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By Gerhard Zacher (GE Sensing & Inspection Technologies)
Citation preview
Evaluation of Rock Properties and Rock Structures in the µ-range with sub-µ X-ray
Computed Tomography
Gerhard Zacher1, Matthias Halisch², Thomas Mayer1
1) GE Sensing & Inspection Technologies, Wunstorf, Germany
²) Leibniz Institute for Applied Geophysics, Hannover, Germany
Avizo Meeting, Bordeaux, May 31, 2012
2 /GE /
Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
3 /GE /
X-ray tubes Microfocus - nanofocus
Introduction & Fundamentals
4 /GE /
RequirementsGeometry and Resolution
M=FDD/FOD
U=(M-1)F (on the detector)
Vx=P/M
detector pixel P<< U
F predominates resolution
detector pixel P >> U
Pixel- / Voxelsize predominates resolution
Introduction & Fundamentals
5 /GE /
Resolution and Detail DetectabilityDetail detectability of the nanofocus tube
Conclusion:
detail detectability
is no measure
for sharpness
Focal Spot ≈2.5 µm ≈ 0.8 µm
500 nm 500 nm
5 µm 5 µm
Introduction & Fundamentals
6 /GE /
Resolution and Detail DetectabilityResolution
2 µm bars 2 µm bars
≈2.5 µm ∅
Focal spot size influence:
≈1.5 µm ∅ ≈0.8 µm ∅
0.6 µm bars
Introduction & Fundamentals
7 /GE /
Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
8 /GE /
nanotom multra-high resolution
nanoCT system
X-ray tube: nanofocus < 800 nm spot size180 kV / 15 W, tube cooling
X-ray detector:Cooled flat panel, 7.4 Mpixel,11 Mpixel virtual detector100 µm pixel size
Manipulator:5 axis stepper motors, granite-based, high-precision air bearing
Nanotom CT / resolution comparison
9 /GE /
Principle of CT
Acquisition
of projections during step-by-steprotation by 360°
Steps < 1°
Nanotom CT / resolution comparison
The acquisition of radiographic data is the elementary measuring process in CT
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Principle of CT: Reconstruction MethodExample: spark plug
back-projectionprojection inversion log + filter lineprofile
Acquisition of 600 projections 600 back projections 3D visualization
nanotom CT / resolution comparison
11 /GE /
nanoCT microCT
Image resolution:
nanoCT: < 1 µm microCT: ≈4 µm
microfocus CT vs.nanofocusCTof a dried fern
Nanotom CT / resolution comparison
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nanofocusCT
of a dried fern
• Example for resolving smallest features≤ 1µm
Nanotom CT / resolution comparison
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Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
14 /GE /
Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Scan data of geological samples
1 mm
A
BAA
BB
A
B
Bentheimer sandstone
3D volume of CT scan. Quartz (grey), (A) clay (brown), (B) feldspar (blue) and high absorbing minerals (red). Right: pore space is separated (green)
15 /GE /
Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Scan data of geological samples
Bentheimer sandstone
Electron microscope images of clay aggregation (left) and highly weathered feldspar (right)
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Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Scan data of geological samples
Bentheimer sandstone
1 mm
Comparison of CT result (left) and thin section (right). Histogram shows several peaks for different phases (air, clay (Illite), quartz, feldspar, denser minerals.
feldspar
17 /GE /
Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
1 mm
Scan data of geological samples
Bentheimer sandstoneIncreasing inhomogeneity of samples
Representative?
���� Scaleproblem?
For different sandstones (Bentheimer, Oberkirchenerand Flechtinger) porosity has been evaluated by different methods. Range differs a lot.
