Cairn Energy has agreed a contract to tie-up two drilling vessels for its 2011 exploration programme offshore Greenland.Subject to approval from the government of Greenland, Cairn intends to drill up to four wells in 2011. Cairn has also entered into a stand-by secured revolving debt facility of $900m that will also provide funding for general corporate purposes. The two vessels are the "Leiv Eiriksson", a fifth generation semi-submersible drilling rig and the "Ocean Rig Corcovado", a sixth generation drillship. Both drilling vessels are operated by Ocean Rig. "By contracting two vessels for the Greenland exploration programme Cairn has increased operational capability and flexibility and continues to demonstrate its focus on safety," Sir Bill Gammell, Cairn's chief executive said.The firm has had limited success so far with its Baffin Bay exploration programme. It last exploration well in the region, T4-1, turned up dry and followed a similar outcome for the T8-1 well, while drilling at Alpha-1S1 stopped at the end of September. The latest failure cost Cairn $185m, although at the time the company said it remains "extremely encouraged" by the early stage drilling.