BG Group, which has a 40 percent share in the consortium that explores the BM-S52 block, is the operator during the exploratory phase. Petrobras has the remaining share in the consortium.
"This discovery had been announced (by the operator) during the drilling of the well 6-BG-6P-SPS, known as Corcovado-1," Petrobras said in a statement.
Corcovado-1 is located 130 kilometers from the cost of Sao Paulo state, in a water depth of 800 meters, the company said.
"The Consortium ... plans to continue drilling the Corcovado-1 and also drill another well in 2009, seeking to increase the knowledge about the area," it added.
If the block is considered commercially viable, Petrobras would be the operator of the consortium during the production phase.