Geomechanical Unload‐Reload Response of Cylindrical Cavities for Wellbore Stability

ABSTRACT Subsurface exploration typically requires application of cycles of fluid pressures on the surface of the cylindrical cavity during wellbore circulation. In this study, a numerical model is proposed that can capture the evolution of the elastic‐plastic boundary and the shear‐induced porosity/ stiffness changes during the cycles of cavity contraction and expansion. The developed solver is benchmarked against the existing experimental data and other numerical solutions. During pressure‐induced unloading and reloading of the cavity, increments are chosen so that the model satisfies the equilibrium conditions. When the stress state is reduced from the in situ stress to zero stress at the cavity boundary and then reloaded to a load ratio, it is observed that the material exhibits a stiffer, apparent elastic‐dominated response at higher load ratios. Additionally, when the porosity is updated for each material point, the maximum radial displacement during unloading increases by nearly 20%, and the recovered stress after reloading decreases by approximately 15% compared to the case of constant porosity. Parametric studies on dimensionless factors further reveal that higher (effect of shear modulus) and (effect of pre‐consolidation pressure) values lead to narrower hysteresis loops, indicating that the medium reaches an elastic‐dominated response more rapidly. Quantitatively, increasing from 25.82 to 60.26 (with ) reduces the final specific energy by nearly 70%, while increasing from 1.25 to 2.00 (with ) results in a 30% reduction in energy dissipation.