If your wondering what sour crude is...it's the same thing as sour gas...sour means it has hydrogen sulfide(sulfur) in it. It has to be "scrubbed" from the gas or oil...this process is called sweetening. Sour vs sweet...hey...no body ever accused the oil patch of being sophisticated in their terminology or much else. :-))
"Flint Hills Resources LLC, the refining arm of billionaire brothers Charles and David Koch’s industrial empire, said it offered to pay $1.50 a barrel Friday for North Dakota Sour, a high-sulfur grade of crude, according to a corrected list of prices posted on its website Monday. It had previously posted a price of -$0.50."