Saleh K Al-Mansoori, Stefan Iglauer, Christopher H Pentland, Martin J Blunt Three-Phase Measurements of Non-Wetting Phase Trapping Applied to Carbon Dioxide Storage

2 Background Studied extensively to measure the amount of residual gas saturation during reservoir displacements. Suggested low oil saturations during gas displacement (oil layers). Trapping experience: experimentally on water-wet consolidated media. Pervious work: a linked the reduction of S or to S gt, a = 0 – 1, (a = 0 oil-wet, water-wet) Showed: Three-Phase Flow in Literature:

3 Motivation Principal interest: gas and oil trapping by water with application to CO 2 storage Unconsolidated media Literature data for trapped gas saturation in consolidated systems.

4 Motivation Wide scatter in literature S (nw)i versus S (nw)r data. Trapping Capacity =  S (nw)r

5 Wetting phase – Brine (5wt% NaCl; 1wt% KCl) Non-wetting phase – n-octane and air Oil and brine rate= 5 mL/min (N cap =10 -5, 2x10 -5 ) Air injection rate = drainage gravity (different amounts of time) Saturated air with octane for 5 hours Controlled evaporation using long, narrow tube Experimental Set Up

6 Oil-gas-brine experiments - Experimental Procedure Pack column with sand Packing ratio used to give reproducible porosity Fully saturate column with brine (vertically) Fixed volume of brine and oil injected into the column (500 mL) Air enters from the top, oil and gas drain from bottom (gravity drainage) Column is left to drain for different amounts of time (17h, 2h, and 0.5h). Column is sliced for S gi /S oi or waterflooded to reach S gr /S or. Column is sliced and sampled. Analysis of saturations in each section done with gas chromatography, GC & mass balance. Thermal Conductivity Detector (TCD) allows water to be analysed Sand is carefully recovered and washed with de-ionized water, dry mass of sand is measured, weighed and measured V B each empty clean column section. Repeat (reproducibility)

7 Experimental Results: gravity drainage: 17 hour Residuals: Sw/Sor/Sgr saturation curves– post waterflooding Initials: Swi/Soi/Sgi saturation curves Results: Saturation profiles

8 Experimental Results: gravity drainage: 17 hour Results: Trapping curves a.Sgr Vs. Sgi b.Sor Vs. Soi c.Sor Vs. Sgi d.Sor Vs. Sgr e.Sgt Vs. Snr f.Snr Vs. Sni

9 Experimental Results: gravity drainage: 2 hour Results: Initials: Swi/Soi/Sgi saturation curves Residuals: Sw/Sor/Sgr saturation curves– post waterflooding Results: Saturation profiles

10 Experimental Results: gravity drainage: 2 hour Results: a.Sgr Vs. Sgi b.Sor Vs. Soi c.Sor Vs. Sgi d.Sor Vs. Sgr e.Sgt Vs. Snr f.Snr Vs. Sni Results: Trapping curves

11 Experimental Results: gravity drainage: 0.5 hour Results: Saturation profiles Initials: Swi/Soi/Sgi saturation curves Residuals: Sw/Sor/Sgr saturation curves– post waterflooding

12 Experimental Results: gravity drainage: 0.5 hour Results: Trapping curves a.Sgr Vs. Sgi b.Sor Vs. Soi c.Sor Vs. Sgi d.Sor Vs. Sgr e.Sgt Vs. Snr f.Snr Vs. Sni

13 Experimental Results: experiments 1-3 Results: Trapping curves b. Compiled S or vs. S oi a.Compiled S gr vs. S gi

14 Experimental Results – Comparison with Literature Data

15 Discussion and conclusions For high initial gas saturation, more gas is trapped in the presence of oil than in two-phase flow. The trapped oil saturation, while no higher than the maximum reached in two-phase flow, is higher than expected for low initial saturations. Different from results in consolidated media. Why? In unconsolidated media, in two-phase flow, there is little snap-off and hence little trapping. In three-phase flow, oil layer collapse traps oil easily. Trapped oil prevents direct contact of gas by water except by snap-off and so we see more trapping. Confirm this? Pore-scale modelling; further experiment at reservoir conditions and with consolidated media.

16 Acknowledgements ADNOC Shell-Imperial Grand Challenge on Clean Fossil Fuels Thank you!