Plasticity and strain localization around a horizontal wellbore drilled through a porous rock formation

Predicting plastic deformation and localization band around a wellbore drilled through a porous rock is a challenging task that could have important implications for the prediction of instability and sand production. This study focuses on analyzing stress field, plastic zones, and localized deformations around a horizontal borehole drilled at a great depth through a highly porous rock formation. Several laboratory studies demonstrate that, depending on the loading path, highly porous rocks are susceptible to different failure mechanisms, but most of these mechanisms are mainly due to shear-induced dilation and shear-enhanced compaction. Plasticity models, in conjunction with bifurcation analysis, represent an extremely useful framework for describing such detailed constitutive responses. This paper presents a new elastoplastic constitutive model characterized by two yield surfaces intersecting smoothly, that is able to capture the different failure modes. The model is validated against...