Gravity currents of carbon dioxide with residual gas trapping in a two-layered porous medium

In the geological sequestration of carbon dioxide (CO 2 ), residual gas trapping plays an important role in immobilizing CO 2 . In this study, we investigate the propagation of gravity currents with residual gas trapping in a two-layered porous medium. We first formulate a model for a constant-flux release of a relatively less dense fluid (CO 2 ) from a point source into a porous medium bounded above by a horizontal less-permeable seal. After a constant-flux release ceases, a fraction of the released fluid remains within the porous spaces at the trailing edge because of the capillary forces. This capillary retention is formulated in a model of gravity currents of a finite-volume release in the two-layered medium. In the latter model, the plume shape at the end of the constant-flux release is used as an initial profile. Using these models sequentially, the propagation of both cross-sectional and axisymmetric currents is quantitatively examined.