French oil giant, Total, gave its version of the causes of the major North Sea natural gas leak, which shut down production on the company’s flagship Elgin-Franklin North Sea field for almost a year.
At the time of the leak, in March 2012, gas from the Elgin-Franklin complex accounted for about seven percent of British production.
The leak last March had been due to corrosion stress cracking caused by a reaction between grease on the threads of the well casing and bromine used in the fluid inside the well, said Patrice de Vivies, the company’s senior vice president for exploration and production for northern Europe.
In addition, a gas layer called Hod, which was 1,000 meters or about 3,300 feet above the Fulmar gas layer tapped by the well, unexpectedly began producing oil and gas, possibly because production of the lower layer affected it. He called this set of circumstances “unique.”
“It is impossible to forecast this type of incident,” de Vivies said.
Total evacuated 238 workers from the Elgin platform, about 240 kilometers or about 150 miles from Aberdeen in Scotland, after they found the leak. The platform serves a complex of fields. There was a danger the gas could catch fire, leading to a catastrophic incident. The well, known as G4, ended up plugged about two months later. The incident caused no injuries.
At the time of the shutdown, Elgin-Franklin was producing the equivalent of 140,000 barrels of oil per day in gas and liquids, making it a very large field.
de Vivies said the company had submitted plans late last year for restarting the field and it expected British authorities to accept them shortly. The company then plans to bring the field back online gradually, starting with four wells compared to 14 at the time of the incident. He said he expected production by year-end to be 70,000 barrels per day, or half of what it was at the time of the leak. By 2016, the company’s should take production levels above 140,000 barrels per day, he said.
Total had learned lessons from the leak in a field in which the gas is under high pressure and high temperature, and that the company would be more conservative about how it operated in the future, de Vivies said. He also said Total would share its findings with other companies to avoid a repeat of this type of incident.