The British Department of Energy and Climate Change said it gave an environmental permit to Total to start a dynamic kill to stop the gas leak at the Elgin platform more than 100 miles off the coast of Aberdeen.
Natural gas is leaking from above the water's surface at a rate of around 2.1 million cubic feet per day. The dynamic kill involves the use of so-called drilling mud pumped into the well.
"The dynamic kill operation is a major step for Total and offers the quickest way to stop the release from the well," the DECC said in a statement. "In parallel, work is under way to drill a relief well as an alternative solution. We continue to monitor the situation closely."
Natural gas isn't leaking into the water. Scottish scientists said fish samples revealed no levels of contamination from the Elgin leak and no natural gas has reached shore.
"The government and Total have been working hard to ensure the Elgin gas release is dealt with as quickly and as safely as possible with minimal impact on the environment," the British government said.