The boom in U.S. crude oil production has been a game changer in terms of handling and refining crude oil as well as supply. This is impacting the market as are several other factors.There are many type of crude oil produced around the world with differing quality characteristics. The two most important qualities that define crude oil are density and sulfur content. Density is described as heavy or light and from high to low. Sulfur content is described as sour or sweet and also from high to low. Over the years, U.S. refineries have been built to handle a certain type of oil, much of it imported and heavy. Then came the U.S. oil boom with a lighter and sweeter type than the kind that the U.S. refining capacity (built up over decades with bi...