In past years, most oil sands projects were either cancelled or put on hold as majors including Royal Dutch Shell Plc and ConocoPhillips sold their operations to local producers.
Brazilian authorities and companies involved with river water management are trying to stop the torrent of mining waste from reaching the Sao Francisco river, a source of drinking water for communities in five of the country's 26 states.
The country’s once vibrant exploration activity plummeted after Chavez came to power in 1999 and nationalized foreign companies’ mining licenses and assets.