Majid Sajjadian - National Iranian Oil Company, Exploration Directorate, Drilling office,
Bahman Pirmoradian - National Iranian Oil Company, Exploration Directorate, Drilling office, chemical section manager

Wellbore stability can have a major effect on well design. Traditional drilling engineering envisions the pressure window between pore pressure and fracture gradient. However, wellbore stability can control both the lower and upper bounds of the mud weight window. The pressure controlling excessive formation breakout can exceed one to control formation fluids and may be the most significant design parameter in choosing mud weight and operational practices. In addition, the maximum mud weight is often controlled by formations with micro fractures that destabilize at a lower mud weight then what is required for hydraulic fracturing resulting in excessive fluid losses. The benefits of considering wellbore stability follow not only from pre-drill planning, but real-time monitoring, updating and calibration of the living model. This paper will present examples of how wellbore stability parameters were used in well design, including casing seat selection and benefits of verifying actual wellbore stability while drilling

Geomechanics, Well Design, Wellbore Stability.