Rising Tides at Tongzhou Bay, Sailing for the Deep Blue
Recently, the 40,000 DWT semi-submersible vessel ZHI YUAN KOU operated by COSCO SHIPPING Specialized Carriers has successfully transported CNOOC’s “Haiyang Shiyou 166”—China’s largest mobile offshore oil and gas production platform—from Tongzhou Bay in eastern China’s Jiangsu Province. The vessel safely arrived at the designated waters of Weizhou in Beibu Gulf, southern China’s Guangxi Province, and smoothly completed float-over and precision positioning operations for the platform.
Precision positioning is a critical operational term in marine engineering, particularly in offshore oil and gas development. It refers to the high-precision maneuvering and fixation of a jack-up drilling or production platform to a predetermined location at sea, typically required for drilling, workover, or platform installation operations.
The “Haiyang Shiyou 166” platform is the largest, heaviest, and most intelligent self-installing production and processing platform of its kind in China to date. With a total weight exceeding 11,500 tonnes, a length of 85 meters, and a width of 46 meters, the platform integrates 3,953 equipment units and combines core functions including full-process oil and gas processing, intelligent monitoring, and living support. It serves as key equipment for the development of the western area of the Weizhou 10-3 Oilfield.
This operation also marks the first heavy marine engineering operation conducted by a self-propelled semi-submersible vessel in Tongzhou Bay. COSCO SHIPPING & Guangzhou Salvage Heavy Lift Transport Co., Ltd.—a joint venture subsidiary of COSCO SHIPPING Specialized Carriers— acted as the general contractor for this project, coordinating vessel operations and the execution of offshore engineering. The outstanding performance of the ZHI YUAN KOU—including precise position control, excellent stability, and robust wind and wave resistance—laid a solid hardware foundation for this highly difficult transportation and the subsequent precision positioning operations.
