Haikou, China, 03 May 2024 (Xinhua)

China's first independently-developed and built ultra-deepwater gas field, Shenhai Yihao, or Deep Sea No.1, has recorded an accumulated natural gas output of over 8 billion cubic meters so far, with its oil output exceeding 800,000 cubic meters.

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

Deep Sea No 1 is the world's first 100,000-ton deep-sea semi-submersible oil production and storage platform, which is independently developed and constructed by China. It was put into use on June 25, 2021. After two years of operation, the platform had produced over 5 billion cubic meters of natural gas.

According to the China National Offshore Oil Corporation (CNOOC), its operator, the construction of the phase II project of Deep Sea No. 1, which aims to upgrade the gas field, is underway. Upon completion, it will control 23 deep-water gas wells and two sets of underwater production systems.

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

Cleaning and inspection of condensate tanks under deep sea is extremely hard, and completing of the task is a milestone that underscores the exceptional reliability and cutting-edge design of the pioneering platform, expert noted.

Deep Sea No 1 is equipped with four condensate storage tanks with a single capacity of 5,000 cubic meters, which are designed to safely store condensate oil separated during the process of deep-sea natural gas extraction. They are one of the three world-class innovative technologies integrated in the Deep Sea No. 1 gas field.

Condensate tanks of Deep Sea No 1 are over 48 meters deep, and they are the deepest and most intricate tanks among China's offshore oil and gas facilities. As natural gas condensate is highly volatile with a low flash point, and being insoluble in water, cleaning and inspection of the tanks are extremely dangerous, Li Zhi, a manager of Deep Sea No 1, was quoted as saying.

To ensure its safe operation, working teams at Deep Sea No 1 emptied the condensate tanks, developed an implementation plan and risk response strategy before cleaning and inspection, and built customized personnel baskets to facilitate the safe entry and exit of operators.