CO2 storage in deep saline aquifers is a promising technique for carbon neutrality. Accelerating the dissolution rate of dissolution trapping is key to improving storage efficiency and providing long-term storage security. In this study, density-driven convection processes were conducted using magnetic resonance imaging (MRI) with two analog fluid pairs as equivalents of the CO2-brine fluid system. Superhydrophilic SiO2 NPs with different mass fractions (0 wt%, 0.1 wt%, and 1 wt%) were added to the dense fluid to investigate the optimum mixing ratio. The basic fluid interface instability is identified. The addition of nanoparticles shortens the onset time of instability and increases the finger numbers in each axial section. It shows that dense fluid with NPs leads to more stable interface behavior. Furthermore, experimental results confirm that a reduction in surface tension between NPs and CO2 would enhance fluid miscibility and mass transfer during convection. This study can expand the perspective on accelerated dissolution rates and CCS security in the substance.
Keywords CO2 storage, dissolution trapping, nanoparticles, interfacial instability, CCS security