While Simmon's is likely to be wrong on the issue Saudi reserves the insight he puts to the table is the fact that there is always a risk, including the risk (however low) that pumping a field too hard with water may damage the reserves, that is inhibit future flow rates.

Another key point is that the world will have to get used to refining poorer quality crude. As noted previously in some of Bill's musings, high prices are needed to break even on difficult extractions and difficult refining processes.

http://www.theglobalist.com/StoryId.aspx?StoryId=5275

Who wrote:

"While these claims are comforting to many oil observers the IEA’s reported crude oil imports by country of origin indicated that there had been only a modest growth in imports from Saudi Arabia from the very steady 4.5 to 4.6 million barrels per day level that had been maintained for the preceding several years.

"Little of the reported surge to 9.5 million barrels per day showed up in imports to OECD nations."

There's more to the world than the OECD!

Matt Simmons is highly respected among peak oil advocates, so if his skepticism really is based on just overlooking the developing world, I find that amazing.

And if you look at any current measure of Saudi monthly output, you'll see everyone agrees it's around 9 million barrels per day.