Sour crude oil iscrude oil containing more than 0.5%sulfur impurities (by weight).[1] The impurities need to be removed before this lower-quality crude can be refined intopetrol, thereby increasing the cost of processing. This results in a higher-priced gasoline than that made fromsweet crude oil.[1]
Current environmental regulations in the United States strictly limit the sulfur content in refined fuels such asdiesel andgasoline.
The majority of the sulfur in crude oil occurs bonded to carbon atoms, with a small amount occurring as elemental sulfur in solution and ashydrogen sulfide gas. Sour oil can be toxic and corrosive, especially when the oil contains higher levels of hydrogen sulfide, which is a breathing hazard. At low concentrations the gas gives the oil the smell of rotting eggs. For safety reasons, sour crude oil needs to bestabilized by having hydrogen sulfide gas (H2S) removed from it before being transported byoil tankers.[2]
Since sour crude is more common than sweet crude in the U.S. part of theGulf of Mexico,Platts has come out in March 2009 with a new sour crudebenchmark (oil marker) called "Americas Crude Marker (ACM)".[3]Dubai Crude and Oman Crude, both sour crude oils, have been used as a benchmark forMiddle East crude oils for some time.
The major producers of sour crude oil include:
