ROVs ahead of the game

Exploration and production at greater depths and a heightened emphasis on safety could mean even bigger roles for ROVs in offshore operations. Experts say the machines are not just up for the challenge, but ahead of the game. Russell McCulley reports.

The Deepwater Horizon disaster in the US Gulf of Mexico put the spotlight on remotely operated vehicles – their capacity to intervene in blowout preventer operations, as well as routine subsea monitoring and emergency response. The Bureau of Ocean Energy Management, Regulation & Enforcement's new drilling safety rules highlight a number of ROV tasks and requirements, including a directive that all floating rigs must maintain an ROV and trained crew at all times. This should be good news for ROV operators in the Gulf in the future. The present, however, is a struggle in the US, with the moratorium imposed after the Macondo disaster and the subsequent backlog of drilling permit applications delaying a return to normal activity.

‘The climate, in general, is horrible right now because of the blowout and the moratorium,' says Drew Michel, chair of the Marine Technology Society's ROV committee and the organization's president-elect. ‘Things are really down. Everybody's worried and hurting, and not doing much, quite frankly.'

There's been a bit of IRM work that could proceed in the Gulf during the moratorium, which officially ended in October 2010. ‘But not a tremendous amount,' says Michel. ‘If you look at the overall market for work-class ROVs, probably half are on drill rigs. So if drilling is slowed down, or if some of the rigs have left the Gulf to go to other places because of the moratorium, that slows the industry down. Even the ROVs that are still on rigs, if the rigs are idle, the crews are on the beach or have been transferred to other parts of the world.

‘Some of the very best ROV pilots and supervisors that I know, who were on great projects in the Gulf of Mexico, have now gone to other parts of the world because the projects they were on are stopped.'

Deepwater drilling will resume, but under terms that assign more duties to ROVs, says Rory Satterling, general manager of Perry Slingsby's Houston facility. ‘I believe there will be changes in the industry,' mostly in the way subsea operations are conducted in deepwater, he says. ‘And the only way you're going to tackle that is with ROVs. There will be a greater role for ROVs, particularly in the Gulf of Mexico and the regulatory changes that are coming here.'

The changes will likely include ‘more smarts on the seafloor,' Satterling says: more technologically complex BOP control systems and other subsea equipment. ‘I think a lot of the ROV technology was already ahead of what was being put down there,' he says.

Michel agrees: ‘The best thing that can be said about advances in work-class ROVs is that it's almost like a solution waiting for a problem. The technology in underwater robotics in general exceeds the opportunities to put it to work.'

The Macondo aftermath will likely lead to more vigorous testing to ensure that systems are prepared to handle emergencies, says Schilling Robotics CEO and president Tyler Schilling.

‘The interest so far, the most prominent effect, has been that these systems where the ROV is intended to provide override function, people are pretty clear on the fact that you'd better test those things – the ROV and its equipment that you intend to use with the underwater system – to prove to yourself that it will function,' he says. ‘I think in the past, not a lot of that stuff has actually been tested together in a manner that would provide the necessary degree of confidence in the override function.'

Recent customer queries have revolved around the horsepower capacity of ROVs to operate BOPs and other subsea equipment, Schilling says. ‘You actually need to be able to deliver more of the ROV's horsepower through fluid intervention to the blowout preventer.'

Simpler hot stabs
Since its partial merger with FMC Technologies (OE January 2010) Schilling Robotics has stepped up its efforts to implement more automation in ROV functions and to slash the time it takes to conduct service and repair on workclass ROVs. Regarding the former, Schilling says, ‘we're getting pretty far along in the development of a visionguided technique for doing peginhole tasks, most importantly installing and retrieving hot stabs' – a common procedure, he says, but a big challenge for less experienced ROV pilots. To help make the task simpler, Schilling is developing a system that uses a manipulator wristmounted camera capable of recognizing features on a panel, ‘allowing the user to simply tell the system which receptacle they'd like the hot stab inserted into, and our control system is simultaneously flying the ROV and positioning the manipulator to make the hot stab go into the hole,' he says.

In a successful peginhole maneuver, the ROV pilot must align five of the ‘six possible degrees of freedom,' Schilling says: three of the possible rotations – pitch, yaw and roll – and two of the three translations. ‘The challenge is – and what really separates successful operators from the inexperienced – the inexperienced focus on just getting the tip of the hot stab into the receptacle, which requires three degrees of freedom. But then lining up the other two degrees to make the axis of the hot stab and the axis of the receptacle aligned is a lot more difficult. What we're doing is letting the computer do all of that work for them.'

Eventually, he says, subsea equipment could be shipped with ‘fiducials,' or geometric targets that can be recognized by the ROV's camera, that visually transmit information about the equipment, much like a bar code and reader system. Schilling hopes to demonstrate a version of the visualization technology at Houston's Offshore Technology Conference in May and have it commercially available before the end of the year.

‘One of the things we're trying to do is create automation techniques that don't require people to buy extra hardware,' he says. ‘Since the ROVs already have cameras on them, and they already have computers and all the other sensors, what we're trying to work toward are enhancements that just require a software addition.'

Schilling Robotics delivered two HD ROVs in 2010 equipped with what the company calls its integrated hydraulic power unit, a system designed to reduce the time needed to replace an hydraulic power unit in the event of a failure from several hours to less than one hour. ‘All connections that the hydraulic power unit has to the rest of the ROV system are on the same parallel axis,' Schilling says, allowing the unit to be removed and replaced quickly. The same parallel design solution is used on the unit's pumps so a faulty pump can be replaced in about 45 minutes. ‘The goal is to make the effectiveness and the efficiency of the remote intervention crews out there as high as we can get it,' he says.

Effectiveness and efficiency will become even more important as drillers expand ultradeepwater operations. ‘The vast majority of our sales are still the large workclass ROVs, typically 150hp,' says Perry Slingsby's Satterling. Most customers don't fully use the heavy duty ROVs capabilities, he says, but the trend is toward increasing demand on the vehicles.

‘The 3000m [depth rated ROVs] we supplied over the years were typically working in 1500 to 2000m,' he adds. ‘Even though people aren't requesting deeper ones yet, they have been pushing closer to that 3000m envelope. I think we'll see the push to 4000m before too long.'

The increased depth will not be a ‘radical jump' for most ROV components, Satterling believes. ‘The biggest jump will come with the umbilicals, and how you drive the electrical power and data another 1000m deeper.' OE


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