.

It is reported that China's Bohai Sea region is rich in oil and gas resources, and most reserves cannot be developed in the conventional mode of establishing offshore platforms due to the contradiction in sea use. Moving the production equipment to the seabed is an important means to solve the contradiction of sea use. Autonomous control of the design, production and application of underwater wellhead and Christmas tree system is the inevitable way for oil and gas production in offshore restricted areas.

Since August 2019, the General Research Institute and Tianjin Branch have jointly tackled key problems, overcome many challenges such as little domestic experience, high technical requirements, short project duration, large epidemic impact and so on, and carried out the research and development of shallow water underwater Christmas tree system, providing a new and reliable development model for shallow water oil and gas fields.

Milijun, general manager of the General Research Institute and project director, said that the successful development of domestic underwater wellhead Christmas tree marks that China has the core technical ability of the overall research and development of underwater wellhead Christmas tree, has broken through the technical bottleneck of the engineering application of key equipment, and has expanded the new operation mode of shallow water oil and gas fields, which will effectively realize the utilization of reserves in more than 10 restricted offshore blocks and provide a solid energy guarantee for social and economic development.

Source: CNOOC Research Institute

Author: Wang Mingchun, Wang Bin, Zhang huizeng