Enhanced oil recovery

Patent Pending Enhanced Oil Recovery (abbreviated EOR) is a generic term for techniques for increasing the amount of crude oil that can be extracted from an oil field. Enhanced oil recovery is also called improved oil recovery or tertiary recovery (as opposed to primary and secondary recovery). Sometimes the term quaternary recovery is used to refer to more advanced, speculative, EOR techniques.[1][2][3][4] Using EOR, 30 to 60 percent or more of the reservoir's original oil can be extracted,[5] compared with 20 to 40 percent using primary and secondary recovery.