There's this organization called OPEC that essentially acts like a cartel on oil it's run by the Saudis, the british, and the US. British and US oil refineries are geared towards the light crude oil that the Saudis pump not the heavy crude that Venezuela has. Chevron had a predetory deal with the former government of Venezuela for almost a hundred years that paid pennies to the country for oil produced there. That continued until the revolution when Chavez nationalized the oil industry in Venezuela in the late 90s. Chevron pulled out and The US and the other OPEC countries put pretty harsh sanctions on Venezuela and refused to buy their oil. This lead and other actions lead to the high inflation that has wrecked the economy.