Ocean Rig, which is 73.7% owned by DryShips, is planning to order five new drillships at Synergy Group yards near Rio de Janeiro, Brazil, and charter them to Petrobras.
The company said that the vessels will cost about $800m each.
The vessels will be chartered to Petrobras for 15 years for about $630,000 a day.
Ocean Rig UDW drilling unit offered the lowest bid to rent out five new drillships to Brazilian state oil company Petrobras.
DryShips, through its Ocean Rig unit, owns and operates nine ultra-deepwater drilling units, including two ultra-deepwater semi-submersible rigs and seven ultra-deepwater drillships.