In the 1970s, the building of huge offshore facilities inspired awe, and now, a new feat is taking place that is just as remarkable – decommissioning it.
This includes the supporting facilities –wells, pipelines, structures, subsea facilities and FPSO supporting them which are no longer required and must be decommissioned as well.
When construction of the Ninian Central Platform was completed in Scotland’s Loch Kishorn in 1978, its scale far surpassed other offshore facilities built previously. At over 600,000 tonnes, it was the world’s largest movable object.
Many more platforms have been built all around the world since then, alongside extensive subsea infrastructure and tens of thousands of wells.
While many facilities have outlived their original 15-30-year life expectancies, an increasing number are now reaching the end of their productive lives. We’ve now to remove them, and in a way that meets far higher safety, health and environmental standards than we had in past decades, while also considering other wider socioeconomic impacts.
It’s a massive task and a big business on a global scale. Globally, an estimated USD 42 billion is expected to be spent on decommissioning up to 2024 alone. In the North Sea, a more mature region, spending on decommissioning is expected to overtake capital expenditure towards the end of the 2020s. In Southeast Asia, it is predicted that more than 200 offshore fields would stop producing by 2030 with total decommissioning costs estimated to range from USD $30 billion to as much as $100 billion. Energy Voice reported that more than USD $40.5 billion of necessary decommissioning work needs to be carried out on Australia’s offshore oil and gas infrastructure, over half of which must be started within the next ten years.
In the past decades, decommissioning of oil and gas assets has faced challenges and controversies. Partly in response to such issues, decommissioning regulations clarifying approval process and stakeholder engagement has been developing globally. IOGP’s Decommissioning Committee has compiled current decommissioning regulations in Overview of International Offshore Decommissioning Regulations – Volume 1: Facilities (IOGP 584) and Overview of International Offshore Decommissioning Regulations – Volume 2: Wells Plugging and Abandonment (IOGP 585). These will be updated on a regular basis.
IOGP’s overviews of international offshore decommissioning regulations, covering well abandonment and topside facilities, are available to everyone in our Publications library. We’ve also produced briefings on the ecology of steel piled jackets and subsea infrastructure and pipeline and gravity-based structure decommissioning processes.
Based on its members’ experiences with decommissioning regimes around the world, IOGP advocate that:
- Decommissioning policies and requirements need to be clear, stable and predictable to allow preparation of credible decommissioning plans and for estimating decommissioning costs.
- The decision-making process for decommissioning planning and approvals must be clearly defined and efficient
- Regulations must allow selection of the most suitable decommissioning option for the asset, considering safety, environment and stakeholder factors
Technologies have been advancing at a rapid pace. Decommissioning centres such as the National Decommissioning Centre (NDC) in Aberdeen and the newly established Centre Of Decommissioning Australia are helping to lead the way.
A lot of the focus is on reducing well decommissioning costs, through new well barriers and rigless abandonment techniques. The NDC is helping to push the development and adoption of advanced well abandonment technologies, from the use of metals that can fluidise then expand when they cool to seal rock formations; to down-hole imaging systems that can assess what is behind well casings thousands of metres beneath the seabed.
Amazing new technologies have been developed to remove offshore structures. The World’s largest Heavy Lift Vessel Pioneering Spirit is capable of lifting 45,000-tonne topsides structures – in June 2020 it lifted the Brent Alpha topsides in 9 seconds – a game changer that has resulted in a significant reduction in offshore manhours safety exposure.
But decommissioning of structures isn’t all just about removal and disposal. Where possible, the industry is reusing facilities, from individual pieces of equipment to entire structures and pipelines, reducing waste and expenditure. A recent example is the reuse of six substructures at the Tyra field redevelopment in Denmark. Reuse can also come in different forms. At least one former rig has been turned into a recreational diving platform and, while not an oil and gas facility, the REM Island offshore structure was built using the same technology and is now a restaurant in Houthaven, Amsterdam.
These are fun ideas. But there are other ways the platforms we’ve used to feed the world’s energy demand could continue to play a role in the energy mix. The UK Government has studied the feasibility of using existing offshore assets for carbon capture, use, and storage (CCUS). Crown Estate Scotland has commissioned a study looking at whether platforms could be reused for low-carbon hydrogen production. Operators are also looking at the potential to use their offshore facilities as accommodation hubs for wind farm workers.
While these options might only be realistic for some infrastructure, they offer exciting new opportunities and a chance for the industry to share its engineering and project management expertise in new sectors.
In some locations, where facilities can’t be reused, they’ve been turned into artificial reefs, such as in Brunei, Malaysia, and the Gulf of Mexico. For many regions this isn’t an option, so the focus is on removing and reusing and/or recycling as much of them as well can. That, in itself, is an interesting challenge, especially when some date back to the 1970s or even earlier.
But we mustn’t forget that, while we’re on the cusp of this new activity, we are still also building new facilities. So there is another opportunity: to transfer the lessons we learn through decommissioning into new designs. Design for decommissioning, to make facilities easier to decommission at the end of their lives. We can pursue the circular economy in what we do from day one.
We’re also not the only ones building offshore structures. While it’s a much younger industry, the offshore wind industry will face a decommissioning challenge in coming decades – perhaps sooner than you might expect. That means we’re learning skills that the supply chain will be able to use to support this industry too, alongside our own work.
Decommissioning is providing exciting opportunities across many fronts. It’s a fertile area for the transfer and learning of new skills. It’s an area where we’re seeing new technologies, a new supply chain and opportunities to exploit our capabilities in safety, engineering, planning and project management in our own and other sectors.