Bearded Bruce. I think resource wars are already occurring. I do not think the 1990 invasion of Iraq was purely a battle over sand dunes or ideology, or even because of the invasion of Kuwait. If there was no oil there would be no fighting over a bit of arid scrub and desert.
The same applies to the toppling of Gaddafi. The only surprise is that Saudi thus far is immune. This would be nothing to do with huge sales of weaponry to them of course.
   Prior to that Mohammad Mosaddegh was toppled in Iran in the 50's, and of coursepreviously nationalising the Anglo Iranian Oil Company(BP) had nothing to do with his fall either.