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Living in a subsea world

Written by  Elaine Maslin Friday, 01 September 2017 00:00

Oceaneering and Sonsub are making moves towards subsea resident remote operated vehicles. Elaine Maslin reports on their progress.

The eNovus ROV illustrated. Image from Oceaneering.

The move towards increased subsea processing on the seafloor is seen as a driver for producing resident subsea robots.

While many people have been focused on developing a subsea resident vehicle, which would reduce the need for support vessels, Saipem’s Sonsub business has been developing a strategy based on a fleet, which it calls the Hydrone platform, to perform life of field subsea services.

Hydrone R, a resident vehicle, is the core of the fleet. But, alongside Hydrone R are other vehicles, both resident and semi-resident, as well as a work class remote operated vehicle (ROV), to be operated by a multipurpose support vessel (MCV). The firm’s Innovator 2.0 work class ROV is already in operation. A version of the Hydrone R, which Sonsub wants to be able to operate in tethered, untethered and autonomous underwater vehicle (AUV) mode, is expected to begin tests next year.

“In the future, we will see a completely different way of providing services at sea; active local heating, Springs (see page 30), Spoolsep, Multipipe, heated pipe-in-pipe,” says Francesco Cavallini, commercial and tendering manager, Sonsub, mentioning some subsea processing technologies Saipem is developing. “Life of field subsea [services] will be critical to make such projects sustainable.” But these activities are currently reliant on the use of an MSV, he says. With resident vehicles, there is an opportunity to be more proactive, or even predictive, and perform immediate interventions in the event of need.

E-ROV piloted from an onshore control room. Image from Oceaneering. 

The Hydrone fleet

The Hydrone fleet comprises the fully resident Hydrone R, Hydrone W (a work class semi-resident ROV) and Hydrone S (an advanced survey and inspection unit). They can be supported, when required, by Saipem’s new heavy duty work class ROV, Innovator 2.0, based off a support vessel with a crane. Hydrone R and Hydrone S would be docked subsea with a common subsea garage, which would also house various tooling skids, as well as recharging facilities.

Sonsub’s objective is to have Hydrone R in the water next year and fully operating for demonstration. The Hydrone R is described as a modular subsea resident and reconfigurable intervention ROV, integrated within the field. It would be able to move between different garages, according to mission requirements. It would also be open to third-party component integration, says Giovanni Massari, a Saipem project manager.

The unit would be controlled from a floating production vessel or from shore in tethered or untethered mode, or in AUV (also untethered) mode, when travelling between different stations, or performing a pipeline inspection. It would be available for use in emergencies, to “see” what is happening and intervene, if necessary. It would also have a “menu” of automated missions, which could be selected remotely by operators onshore and implemented autonomously by the Hydrone-R.

Massari believes that there will be an evolution in this technology, but that the resident ROV will be able to perform normal ROV duties. A number of technologies will need qualifying, he says, including long endurance capability, artificial intelligence, subsea batteries and recharging, as well as remote manipulation, subsea Wi-Fi, specific investigation and intervention tools.

For these technologies to take hold, Massari says that there is a need to promote a standard for resident subsea robot interfaces (between the base and subsea production systems and between base and vehicle). The API RP17H revision will include some recommendations for AUV/ROV interfaces on subsea production systems. “Standardization is a must,” he says.

For Massari, greenfields should also be designed to accommodate these technologies, in order to maximize their potential. “The number of functions they could perform could be increased through proper design of greenfield systems,” he says.

Remote reality

Hydrone-R conducting a pipeline survey in AUV mode. Image from Sonsub.

Statoil and Oceaneering have taken the resident remotely operated vehicle (ROV) concept a step further.

Under a contract with Statoil, Oceaneering deployed a “cage”-based ROV on the Troll field, in the Norwegian North Sea, using control from shore via a 4G LTE offshore broadband network.

The cage was fitted with battery packs, to power the ROV, and connected to a data buoy, which enabled communication to an onshore control center in Stavanger. The deployment, under Statoil’s E-ROV project, is the latest in a series of steps Oceaneering has taken in remote piloting.

The company first remotely piloted a Nexxus work class ROV, operated off the MSV Olympic Intervention IV, in the Gulf of Mexico, via a satellite link, in 2015. Satellite links have medium bandwidth and medium latency, which add lag to communication rates, according to a presentation by Arve Iversen, ROV Operations Manager, Oceaneering, at UTC Bergen. LTE, however, a 4G version of which is used on the Norwegian Continental Shelf, has medium bandwidth, but low latency, reducing lag.

Last year, Oceaneering again tested remote piloting from the Songa Endurance semisubmersible drilling rig using a Magnum 183 work class ROV and the Telenor 4G LTE broadband network. The ROV performed a number of tasks from the semisub on the Troll field, offshore Norway, with onshore control in Stavanger, in December 2016. Tasks included stabbing an HP-cap high-pressure seal test line with a dummy stab, laying down and raising a riser connector support frame, and cleaning a section of template hatch structure.

Data were transmitted in 58ms, and video in 200-400ms. Bandwidth was 0.2 Mbits/s for data and 2 x 2 Mbits/s for video. This will improve as networks improve and even as 5G networks are introduced, Iversen says. In 2020, 5G is coming. Then, the latency will be reduced by 90% again, and it will be “really, really good,” said Pål Atle Solheimsnes, leading advisor for subsea intervention and diving at Statoil, at Subsea Valley in Olso, Norway, in April. “We can use it on all subsea production systems in the North Sea.” (OE: June 2017)

However, Statoil wanted to go further for its E-ROV concept. This is a fully standalone and battery-powered work class ROV system remotely piloted from onshore via surface 4G LTE data and a communication buoy.

Oceaneering was awarded a contract in January 2017, using its eNovus electric work class ROV, stationed in a subsea garage (cage, tether management system, and battery packs), using battery power to operate, and with onshore communication and control via the 4G LTE data buoy. It was deployed using a Statoil-operated inspection, maintenance and repair (IMR) vessel at the Troll field.

The battery packs were 120-kWh capacity with 100kWh on the cage and 20kWh on the vehicle.

Iversen says that the vehicle would be able to sit in standby “sleep mode” mode for more than six months, or standby “awake mode,” with systems off, for 10 days. It would be able to perform stationary observation work for four days, slow-moving inspection work for 40 hours, travel at 1knot for 24 hours, or do left and right manipulator work for 17 hours. Solheimsnes says that the battery pack could be scalable and updated as battery technology improves.

Techniques helping to improve remote operations include advanced adaptive video compression, automated ROV control (such as hands-free piloting and advanced station keeping), and automated manipulator control, using the likes of 3D visual object recognition and automated hot-stabbing, Iversen says.

Options for use of this technology include remote support from other offshore locations, multi-vessel operations, and the resident ROV.

There are a couple of deployment concepts for the E-ROV, one involving the Seven Viking IMR vessel, with several E-ROV skids on board, almost doing a “milk round,” deploying the skids via its moon pool to the seabed. Another has the Normand Ocean deploying one skid, going off to do other jobs, and returning to collect the E-ROV when it has completed its work.

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