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Wettability-driven pore-filling instabilities: Microfluidic and numerical insights
Lifei Yan1, Johannes C Müller2, Tycho L van Noorden3
1Department of Earth Sciences, Utrecht University, Princetonlaan 8a, Utrecht, 3584 CB, Netherlands; Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, Delft, 2628 CN, Netherlands.
Journal of Colloid and Interface Science
|May 21, 2025
Summary
Wettability significantly impacts fluid flow in porous media, especially at low flow rates, influencing interface stability and pressure dynamics. This research clarifies wettability
Area of Science:
- Multiphase flow in porous media
- Interface dynamics and stability
- Surface wettability effects
Background:
- Interface dynamics, like Haines jumps, are vital for understanding multiphase flow in porous media.
- The precise role of intrinsic surface wettability in pore-filling events and the resulting pressure responses are not fully understood.
- Further investigation is needed to clarify how wettability influences interface stability and pressure dynamics during fluid displacement.
Purpose of the Study:
- To evaluate the impact of intrinsic surface wettability on interface stability during pore-filling events.
- To investigate the pressure dynamics associated with wettability variations in porous media.
- To provide critical insights for improving pore-network models and understanding wettability effects.
Main Methods:
- Microfluidic experiments were conducted using a PDMS micro-model with controlled wettability (contact angles of 60°, 95°, and 120°).
- Two-phase flow simulations using the level-set method were performed to model water displacing air or Fluorinert.
- Experiments covered capillary- to viscous-dominated flow regimes across three injection velocities, with high-resolution imaging and synchronized pressure recordings.
Main Results:
- At low capillary numbers, wettability significantly influenced burst pressure and interface pinning, with its effect diminishing at higher capillary numbers.
- An apparent wettability shift was observed due to hysteresis, and a capillary pressure barrier was identified, linked to pore-wall slope variations.
- Simulations successfully replicated experimental trends, confirming the crucial role of wettability in pore-scale displacement phenomena.
Conclusions:
- Intrinsic surface wettability plays a critical role in dictating interface stability and pressure dynamics, particularly under low capillary number conditions.
- The study highlights the complex interplay between wettability, flow regime, and pore geometry in multiphase flow.
- Findings offer valuable data for refining pore-network models and enhancing the understanding of wettability in diverse porous media applications.
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