Seadrill said this cancellation was effective early May after the rig finishes demobilising from a well site.

While there was an estimated $US160 million ($A209 million) reduction to Seadrill's backlog, the company did not flag any major cash flow impacts.

"After taking into consideration the expected decrease in operational expense while the unit is cold stacked, and the fact that termination fee payments will not be impacted by downtime, Seadrill Partners does not expect a material impact on its cash flow position over the contract period through July 2017," the drilling company said.