Rapid mobilization

Speed is of the essence on some projects and that’s just what SAL Offshore faced offshore Alaska. Elaine Maslin reports.

MV Svenja installing the monopod. Photos from SAL Offshore.

SAL Offshore had to mobilize, including adding significant deck equipment and accommodation packages to one of its vessels, in just 10 weeks for a project to install a platform over a gas conductor well in a remote, challenging part of the Cook Inlet using a single vessel.

The Kitchen Lights Unit (KLU), operated by Luxembourg headquartered Deutsche Oel & Gas, sits in the Cook Inlet, home to just 16 production platforms, as well as strong tidal currents and range, dating back to 1964.

Furie, bought by a company owned by Deutsche Oel & Gas, discovered the deposit in 2011 and decided on a 1200-tonne monopod platform with 700-tonne topsides development concept in 30m water depth. The platform was built in Texas and transported by barge to the Cook Inlet where contractor Florida-based Crowley Maritime contracted SAL Offshore, based in Delft, Netherlands, to carry out installation.

SAL Offshore opted to use the Svenja, a Type 183 vessel built in 2010, with two, 2000-tonne combined capacity portside cranes. But, not before the 20-knot capable heavy lift vessel, was upgraded.

Working with Crowley, the Svenja had to be prepared in a shipyard in Singapore to add temporary living quarters for 60 supporting team members, plus 10 additional mooring winches, as an adjustable mooring system, and a 3D sonar system had to be installed.

MV Svenja installing the topsides.

Once on site, the team had to drive a king pile into the seabed using an 80-tonne Menck hydro hammer, then lift and “threading” the monopile exactly over the wellhead, using the king pile as a guidance to slide along into the depth. The work was done using purely sonar imaging, due to zero underwater visibility. Finally, after placing and grouting eight piles, the module support frame was installed, followed by the topsides and helideck. These procedures also had extremely tight tolerances, to meet crane outreach limitations and without touching any of the mooring lines.

What’s fairly unique about this project is that the Svenja, equipped with a Kongsberg DP1 system, was the only construction vessel in the field for the work. It was also working in strong tidal currents, at 5-6 knots, and tight, four-hour, high tide installation windows – and 25ft tidal range.

Production began at the field in November last year. Deutsche Oel & Gas planned to continue exploration drilling in the Cook Inlet this year, using the newbuild Randolph Yost jackup, in order to double the amount of gas delivered this year.

SAL Offshore opened a Delft, the Netherlands, office in 2012. It is a subsidiary of SAL Heavy Lift, a K-Line company, set up in 1980 and based in Hamburg since 2013. SAL Heavy Lift has 14 vessels and 600 crew members, plus two charter vessels.

As well as oil and gas projects, SAL Offshore has been working on renewables projects, using the 160.5m-long, Lone vessel equipped with a Kongsberg DP2 system, delivered in 2011, and also with two portside 1000-tonne cranes.

On the Wikinger Wind Farm in the German sector of the Baltic Sea, SAL Offshore transported and installed nine, 36m-long, 1.4m-diameter, up to 47-tonne test piles using the Lone in up to 40m water depth. The firm then went back 10 weeks later to perform strike and pull out tests.

At the European Marine Energy Centre, at Orkney, Scotland, the firm transported and installed on a pre-installed monopile a 220-tonne Voith tidal turbine (Voith Hytide 1000-13). This was in high cyclic tidal range through which the vessel was able to operate while remaining within its DP2 operational limitations.

The firm’s idea, for future array projects, is that it could stack 6-7 of the devices in the vessel’s cargo hold, then stay on site and install several in one go, including substructure clump weights.