'Underwater oil trees' grow in the sea

Workers test China's first marine subsea production system at the WEFIC Ocean Equipment workshop in Dongying High-Tech Zone, Dongying city, east China's Shandong Province. (Photo/Liu Zhifeng)

"In the past two years, 11 'oil trees' have gone underwater to extract oil!" exclaimed Sui Zhongfei, chairman of WEFIC Ocean Equipment Manufacturing Co., Ltd, based in Dongying city, east China's Shandong Province, with pride as he stood beside a shallow-water subsea Christmas tree nearly twice his height.

WEFIC's subsea Christmas trees have been applied in various domestic seas and are now reaching global markets.

Sui explained the trees act like "faucets" for oil and gas fields, connecting underground reserves to transportation pipelines, and they control the extraction rate and monitor production conditions in real-time.

The underwater tree consists of 1,358 components, involving material engineering, underwater corrosion prevention, and other specialized fields. The design, manufacturing, and assembly are challenging, and only a few companies worldwide possess the ability to design and manufacture them.

WEFIC invested significantly in technological breakthroughs for underwater Christmas trees in 2019. However, they faced shortages in research funding, talent, and technical expertise.

"We must help the company tackle this 'hard nut,'" said Hu Xianwen, deputy director of the Dongying High-tech Zone Management Committee. After learning about WEFIC's R&D challenges through visits to local enterprises, he immediately thought of connecting them with the Dongying Petroleum Technology and Equipment Industry Research Institute.

Through this partnership, WEFIC collaborated with central enterprises and research institutes, creating a tailored R&D system involving over 10 specialties.

Workers test China's first marine subsea production system at the WEFIC Ocean Equipment workshop in Dongying High-Tech Zone, Dongying city, east China's Shandong Province. (Photo/Liu Zhifeng)

Within a year, the shallow-water subsea Christmas tree went from concept to reality.

The project saw the generation of 1,264 technical drawings and 450 specifications, with every production step executed to exacting standards. Key components, like the tubing hanger, underwent intensive refinement to meet tolerances of less than 0.01 millimeters, supported by expert guidance from the research institute.

On July 17, 2022, China's first self-developed shallow-water subsea Christmas tree system was successfully put into operation in the Jinzhou waters of the Bohai Sea. (Photo/CGTN)

On July 17, 2022, China's first independently developed shallow-water subsea Christmas tree system was successfully put into operation in the Jinzhou waters of the Bohai Sea. The natural gas buried more than 2,000 meters underground was stably transported through the Christmas tree system, and the daily gas output of a single well was 310,000 cubic meters, which can be used by 1,500 families for one year.

To streamline production, the Dongying Institute played a pivotal role in establishing Shandong's only subsea Christmas tree simulation testing laboratory in 2023. This facility allows all required tests to be conducted on-site, significantly reducing costs and logistical challenges.

Today, WEFIC boasts a "1+N" R&D system and has built the country's deepest subsea system simulation experimental platform. This fully integrated production chain can handle depths up to 1,500 meters. Its market share and delivery capacity have expanded significantly, with production cycles reduced by two-thirds.

Looking ahead, WEFIC is collaborating with the institute on intelligent deep-sea oil and gas equipment, aiming to extend the industrial chain.

"The marine oil and gas sector has vast potential; securing our energy supply will create significant opportunities for us," said Liu Huaguo, vice chairman of WEFIC, as he unfolded a blueprint of new innovations.

Intern Han Yifan contributed to this story.