Preparation and properties of hyperbranched polymer containing functionalized Nano-SiO2 for low-moderate permeability reservoirs

A novel water-soluble hyperbranched polymer (AA/AM/SMNS) consisting of functionalized Nano-SiO2 as the core was synthesized by free-radical polymerization for low-moderate permeability reservoirs. The AA/AM/SMNS was carefully characterized by spectroscopic and electronic technologies. It was found that the microscopic structures of AA/AM/SMNS was denser and more regular in comparison to the linear polymer HPAM. The hydrodynamic radius of AA/AM/SMNS was 197 nm, less than the HPAM radius of 244 nm with similar molecular weight, so that the AA/AM/SMNS had a good matching relationship with pore throat in midpermeability reservoirs (100-500 mD). Besides, the introduction of Nano-SiO2 endowed the AA/AM/SMNS remarkable thermal stability, shear resistance and viscoelasticity. Based on core flooding experiments, the AA/AM/SMNS could build high resistance factor and residual resistance factor in the corresponding porous medium. Furthermore, the sheared AA/AM/SMNS solution of 1500 mg L-1 performed excellent oil recovery of 15.47% in the 300 mD porous medium, which suggested the hyperbranched polymer based on modified Nano-SiO2 have a valuable prospect for enhancing oil recovery in low-moderate permeability reservoirs.