LAUSR

Abstract In order to overcome the inherent defects of traditional polymer microspheres as plugging agent used in oilfields, including weak mechanical properties, low dispersity in water and poor adaptability to harsh conditions, an organo-modified montmorillonite (O-MMT) was incorporated to form an exfoliated structure in acrylamide/sodium 4-styrenesulfonate/2-acrylamido-2-methyl propane sulfonic acid (AM-SSS-AMPS) terpolymer matrix via in-situ polymerization. Such exfoliated structure not only exhibited a considerable enhancement in the comprehensive properties of nanocomposites, such as viscoelasticity, heat and shear-resistance, but also improved nanomechanical properties of microspheres. The results of nanomechanical properties showed that the energy dissipation and adhesion of nanocomposite with 3.0 wt% O-MMT were decreased to only 1.9% and 4.7% of those of the original terpolymer, respectively, implying the reduction in the agglomeration and energy consumption of microspheres in aqueous suspension. Rheology test demonstrated that the suspension (5.0 wt%) of nanocomposite microsphere with 2.0-3.0 wt% O-MMT behaved as pseudoplastic fluid, Newtonian fluid and dilatant fluid in turn at the shear rate from 10 s-1 to 1000 s-1, which indicated a better arrangement of microspheres in suspension under shear stress. G′ and G′′ of the suspension of nanocomposite microspheres with 3.0 wt% O-MMT were 696.6 times and 84.4 times higher than those of the terpolymer suspension, respectively, and the corresponding viscosity was 10.4 times higher at 90 ℃. These superior properties of nanocomposite microspheres will meet the tough requirements of oilfield development.