A hot-tap operation carried out last week has prepared Statoil's Statpipe gas trunkline for tie-in of an export line from its Gullfaks field.
The work was done for the Gullfaks satellites phase II export line (GFSE) project by divers from Seaway Osprey, operated by the Stolt Rockwater Joint Venture.
A 30-centimetre hole was drilled into Statpipe through a welded T joint with a shut-off valve in 135 metres of water, without halting the gas flow – hence the term "hot tap".
The drill was then withdrawn and the valve shut until the Gullfaks export line is tied in later this autumn, reports GFSE technical manager Olav Hagland.
Tie-in to the Gullfaks A and C platforms and pressure testing will also be required before the new link can become operational.
Extending 35 kilometres, the Gullfaks export system was laid this summer. It will run from the A platform to Statpipe and back to Gullfaks C in a loop.
This North Sea link will be very important for Statoil as a gas exporter and for its Kårstø gas treatment complex north of Stavanger.
Within a few years, Gullfaks is set to account for more than half the gas reaching Kårstø through Statpipe.
The hot tap was only the second of its kind off Norway. Statoil also handled the first operation in 1998, to tie Esso's Jotun field to Statpipe.