Test and Core Permeability Test Permeability consistently higher than ...
Permeability in the Eye of the Beholder
Martin Kennedy FESAus and SPE
Lecture Tour 2009
Contents • • • • •
Definitions Fundamentals Measurements Estimation Reconciliation
Definitions COMPLEXITY Single phase Gas
Single Phase Gas
Reservoir Fluids
‘Ambient’ (Kair)
Overburden/Reservoir Pressure(kinf)
keff/krel
Thin Section Probe
SCALE
Core Plug
Whole Core WFT Well Test
EWT
Directional Properties k90
kmax
kv
Characteristics • Permeability – Dimensions L2 – 10-14 to 10+>7 mD – Tensor (Anisotropic) • Resistivity, acoustic properties
– Dominated by largest pores
1 D = 0.99 um2
• Porosity – Dimensionless – 0 to 0.5 – Scalar (Isotropic) • density, neutron capture
– All pores contribute equally
Permeability and Fluid Flow A
Q = Δp.a4 8Δl.μ = kAΔp Δl.μ So…
Δl
k = a4 8A
Porosity-Permeability (Capillary Bundles) Permeability-Porosity 10000
1000
100 k/mD
1mm tubes 0.1mm tubes 0.01mm tubes
10
Permeability-Pore Size
10000 1
1000 0.050
0.100 porosity
0.150
0.200
k/mD
0.1 0.000
100
tube pore 3% porosity tube pore 30% por
10
1
0.1 0.00001
0.0001 pore diameter/m
0.001
Fracture Permeability Q = Δp.h.w3 Flow through a slot 12Δl.μ
A
= kAΔp Δl.μ w h
Δl
permeability equation
k = h.w3 12A kif = w2 12
Intrinsic permeability of a fracture
Permeability Controls in Real Rocks
Field A
Field B Realisations of SEM Images from the Plover sands in the Browse Basin. (2mmx2mm). Although coarser grained, the B sand has fewer paths that are more tortuous.
Porosity = 0.18 Kh = 470mD
Porosity = 0.16 Kh = 2 mD Pore network models constructed from the SEM images
Measurement • Fluid has to move… – Laboratory – Test (including WFT)
• Uncertainty and Errors. – Measurement. – Geological.
• Scale. – – – – – –
Probe 1mD
model
5.00
10.00
15.00
20.00
25.00
30.00
But is this representative? 0.10
poro/% 700 600 500 flow
Kh/mD
100.00
400
IG porosity
300
homog
200 100
Lorenz Coefficient 0.55
0 0
1
2
3
4
pore space
5
6
7
Reservoir Rock Pure Dolomite 3 phases of dolomitisation. 3 Porosity Types: Micro-crystalline Inter-granular Vuggy (or Leached) 3 depositional settings Supratidal - micro-xt Intertidal - intergranular/Vuggy Sub-tidal - intergranular/Vuggy
Dolomite Reservoir: Description Based on Whole Core por-perm plot 1000
no vugs pin point vugs
10
small vugs medium vugs large vugs
1 0
0.05
0.1
0.15
0.2
0.1
60000
porosity
50000
flow capacity
Kh/mD
100
Net Average Poro = 4.3 pu N = 179 plugs 166 with k>1mD
40000 w hole core k-phi model
30000
homog. 20000 10000 0
Lorenz Coefficient = 0.89
0
5
10
pore space
15
Campos Basin: Test and Core Permeability Test Permeability consistently higher than Core (3 wells, 14 DSTs).
Note: This is Unusual in that the core data has not been averaged
Campos Basin Field kDST>kcore because… Most Core Data comes from Facies 2, Muddy Sand. The ‘H’ in kH is too small. (Core data averaging is not an issue here)
Fac.2
Fac.1
Connectivity and Permeability. 1 0.9 0.8
Connected Sa
0.7 x(2D)
0.6
x(3D) y(2D)
0.5
y(3D) vertical 3D
0.4
Kv(3D)
0.3 0.2 0.1 0 0
0.2
0.4
0.6
0.8
Sand/Shale
Sand connectivity for 2D and 3D realisations. After M. D. Jackson (et al) AAPG Bull 89(4) p507-528
1
Moving from 2D to 3D
1.1
0.9
connected san
0.7 flas x falz y flas z
0.5
het x het y het z
0.3
0.1
2D
3D
-0.1 model
Conclusion • Permeability is not just another property curve. – It has units and dimensions and is directional.
• It cannot be measured as a continuous curve. – Imposes a limit on accuracy. – Probe permeameter is as close as we get.
• Different scale measurements need not agree. – Depends on averaging applied to the finer scaled data. – Disagreements may actually be telling us about the reservoir.
