Fully Coupled Plastic-Softening Porosity-Based THM Model of Supercharged Zone Evolution around the Wellbore with Dynamic Mud Cake Growth

Farahi A. Mortazavi A. Salarirad H.
2026 Springer

Rock Mechanics and Rock Engineering
2026

Accurate prediction of the supercharged zone during Overbalanced Drilling (OBD) operation requires an understanding of the complex interplay between Thermo-Hydro-Mechanical (THM) coupling, plastic deformation with strength softening, and dynamic mud cake growth. While the impact of these factors on the evolution of the supercharged zone has been examined in isolation, their synergistic effects and the temporal variation in the dominance of pore pressure localization mechanism remain unquantified. This study introduces a novel, fully coupled Plastic-Softening-Porosity-Based (PSPB) THM model to bridge this gap. The model is validated against analytical solutions. Numerical simulations reveal a clear temporal evolution: the pore pressure response transitions through three distinct stages. The early-time response is dominated by plasticity and THM coupling—which drive the spatio-temporal evolution of reservoir properties (e.g., porosity, permeability, thermal conductivity, and specific heat capacity)—before a paradigm shift occurs, establishing mud cake dynamics as the long-term controlling factor. Furthermore, a sensitivity analysis establishes a definitive hierarchy of influence on pore pressure localization, ranking in-situ stress anisotropy and wellbore pressure as most critical, followed by reservoir permeability and thermal gradients. These findings provide a framework that emphasizes the critical need to integrate mud cake dynamics with coupled geomechanics for accurate assessment of formation damage and pore pressure prediction.

Dynamic mud cake , Fully coupled THM , OBD operations , Strength softening , Supercharged zone

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Department of Mining Engineering, Amirkabir University of Technology, Tehran, Iran
School of Mining and Geosciences, Nazarbayev University, 53 Kabanbay Batyr Ave., Astana, Kazakhstan

Department of Mining Engineering
School of Mining and Geosciences

10 лет помогаем публиковать статьи Международный издатель

Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026