Light and heavy crude oil
Heavy or extra heavy oil refers to crude oil that does not flow easily. Typically, heavy oil is oil with an API grade of less than 20. Heavy crude oil is crude oil that has a high concentration and does not flow easily in the oil extraction well. This type of oil is called "heavy" because its density and relative density are higher than light crude oil. In the strict definition, any type of liquid crude oil whose API density is lower than 20° is called "heavy crude oil".
Heavy crude oil is closely related to bitumen or oil from oil sands. In petroleum geology, oil obtained from oil sands is classified as extra heavy oil. Heavy and extra-heavy crude oil are similar to the residue left over from the refining of light crude oil. Their difference with their light counterparts is high density, stickiness at tank temperature, high percentage of sulfur, nitrogen, oxygen and heavy metals. The amount of heavy and extra heavy crude oil reserves in the world is more than twice that of conventional crude oil, and the largest reserves of heavy and extra heavy crude oil in the world are in Canada and Venezuela. The cost of extracting and refining this heavy crude oil is more complicated and expensive, and for this reason, their price is lower than light crude oil and they have fewer customers.
