Pacific Drilling S.A. announced on Wednesday that one of its subsidiaries has reached an agreement with Samsung Heavy Industries to extend until February 17, 2012 an option to construct a seventh ultra-deepwater drillship.

Under the revised terms of the option agreement, the delivery of the drillship will be no later than May 17, 2014. The commercial terms of the option agreement are unchanged.

Pacific has previously said it expects the total cost, including commissioning and testing and other costs, to be about $600m, excluding capitalized interest.

Pacific Drilling, which only listed in the US in December, controls a fleet of six ultra-deepwater drillships including newbuildings.

Four have already hit the water and the other two, which are under construction at Samsung, are due for delivery in 2013.