Well, you have to also keep in mind that a lot of those reserves were proven at an oil price of >$100/barrel. I don't remember offhand the numbers for what perc

Well, you have to also keep in mind that a lot of those reserves were proven at an oil price of >$100/barrel. I don't remember offhand the numbers for what percentage of proven reserves are commercially viable today, but I spoke to someone in Shell a few weeks ago about North Sea developments. He said that in unconventional plays, basically only polymer-EOR is profitable at current price levels, while ultra-deep fields, CO2-based EOR and arctic fields are generally all unprofitable. My guess is the same goes for Gulf of Mexico ultra-deep fields, as well as Brazilian pre-salt. I also know that several of the small brownfields in the North Sea are being operated now at a loss, because that costs less than plugging and abandonment. So it's perhaps not that far fetched to think that 2/3rds of current proven reserves will not be developed if the current economic situation persists.