Enhancing the Security of Geologic Carbon Storage Using Coated Silicate Nanoparticles

The large-scale deployment of geologic carbon storage has been hindered by several factors including the risk of CO2 leakage. Here we report on the development of functionalized reactive nanoparticles that could be co-injected with the CO2 to seal flow pathways that might lead to large scale leakage. The nanoparticles, consisting of a mineral silicate core coated with a temperature-sensitive polydopamine shell, are unreactive at high temperatures near the injection site but become reactive at the lower temperatures that would prevail near leakage zones. Once the core material comes in contact with aqueous CO2, it will react to form calcium or magnesium carbonate precipitates that reduce the permeability of the fracture or flow path. Functionalized nanoparticles containing calcium silicate (CaSiO3) cores were synthesized and coated before being injected into sand columns. Above the critical temperature for the coatings, the permeability drops were modest but below the critical temperature, much more significant drops were observed. SEM-EDS and synchrotron XRD and XRF were used to characterize the morphology and location of the precipitates to demonstrate that they could would effectively block fluid flow even at relatively low nanoparticle concentrations far from the injection well. A model of nanoparticle transport was developed to provide insight into the effect of nanoparticle size, coating properties, and concentrations in various representative formations.