Total said it had stopped the gas leak at its Elgin platform in the North Sea, seven weeks after it was discovered.
The French oil major said it pumped heavy mud into the G4 well to stem the flow of gas. The intervention began on May 15 and 12 hours later the leak was plugged.
Total’s head of exploration and production, Yves-Louis Darricarrère, said it was a “major turning point”. “Our absolute priority was to stop the gas leak safely and as quickly as possible,” he said.
“[Total would] complete the ongoing task and take into account the lessons learnt from this incident.” He did not say when output would resume at Elgin.
Plugging the leak will be a relief for Total, for which the Elgin outage was just one of a series of incidents that have hit production this year.
It also suffered an attack on a pipeline feeding its liquefied natural gas plan in Yemen and technical problems at an onshore gas well in Nigeria.
The leak was detected in March during operations to seal G4, a well that had suffered several incidents during the past year. Total had to power down the Elgin platform and evacuate its 238 employees.
Initially there were fears the leak could lead to a massive blowout similar in scale to the Deepwater Horizon disaster in the Gulf of Mexico in 2010.
But the threat of an explosion receded and Total said that from an estimated initial gas flow rate of about 2kg/second, the leak had gradually decreased to 0.5kg/s.
The well will be monitored over the next few days to ensure the operation was a complete success, after which work can begin to permanently plug and abandon G4.
Charles Hendry, UK energy minister, said stopping the leak was “clearly excellent news. . . the government has been working closely with Total throughout this incident to resolve it as quickly and safely as possible with minimum impact on the environment”.
Mr Hendry said he would continue to monitor the success of the operation to ensure the well could be safely and permanently secured.