Departmental Seminar

Lattice-Boltzmann Modelling of Immiscible Fluid Displacement in Complex Porous Media

Mr Zhe (Rex) Li
PhD Candidate, Department of Applied Mathematics

Over the past two decades, multicomponent lattice-Boltzmann (LB) modelling has become a popular numerical technique to study the porous medium systems. For this technique to become a practical computational platform at a production level and to solve realistic problems that can be readily incorporated in the digital core analysis services for the oil and gas industry, there are still some challenges to resolve. My project intends to resolve some of issues confronted by the LB community.

The first part of my talk investigates the impact on LB modelling of the fundamental trade-off between image resolution and field of view. This is of practical value since 3D images of geological samples rarely have both sufficient resolution to capture fine structure and sufficient field of view to capture a full representative elementary volume of the medium. Based on the study, we provide guidance for experimental data collection and how to apply the LBM to accurately resolve physics of interest for two-fluid flow in porous media. Resolution effects are particularly relevant to the study of low-porosity systems, including fractured materials, when the typical pore width may only be a few voxels across.

The second part of my talk presents the exploration of the two-fluid displacement mechanism, especially the Haines jump and associated snap-off dynamics during drainage, by using an alternative flux boundary condition, which is numerically more stable, and can more realistically mimic experiments to simulate fluid flow at a prescribed capillary number. Irreversible events such as Haines jump in multiphase flow is what ultimately determines the hysteric behaviour of the porous medium systems. The high temporal resolution feature of LB technique makes it a suitable candidate to capture the dynamics of fast events (e.g. Haines jump in millisecond). We study the impacts of both geometries of the porous medium using persistent homology and dynamic factors of the fluids (i.e. viscosity ratio and capillary number) on the occurrence and frequency of snap-off events during drainage.

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