The high-pressure/high-temperature well will be used to block and permanently seal the Elgin G4 well – the source of the leak – in the event that a planned dynamic kill operation fails.
The semisubSedco 714 will drill the relief well around 1.2 km (0.75 mi) east of G4 in 90 m (295 ft) water depth. This will have a vertical depth of roughly 4,400 m (14,435 ft), and will take around 180 days to drill and complete.
Total continues discussions with the government on its preferred option of a dynamic kill, which would employ heavy mud to block the well.
A DECC spokesman said: “We are happy with the progress Total is making to resolve this incident as quickly as possible. We continue to monitor the situation closely and the latest reports from Marine Scotland show that the impact to the environment remains minimal.”