The role of water flow and dispersion in the dissolution of CO2 in deep saline aquifers

CO2 dissolution is one of the most important trapping mechanisms and was therefore investigated extensively. The vast majority of studies have neglected the effect of groundwater flow on the dissolution process and convective instability. In this paper, we present measurements obtained in a laboratory aquifer model using a mixture of methanol and ethylene-glycol (MEG) as a CO2 analog while varying the water horizontal flow rate. Gravitational instability was quantified by analyzing the fingers' dynamics. It was found that water flow reduces the number of fingers, suppresses their wavenumber, limits the fingers' propagation and decreases the interface tortuosity. At high flow rates, no convective regime exists and dissolution rate decreases. (C) 2017 The Authors. Published by Elsevier Ltd.