Multi-tasking

Collaboration on- and offshore the Netherlands has resulted in a new concept in platform operations and maintenance. Elaine Maslin reports.

Wagenborg’s Kroonborg. Photo from Wagenborg.

Across the North Sea, platform maintenance is a costly and logistically complex exercise, involving supply ships, helicopters, crew changes, all often overlapping one another across multiple disparately owned assets.

In the southern North Sea, where many assets are now unmanned, operators Shell UK and Nederlandse Aardolie Maatschappij (NAM), working together as ONE Gas, operating some nine manned and 47 unmanned installations, decided to take a different approach by sharing logistics and transport.

With the help of Dutch contractors and engineers, they have created a new concept in offshore facility operation and maintenance in order to realize their new approach – it’s called the Kroonborg, a walk-to-work offshore maintenance vessel.

The vessel, which started work offshore in April this year, is a completely new type of vessel, designed in corporation with Dutch shipyard Royal Niestern Sander, with the help of Groningen-based Conoship International and Dutch logistics firm Royal Wagenborg, which will operate the vessel on a 10-year contract.

It is a workspace, floating hotel and a means of transport to and from offshore platforms, rolled into one, a little like a Swiss army knife. Working on two weeks on, two weeks off rotation, the vessel, which enables crews to “walk to work,” via a motion compensated gangway, will be used for everything from basic maintenance to isolation and live well restarts on unmanned installations.

“That approach of operating and maintaining the offshore installations is pretty new and not very common worldwide and that requires this new vessel,” says Johan Adriaanse, director operations, Wagenborg Offshore. Gert Vanderheyden, client representative, NAM: “It is not just a replacement vessel of one or the other vessel, it is a brand new game.”

According to Wagenborg, Kroonborg’s use will reduce helicopter flights by up to 600 flights a year and, being the first GTL-fuelled offshore vessel, it also has green credentials.

The dynamically positioned, DP2 vessel, is 79m-long, 16m-wide with a 5.4m draft, with a service speed of 12.5 knots and 10,000hp. It has transportation, accommodation, workshop and storage for 60 people, including 40 maintenance and service personnel, who will work in two shifts, walking to work on facilities using an Ampelmann offshore access system.

At its heart is a package of start-up and intervention equipment that will enable wells to be restarted quickly and efficiently. Carrying the chemicals required for startups meant new below deck chemical tanks had to be designed for the vessel.

The unit also has a motion compensated Barge Master T40 crane, to transfer equipment and supplies onto platforms, in wave height up to 3m, thanks to Dutch firm Barge Master’s motion-compensation technology.

“Ensuring that the hook is stable in all directions really is new,” says Theo Klimp, Fleet Director of Royal Wagenborg. The crane will be able to lift up to 5-tonne at 20m outreach and up to 30m high. Kroonborg comes with a fast rescue craft and a daughter craft, one which can stay on one location, so the Kroonborg can go to other location to deploy workers. It also has a FROG escape training unit for emergencies.

Perhaps the most impressive aspect of the new vessel is the time it took to design and build it. The cooperation agreement between NAM, Shell and Wagonborg was signed late 2013. To get the vessel built ready for launch early 2015, Royal Niestern started building the hull before the engineering was complete, so that engineering and construction were running in parallel. A key enabler in this type of approach was collaboration and use of a digital 3D model, which all the firms involved were are able to work on and in.

Now the vessel is out and operating, it is proving its worth. Tony Kett, marine operations manager, Shell UK: “I don’t think we realize just how significant this is. You will see, I believe, we will be starting a trend here in completely changing the way we are operating and maintaining our platforms.”