In a barrel of oil

A single barrel of crude oil, once it has been refined, can yield a large number of useful petroleum products. The ability to obtain products like gasoline, asphalt, and propane from a single raw material is part of what makes refining such a vital process. The refining process separates these different hydrocarbons in a number of ways, one major way being separation by boiling point in a fractional distillation tower.

Products of the Refining Process

When crude oil is processed in a refinery, there is an overall increase in the volume of products. If a single barrel of crude oil, equal to about 159 liters, were refined, the volume of the final products is actually greater than the volume of the initial crude oil. In fact, about 170 liters of refined petroleum products can be obtained from 159 liters of crude oil. There is an increase in volume through the refining process as a result of an effect known as processing gain. Processing gain simply refers to the increase in volume compared to the input that occurs because refined petroleum products have a lower specific gravity than the initial crude oil. This results in the final products "taking up more space" than the initial crude oil.

Figure 1. A pie chart showing the percentage of the final 170 liters of petroleum products obtained from 159 liters of crude oil.

Each product obtained from the refining process is collected in different amounts. In Figure 1, the percentage of the final 170 litres that each product makes up is shown in a pie chart. From the image, it is apparent that vehicle fuels make up a large portion of the final product. In litres, gasoline makes up about 73 liters of the final 170 litres, diesel and heating oil make up about 40 litres, while kerosene-type jet fuels make up about 15.5 litres. Despite the fact that these numbers are comparatively large, it does not mean that the other products are not useful. For example, petrochemical feedstocks make up only 4.2 litres of the final 170 litres; however, they are used to make a variety of products, from pharmaceuticals to plastics. More information about the vast number of products that can be created with petrochemical feedstocks can be found here.

Other products, including still gas, petroleum coke, heavy fuel oil, asphalt, lubricants, aviation gasoline, naphthas, and waxes, make up a fairly small amount of the final product but are widely useful in a number of different applications.