The rise of China has changed the dynamics of the global oil market, as have increased domestic supplies of oil in the US due to the use of fracking techniques. Your comment assumes that governments act rationally in order to maximize their economic advantages, but we know that this is not true, as can be attested by the Bush Wars against Iraq and Chavez's behavior in Venezuela. There are geostrategic concerns that affect the behavior of states as much as purely financial considerations. And to what degree can the global market be considered an "open" market? I don't know. Please tell.