Influence of alkali-surfactant-polymer flooding on the coalescence and sedimentation of oil/water emulsion in gravity separation

The emulsification and stabilization of the residual chemical within the recovered oil pose difficulties in the primary separation process. This study emphasis on the effectiveness of ASP injection on coalescence and sedimentation of oil and aqueous phases. In addition, the present work is focused at modifying an existing oil/water separation prediction model applicable in the presence of ASP fluids, as the existing model is applicable only to oil/water emulsion. Experimental and empirical techniques have been adopted as a methodology for investigating this work. The modification of the existing model for the prediction of the separation as well as the interaction effect of the parameters were explored. The influence of ASP on separation time in oil-water emulsion were explored in terms of sedimentation and coalescence profiles. Empirical expressions were generated from the batch experiments to find the coalescence and sedimentation constants for various alkali/surfactant/polymer concentrations. The outcomes of the study show that the presence of various ASP concentrations in the oil-water emulsions resulted in a variation in the required separation time. The results also show that alkali in the 500-1500 ppm range has the most significant negative impact on sedimentation. The effect of alkali in reducing sedimentation increases very significantly with surfactant interaction (200-600 ppm). While the polymer in the range of 400-800 ppm and alkali significantly reduced coalescence, as well as the interaction of alkali-surfactant and surfactant-polymer, also contributed significantly to reducing coalescence.