US supermajor Chevron completes technically challenging decommissioning with ‘significant milestone’ in Australia

Chevron has completed onshore decommissioning works at Thevenard Island, hailing it as a “significant milestone” for Western Australia’s emerging decommissioning industry.

Meanwhile, decommissioning of the Chevron Australia-operated Barrow Island joint venture oil facility and associated infrastructure on Barrow Island, which hosts the Gorgon liquefied natural gas project, is expected to begin in 2025.

“Decommissioning is an enormous economic opportunity that will grow as existing assets enter the later stages of their life cycles,” said Chevron Australia’s director of operations, Danny Woodall.

The Thevenard Island decommissioning process involved the plugging of 11 onshore production wells, three water disposal wells and one exploration well.

It also included the safe dismantling and removal of three 150,000-barrel oil storage tanks in addition to production tanks, separator vessels, flowlines, associated process infrastructure and ancillary accommodation facilities and utilities including the controlled toppling of the 38-metre communications tower.

In total, the project resulted in the removal of more than 5000 tonnes of metal from the island for recycling.

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The US supermajor said the project was logistically complex given the remote nature of the island, and technically challenging given Thevenard Island is a nature reserve, and the area is next to a tourism operator.

First explored in the late 1960s, Thevenard Island has been home to the Chevron-operated Thevenard Island joint venture oil and gas facility located about 22 kilometres from Onslow. The facility began producing oil in 1989, with about 150 million barrels of oil produced over its 25-year life until nine years ago.

The area will be returned to the Western Australian government once it is restored to a condition similar and compatible with the surrounding environment.

Chevron Australia’s Thevenard Island Retirement Project manager Chris Jones said the project “is an example of Chevron’s commitment to progressing decommissioning and rehabilitation activities in a systematic and timely manner to deliver positive outcomes for the environment and local community”.

Chevron Australia engaged contractors including Liberty Industrial, AGC, Bhagwan Marine, TAMS Group, Golder Associates and Astron Environmental Services to assist with the decommissioning process.

Liberty Industrial general manager Barry Crossey said that Thevenard Island set a new benchmark for transforming end-of-life sites into rehabilitated areas, that can be carried through to future projects in the region and further afield.

“As we celebrate this achievement, we also reflect on the lessons learned throughout the process and are committed to using these insights to further refine and improve our operations, increase efficiencies and set new safety and environmental standards within the industry,” Crossey said.

The rehabilitation process also included working with local partners NTC Contracting, Workpower and the Onslow Indigenous Sea Rangers to plant more than 120,000 native seeds — supporting local jobs and businesses in the process. Monitoring of rehabilitation will be carried out over the next few years, Chevron added.