China's Deep Sea No.1 gas field sees key construction progress

Deep Sea No. 1, China's self-developed ultra-deep-water gas field, has seen the onshore manufacturing of its integrated processing platform completed and the platform's jacket put under the sea recently, China National Offshore Oil Corporation (CNOOC) said on Thursday.

The integrated processing platform, made of an underwater jacket and a production module over the sea, is about 136 meters tall and weighs approximately 12,215 tonnes, heavier than 8,000 cars.

The jacket with eight legs and 12 skirt piles was completed onshore in Shenzhen of south China's Guangdong Province in mid-January. The offshore production module owns a 57.5-meter-long and 36-meter-wide deck.

"The platform is equipped with multiple sets of domestically produced equipment with full independent intellectual property rights, including a 7-megawatt combustion turbine generator," said Guo Qing, general contract manager of the Deep Sea No.1 Phase II Project.

"It is also equipped with the country's largest offshore platform slug flow catcher independently developed by CNOOC, which is used to eliminate the risk of liquid level fluctuation and blockage of oil and gas mixed transport pipelines and ensure the reliable operation of oil and gas treatment equipment," Guo said.

The project's jacket was recently placed into the target position under the sea area near Sanya of south China's Hainan Province and will be assembled with the production module over the sea in mid-February.

Jacket platforms are the world's most widely used offshore oil and gas production facilities and serve as the base of the entire gigantic oil and gas production platform over the sea. The Deep Sea No.1 Phase II Project jacket weighs over 6,605 tonnes and is 100.8 meters tall – almost the same as a 36-story apartment building.

"The Deep Sea No.1 Phase II Project's jacket offshore installation was done by the slideway launching method," said Li Shilong, chief technician of offshore jacket installation for the phase II project.

"This method uses the jacket's own gravity and cooperates with the hydraulic jack to help the jacket slide smoothly into the sea from the barge, and then the jacket is hoisted and set on the bottom through the crane ship so that it will be installed right in the place," Li said.

(Cover image: An aerial shot of the Deep Sea No.1 Phase II Project jacket, Shenzhen City, south China's Guangdong Province. /CMG)