Abstract:
CO₂-foam flooding is implemented in order to minimize drawbacks of solely CO₂ flooding by reducing high mobility of CO₂ that could result in impoverishing of ultimate oil recovery. Surfactant solution and CO₂ gas are co-injected simultaneously to generate foam. Foam creates smoother flood front than performing only gas injection. When CO₂-foam contacts with the oil, foam bubbles are weaken and eventually ruptured. Encapsulated CO₂ in those bubbles therefore comes out and be miscible with oil in suitable conditions. This study shows that CO₂-foam flooding yields higher oil recovery factor in the range of 1 to 13% compared to the use of solely CO₂. Performance of CO₂-foam flooding is dependent on many factors. Foam stability is one of the interest parameters but from the simulation results, varying of foam stability slightly affects to the flooding performance. Hence, foam stability might not be one of the first parameters to consider when foam flooding is planned for any field. CO₂-foam application is favorable when reservoir wettability is in the range water-wet condition. For reservoir rocks that possess oil-wet condition, solely CO₂ flooding shows similar or even better result compared to CO₂-foam flooding. Oil composition also affects CO₂-foam. Benefit from CO₂-foam over CO₂ flooding is greater when the hydrocarbon in reservoir contains low intermediate component. The best strategy for CO₂-foam flooding is injecting a whole one slug of CO₂-foam and chasing by water. Dividing foam slug into smaller slugs does not yield any satisfactory results.