Post-script: North Sea Chalk Ekofisk
Tor
1 um
Martin Kennedy FESAus and SPE
Lecture Tour 2009
Contents • • • • •
Definitions Fundamentals Measurements Estimation Reconciliation
Definitions COMPLEXITY Single phase Gas
Single Phase Gas
Reservoir Fluids
‘Ambient’ (Kair)
Overburden/Reservoir Pressure(kinf)
keff/krel
Thin Section Probe
SCALE
Core Plug
Whole Core WFT Well Test
EWT
Directional Properties k90
kmax
kv
Characteristics • Permeability – Dimensions L2 – 10-14 to 10+>7 mD – Tensor (Anisotropic) • Resistivity, acoustic properties
– Dominated by largest pores
1 D = 0.99 um2
• Porosity – Dimensionless – 0 to 0.5 – Scalar (Isotropic) • density, neutron capture
– All pores contribute equally
Permeability and Fluid Flow A
Q = Δp.a4 8Δl.μ = kAΔp Δl.μ So…
Δl
k = a4 8A
Porosity-Permeability (Capillary Bundles) Permeability-Porosity 10000
1000
100 k/mD
1mm tubes 0.1mm tubes 0.01mm tubes
10
Permeability-Pore Size
10000 1
1000 0.050
0.100 porosity
0.150
0.200
k/mD
0.1 0.000
100
tube pore 3% porosity tube pore 30% por
10
1
0.1 0.00001
0.0001 pore diameter/m
0.001
Fracture Permeability Q = Δp.h.w3 Flow through a slot 12Δl.μ
A
= kAΔp Δl.μ w h
Δl
permeability equation
k = h.w3 12A kif = w2 12
Intrinsic permeability of a fracture
Permeability Controls in Real Rocks
Field A
Field B Realisations of SEM Images from the Plover sands in the Browse Basin. (2mmx2mm). Although coarser grained, the B sand has fewer paths that are more tortuous.
Porosity = 0.18 Kh = 470mD
Porosity = 0.16 Kh = 2 mD Pore network models constructed from the SEM images
Measurement • Fluid has to move… – Laboratory – Test (including WFT)
• Uncertainty and Errors. – Measurement. – Geological.
• Scale. – – – – – –
Probe 1mD
model
5.00
10.00
15.00
20.00
25.00
30.00
But is this representative? 0.10
poro/% 700 600 500 flow
Kh/mD
100.00
400
IG porosity
300
homog
200 100
Lorenz Coefficient 0.55
0 0
1
2
3
4
pore space
5
6
7
Reservoir Rock Pure Dolomite 3 phases of dolomitisation. 3 Porosity Types: Micro-crystalline Inter-granular Vuggy (or Leached) 3 depositional settings Supratidal - micro-xt Intertidal - intergranular/Vuggy Sub-tidal - intergranular/Vuggy
Dolomite Reservoir: Description Based on Whole Core por-perm plot 1000
no vugs pin point vugs
10
small vugs medium vugs large vugs
1 0
0.05
0.1
0.15
0.2
0.1
60000
porosity
50000
flow capacity
Kh/mD
100
Net Average Poro = 4.3 pu N = 179 plugs 166 with k>1mD
40000 w hole core k-phi model
30000
homog. 20000 10000 0
Lorenz Coefficient = 0.89
0
5
10
pore space
15
Campos Basin: Test and Core Permeability Test Permeability consistently higher than Core (3 wells, 14 DSTs).
Note: This is Unusual in that the core data has not been averaged
Campos Basin Field kDST>kcore because… Most Core Data comes from Facies 2, Muddy Sand. The ‘H’ in kH is too small. (Core data averaging is not an issue here)
Fac.2
Fac.1
Connectivity and Permeability. 1 0.9 0.8
Connected Sa
0.7 x(2D)
0.6
x(3D) y(2D)
0.5
y(3D) vertical 3D
0.4
Kv(3D)
0.3 0.2 0.1 0 0
0.2
0.4
0.6
0.8
Sand/Shale
Sand connectivity for 2D and 3D realisations. After M. D. Jackson (et al) AAPG Bull 89(4) p507-528
1
Moving from 2D to 3D
1.1
0.9
connected san
0.7 flas x falz y flas z
0.5
het x het y het z
0.3
0.1
2D
3D
-0.1 model
Conclusion • Permeability is not just another property curve. – It has units and dimensions and is directional.
• It cannot be measured as a continuous curve. – Imposes a limit on accuracy. – Probe permeameter is as close as we get.
• Different scale measurements need not agree. – Depends on averaging applied to the finer scaled data. – Disagreements may actually be telling us about the reservoir.
Post-script: North Sea Chalk Ekofisk
Tor
1 um
