2 Phase Measurement of Non-Wetting Phase Trapping

Stefan Iglauer, Saleh K Al-Mansoori, Christopher H Pentland, Branko Bijeljic, Martin J Blunt

2 Phase Measurement of Non-Wetting Phase Trapping

2

Outline

Outline

1. Background2. Motivation3. Experimental Overview4. Results5. Future work

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.

3

BackgroundCarbon 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.

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80 90 100

S (nw

) r(%

)

S(nw) i (%)

Chierici et al. (consolidated), 1963 Chierici et al. (unconsolidated), 1963Crowell et al., 1966 Delclaud (consolidated), 1991Delclaud (unconsolidated), 1991 Gef fen et al., 1953Jerauld, 1997 Kantzas et al., 2001Kleppe et al., 1997 Kralik et al., 2000Land (Berea), 1971 Land (Alundum), 1971Ma & Youngren, 1994 McKay, 1974Plug, 2007

5

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

• Which is the most effective storage mediumconsolidated or unconsolidated formations?

0

5

10

15

0 10 20 30 40 50 60 70 80 90 100

ΦS(n

w) r

(%)

S(nw) i (%)

Chierici et al. (consolidated), 1963 Chierici et al. (unconsolidated), 1963Crowell et al., 1966 Delclaud (consolidated), 1991Delclaud (unconsolidated), 1991 Gef fen et al., 1953Jerauld, 1997 Kantzas et al., 2001Kleppe et al., 1997 Kralik et al., 2000Land (Berea), 1971 Land (Alundum), 1971Ma & Youngren, 1994 McKay, 1974Plug, 2007

consolidated

unconsolidated

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

0

20

40

60

80

100

0 20 40 60 80 100So (%)

Dis

tanc

e fr

om to

p of

col

umn

(cm

)

Initial oil saturation curves (Soi)

Residual oil saturation curves (Sor) – post

waterfloodingGHGT-9

9

Oil-brine experiments - Experimental Results

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60 70 80 90

Sor

(%)

Soi (%)

Experiment 1

Experiment 2

Experiment 3

Experiment 4

GHGT-9

10

Experimental Results – Comparison with Trapping Equations

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60 70 80 90

Sor

(%)

Soi (%)

Experimental Data

Land Equation 1968 - Eq. 1

Jerauld Equation 1997 - Eq. 3

Ma & Youngren Equation 1994 - Eq. 4

Kleppe et al. Equation 1997 - Eq. 5

Aissaoui Equation 1983 - Eq. 6

Spiteri et al. Equation 2006 - Eq. 7

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

0

20

40

60

80

100

0 20 40 60 80 100

Sg (%)

Hei

ght f

rom

top

of c

olum

n (c

m)

Residual gas saturation curves (Sgr) – post waterflooding

Initial gas saturation curves

(Sgi)

13

Air-brine experiments - Experimental Results

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60 70 80Sgi (%)

S gr (

%)

14

Experimental Results – Trapping curves

GHGT-9

0

2

4

6

8

10

12

14

16

18

0 10 20 30 40 50 60 70 80 90

S(nw) i (%)

S (nw

) r (

%)

Experimental Gas Data

Experimental Oil Data

15

Experimental Results – Comparison with Literature Data

GHGT-9

0

5

10

15

0 10 20 30 40 50 60 70 80 90 100S(nw) i (%)

ΦS (

nw) r

(%

)

Chierici et al. (consolidated), 1963 Chierici et al. (unconsolidated), 1963Crowell et al., 1966 Delclaud (consolidated), 1991Delclaud (unconsolidated), 1991 Geffen et al., 1953Jerauld, 1997 Kantzas et al., 2001Kleppe et al., 1997 Kralik et al., 2000Land (Berea), 1971 Land (Alundum), 1971Ma & Youngren, 1994 McKay, 1974Plug, 2007 Our results (oil-water), 2008Our results (air-water), 2008

16

Future Work

•Consolidated mediaSandstone (started)Carbonates

• Reservoir conditions

• Supercritical carbon dioxide

• Study link between trapping and system variables:Pore size distributionIFT / contact angle

17

Acknowledgements

Shell-Imperial Grand Challenge on Clean Fossil FuelsADNOC

Thank you!

18

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

**

*1gi

grgi

SS

C S

*max

1 1gr

CS

where

*max

**

1 1*max *1 1 1 gr

gigr S

gr gi

SS

S S

**

*1

gigr

bgi

SS

a S

maxmaxgi

gr grgi

SS S

S

2or oi oiS S S