SMR1 / 13

Schlumberger Public

Application of Avizo Fire image processing for substances investigation inside porous medium

A. Nadeev, I. Yakimchuk, D. Mikhailov, E. Chuvilin, D. Koroteev, D. Korobkov, V. ShakoSchlumberger Moscow Research

SMR2 / 13

Schlumberger Public

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:

μm – mass attenuation coefficient at given X-ray radiation (E) energy (cm2/g), ρ – material density (g/cm3)

)(Em

The best solutions is application of X-ray contrast agents –chemical composition change!

leII 0

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)

SMR3 / 13

Schlumberger Public

AimsExciting micro-CT images Additional/new measurements

• X-ray micro-CT based approach development for investigation of 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

SMR4 / 13

Schlumberger Public

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• 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

• Artificial and natural sandstones:• Samples contains ice and/or clay phases

SkyScan-1172 micro-CT scanner equipped by cooling stage

Sample

SMR5 / 13

Schlumberger Public

Method for contrast improvement: ice saturation with ions of heavy metal

Appropriate time for saturation of frozen sample with Pb2+ ions is about 1 week

Cooling chamber, T = - 6oC

Sample

Ice which contains ions of heavy metal

Diffusion coefficient ofPb(NO3)2 in ice is0.2×10-5 cm2/sec-1

(Fick’s Law)

1% Pb(NO3)2

SMR6 / 13

Schlumberger Public

Influence of heavy metal ions on ice visualization

Micro-CT images of ice contained sand samples without contrast agent (a) and saturated with lead ions (b)

spatialresolutionis 3.2m/pixel

averagegrain sizeis 300 m

SMR7 / 13

Schlumberger Public

Influence of heavy elements on clay visualization

spatial resolution is3.2 m/pixel

5% water based claysolution

Distribution of modified clay in dried (a) and wet sample (b)

a b

A+B- +C+D-

A+1-xC+

xB-

ToC

A+B- – clay and C+D- – contrastagent compounds

SMR8 / 13

Schlumberger Public

Application of Avizo Fire filters for reconstructed slice of sand sample

Experimental dataNon-Local Means Edge-Preserving

SMR9 / 13

Schlumberger Public

Image segmentation using Avizo Fire

Non-Local Means Edge-preserving

SMR10 / 13

Schlumberger Public

Avizo Fire permeability calculation (XLab Hydro application)

Permeability of rock is667 mD

Permeability of icesaturated rock is 83 mD

“Experimental” permeabilityin z direction for the model400x400x200 voxels:

SMR11 / 13

Schlumberger Public

Ice distribution analysis

Ice content, %

Cutting from 3D image of sample

Cylinder height = 6 mm, diameter = 3 mm

Pore size distribution for two cases (15% of humidity): rock matrix porosity and remain porosity

taking into account the pore ice

Sam

ple l

engt

h, µ

m

SMR12 / 13

Schlumberger Public

Clay distribution analysis

1 3 42

3

0

0.02

0.04

0.06

0.08

0.1

0.12

0 1 2 3 4 5 6

Conc

etra

tion

of c

lay

Length of sample, mm

1 2 4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5 6

Void

frac

tion,

%

Length from inlet, mm

1 2 3 4

There is a damage in sample inlet Spatial resolution is 3.2 m/pixel

3

SMR13 / 13

Schlumberger Public

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 icevisualization is applied ions solid state diffusion

• Bruker micro-CT scanner SkyScan 1172 equipped with cooling stage can be used forinvestigation unconsolidated or low consolidated reservoir rock, where ice in porous mediumplays role of natural cement

• Unconsolidated rock properties such as: porosity, pore size distribution, residual watersaturation and, finally, building adequate 3D digital model can be achieved in case of correctmatrix-ice segmentation due to Avizo Fire software application

• XLab Hydro extension of Avizo Fire 7.0.0 can be applied for permeability calculation ofphases invaded rock