Study of Time-Varying Laws of Stability and Wettability of SiO2-H2O Nanofluids with Different Particle Sizes

It has been proven that SiO2-H2O nanofluidshave great application potential for water injection in coal seams.To explore the influences of the particle size on the stability andwettability of SiO2-H2O nanofluids, sedimentationobservation of nanoparticles (NPs), viscosity tests, pH tests, surfacetension tests, and contact angle tests were performed for SiO2-H2O nanofluids with different particlesizes. The research shows that the larger the particle size of SiO2 NPs, the more obvious the aggregation and sedimentation ofNPs. The smaller the particle size of SiO2 NPs is, thelower the surface tension and contact angle of the SiO2-H2O nanofluids. As time goes on, SiO2-H2O nanofluids successively show time-varyingcharacteristics in the low stability stage, moderate stability stage,and high stability stage. Therein, the low stability stage is theoptimal period for enhancing the water injection in coal seams bynanofluids. The research provides theoretical support for using SiO2-H2O nanofluids to enhance water injectionin coal seams.

Automated summary

SiO2-H2O nanofluids have great potential for water injection in coal seams. The particle size of SiO2 NPs affects the stability and wettability of the nanofluids. Larger particle size leads to more aggregation and sedimentation, while smaller particle size results in lower surface tension and contact angle. The nanofluids show time-varying characteristics, with the low stability stage being the optimal period for enhancing water injection. This research provides theoretical support for using SiO2-H2O nanofluids in coal seam water injection.