Viscoelastic Properties of Oil-in-Water (o/w) Pickering Emulsion Stabilized by Surfactant–Polymer and Nanoparticle–Surfactant–Polymer Systems

Abstract

Oil in water (o/w) Pickering emulsion stabilized by a nanoparticle–surfactant–polymer system shows better thermal stability than the one stabilized by a surfactant–polymer system. The knowledge of the viscoelastic properties of these emulsion systems is important for their successful application for high pressure and high temperature conditions related to enhanced oil recovery (EOR). In this work, the viscoelastic behavior (G′ and G″) of the Pickering emulsion stabilized by a nanoparticle–surfactant–polymer system has been investigated as a function of pressure (0.1–30 MPa) and temperature (298–371 K) and compared with conventional emulsion stabilized by a surfactant–polymer system. An oilfield polymer polyacrylamide (PAM) along with nanoparticles (SiO2 and clay) and conventional surfactants are used for the formulation of Pickering o/w emulsion systems. Both the emulsion systems showed liquid-like behavior at 0.1 MPa with G″ dominance over the complete range of strain amplitude. It is observed that Pickering emulsions are found to be more stable at high pressure conditions as the pressure effect did not show any significant influence on the viscoelastic properties. Pickering emulsions behave like viscoelastic fluid at all pressure conditions as compared to the surfactant–polymer stabilized emulsion, wherein the storage modulus has shown rapid increase with increase in pressure from 0.1 to 30 MPa. In addition, Pickering emulsions showed better flowability by showing stable G″ values for varying conditions of temperature as compared to the surfactant–polymer stabilized emulsion. The stable viscoelastic response for Pickering emulsion is beneficial for their implementation at complex reservoir conditions.