Unmanned surface vessels (USVs) have gained growing interest across maritime industries in recent years. Though still in the early stages of deployment, they pair more sustainable fuel systems with greater efficiency and agility – without the need for crews on board.

The North Sea is proving an ideal test bed for the technology, and the hope is that these solutions can ultimately reduce carbon emissions and costs, while enhancing safety.

These remotely and even autonomously controlled seaborne robots have already demonstrated their capability. Fugroâ€™s Blue Robotics division has developed its Blue Essence USV – equipped with its own smaller remotely operated vehicle (eROV) called Blue Volta, capable of diving up to 450m. The craft can spend up to two weeks conducting offshore inspections without the need for refuelling.

Still at the cutting-edge, Blue Essence is the first USV to get approval from the Maritime and Coastguard Agency (MCA) to carry out underwater UK surveys and operate remotely with an eROV.

In a world first, Blue Essence completed a fully remote offshore wind inspection at Aberdeen Bay Wind Farm last year. After launching from Fugroâ€™s remote operation centre (ROC) in Aberdeen, the vessel inspected wind turbine structures for their stability and safety, while creating a detailed seabed map using a deep water multibeam echosounder sensor on its hull. The real-time geodata helped Vattenfall, who part-funded the wind farm, make asset management decisions quickly.

Blue Essence undertaking remote inspection of Aberdeen Wind Farm. Source: Fugro

Situated just 3km off the east coast of Aberdeenshire, the farm is an ideal testbed for the technology â€“ though more complex operations are possible.

Blue Essence was also deployed last year to complete Fugroâ€™s first remote offshore survey inspection in the North Sea. Deployed on behalf of oil and gas producer TAQA, the project involved inspecting two platforms and over 40km of pipeline from the coast of the Netherlands. Here Fugro says the focus was on seabed mobility, pipeline depth and visual inspections to assess the integrity of TAQAâ€™s assets.

The USVs were controlled remotely via satellite link by operatives at the Fugro ROC in Aberdeen and the Netherlands, with geodata sent back to shore informing on offshore assets and seabed environment.

Benefits of adoption

â€œAutonomous and remote solutions significantly reduce the total health, safety, security and environment (HSSE) exposure,â€ says Fugro Blue Robotics director Henk van Dalen.

â€œUsing traditional survey vessels, crews are exposed to harsh and sometimes unpredictable marine environments but now we have the capability to conduct the most difficult tasks autonomously, hugely decreasing the risk to personnel.â€

Saving time also saves money, and having professionals work onshore from Aberdeenâ€™s ROC – as opposed to miles into the North Sea – provides a safer working environment.

Carbon emissions are increasingly a major consideration. Mr van Dalen mentioned that by using smaller vessels or hybrid fuel systems, USVs can cut fuel consumption and emissions dramatically compared to conventional ROV support vessels.

â€œWith small and hybrid vessels, we can reduce fuel consumption by up to 95%, which in turn means a large reduction in the carbon footprint of our operations. As this transition to smaller, more eco-friendly vessels continues, the environmental benefits will also increase.â€

He says more than 1,400 tonnes of marine diesel have been saved in their North Sea operations alone.

As marine environmental standards tighten, solutions like these may increasingly be an economic choice as much as an environmental one.

But solutions like Blue Essence suggest USVs could speed up offshore operations more generally. Time is saved on logistics avoiding sending personnel to sea, as well as modern cloud-based processing and data delivery faster than ever.

â€œFinally, there is the data collection itself. The new capabilities allow for faster insights which supports more effective decision making, with data available in near real-time,â€ Henk added.

In a harsh environment like the North Sea, the use of eROVs and USVs also offers the potential for increased weather windows allowing year round operations for some tasks. That points to efficiency gains, but is likely to be of particular interest to the emergent floating wind sector, which will moor in more distant and inaccessible locations to harness bigger yields, but also must tackle with the challenges of reaching them should emergency inspections be required.

People, powered

There are implications for the workforce too, in potentially reducing the overall population of personnel required at sea. Fugroâ€™s USVs, for instance, can be controlled from ROCs which can be located anywhere in the world.

This could free up teams and alter how they work. â€œBy enabling personnel to transition from offshore to onshore roles, organisations can better optimise their teams and build a future workforce with more diversity and new skillsets and competencies,â€ van Dalen explains.

More time could be spent on analysis and insights rather than spending that time on manual tasks at sea, or in supporting an offshore crew, for instance.

