The Australian oil and gas company Woodside has removed the Nganhurra Riser Turret Mooring (RTM) from the Enfield field, located approximately 52 km northwest of Exmouth in Western Australia.
According to Woodside, the RTM has been lifted onto a barge off North West Cape in Western Australia and is now transiting to the Australian Marine Complex (AMC) near Perth, where it will be cleaned and deconstructed in preparation for recycling and reuse.
"In a world-first, the heavy lift vessel Heerema Aegir, with three supporting tugs, lifted the 2,500 tonne RTM onto a 120m 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," Woodside said.
The Nganhurra RTM is about 83 meters long and brought subsea production lines from the Enfield oil field to a floating production storage and offloading facility. Enfield ceased production in November 2018 and the RTM is being removed as part of decommissioning activities at the field, which also includes the permanent plugging and abandonment of 18 former production wells.
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 remotely operated vehicle inspections, the 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. After the RTM is unloaded at AMC, it will be cleaned of marine growth and deconstructed for recycling and reuse opportunities, supporting local employment and contracting opportunities. More than 95% of the Nganhurra RTM will be recycled or re-used," Woodside said.
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