1. Ran Qi, Valcir T Beraldo, Tara C LaForce, Martin J Blunt Design of CO 2 storage in aquifers 17 th Jan. 2008 Imperial College Consortium on Pore-Scale Modelling Project Meeting SPE-109905

2. Outline Background Objectives Streamline method for CO 2 transport Simulation results Conclusions Future work SPE-109905 Mobile CO 2 saturation Z 170m X 3200m Y 2280m Trapped CO 2 saturation X 3200m Y 2280m Z 170m

3. Background Carbon Capture and Storage (CCS) 736 Gt in North Sea alone (DTI) ≈ CO 2 produced by all UK population for 100 years!!! SPE-109905

4. Long-term fate How can you be sure that the CO 2 stays underground?

5. Objectives Understanding of physical process of CO 2 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 CO 2 storage SPE-109905

6. Overview of the streamline method Permeability field Initial saturation Pressure solve SL tracing Saturation along SL Saturation for the next time step SPE-109905

7. Streamline method for CO 2 transport Hydrocarbon phaseAqueous phase Todd&Longstaff Fingering model for CO 2 in oil SPE-109905 Phases (3)Components (4) Hydrocarbon Aqueous Solid CO 2 Oil Water Salt + + + + + + + + +

8. Streamline method for CO 2 transport Chemical reaction 1D vertical discretization Gravity solution Dissolution K D : Spycher et al (2003, 2005) SPE-109905

9. Streamline method for CO 2 transport Trapping model Pore-scale model matches experimental data. Kr is from Berea sandstone, which matches Oak (1990)’s experiments. CO 2 /water system is weakly water-wet (Chiquet et al., 2007) contact angle (θ) = 65º. New trapping model (Juanes et al., 2006) SPE-109905

10. Design of carbon dioxide storage The ratio of the mobility of injected brine and CO 2 to the formation brine as a function of the injected CO 2 -phase volume fraction, f gi. The CO 2 -phase fractional flow f g as a function of CO 2 (gas) saturation, S g. SPE-109905 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 f gi

11. Design of carbon dioxide storage 1D analysis: Numerical simulation vs. analytical solution f gi = 0.5 f gi = 0.85 SPE-109905

12. Design of carbon dioxide storage Mobile CO 2 saturation Z 170m X 3200m Y 2280m Trapped CO 2 saturation X 3200m Y 2280m Z 170m Injector Producer SPE 10 reservoir model, 1,200,000 grid cells (60X220X85), 7.8 Mt CO 2 injected. Two years after chase water injection for f gi =0.85. SPE-109905

13. Design of carbon dioxide storage 3D simulation: Storage efficiency vs. trapping efficiency Storage efficiency = the fraction of the reservoir pore volume filled with CO 2 Trapping efficiency = the fraction of the injected mass of CO 2 that is either trapped or dissolved SPE-109905 The storage efficiency is highest for f gi = 0.85, which also requires minimum mass of chase brine to trap 95% of CO 2. f gi

14. Design Criterion Inject CO 2 +brine where mobility ratio = 1.0 (f gi =0.85 in this example). Inject chase brine that is 25% of the initially injected CO 2 mass. 90-95% of the CO 2 is trapped. SPE-109905

15. Conclusions Streamline-based simulator has been extended to model CO 2 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 CO 2 as an immobile phase. Our study showed that WAG CO 2 injection into aquifer can trap more than 90% of the CO 2 injected; We have proposed a design strategy for CO 2 storage in aquifers, in which CO 2 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

16. 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 CO 2 storage and oil recovery. SPE-109905

17. Acknowledgement Schlumberger – Faculty for the Future SHELL – Shell-Imperial Grand Challenge on Clean Fossil Fuels Thank you! SPE-109905