â€œRemote technology allows technicians to prioritise more complex analytical tasks rather than devote the majority of their time to support the delivery stages. This leads into another advantage: increased output and accelerating the pace at which insights are received.â€

Blue Essence ROC in Aberdeen. Source: Fugro

Crucially, he says, this is not a case of automation or robotics replacing jobs. For North Sea operations, USV innovations can free up time, allowing more thought to be given to tasks, while potentially saving money. The data they provide could enhance operations and insights for skilled industry professionals, while providing a safer working environment.

â€œStaff that make the transition from offshore to onshore still have a crucial part to play in analysing the raw data collected and converting it into useful client information, presenting expert analysis and recommendations within as little as one hour,â€ van Dalen said.

Commercial contracts

Another group working at the forefront of the field is USV AS, a joint venture between offshore survey firms DeepOcean, Solstad Offshore and Ã˜stensjÃ¸.

Having worked on a concept development since 2018, last year the consortium commissioned their first vessel from shipyard Astilleros Gondan, with a design specifically aimed at subsea inspection, maintenance and repair and targeted primarily at offshore wind farms.

Measuring some 24m long and 7.5m wide, the craft is powered by a hybrid diesel-electric propulsion system, which includes a battery package from Seam. This allows it to work offshore for up to 30 days without the need to be refueled or recharged.

It too is accompanied with a daughter ROV, capable of diving to 1,500m depth, with the whole spread able to be controlled from an onshore base.

As with Blue Essence, USV AS says the blueprint could reduce CO2 emissions by 90% compared with a conventional offshore vessel used for equivalent subsea missions.

Commenting on its development, Solstad CEO Lars Peder Solstad said the vessel concept would represent â€œa step change in offshore operations.â€

The first unmanned vessel ordered by USV AS – a joint venture of DeepOcean, Solstad Offshore and Ã˜stensjÃ¸.

Delivery of the vessel is expected by the end of 2024. Following offshore testing, the partners expect it to be ready for operations in 2025, at which point it would be operated under long-term charter by DeepOcean itself.

The industry is already taking note. In October, Aker BP announced plans to use the craft for subsea inspection, surveys, repair and maintenance, intending to deploy the unit offshore in 2025 on an 8-year charter agreement.

Jarle Marius Solland, Aker BPâ€™s operations manager for subsea execution and survey added: â€œOnce the USV is constructed, tested and ready for offshore operations, Aker BP look forward to utilising it on our subsea fields.

â€œIt is a smart solution that enables us to deploy well-known subsea technologies, but without bringing a large vessel or an unnecessary amount of personnel offshore.â€

The hidden, digital side of USVs

Behind the scenes, USVs will add to the increasingly digital view of the basin, whether that be the maps, GIS visuals, geodata or remote video footage collected while on operations.

USV advances mean surveys of the seabed and subsea facilities are already becoming more detailed, but in future, artificial intelligence (AI) and augmented reality (AR) could contribute to vivid 3D visualisations.

â€œDigital transformation may not be an optional choice for the oil and gas industry in the near future, but it will be definitely a necessity,â€ writes Salam Al-Rbeawi in a recent peer-reviewed article. In particular, he suggests that the use of USVs in hydrocarbon exploration and production will help accelerate seismic interpretation and geophysical study by reducing uncertainties.

Al-Rbeawi points out that USVs have potential to perform diagnostics to monitor pipelines that stretch thousands of miles across harsh environments. Improved diagnostics and visualisations in the challenging North Sea may help companies achieve environmental compliance throughout the energy transition, whether it be for environmental risk assessment or leak detection.

As technology improves, new milestones are being reached with regularity. In November, a small USV built made by UK firm AutoNaut and deployed by SAMS successfully recovered scientific data from a sensor moored at 1,800m deep in the Rockall Trough â€“ another world first.

The USV was deployed, and collected data from Sonardyne Fetch AZA bottom pressure recorders (BPRs), before sending it back to oceanographers on shore via satellite.

Hailed by the project leaders as â€œa major milestone for oceanographyâ€ it also marks a significant achievement in net-zero marine data acquisition â€“ though more are sure to follow.

USVs are unlikely to ever replace crewed vessels needed for operations and maintainenance (O&M) of offshore wind farms, for example – but for rapid data gathering and long-term monitoring, they are fast becoming a no-brainer.

Offering greater efficiency in the form of improved data, diagnostics and insights, they should also help safeguard personnel.

And with designs now opting for electrification or hybrid fuel systems as standard, these craft are also well positioned to make a major impact in reducing carbon emissions, as evidenced by the likes of Fugro and DeepOcean.

Expect to see more commercial contracts in the coming years, and larger and more capable craft taking on ever more complex challenges as the technology develops.

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