Cairn Energy has started its summer drill programme off the coast of West Greenland with the Alpha prospect (Alpha-1) in the Sigguk Block, about 175km offshore Disko Island.The Edinburgh-based oil company, which only received formal approval from the Government of Greenland two weeks ago, is targeting the Alpha and T8 exploration prospects which lie in water depths of between 300 and 500 metres.It will take 55 days to drill to 4,200m at Alpha and 38 days to get down to 3,250m at T8, the firm estimates.An update on the drilling operations will be provided in August.Cairn, which struck big in Rajasthan in the north west of India six years ago, has high hopes for its Greenland campaign. In 2007, Cairn signed licence agreements for two blocks off West Greenland (Sigguk and Eqqua) and farmed into two blocks operated by Canada's EnCana (Atammik and Lady Franklin). The following year, the London-listed firm was awarded a further four blocks in South Greenland (Kingittoq, Saqqamiut, Salliit and Uummannarsuaq), then, in 2009, it sold a 10% interest in its six operated blocks offshore Greenland to Malaysia's Petronas. The US Geological Survey (USGS) thinks prospects are good. "The extensive Arctic continental shelf may constitute the geographically largest unexplored prospective area for petroleum remaining on earth," it has said.