title: Aquifer-on-a-chip: understanding pore-scale salt precipitation dynamics during CO2 sequestration.
abstract: In this study, we develop a lab-on-a-chip approach to study pore-scale salt precipitation dynamics during CO2 sequestration in saline aquifers-a challenge with this carbon management strategy. Three distinct phases-CO2 (gas), brine (liquid), and salt (solid)-are tracked through microfluidic networks matched to the native geological formations. The resulting salt formation dynamics indicate porosity decreases of ~20% in keeping with large scale core studies. At the network scale, the salt precipitation front moves at a constant velocity, ~2% that of the superficial CO2 velocity in this case. At the pore-scale, we observe two dominant types of salt formation: (1) large bulk crystals, on the order of the pore size (20-50 μm), forming early within trapped brine phases; and (2) polycrystalline aggregated structures, ranging over broad length scales, forming late in the evaporation process and collecting/projecting from the CO2-brine interface. Together, these two salt formation mechanisms show particular propensity for pore blockage and reduced carbon storage capacity.
authors.affiliation: Institute for Sustainable Energy, and Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G8.
authors.forename: Myeongsub
authors.initials: M
authors.lastname: Kim
authors.forename: Andrew
authors.initials: A
authors.lastname: Sell
authors.forename: David
authors.initials: D
authors.lastname: Sinton