Advances in Computed Tomography for Geomaterials: GeoX 2010

Segmentation of Low-contrast Three-phase X-ray Computed Tomography Images of Porous Media

P. Bhattad¹ — C. S. Willson² — K. E. Thompson³

¹ Louisiana State UniversityDepartment of Chemical EngineeringBaton Rouge, LA 70803¹ [e-mail], ³ [e-mail]

 

² Louisiana State UniversityDepartment of Civil and Environmental EngineeringBaton Rouge, LA [e-mail]

ABSTRACT. X-Ray Computed Tomography (XCT) is an important tool to study porous-media microstructure and fluids present within the void space. In the presence of multiple fluid phases (e.g. air-water in soil science or oil-water-gas in petroleum engineering), the contrast between the fluid phases becomes important for accurate image segmentation. In some cases (e.g. a white light source or low flux), it is not possible to illuminate one of the fluid phases. The result is then a single image containing multiple phases that may contain overlapping peaks of the fluid phases due to little difference in the absorption coefficients. Building upon work done in medical-image-processing research, we have adopted a nonlinear anisotropic diffusion technique to remove noise from the XCT image that also leads to improved peak separation in the image histogram. The noise-free image is the then segmented using indicator kriging and the results are compared with segmentation results obtained using absorption-edge imaging.

 

KEYWORDS: porous media, segmentation, three phase, anisotropic diffusion, indicator kriging

1. Introduction ...