Microemulsion flow in porous medium for enhanced oil recovery

• Lower mobility ratios were acquired with the injection of microemulsion.
• The volume of oil displaced by the microemulsion was much higher.
• An increase in efficiency of about 21.5% was observed with the use of microemulsion.

Injection of microemulsion is a chemical technique of enhanced petroleum recovery. With the implementation of this technique, oil recovery is enhanced by increasing the viscosity of the microemulsion systems, and reducing the interfacial tension between oil and water in a porous medium. In this work, injection assays have been carried out with fluids comprising microemulsion-based commercial anionic surfactants, oil from the Quiambina Field (mature field in the Brazilian State of Bahia) and brine (2% KCl). The experiments basically consisted of the injection of fluids into cylindrical plug samples from the Botucatu formation by means of conventional (injection of water or brine) and enhanced (injection of microemulsion) recovery techniques. During water and microemulsion flooding, samples were collected as a function of time, after which the volume of oil recovered was obtained. Parameters like mobility ratio, volume of displaceable oil, volume of displaced oil and displacement efficiency have been obtained as results. It was verified that lower mobility ratios were acquired with the injection of microemulsion than with injection of water, thereby favoring oil recovery. The volume of oil displaced by the microemulsion corresponded to 75% of the total displaceable oil, which is a much higher yield than that observed in conventional recovery procedures. The results showed that, when microemulsion flooding is applied, the displacement efficiency is 21.5%, whereas with the conventional method the efficiency is 41%. It could be concluded that the use of microemulsion in enhanced oil recovery is efficient to provide higher levels of extraction due to the higher viscosity of the microemulsion and to the decrease in the interfacial tension between the fluids in the porous medium.