The volume changes described above (Figures 4−6) are
compared to the initial fluid volume before CO2 injection
(Figure 1). We also compared volume change as the CO2 phase
(s1; Figure 1) dissolves into the brine (s2; Figure 1). As shown
by the reduced area of the displaced brine box between s1 and s2
(Figure 1), dissolution of CO2 into brine reduces the net fluid
volume (compared to the sum of the volumes of brine and CO2 immediately following injection).