The trend toward deeper, more remote offshore oilfields is driving step-by-step automation of subsea operations while the oil industry awaits its science-fiction dream machine – an unmanned, untethered robot that can tend seafloor wellheads and install equipment without human intervention. Creative approaches were on display at the Subsea Survey IRM 2012 conference in Galveston, Texas, in November, and Bruce Nichols was there for OE.
The lack of breakthroughs in wireless underwater communication and battery capacity is prolonging the wait for a fully autonomous underwater vehicle (AUV), one that will not need a $100,000/day vessel and crew, a heavy tether for power and control or hours to complete a task that might take minutes onshore.
But some relief is coming from workarounds to overcome AUV limitations and incremental improvements in 30-year-old ROV technology.
Hybrid vehicles are in the works that piggyback AUV capability onto proven ROV technology. Subsea docking stations, hard-wired to the surface, are being developed to allow AUVs to recharge and deliver data without resurfacing, reducing launch and recovery time. Software and sensor improvements could boost the speed and precision of work done by existing ROVs while keeping a human operator in the control loop.
Lockheed Martin exhibited its programmable AUV, Marlin, which can fly free while staying on what amounts to a software leash. Last summer, the 10ft-long, tear-drop shaped, 2098lb submarine followed pre-set paths to survey 11 platforms and three other sites in the Gulf of Mexico for Chevron (see panel overleaf). The data gathered was turned into 3D models that the supermajor can use in planning. ‘It was the first commercial, autonomous inspection of subsea infrastructure for an oil and gas major, bringing AUV inspections into a new reality,’ says Lou Dennis, Lockheed Martin business development manager.
Dan McLeod, Lockheed Martin’s Marlin program manager, says the Marlin system represents an advance in autonomous technology, though it still must surface to download its high-res data, recharge and receive new instructions.
‘It actually interacts with sensor data as it’s performing its mission,’ McLeod says. ‘What that allows is adaptive path planning, so it’s optimized to travel around the path that provides the best sensor coverage for the particular mission.’
Autonomous inspection
Massachusetts-based Bluefin Robotics, a Battelle subsidiary, has specialized in defense, environmental sensing, salvage and national security uses of underwater vehicle technology. Now it is offering the technology to the offshore oil industry.
Bluefin subs already autonomously inspect the undersides of ships calling at ports and search for mines in warzone shipping lanes. The capabilities involved are not so different from surveying the legs of an offshore platform or inspecting pipelines.
Bluefin, in September 2011, demonstrated a workaround for limits on submarine battery capacity. It placed a shore-wired docking station on the bottom of Broad Sound in Boston Harbor and used it to recharge and collect data from a battery-powered Bluefin-12 sub after an eight-hour survey mission.
‘We know that AUVs can do certain jobs today. We believe AUVs can do more in the future. The challenge is how do we get there,’ says Omer Poroy, VP of business development for Bluefin, which has delivered more than 80 vehicles.
SAAB’s Seaeye unit is working with Aker Solutions on a seafloor docking station, where an AUV could park and recharge its batteries by induction, as does a battery-powered toothbrush. It will communicate by close-proximity wireless link, possibly optical or radio, while berthed, says Chris Roper, North American sales manager for SAAB Seaeye.
Underwater communication
Woods Hole Oceanographic Institution is working to advance wireless underwater communication, exploring acoustic and optical technologies and is ‘looking for partners who can help bring the technology into use,’ says Andy Bowen, director of the institution’s national deep submergence facility.
Others are working on advanced radio communication. The challenge for all the modes is simple physics: acoustic, optical and radio waves do not yet travel far enough with wide-enough bandwidth underwater to meet offshore oil industry needs.
SAAB’s Sabertooth system is designed to stay submerged for up to a year and be capable of operation in three modes: autonomous, operator-assisted and manual, a flexibility that might ease the transition to AUV technology. The docking station would stay in place for five years, Roper says.
‘Leaving it down there all the time is not a bad idea,’ says Robert Geoghegan, undersea systems manager for Battelle. ‘AUVs are often deployed [and retrieved] daily. If that could become weekly or monthly, there’s a lot less launch and recovery involved.’
Total has been working for six years to develop its Swimmer (Subsea Works Inspection and Maintenance with Minimum Environment ROV) system, an AUV piggybacking its own tethered ROV and operating from more than one docking station, with stations miles apart.
It could stay submerged for three months, roaming from station to station subsea, operating in docked mode or as a free-flyer, sending its tethered ROV out as much as 200m to perform inspections and light tasks such as turning valves.
