1. CPGE Department Seminar, Apr 18, 2011 Petroleum and Geosystems Engineering The University of Texas at Austin Austin, TX How the pore scale affects the field scale: Real world examples David A. DiCarlo

2. CPGE Department Seminar, Apr 18, 2011 Acknowledgments Stanford University Akshay Sahni Martin Blunt University of Texas Hassan Dehghanpour Behdad Aminzadeh Mohammad Mirzaei

3. CPGE Department Seminar, Apr 18, 2011 Variety of flow scales Continuum ScalePore ScaleField Scale Gas Oil

4. CPGE Department Seminar, Apr 18, 2011 Interests and motivation The configuration of fluids at the pore-scale controls flow and transport at field scales Three-phase (gas, oil, water) flow Preferential flow Unsaturated flow in fractures In-situ measurements of pore filling Fluid-fluid interfacial area in porous media Continuum and discrete formulations of flow

5. CPGE Department Seminar, Apr 18, 2011 NAPL Water Three-phase (gas, oil, water) flow Essential component of oil recovery or aquifer remediation Gas Oil Oil recovery by gas injection Leaking gasoline Key parameters: Residual oil (S or ) and flow speed (k ro )

6. CPGE Department Seminar, Apr 18, 2011 Prudhoe Bay’s extra oil At best, only 50% of the original oil in a reservoir is recovered by a waterflood Prudhoe Bay’s eventual recovery will be over 70%! (>$100 B difference) Why? Prudhoe Bay is the world’s largest gas injection operation

7. CPGE Department Seminar, Apr 18, 2011 Objectives Understand at a basic physical level why high recoveries are possible for three-phase flow Develop a quick method to measure three- phase relative permeability (normalized recovery rate) Systematically measure three-phase relative permeability as a function of wettability and saturation history

8. CPGE Department Seminar, Apr 18, 2011 Experimental set-up Create 1m long sandpacks with varying degrees of wettability Fill sandpacks with oil and water, then open the bottom and let drain out Use dual-energy computed tomography (CT) to measure the saturation of each phase versus position and time

9. CPGE Department Seminar, Apr 18, 2011 9 Experimental Set-up Oil phase  N-octane, Aqueous phase  10 wt % NaBr, Gas phase  Air Vertical Positioning System Effluent Gas Invades the System

10. CPGE Department Seminar, Apr 18, 2011 Long time saturation vs position and time – initial experiments

11. CPGE Department Seminar, Apr 18, 2011 Calculating Relative Permeabilities u i = -(K/  ) k r (S i )  P i /  x To directly measure the relative permeability of a phase you need The fluid saturation - S i The flux - u i The pressure gradient -  P i /  x

12. CPGE Department Seminar, Apr 18, 2011 Saturation vs Position and Time oil moved saturation

13. CPGE Department Seminar, Apr 18, 2011 Measured Relative Permeability Can measure relative permeability over 6 orders of magnitude Measure with different wettabilities Measure with different initial states

14. CPGE Department Seminar, Apr 18, 2011 Oil Permeability Remains Finite to Low Saturations Oil relative permeability depends on wettability

15. CPGE Department Seminar, Apr 18, 2011 Oil trapping after waterflood solid grain water trapped oil

16. CPGE Department Seminar, Apr 18, 2011 No oil trapping after gasflood oil layers gas

17. CPGE Department Seminar, Apr 18, 2011 Oil remains mobile to very low saturations Water becomes immobile at around S w = 0.1 Oil and water are not interchangeable

18. CPGE Department Seminar, Apr 18, 2011 Fluids on water-wet and oil-wet surfaces gw   ow go  go  gas water-wet surface oil water  g w  o w go  w a t e r o il gas gw  o il-w e t su rf ace Oil spreads on water Water beads on oil

19. CPGE Department Seminar, Apr 18, 2011 Fluids in pore corners Oil layers at low S o Oil cannot be trapped  go   ow o il gas w a t e r   ow gas  gw w a t e r o il water-wet corner oil-wet corner No water layers! Water can be trapped

20. CPGE Department Seminar, Apr 18, 2011 Layers Show up at Low Sat All oil in layers q ~ r 4 S o ~ A~ r 2 k ro ~ S o 2  go   ow o il gas w a t e r

21. CPGE Department Seminar, Apr 18, 2011 Current work – Three Phase Comparing results to Stone and saturated average three-phase permeability models Can possibly fit by changing the residuals Extending reconnection work to different wettabilities Measure pressures, and do with real rock cores and CO2 ?????

22. CPGE Department Seminar, Apr 18, 2011 Interests and motivation The configuration of fluids at the pore-scale controls flow and transport at field scales Three-phase (gas, oil, water) flow Preferential flow – flow at frontal interfaces Unsaturated flow in fractures In-situ measurements of nano-particles Surfactant imbibition into oil-wet media Continuum and discrete formulations of flow

23. CPGE Department Seminar, Apr 18, 2011 Thanks for your attention!