Synthesis and characterization of silica-based nanofluids for enhanced oil recovery

The use of nanofluids in enhanced oil recovery processes has gained attention due to the possibility to intensify oil recovery from mature oil fields. When nanofluids are injected into oil wells, different mechanisms are involved such as wettability alteration, reduction of interfacial surface tension, increase in the viscosity of the aqueous solution, and decrease in oil viscosity. Silica nanoparticles are extensively used for nanofluid formulations but there are important obstacles to the use of nanofluids in enhanced oil recovery. Stability is the most evident, in addition to environmental and economic aspects, and the need to design suitable large-scale production processes for nanoparticle synthesis with the required characteristics. Thus, the present study aims to evaluate oil recovery using silica-based nanofluids from various sources (natural rice husk ash, sol-gel synthesis, and commercial nanosilica) under different operational conditions. Silica nanoparticles were characterized by XRF, XRD, TEM, FTIR, specific surface area, and XPS. Nanofluids with different nanoparticles concentration were characterized by their viscosity, surface tension, zeta potential, and stability. Oil recovery from an oil-saturated sand-packed bed increased due to the nanofluid injection after secondary recovery. An additional 5-10% oil recovery is achieved after flooding due to the injection of nanofluids, proving that silica from rice husk ash has comparable efficiency to other synthetic silica nanoparticles that are used in enhanced oil recovery.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).