Presentation on theme: "Martin Blunt, Branko Bijeljic, Tara C LaForce, Stefan Iglauer, Ran Qi, Saleh Al- Mansoori, Chris Pentland and Erica Thompson Impact of capillary trapping."— Presentation transcript:
Martin Blunt, Branko Bijeljic, Tara C LaForce, Stefan Iglauer, Ran Qi, Saleh Al- Mansoori, Chris Pentland and Erica Thompson Impact of capillary trapping on geological CO 2 storage
Background Long term fate, how can you be sure that the CO 2 stays underground?
Field scale - The streamline method Permeability field Initial saturation Pressure solve SL tracing Saturation along SL Saturation for the next time step
Streamline method for CO 2 transport Hydrocarbon phaseAqueous phase Todd&Longstaff Fingering model for CO 2 in oil Phases (3)Components (4) Hydrocarbon Aqueous Solid CO 2 Oil Water Salt
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)
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. 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
Design of carbon dioxide storage 1D analysis: Numerical simulation vs. analytical solution f gi = 0.5 f gi = 0.85
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.
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 The storage efficiency is highest for f gi = 0.85, which also requires minimum mass of chase brine to trap 95% of CO 2.
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 % of the CO 2 is trapped.
Issues arising from field scale simulation 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.
Future work Injection strategy design 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.
CT Scanning A homogeneous sandpack was compressed and the porosity was determined via mass balance (Φ = 38,93). A homogeneous sandpack was compressed and the porosity was determined via mass balance (Φ = 38,93). n-Heptane was injected; when no more brine was produced, another CT scan was performed at the irreducible water saturation, S wi. n-Heptane was injected; when no more brine was produced, another CT scan was performed at the irreducible water saturation, S wi. CO 2 was injected again. Gas injection was stopped when no more liquid production was observed. Another CT scan was taken. CO 2 was injected again. Gas injection was stopped when no more liquid production was observed. Another CT scan was taken. 30 pore volumes (PV) of brine were injected and a final CT scan was taken at the residual gas saturation S gr. 30 pore volumes (PV) of brine were injected and a final CT scan was taken at the residual gas saturation S gr. resolution 9 µm resolution 9 µm
Sandpack at irreducible water saturation Brine – blue Sand – red Oil - orange Oil penetrates on average mainly into the larger pores as expected by capillary pressure considerations. Thin water layer is visible on the rock surface as expected for quartz. Oil has penetrated into the middle of some pores.
Sandpack at residual gas saturation Brine –blue Sand – red CO 2 - yellow The largest CO 2 ganglia is continuously spread over the largest available pore. Though overall gas accumulates in the larger pores, a random distribution between large and medium size pores is observable. Several tiny gas bubbles are randomly distributed in the pore volume. Though they might originate from the segmentation process, it is thought that they are real.
Vertical column experiments – Sor vs. Soi Sand-packed columns were oriented vertically. 5 pore volumes of de-aired brine were injected to reach full saturation. Decane reservoir connected to top of columns and brine allowed to drain under gravity from the base. Decane enters the top of the column. No pumping. Equilibrium reached where both columns have a (theoretically) identical oil saturation profile versus height. One column removed for slicing and sampling – Soi. Second column has brine injected from the base, Brine sweeps oil leaving an Sor. Coulmn sliced and sampled. brine flow Oil flow brine flow COLUMN A - Soi COLUMN B - Sor
Vertical column experiments – Sor vs. Soi - results