REACTIVE TRANSPORT: EXPERIMENTS AND PORE-NETWORK MODELLING

摘要

Dissolution and deposition phenomena are key issues in the CO2 geological storage.In the past few years,it has been proven that CO2 injection can lead to important pore structure modifications which mainly depend on the thermodynamic conditions,the rock and fluid composition and the flow regime.Predicting these modifications and their impact on the reservoir permeability and porosity is crucial for the success of CO2 sequestration projects. This paper presents an experimental and numerical study to evaluate in a comprehensive manner the impact of the deposition regimes on the relationships between permeability and porosity.Experiments have been performed in glass micromodels to visualize deposition mechanisms for different regimes.A reactive transport model using the porenetwork approach has been developed to simulate the deposition phenomenon in the case of a single-phase flow.This numerical model is based on solving the macroscopic convection-diffusion equation.Its macroscopic coefficients,mean velocity,dispersion coefficient and apparent reaction term,are obtained for each unit cell of the pore network by solving analytically a set of equations describing the reactive transport at microscopic scale.The regimes that govern the deposition phenomena are numerically investigated.It is demonstrated that deposition patterns depend on both scales of the reactive transport, microscopic and macroscopic,each one being characterized by relevant dimensionless numbers.