PNNL-13501 - Pacific Northwest National Laboratory

injection of an immiscible gas phase into confined formations
(representing deep saline aquifers and reservoirs), its
axisymmetric flow around the injector, and eventual
buoyancy-driven transport with simultaneous dissolution
and mineral trapping. In addition, a numerical model
(STOMP-CO2) has been developed by adding additional
phase behavior algorithms to our STOMP simulator.
Results and Accomplishments
Simple and easy-to-use modeling tools would be valuable
for assessing the performance of a deep-well operation
during and after injection. We have completed a semianalytical
model (PNLCARB) and a numerical model
(STOMP-CO2) by adding additional phase behavior
algorithms to the STOMP simulator, to model
1) multiphase, radial injection of CO2 and the growth of
its area of review around the injector, 2) buoyancy-driven
migration of CO2 toward the top confining layer, and
3) dissolution of CO2 during injection and vertical
migration, and the resulting aqueous speciation of carbon.
The models effectively simulate deep-well injection of
water-immiscible, gaseous or supercritical CO2.
Equations governing the radial injection of CO2 into deep
saline aquifers, its axisymmetric flow around the injector
and eventual buoyancy-driven floating with simultaneous
dissolution were formulated. The effect of pertinent fluid,
reservoir and operational characteristics on the deep-well
injection of CO2 was investigated. Shown in Figures 1
through 4 are some key findings from simulations using
PNLCARB1.0 and STOMP-CO2. Results indicate that
the injected CO2 phase initially grows as a bubble radially
outward, dissolves partially in the formation waters,
eventually floats toward the top due to buoyancy, and
settles near the top confining layer. Formation
permeability, porosity, the rate and pressure of injection,
and the rate of dissolution of CO2 influence the growth
and ultimate distribution of the CO2 phase.
Radius of CO2 bubble (Km)
10
8
6
4
2
Sg=0.095
0.195
0.295
0.395
0.495
0.595
0.695
0.795
0.895
0
0 8000 16000 24000 32000 40000
Time (days)
Figure 1. CO 2 saturation profiles at thousands of days after
injection
234 FY 2000 Laboratory Directed Research and Development Annual Report
CO 2 saturation, S g
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0 2000 4000 6000 8000 10000 12000 14000
Radial distance, rs (m)
Publication
Eq. 8
Eq. 4
Figure 2. As a function of radial distance away from well
Height of CO 2 -water contact (m)
120
0 5000 10000 15000 20000
Radial distance from well (m)
Figure 3. Effect of injection rate on ultimate CO2-water contact
120
100
80
60
40
20
160
140
Qc=27540 m 3 /d
Qc=275400 m 3 /d
50 100 150 200
Figure 4. CO 2 bubble growth prediction by STOMP-CO 2 at
a low flow rate
Saripalli P. 2000. Simulations using PNLCARB1.0 to
model deep-well injection of CO2 for geological
sequestration at Mt. Simon Site. Prepared for BCO
Columbus, as a part of model validation effort for
DOE-FE funded research project.
A