Development of an Adaptive Mesh Refinement Strategy for a Novel Immiscible Fracture Flow Model

Abstract:

Our ability to model immiscible fluid flow through fractures is limited in comparison to flow through three-dimensional porous matrices. While it is possible for multiple percolating flow pathways to exist in three dimensions; in two-dimensions, the flow networks must continuously rearrange and reconnect for simultaneous multiphase flows to occur. As this behaviour is difficult to track in experimental studies, numerical models are needed to track and quantify this continual restructuring of the flow paths.

In this presentation, we describe the development of a new numerical model to track multiphase flows in fracture networks. The model builds on a previous approach that employed a novel interface tracking strategy adapted from lattice-Boltzmann simulations, by introducing a novel Adaptive Mesh Refinement strategy to model immiscible two-phase flow in fractures. Here, we discuss the implementation of the grid-refinement strategy, discussing how the rules between the model parameters and the refinement scale were determined and implemented in the model. The accuracy of the model is shown through a series of simulations in which its output is compared to known analytical solutions. The model confirmed its robustness by successfully predicting the pressure profiles of the system for different values of wetting angle, interfacial tension, fracture aperture, and droplet radius. Results from the simulations show excellent agreement between the model and the analytical solution for both refined and unrefined cases.