The internal investigation launched by Statoil following the loss of control over a well on the Snorre A platform in the North Sea on 28 November 2004 has been completed.
“Safe operation is a precondition for all our activities,” says Terje Overvik, executive vice president for Exploration & Production Norway.
“Our inquiry shows that we’ve failed to live up to our own targets. We must learn from this incident.
“Our job now is to ensure that work processes and management systems on Snorre are observed, so that we can avoid a similar incident in the future.”
The direct cause of the gas leak was a suction effect which arose when an extra length of casing was pulled out and drew gas from the reservoir into the well.
Passing via an external casing section which had suffered wear damage, the gas then escaped into the formation and out to the seabed.
According to the inquiry report, the underlying causes of the incident were inadequate planning and appreciation of the risk, as well as a failure to observe governing documentation.
The potential in the incident lay in the gas volumes which leaked out, and which could have been ignited.
“We’re now adopting the measures needed to strengthen and follow up drilling and well activities on Snorre,” reports Mr Overvik.
“We will ensure that sufficient attention is paid to governing documentation and best practice for drilling and well operations.”
After the incident, Statoil took immediate steps to stabilise the well and establish adequate barriers. Work was also done to document that the tension leg platform was securely tethered. The subsea template is still under investigation.
“With hindsight, we can say that the organisation responded extremely well to the emergency,” says Mr Overvik. “But this was a very serious incident which, in the worst case, could have caused major harm to people, the environment and material assets.”