Recently, the semi-submersible heavy-lift vessel Zhi Yuan Kou, operated by COSCO SHIPPING Specialized Carriers, has successfully transported and installed China’s largest mobile offshore oil and gas production platform, Hai Yang Shi You 166, for CNOOC. The unit was delivered from Tongzhou Bay to its designated offshore location in the Beibu Gulf, Guangxi, where float-off and high-accuracy positioning operations were completed.
Weighing over 11,500 tonnes and measuring 85 m by 46 m, the platform integrates nearly 4,000 equipment units. It combines oil and gas processing, intelligent monitoring systems, and onboard accommodation, forming a self-installing production facility. The asset is a key component of the Weizhou 10-3 West Oilfield development and is expected to strengthen regional hydrocarbon output while supporting offshore energy development.
This campaign marked the first heavy offshore transport operation conducted from Tongzhou Bay using a powered semi-submersible vessel. COSCO SHIPPING Guangzhou Salvage led the project as general contractor, overseeing both marine transport and offshore execution phases.
A defining element of the operation was precision positioning, a core offshore engineering process involving the accurate placement of large structures at predetermined seabed coordinates. This ensures proper alignment with subsea infrastructure and is essential for safe installation.
Prior to departure, the project team carried out detailed route planning based on meteorological and oceanographic analysis. Operational procedures—including cargo securing, ballast control during submerging and deballasting, navigation monitoring, and final positioning—were refined through simulations and emergency drills.
During transit, the vessel maintained strict navigational control under variable sea conditions. Continuous monitoring ensured cargo stability, while speed and heading adjustments mitigated the effects of currents and weather changes.
Upon arrival at the Weizhou field, the team completed float-off, towing, and final installation with high accuracy, achieving seamless integration between the platform and its subsea structure. The successful execution underscores the vessel’s stability and positioning capability, as well as the operational expertise behind complex offshore transport and installation projects.
The deployment of Hai Yang Shi You 166 represents a significant step in advancing offshore production capacity in the Beibu Gulf and reinforces the role of large-scale marine engineering in supporting national energy security.
According to the latest data from a ship tracking service, the vessel has departed Beihai and is currently en route to Exmouth Port, Australia.
Source: CNSS
