The Hibernia platform has been shut down following an oil spill.
12,000 litres of oil have spilled into the ocean off the coast of Newfoundland.
Production has been halted until the problem can be fixed.
Both oil and water discharged from a storage cell on Wednesday.
The production platform Hibernia is the world's largest oil platform by weight.
Inside the gravity base structure are storage tanks for 1.3 million barrels (210,000 m3) of crude oil.