Petroleum refineries process crude oil into many different petroleum products. The physical characteristics of crude oil determine how the refineries turn it into the highest value products.
Not all crude oil is the same
The physical characteristics of crude oil determine how refineries process it. In simple terms, crude oils are classified by density (API gravity) and sulfur content. Less dense (lighter) crude oils (with higher API gravity) generally have a larger share of light hydrocarbons. Refineries can produce high-value products such as gasoline, diesel fuel, and jet fuel from light crude oil with simple distillation. When refineries use simple distillation on denser (heavier) crude oils (with lower API gravity), they produce low-value products. Heavy crude oils require additional, more expensive processing to produce high-value products. Some crude oils also have a high sulfur content, which is an undesirable characteristic in both processing and product quality.
Refineries use more than just crude oil
In addition to crude oil, refineries and blending facilities add other oils and liquids during processing to produce the finished products that are sold to consumers. These other oils and liquids include liquids that condense in natural gas wells (called lease condensates); natural gas plant liquids from natural gas processing; liquefied gases from the refinery itself; and unfinished oils that are produced by partially refining crude oil, such as naphthas and lighter oils, kerosene and light gas oils, heavy gas oils, and residuum. Residuum is a residue from crude oil that remains after distilling off all but the heaviest components.
Gasoline accounts for the largest share of total petroleum products produced each year in U.S. petroleum refineries.
Refineries and blending facilities combine various gasoline blending components and fuel ethanol to produce the finished motor gasoline that is sold for use in the United States. They may also add biomass-based diesel fuel to petroleum fuels to make blends of biomass-based diesel, jet fuel, and heating oil.
Refining output is larger than input
The total volume of products refineries produce (output) is greater than the volume of crude oil that refineries process (input) because most of the products they make have a lower density than the crude oil they process. This increase in volume is called processing gain. The average processing gain at U.S. refineries was about 6.2% in 2019. In 2019, U.S. refineries produced an average of about 45 gallons of refined products for every 42-gallon barrel of crude oil they refined.
|Finished motor gasoline||19.40|
|Distillate fuel oil||12.47|
|Kerosene-type jet fuel||4.41|
|Hydrocarbon gas liquids||1.47|
|Residual fuel oil||0.88|
|Asphalt and road oil||0.80|
|Naptha for feedstocks||0.46|
|Other oils for feedstocks||0.25|
|Finished aviation gasoline||0.04|
|Source: U.S. Energy Information Administration, Petroleum Supply Annual, August 2020|
Last updated: September 10, 2020