There were many good reasons to oppose the Iraq War, but the blood for oil slogan was particularly moronic. For a start the cost of the war has proven to be much greater than the value of any oil. But this article from Time Magazine may be of interest to those who still cling to the slogan:
Those who claim that the U.S. invaded Iraq in 2003 to get control of the country’s giant oil reserves will be left scratching their heads by the results of last weekend’s auction of Iraqi oil contracts: Not a single U.S. company secured a deal in the auction of contracts that will shape the Iraqi oil industry for the next couple of decades.
That’s one myth destroyed.