The Effect of Surface Treated Nanoparticles on Single and Multi-Phase Flow in Porous Media

Surface treated nanoparticles have been suggested to be an additive to CO2 storage scenarios. This is because 1) the nanoparticles have been shown to freely transport through permeable media, and 2) the nanoparticles can stabilize a CO2 in water foam by adhering to the surface of CO2 bubbles/droplets preventing their coalescence. In terms of storage, The formation of CO2 foam will limit the CO2 mobility which can potentially help limit the CO2 leakage. Here, we will show how nanoparticles in porous media can have many interesting properties in single and multi-phase flow. For multi-phase CO2, we have performed experiments where high pressure liquid CO2 displaces brine and vice versa with and without nanoparticles in the brine. We measure the displacement pattern and in-situ CO2 saturation using CT scanning and measure the pressure drop using pressure transducers. We find that the flow is less preferential and the pressure drop is greater than when nanoparticles are present. This suggest the formation of in-situ foam/emulsion. We also show that on a brine chase, the residual saturation of CO2 is greater in the presence of nanoparticles. In terms of nanoparticle transport, it is observed that nanoparticles accumulate at the front of a brine/octane displacement. We hypothesize that this occurs due to the nanoparticles being size excluded from portions of the pore-space. To determine if this occurs in single phase flow, we have also performed experiments single-phase flow with the nanoparticles and tracer. We find that the nanoparticles arrive roughly 5% faster than the tracer. This also has implications for the positioning of nanoparticles in the pore space and how this can change the effective viscosity of the nanoparticle suspension.