Christopher H Pentland, Stefan Iglauer, Yukie Tanino, Rehab El-Magrahby, Saleh K Al Mansoori, Puneet Sharma, Endurance Itsekiri, Paul Gittins, Branko Bijeljic, Martin J Blunt

Capillary trapping - Experiments and Correlations

2

Outline

Outline

1. Motivation• Why are we investigating capillary trapping – don’t we know about this already?

2. Experimental Approach & Results• Sandpack experiments

• Coreflood experiments

• Micro-CT scanning

3. Future Work• Reservoir condition experiments

3

Motivation - Trapping Equations

Equation 1 Land, 1968

Equation 2 Jerauld, 1997

Equation 3 Ma & Youngren, 1994

Equation 4 Kleppe et al., 1997

Equation 5 Aissaoui, 1983

Equation 6 Spiteri et al., 2005

**

*1gi

grgi

SS

C S

*max

11

gr

CS

where

*max

**

1 1*max *1 1 1 gr

gigr S

gr gi

SS

S S

**

*1

gigr

bgi

SS

a S

maxmax

gigr gr

gi

SS S

S

2or oi oiS S S

4

Motivation - Trapping Equations

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

S(nw)i

S(n

w)r

Land Equation

Aissaoui Equation

Jerauld Equation

Kleppe Equation

Spiteri Equation

Ma Equation

5

Motivation - Carbon Capture and Storage (CCS)

6

Motivation –CCS Subsurface Trapping Mechanisms

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 • Structural & Stratigraphic 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

7

Motivation – CCS Pilot Projects

Source: The Bellona Foundation (www.bellona.org/ccs)

8

Motivation – CCS Pilot Projects

1. Spectra, Canada 2003 (190.00 Kt/y)2. Fenn Big Valley, Canada 1998 (17.32 Kt/y)3. Weyburn, Canada 2000 (1.80 Mt/y)4. Salt Creek, USA 2006 (2.09 Mt/y)5. Snøhvit, Norway 2008 (665.00 Kt/y)6. Sleipner, Norway 1996 (1.01 Mt/y)7. Schwarze Pumpe, Germany 2008 (100.00 Kt/y)8. In Salah, Algeria 2004 (1.21 Mt/y)9. Otway, Australia 2008 (104.72 Kt/y)

1

2 3

4

5

6

7

8

9

Source: The Bellona Foundation (www.bellona.org/ccs)

9

EXPERIMENTS1. Sandpack flooding experiments

• Ambient condition – octane/brine

2. Consolidated coreflood experiments• Sandstones – octane/brine• Carbonates – octane/brine

3. Micro-CT imaging• dry samples• octane//brine • scCO2/brine

4. Reservoir condition coreflood experiments• Sandstones – octane/brine• Carbonates – octane/brine• Sandstones – scCO2/brine• Carbonates – scCO2/brine

COMPLETED

UNDERWAYUNDERWAY

UNDERWAYUNDERWAYPLANNING STAGE

UNDERWAY PLANNING STAGE PLANNING STAGE PLANNING STAGE

10

Experiments - Sandpacks

Simple, elegant initial investigation of capillary trapping• Ambient conditions• Octane/brine• Air/brine• High poro perm system (37% porosity; 32D permeability)• Representative flow rates (Ncap ~ 10-7)

SPE 115697

11

Experiments - Ambient Consolidated Coreflood (ongoing)

Representative consolidated core plug samples• Sandstones & carbonates• Octane/brine• Range of rock properties studied (e.g. porosity from 12% to 21%)• Representative flow rates (Ncap ~ 10-7)

0

20

40

60

80

100

0 20 40 60 80 100

Soi (%)

So

r (%

)

Doddington Stainton St. Bees• Doddington sandstone:

» 21% porosity» 2D air perm

• Stainton sandstone:» 17% porosity» 50mD air perm

• St. Bees sandstone:» 20% porosity» 250mD air perm

• More samples under investigation (Berea etc)

1212

Experiments - Residual saturation as a function of porosity

Investigate link between rock properties and capillary trapping• Porosity• Permeability• Aspect ratio• Connectivity• Pore size distribution

