Complex sentence: Recent estimates have pushed the total estimated barrels of oil equivalent (BOE) to greater than 30 billion, though Petrobras has not confirmed the highest estimate, but these estimates are being put into severe doubt by impartial analysts.
Split into simpler sentences: Recent estimates have pushed the total estimated barrels of oil equivalent (BOE) to greater than 30 billion, though Petrobras has not confirmed the highest estimate. These estimates are being put into severe doubt by impartial analysts.