May 18, 2012. Vale SA, the world's largest iron-ore producer, hired Bank of Nova Scotia and Citigroup Inc. to sell its oil and natural gas assets in Brazil as it focuses on metals production. The Rio de Janeiro-based company's stakes in the oil fields, located both within Brazil and offshore, may be worth as much as $1 billion. The company expected to finish by the end of June a study on whether to sell its oil and gas unit. The company won't take part in any new oil block auctions in Brazil or elsewhere. Vale entered the hydrocarbon exploration business in Brazil in 2007 and has stakes in both onshore and offshore blocks. Vale said in 2010 that it certified oil and natural gas resources equivalent to 210 million barrels of oil, with potential to produce 58,000 barrels a day in 2017.