By Alexander N. Nadeev (Schlumberger Moscow Research)

1. Application of Avizo Fire image
processing for substances investigation
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inside porous medium
A. Nadeev, I. Yakimchuk, D. Mikhailov, E. Chuvilin, D. Koroteev,
D. Korobkov, V. Shako
Schlumberger Moscow Research
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2. X-ray attenuation bases
The value of linear attenuation coefficient (LAC) of every substance depends
on chemical composition, material density and X-ray radiation energy:
  m (E)
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μm – mass attenuation coefficient at given X-ray radiation (E) energy (cm2/g),
ρ – material density (g/cm3)
I  I 0e  l
I – X-ray radiation intensity after l length propagation, I0 – initial X-ray radiation intensity,
μ – linear attenuation coefficient (cm-1), l – length of radiation propagation (cm)
The best solutions is application of X-ray contrast agents –
chemical composition change!
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3. Aims
Exciting micro-CT images Additional/new measurements
• X-ray micro-CT based approach development for investigation of
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phases distribution inside porous space of rock samples
• identification of possible ways to improve X-ray contrast of phases (ice,
gas hydrate, clays and etc.) in porous medium:
to avoid disturbance of distribution or phases properties change
• application of X-ray contrast agents for distribution analysis of phases in 2D
and 3D micro-CT images using Avizo Fire software
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4. Micro-CT experiment
• SkyScan-1172 (Bruker micro-CT, Belgium) micro-CT
scanner
• Parameters of our experiments:
• Source: 100 kV &100 A
• Filter: built-in Al+Cu
Sample
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• Pixel size resolution: 3.0-3.5 m
• 1200-1800 angular projections (3600)
• Modified Feldkamp reconstruction algorithm (Nrecon with
InstaRecon engine, GPU base reconstruction)
• Image processing and visualization: Avizo Fire 7.0.0, CTAn,
CTVox
• Special stages: SkyScan micro-CT cooling stage to
investigate ice saturated samples SkyScan-1172 micro-CT scanner equipped by
cooling stage
• Artificial and natural sandstones:
• Samples contains ice and/or clay phases
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5. Method for contrast improvement: ice saturation with ions of
heavy metal
Cooling chamber, T = - 6oC
Sample
Diffusion coefficient of
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Pb(NO3)2 in ice is
0.2×10-5 cm2/sec-1
(Fick’s Law) Ice which contains
ions of heavy metal
1% Pb(NO3)2
Appropriate time for saturation of frozen sample with Pb2+ ions is about 1 week
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6. Influence of heavy metal ions on ice visualization
 spatial
resolution
is 3.2
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m/pixel
 average
grain size
is 300 m
Micro-CT images of ice contained sand samples without contrast agent
(a) and saturated with lead ions (b)
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7. Influence of heavy elements on clay visualization
a b
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A+B- +C+D-
ToC
 spatial resolution is
A+1-xC+xB- 3.2 m/pixel
A+B- – clay and C+D- – contrast
agent compounds  5% water based clay
solution
Distribution of modified clay in dried (a) and wet sample (b)
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8. Application of Avizo Fire filters for reconstructed slice of sand sample
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Experimental data
Non-Local Means Edge-Preserving
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9. Image segmentation using Avizo Fire
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Non-Local Means Edge-preserving
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10. Avizo Fire permeability calculation (XLab Hydro application)
“Experimental” permeability
in z direction for the model
400x400x200 voxels:
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 Permeability of rock is
667 mD
 Permeability of ice
saturated rock is 83 mD
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11. Ice distribution analysis
Cutting from 3D image of sample
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Sample length, µm
Pore size distribution for two cases (15% of
humidity): rock matrix porosity and remain porosity
Ice content, % taking into account the pore ice
Cylinder height = 6 mm,
diameter = 3 mm
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12. Clay distribution analysis
1 23 4 1 23 4
0.12 1
0.9
Concetration of clay
0.1
3 0.8
Void fraction, %
0.08 0.7
0.6
0.06 0.5
0.4
0.04
0.3
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0.02 0.2
0.1
0 0
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Length of sample, mm Length from inlet, mm
1 2 3 4
 Spatial resolution is 3.2 m/pixel  There is a damage in sample inlet
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13. Summary
• Special approaches for improvement X-ray contrast of phases inside rock porous medium
were developed: clay contrasting is based on ions interchange/ adsorption reactions, for ice
visualization is applied ions solid state diffusion
Bruker micro-CT scanner SkyScan 1172 equipped with cooling stage can be used for
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•
investigation unconsolidated or low consolidated reservoir rock, where ice in porous medium
plays role of natural cement
• Unconsolidated rock properties such as: porosity, pore size distribution, residual water
saturation and, finally, building adequate 3D digital model can be achieved in case of correct
matrix-ice segmentation due to Avizo Fire software application
• XLab Hydro extension of Avizo Fire 7.0.0 can be applied for permeability calculation of
phases invaded rock
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