Abstract: When using chemical agents especially surfactants to displace oil，the inorganic ions，which are contained in reservoir formation water，can have influence on emulsification and other properties of surfactant.Oil-in-water emulsion was prepared by using dehydrated crude oil and 0.4% （mass fraction） sodium dodecyl benzene sulfonate （SDBS）.Thirteen inorganic salts with different concentrations were added to the SDBS emulsion，so as to investigate the influence of those inorganic salts on emulsion stability and phase inversion.Experimental results showed that Na and K salts both had optimum mass concentrations；emulsion stability was enhanced at those two optimum mass concentrations，but they did not cause emulsion phase inversion.Bivalent and trivalent inorganic salts had adverse influence on emulsion stability， the ability of these inorganic salts that impel emulsion phase inversion to happen was in sequence of AlCl₃＞FeCl₃＞BaCl₂＞SrCl₂＞CaCl₂＞MgCl₂.Alkalescent sodium salts had synergistic effect with SDBS and had favorable influence on emulsion stability when its mass concentration was in optimum salt  mass concentration.

Key words: inorganic salt, sodium dodecyl benzene sulfonate, emulsion, stability, phase inversion