China's first ultra-deepwater gas field Shenhai-1, or Deep Sea No. 1, achieved significant progress with all three subsea production facilities successfully installed for Phase II of the project, according to China National Offshore Oil Corporation (CNOOC) on Tuesday.

The homegrown Shenhai-1 is a deepwater subsea multipurpose system for the development of the deepwater oil and gas reservoirs under high temperature and pressure.

The newly-installed systems, the underwater manifold centers, are one of the core equipment for the development of deepwater oil and gas fields, often referred as underwater "oil and gas hubs". They are used to collect and transport the oil and gas produced by underwater wells.

Weighed over 540 tonnes in total, the three systems are the heaviest equipment among underwater production facilities. The installation faced multiple challenges such as extremely high hydrostatic pressure, unstable ocean currents as well as dark seabed conditions.

Gao Xuanpeng, deputy general manager of the Phase II project said the installation is taking place during the season of sea typhoons, with complex and changeable climate and sea conditions, posing great challenges to the installation operations. "Our team has overcome technical challenges such as wire rope torsion during installation, setting a new record in depth for double-rope hoisting operation in China's marine engineering."

Located in the western part of the northern South China Sea, the Phase II of the Shenhai-1 is approximately 130 kilometers off the coast of Sanya City in Hainan Province.