Reactive flow in porous media based on numerical simulations at the pore scale
Loading...
Files
Date issued
Authors
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Reuse License
Abstract
Long-term evolution of permeability and tortuosity due to porosity changes evoked by reactivity of aqueous solutions is of paramount importance for predicting waterrock interaction. This challenge is best tackled by introducing pore-scale modeling, where the modeling domain is a highresolution tomographic image of the porous media. This thesis presents such a novel reactive fluid dynamics modelling approach combining numerical flow, transport and geochemical solvers. A voxel based Navier-Stokes-Brinkman solver in a finite volume formulation is coupled to the thermodynamic equilibrium code PhreeqC. A Lagrangian transport approach realizes the sequential simulation of advection, diffusion and reaction. Virtual particles transport aqueous solutions that equilibrate with the pore fluid. The thus changed species distributions potentially induce local disequilibria at reactive grain surfaces and initiate dissolution and precipitation reactions. The novel approach enables to couple at high spatial and temporal resolution transport with reactivity of the fluid, and the quantity of mineral alteration in the pore matrix depending on both, the local geochemical equilibrium and mineral phase reaction kinetics. The approach is realized by high-performance parallelized computations that are performed directly on the voxel grid of digital rock samples. SrSO4 precipitation is modelled with a diffusive geochemical system in a sand grain matrix. Retreat of calcite cements in a sandstone matrix due to dissolution reactions is directly visualized by digital rock physics experiments. Results highlight the necessity of considering the effect of local pore alterations on the development of system-specific transport parameters.