Thermo-Hydro-Mechanical Behavior of Saturated Porous Media Under Non-Isothermal Flow With Fine Particle Migration

Abstract

Clogging of reservoir formations, known as permeability damage, and wellbore clogging due to mobilization and straining of in situ fine particles are critical challenges in enhanced geothermal systems. This study presents a novel fully coupled thermo-poro-elastic model to predict the thermo-hydro-mechanical (THM) response of saturated porous media containing fine particles during fluid injection and production operations. The model incorporates transient state fluid flow to capture the coupled effects of pore pressure, temperature changes, stress variations, and fines migration. Fine particles are considered monolayered and size-distributed, and the concentration of attached fines on the solid skeleton follows the modified particle detachment model. A finite element framework is developed to simulate the reservoir response, incorporating the fine migration effects, with a new expression for well impedance accounting for transient-state fluid flow. Results reveal that the permeability damage zone surrounding the wellbore expands over time, reducing minimum permeability to 13% of its original value after only 5h. Fine migration significantly alters pore pressure and effective stresses, leading to increased well impedance. Temperature variations influence pore pressure distribution and well impedance evolution through two mechanisms: altering fluid viscosity and inducing solid skeleton deformation, and triggering fines migration and associated permeability damage. These findings provide critical insights into reservoir behavior and strategies for optimizing geothermal energy production.