Snøhvit pipeline laid

Work on laying the main pipeline to carry the unprocessed wellstream from Statoil’s Snøhvit field in the Barents Sea to land was completed on 4 June by the Solitaire laybarge.

Coming ashore at Melkøya outside Hammerfest in northern Norway, this 143-kilometre facility has an external diameter of 28 inches and is the world’s longest multiphase-flow pipeline.

It will allow gas from the field to be brought ashore for processing and liquefaction before being exported as liquefied natural gas (LNG).

“Multiphase transfer of the wellstream to land represents a substantial technological leap,” says Margareth Øvrum, executive vice president for Technology & Projects.

“This marks the culmination of more than 20 years of research and development.”

When the Snøhvit line becomes operational in the autumn of 2006, it will serve as a full-scale laboratory to provide valuable information on multiphase flow transport over long distances.

That in turn opens new commercial opportunities for this technology.

The actual pipelaying operation began from Melkøya on 18 April, with 12-metre lengths of line pipe welded together in a continuous process on the laybarge.

As work progressed, the welded and coated line was fed out over a stinger (ramp) at the stern of the vessel. A laying speed of roughly five kilometres per day was maintained.

Three pipecarriers have shuttled between Solitaire and Polarbase outside Hammerfest to ensure a steady supply of line pipe.

“Logistics are important when we’re laying pipe so far to the north,” explains pipelay manager Olav Hagland in the Snøhvit project.

“We have to ensure that all necessary components and people are in place as and when required.”

The next job is to dump gravel over the pipeline in order to reduce long free spans on the seabed. This work has already started.

Gas deliveries from the Hammerfest LNG plant at Melkøya are due to start on 1 October 2006.