Sigra can model the effects of effective stress on borehole stability. This can be used to determine whether a borehole will fail during drilling or production. It may also be used in the interpretation of the stress field from borehole breakout information.
The level of model that Sigra can use for this purpose varies from a straightforward analytical model of stress around a circular opening in an elastic media, to that taking full account of the stress strain characteristics of the formation into the post elastic range. In practice the latter model is seldom justified.