What term is used for crude oil that contains a lot of sulfur?

Crude oil that contains a significant amount of sulfur is referred to as sour crude. The term "sour" specifically indicates that the crude oil has a higher sulfur content, typically over 0.5% by weight. This characteristic affects the oil's odor and has implications for its refining process, as the presence of sulfur can lead to the production of sulfur dioxide, a harmful pollutant when the crude oil is burned or processed.

In contrast, sweet crude contains low levels of sulfur, usually under 0.5%, making it easier and less expensive to refine into valuable products like gasoline and diesel. Light crude and medium crude refer to the viscosity and density of the oil, not its sulfur content, with light crude being less dense and flowing more easily compared to the thicker or denser characteristics of medium crude. Therefore, the classification of crude oil is crucial in determining its market value, refining requirements, and environmental impact.