By James Davies, Head of Turbomachinery Services at Sulzer.
In November 2025, the UK Government released its North Sea Future Plan, bringing renewed focus to an industry that contributes around £20 billion annually to the UK economy. One component of the plan was the introduction of Energy Transition Certificates that will allow drilling in oilfields where production takes place on, or close to, existing fields and is tied back to platforms using existing infrastructure. This shift places these offshore assets firmly in the spotlight.
At the heart of much of this infrastructure sit aeroderivative gas turbines, adapted from aviation technology and embedded into offshore platforms decades ago, which remain critical to safe and continuous operations. But as they age, operators are facing mounting challenges around reliability, availability and cost.
With the average age of North Sea platforms around 25 years – and many significantly older – operators are increasingly reliant on legacy equipment that cannot be easily replaced. This creates a complex balancing act: maintaining uptime and operational integrity while avoiding spiralling costs and prolonged downtime. In this operating context, these challenges can be overcome by repairing parts for that equipment rather than defaulting to replacing them, which is becoming a riskier option due to uncertain supply chains and higher costs.
Built to last, but not to replace
Much of the North Sea’s infrastructure was built using the best available technology at the time – often dating back to the 1970s. However, unlike some of the other equipment on an offshore platform, operators are often unable to fully replace or reconfigure core turbomachinery such as gas turbines, which are deeply built into platform designs, with piping, auxiliaries and structural elements formed around it.
Doing so would require extensive redesign and reconfiguration, making it both economically undesirable and operationally impractical. As a result, operators must continue to rely on ageing equipment to power critical functions from processing hydrocarbons to supporting safety systems.
To put this into context, imagine you bought a state-of-the-art car years ago, which has now become less economical to run. While newer models may now be more efficient and cost-effective, replacing it entirely may not be financially viable for you right now. Instead, the focus shifts to maintaining and optimising it – investing in the car’s efficient operation and reducing the risk of a breakdown that could leave you stranded.
Supply chains under pressure
These challenges are compounded by increasing strain on global supply chains. For many legacy gas turbine models, original equipment manufacturers (OEMs) have shifted focus onto newer technologies, reducing or ceasing production of older components altogether.
Even where parts remain available, supply chains are complex and fragile – especially given current trade winds. Gas turbine components, such as blades, often involve multi-stage, cross-border manufacturing processes: critical minerals may come from Australia, casting takes place in one part of Europe, while machining and coating follow in different parts of the continent. All it takes is one disrupted stage of the supply chain to delay the delivery of the blade. For aging gas turbines in particular, this creates a growing risk to operational continuity, as delays in sourcing critical components directly impact uptime.
On top of those risks, gas turbine operators in the North Sea are effectively competing with demand across fast growing areas from data centres to defence. Take the critical minerals that are essential for hi-tech military hardware; when global governmental spending increases at the 37% rate it has between 2015 and 2024, there is a risk of turbine blades and other gas turbine parts for the oil and gas industry being pushed down the pecking order. Nevertheless, that will be no consolation for operators who are experiencing 18-month lead times for turbine blades, which could hamper gas turbine availability and threaten the profitability of production.
Repair as a lever for reliable operations
Fortunately for operators, there is often a more efficient and cost-effective alternative to ordering new parts. For gas turbines, non-rotating parts don’t typically experience limitations in lifetime due to operational environments, so can be repaired indefinitely given proper inspection and quality-controlled repair processes.
Even for rotating parts, which are at risk of fatigue, there is often an opportunity to repair; particularly when those parts are being closely monitored and inspected for signs of defects so action can be taken early to increase their efficiency and mitigate the risk of failure during operations.
By choosing to repair rather than replace parts, operators can cut lead times by 50%, reduce costs by 50% and ensure availability of gas turbines.
The efficiency savings from repairing rather than replacing gas turbine parts are significant. However, it is important to recognise that these approaches are not only specific to gas turbines. Other rotating equipment – such as compressors, motors and pumps – require fundamentally similar maintenance and repair strategies, whilst accounting for differences in design, operation and component construction. The principle remains: repair and overhaul reduce lead times, lower costs and protect availability.
With this in mind, opportunities to improve performance and efficiency exist across the wider platform when equipment is assessed on its own terms. Operators seeking efficiency gains should therefore adopt a holistic approach, undertaking a full assessment of their motors, compressors, mechanical drives and pumps to ensure parts are performing effectively.
For example, one of our customers faced a performance issue with its gas compression system on a platform where the typical process would be to replace the high-pressure (HP) and low-pressure (LP) compressor bundles, which can be time-consuming and costly. Following in-depth technical assessments, we proposed an alternative of a targeted rerate of just the LP compressor bundle, which reduced the project time by 12 months and saved our customer millions of pounds in capital expenditure.
To take a different piece of equipment, research has found 33% of pumps in upstream oil and gas production run outside of the preferred operating region for more than 80% of the time. In practice, that means 18% of those pumps have potential operational savings of over $50,000. Therefore, operators who regularly assess the performance of equipment on their platforms holistically will save more than those who don’t.
Finding efficiencies
The UK Government’s announced Energy Transition Certificates enabling tie backs to existing infrastructure should prompt operators to review their platform infrastructure to ensure it is running as profitably as possible.
Gas turbines will remain central to offshore operations, particularly as operators look to extend asset life and maintain performance. At the same time, many of these broader pressures also apply across other critical rotating equipment, including compressors, pumps and motors – highlighting the need for tailored maintenance, repair and lifecycle strategies across the entire platform.
Where replacement may once have been the default option, operators should now prioritise repair – improving profitability and extending the life of critical assets in an increasingly cost-constrained and supply-challenged operating environment through repair, optimisation and targeted intervention.
In the North Sea, success will come down to how operators extract value from assets they already have, not how quickly they replace them.
James Davies, Head of Turbomachinery Services at Sulzer
