What is the Difference between Oil and Gas

Oil and gas are derived from petroleum hydrocarbon compounds, each bearing its own set of properties. Although they originate from the same source, the many members of the oil and gas family have differences which can be seen in their chemistry, refinement, and uses.


When oil exploration is successful, petroleum, also called crude oil, is located and removed from the ground or the ocean floor. Petroleum contains combustible hydrocarbons, which are molecules made up of hydrogen and carbon atoms. Many different types of hydrocarbon molecules exist together in crude oil, each with different structures, lengths, and boiling points. The goal of the oil and gas industry is to best exploit the properties of the hydrocarbons. Through this quest, scientists have developed methods to extract and cluster the molecules into groups based on the number of carbon atoms contained in each one.

The Refinement Process

During the oil and gas refinement process, crude oil is heated, which causes it to vaporize. Each type of hydrocarbon molecule in the crude oil has its own unique boiling point which facilitates the process of separation. As the heated vapor cools, it condenses through a distillation process based on temperature. The heavy hydrocarbon molecules with the highest number of carbon atoms condense into compounds that will become lubricating oil, fuel oil, grease, diesel fuel oil, and wax. The lighter molecules with fewer carbon atoms condense into compounds that will become gasoline, kerosene, propane and butane.

Difference between Oils

Not only are there differences between oil and gas, there are differences between oils, and differences between gases. The number of carbon atoms in a hydrocarbon molecule determines what the end product will be and what properties it will have. Oil that is used for lubricating an engine is different from oil which is burned for heating. Lubricating oils have high viscosity (thickness or stickyness) sometimes enhanced with additives. Grease is an example of an oil with extremely high viscosity. Heating oils are low viscosity liquid fuels (less thick). The molecules of highly viscous oil have more carbon atoms than those of low viscosity oil.

Difference between Gases

Gasoline is a liquid fuel, whereas natural gas (methane), naphtha and butane are vaporous gases. Molecules of methane contain 1 carbon atom; molecules of gasoline contain 4-10 carbon atoms. Although gasoline powers the majority of cars and trucks on the highways, natural gas can be used to power motor vehicles too. It burns cleaner with fewer emissions, but since it is a vapor, it is more difficult to store and transport. Gasoline can only be obtained through the crude oil refining process. Natural gas is also a by-product of refining, but often it is found with crude oil during oil exploration and can be pumped out of the ground and used as it is, with minimal processing.

Understanding the differences between oil and gas begins with understanding the similarities. The different sized hydrocarbon molecules make the variety of oil and gas products possible, each with specific properties that lend themselves to specific uses.