Allseas begins prep work for Australia’s ‘largest-ever’ offshore decommissioning job

Allseas has begun the planning and preparation for what it says is the largest-ever offshore decommissioning assignment in Australia, encompassing the removal of up to 12 retired platforms.

Allseas has been appointed by Esso Australia, a subsidiary of ExxonMobil Australia, to remove 12 topsides and up to 11 steel jackets from the Gippsland Basin in the Bass Strait, together weighing approximately 60,000 tonnes.

Work has already begun, with engineering and project management teams in Perth and Melbourne at the lead, and support from the company’s offices in Delft, the Netherlands, and Kuala Lumpur, Malaysia.

According to Allseas, the contract will see the giant heavy lift vessel Pioneering Spirit for the first time take its single-lift technology to Australia. The capability allows the removal of entire offshore structures – topsides and jackets – in one go, allowing the completion of this scope in just a few months.

The plan is to remove all the structures in 3 to 4 months, starting in late 2027. Once removed, the facilities will be transferred to barges or vessels for load-in to the Barry Beach Marine Terminal in Victoria for dismantling and recycling by a separate onshore contractor.

“This landmark decommissioning project represents a significant milestone for Allseas in Australia,” said Evert van Herel, General Manager Allseas Australia. “Over the past 20 years, we’ve built a strong track record delivering subsea pipelay and construction services for major greenfield projects in these waters. It’s an honour to now bring our expertise to the first removal of platforms of this scale from Australian waters.”

Of note, Allseas this summer removed the fourth and final platform from Shell’s Brent field in the UK’s North Sea using Pioneering Spirit in single-lift removal, described as the heaviest offshore lift ever performed.

Most recently, the company announced it was bidding farewell to a shallow-water pipelay barge it purchased in 1997, after having it used for installation of over 400 kilometers of nearshore pipeline across the world.