Water Injection in Fractured Reservoirs
Hassan Karimaie
Department of Petroleum Engineering and Applied Geophysics
NTNU
1
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Outline:
 Background
 Matrix / fracture system in fractured reservoirs
 Water injection in NFR







2
Normal procedure in industry: Immersion test or Amott test
Water rising in the fracture or Immersion?
Cocurrent and Counter current imbibition
Experiments
Results and discussion
Conclusion
References
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Background
 Unique feature of NFR:
 Early breakthrough of injected fluid
 More uniform fluid composition
 Small pressure drop
 Absence of transition zone
Matrix
Invaded Zone
Water
or
Gas
Oil
Fracture
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Analogue model
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5
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Problem Definition
Idealization of fractured porous media
Warren & Root model
6
Laboratory experiment:
Is immesrion test or Amott test the right experiment for NFR?
Oven
Oil
Recovered
Oil
Core
7
Brine
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Visual Observation (Single Block)
•Low
rate, No Counter-Current
•High
rate, Co-Current
•And Counter-current
•Very
High Rate
•Counter Current
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Cocurrent and counter current imibibition
1-Counter-Current Imbibition:
Water and oil flow through the same faces in opposite directions
Nonlinear Diffusion Eq.:
S w S w

( D( S w )
)
x
x
t
Water
Oil
(1)
Oil
2-Co-Current Imbibition:
Water and oil flow through the opposite faces in the same direction.
Nonlinear Convection- Diffusion Eq.:
S w
S w

( D( S w )
 qt f (S w )) 
x
x
t
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Water
(2)
Oil
Oil
Oil
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Capillary-Gravity ratio
(Schechter et al. 1994)
 /k
1
NB  C
gH
Oil
Water
•
Oil

Oil Water
When
 N B1  5
Oil
Capillary forces are dominant
Counter-current flow
 0.2  NB1  5 Both capillary and gravity forces
Oil
•
Oil
Oil
Co- and counter-current flow
 NB1  1
Gravity forces are Dominant
Co-current flow
Water
•
Oil
Oil
C = 0,4 for capillary tube model
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Water
Water injection in fractured media
Water wet sample
(Bentheimer sandstone)
Non-water-wet sample
(Limestone outcrop-Asmari,Iran)
Length (cm)
116
116 (stack of blocks)
Diameter (cm)
3.8
6.25
1400
0.5-1
23
15
Kerosene-brine
n-decane-brine
Permeability (md)
Porosity %
Fluid system
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Methodology: Experimental Set-up
rising water level
Co-current
Oil
Electronic
Balance
Oil
Oil
Co and counter current
Oil
Pressure
Transducer
Counter current
Pc- DATA
ACQUISITION
Oil
Water
Spacer
Water
Pump
Co-current and counter-curret imbibition test
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Methodology: Experimental Set-up
(immersion)
Oil
Brine
Counter current
Oil
Oil
Oil
Oil
Water
Screw
Spacer
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Counter-currentTest
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Results: water-wet sample
0.7
q=0.1 cc/min
q=0.5 cc/min
q=1 cc/min
q=5 cc/min
Immersion
0.6
Recovery %
0.5
0.4
0.3
0.2
0.1
0
1
10
100
1000
10000
Time, min
  0.22 g/cc
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N -B1  2.6
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Results: water-wet sample
0.6
Recovery, fraction
qq=0.5=cc/min
0.5 cm3/min
cc/min
qq=1 =
1.0 cm3/min
qq=5=cc/min5.0 cm3/min
0.4
0.2
0
0
0.5
  0.03 g/cc
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N -B1  31.8
1
1.5
2
2.5
3
PV Injected
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0.6
0.6
0.5
0.5
0.4
Recovery, fraction
Recovery, fraction
Results: water-wet sample
N  1  31 . 8
B
N 1  2 .6
B
q=0.5 cc/min
Heavy oil
0.3
Light oil
0.2
0.4
0.3
N  1  31 . 8
B
N 1  2 .6
B
Heavy oil
0.2
Light oil
q=1 cc/min
0.1
0.1
0
0
0
0.5
1
1.5
PV Injected
2
2.5
3
0
0.5
1
1.5
2
2.5
PV Injected
0.6
N  1  31 . 8
B
N 1  2 .6
B
Heavy oil
Recovery, fraction
Light oil
q=5 cc/min
0.4
0.2
0
16
0
0.2
0.4
0.6
0.8
1
PV Injected
1.2
1.4
1.6
1.8
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Conclusion
 Oil recovery due to water injection is highly influenced by
gravity.
 Co current and counter current flow may occur in NFR
depends on injecion rate, matrix block height, porosity,
permeability, density difference and interfacial tension.
 Depending on injection rate, co-current flow may be more
efficient than counter-current flow.
 Bond number is an important dimensionless number for
characterising co.current and counter-current flow.
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References:
• H. Karimaie. “Aspects of Water and Gas Injection in Fractured
Reservoirs”. Thesis for the degree of philosophiae doctor at NTNU.
December 2007. ISBN 978-82-471-5532-5, ISSN: 1503-818.
• H.Karimaie, O. Torsæter, M.R.Esfahani, M. Dadashpour and S.M.
Hashemi."Experimental Investigation of Oil Recovery during Water
Imbibition". Journal of Petroleum Science and Engineering (JPSE) 52
(2006) 297-304.
• H.Karimaie and O.Torsæter. "Effect of Injection Rate, Initial Water
Saturation and Gravity on Water Injection in Slightly Water-Wet
Fractured Porous Media". Journal of Petroleum Science and
Engineering (JPSE) 58 (2007) 2937-308.
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• Pooladi-Darvish, M and Firoozabadi. A. “Experiments and Modeling
of Water Injection in Water-Wet Fractured Porous Media”. JCPT
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volume 39, No.3. 2000 (March).