Resumen publicado por el autor: In this paper, the oil displacement performance of cationic starch was investigated. The results show that cationic starch has good efficiency of oil displacement. Using microscopic electrophoresis apparatus, the effect of cationic starch on zeta potential of crude oil emulsion at different pH values and electrolytical concentrations was studied. The results show that cationic starch can reduce negative charges of oil droplets surface and make the charges reversed. This action will be restrained when acidity or electrolytical concentration increases. Ordinary starch has inefficacy of oil displacement and shows no effect on zeta potential of the oil–water emulsion. The oil displacement mechanism of cationic starch was studied preliminarily from the interactions existing between cationic starch and crude oil

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