Multicomponent gas rising through water with dissolution in stratified porous reservoirs - Application to underground storage of H2 and CO2

The exact analytical solutions have been obtained for the problem of the gravity-driven rising of gas stored in a stratified aquifer. The practical objective is to retard gas rising in order to avoid its consecutive losses, which is ensured by low permeable horizontal barriers. The problem of gas rising through water is formulated as the Riemann problem for a system of first-order hyperbolic flow equations coupled with nonlinear algebraic equations describing the dissolution of chemical components in gas and water. The interaction of the forward front of gas with a barrier represents a collision between a shock wave and a medium discontinuity, which produces reverse shock waves and significantly retards gas rising. The method of solution is a combination between the method of characteristics and the technique of geometrical diagrams for coherent waves. The exact analytical solution was constructed for two- and three-component cases. The two-dimensional flow was studied numerically.