  To simulate CO$_{2,g}$-water flow in tank experiments, subject to viscous,
gravitational and capillary forces as well as the dissolution of this gas
(CO$_{2,aq}$), we constructed a simple pseudo black-oil model. Simple PVT
correlations were used for gas density, viscosity, and solubility as based on
experimental studies and equations of state from the literature. These
solubility calculations assume instantaneous chemical equilibrium. The
applicability of the approach is investigated by modeling the FluidFlower tank
experiment (Nordbotten et al., 2022). The simulation captures the expected
physical phenomena, including capillary filtration, gravitational segregation,
and dissolution fingering. An error in the total mass, due to ignoring
solubility variations with pressure remains acceptable as long as the pressure
variation in the tank is small.
