Preparation of Temperature-Sensitive SiO2–PSBMA for Reducing the Viscosity of Heavy Oil

Abstract

Viscosity reduction by emulsification is one of the most effective methods for the recovery of heavy oil. Nanoparticles with low toxicity and low cost can stabilize oil-in-water (O/W) Pickering emulsions to reduce the viscosity of heavy oil and thereby have become a new type of emulsifier in recent years. The stimuli-responsive emulsions formed by responsive particles can achieve emulsification and demulsification under external stimuli, providing convenient conditions for heavy oil transportation and recovery, where the temperature response is easier to achieve. In this study, six groups of temperature-sensitive SiO2–PSBMA (PSBMA: polysulfobetaine methacrylate) with different particle sizes were prepared by the reverse atom transfer radical polymerization (RATRP) method. The morphologies of SiO2 particles before and after grafting were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), and the structure of the product was characterized by Fourier transform infrared (FT-IR) spectroscopy, which showed that PSBMA was successfully grafted to SiO2. The grafting ratios (η) of six groups of SiO2–PSBMA measured by thermogravimetric analysis (TGA) were similar (34.50–42.94%). The temperature sensitivity of SiO2–PSBMA was determined by dynamic light scattering (DLS) and the contact angles at different temperatures, which showed that its upper critical solution temperature (UCST) was about 40–50 °C. SiO2–PSBMA was applied to GD2 heavy oil to reduce the viscosity at 60 °C, which showed that the SiO2–PSBMA had a good emulsification effect. With the increase of particle size, the viscosity reduction rate (VRR) showed a trend of first increase and then decrease. The highest VRR was 96.41%, achieved by 227.61 nm SiO2–PSBMA. All of the emulsions stabilized by SiO2–PSBMA were able to demulsify at room temperature. It can be used as an intelligent temperature-responsive viscosity reducer for heavy oil to control emulsions on demand.