Leveraging our decommissioning experience

As we begin the extensive planning that will be required to decommission our non-producing platforms in Bass Strait, we’re working to fully leverage our company’s substantial experience and expertise which has seen us safely and effectively decommission assets across the globe.

While there may not be many examples of offshore decommissioning activities close to home, if you look a little further afield you will find some great examples where ExxonMobil has successfully decommissioned assets while achieving positive outcomes for communities and the environment.

Our Australian decommissioning team is using learnings from our experiences in other locations, and liaising closely with our decommissioning centre of expertise, to ensure our local decommissioning activities will meet regulatory, community, government and importantly, our own, high expectations.

“ExxonMobil’s approach to decommissioning assets varies depending on the type of structure and unique characteristics of a specific site,” said ExxonMobil Australia Chairman, Nathan Fay.

“We incorporate best practices from other projects and expert advice from relevant stakeholders, including fishing communities, scientific organisations, repurposing and recycling specialists and academia.”

The process of decommissioning an offshore asset presents complex challenges. Decommissioning plans must consider the specific marine ecosystem, the size and weight of facilities and the inherent risks of removing such facilities.

“Planning and preparation for decommissioning assets can start up to 10 years prior to actual execution, which is why we’re starting our detailed planning now,” said Nathan.

“We’ve been closely watching the progress of ExxonMobil’s global decommissioning activities, including two, very different but successful campaigns completed by ExxonMobil this year in Canada and the Gulf of Mexico.”

In July, ExxonMobil created a new reef site in the Gulf of Mexico outer continental shelf when it toppled-in-place the Lena platform jacket, turning it into a deep water reef.

The ExxonMobil team were able to successfully demonstrate to regulators that, as an artificial reef, the Lena will benefit the environment by continuing to provide habitats for rare marine wildlife in the area, which is similar to what we achieved with the Adelaide refinery wharf in South Australia.

“Their success in working with regulators to achieve this outcome is something we hope to replicate in Bass Strait.”

Meanwhile, in November, ExxonMobil Canada reached a key milestone in the decommissioning of its Sable project with the final removal of all seven offshore platforms which had commenced in May after more than eight years of extensive planning and studies. 

ExxonMobil Australia's decommissioning technical team lead, Emma Ogilvie, was the project manager for ExxonMobil’s decommissioning of the Sable project in Canada during the early planning stages.

“At the Sable field, an enormous semi-submersible crane vessel, Heerema’s Thialf, was used to carry out a sequence of separate lifts of platform components, such as topsides and jackets, using a reverse-installation method,” said Emma.

“During this process, an export barge was used to transport five loads of platform components, weighing a total of approximately 48,000 tonnes, across the Atlantic to a disposal and recycling yard in the U.K.”

“Around 99 percent of the material from Sable will be recycled,” she noted. 

“Importantly, Sable’s best-in-class safety performance continued throughout the removals campaign, with the project maintaining its lost-time incident free status for more than 19 years.”

Similarly to the work we’re currently taking out in Bass Strait, the Sable platform removal campaign followed multiple years of well plug and abandonment activities, as well as parallel activities to prepare offshore platforms for removal. 

“This year we’ve made some great progress with our well plug and abandonment work, making safe our Whiting, Seahorse, Tarwhine and Mackerel wells as well as ensuring our platforms remain in a safe state while we continue our extensive planning for their eventual decommissioning,” said Nathan.

While our decommissioning plans for Bass Strait are still very much in the early planning stages, the success of the Lena and Sable decommissioning campaigns demonstrate that our company has the knowledge, expertise, experience and skill to achieve similar success in Bass Strait.

“We look forward to working with our regulators and communities as we work out the best approach to decommissioning our assets in Bass Strait so that we too can achieve beneficial outcomes for all.”

Sources:

Sable Project: https://soep.com/about-the-project/index.html

Lena: Bureau of Safety and Environmental Enforcement | Promoting Safety, Protecting the Environment and Conserving Offshore Resources