Figure 4.

CO₂ sinking mechanism. The numerically computed sinking profile of CO₂, represented as the area with CO₂ saturation S _c > 1, is a consequence of the interplay between gravity and viscous forces as represented by the values of the gravity number N. Cold CO₂ injection does not increase CO₂ buoyant potential because thermal equilibrium is reached within a small region from the wellbore where viscous forces dominate over gravity forces. At the far field, CO₂ is in thermal equilibrium with the reservoir, becoming denser than water, and since gravity forces are greater than viscous ones, CO₂ has the tendency to sink.