The fractional reserve Federal reserve banks have a vested interest in seeing oil sold in petrodollars because they are always getting the interest payments on the credit they create out of thin air. Even if they have to put some of what they profit via usury back into the Treasury they control the economy through their decisions only they know about. The petrodollar derives its valuation from the sale of most Middle East oil in Fed Reserve dollar notes. Any country in the Middle East not participating in the petrodollar system tends to have the combined military forces of the Arab dictatorships and the USA covertly invading it and surrounding it militarily. Think Iraq, Libya and now Syria and Iran.
The demand for Fed petrodollars is always increasing so long as the demand for oil sales is also increasing or the price per barrel of oil can be manipulated up if demand is down, like it currently is.
Thanks to the petrodollar the USA has a welfare and a warfare State. The welfare is from the taxpayer to the bankers. Because of the petrodollar most manufacturing, steel factories and auto industry has been offshored and outsourced to cheaper places. Look at the effect on the economy of the USA which is fast getting all the wealth transferred to the elites and fast becoming a third world population with a third world economy. I would say the usury Federal Reserve fractional reserve bank credit combined with the demand for the petrodollar is ripping the society and culture of the USA to shreds. The politicians and the big banks are in bed together stealing all the wealth of the people via welfare to the bankers to socialize their gambling losses thereby impoverishing the taxpayer and at the same time forcing the international community to use the petrodollar. So the Fed bankers always have the strong position of the demand for petrodollars to back up their theft of the taxpayer via usury and cooperating bought off politicians. The only people benefiting from this setup are the Fed bankers, their friends who receive the banker welfare and the politicians who are going along with the taxpayer theft.
The country is being reduced to poverty and debt slavery thanks to the Fed bankers and their main tool is the petrodollar. Until the people of the USA demand an end to the banker welfare state/ warfare state that the elite banking military industrial complex has insisted upon the country is doomed to destruction via debt slavery.
Look at how they have stolen our once free elections by using electonic voting machines so they always get the politician they want elected who will keep the Fed banker welfare intact and they remain in control of our destruction. Free elections are history with electronic voting machines.
See the links on the petrodollar: http://www.caseyresearch.com/cdd/demise-petrodollar