淀粉/SiO2核壳纳米复合增注剂的制备与性能OA

To address the challenges of high injection pressure and low oil recovery during water flooding in medium-low permeability reservoirs,a novel starch/SiO2 core-shell nanocomposite injection enhancer(SO-K-Si)with a"rigid nano-core and hydrophobically modified shell"(core-shell)structure was developed.The material was synthesized from corn starch and industrial nano-SiO2 through a three-step process involving oxidation,hydrophobic modification,and in situ composite formation.The optimal formulation of SO-K-Si was determined by laser particle size analysis and surface tension measurements,with a mass ratio of oxidized starch,nano-SiO2(10 nm),and γ-methacryloxypropyl-trimethoxysilane of 8∶4∶3.The surface/interfacial tension,wettability regulation,core permeability,and injection pressure of SO-K-Si fluid were evaluated via surface tension testing,interfacial tension measurement,contact angle measurement,and core flooding experiments.Comparative studies were conducted using fluids of nonionic surfactant octylphenol polyethoxyether-10,hydrolyzed polyacrylamide,and a commercial nanocomposite injection enhancer.Experimental results indicate that SO-K-Si fluid achieves an ultra-low interfacial tension of 10-2 mN/m at low concentrations(0.05%-0.10%(w)).It reduces the core surface contact angle from 125° to 33°,demonstrating a strong wettability reversal effect.In core flooding tests,the fluid increases core permeability by approximately 41%and reduces injection pressure by 36.8%,showing significantly better overall performance than the other three fluids.This work successfully develops an efficient,low-cost nanomaterial for injection enhancement.Moreover,a multi-scale mechanistic analysis covering"structure-interface-flow"provides important material foundation and theoretical support for pressure reduction and injection enhancement technologies in medium-low permeability reservoirs.