A Systematic Computational Study of Oil Displacement Processes in Terrigenous and Cavernous-Fractured Porous Media Using Surfactant Solutions

This paper presents the results of a numerical simulation of oil displacement from models of terrigenous and cavernous-fractured media using solutions of the anionic surfactant (sodium laureth sulfate). The surfactant concentration was varied from 0 to 0.1 wt.%. The simulations employed a mathematical model for the flow of immiscible liquids based on the VOF method. The model incorporated experimentally measured interfacial tension coefficients and wettability parameters for the surfactant solutions. The results demonstrate that increasing the surfactant concentration enhances the oil displacement coefficient: by 15% for the terrigenous model and by 19% for the cavernous-fractured model compared to water flooding (at 0 wt.% surfactant), achieving a maximum at a concentration of 0.1 wt.%. The influence of potential mechanisms leading to the improved oil displacement coefficient during surfactant solution injection was investigated. It was established that at a fixed displacement rate, the addition of the surfactant causes a local increase in the generalized capillary number by a factor of approximately 3.7. This is identified as the primary mechanism for the observed enhancement of the oil displacement coefficient in this case. The data obtained in this study can be used for further improvement of surfactant flooding technologies for enhanced oil recovery.