Alkaline Surfactant (AS) flooding is an enhanced oil recovery (EOR) method to mobilize residual oil. Deatailed understanding of transport during these recovery mechanisms requires detailed pore-scale studies. This point leads to the utilization of X-ray imaging for its application in pore-scale characterization. Synchrotron-based X-ray imaging is an advanced technique that is capable of capturing the dynamics of pore fluids at the microscopic scale. The aim of this project is to investigate the pore-scale flow of AS flooding at two different salinities in carbonate rocks using real time 3D images collected by synchrotron-based X-ray imaging. The morphologies of the non-wetting phase are first computed, and oil recovery in the two scenarios is estimated. In addition, the wetting states of the two conditions are assessed by contact angle measurements. It was observed that optimum, or Winsor type III mobilized more oil, since it yielded a higher recovery value, as compared to under-optimum or Winsor type II-. Alkaline surfactant at optimal salinity was marked as an ideal condition that effectively reduces interfacial tension (IFT) to mobilize residual oil. This study provides insights in the pore-scale flow mechanisms that occur during AS flooding, which are important for understanding the basic EOR mechanism of this particular flood.

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