NOPSEMA has accepted Santos’ plans for final seabed decommissioning activities at its Mutineer Exeter oil fields off the coast of WA.
The project’s Cessation of Production Environment Plan enables the continued operation of the Mutineer, Exeter, Fletcher and Finucane facilities in cessation phase and the removal of floating assets. With the latest approval from NOPSEMA, it will now also include final seabed decommissioning activities within WA-54-L, WA-26-L and WA-27-L.
The permit areas are within Commonwealth waters, approximately 160 km north of Dampier, in water depths ranging from 130–160m.
The scope of decommissioning work for this Environment Plan includes:
– removal of floating asset (DTM and MWAs) from the title area
– removal of subsea equipment normally located on the seabed during production
– decommissioning and abandonment in situ of select subsea equipment normally located on the seabed during production consisting of:
– two steel, epoxy coated gravity bases complete with concrete ballast weighing about 330t each set) and their associated tether chains
– Six deeply buried steel anchors and the six corresponding steel mooring chains of approximately 710m and roughly 190t per mooring leg.
Individual inspection, monitoring, maintenance, repair campaigns may take approximately 14 days with floating asset removal activities estimated to take up to 45 days in the operational area.
Decommissioning of the seabed assets may take up to 12 months cumulative duration. However, unfavourable weather and operational delays this could extend the estimated project durations.
Decommissioning is expected to commence in H2 2024 and will be completed by end 2025.
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