Unmanned surface vessels have been tested in the offshore industry for a number of years, but many more autonomous systems – swarms of them – are on the way
Collecting data is essential to designing, building, operating and maintaining any kind of asset in the offshore energy industry, and although unmanned surface vessels (USVs) are still an emerging technology, there has been significant growth in recent months in the number and type of operations completed by them, with energy majors such as Equinor, and developers such as Ørsted, increasingly involved in testing them.
Working with USV developers including Sea-Kit and XOcean, Equinor first trialled USVs in the North Sea offshore oil and gas market in 2019. For a conventional pipeline inspection project, it noted, a remotely operated vehicle (ROV ) support vessel with around 50 people on board would be required. In contrast, for an unmanned pipeline inspection, no vessels or humans at sea would be required. Moreover, a manned vessel would have fuel consumption 12 m3 per day, whereas the fuel consumption of an unmanned unit would be less than 0.15 m3 – a 99% improvement.
Such are the cost savings that can be achieved, even vessel owners and charterers are adopting USVs. Reach Subsea – which currently provides subsea services from a fleet of six vessels – says it sees USVs as the platform of choice in future.
As the company’s chief executive Jostein Alendal explained, a typical current project involves 30-50 personnel on a subsea vessel, whereas with Reach Remote, the USV capability it is developing, the same project can be executed with a much smaller, more fuel-efficient vessel, with all personnel ashore and not exposed to operational risks. This is revolutionary in terms of cost efficiency and enhanced safety, will drastically reduce Reach Subsea’s CO2 footprint and could, Mr Alendal asserts, reduce the cost of providing subsea services by up to 65%.
“Even though the transition from manned to unmanned vessels needs time, it is realistic for us to aim for a fleet of at least 10 USVs by 2025,” said Mr Alendal. He explained that the Reach Remote concept uses a USV in conjunction with a next-generation ROV. The USV or ROV mother vessel will be approximately 25 m overall. With optimised hydrodynamic properties for high-quality data acquisition and subsea positioning performance, the design of the USV is focused on ROV operability and on an extended weather window, compared to conventional ROV operations. The USV has also been optimised for very low energy consumption and a minimal carbon footprint. Using a redundant hybrid electric configuration it will be capable of 30 days or more endurance for most operations, ensuring efficiency and operational flexibility.
With the arrival of Reach Remote and other similar concepts, USVs developed by well known players such as Fugro, Ocean Infinity, XOcean, HydroSurv, SeaRobotics, Kongsberg, AutoNaut and ThayerMahan are being complemented by new, more sophisticated, more capable uncrewed vessels. First-generation USVs, such as those tested by Equinor, were essentially unmanned survey vessels, but new-generation USVs are already being brought to market that can do much more than survey the seabed. In the near-term, these second-generation USVs, such as Reach Remote and vessels recently unveiled by Fugro and Ocean Infinity, will deploy ROVs, autonomous underwater vehicles (AUVs) and above-water unmanned aerial vehicles (UAVs). And in the medium term, next-generation USVs will act as platforms not just for individual ROVs and AUVs, but large numbers of autonomous units that work together.
A glimpse of what may be possible in the longer term is provided by projects being undertaken in the UK. Autonomous survey vessels developed by HydroSurv are being used to reduce the cost of offshore surveys and route inspections and conduct ‘seabed-to-splash-zone’ surveys of offshore structures. Elsewhere, airborne ‘drone swarms’ are being used to reduce operations and maintenance costs in the offshore windfarm environment, while unmanned surface units would be used in conjunction with ‘swarms’ of underwater vehicles designed to take readings on the seabed.
Exeter-based HydroSurv is working closely with the Offshore Renewable Energy Catapult and project partners Reygar and Core Blue as part of an Innovate UK-funded project to develop the USVs mentioned above. The project supported the company’s journey to market by accelerating its technology readiness level (TRL) from TRL 3, experimental proof of concept, to TRL 7, prototype demonstration in an operational environment. HydroSurv’s REAV-16 and REAV-40 autonomous vessels can deploy a range of sensors and task-orientated payloads for survey and inspection projects. As HydroSurv founder David Hull explained, the company’s aim is to “democratise ocean data.” Mr Hull and his colleagues believe that supporting offshore survey and inspection with fully-autonomous survey vessels like RRAEV-16 and EAV-40 could become commonplace.