1313

Experiments - Residual oil saturations as porosity functions

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.1 0.2 0.3 0.4 0.5

porosity

resi

dual

oil

sat

urat

ion

measurements

quadratic fit

logarithmic fit

exponential

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5

porosity

resi

dual

oil

sat

urat

ion

measurements

quadratic fit

logarithmic fit

exponential

our databest least square fit: quadratic (R = 0.9876)0.9043 – 3.7628 Ф + 4.3837 Ф2

all databest least square fit: logarithmic (R = 0.8888)-0.3025 ln(Ф) - 0.1365

SPE 120960

1414

Experiments - Capillary trapping capacity as porosity functions

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 0.1 0.2 0.3 0.4

porosity

Cap

illa

ry tr

appi

ng c

apac

ity

.

exponential

quadratic

logarithmic

measurements

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

porosityC

apil

lary

trap

ping

cap

acit

y .

exponential

quadratic

logarithmic

measurements

our databest least square fit: quadratic (R = 0.8525)0.9043 Ф – 3.7628 Ф2 + 4.3837 Ф3

all databest least square fit: logarithmic (R = 0.4432)Ф(-0.3025 ln(Ф) - 0.1365)

Source: Iglauer et al., 2009 (SPE 120960)

Capillary Trapping Capacity = ϕ S(nw)r

SPE 120960

15

Experiments - Micro-CT Imaging

• Small diameter samples allow for pore space to be imaged (sandstones)

• Displacement experiments have been performed (oil/water) and phase configuration visualised on the pore scale.

16

Micro-CT Imaging – 2D slice

17

Micro-CT Imaging – Doddington Sandstone

a b

c d

A. Segmented 2D image

B. Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm)

C. Residual oil topology of a 30 slice stack

D. Brine topology of a 30 slice stack

Porosity = 21%

Perm = 1.5D

Sor = 32.9%

18

Micro-CT Imaging – Berea Sandstone

a b

c d

A. Segmented 2D image

B. Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm)

C. Residual oil topology of a 30 slice stack

D. Brine topology of a 30 slice stack

Porosity = 18%

Perm = 300mD

Sor = 38%

19

Micro-CT Imaging – Clashach Sandstone

a b

c d

A. Segmented 2D image

B. Segemented 3D image - rock removed (300x300 voxels; 2.7mmx2.7mm)

C. Residual oil topology of a 30 slice stack

D. Brine topology of a 30 slice stack

Porosity = 13%

Perm = 9mD

Sor = 45%

20

Network Modelling

Valvatne et al., 2004 (Transport in Porous Media)

www3.imperial.ac.uk/earthscienceandengineering/research/perm/porescalemodelling

21

FUTURE WORK

22

Background – CO2 Properties

Copyright © 1999 ChemicLogic Corporation, 99 South Bedford Street, Suite 207, Burlington, MA 01803 USA

2323

JOGMEC Collaboration

2424

JOGMEC Collaboration - Drainage

• Drainage front imaged by CT scans. Maximum initial scCO2 saturation determined.

2525

JOGMEC Collaboration – Secondary Imbibition

• Secondary imbibition front imaged by CT scans. Residual scCO2 saturation determined.

2626

Wet scCO2 injection

0.60

0.70

0.80

0.90

1.00

0 20 40 60 80

Position, mm

Sw

0

0.2129

0.3193

0.4258

0.5322

0.6386

0.8456

0.9521

1.2359

2.2412

3.2465

4.2517

JOGMEC Collaboration - Results

• Drainage front saturations calculated from CT numbers. Sw decreasing.

• 1-Sw = Snwi = 33%

• Imbibition front saturations calculated from CT numbers. Sw increasing.

• 1-Sw = Snw,r = 26% (1PV)

• 1-Sw = Snw,r = 20% (3PV) Dissolution?

Water flood

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

0 20 40 60 80

position

Sw

4.2517

0

0.020591341

0.041182682

0.061774023

0.082365364

0.102956705

0.144139388

0.19561774

0.298574446

0.401531151

0.453009504

0.504487856

0.607444562

0.706282999

1.00279831

3.000158395

27

Future Work – Where next?

• How does the capillary trapping curve look for supercritical CO2-brine systems?

•Problems to overcome:• Corrosion – special consideration for wetted parts• Will scCO2 be wetting – impact on the use of porous plates?• Mixing of scCO2 and brine

Brin

e

expelle

d

scCO

2

inje

cted

CO

2

Sat.

Length

28

Acknowledgements