Under the contract extension, drilling operations are expected to commence in the third quarter of 2014, in direct continuation of the next assignment for West Alpha on the Balder field.
The extension has a firm period of two years with an estimated revenue value of $410m.
ExxonMobil has an option to extend the contract with one additional year on the same terms as the two parties have agreed for the first two years.
West Alpha has secured firm contracts that will keep the rig employed to third quarter 2016.
North Atlantic Drilling is an offshore harsh environment drilling company that has a fleet of six harsh environment units in operation and two newbuilds under construction.
