Enhanced Oil Recovery (EOR) Techniques is used for increasing the amount of oil that is extracted from an oil field. It is also called as improved oil recovery or tertiary recovery. This extraction is achieved by either gas injection, thermal recovery or chemical injection. Gas injection injects gas such as carbon dioxide, natural gas or nitrogen into the reservoir and pushes additional oil to a production wellbore, and dissolves in the oil to lower its viscosity and improves the flow rate of the oil. Thermal recovery uses heat to improve flow rates. In chemical injection, polymers are injected to increase the effectiveness of water floods.