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