Simulation of Viscous Fingering with the Lattice Boltzmann Method - Wetting Characteristics and Post-Breakthrough Evolution
Abstract
We apply the Rothman-Keller colour gradient Lattice Boltzmann Method to simulate two phase flow of immiscible fluids through a 2D model of a porous medium to study the modes of flow, and particularly, viscous fingering. A model of a 2D porous medium saturated with a "blue'" fluid is injected from the left with a "red'" fluid with a range of viscosity ratios from M=0.01 through M=100 and wetting angles from fully wetting to non-wetting. As expected, the viscosity ratio plays a dominant role with stable displacement of an almost linear front of red fluid when the viscosity ratio is above unity, and narrow tendrils (viscous fingering) occurring when the viscosity ratio is below unity. We find that wetting angle plays a more subtle and complicated role. One effect is that more wetting fluids exhibit different morphology of flow with more rounded fingers. The effect of wetting on saturation levels at breakthrough is - for most model realizations - a rise in saturation with wettability. However, it can be more complicated and in some cases, we have observed two optimal wetting angles that maximize saturation, which suggests the dynamics of flow has a complex relationship with the geometry of the medium and hydrodynamical parameters. This kind of behaviour potentially has immense significance to Enhanced Oil Recovery (EOR). After breakthrough, most of the flow continues through narrow fingers but these evolve and broaden so the saturation continues to increase albeit at a reduced rate. Another unexpected result is that injection of the non-wetting fluid has a higher rate of saturation increase after breakthrough which results in a higher final saturation than the case of injection with a wetting fluid. This work demonstrates that the Rothman-Keller colour gradient Lattice Boltzmann Method is a powerful method to study multiphase flow and can be used to uncover unexpected behaviour and phenomena with scientific and practical significance.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMNG0080015M
- Keywords:
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- 4415 Cascades;
- NONLINEAR GEOPHYSICS;
- 4568 Turbulence;
- diffusion;
- and mixing processes;
- OCEANOGRAPHY: PHYSICAL;
- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS