The Refining Process
Refining Crude Oil – Inputs & Outputs
Refineries process crude oil into different petroleum products, such as gasoline, jet fuel, asphalt, and others. The most basic refining process separates crude oil into its various components. Crude oil is heated and put into a distillation tower (a still) where different hydrocarbon components are boiled off and recovered as they condense at different temperatures.
Not All Crude Oil Is Created Equal
The physical characteristics of crude oils can be different. In simple terms, crude oils are classified by their density and sulfur content. Less dense (or "lighter") crudes generally have a higher share of light hydrocarbons — higher-value products such as gasoline, jet fuel, and diesel — that can be recovered with simple distillation. The denser ("heavier") crude oils produce a greater share of lower-valued products with simple distillation and require additional processing to produce the desired range of products. Some crude oils also have a higher sulfur content, an undesirable characteristic with respect to both processing and product quality.
Refineries Use More Than Just Crude Oil
In addition to crude oil, refineries and blending facilities use and add other oils and liquids to produce finished products for sale to consumers. These include liquids that condense in gas wells (called "lease condensates"), natural gas plant liquids from natural gas processing, and unfinished oils that are produced by partial refining of crude oil (such as naphthas and lighter oils, kerosene and light gas oils, heavy gas oils, and residuum — residue from crude oil after distilling off all but the heaviest components).
Blending facilities add oxygenates (such as ethanol) and various "blending components" to produce finished motor gasoline. Blenders also add relatively small, but increasing, amounts of "biodiesel" (made from vegetable oils or animal fats) to diesel fuel and heating oil.
Output Is Larger than Input
Petroleum refining results in output greater than the input because of changes in the overall density of the refined products relative to that of the input oils. These changes result in an increase in the volume of products produced that is called processing gain. U.S. processing gain averaged about 6.2% from 1996 through 2010.
In 2010, about 44.98 gallons of refined products were produced for every 42 gallon barrel of oil input into U.S. refineries.
Petroleum Products Produced from