Floating production systems

CNOOC Launches World’s First Ultradeep Semisub Production and Storage Platform

With all critical components nearly in place, production is set to start this year at the Lingshui 17-2, China’s first ultradeepwater gasfield development project.

CNOOC Deep Sea No. 1.jpg

The world’s first deepwater semisubmersible production and storage platform has been launched at the Lingshui 17-2 gasfield development project, located in water depths of 1500 m in the northern South China Sea.

Situated in the northern part of the Qiongdongnan Basin in the western continental shelf (WCS), the Lingshui 17-2 is approximately 150 km south of Sanya, Hainan province.

Operator China National Offshore Oil Corporation (CNOOC) will now begin installation and commissioning on the platform, Deep Sea No. 1.

The China-built platform has a maximum oil storage capacity of nearly 20000 m³ of condensate for ship-to-ship offloading and was built to ABS Class quality and safety standards. It weighs more than 50,000 tons and has a maximum surface displacement of 110,000 tons.

Production from the field is scheduled to start this year; gas from the development will be piped to Hong Kong for power generation via an existing pipeline originating on the Yacheng 13-1 field.

Lingshui 17-2 will supply 3 billion m3 of deep-sea natural gas to Guangdong, Hong Kong, and Hainan every year. It will meet one fourth of the local gas demand in Guangdong-Hong Kong-Macao greater bay area.

Components of the development include a subsea production system (initially comprising 11 subsea trees tied back to the semisubmersible platform via four manifolds), subsea pipelines, two 10-in. steel catenary production risers, two 12-in. production risers which connect the subsea pipelines to a semisubmersible production facility, and two 18-in. steel catenary risers connected to a 95-km gas export pipeline. It has eight separate gas reservoirs, each with between one and four gas layers with an average thickness of 293.3 m.

At least four major companies have been instrumental in various phases of field construction.

In October 2019, Singapore-based MacGregor, a unit of Cargotec, a Helsinki cargo and load-handling solutions firm, was selected to supply the on-vessel mooring systems and riser pull-in system for the development’s deepwater floating production unit (FPU).

Two months later, Malaysian offshore projects and services provider Subsea 7 was awarded a contract to install steel catenary risers for the project.

In June 2020, Allseas began its own part in the development, marking the Swiss company’s first contract vessel job in China. The engineering and design firm’s pipelay vessel Audacia installed some 160 km of subsea pipelines and multiple structures, with Calamity Jane providing the support.

Last fall, Texas technology company Oil States Industries was chosen to complete the design of FlexJoint flexible connectors, receptacles, mockup tools, and cross-haul tools for the project.

Operator CNOOC holds 51% interest in Lingshui 17-2; Shell holds 29% and Canada's Husky holds 20% interest.