Contrary to what appears to be popular belief in the media, the “peak oil” concept is not about the amount of reserves, it’s about flow rates. IE, it’s not how much oil is underground, it’s how many barrels can be produced/processed on a daily basis.
The processing required for shale oil as well as tar sands makes them different from the good old days where the Saudis could just turn a valve and increase the flow rate (which they still can do on some fields, but this is just on a small marginal proportion of total supply). They also have much greater environmental impact, to the extent that ramping them up too much would cause other problems.
So shale/tar sands may represent a vast reserve of oil in the ground, but it’s questionable as to whether they can replace the flow lost from declining conventional oil sources.
I am not an “expert” either but this is my understanding from reading/talking to people who are. (For those who wish to know more, try http://gregor.us/ — this is a blog written by Gregor Macdonald, a great energy analyst in addition to being a brilliant macro analyst imho).
