What is crude oil that does not contain sulfur called?

Crude oil that does not contain sulfur is referred to as sweet crude. Sweet crude is characterized by its lower sulfur content, which makes it more desirable in the refining process. This generally results in cleaner burning fuels and fewer emissions when the oil is processed and used. Sweet crude typically commands a higher market price compared to sour crude, which contains higher levels of sulfur, thus impacting the refining complexity and environmental considerations.

Sour crude, on the other hand, contains significant amounts of sulfur, leading to more extensive processing requirements to remove the sulfur compounds. Refined crude is not a standard term used in the oil industry; rather, the term generally refers to oil that has already undergone the refining process. Heavy crude refers to oil that has a high viscosity and density, making it more challenging to extract and refine. Hence, sweet crude stands out for its lower sulfur content, making it the correct answer.