Modeling of reactive flow in deformable porous media

Micro/Macro Model for Permeability and Retention Properties of Rock Subjected to Deformation and Damage

This work aims to study the influence of cracking on porous rock Pore Size Distribution (PSD) and permeability. It is proposed to update microscopic PSD parameters with macroscopic deformation and damage. Permeability is related to pores and cracks volume fractions, which are computed from the updated PSD curves. Contrary to classical PSD integration techniques, the model handles the transition from one to two porosity modes, as illustrated schematicaly in the figure below. The proposed approach accounts for varying states of damage, as opposed to classical fracture network models. The main advantages of the proposed framework are simplicity and versatility. The input parameters are easy to determine in the laboratory, and the permeability model can supplement any damage model based on Continuum Damage Mechanics. Numerical simulations show that the model reproduces large pore shrinkage during elastic compression and captures the variations of damaged permeability for different confining pressures. The framework has been extended to unsaturated conditions. The micro/macro permeability model provides a sound basis to study hydro-chemo-mechanical rock microstructure changes in problems related to carbon dioxide sequestration.

Pictures: Arson and Pereira, 2013; Pereira and Arson, 2013

Micro/Macro Model of Permeability and Stiffness for Rocks subjected to Chemo-Mechanical Damage and Healing

This work aims to understand the microscopic damage and healing processes that cause stiffness and permeability changes in rocks subjected to chemo-mechanical perturbations. The continuum model is based on principles of poromechanics and Continuum Damage Mechanics. A continuum model is proposed to predict porosity, permeability and pressure changes upon mechanical loading and diffusion-controlled healing in drained and undrained conditions. In the first figure below, damage propagates in a Representative Volume Element of rock during loading (OA), healing occurs (BB') after unloading (AB), and the partially healed sample behaves elastically during reloading (BC). A micro model was proposed to track the evolution of the Pore Size Distribution (PSD) and permeability of carbonates subjected to mechanical loading and chemical dissolution. The second figure below shows the enlargement of pores with the quantity of carbon dioxide injected, and the resulting evolution of the PSD.

Pictures: Fleury, 2015

Pictures: Roze, 2015