Fluids and Rocks - Introduction to Carbon Capture and Sequestration - page 398

(e)

(f)

Figure 9.3.2 ( Continued )
(d) Simulation results for the constant-CO 2 injection case after 3 days. The fi gures show
in addition to pressure and temperature the CO 2 saturation ( S CO 2 ) and density ( ρ CO 2 )
for the case of the fi xed geothermal gradient boundary condition. The critical pressure
( P c ) and temperature ( T c ) are indicated by the light solid curves on the P and T plots.
(e) In our column, the properties are nearly one-dimensional, which allows us to plot
the average properties as a function of the depth. The data are after 5 days for the
constant-injection case with a fi xed geothermal gradient boundary condition. The
color of the lines represents the value of the variable being plotted against depth, for
visual emphasis. Initial conditions for P and T are shown by the dashed lines. The
liquid-gas phase boundary is shown in the temperature frame by the line labeled T sat .
(f) To see whether during the upwelling the phase behavior of CO 2 changes, the results of
the previous fi gure are plotted in the CO 2 phase diagram. The results are again after
5 days for the constant-injection case with a fi xed geothermal gradient boundary con-
dition. The dashed line shows the initial conditions. The color of the outline of the
symbols represents liquid or supercritical CO 2 saturation, the fi ll color represents gase-
ous CO 2 saturation, and the line color represents aqueous phase saturation with value
ranges shown by the three legends. Note that the abrupt color change that occurs as
the profi le crosses the border between the supercritical and gas regions does not cor-
respond to an abrupt change in properties, merely a change in nomenclature.
Figures reproduced from Oldenburg et al. [9.13] .

cooling can lead to the formation of liquid CO 2 , depending on the ability
of the system to provide heat from the surrounding formation. The
formation of liquid CO 2 during upfl ow could inhibit the upward fl ow, pro-
viding a negative feedback for fast upward leakage as described in
Movies 9.3.1 and 9.3.2 .