Effect of inorganic particles on the rheological properties of nano-SiO2 grafted modified polymers

Abstract

Polymer flooding technology has become the most widely utilized chemical flooding technology in the world. The polymer structure gradually grows from linear to branched and hyperbranched as reservoir variability increases and polymer flooding technology advances. In this study, the nano-SiO2 was first controllably modified, and subsequently, a series of nano-SiO2 grafted modified polymers (MNSP) were synthesized using homogeneous aqueous solution polymerization with modified nano-SiO2 and another functional monomer. The rheological properties of MNSP were analyzed by using the MCR 301 rheometer; then, the mechanism of the influence of the concentration and the modification degree of nano-SiO2 on the rheological properties of MNSP was explored from the microscopic standpoint. The results demonstrate that at a salinity of 3 × 104 mg/L and temperature of 85 °C, the viscosity of the MNSP polymer is superior to that of the standard amphiphilic polymer APC16 whose synthesized monomers do not include nano-SiO2. When the concentration and the modification degree of nano-SiO2 were increased, the solution viscosity first increased and then decreased, and this is mostly due to the addition of inorganic nanoparticles, which stimulates the creation of a three-dimensional network structure and improves the solution characteristics of MNSP. However, too much modified SiO2 addition will interfere with polymerization between various monomers. The modification degree of the nano-SiO2 mostly influences the density of the polymer-formed network structure, the active sites on the modified nano-SiO2 surface rise as the degree of modification increases, as does spatial site resistance, resulting in inferior polymer characteristics. The findings of the experiments reveal fresh ideas for inorganic particles compounding organic polymers and expand the use area of polymers in the oilfield.