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Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Scan data of geological samples
Bentheimer sandstone
Mittlere Porosität: ~ 22.5 %Repräsentatives Scan-Volumen: 1000x1000x1000 Voxel
Mittlere Porosität: ~ 7 %Repräsentatives Scan-Volumen: > 1750x1750x1750 Voxel
1 mm
Bentheimer Sandstone Flechtingen Sandstone
Porosity (CT) with respect to volume size for different sandstones
19 /GE /
Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Avizofluid flow simulation
Scan data of geological samples
Bentheimer sandstoneoutlook
• Further linking CT informationen to rock physik:• inner surface• pore size distribution / NMR
• Preparation of CT data for modelling (pore scale)
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Bentheimersandstone(Ø 5 mm)
Vx = 1 µm
Avizofluid flow simulation
Scan data of geological samples
Bentheimer sandstonevideo
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pyroclastic rock (Ø 1 mm)
Vx = 1 µm
yz-slice
1 mm
Scan data of geological samples
yz-slice with different grains with high porosity or fractures and bigger pores
3mm
zoomedarea
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1 mm
Scan data of geological samples
Zoom into yz-slice with measurement of thin wall: 1.8 µm
3mm
pyroclastic rock (Ø 1 mm)
Vx = 1 µm
yz-slice
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Etna pyroclastic rock (fresh’11)(Ø 10 mm)
Vx = 5 µm
xy-slice
1 mm
Scan data of geological samples
xy-slice through 5x5x5mm cube used later for flow simulation
3mm
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1 mm
Scan data of geological samples
3mm
Etna pyroclastic rock (fresh’11)(Ø 10 mm)
Vx = 5 µm
3D volume
The surface is composed of 18 Mio. faces and represents the stone matrix. Shadows enhance the spatial impression.
Etna pyroclastic rock
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1 mm
Scan data of geological samples
3mm
Etna pyroclastic rock (fresh’11)(Ø 10 mm)Vx = 5 µm
Avizofluid flow simulation
The colored volume rendering shows the velocity’s magnitude within the pore space. The particle plot shows the actual vector field using cones.
Etna pyroclastic rock
26 /GE /
1 mm
Scan data of geological samples
3mm
Etna pyroclastic rock
The pore space is visualized with volume rendering. The matrix’ thickness has been calculated and is visualized on the surface.
Etna pyroclastic rock (fresh’11)(Ø 10 mm)Vx = 5 µm
Avizowall thickness
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1 mm
Scan data of geological samples
3mmThe color slice intersects the velocity field calculated with XLab Hydro and visualizes the vector field. Colors give the velocity’s magnitude.
Etna pyroclastic rockEtna pyroclastic rock (fresh’11)(Ø 10 mm)Vx = 5 µm
Avizofluid flow simulation
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3D view of a Nummulite Lower Eocene 53 million years old(Ø 2 mm)
Courtesy of
R. Speijer, K.U.
Leuven, Belgium
Vx = 1 µm
1 mm
Scan data of geological samples
Transparent 3D view
3mm
29 /GE /
3D view of a Nummulite Lower Eocene 53 million years old(Ø 2 mm)
Courtesy of
R. Speijer, K.U.
Leuven, Belgium
Vx = 1 µm
1 mm
Scan data of geological samples
Sliced 3D view to show the delicate internal structures
30 /GE /
Slice view of a Nummulite Lower Eocene 53 million years old(Ø 2 mm)
Courtesy of
R. Speijer, K.U.
Leuven, Belgium
Vx = 1 µm
1 mm
Scan data of geological samples
Xy slice through center plain
zoomedarea
31 /GE /
Slice view of a Nummulite Lower Eocene 53 million years old(Ø 2 mm)
Courtesy of
R. Speijer, K.U.
Leuven, Belgium
Vx = 1 µm
1 mm
Scan data of geological samples
Zoomed xy slice through center plain with measured pore 2.3 µm
3mm
32 /GE /
Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
33 /GE /
Conclusions
• State of the art high resolution tube based X-ray CT with the phoenix nanotom offers
• Comparable (or higher) spatial resolution to SRµCT setups due to nanofocus tube (ease of use, lower cost and faster analysis)
• Wide variety of geological samples can be analysed
• Data of a whole 3D volume offers numerous qualitative AND quantitative interpretations
• New insights in rock materials for geo science
34 /GE /
Outlook
• More quantitative data analysis (like permeability, particle size distribution, density distribution, …)
• More input from geoscientists to better generate the potential of nanofocus X-ray CT
35 /GE /
Contact and further information:
www.phoenix-xray.comor
www.ge-mcs.com/phoenix