Attention: Oil Is Fungible
There is currently a battle between Venezuela's infamous ruler Hugo Chavez and the company of Exxon. Chavez has nationalized Exxon's assets in Venezuela, which prompted Exxon to retaliate by seeking court orders freezing Venezuelan assets in other countries. Chavez is so upset by this response from Exxon that he has now threatened to cut of oil exports to the United States, a threat which is now causing the market to bid up the price of oil.
What Chavez fail to grasp is that the only way this is going to have any affect at all on the U.S. is if he refrains from selling the oil he now sells to the U.S. to anyone, which is to say if he sharply reduces overall exports and production of oil.
And even then he will hurt himself a lot more than he hurts the U.S. as his socialist state is dependant for its survival on oil revenues while the U.S. would only be slightly damaged by this (And they would really be no more damaged than other oil importers such as the EU, Japan and China). If on the other hand (as seems likely) he starts selling that oil to someone else, all this will mean is that some other oil importer will buy less from other oil exporters. These other oil exporters will then sell their oil to the U.S., causing no net change at all in the U.S. access to oil.
It is perhaps not surprising that someone like Chavez doesn't understand such basic economic principle. Slightly more surprising is the fact that market participants does not seem to understand it.