Second Recovery and Enhanced Oil Recovery

All methods utilized to improve on primary recovery through natural depletion, which uses only the difference in pressure between the oil or gas reservoir and the production wells. These methods include artificial lift, one type of which is gas lift (injecting gas micro-bubbles into the production well to reduce the density of the fluid in the fluid column); injecting gas or water into the lower section of the deposit via injection wells; injecting steam to reduce the oil’s viscosity and increase its mobility; chemical flooding (injecting surfactants); and injecting carbon dioxide CO2 (method also used to store CO2).