An FPSO is a floating vessel used by the offshore oil and gas industry for the processing of hydrocarbons and for the storage of oil or natural gas. The unit has been independently designed and will be fabricated in China, CNOOC said.

The project will further facilitate China's independent design and construction of ultra-large deepwater offshore oil and gas equipment, CNOOC said.

With a daily crude oil processing capacity of almost 6,000 cubic meters, the floating production storage and offloading unit has a maximum crude storage capacity of 60,000 cubic meters, said Liu Huaxiang, general manager of CNOOC's deepwater engineering construction department in Shenzhen, Guangdong province.

With a designed life of 30 years, the unit can operate offshore for 15 years in a row and will be capable of maintaining operations even during super typhoons, Liu said.

China currently operates 18 such facilities, with both the number and total tonnage topping world rankings, CNOOC said.

Together with a deepwater jacket platform, the FPSO upon delivery will serve both the Liuhua oilfield, the country's first deepwater oilfield, and China's largest offshore reef limestone field that started operations in 1996.

The technologies to be applied in the project construction will fill certain gaps in China's offshore engineering sector.

Li Ziyue, an analyst with BloombergNEF, said CNOOC's oil and gas production will rise more than 6 percent each year during the 2022-24 period, as China has seen continuous upstream investment and production commitment in recent years.

The Qingdao facility will play a critical role in enhancing the country's energy supply security. It is proof that China has the capacity to build and assemble internationally advanced super-large FPSO units, Li said.

Compared with traditional ship-type FPSO units, the cylinder-shaped ones consume less steel with better stability to operate in adverse offshore conditions. They also require lower engineering investment and offer better economic applicability, said CNOOC.

Ever since 2007 when the world's first cylinder-shaped FPSO was put into operation, its design has been monopolized by overseas companies. Of the more than 160 FPSOs worldwide, only six cylinder-shaped ones were put into operation in offshore regions, including the United Kingdom, Norway and Brazil.

CNOOC has overcome several challenges, including integrated hull design and compact modular space design layout, during the process, the company said.