Oil - Types Of Oil

While crude oil is usually dark when it comes from the ground, it may also be green, red, yellow, or colorless, depending on its chemical composition and the amount of sulfur, oxygen, nitrogen, and trace minerals present. Its viscosity (thickness, or resistance to flow) can range from as thin as water to as thick as tar. Crude oil is refined, or chemically processed, into finished petroleum products; it has limited uses in its natural form.

Crude oils vary in quality. "Sweet" crudes have little sulfur, refine easily, and are worth more than "sour" crudes, which contain more impurities. "Light" crudes, which have more short molecules, yield more gasoline and are more profitable than "heavy" crudes, which have more long molecules and bring a lower price in the market.

In addition to crude oil, there are two other sources of petroleum: lease condensate and natural gas plant liquids. Lease condensate is a liquid recovered from natural gas. It consists primarily of chemical compounds called penthanes and heavier hydrocarbons and is generally blended with crude oil for refining. Natural gas plant liquids are natural gas liquids that are recovered during the refinement of natural gas in processing plants.