Characterization of Surfactant Adsorption Profile in Carbonates Under Severe Reservoir Conditions With Geochemical Modeling Approach

Chemical flooding has gained ample popularity as an effective technique to increase oil displacement and sweep efficiencies. However, very limited numerical applications of chemical flooding (surfactant and polymer) in carbonates are reported in the literature. Therefore, a geochemical-based surface complexation model is developed to characterize the adsorption profile of surfactants for the first time across the length of a core/reservoir. The proposed model is validated with various zeta-potential measurements and also with a recently conducted chemical flooding study. Additionally, sensitivity analysis of various parameters is performed, and it is found that surfactant effluent concentration decreases with the increase in flood temperature. It is observed that salinity reduction decreases the surfactant adsorption, increases the ionic repulsion amid the rock surface charge and the chemical species polarity. Similarly, when the concentration of surfactant is increased, the adsorption of surfactant concentration increases. However, the increase in surfactant adsorption is insignificant. The effect of sulfate spiking in chemical flooding is also investigated and it is found that an increase in sulfate concentration reduces the adsorption of surfactant across the reservoir. Moreover, the lowermost surfactant adsorption level is achieved through the injection of diluted water (<0.1 mg/g).