$CO_2$ sequestration via pressure driven displacement experiments on fluid-gas plugs in a capillary tube

This talk focuses on experiments conducted to further our understanding on the feasibility of carbon sequestration using a chemical reaction between $CO_2$ gas and aqueous $Ca(OH)_2$ which produces $CaCO_3$ precipitates. Experiments were performed in a capillary tube (dia $\approx$ 800 $\mu$m) by displacing liquid plugs of different volumes containing $Ca(OH)_2$ ($0\leq c \leq20$ mol m$^{-3}$) dissolved in aqueous glycerol solution using $CO_2$ gas at pressures 0.2 psig $\leq$ $P$ $\leq$ 1.0 psig. A CCD camera captured the displaced and displacing fluid interfaces and an in-house MATLAB code was used to measure both the mean $U_m$ and tip $U_t$ velocities. Subsequently, we measure the film thickness using the expression $m=1-U_m/U_t$ where $m$ is a measure of displaced fluid still remaining inside the tube. Surface tension values obtained using an in-house pendant drop tensiometer were used to calculate the capillary number $Ca$. We report the $m$ versus $Ca$ trends observed in our experiments and compare them against immiscible fluid displacement classical results.