Anglo-Dutch energy giant Royal Dutch Shell said on Wednesday that it has sold a large stake in an offshore Brazilian oil field to Qatar for about $1.0 billion.Shell said it has agreed to offload a 23-percent interest in the Parque das Conchas (BC-10) project offshore Brazil to Qatar Petroleum International. The deal remains subject to regulatory approval in Brazil.The group will continue to operate the oil field, which currently produces 50,000 barrels of oil equivalent per day.Shell added that it will retain a "significant" upstream presence in Brazil.