Herve de Narois, deep offshore manager at Total E&P Research & Technology USA, says he hopes for initial deployment of Swimmer off Angola next year with full commercialization of the system by 2018. ‘Costs are higher and higher for deeper environments, and we have more mature fields, which means you have to have more frequent intervention,’ Narois says.
Hard-wired electric power and fiber optic links are already being installed to serve the Lower Tertiary plays in the Gulf of Mexico. These networks could clear the way to add subsea AUV docking stations to deepwater installations, says Carl Barrett, project manager for 3U Technologies.
‘I don’t think it’s that much of a stretch’ to envision adding subsea communications interfaces to link AUVs to remote operators, he says. Plug-in power stations are also a possibility to provide long duration high-power AUV operations onsite. They are simply ‘add-ons’ to the power and communications networks that are being installed anyway, Barrett says.
Statoil’s drive to develop AUVs stalled with the shelving of the Shtokman project in the Barents Sea, but the company is taking other steps to improve output and reduce the cost of inspection, maintenance and repair, says Kaj-Ove Skartun, section manager for Statoil Subsea IMR. The company is trying to build what amounts to a ‘subsea factory’. That means installing equipment designed for less frequent, more standardized servicing, Skartun says.
The Bluefin-12 entering the unmanned underwater vehicle subsea docking and recharging station (top) which can accommodate up to four AUVs for wireless power and bi-directional data transfer (bottom).Standardized projects
The company has 10 standardized projects underway and 20 more planned as part of the effort to boost average field recovery from 55% to 60% by 2020. Better subsea equipment, more modular parts and tighter planning already have helped Statoil in the past year accomplish twice as many missions as in 2006, with fewer vessels, Skartun says.
A key driver of Statoil’s search for assembly-line efficiency on the surface and on the seabed is the increasing need for high-powered pressure-pumping to support production from mature fields and more difficult strata, he says. That requires greater durability and maintenance capability.
‘It’s changing the game as we know it,’ Skartun says.
There is still plenty of room for improvement in ROVs without moving to AUVs, and more capable software is as good an answer as fancier hardware, believes Peter MacInnes, VP of sales & marketing for Schilling Robotics, a unit of FMC Technologies. With a steadily shrinking supply of qualified operators, automating basic functions such as stability control can make it easier to get trainees up to speed and can eliminate the need for a backup operator, he says. Software strain monitoring also can prevent hardware failure due to operator error, he adds.
Automating light interventions such as turning a valve or carrying out a hot stab – plugging a pressurized hose into a subsea facllity – can improve the speed and precision of repeatable operations by eliminating the imperfect human hand on a joystick, MacInnes says.
All the operator has to do is guide the ROV into place and push a button, he says. Side-by-side videos illustrated his point, showing a real hands-on operator in an oilfield requiring several shaky attempts to complete the same operation that an automated ROV in a test tank finished in one try.
Also on the tethered operations front, SAAB and others envision disposable, thinner, lighter-weight tethers as long as 10km, which would be capable of low-power data transmission. That would allow ROV operations miles from a hub, in ultra-deepwater or under Arctic ice.
‘It has a lot of advantages in hostile areas,’ Roper says.
Aside from technology development, there’s another hurdle for the advanced AUVs of the future. Because offshore operations are expensive and risky, oil companies and their regulatory agencies require confidence that an AUV will do what it is supposed to do, where it is supposed to do it, in absolute safety.
Operator demand
To smooth the way, DeepStar, a consortium of industry players including major oil companies and service operators, is studying opportunities to standardize equipment and address regulations to accommodate AUV operation, says DeepStar director Greg Kusinski. A lot depends on operator demand for new technology, which interface standardization and regulatory acceptance could facilitate, he says.
‘At the end of the day, it will be up to the operators to deploy them.’
Operator demand has been slow to emerge as steadily improving ROVs keep meeting offshore needs. One indicator: subsea robotics company Oceaneering, which has more than 280 work-class ROVs in service, has been involved in AUV development but has not brought it to the oil industry yet.
‘There’s a lot of money at stake so decisions tend to err on the side of caution when it comes to adopting new methodologies,’ Poroy says.
But as subsea oilfield development grows in complexity, AUVs are likely to develop faster than the 30 years it has taken ROVs to become everyday tools. The right circumstance – perhaps a big, difficult project like Shtokman – could present a business case for AUV use, Statoil’s Skartun suggests.
‘Once you have a business case, you can start funding it, developing it,’ says Jim Jamieson, remote systems manager for engineering, construction and ROV-equipped services contractor Subsea 7. OE
Subscribe
