A new-build Keppel FELS N Class Plus, together with equipment and personnel, will be used for the field.
Final specifications of the rig are still being negotiated prior to construction commencing at the Keppel FELS yard in Singapore.
The Bentley oil discovery is located in block 9/3b in the UK North Sea, 160km east of the Shetland Islands on the western-edge of the Viking Graben.
COSL will work with all of the important stakeholders to develop field specific rig and drilling services.
Xcite Energy CEO Rupert Cole said: "COSL has considerable experience in drilling operations and we believe they possess the skills and expertise to work alongside our other partners in our collaborative and innovative model.
"Selecting this ultra-high specification drilling rig and constructing it at the Keppel FELS yard in Singapore is an important part of securing both the future schedule and drilling efficiency of the Bentley project."
Block 9/3b was awarded to Xcite Energy in October 2003.
BP signed a contract with Xcite Energy in January 2010 to market and distribute the crude oil extracted from the Bentley field, which was discovered in 1977.
Meanwhile, Xcite Energy also recently signed a MOU with Baker Hughes for the Bentley field. The MOU may include the supply of drilling and completion services, well engineering, electronic submersible pumps and reservoir engineering.