Emulsion Formation and Stability Evaluation in the Presence of Different Ions during Surfactant Flooding

Summary The existence of different ions in the formation water and aqueous phase, which injected into the oil reservoir has received attention. Formation and the stability of water-in-oil emulsion (w/o) are influenced by the phenomena that occur are at the porous media. As a novelty in this study, the absence of natural surfactant (asphaltene) was investigated, and also the effect of Alpha Olefin Sulfonate (AOS) which is an anionic surfactant on forming emulsions in the presence of salts like magnesium chloride, calcium chloride, and sodium chloride was investigated. analyzing the microscopic view of the formed emulsion is the basis of this study, and also centrifuge tests were conducted to determine the stability from another aspect at the ambient pressure and temperature. Various concertation of surfactant and ions have been studied, and the optimum concentration for each mixture has been attained. The result illustrates that at low salinities (i.e. up to 10,000 ppm) the stability of emulsions increases and decreases. The comparison between divalent and monovalent ions shows higher stability for emulsions which includes divalent ions, especially for magnesium ion. At higher salinities, the emulsion stability dramatically decreases, and water droplets are not able to disperse into the oil phase properly.