Christopher H Pentland, Stefan Iglauer, Yukie Tanino, Rehab El-Magrahby, Saleh K Al Mansoori, Puneet Sharma, Endurance Itsekiri, Paul Gittins, Branko Bijeljic, Martin J Blunt Capillary trapping - Experiments and Correlations

2 Outline 1.Motivation Why are we investigating capillary trapping – don’t we know about this already? 2.Experimental Approach & Results Sandpack experiments Coreflood experiments Micro-CT scanning 3.Future Work Reservoir condition experiments

3 Motivation - Trapping Equations Equation 1Land, 1968 Equation 2Jerauld, 1997 Equation 3Ma & Youngren, 1994 Equation 4Kleppe et al., 1997 Equation 5Aissaoui, 1983 Equation 6Spiteri et al., 2005 where

4 Motivation - Trapping Equations

5 Motivation - Carbon Capture and Storage (CCS)

6 Motivation –CCS Subsurface Trapping Mechanisms Carbon Storage - How can you be sure that the CO 2 stays underground? Dissolution CO 2 dissolves in water (p, T, salinity of brine) – 1,000-year timescales denser CO 2 -rich brine sinks Chemical reaction acid formed carbonate precipitation – 10 3 – 10 9 years Structural & Stratigraphic Trapping Trapping by impermeable cap rocks Capillary Trapping rapid (decades): CO 2 as pore-scale bubbles surrounded by water. Process can be designed: SPE Qi et al. host rock

7 Motivation – CCS Pilot Projects Source: The Bellona Foundation (

8 Motivation – CCS Pilot Projects 1. Spectra, Canada2003( Kt/y) 2. Fenn Big Valley, Canada1998(17.32 Kt/y) 3. Weyburn, Canada2000(1.80 Mt/y) 4. Salt Creek, USA2006(2.09 Mt/y) 5. Snøhvit, Norway2008( Kt/y) 6. Sleipner, Norway1996(1.01 Mt/y) 7. Schwarze Pumpe, Germany2008( Kt/y) 8. In Salah, Algeria2004(1.21 Mt/y) 9. Otway, Australia2008( Kt/y) Source: The Bellona Foundation (

9 EXPERIMENTS 1.Sandpack flooding experiments Ambient condition – octane/brine 2.Consolidated coreflood experiments Sandstones – octane/brine Carbonates – octane/brine 3.Micro-CT imaging dry samples octane//brine scCO2/brine 4.Reservoir condition coreflood experiments Sandstones – octane/brine Carbonates – octane/brine Sandstones – scCO2/brine Carbonates – scCO2/brine COMPLETED UNDERWAY PLANNING STAGE UNDERWAY PLANNING STAGE

10 Experiments - Sandpacks Simple, elegant initial investigation of capillary trapping Ambient conditions Octane/brine Air/brine High poro perm system (37% porosity; 32D permeability) Representative flow rates (Ncap ~ ) SPE

11 Experiments - Ambient Consolidated Coreflood (ongoing) Representative consolidated core plug samples Sandstones & carbonates Octane/brine Range of rock properties studied (e.g. porosity from 12% to 21%) Representative flow rates (Ncap ~ ) Doddington sandstone: »21% porosity »2D air perm Stainton sandstone: »17% porosity »50mD air perm St. Bees sandstone: »20% porosity »250mD air perm More samples under investigation (Berea etc)

12 Experiments - Residual saturation as a function of porosity Investigate link between rock properties and capillary trapping Porosity Permeability Aspect ratio Connectivity Pore size distribution

13 Experiments - Residual oil saturations as porosity functions our data best least square fit: quadratic (R = ) – Ф Ф 2 all data best least square fit: logarithmic (R = ) ln(Ф) SPE

14 Experiments - Capillary trapping capacity as porosity functions our data best least square fit: quadratic (R = ) Ф – Ф Ф 3 all data best least square fit: logarithmic (R = ) Ф( ln(Ф) ) Source: Iglauer et al., 2009 (SPE ) Capillary Trapping Capacity = ϕ S (nw)r SPE

15 Experiments - Micro-CT Imaging Small diameter samples allow for pore space to be imaged (sandstones) Displacement experiments have been performed (oil/water) and phase configuration visualised on the pore scale.

16 Micro-CT Imaging – 2D slice

17 Micro-CT Imaging – Doddington Sandstone a b c d A.Segmented 2D image B.Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm) C.Residual oil topology of a 30 slice stack D.Brine topology of a 30 slice stack Porosity = 21% Perm = 1.5D Sor = 32.9%

18 Micro-CT Imaging – Berea Sandstone a b c d A.Segmented 2D image B.Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm) C.Residual oil topology of a 30 slice stack D.Brine topology of a 30 slice stack Porosity = 18% Perm = 300mD Sor = 38%

19 Micro-CT Imaging – Clashach Sandstone a b c d A.Segmented 2D image B.Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm) C.Residual oil topology of a 30 slice stack D.Brine topology of a 30 slice stack Porosity = 13% Perm = 9mD Sor = 45%

20 Network Modelling Valvatne et al., 2004 (Transport in Porous Media) www3.imperial.ac.uk/earthscienceandengineering/research/perm/ porescalemodelling

21 FUTURE WORK

22 Background – CO 2 Properties Copyright © 1999 ChemicLogic Corporation, 99 South Bedford Street, Suite 207, Burlington, MA USA

23 JOGMEC Collaboration

24 JOGMEC Collaboration - Drainage Drainage front imaged by CT scans. Maximum initial scCO 2 saturation determined.

25 JOGMEC Collaboration – Secondary Imbibition Secondary imbibition front imaged by CT scans. Residual scCO 2 saturation determined.

26 JOGMEC Collaboration - Results Drainage front saturations calculated from CT numbers. S w decreasing. 1-S w = S nwi = 33% Imbibition front saturations calculated from CT numbers. S w increasing. 1-S w = S nw,r = 26% (1PV) 1-S w = S nw,r = 20% (3PV) Dissolution?

27 Future Work – Where next? How does the capillary trapping curve look for supercritical CO2-brine systems? Problems to overcome: Corrosion – special consideration for wetted parts Will scCO2 be wetting – impact on the use of porous plates? Mixing of scCO2 and brine Brine expelled scCO2 injected CO2 Sat. Length

28 Acknowledgements