M Aslannejad - Department of Chemical and Petroleum Engineering, Persian Gulf University, Bushehr, Iran
A Khaksar Manshad - Department of Chemical and Petroleum Engineering, Persian Gulf University, Bushehr, Iran
H Jalalifar - Department of Chemical and Petroleum Engineering, Shahid Bahonar University, Kerman, Iran
A Fazeli - Department of Chemical and Petroleum Engineering, Persian Gulf University, Bushehr, Iran

Geomechanical stability can have a significant role in the development of deep wells. Wellbore failure, loss circulation and sand production are costly problems for oil industries that can be mitigated by devising a sensible plan through choosing a suitable rock failure criterion. This paper describes comparison of four different rock failure criteria named Tresca, Mohr-Coulomb, Mogi-Coulomb, and Modified Lade based on triaxial and polyaxial test data of two different rock strength data to determine a proper criterion in order to be used for wellbore stability analyses. This makes it possible to reduce drilling costs by designing wells properly enough to minimize borehole problems without excessive cost. A further benefit of considering a suitable failure criterion is that, the optimum mud weight and well direction predicted by them can be much closer to reality

Wellbore stability, Rock failure criteria, Drilling, Polyaxial test data