The displacementprocess involves the injection of a solvent such as alcohol, refined hydrocarbons, condensed hydrocarbon gases, liquefied petroleum gases, or carbon dioxide, which can dissolve in the reservior oil. The injected solvent reduced the capillary forces that cause oil retention in the pore spaces of the reservior rocks. In this process, the injected solvent slug is followed by the injection of a liquid or gas to force the solvent-oil mixture out. The miscible displacement process can be subdivided into: 1. The miscible slug process; 2. The enriched gas process; 3. The high-pressure lean gas process; 4. The mutual solvent; 5. Carbon dioxide process.