BG Group along with its partners at Petroleo Brasileiro -- Petrobras -- submitted a declaration of commerciality to the Brazilian National Agency of Petroleum, Natural Gas and Biofuels.
"The (declaration) marks the start of the production phase for the Guara field and is another significant milestone in the development of BG Group's large and high-quality discoveries in the pre-salt Santos Basin," the company said in a statement.
Four wells were drilled in the area. Petrobras said there was an estimated 2.1 billion barrels of oil equivalent in the region, which BG Group dubbed the Sapinho field.
An estimated 50 billion barrels of oil lies off the country's coast, a volume that's expected to put the Latin American country on par with some of the world's top oil producers.
After Chevron was penalized by the Brazilian government for a recent offshore oil spill, the country's environmental secretary said the government needs to put pressure on oil companies now to handle an expected oil boom the right way.