Event-based contact angle measurements inside porous media using time-resolved micro-computed tomography

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.jcis.2020.03.099.

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Authors

Arjen Mascini , Veerle Cnudde, Tom Bultreys 

Abstract

Hypothesis
Capillary-dominated multiphase flow in porous materials is strongly affected by the pore walls’ wettability. Recent micro-computed tomography (mCT) studies found unexpectedly wide contact angle distributions measured on static fluid distributions inside the pores. We hypothesize that analysis on time-resolved mCT data of fluid invasion events may be more directly relevant to the fluid dynamics.
Experiment
We approximated receding contact angles locally in time and space on time-resolved mCT datasets of drainage in a glass bead pack and a limestone. Whenever a meniscus suddenly entered one or more pores, geometric and thermodynamically consistent contact angles in the surrounding pores were measured in the time step just prior to the displacement event. We introduced a new force-based contact angle, defined to recover the measured capillary pressure in the invaded pore throat prior to interface movement.
Findings
Unlike the classical method, the new geometric and force-based contact angles followed plausible, narrower distributions and were mutually consistent. We were unable to obtain credible results with the thermodynamically consistent method, likely because of sensitivity to common imaging artifacts and neglecting dissipation. Time-resolved mCT analysis can yield a more appropriate wettability characterization for pore scale models, despite the need to further reduce image analysis uncertainties.

DOI

https://doi.org/10.31223/osf.io/p5e7n

Subjects

Earth Sciences, Fluid Dynamics, Hydrology, Physical Sciences and Mathematics, Physics

Keywords

multiphase flow, porous media, contact angle, wettability, Haines jump, imaging, interfacial curvature, mCT, Pore-scale, Primary drainage, X-ray micro-tomography

Dates

Published: 2020-01-28 09:13

Last Updated: 2020-04-02 13:12

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License

CC BY Attribution 4.0 International

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