Total SA, Europe’s third-largest oil company, said a natural-gas leak that has lasted for more than three weeks in the U.K. North Sea has decreased to about one third of an initial estimate.
Flights, modeling and platform visits put the rate at about one third of the 200,000 cubic meters a day estimated after seepage at the G4 well at the Elgin platform was detected, the Paris-based company said today in a statement on its website.
“There has been no direct marine contamination” from the leak, Total also said, citing Scottish authorities on the chemical testing of water and sediment samples gathered two miles from the platform.
Total first returned workers to Elgin earlier this month to assess a leak from the G4 wellhead and study ways to halt the flow. While pumping heavy mud into the well, known as top-kill, would be “relatively easy,” drilling two relief wells could be an alternative solution, it said at the time. The top kill operation could take several weeks while drilling the relief well may last several months.
The two methods “are progressing according to plan,” the French oil company said today. The Sedco 714 drilling rig started the first relief well about 2 kilometers from the Elgin complex and another drilling rig, the Rowan Gorilla V rig, will be deployed in early May.
The West Phoenix pumping vessel and the Skandi Aker will be used for the top-kill operation, Total said. Two helicopter trips to the so-called PUQ platform this week confirmed it would be a “safe base” from which to operate.
The site is about 140 miles (225 kilometers) east of Aberdeen, Scotland, where platforms were evacuated for more than a week.
Operations to stem the leak are costing Total about $1 million a day, including hiring two rigs for drilling of relief wells and about $1.5 million in net operating income lost daily from halted production, Chief Financial Officer Patrick de la Chevardiere said on a conference call April 2.
The Elgin-Franklin fields supply about 15 percent of the Forties blend, one of the crudes used to price the Brent benchmark for more than half the world’s oil.