porous rock evaluation with micro ct zacher_ge_copyright
TRANSCRIPT
Quantitative investigation of microstructures within porous rocks by using very high resolution X-ray
micro-CT imaging
Gerhard Zacher1, Matthias Halisch², Peter Westenberger3 andFrank Sieker1
1) GE Sensing & Inspection Technologies, Wunstorf, Germany
²) Leibniz Institute for Applied Geophysics, Hannover, Germany
³) FEI Visualization Sciences Group, Düsseldorf, Germany
Copyright General Electric 2014
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Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
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X-ray tubes Microfocus - nanofocus
Introduction & Fundamentals
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FundamentalsGeometry and Resolution
Advantage of nanofocus tube:resolution & Penumbra effect
Focal spot size:microfocus: F = 3 µmnanofocus: F = 0.6 µm
M=FDD/FOD ; Vx=P/M
Introduction & Fundamentals
mikrofocus nanofocuslimiting factor for image resolution = Fdetail detectability about 1/3 F
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Resolution and Detail DetectabilityDetail detectability of the nanofocus tube
Conclusion:detail detectabilityis no measurefor sharpness
Focal Spot 2.5 µm 0.8 µm
500 nm 500 nm
5 µm 5 µm
Introduction & Fundamentals
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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
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Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
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nanotom multra-high resolutionnanoCT 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
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Principle of CT
Acquisition of
(2D) projections
whilst the object
turns through 360°
rotation steps << 1°
nanotom CT
X-ray source CNC Detector
CT / volume reconstruction
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Principle of CTAcquisition
movie
nanotom CT
Sample rotation + acquisition imagesCopyright General Electric 2014
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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
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resolution comparison
1 mm
Improved sharpness (+80%) & increased CNR (+100%) due to diamondwindow and low noise detector
State of the art nanotom m
metallic foam: material development & characterization, automotive
Contrast resolution
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resolution comparison
Improved sharpness (+80%) & increased CNR (+100%) due to diamondwindow and low noise detector
metallic foam: material development & characterization, automotive
Contrast resolution
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resolution comparison
Comparison example (metal alloy*)
CT result close to synchrotron-based CT
State of the art nanotom m
AlMg5Si7 Alloy: material research, University & Industrial metallography labs
Synchrotron-based CT (ESRF Grenoble/France)
100 µm
* J. Kastner, B. Harrer, G. Requena, O. Brunke, A comparative study of
high resolution cone beam X-ray tomography and synchrotron tomography applied to
Fe- and Al-alloys. NDT&E Int. vol. 43, pages 599-605
Copyright General Electric 2014
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Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
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Cretaceous reservoir sandstone“Bentheimer”
Standard petrophysicalanalysis
Scan data of geological samples
Bentheimer sandstone
Electron microscope images and thin sections with highly weathered feldspar (left); porosity permeability cross plot from experimental analysis (right)
38 mm
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Cretaceous reservoir sandstone“Bentheimer”
X-ray CT(Ø 5 mm)Vx = 1 µm
Scan data of geological samples
1 mm
A
BAA
BB
A
B
Bentheimer sandstone
2D slice and 3D volume of CT scan. Quartz (grey), (A) clay (brown), (B) feldspar (blue) and zirconia (red). Right: pore space is separated (green)
5 mm
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Cretaceous reservoir sandstone“Bentheimer”(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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Cretaceous reservoir sandstone“Bentheimer”(Ø 5 mm)
Vx = 1 µm
Scan data of geological samples
Comparison of sandstones
average Porosity: ~ 22.5 %representative scan volume: 1000x1000x1000 Voxel
average Porosity: ~ 7 %representative scan volume: > 1750x1750x1750 Voxel
1 mm
Bentheimer Sandstone Flechtingen Sandstone
Porosity (CT) with respect to volume size for different sandstones
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Scan data of geological samplesBentheimer sandstoneDigital Rock Evaluation
segmentation percolation testconnectivity test
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Scan data of geological samplesBentheimer sandstoneDigital Rock Evaluation
quantitative evaluationskeletonization
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Cretaceous reservoir sandstone“Bentheimer”(Ø 5 mm)
Vx = 1 µm
Avizofluid flow simulation
Scan data of geological samples
videoBentheimer sandstoneDigital Rock Evaluation
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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
3 mm
zoomedarea
Etna
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1 mm
Scan data of geological samples
Zoom into yz-slice with measurement of thin wall: 1.8 µm
3 mm
Pyroclastic rock (Ø 1 mm)
Vx = 1 µm
yz-slice
Etna
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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
3 mm
Etna
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1 mm
Scan data of geological samples
3 mm
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.
SCHEMATIC WORKFLOW FOR POROSITY AND PERMEABILITY ANALYSIS
Etna
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1 mm
Scan data of geological samples
Pyroclastic rock (fresh’11)(Ø 10 mm)
Vx = 5 µm
3D volume
The volume rendering visualizes the separated pore space, each individual pore has a separate color.
SCHEMATIC WORKFLOW FOR POROSITY AND PERMEABILITY ANALYSIS
Etna
Copyright General Electric 2014
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1 mm
Scan data of geological samples
Pyroclastic rock (fresh’11)(Ø 10 mm)Vx = 5 µmAvizofluid flow simulation
The pore space is further skeletonized. Different colors refer to different throat size.
SCHEMATIC WORKFLOW FOR POROSITY AND PERMEABILITY ANALYSIS
Etna
Copyright General Electric 2014
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1 mm
Scan data of geological samples
The color slice intersects the velocity field calculated with XLab Hydro and visualizes the vector field. Colors give the velocity’s magnitude.
pyroclastic rock (fresh’11)(Ø 10 mm)Vx = 5 µmAvizofluid flow simulation
SCHEMATIC WORKFLOW FOR POROSITY AND PERMEABILITY ANALYSIS
Etna
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Content
1. Introduction & Fundamentals
2. nanotom CT / resolution comparison
3. Scan results for geological samples
4. Conclusion & Outlook
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Conclusions• State of the art high resolution tube based X-ray CT with
the phoenix nanotom m 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
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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
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Contact and further information:
www.ge-mcs.com/en/phoenix-xray.html
www.ge-mcs.com/de/phoenix-xray/applications/geology-exploration.html