An embargo only works if a country completely stops producing, because it loses control over the destination of the crude once the ship has left port. It would take ALL of the OPEC countries to shut in production to cause a shortage.
That would hurt us, but it would hurt all oil-importing countries. But it would hurt OPEC far worse. Most of them have crappy little economies that are completely dependent on oil revenue, and an embargo would cause them to instantly lose access to the credit markets.
Our prices would go up, but their lights would go off. It ain't gonna happen.