Nanoscale Polyacrylamide Copolymer/Silica Hydrogel Microspheres with High Compressive Strength and Satisfactory Dispersion Stability for Efficient Profile Control and Plugging

Polyacrylamide (PAM)-based microspheres are commonly used as water plugging and profile control agents, but the poor mechanical strength and few studies on the dispersion stability, both of which are closely related to the profile control performance, limit the application of microspheres. Herein, we synthesize nanoscale PAM-based copolymer hydrogel microspheres with an inverse microemulsion copolymerization of acrylamide (AM) and 2-methyl-2-acrylic amide propyl sulfonic acid (AMPS) in the presence of vinyl-functionalized silica nanoparticles (VSNPs). The results show that a small amount of VSNPs (1.0 wt %) increases the compressive strength of the hydrogel by 0.6 times. The swollen nanoscale PAM/silica hydrogel microspheres show good dispersion stability. VSNPs significantly improve the elasticity of the hydrogel microspheres, and their dispersion stability under high temperature and high-salinity conditions. The simulation evaluation of core plugging suggests that the plugging rate of PAM-based polymer/silica hybrid microspheres with addition of 0.7 wt % VSNPs increases from 80% to 92% compared to neat polymer microspheres. This work provides a novel design of nanoscale cross-linked microspheres for deep profile control in different geological environments.