Three-Phase Measurements of Non-Wetting Phase Trapping Applied to Carbon Dioxide Storage

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 Sor to Sgt, a = 0 – 1, (a = 0 oil-wet, 0.45 - 0.75 water-wet)

• Showed:

Three-Phase Flow in Literature:

p3

gr

p2

or

p3

orSaSS

p2

or

p3

or SS

3

Motivation

• Principal interest: gas and oil trapping by water with application to CO2 storageUnconsolidated media

•Literature data for trapped gas saturation in consolidated systems.

0

5

10

15

20

25

30

35

40

0 10 20 30 40 50 60 70 80 90 100

S(nw) i (%)

S(n

w)

r (%

)

Caubit et al., 2004 - 3ph Jerauld - 1996 - 3phMaloney et al., 2002 - 3ph Skauge et al., 2002 - 3ph, Sgi > 0.40Skauge et al., 2002 - 3ph, Sgi < 0.40 Kralik et al., 2000 - 3phKyte et al., 1956 - 3ph Holmgren et al., 1951, 3ph, OilFloodsHolmgren et al., 1951, 3ph, GasExpansion

4

Motivation

• Wide scatter in literature S(nw)i versus S(nw)r data.

•Trapping Capacity = S(nw)r

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60 70 80 90 100

S(nw) i (%)

S

(nw

) r (%

)

Caubit et al., 2004 - 3ph Jerauld - 1996 - 3phMaloney et al., 2002 - 3ph Skauge et al., 2002 - 3ph, Sgi > 0.40Skauge et al., 2002 - 3ph, Sgi < 0.40 Kralik et al., 2000 - 3phKyte et al., 1956 - 3ph Holmgren et al., 1951, 3ph, OilFloodsHolmgren et al., 1951, 3ph, GasExpansion

5

Wetting phase – Brine (5wt% NaCl; 1wt% KCl)

Non-wetting phase – n-octane and air

Oil and brine rate= 5 mL/min (Ncap=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 Sgi/Soi or waterflooded to reach Sgr/Sor.

• 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 VB each empty clean column section.

• Repeat (reproducibility)

7

Experimental Results: gravity drainage: 17 hour

0

20

40

60

80

100

0 20 40 60 80 100S(nw) i (%)

Dis

tan

ce

(c

m)

0

20

40

60

80

100

0 20 40 60 80 100S(nw) r (%)

Dis

tan

ce

(c

m)

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:

0

20

40

60

80

100

0 20 40 60 80

S(nw) i (%)

Dis

tan

ce

(c

m)

0

20

40

60

80

100

0 20 40 60 80 100S(nw) r (%)

Dis

tan

ce

(c

m)

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

0

20

40

60

80

100

0 20 40 60 80 100

S(nw) i (%)D

ista

nc

e (

cm

)

0

20

40

60

80

100

0 20 40 60 80 100

S(nw) r (%)

Dis

tac

e (

cm

)

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 Sor vs. Soi

a. Compiled Sgr vs. Sgi

0

5

10

15

20

25

0 10 20 30 40 50 60 70 80 90 100

Sgi (%)

Sg

r (%

)

Sgr versus Sgi - 17 hrs

Sgr versus Sgi - 2 hrs

Sgr versus Sgi - 30 min

0

2

4

6

8

10

12

14

16

0 10 20 30 40 50 60 70 80 90 100

Soi (%)

So

r (%

)

Sor versus Soi - 17 hrs

Sor versus Soi - 2 hrs

Sor versus Soi - 30 min

14

Experimental Results – Comparison with Literature Data

0

5

10

15

20

25

30

35

40

0 10 20 30 40 50 60 70 80 90 100

S(nw) i (%)

S(n

w)r

(%

)

Caubit et al., 2004 - 3ph Jerauld - 1996 - 3phMaloney et al., 2002 - 3ph Skauge et al., 2002 - 3ph, Sgi > 0.40Skauge et al., 2002 - 3ph, Sgi < 0.40 Kralik et al., 2000 - 3phKyte et al., 1956 - 3ph Jerauld - 1997 - 2ph - SgroJerauld - 1997 - 2ph - Sgrw Maloney et al., 2002 - 2ph - SgrwSkauge et al., 2002 - 2ph Kralik et al., 2000 - 2phCaubit et al., 2004 - 2ph - Sgrw Caubit et al., 2004 - 2ph - SgroOur results, 2008 - 3ph Our results, 2008 - 2ph - SorwOur results, 2008 - 2ph - Sgrw Holmgren et al., 1951, 3ph, OilFloodsHolmgren et al., 1951, 3ph, GasExpansion

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!