China's first independently developed and independently built ultra-deepwater gas field, Shenhai Yihao, also known as Deep Sea No. 1, has recorded an accumulated natural gas output of over 9 billion cubic meters to date, with an oil output exceeding 900,000 cubic meters.

Shenhai Yihao, the deepest gas field of its kind in China, began operation on June 25, 2021.

The China National Offshore Oil Corporation (CNOOC) has said that once its phase II project, which aims to upgrade the gas field, is fully operational, it expects that Deep Sea No. 1 will increase its peak annual output from 3 billion cubic meters to 4.5 billion cubic meters. And by that time, the gas field will be an important gas source for the country's energy security.

The phase II project has proven natural gas reserves of over 50 billion cubic meters, and includes such facilities as 12 deepwater gas wells, a comprehensive processing platform weighing over 14,000 tonnes, and five submarine pipelines with a total length of approximately 250 kilometers.

Deep Sea No. 1 is located 150 kilometers from the city of Sanya in south China's island province of Hainan. It is able to operate at a maximum marine depth of over 1,500 meters.