I don't think you are getting the point. That's a far too simplistic an analysis.
Put it this way, had the invasion not taken place, and Saddam Hussein had maintained his gamesmanship over supply and the Hormuz issue, gas prices could have caused a serious global meltdown. He controlled 10% of the global oil supply, at any point he could hold a gun to the head of the global economy, so if we want to talk in hypothetical, had it not taken place we could have been paying $100 per gallon (exaggerated to make the point).
Do you see what I am getting at? It wasn't done to win contracts and physcially capture the oil fields, it was to make sure supply of oil from Iraq stayed high or increased to avoid supply problems which were shocking the global economy, done under the guise of freedom and liberation. This has been verified by people in the Bush administration at the time.
I really think it would make more sense if you spent just 15 minutes to watch the opening section of the video.