Riser faults shut down two Statoil platforms

Offshore staff

STAVANGER, Norway -- Statoil is investigating a gas leak on its Visund field facilities in the Norwegian North Sea. The leak occurred in a riser carrying oil and gas from well A21 to the Visund platform.

On April 9, gas was observed on the sea surface near the Visund platform, emanating from a riser that had been closed for inspection. Production was at this time already shut down, however, and the leak was soon stopped.

The shutdown had been implemented the previous day specifically to inspect Visund’s risers. This followed concerns arising from studies of similar risers connected to the Njord A platform in the Norwegian Sea, which has also been shut down.

Damage had been detected in the inner layer of steel protecting the pressure barrier in some of the Njord risers. These will either be repaired or replaced.

Statoil stresses that no injuries occurred as a result of the leak at Visund, and as a precaution, all Visund personnel were evacuated to nearby installations. Once the leak was halted, they were returned to the platform, although production remains shut in pending further inspection of the risers.

“Statoil is investigating the incident, and will also support the Petroleum Safety Authority (PSA) in their investigation of this incident. Safety is our first priority, and through our investigation we wish to secure further knowledge to avoid this type of incident in the future,” said Executive Vice President for Development and Production Norway Øystein Michelsen.

Similar risers are in service at the Snorre B platform in the North Sea, although these have been inspected already, and three of the pipes replaced. There are also equivalent risers on five other Statoil-operated installations: Veslefrikk, Snorre A, Norne, Åsgard A, and Åsgard B.

However, the risers on these installations have other technical solutions and different operational conditions to those on Visund and Njord. Statoil claims that this lessens the likelihood of a change in pressure endangering the risers.

Statoil has held a meeting with Petroleum Safety Authority Norway to outline the riser challenges. The company has also appointed a taskforce to identify actions that could solve the associated problems.

04/11/2011



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