PBR has basically same production as XOM, while operationally not as efficient, that will improve over the years and this should trade closer to a 50% discount to XOM, which is 4x today's market cap=mid $30's valuation. With greater proven reserves, one could say it may trade at par a few years later bringing it to that $50-60 high.
baderocks2
⋅
for such a long-term prediction, that is a bold move!