SAO PAULO—Brazil's state-controlled oil company Petrobras sold stakes in a set of oilfields known as Polo Macau, located in the country's Potiguar Basin, to SPE 3R Petroleum for $191.1 million, the company said on Aug. 9.

Petrobras said the fields, both onshore and offshore, are already under production. The company also said it has started the sale process of stakes it has in 11 mature offshore oilfields in the Campos Basin, a set of assets known as Polo Garoupa.