Core Flooding of Complex Nanoscale Colloidal Dispersions for Enhanced Oil Recovery by in Situ Formation of Stable Oil-in-Water Pickering Emulsions

Abstract

This study reports a Pickering emulsion flooding system, in which the oil–water interface is structurally stabilized by a complex colloidal layer consisting of silica nanoparticles, dodecyltrimethylammonium bromide (DTAB), and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSS-co-MA). The colloidal layer was generated by adsorption of PSS-co-MA on the silica nanoparticles as a result of the van der Waals attraction and by adsorption of DTAB onto the PSS-co-MA layer as a result of the electrostatic attraction, thus providing the mechanically robust, stable interface. To demonstrate a practical applicability to the enhanced oil recovery, the complex colloidal dispersion fluid was injected into the Berea sandstone for a core flooding experiment. The result revealed that the colloidal dispersion significantly increased the oil recovery by ∼4% compared to the case of flooding water. This means that the emulsion drops in situ produced in the core could readily flow through the rock pores. We attribute...