2 Phase Measurement of Non-Wetting Phase Trapping

1. 2 Phase Measurement of Non-Wetting Phase Trapping Stefan Iglauer, Saleh K Al-Mansoori, Christopher H Pentland, Branko Bijeljic,Martin J Blunt

2. Outline Why am I up here talking about (oil-brine and air-brine) sand packs? Because of….the importance of capillary trapping to CO2 storage Application to residual hydrocarbon saturations in producing fields and carbon storage. • Outline • Background • Motivation • Experimental Overview • Results • Future work

3. Background Carbon Storage - How can you be sure that the CO2 stays underground? • Dissolution CO2 dissolves in water (p, T, salinity of brine) – 1,000-year timescales denser CO2-rich brine sinks • Chemical reaction acid formed carbonate precipitation – 103 – 109 years • Hydrodynamic Trapping • Trapping by impermeable cap rocks • Capillary Trapping • rapid (decades): CO2 as pore-scale • bubbles surrounded by water. • Process can be designed: SPE 115663 Qi et al. host rock

4. Motivation • How effective is capillary trapping? What magnitude will the residual saturations be? • Existing literature data for oil/water & gas/water systems in both consolidated and unconsolidated systems.

5. consolidated unconsolidated Motivation • Wide scatter in literature S(nw)r versus S(nw)i data. • Which is the most effective storage medium • consolidated or unconsolidated formations? Trapping Capacity = ϕ S(nw)r

6. Experimental Set Up • 1m sand packed column (PMMA) • Wetting phase – Brine (5wt% NaCl + 1wt% KCl) • Non-wetting phase – n-Octane or air • Sand – LV60 (poro = 37%; perm = 32D) • Oil injection rate = 0.5ml/min (Ncap = 10-6) • Air injection rate = gravity drainage • Brine injection rate = 5ml/min (Ncap = 2 x 10-5)

7. Oil-brine experiments - Experimental Procedure • Pack column with sand • Packing ratio used to give reproducible porosity • Fully saturate column with brine • Known volume of oil injected into the column from the top • Different experiments performed – 30ml, 50ml, 80ml of n-Octane • Column is inverted and oil rises from the bottom due to density difference • Experiment ended when the first drop of oil reached the top of the column • Column positioned horizontally & either sliced for Soi or waterflooded to reach Sor. • Column sliced and sampled. Analysis of saturations in each section done with gas chromatography, GC. • Thermal Conductivity Detector (TCD) allows water to be analysed • Repeat (reproducibility)

8. Oil-brine experiments - Experimental Results Residual oil saturation curves (Sor) – post waterflooding Initial oil saturation curves (Soi) GHGT-9

9. Oil-brine experiments - Experimental Results GHGT-9

10. Experimental Results – Comparison with Trapping Equations

11. Air-brine experiments - Experimental Procedure • Pack column with sand • Packing ratio used to give reproducible porosity • Fully saturate column with brine • Air enters column by opening top and bottom to atmosphere (gravity drainage) • Draining time was 3 hours and 30 minutes • Column was either sliced for Sgi or waterflooded (from the bottom) to reach Sgr. • Column sliced and sampled. Saturation measurement of each section via mass balance. • Repeat (reproducibility)

12. Air-brine experiments - Experimental Results Residual gas saturation curves (Sgr) – post waterflooding Initial gas saturation curves (Sgi)

13. Air-brine experiments - Experimental Results

14. Experimental Results – Trapping curves GHGT-9

15. Experimental Results – Comparison with Literature Data GHGT-9

16. Future Work • Consolidated media Sandstone (started) Carbonates • Reservoir conditions • Supercritical carbon dioxide • Study link between trapping and system variables: Pore size distribution IFT / contact angle

17. Acknowledgements • Shell-Imperial Grand Challenge on Clean Fossil Fuels • ADNOC Thank you!

18. where Trapping Equations • Equation 1 Land, 1968 • Equation 3 Jerauld, 1997 • Equation 4 Ma & Youngren, 1994 • Equation 5 Kleppe et al., 1997 • Equation 6 Aissaoui, 1983 • Equation 7 Spiteri et al., 2005