By Phaedra Friend Troy
Just after 8 on the morning of April 9, a gas leak was reported at the Statoil-operated Visund platform in the Norwegian North Sea. Statoil (NYSE:STO) mobilized its emergency response team immediately and informed the appropriate authorities.
On April 8, Statoil shut-in production from the Visund field to perform inspections on the risers as a precaution. Damage to the inner layer of steel that protects the pressure barrier was detected at some of the risers at Njord, which shares design and operational similarities.
Located on Blocks 34/8 and 34/7 in the Tampen area of the Norwegian North Sea, the Visund development comprises a floating production, drilling and quarters platform. The subsea wells are connected to the production facility via flexible risers, and these steel pipe risers deliver oil and gas from the production wells to the Visund platform.
Production started at Visund on April 21, 1999, and in addition to Statoil as the operator, project partners include Petoro, ConocoPhillips and Total.
Gas Leak Stopped
On April 9, gas was observed on the sea’s surface near the Visund platform, escaping from a leak in a riser that had been closed for inspection.
The 63 non-emergency personnel were evacuated to nearby facilities, including the Gullfaks C and Safe Scandinavia, and no injuries occurred.
The natural gas leak occurred in a riser carrying oil and gas from well A21 to the platform. By 1:00 in the afternoon, the leak was stopped; and because production was already shut-down, the volumes that were leaked were minimal. Evacuated Visund staff has returned, although production remains shut-in.
Statoil is currently investigating the hydrocarbon leak.
“Statoil is investigating the incident, and will also support the Petroleum Safety Authority (PSA) in their investigation of this incident,” said Oystein Michelsen, the executive vice president for development and production in Norway. “Safety is our first priority, and through our investigation we wish to secure further knowledge to avoid this type of incident in the future.”
The Snorre B facility also has similar risers to Visund and Njord, but those risers have already been inspected, and three of them have been replaced.
Additionally, Statoil operates five other facilities where similar risers are used in the development, including Veslefrikk, Snorre A, Norne and Asgard A and B. Because these risers have other technical solutions and operational conditions, the chance that the change in pressure that led to the damage occurred is diminished.
Statoil has conducted risk assessments of all the risers on the other platforms and does not consider them to be in any danger. Nonetheless, the company is reevaluating the risk assessments in light of the Visund incident.
Statoil detects, stops gas leak at Visund in the Norwegian North Sea
By Phaedra Friend Troy