Haiji One, Asia's first 300-meter deepwater jacket designed and built independently by China National Offshore Oil Corp, finished construction on Friday, said the country's top offshore oil and gas producer, CNOOC.

A jacket serves as the foundation of the offshore oil and gas platform. Used to support the huge body and tonnage of an offshore platform, it is the most widely used in offshore oil and gas development equipment globally.

The project is expected to be put into operation during the second half of this year to serve the Lufeng 15-1 oil field platform located in the South China Sea.

As a major breakthrough in jacket design and a milestone in the construction of a super large offshore oil and gas platform in China, Haiji One will further improve the country's energy supply and guarantee China's energy security.