Resident ROVs 1: IKM

This was in the latest edition of UT3 . I will be posting the entire magazine it on here shortly. If you wish to receive UT3, just send an email to [email protected] with the world YES in the s

Early this year, a warning rang out across the Tannoy on Statoil’s (now Equinor) Snorre B platform in the North Sea, cautioning personnel not to venture outside as there were 20m waves breaking against the side of the semisubmersible platform. At the time, IKM was carrying out sea trials of its new ROV system. 

At any other time, these adverse conditions would have hampered the operations and they might have been cancelled because of the potential challenges in retrieving the vehicle to the surface. 

In this instance, however, the ROV was safely sitting in its garage on the sea floor unaffected by the weather 300m above. Meanwhile, the ROV pilots were in the relative comfort of the shore control room south of Stavanger. 

Ironically, rather than being a problem, this displayed the intrinsic advantages of having a residential ROV.

“A Residential ROV ( R-ROV) can be described as a permanently subsea-installed underwater vehicle that would usually be garaged on the seabed rather than be deployed from a dedicated support vessel, or take up valuable platform space," said operations director at IKM, Jan Vegard Hestnes. It can confer considerable operational cost savings, particularly compared with typical existing ROV projects."

The R-ROV should be thought of a precision tool and best suited to specific tasks rather than routine work. If the work consistently requires significant amounts of heavy tooling being put on the vehicle every day, for example, then a resident ROV isn’t the right vehicle and a standard work class ROV may be a better solution. For observation and light workclass duties, however, it confers a number of advantages, particularly economic, as well as offers a higher rate of availability. 

“We first came up with the idea for a resident ROV many years ago, and in fact, we approached Statoil with the concept. After presenting our ideas, they responded by adding their own ideas and potential requirements. 

This soon developed into an in-depth mutually instructive dialogue and a couple of years later, in the summer of 2016, they awarded us a breakthrough NOK0.75 billion ten-year contract for ROV and subsea services for Statoil's Visund and Snorre B assets," said Hestnes.

This contract would encompass four ROVs, one of which was to be the new residential design. IKM immediately enlarged the concept study, basing the resident design on its Merlin UCV (ultra compact vehicle) electric workclass ROV .

“If you looked at the Merlin UCV and the residential version together, an untrained eye would have difficulty differentiating the two. We have made modifications to the manipulators and with the cabling connectors, but the two vehicles look virtually identical. 

"The Merlin UCV has been in operation for many years, its systems are field proven and we needed to call upon that reliability. One of the challenges that we did find potentially difficult to meet when first considering the design, however, was from where to control it."

Obviating the use of an support vessel reluctantly meant that IKM's only alternative was to install the control station on the platform itself, where space was limited. This part-fuelled the drive to establish an entirely new concept of remotely controlling the vehicle from shore. In 2017, the game-changing development work culminated in what IKM believe was the world’s first commercial onshore controlled ROV operations of its type. 

The project will see to three Work class ROVs and an Observation ROV on Statoil’s Snorre B and Visund installations being controlled from IKM Subsea’s onshore control center from the dual control room at Bryne, Stavanger. The staffing of the operations will be performed by a combination of both onshore and offshore personnel 24 hours a day throughout the year.

“The R-ROV has now been in operation since mid-January. In its first operation, it was submerged for 50 days. Since then, it has been used most days,"said Hestnes.

“Like all ROVs, it requires a power source and a two-way data link for control and imaging. In this case, platform power and communications signals from the Snorre B semi-submersible are run down by an umbilical cable to the subsea garage, and via the tether management system, to the vehicle. 

"The platform communicates with the onshore at Bryne via Internet or fibre lines and a radio link from one of the platforms to the other. Quite a few platforms in Norway have fibre lines. Failing that, it can be operated by 4G mobile broadband."

The R-ROV uses an astounding 1000m tether, giving a 2000m working diameter. This is because Equinor wished to reach their furthest wells. Remarkably, even having to carry power to the vehicle, the tether is not a particularly large diameter. It is neutrally buoyant in water so that it can be pulled long distances.

 “Because the R-ROV is of an electric workclass design, it is able to carry out wide a range of operations with using manipulators and subsea tooling. It has already been used for valve operations, inspection, cutting operations and opening hatches. It is possible to lower tools into the stand near the garage, and the ROV can use them immediately.

“Because the R-ROV will not be recovered for months, we have to make sure we monitor all parameters closely and detect issues before they become problems. 

With sensors located at strategic points , we can monitor functions throughout the vehicle such as temperature pressure and oil quality. We even have the capacity that if we see that we are starting to get dirt or water particles in the oil, we can remotely flush the oil out and refill subsea," said Hestnes.

As operational data is collected and analysed, IKM plan to see how to maximise its operational use.

“We have a target of keeping the vehicle resident for 90 days at first, extending this time with experience. As part of the next wave of developments, we also plan to incorporate a skid. 

 We already have made room in the garage for a skid and envisage a system in which the ROV can select from one or more skids depending upon the work," said Hestnes.