Wellbore stability problems make up huge over-costs worldwide. In recent years declining resource volumes and favorable oil prices are encouraging operators to drill deeper, and more complex well trajectories drilling for hydrocarbons have turned into a much more challenging task. Furthermore, the complexity and variations of those wells have added the weight to planning and problem anticipation at both drilling and production stages. This study describes the geomechanical wellbore stability analysis of different formations drilled in Adiyaman region, Turkey. The analysis assumes validity of linear elastic theory for porous media and requires drilling reports, well logs, laboratory tests and core analysis. It was observed that with the assessment of geomechanical wellbore stability analysis mud weight window, which includes minimum mud weight and maximum mud weight, can be determined for the studied formations.