Abstract: Wellbore instability problems have been attributed mainly to rock-fluid interaction, especially when drilling shaley formations with water-base fluids. However, recent studies showed that other events during drilling may contribute much more decisively in causing the problems than the rock-fluid interaction and swelling. The Study presents a conceptual model to analyze wellbore stability based on energy. The Drill string vibration concern as an important problem and is fairly complex since it is generally a combination of longitudinal, torsional and transverse modes, which are all present and coupled. Because of the complexity and the importance of Drill string vibrations in the drilling operation, a full simulation covering all the relevant phenomena is not practical and a common approach has been used to study the vibration mechanisms individually. The consideration was subjected to the effect of the longitudinal and torsional vibration