It depends on how quickly they can begin to cut costs. I would suggest looking at where their drill sites are located and the average age by area. This will allow you to gain some idea of the average cost per barrel and then see where BP would be left if oil hits US $20. People who think the price will rise due to increased demand do not understand how much oil Saudi Arabia can sell. Their wells are profitable at around US $8 (although the national budget is only balance at around US $80). Shell, historically, have been much more successful at cutting costs and have already begun to diversify away from oil faster. Ironically, whilst low oil prices may encourage consumption increases it may lead to the oil majors abandoning projects reducing global supply. Saudi Arabia has always planned to be the last place pumping oil and they may just get that wish at 12.3m bpd.