Greater exploration: deep-sea journeys

15 July 2015

Submersible vehicles have been exploring the ocean since the 1980s, and with energy companies venturing into increasingly inhospitable environments, the need for them to evolve becomes greater. Chris Godfrey speaks with Subsea UK’s Neil Gordon to find out how technological advancements have enhanced the abilities of unmanned vessels and what we can expect to see from the next generation.

The US science community was reminded of the challenges associated with deep-sea exploration in May last year, when a hybrid remotely operated vehicle (ROV), Nereus, went missing in the Kermadec Trench, just north-east of New Zealand. With only surface debris recovered, it's assumed the flagship explorer imploded - a result of the intense pressure experienced 10km below the surface. Despite being equipped with some of the latest technology, it succumbed to the perils of the ocean - and at $8 million a vehicle, that's an expensive lesson to learn.

While the price of failure is no doubt dear, inaction could be potentially more costly for energy companies. As oil prices continue to fall, and with skilled labour in the sector becoming a rare commodity, firms are under increasing pressure to find new ways to drive down production costs. ROVs and autonomous underwater vehicles (AUVs) have presented firms with the perfect opportunity to do so. For many, they're worth the risk.

Commercial ROVs and AUVs were originally conceived to overcome the limitations of human subsea divers. Since the 1980s, they've become a critical component in the operations of energy companies, performing a range of inspection tasks at great depths. However, as exploration continues to lead firms into even deeper waters and more inhospitable environments, vessels need to continue evolving to overcome their own limitations.

Inspector gadgets

The growing demand for greater capability has fuelled a technological evolution and given rise to autonomous intervention vehicles (AIVs). While surveys and inspections are now common practice for underwater vessels, this growing class of vehicles has the potential to engage in intervention activities, such as construction support and repair, with near-total autonomy. For the time being, though, the majority of autonomous underwater vehicles are confined to inspection activities.

"Current requirements placed upon ROVs and AUVs are becoming increasingly demanding, meaning that vehicle and operator abilities are pushed to the limit," says Neil Gordon, chief executive of Subsea UK, the industry body and focal point for the British subsea industry. "But advances in technology are keeping pace with the needs of the industry, and helping to make operations, particularly in subsea inspection, more efficient and consistent, as well as less costly."

The subsea industry now generates more than £9 billion a year, supporting around 50,000 jobs, and as energy companies seek ways to overcome the pressures of declining oil prices, the cost benefits of underwater vehicles will likely perpetuate the sector's expansion.

"Offshore assets, such as drilling rigs and subsea construction vessels, can command high rates, ranging from $80,000-500,000 a day," says Moray Melhuish, commercial director with ROVOP, an independent provider of remotely operated subsea vehicle services. "If an ROV isn't operational, costs can quickly escalate as they're always on the critical path of any subsea project. Therefore, crew competence, reliability and ease of maintenance of these systems are crucial, and technological advancements - onshore and offshore - have contributed to the effectiveness and efficiency of ROV operations."

Recent technological advancements to ROVs and AUVs have enabled dramatic cost reductions through boosts to their efficiency.

Improvements to launch and recovery systems have significantly negated the impact the environment and weather conditions have on operations, and increased the operating window, with year-round deployment now possible. Vessels have also benefitted from improved ergonomic design.

"Typically, AUVs have been torpedo-shaped and are really only stable when moving in a forward motion," says Gordon. "The new shape, extra thrusters and, in some cases, addition of dynamic positioning capabilities make them more stable and manoeuvrable, allowing them to be more three-dimensional in carrying out tasks.

"They're also able to gather much more accurate data. Without the up-and-down movement of a vessel, the quality of the data gathered is significantly enhanced, bestowing these vehicles with the ability to operate 365 days a year, in all environmental and weather conditions."

As well as improvements to manoeuvrability, the inclusion of advanced mathematical and technological applications has significantly enhanced the navigational ability of newer models. This improved system allows vehicles to be deployed from rigs, floating platforms and even beaches, eliminating the need for surface vessels and further reducing operational overheads.

This greater on-board intelligence stands to improve more than just vehicle positioning.

"Through highly sophisticated, clever software and image recognition, AUVs and ROVs are able to automate standard survey and inspection tasks," says Gordon. "This software enables such vehicles to reason logically when faced with a fault in a pipeline, for example, and then return to the surface with accurate data to allow the correct operation to be undertaken to fix it."

"While surveys and inspections are now common practice for underwater vessels, this growing class of vehicles has the potential to engage in intervention activities with near-total autonomy." 

ALIVE and kicking

Despite recent technological developments, AUVs and ROVs are beginning to show their age - and with that, their limitations. Current models are only able to carry out inspection and survey operations, but in the near future, deployment of a wave of next-generation AIVs able to carry out light remedial intervention work is expected.

"Subsea 7 is one of the pioneers of these vehicles, which are already coming to the market," says Gordon. "Advances in technology will eventually see support vessels eliminated and AIVs launched directly from the production facility. It may even be possible to for an AIV to be 'parked' on the seabed, able to recharge itself and transmit data from there."

Though such a feat is one for the future, Cybernetix has taken a huge step towards total automation with its EU-funded Autonomous Light Intervention Vehicle (ALIVE) project. ALIVE aims to create a device able to freely navigate and dock underwater under the supervision, rather than control, of operators, and upon completion, it will have station-keeping, auto-docking and manipulation capability.

So far, preliminary trials of the device have proved successful, with it faring well in rough seas, and undertaking pre-programmed operations such as using its hydraulic arm to open and close valves.

Automatic for the people

Although technological developments may have made greater operational capability possible, the vehicles are still only as efficient as their operators. Without the necessary skilled personnel using them, the advantages they afford are irrelevant. Putting measures in place to ensure an adequate pool of skilled labour exists has become as important to the sector's growth as engineering the ROVs and AUVs themselves.

"Remote intervention technology continues to evolve at a fast pace, which we believe will allow ROVs to carry out more autonomous tasks, reducing reliance on human pilots," says ROVOP's Melhuish.

"That said, pilots continue to be required for control, maintenance and repair, and it is therefore important to focus not only on the technology of ROVs, but also on the competence, training and continued development of those operating them. To ensure that subsea projects are executed as efficiently as possible, competent personnel must be provided with the best possible equipment."

ROV training simulators have become so sophisticated and realistic that a full project mission can now be programmed, giving a computer-generated replica environment of the entire seabed and subsea structure. Incorporating sea conditions is also possible, allowing poor visibility as a result of microorganisms, or the variable strengths and directions of mid-water currents to be considered. It's a similar model to that used in flight simulator training or Formula 1 track testing, and allows realistic 'dress rehearsals' to be undertaken, ensuring safe and efficient execution of the project.

Though the technology still requires some development, it may not be too long before the seabed plays host to a range of AIVs carrying out everything from the maintenance of underwater facilities to assistance in rescue operations and collection of hazardous materials. The more advanced they become, the more they highlight the limitations of older ROV and AUV models; in time, their cost-effectiveness and ease of use could see them replaced by AIVs entirely.

It will take years of human research and development before this happens though. They may not be able to explore the depths of the ocean themselves, but for now at least, humans do still hold some value below the surface.

Increasingly inhospitable environments of the deep sea...

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