When a well is drilled, the equilibrium in-situ stress is changed. In order to support the stress relief induced by the drilling and to prevent hydrocarbon influx into the cavity, the borehole is filled with a fluid. These ...

Wellbore instabilities are responsible for 10-20% of the total drilling cost. It has been estimated that wellbore instability causes an annual economic loss of US$ 500 - 1000 million in the oil industry across the world. ...