Ultrasound assisted waterflooding: an experimental study of the mechanisms

Waterflooding fails to produce more oil due to high viscosity of oil and/or high interfacial tension. Additional oil may be recovered by application of EOR methods such as: Chemicals, miscible flooding and thermal methods. Another alternative and yet unconventional EOR method is application of ultrasound waves to waterflooding as a method to improve the recovery of oil. However, despite number of researches on the applications of ultrasonic waves, the influencing mechanisms are not fully comprehended. The aim of this research is to experimentally investigate the effects of ultrasonic waves on recovery of waterflooding and to discuss the mechanisms involved in this process. Series of straight and ultrasonic stimulated waterflooding experiments were conducted on a long unconsolidated sand pack and the oil recovery was measured at the end of the experiments. Kerosene, vaseline and engine oil were used as non wet phase in the system. In addition to that, a series of supplementary experiments were conducted using ultrasonic bath in order to enhance the understanding about contributing mechanisms. 2-16% increase in the recovery of waterflooding was observed as a result of ultrasonic stimulation. Emulsification and viscosity reduction were identified as main mechanisms affecting improvement of oil recovery by waterflooding. . The ultrasonic recovery was lower for higher viscosity of oils. The findings of this research are expected to increase the insight about involving mechanisms which lead to improving the recovery of oil as a result of application of ultrasound waves.