The impact of constitutive modeling of porous rocks on 2-D wellbore stability analysis

It is well established that a wellbore may fail under tension or shear compressive modes. Recently, the behavior of porous rocks has been studied, showing that they may fail because of hydrostatic compression. Cap models may represent the compacting behavior of porous rocks. This work presents a comparison among Drucker-Prager, Mohr-Coulomb, and cap model in wellbore stability analysis for a borehole drilled in 30% porosity limestone from a deep water reservoir, Campos Basin, offshore Brazil. It shows that traditional models used in wellbore stability analysis may lead to erroneous conclusions about the stability in the vicinities of the borehole.