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| Titel |
Sensitivity study of an image processing workflow on synchrotron μ-CT images of Berea sandstone |
| VerfasserIn |
Leon Leu, Steffen Berg, Holger Ott, Ryan T. Armstrong, Frieder Enzmann, Michael Kersten |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094993
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| Publikation (Nr.) |
 EGU/EGU2014-10431.pdf |
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| Zusammenfassung |
| For the present study, the sensitivity of the threshold value for watershed-based segmentation
and global threshold segmentation was assessed on μ-CT images of fine grained Berea
sandstone. The sensitivities were assessed in terms of porosity, permeability, single-phase
flow simulations and capillary pressure curves that were calculated from the segmented data.
The μ-CT images of fine grained Berea sandstone with a resolution of 3 μm/pixel was
segmented using different threshold values that were systematically varied, which
resulted in slightly different structures for the pore space. The results show, that
watershed-based segmentation is more robust than global threshold segmentation and that the
measured permeability showed a stronger sensitivity to threshold variation than
porosity, indicating that it is a more sensitive parameter to image segmentation
settings.
Calculated permeability and capillary pressure curves matched well with experimental
data revealing that the average pores and pore throats of the watershed-based segmented
structure were segmented accurately. In contrast, capillary pressure curves indicated that pore
sizes near the resolution limit of 3 μm, located in kaolinite rich areas of the rock, were not
segmented correctly and thus caused the disagreement between the experimental measured
porosity and that measured from the digital rock image. We conclude that capillary pressure
curves and permeability values that result from the digital rock data is more indicative of the
flow relevant fraction of the pore structure and are therefore better suited as validation
criterion than porosity data.
Numerical modeling of two-phase flow on segmented data from high resolution μ-CT
images enhances our understanding of the dynamics of multiphase-flow of immiscible fluids
at the pore-scale. To be confident about simulated data it is therefore important to identify
meaningful properties, e.g. permeability, that can be used as benchmark parameters for
testing the quality of segmented data. |
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