An 83-metre-high steel tower used by Woodside to produce oil at a long defunct project is sinking, prompting concerns it could damage the marine environment around Western Australia’s Ningaloo Reef.
Offshore regulator National Offshore Petroleum Safety and Environmental Management Authority (Nopsema) has directed Woodside to mitigate risks the tower – called a riser turret mooring (RTM) – poses to the environment and vessels in the area.
Australia’s biggest listed oil and gas company also needs to report on its decommissioning plans for the structure, according to the notice issued in late December first reported by WA Today.
Turret moorings are used in offshore oil and gas projects to secure floating production storage and offloading vessels.
Weighing more than 2,500 tonnes, Woodside’s structure likely contains toxic chemicals and has degraded to such an extent since the project ceased in 2018 that towing it to shore could cause significant damage.
The issue brings into focus the responsibilities companies have to clean up oil and gas fields and clear them of all equipment after projects have been decommissioned.
A Woodside spokesperson said in a statement there are plans to increase the structure’s buoyancy early this year, followed by plans for its removal.
“The RTM is planned to be removed at the end of 2023 into early 2024, subject to approvals, weather conditions and vessel availability,” the spokesperson said.
Woodside wants to transport the tower by barge to Henderson, in Perth, for “local recycling or reuse opportunities”.
The tower previously anchored the Nganhurra facility over the Enfield oil field near the Ningaloo marine park north-west of the Western Australian town of Exmouth.
The regulator issued the new directions after it was found in October that the structure was sitting 1.5 metres lower after water leaked into a compartment. It has since dropped further.
The Greens’ healthy oceans spokesperson, Senator Peter Whish-Wilson, said the structure should have been removed when the project ceased operating.
“It is disgraceful and unacceptable that four years have passed with Woodside failing to clean up its mess,” Whish-Wilson said on Thursday.
“We need stronger laws and regulations to govern the decommissioning of these toxic facilities because we know the industry will try to cut costs at the expense of the environment and the taxpayer every time.”
There is a risk it could submerge or sink completely.
“A toxic chemical spill this close to the Ningaloo Reef world heritage area would be devastating for WA’s precious marine wildlife, including thousands of species of whales, sharks, fish, turtles and corals,” Whish-Wilson said.
Ningaloo Reef is one of the longest near-coast reef systems in the world, with parts of it located just a few hundred metres offshore.
The oil project was a financial success for Woodside, with production starting in 2006. The project was expected to close before 2018, but its strong performance meant production was extended.
The floating facility was removed at decommissioning, and wells closed and depressurised. But the removal of the huge tower has been beset by delays due in part to the degrading of the structure.
Woodside has not adequately maintained the tower, and has missed inspections, which has now made towing the turret onshore for disposal a potential hazard, the regulator has previously found.