China's first domestically developed subsea Christmas tree for oil drilling. Photo: courtesy of China State Shipbuilding Corporation

China's first domestically developed subsea Christmas tree for oil drilling was recently installed and officially put into operation in the South China Sea, breaking the long-term monopoly of foreign products in this field, the Global Times learned from its developer on Monday. 

According to a statement the China State Shipbuilding Corporation sent to the Global Times, the corporation's subsidiary company, Chongqing Qianwei Technologies Group, has successfully installed the subsea Christmas tree in the Yingge Sea, South China's Hainan Province, marking an important step in the country's deep-water oil and gas exploration. 

The subsea Christmas tree is a core piece of equipment used in subsea production systems in the petroleum industry. It is used to connect oil and gas from deep in the formation to external oil and gas transport pipelines. As an intelligent "faucet" at the wellhead, it controls the exploitation rate of oil and gas and monitors and adjusts the production situation in real time. It is a key piece of equipment for the development of deep-water oil and gas fields.

"The design of the equipment is usually required for water depths of up to 1,500 meters, rated to 10,000 psi, which is equivalent to 150 times atmospheric pressure. The lowest rated temperature is minus 18 degrees, and it requires a 20-year service life, which places extremely stringent requirements on the equipment's sealing strength and material bearing capacity," Liu Haijun, project manager of the subsea Christmas tree, told the Global Times. 

Previously, subsea Christmas tree technology had been monopolized by companies from European and American countries, which held about 90 percent of the market and thus led to a long acquisition cycle, high price and difficult maintenance. This has long restricted China's offshore oil industry from working independently in deep water, according to Liu. 

The application of the home-made subsea Christmas tree indicates that China has successfully mastered the design, manufacturing and testing technology of this key piece of equipment. For the next step, the equipment will be used to develop gas reservoirs around the Ledong platform of the Dongfang 1-1 gas field in the South China Sea, the Global Times learned from the company. 

By using the subsea Christmas tree system, gas wells can produce about 200 million cubic meters of natural gas per year, the company said.