Experimental Evaluation of Oil Recovery Mechanisms Using a Variety ofSurface-Modified Silica Nanoparticles in the Injection Water

摘要

Lack of relevant screening methods of oil recovery techniques for water flood with added nanoparticles ina given reservoir are hindering its implementation for enhanced oil recovery (EOR) purposes. Moreover,the understanding of the underlying mechanisms of oil increased by nanoparticles must be improved. In this work, we screened twenty-three different types of silica nanoparticles as additives to injectionwater for oil recovery applications. The nanoparticles were surface functionalised to remain stable in theinjection water and be active at the surface. The hypothesis is that the particles will improve the microscopicoil recovery efficiency of water flood in an oil reservoir. The concentrated solution of nanoparticles wereprepared to 0.1 wt % concentration in synthetic North Sea water. Crude oil was obtained from a fieldin the North Sea. The following investigations were carried out to quickly verify the performance ofnanoparticle oil recovery: 1) secondary injection through a visual glass micromodel. 2) For the prominentsilica nanoparticles, we evaluated oil recovery by conducting secondary core flooding experiments in water-wet Berea sandstone rocks; and 3) the displacement mechanisms of nanoparticles were investigated byinterfacial tension measurements between nanofluids and crude oil; Amott-wettability test; and by analyzingdifferential pressure across the core. Experimental results from secondary floods showed that modified silica nanoparticles can boost oilrecovery. The core flood recoveries ranged from 45.7% to 54.5% of original oil in place (OOIP) comparedto 39.7% of reference water flood. Displacement studies revealed that, oil recovery was obtained froma contribution of interfacial tension reduction, wettability alteration, and log jamming effect due to poreblockage. This work suggests a procedure for screening nanoparticles for EOR applications while providinginsights into the role of the modified-silica nanoparticles for recovery of oil.