Post on 13-Dec-2015
Ran Qi, Valcir T Beraldo, Tara C LaForce, Martin J Blunt
Design of CO2 storage in aquifers
17th Jan. 2008 Imperial College Consortium on Pore-Scale Modelling Project Meeting
SPE-109905
Outline
Background
Objectives
Streamline method for CO2 transport
Simulation results
Conclusions
Future work
SPE-109905Mobile CO2 saturation
Z
170m
X3200m
Y
2280m
Trapped CO2 saturation
X3200m
Y
2280m
Z
170m
Background
Carbon Capture and Storage (CCS)
736 Gt in North Sea alone (DTI) ≈CO2 produced by all UK population for 100 years!!! SPE-109905
Objectives
Understanding of physical process of CO2 storage, especially trapping, in aquifers and oil fields
• Extend streamline-based simulator
• Apply results from pore-scale modeling
General design of injection strategy
• Aquifers - maximize CO2 storage
SPE-109905
Overview of the streamline method
Permeability field
Initial saturation
Pressure solve
SL tracing
Saturation along SL
Saturation for the next
time stepSPE-109905
Streamline method for CO2 transport
Hydrocarbon phase Aqueous phase
Todd&Longstaff
Fingering model for CO2 in oilSPE-109905
Phases (3) Components (4)
Hydrocarbon
Aqueous
Solid
CO2
Oil
Water Salt
+
+
+
+
+
+
+
+
+
Streamline method for CO2 transport
•Chemical reaction1D vertical discretization
•Gravity solution •Dissolution
KD: Spycher et al (2003, 2005)
SPE-109905
Streamline method for CO2 transport
Trapping model
Pore-scale model matches experimental data.• Kr is from Berea sandstone, which matches Oak (1990)’s
experiments.• CO2/water system is weakly water-wet (Chiquet et al., 2007)
contact angle (θ) = 65º.
New trapping model (Juanes et al., 2006)
2maxmaxgggt SSS
))((4
)1(1
2
1max
2
gggtggtggf
SSSSSSS
SPE-109905
Design of carbon dioxide storage
The ratio of the mobility of injected brine and CO2 to the formation brine as a function of the injected CO2-phase volume fraction, fgi.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
S g
f g
Series1
fgi=0.85Sgi=0.26
fgi=0.5Sgi=0.19
f gi = 0.5
Sgi = 0.190
f g
f gi = 0.85
Sgi = 0.295
The CO2-phase fractional flow fg as a function of CO2 (gas) saturation, Sg.
SPE-109905
0.01
0.1
1
10
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
f ci
Mob
ility
rat
io
Mobility ratio between carbon dioxide/brine mixture and formation brine
Mobility ratio between chase brine and carbon dioxide/brine mixture during chase brine injection
Mobility ratio = 1.0
fgi
Design of carbon dioxide storage
1D analysis: Numerical simulation vs. analytical solution
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0 200 400 600 800 1000 1200 1400
Distance (m)
Sg
Simulation
Analyticalsolution
Trapped CO2 Mobile CO2
Dissolution front
Advancing CO 2 front
Chase brine front
fgi = 0.5
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 200 400 600 800 1000 1200 1400
Distance (m)
Sg
Simulation
Analytical solution
Trapped
CO2
Mobile CO2
Dissolution front
Advancing CO 2 front
Chasebrine front
fgi = 0.85
SPE-109905
Design of carbon dioxide storage
Mobile CO2 saturation
Z
170m
X3200m
Y
2280m
Trapped CO2 saturation
X3200m
Y
2280m
Z
170m
Injector
Producer
SPE 10 reservoir model, 1,200,000 grid cells (60X220X85), 7.8 Mt CO2 injected.
Two years after chase water injection for fgi=0.85.
SPE-109905
Design of carbon dioxide storage
3D simulation: Storage efficiency vs. trapping efficiency
Storage efficiency =
the fraction of the reservoir pore volume filled with CO2
Trapping efficiency =
the fraction of the injected mass of CO2 that is either trapped or dissolved
SPE-109905
The storage efficiency is highest for fgi = 0.85, which also requires minimum mass of chase brine to trap 95% of CO2.
0.1
0.3
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
f ci
Rat
io o
f the
mas
s of
bri
ne in
ject
ed
to th
e m
ass
of C
O2
inje
cted
0.02
0.021
0.022
0.023
0.024
0.025
0.026
0.027
0.028
Sto
rage
eff
icie
ncy
Storage efficiency
Ratio of the mass of chase
brine injected to the mass of CO 2
Ratio of the total mass of brine injected to the mass of CO 2
Trapping efficiency
90% 95%
Mass ratio
fgi
Design Criterion
• Inject CO2+brine where mobility ratio = 1.0
(fgi=0.85 in this example).
• Inject chase brine that is 25% of the initially injected CO2 mass.
• 90-95% of the CO2 is trapped.
SPE-109905
Conclusions
• Streamline-based simulator has been extended to model CO2 storage in aquifers and oil reservoir by incorporating a Todd-Longstaff model, equilibrium transfer between phases (dissolution) and rate-limited reaction;
• Trapping is an important mechanism to store CO2 as an immobile phase. Our study showed that WAG CO2 injection into aquifer can trap more than 90% of the CO2 injected;
• We have proposed a design strategy for CO2 storage in aquifers, in which CO2 and formation brine are injected simultaneously followed by chase brine.
• Streamline-based simulation combined with pore-scale network modeling can capture both the large-scale heterogeneity of the reservoir and the pore-scale effects of trapping.
SPE-109905
Future work
Injection strategy design
• Field scale simulation using a combination of this extended streamline-based simulator and pore-scale modeling.
• Require better experimental data, since the trapping model used has a significant impact on the results.
• Design of an injection strategy to maximize CO2 storage and oil recovery.
SPE-109905