Crude oil development and production in oil reservoirs can include up to three distinct phases: primary, secondary and tertiary (or enhanced) recovery. During primary recovery, the natural pressure of the reservoir or gravity is what drives oil into the wellbore, combined with artificial lift techniques (such as pumps) which bring the oil to the surface. But only about 10 percent of a reservoir’s original oil in place is typically produced during primary recovery. Secondary recovery techniques add to the field’s productive life generally by injecting water or gas to displace oil and drive it to a production wellbore, resulting in the recovery of 20 to 40 percent of the original oil in place. However, with much of the easy-to-produce oil already recovered from many oil fields, producers have attempted several tertiary, or enhanced oil recovery (EOR) techniques that offer prospects for ultimately producing 30 to 60 percent, or more, of the reservoir’s original oil in place.