My recent simulation results http://www.youtube.com/watch?v=oyUNj7HEaro and http://www.youtube.com/watch?v=mEMrxHo_Z7s&feature=relmfu show how CO2 will dissolve in subsurface porous media after injection. The former results due to both density and geothermal gradients where the later is the results for only density difference.
-- Akand Islam