The Magazine for Underwater Professionals
The design and development of a revolutionary autonomous subsea inspection capability
In 2020, the topic of autonomy needs no introduction. Many corners of the global maritime industry are looking into the capabilities of autonomy and exploring the operational possibilities it could bring. The offshore energy industry is no exception.
Inspection of subsea assets is a routine task for offshore oil and gas and wind operators. As many oil and gas platforms in and around the UK are coming towards the end of their life, monitoring and maintenance is therefore an increasingly important task; one which must have minimal impact on routine business.
The ability to increase efficiency and reduce risk to human life has brought autonomy to the forefront as a technology area of interest.
The Autonomous Robotic Intervention System For Extreme Maritime Environments (ARISE) project was kick started in 2017 to address this idea. Led by L3Harris (formerly ASV Global, UK), and partnered by the University of Exeter, UK, the project sought to develop an integrated autonomous system to de-risk and enhance inspection work in the offshore environment. The project was fortunate to receive part-funding by the UK government’s innovation fund, Innovate UK.
In its early days as ASV, L3Harris’ autonomous vessel business developed the industry’s first autonomous surface vehicle (ASV) system for offshore oil and gas tasks. The C-Worker 6 ASV was developed with input from oil and gas company Technip, France, and was designed with a modular moon pool payload space to make it suitable for housing a variety of sensor suites for different tasks. The ASV successfully demonstrated its ability to withstand harsh offshore conditions carrying out tasks such as acoustic positioning and data harvesting.
Following a series of proof of concept operations and a wealth of industry feedback it was concluded that the real key to unlocking the potential of ASVs for offshore energy tasks was increasing the payload capacity to give the potential to house an inspection-class ROV. This would need a larger moon pool and therefore a larger boat. Introducing the C-Worker 7.
The C-Worker 7 was launched for the first time in 2016. Measuring at one metre longer than the C-Worker 6, the seven-metre ASV was furnished with a 2.5-metre by one-metre by 1.5-metre moon pool, one extra metre than that of the C-Worker 6.
Following the design, build and commissioning of the new ASV – the next stage would be to develop and prove its capability as an effective tool in offshore oil and gas. The first major job for the C-Worker 7 was for Subsea 7, Luxembourg, in the West Nile Delta field, offshore Egypt, carrying out touch down monitoring using multibeam echosounder systems.
The next step in the road to commercialisation was to expand the ASV’s capability to operate an ROV. This became a reality when Innovate UK offered part-funding to get the project off the ground. In November 2017, the ARISE project was born.
Phase 1 of the project ran from 2017-2018 and entailed the design work and feasibility testing of deploying and recovering an ROV from the C-Worker 7.
The design work and initial testing took place from L3Harris’ site in Portchester, Hampshire, UK, and early tests were carried out in the Solent.
The whole payload system was hosted within the moon pool of the C-Worker 7, requiring only power and data connections from the host vessel. The system included:
The development and early testing phase culminated in a two-week demonstration in Cawsand Bay, Plymouth, UK. The demonstration, which was supported by oil and gas supermajor BP, UK, marked an industry first showcase of an ASV deploying, operating and recovering an inspection-class ROV.
In proving its capability to conduct vertical and horizontal subsea inspection, the system showed itself to be an ideal solution for tasks such as jacket and hull inspections as well as pipeline and cable survey.
During the demo it was said by BP that the system could enable the organisation to take people out of hazardous environments – a continual point of consideration for the company. “The C-Worker 7 autonomous vessel, paired with an ROV, has a very significant potential to change the way subsea inspection tasks are carried out. It is an exciting time for the oil and gas industry. The technology is there – imagination is the only thing that can hold the industry back,” remarked Peter Collinson, senior subsea and environmental specialist, BP.
As well as the successful showcase and strong endorsement from industry, there were some important lessons learnt during this first phase of the project. It was acknowledged that to be effective in real world operations, the ROV’s tether would need to be much longer. The 50-metre tether was sufficient in proving the concept of operations in Cawsand Bay but in offshore environments, deeper waters would require a much longer tether. A longer tether would allow the C-Worker 7 to keep a greater distance from the structures being inspected, therefore making for a much safer operation with lower risk.
Whilst proven effective in relatively calm sea states in the Bay, the LAR system for the ROV would perhaps not prove so effective in more challenging offshore sea states. The current system relies upon the ROV being flown into the moon pool and, given its small parameters, requires a lot of precision from the operator. A significant swell would make this much more difficult.
The setup of the system in its concept phase relied rather a lot on human input as parts of the system were operated in a remote control mode as opposed to fully autonomous. Whilst L3Harris is known as a master of surface autonomy, underwater autonomy is different and as such this first phase was approached with an extra level of cautiousness.
The precautionary level of remote supervision consumed a higher than desirable 10Mbps of bandwidth. This was due to multiple remote desktop sessions and camera feedback. As the level of autonomy for the underwater piece continues to evolve it will naturally alleviate the matter of the system using too much bandwidth. The more autonomous a system is, the less feedback will be required so whilst it wasn’t quite a lessons learnt, more a point to note, the level of autonomy and trust in the system must increase before this system is workable offshore.
Following the success of the initial proof of concept operations and demonstrations, the project continued into a second phase which began in spring 2019 and is set to run until spring 2021.
Phase 2 kicked off with daily demonstrations at Ocean Business 2019 in Southampton, UK, of the phase 1 prototype system, packing out the quayside demonstration area.
Taking all of the lessons learnt and feedback from phase 1, the second phase seeks to evolve the system to a pre-commercial state capable of completing inspection down to 150 metres water depth. BP also formalised its role as project partner, demonstrating its commitment to bringing autonomy into the oil and gas mainstream.
In order to achieve greater depths, the ROV’s tether will be increased to 200 metres. Different concepts of launching and recovering the ROV will be explored in order to remove the onus from the operator and rely more on the system. Early work has begun to look into the possibility of catching the ROV underneath the hull, negating the need for it to be flown.
L3Harris continues to develop its autonomy capability across the board, so this project will be able to capitalise on features such as improved over the horizon autonomy and autonomous navigation capability. The company’s machine learning capability will reduce bandwidth usage, with the operator only being given information deemed necessary by the system.
This phase will see mechanical and electrical improvements fuse with the company’s autonomy developments to result in a system that will be able to operate in the field in a pre-commercial test. Operationally these trials will demonstrate the commercial uses of the integrated system, providing multiple timely, high quality, datasets at low cost, compared to current ship-based survey systems.
Once deployed this will be a game changing system enabling significant reductions in terms of cost and time spent at sea for both operators and ships. The ultimate outcome will be a system that negates the need to put people at risk in the extreme environments of offshore renewable energy and oil and gas. The system will be deployed in commercial North Sea inspection operations in summer 2020.