What is crude oil composed of?

Crude oil is primarily composed of hydrocarbons, along with small amounts of oxygen, nitrogen, sulphur, and metal impurities.

Crude oil, also known as petroleum, is a naturally occurring, unrefined fossil fuel. It is a complex mixture of hydrocarbons, which are compounds made up of hydrogen and carbon atoms. These hydrocarbons can vary in length, structure and complexity, which contributes to the different properties of crude oil. The hydrocarbons in crude oil can range from as few as 1 carbon atom (methane) to as many as 60 carbon atoms.

In addition to hydrocarbons, crude oil also contains small amounts of other substances. These include oxygen, nitrogen, and sulphur, which are present in the form of compounds such as carbon dioxide, nitrogen oxides, and sulphur dioxide. These compounds can contribute to the environmental impact of crude oil when it is burned as fuel.

Crude oil also contains trace amounts of metals, primarily iron, nickel, and vanadium. These metals are usually present in the form of complex compounds and can have a significant impact on the refining process of crude oil. For example, they can cause corrosion in the refining equipment or form undesirable by-products.

The exact composition of crude oil can vary widely depending on its source. Different oil fields around the world produce crude oil with different compositions, which can affect its quality, its suitability for different uses, and its price on the global market. For example, crude oil with a high sulphur content, known as 'sour' crude, is generally less desirable than 'sweet' crude with a low sulphur content.