SELF-ORGANIZATION DURING REACTIVE FLUID-FLOW IN A POROUS-MEDIUM

When a reactive fluid circulates inside a porous medium it can dissolv e some minerals if equilibrium is not reached and modiy the porosity a nd permeability. The positive feedback between fluid transport and min eral dissolution read to complex reaction front morphologies such as f ingers. Our study is carried out with two objectives: 1) to evaluate e xperimentally these processes at a decimeter scale, 2) to compare the experiment to a numerical model of water-rock interaction. The experim ent consists of a two-dimensional porous medium that allows for the di ssolution of halite under an imposed fluid flow. The numerical code us ed solves the equations of reaction and transport in a porous medium. Both experiment and numerical simulation indicate the development of a n instability whose propagation rate depends on the rate of water inje ction raised to a 2/3 power.