Foam injection is used in oil reservoir to reduce surface tension between gas and oil and also between water and oil. Foam is an intermediate state between gas and liquid that can reduce surface tension and thus increase oil production. This method is usually used for reservoirs with heterogeneities in reservoir rock properties or fractured reservoirs, where gas injection alone is problematic. Foam injection can be done with the aim of delivering the surfactant to the oil inside the matrix and reducing the surface tension between the gas and oil. In this case, with the reduction of capillary forces, the existing balance between capillary and gravity forces will be more in favor of gravity forces, oil recovery will be increased. This method reduces surface tension on the liquid surface and improves gas flow in non-homogeneous areas in an oil reservoir. Foam injection causes uniform displacement of the fluids in the reservoir and prevents the occurrence of fingering.