2D result. In Fig. 8(b), the driving force for forming the large-scale
fingers by nonlinear dynamics seems stronger than that in the 2D
simulation, accordingly more CO2 mass will be transported downward.
In Fig. 8(c), the location of the deepest finger is farther than
the results in Fig. 4(c). Hence, the fingers will be transported faster
with more CO2 moving downward. In Fig. 8(d), the total area of relatively
high concentration is larger than the 2D result, which indicates
that the total inventory is greater than the 2D result.
3.3. Simulations with inclined caprock surfaces
The long-term evolution of solubility trapping in a saline aquifer
with inclined caprock surfaces by 2D simulations is considered,
as shown in Fig. 9. Compared with the 2D simulation with a horizontal
caprock surface shown in Fig. 4, there are some differences,
mainly in the diffusive boundary layer thickness, the position, the
number and the dynamic changes of the fingers. It is observed that
the diffusive boundary layer becomes smoother with the increase
of the inclined angle, indicating that the flow is becoming more
stable with increasing angle. As the angle increases, the number
of fingers generally decreases. Hence, the nonlinear dynamics such
as coalescing and merging of fingers develop very differently in
comparison with the cases with a horizontal caprock surface.
In order to examine the 3D effects of inclined angles on the solubility
trapping, 3D simulations with inclined caprock surfaces
were carried out. Fig. 10 shows the 3D dissolved CO2 contour maps