The riser turret mooring system consists of a turret assembly which is integrated to a mooring line fixing the FPSO to the ocean floor.

In February last year, offshore oil and gas regulator ordered Woodside to decommission the system citing repeated failures to "preserve the condition" of the RTM.

The National Offshore Petroleum Safety and Environmental Management Authority  had concerns that an oil tanker could collide with the RTM and cause an oil spill.

This week Heerema announced it had won the contract for engineering, preparation, removal and transport of the RTM.

The service provider plans to lift the structure in one piece onto a large barge and then transport it to Henderson or another port for dismantling and recycling.

Woodside had planned to move it to shore earlier, however the degredation of the RTM meant it was not stable enough. 

It marks the first decommissioning contract awarded to Heerema in Australia.

"Although Heerema has a long history of safely and sustainably removing offshore structures from the North Sea and the Gulf of Mexico, we are very excited to continue our responsible decommissioning operations in Australian waters," Heerema chief commercial officer Jeroen van Oosten said.

"Heerema is looking forward to taking an active role in Australia's decommissioning ambitions. The removal and subsequent reuse or recycling of offshore infrastructure is an essential final step in the lifecycle of oil and gas infrastructure and aligns with our company values of responsibility, sustainability, and contributing to a circular society."

The RTM connected the Enfield oil field in production licence WA-28-L to the Nganghurra FPSO.

It had been on stream since 2016 before being shuttered in December 2018.

Woodside was the operator of the field alongside Mitsui.