Terribus has voiced some facts here; don't know who started that "the war is about oil" nonsense.
The only way the U. S. could take over the Iraqi's oil would be by making them a colony (with all the expense that would entail).
As Terribus writes, and I posted last June, the agreements are for service contracts; the oil companies will receive a reasonable payback, but will not 'own' the oil. The fields were poorly maintained and under developed; 'servicing' them will be expensive.
Still many problems. The Kurdish area has made some deals, mostly with a Norwegian consortium, but the Iraqi government has opposed them. Continuing bomb attacks will slow development is some areas.