Subsea challenges are in focus at this week’s Underwater Technology Conference in Bergen. While the conference examines future oilfield challenges, we take a look back at past innovations in the industry. In the second of a three-part series, Elaine Maslin looks at the evolution of the ROV.
If you had to track the technological evolution of the oil and gas industry, tracking the evolution of the humble ROV (remotely operated vehicle) would be a good start.
Today, there are more than 1100 work-class ROVs in operation. They now come with the latest navigation software and designs are being introduced with combine machine and human interface to help automate control and wireless communications technology.
But, the prevalence and future capabilities of ROVs was not always obvious to the industry. Operators were, from the start, concerned with how they would carry out operations on their new subsea wells and facilities, when they reached 150m plus, the limit of safe diving depths, reveal papers from the Underwater Technology Conference archives, which have been made available from 1982 thru 1996.
ROVs were already being used, but were not yet prevalent, and vying with alternatives such as manned submersibles, dry chambers, and atmospheric pressure diving suits. “Working within design conditions, ROVs perform excellently,” Svein Mathiassen, then director of Seanor VBB, at the 1982 UTC. But, beyond their design conditions, they were “unable to adapt,” unreliable and “added complexity.” Early manipulators lacked versatility and launch and recovery systems (LARS) required refinement.
According to Per J Thingstad, then of Norwegian firm Myrens Verksted: “An ROV is only as useful as the tools it carries, i.e. the number and kinds of tasks it can perform. In the simplest case it may just carry a camera.” However, the optimism that these units would be able to do more was there. “More advanced vehicles may perform physical measurements or even do actual work,” he added.
By 1986, the focus soon turned to more effective tooling and ROVs were starting to influence subsea equipment design. A 1986 presentation by Comex Houlder Diving and Vetco Gray in 1986 highlighted a failure to engineer the interface between the subsea system components and the ROV.
In 1988, ROVs made the big time – the cover of the UTC program. In fact, the 1988 UTC was combined with “Intervention 88,” organized jointly by UTC and the Undersea Vehicles/ROV committee of the Marine Technology Society of the USA. “In recent years, vast improvements have been made in reliability of ROV systems, such that they are now making real in-roads in fields which have traditionally been the territory of the diver,” said presenters from Sub Sea Dolphin that year. “Most subsea inspection tasks are now carried out by ROV and an increasing amount of maintenance and construction tasks are being worked on.”
Technology development, driven by new field developments, a period of needing to reduce costs in the 1980s and restrictions on diving depths all conjoined to make ROVs widely accepted, they said, with subsea systems now being designed specifically for ROV intervention. But, they added, there was more to do – ROVs had yet to embrace new “high technology products”, such as lasers, microprocessors and advanced optical products, they said. Manned submersibles were still on the scene and divers still the mainstay of underwater maintenance.
But, the ROV industry was maturing. The need for common standards for docking systems, standard valve stems, local command panels, ROV operable hydraulic shackles, etc., were arising. Throughout the 1990s, additional ROV capabilities and other operational challenges, such as launch and recovery operations, were also being addressed.
By the mid-late 1990s, the next challenge was looming – 400-1000m deep operations had been achieved; 2000m depths were now on the radar and a step-change in design was needed, Oceaneering’s staff engineer Larry Mackey told the 1996 UTC. To handle the greater pressures, wall thickness would need to increase, which would mean greater flotation requirements. A greater understanding of fatigue cycles would be required, as well as better management of connector penetrations, more focus on umbilical cables and tension capacity requirements, and new tether management systems. ROVs, in short, were growing up yet again and increasing in size and power.
The next generation of vehicle was also now being considered, with help from the defense sector – untethered, acoustically controlled underwater vehicles for deepwater seabed mapping.
For now, that is where the UTC archives stop. But the story of the ROV continues. ROVs are now entering a new phase, one where ROVs were not designed just for their function, but also for ease of use, just like iPhones and smart cars, using the latest computing technologies.
At UTC 2013, Total presented a life of field AUV for autonomous underwater pipeline inspection using an on-board stored world view and visual recognition technologies and wireless subsea communication technologies. The next Holy Grail is life of field AUVs that are also able to perform actual work – as had been the hope for ROVs in 1982. The evolution continues.
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