Case Study: Nganhurra RTM planning, execution and recycling

In October 2023, the Nganhurra Riser Turret Mooring (RTM) was safely and successfully removed from its location off the North West Cape in Western Australia and transported to the Australian Marine Complex (AMC) near Perth, to be cleaned and deconstructed in preparation for recycling and reuse.

The heavy lift vessel Heerema Aegir, with three supporting tugs, lifted the 2,500 tonne Nganhurra RTM onto a 120-meter barge where it was secured ahead of its journey to the AMC. The removal of the RTM is a significant milestone and further demonstrates Woodside’s ability to manage activities in the sensitive marine environments where we operate. The RTM is about 83 meters long and brought subsea production lines from the Enfield oil field to a Floating Production Storage and Offloading facility.

The decommissioning concept for the Nganhurra RTM was matured over more than two years of careful planning and detailed engineering, undertaken in conjunction with a range of specialist contractors. In-field preparatory activities included Remote Operated Vehicle inspections, removal of redundant equipment and installation of a purpose-built lifting point. Following an assessment of the forecast weather and sea-state, the remaining mooring lines were cut, and the RTM was towed to a sheltered location to ensure the lifting operation could be executed safely.

At the AMC, the Nganhurra RTM was cleaned of marine growth and is progressing deconstructing for recycling and reuse opportunities, supporting local employment and contracting opportunities.