Ensco has entered a $120m charter contract for an ultra-premium harsh environment jack-up rig with Nexen Petroleum.

Under the terms of the contract, Ensco 120 will be employed to drill ten wells in Nexen’s Golden Eagle development in the central North Sea.

Nexen may extend the term through 11 one-well options, which would increase the contract’s value by an estimated $140m.

The Ensco 120 series of jack-ups is being built by Keppel FELS at its shipyard in Singapore.

The 150-seat drill rig will be delivered in the second quarter of 2013.