CANADA'S Talisman Energy has stepped in to buy Arakis Energy for around $200 million in a move that will give the company a 25% stake in a project to export large quantities of oil from Sudan. Calgary-based Arakis is effectively a one-project outfit through its stake in the Greater Nile Petroleum Company, which is targeting exports of 150,000 barrels per day of crude and has proven and probable reserves of 450 million barrels.