The start date of the new option is aroundmid-July, which commits the rig to Maersk for continued operation in the Danishsector of the North Sea until July 2015.
Northern said the extension added roughly$52 million to its contracted revenue backlog.
Maersk first contracted the Energy Enhancerin 2011 under a one-year charter, starting in 2012, worth more than £20 million($33.1 million).
It exercised the first of three one-year optionsin April last year which added a further $48 million to Northern's contractedrevenue backlog.
