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Record bundle tow

May 9, 2000, 12:30 CEST

The first half of the longest and heaviest flowline bundle ever transported in the North Sea was launched in Scotland today, 9 May.

Almost seven kilometres long and weighing 9,000 tonnes, the bundle will be laid from Statoil's Gullfaks C platform to its Gullfaks South satellite.

It comprises a set of lines for wellstream, gas injection and hot water as well as various control cables, all contained in an outer pipeline.

Launching the bundle took more than 24 hours, explains development manager Morten Krogh. Balancing it in order to float correctly requires a further day.

Six vessels are involved in the tow – two tugs in front and one behind, a guard boat in the middle to prevent other ships colliding with the bundle, a workboat, and an installation and service vessel.

"Although we have experience of towing big pipelines in the North Sea, this operation is more critical because of its big dimensions and the contents of the bundle," says Christian Holst, project manager for subsea production in the Gullfaks satellites phase II development.

"We have to ensure that the bundle isn't stressed or bent beyond defined values by currents and waves, since that could damage it."

Plans call for the 470-kilometer tow from Scotland to the field to take 10 days. The vessels will then return to fetch the second virtually identical section.

Gullfaks C and A are due to process roughly 50 billion cubic metres of gas from Gullfaks South between the autumn of 2001 and 2015. That will almost double gas production from Gullfaks.