You also need engineers to really blow up these oil fields. It's part of the safety mechanisms of them. I'm not convinced that these people would destroy their livelihood. They'll need to keep these fields running after the war regardless of who is in power.Imagine you are an Iraqi roughneck. You work on the well. The well is wired up to incinerate you at someone else's wim. How hard would it be to "accidently" break the wire leading up to the explosives?...
Another good point.