Linking continuum-scale state of wetting to pore-scale contact angles in porous media
| Autor: | Chenhao Sun, Steffen Berg, A. L. Herring, James E. McClure, Mehdi Shabaninejad, Ryan T. Armstrong, Peyman Mostaghimi |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Capillary pressure
Materials science Capillary action 0208 environmental biotechnology Lattice Boltzmann methods FOS: Physical sciences 02 engineering and technology Condensed Matter - Soft Condensed Matter Physics::Geophysics Physics::Fluid Dynamics Biomaterials Contact angle Colloid and Surface Chemistry Multiphase flow Fluid Dynamics (physics.flu-dyn) Mechanics Physics - Fluid Dynamics 021001 nanoscience & nanotechnology 020801 environmental engineering Surfaces Coatings and Films Electronic Optical and Magnetic Materials Soft Condensed Matter (cond-mat.soft) Wetting 0210 nano-technology Porous medium Relative permeability |
| Popis: | Wetting phenomena play a key role in flows through porous media. Relative permeability and capillary pressure-saturation functions show a high sensitivity to wettability, which has different definitions at the continuum- and pore-scale. At the continuum-scale, the state of wetting is defined as Amott-Harvey or USBM (United States Bureau of Mines) by capillary pressure drainage and imbibition cycles. At the pore-scale, the concept of contact angle is used, which until recently was not experimentally possible to determine within an opaque porous medium. Recent progress on measurements of pore-scale contact angles by X-ray computed micro-tomography has therefore attracted significant attention in various research communities. In this work, the Gauss-Bonnet theorem is applied to provide a direct link between capillary pressure saturation $P_c(S_w)$ data and measured distributions of pore-scale contact angles. We propose that the wetting state of a porous medium can be described in terms of geometrical arguments that constrain the morphological state of immiscible fluids. The constraint describes the range of possible contact angles and interfacial curvatures that can exist for a given system. We present measurements in a tested sandstone for which the USBM index, $P_c(S_w)$, and pore-scale contact angles are measured. Additional studies are also performed using two-phase Lattice Boltzmann simulations to test a wider range of wetting conditions. We show that mean pore-scale contact angle measurements can be predicted from petrophysical data within a few differences. This provides a general framework on how continuum-scale data can be used to describe the geometrical state of fluids within porous media. 8 pages, 6 figures |
| Databáze: | OpenAIRE |
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