Effect of Hydrophobic Association and Polymer Concentration on Viscoelasticity of Amphiphilic Polymer

The viscoelasticity of the polymer for flooding affects the oil displacement efficiency, and the polymer with viscoelastic properties can increase the oil recovery. In this study, the effect of hydrophobic association on the viscoelasticity of the amphiphilic polymer was investigated by rheometer. The critical association concentration (CAC) of the amphiphilic polymer was determined by the relationship curve between zero shear viscosity and polymer concentration, which is about 800 mg/L. With the increasing of amphiphilic polymer concentration, its viscoelasticity exhibits different characteristics and can be converted from a viscous fluid to an elastomeric fluid. The influence mechanism of hydrophobic association on viscoelasticity of amphiphilic polymer was studied by cohesive energy and scanning electron microscope (SEM). The cohesive energy of the amphiphilic polymer increased from 1.26 × 10−4 Pa to 9.25 × 10−2 Pa when the amphiphilic polymer concentration ranged from 500 to 1200 mg/L. Larger supra-molecular aggregates and stronger network structures can be formed when the amphiphilic polymer concentration is higher than the CAC. The results show that the viscoelasticity of amphiphilic polymer is related to the concentration of amphiphilic polymer and the association strength. This study has certain guiding significance for the application of amphiphilic polymer in oil and gas field development.