The way people discuss oil prices in popular media makes it abundantly clear that they have no damn idea what they're talking about.
Oil is a global commodity. It goes to the highest bidder. It will always go to the highest bidder, because if it went to anyone else that person who values it at less than the highest bidder values it would have the incentive to sell it to the highest bidder. The way that oil plays out in wars and politics is not a matter of who gets the oil, it's a matter of how much oil is released onto the market. This is why anyone who complains about things like the U.S. exporting oil to other countries amidst high gas prices is an idiot.
So now let's talk about Iraq. How much oil did the U.S. get from Iraq? It turns out not very much because Iraq is now selling a huge amount of its oil to China. But guess what that means: Now China can satisfy its demand for X barrels of oil from Iraq and doesn't have to get it from Venezuela or Russia or Saudi Arabia or the U.S., which means the U.S. can get that oil which China didn't need to buy. Because it's a global commodity.
The real question you have to ask is whether the amount of oil Iraq is currently releasing onto the global market is more or less than it would have been under Saddam. But determining that requires quite a lot of speculation, and it isn't even clear that lower short term global oil prices are even in the interest of the United States.
"...Oil fields contracted include the "super-giant" Majnoon Field, Halfaya Field, West Qurna Field and Rumaila Field." [1]
If you look up each of those fields, you'll see they are licensed to Shell, BP, and Exxon [2] [3] [4] [5]
Given all of those companies have a strong presence in the US and definitely have lobbying power. I'd say the US got effective control over one of the largest oil reserves in the world.
- West Qurna: ExxonMobil, Shell, Lukoil, Statoil, Eni SpA, CNPC, Petronas
- Rumalia: BP, CNPC
- Majnoon: Shell, Petronas
Of all these, only ExxonMobil is an American company. Shell and BP are not American, regardless of the presence, unless you want to call Exxon a British or a Dutch company as well.
But more importantly, all these contracts were awarded on a competitive basis, with a bidding process. Especially telling is an entry for Rumalia field: "ExxonMobil which also bid on servicing this field at a price $4.80 walked away due to price cutting terms by the Iraqi Government leaving BP and CNPC as winners of the contract.".
You don't have to be an American company to benefit from American policy. And I'm sure congressmen benefit from the "non-american" oil companies.
The question I would like to know the answer to, is who was drilling the oil before the war... it seems unclear, but if it was Iraq (national companies) then the war was defiantly an oil grab.
I doubt CNPC, Lukoil, Petronas, Statoil, and others were in collusion with the Bush administration to invade Iraq and gain control over its oil by competitively outbidding each other in the end.