Novel Modeling of Non-Isothermal Flow-Induced Fine Particle Migration in Porous Media Based on the Derjaguin-Landau-Verwey-Overbeek Theory

Abstract

Mobilization of in situ fine particles in geothermal reservoirs is a key contributor to permeability damage and clogging of the reservoir rock, leading to a decline in well productivity during enhanced geothermal operations. This phenomenon is a result of disturbance in the mechanical equilibrium of the forces acting on a given fine particle, most significant of which are electrostatic and drag forces. These forces are affected by changes in fluid flow velocities, in situ temperatures, or ionic strength of in situ fluids. Theoretical formulation of migration of fine particles in porous media driven by non-isothermal flow remains challenging, and requires a considerable number of parameters to quantify the characteristics of a given colloidal particle-pore fluid–solid grain system. The identification of all the involved parameters often necessitates costly, intricate, and time-consuming physical experiments. Moreover, implementing the complete form of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, commonly adopted to evaluate changes in electrostatic forces, is complicated, computationally demanding, and impractical, particularly when applied to evaluate fines migration at a reservoir scale. This study presents a theoretical framework for accurate and practical prediction of fine particle migration driven by non-isothermal flow in a clay-NaCl-quartz system. The novel contributions of this study are twofold. Firstly, a new numerical model is developed based on the complete DLVO theory, which integrates for the first time the effects of both thermal and hydraulic loads on all underlying parameters including both the static dielectric constant and the refractive index of the pore fluid. Secondly, an innovative simplified DLVO-based model has been introduced, requiring notably fewer parameters compared to existing models, thus offering a practical and efficient solution. The proposed models are utilized to conduct a comprehensive assessment of the fundamental mechanisms involved in fine particle liberation. Findings are key to predict fines-migration-induced permeability damage in geothermal reservoirs to achieve a sustainable design of energy storage/production operations as well as to develop effective strategies to prevent or mitigate the decline in well productivity in time.