I think he is saying that based on how much oil has been used in the past, what our current usage is, and how much oil has been discovered lately the odds of any(or many) more Saudi type discoveries are pretty slim. Based on these figures he making an estimate of how much oil is remaining.

Granted there has just been a reportedly 'Saudi' size discovery off the Amazon it will probably 10 years before the infra-structure will be in place to allow pumping the amounts of oil that the Middle East can deliver. All the while the Middle East oil is running out so that when the Amazon comes in its full capacity will only make up the Middle East loss. While we are waiting the world's oil consuming populace (China, India, Brazil, etc.) is growing like mad.

In all this gnashing of teeth about oil prices the one thing that you don't hear much about is conservation. Smaller cars, less trips, carpooling, driving slower, etc. are rarely mentioned. All this hoopla about ethanol has lead to an increase in both fuel and food prices. To see how shaky the ethanol production chain is take a look at what the flooding in the corn belt did to the price and availability of corn.

Very soon the oil and natural gas prices are going to make nuclear energy look very appealing.