“This is revolutionary in terms of cost efficiency and enhanced safety”
Of interest to the offshore oil and gas and offshore wind industries is an Innovate UK co-funded research project that HydroSurv is participating in a project known as ‘SeaWynd.’ The aim is to develop an integrated, non-invasive multi-sensor suite for a USV that can collect and collate structural data from offshore structures, from the seabed-to-splash zone. The project uses light detection and ranging and multibeam echosounders to generate ‘point clouds’ above and below the surface. The project partners believe that the data collected using SeaWynd will be superior to that available from other systems, allowing detection and rapid characterisation of abnormal conditions and change detection over time. “Deployment of the SeaWynd suite on multiple USV platforms creates a force-multiplier where multiple tasks can be performed simultaneously,” said the project partners, noting that data from multiple sensors will be combined in a 3D structure that will facilitate inspection and rapidly identify locations requiring maintenance.
In March 2021, it was announced that an industry team, comprising Ocean Infinity, University of Portsmouth, Airborne Robotics and Bentley Telecom, is developing an autonomous offshore wind inspection capability utilising aerial ‘drone swarms’ deployed from an uncrewed vessel. Funded by the Future Flight Challenge programme from UK Research and Innovation and the Industrial Strategy Challenge Fund, the £1.67M (US$2.35M) ‘Drone Swarm for Unmanned Inspection of Wind Turbines’ project will culminate in a system demonstration in 2022.
“Flying Nodes can work on their own, in small ‘pods’, or in swarms of thousands of nodes”
Using 5G and satellite connectivity, the project will see a swarm of drones autonomously inspect wind turbines, removing the need for manual inspection. A 36-m Armada uncrewed vessel from Ocean Infinity will act as the host vessel for the aerial drones, facilitating launch and recovery, recharge, data download and transmission to shore via satellite. As Ocean Infinity business development manager Ramsay Lind explained, not only will this uncrewed solution see a reduced risk to human life, but it will also reduce the environmental impact of windfarm inspections.
University of Portsmouth project lead Dr Sarinova Simandjuntak said that ultimately the aim of the project is to develop a system that can detect and monitor defects or damage to blades and monitor an entire structure in a safe and effective way. “This will benefit offshore windfarms, reducing the time they have to shut down for maintenance and increasing availability and supply,” she explained.
Designed to undertake a wide range of tasks including exploration and production seismic, towed streamer infill, subsea mining and monitoring among others, Autonomous Robotics’ (ARL’s) Flying Nodes can be used to accurately deploy and recover ‘thousands’ of sensors on the seabed in a fraction of the time it would take for sensors deployed from a manned vessel. Flying Nodes can work on their own, in small ‘pods’, or in swarms of thousands of nodes and are designed to operate at depths of up to 3,000 m. The company describes the Flying Node as a hybrid glider/autonomous underwater vehicle that is particularly stable in operation and able to land on the seabed and remain there for up to a year, collecting data before ‘flying’ home.
Describing the application of the Flying Node in the ocean bottom seismic (OBS) market, ARL notes that ocean bottom nodes (OBNs) provide excellent data quality, but at relatively high cost, and that deepwater OBS still relies upon ROV deployment of nodes, which is slow and expensive. It believes it can significantly reduce the cost of OBS without reducing quality by using two ultra-short baseline acoustic positioning systems, one on a node vessel, a second on a USV. The USV is positioned over the nodes as they touchdown to provide good positioning accuracy. Using this approach, a deployment rate of 50 nodes per hour is possible, according to ARL. A similar system has been trialled for pipeline touchdown monitoring.
To date, ARL has completed survey modelling, demonstrating the economic benefits of using Flying
Nodes with unmanned vessels, and requirements and concept of operations for the system have been derived from this modelling. It has also developed feasible concepts for all parts of the system, including accurate navigation of a large number of nodes, deployment and recovery, deck-handling systems and node storage, and built a prototype node to demonstrate the concept. It has also demonstrated autonomous flight of the node during sea trials, with the node landing and taking off from seabed and undertaken a seismic field trial which successfully demonstrated the nodes’ ability to acquire high-quality OBN seismic data.