The contract involves drilling four wells, which could earn the Ocean Guardian $19.6m in revenue.
Desire has obtained options to drill six more wells for itself or its partners.
After a scheduled shipyard work programme, the rig will mobilise from North Sea waters late next month. The first well is likely to spud in the North Falkland basin in February 2010.
AGR Petroleum Services will oversee well construction, technical work and operations management.