Enhanced oil recovery (EOR) is the process of obtaining stranded oil not recovered from an oil reservoir through certain extraction processes. EOR uses methods including thermal recovery, gas injection, chemical injection and low-salinity water flooding. Although these techniques are expensive and not always effective, scientists are particularly interested in EOR's potential to increase domestic oil production.

Also called "tertiary recovery."


|||Thermal recovery uses heat to thin the oil to make it easier to extract and is popular in California. Gas injection, common throughout the United States, can either push out oil or thin it. CO₂ EOR is considered the most promising technique. Chemical injection uses polymers or surfactants to improve oil flow and is not common in U.S. oil production.