Design of Alkaline/Surfactant/Polymer (ASP) Slug and its use in Enhanced Oil Recovery

Abstract

Studies have been done to design an optimum composition of alkali/surfactant/polymer (ASP) slug and its application in flooding to increase the additional recovery of oil. A very low concentration of alkali and surfactant is used to achieve ultra-low interfacial tension between the trapped oil and the injection water, and polymer is used to increase the viscosity of the injection water for mobility control. Based on the experimental results of physico-chemical properties of polymer, surfactant, and alkali and their mutual interaction in solution, an ASP slug of composition SDS: 0.1 wt%, SDBS: 0.075 wt%, polyacrylamide: 2,000 ppm, and NaOH: 0.7 wt% has been recommended for flooding. Two sets of core-flooding experiments have been conducted using the designed ASP slug in a tri-axial core holder to measure the additional recovery of oil. The average additional oil recovery over conventional water flooding was found to be more than 20% of the original oil in place (OOIP).