The main goal of current mooring design codes on the Norwegian shelf is to survive a 100-year storm. The consequence is often poor operability for drilling operations and significant fuel consumption with associated emissions. This article presents an alternative philosophy where the mooring system is optimized for drilling operations and disconnected during high sea states, while maintaining the required safety level.

The release of the mooring system is activated by RAR Plus, a mooring component inserted into the mooring line. The component can be released using both hydroacoustic and mechanical release mechanisms.

A case study has been developed using the COSL Promoter on the Statfjord field, where the new design philosophy is compared to the current method. The study includes differences in mooring equipment, anchor handling vessel requirements, fuel consumption, and CO2 emissions.

The main findings from the case study show a 50% reduction in the number of anchor handling vessels per mooring operation, as well as a significant reduction in fuel consumption and CO2 emissions for positioning. Given the expected shortage of anchor handling vessels in the coming years and the push for greener operations, the new design philosophy is highly relevant for the future, as it will contribute to greener, safer and more cost-effective drilling operations.