An improved method for estimating capillary pressure from 3D microtomography images and its application to the study of disconnected nonwetting phase. (April 2018)

• Record Type: Journal Article
• Authors: Li, Tianyi; Schlüter, Steffen; Dragila, Maria Ines; Wildenschild, Dorthe
• Is Part Of: Advances in water resources. Volume 114(2018)
• Page Start: 249
• Page End: 260
• Publication Date: 2018-04
• Subjects: Multiphase flow -- Porous media -- Computed microtomography -- Curvature -- Capillary pressure measurement; Hydrology -- Periodicals; Hydrodynamics -- Periodicals; Hydraulic engineering -- Periodicals; 551.48
• DOI: 10.1016/j.advwatres.2018.02.012
• Languages: English
• ISSNs: 0309-1708

Abstract

Highlights: Improved estimates of interfacial curvature significantly advances the potential to unravel phenomena associated with multi-phase flow. The approach combines selective interface modification and distance weighting approaches and is verified against synthetic and real data. We demonstrate significant improvement over previous methods. Pressure of disconnected, non-wetting phase is controlled more by pore geometry, and less by bulk liquid phase behavior. Abstract: We present an improved method for estimating interfacial curvatures from x-ray computed microtomography (CMT) data that significantly advances the potential for this tool to unravel the mechanisms and phenomena associated with multi-phase fluid motion in porous media. CMT data, used to analyze the spatial distribution and capillary pressure–saturation ( Pc – S ) relationships of liquid phases, requires accurate estimates of interfacial curvature. Our improved method for curvature estimation combines selective interface modification and distance weighting approaches. It was verified against synthetic (analytical computer-generated) and real image data sets, demonstrating a vast improvement over previous methods. Using this new tool on a previously published data set (multiphase flow) yielded important new insights regarding the pressure state of the disconnected nonwetting phase during drainage and imbibition. The trapped and disconnected non-wetting phase delimits its own hysteretic Pc – S curve that inhabits the space within the main hysteretic Pc – S loop of the connected wetting phase. Data suggests that the pressure of the disconnected, non-wetting phase is strongly modified by the pore geometry rather than solely by the bulk liquid phase that surrounds it.