Is There a Difference Between Crude Oil & Petroleum?

Hydrocarbons

• Hydrocarbons are organic chemical compounds of carbon and hydrogen, and may be in a gaseous, liquid or solid phase. Carbon always forms four chemical bonds, while hydrogen forms but one. The simplest hydrocarbon is methane, with a single atom of carbon bonded to four atoms of hydrogen. Ethane has two carbon atoms, each bonded to each other and three hydrogen atoms each. Hydrocarbons can get larger and more complex as the number of carbon atoms increases. Carbon atoms may double- or even triple-bond to one another, and a single carbon atom may be bonded to three or four other carbon atoms, producing branched chains. These hydrocarbons are used in myriad industrial applications in addition to their use in fuel. The hydrocarbons derived from crude oil are the basis of the enormous array of plastics that are essential to virtually all aspects of modern life.

Crude Oil

• Crude oil contains a mix of hydrocarbons in the liquid phase. Some of these may consist of very large molecules with many carbon atoms, while others have fewer, but they must be liquid in natural underground reservoirs and remain liquid at atmospheric pressure to be included as constituents of crude oil. Liquids produced at natural gas processing plants are not included under the category of crude oil. Crude oil is refined to make many different products, including heating oil, jet fuel and, of course, gasoline.

Classifying Petroleum

• Petroleum includes crude oil as well as related liquid hydrocarbon mixtures and petroleum products. Liquid hydrocarbons produced at natural gas refining facilities are included under the category of petroleum, but these are not considered crude oil. Petroleum is the broader term. Crude oil is petroleum. Petroleum is not necessarily crude oil.

Gasoline

• Although the British use the term "petrol" to describe the liquid they put into their automobiles, "gasoline" is a more specific term for a highly refined substance. Gasoline is a mixture of hydrocarbons with varying numbers of carbon atoms and some additives. The specific blend of hydrocarbons in gasoline is designed to produce the qualities appropriate for the spark-ignition engines in which they will be used. Similar fuels refined from crude oils include kerosene, diesel fuel and heating oils. All these petroleum products begin as crude oil but are refined to produce the blend of hydrocarbons appropriate to their intended application.