China National Petroleum Corp (CNPC) has signed a memorandum of understanding with Canada's Aurado Exploration expressing interest in buying at least 51 per cent of a Kazakhstan oilfield. The potential acquisition could be the third by a mainland oil firm in Kazakhstan's North Caspian Sea project. CNOOC and China Petroleum Corp, parent of China Petroleum & Chemical, both have investments pending. China's oil companies have been stepping up their overseas investment because domestic resources are not sufficient to satisfy the country's fast-growing appetite for energy. CNPC, parent of China's largest oil firm PetroChina, had stated its interest to acquire, or 'farm in', at least 51 per cent of Aurado's Liman Block in western Kazakhstan, subject to due diligence and terms of negotiations, the Canadian company said. Aurado said the Liman Block was located about 70km north of the Kashagan discovery, which CNOOC and China Petroleum Corp were investing in. The block had so far produced about 400 million barrels of oil, while an independent Resource Potential report estimated potential resources of 708 million barrels, Aurado said. Drilling of the block began in October last year, and a capital budget of about US$20 million was planned for the block's East Tegen Cretaceous pool, which has estimated reserves of 30 million barrels.