Laboratory and numerical discontinuum modeling of wellbore stability

Wellbore-stability analyses based on intact wellbore walls can be too conservative because failed/fractured zones around wellbores relieve stress and give support. Wellbore-breakout analyses indicate that most drilled wells experience deformation beyond the rupture stage and that this deformation is acceptable for the drilling process. Validation of the methods available to predict wellbore stability requires a comparison of theoretical models with experimental simulations of wellbore behavior. This paper describes a series of scaled laboratory wellbore-stability experiments carried out under various borehole inclinations and stress conditions