The effects of surfactant concentration and slug ratios on oil recovery by surfactant-alternate-gas flooding

Abstract

Tertiary (enhanced) oil recovery is that additional recovery over and greater than the amount recovered by primary and secondary recovery methods [1]. In other words, enhance oil recovery (EOR) are the actions taken in order to increase the cumulative oil production after depletion of natural driving forces and water flooding techniques are no more efficient to be carried out. The Air Injection Processes (AIP), one of the gas flooding techniques and is well established in the oil and gas industry due to its consistency in producing unrecoverable oil. For instance, Water-Alternate-Gas (WAG) technique usually carried out proves to give better recovery. Water slug used in this method stabilizes the gas front and increase sweeping efficiency. Problems that usually occur during displacement are viscous fingering phenomenon and gravity segregation especially when it sweeps vertically. To give better control of viscous fingering, surfactant is added to the water to reduce its interfacial tension. This will gives rise to another variation to WAG which is Surfactant-Alternate-Gas flooding [2][3].