Abstract Throughout the initial phase of development on the Mungo field in the Central North Sea, wellbore instability and mud losses have caused serious drilling problems and additional expense. Geomechanical modeling around the salt diapir led to refinement of some drilling procedures but the direct cause of the drilling problems still remained poorly understood. A detailed fault mapping study has been carried out from the Paleocene reservoir interval through the overburden. Wellbore instability and mud loss zones displayed along the wellbores were integrated with the 3D fault model and demonstrated that the wellbore instability and mud loss incidents coincide with the location of seismically resolved faults. However, not all faults in the overburden or reservoir were associated with drilling problems. It was found that the intersection angle between the wellbore and the fault surface is critical to determine whether drilling through the fault will induce instability. The Mungo data indicates that small intersection angles (commonly between 0–45°) resulted in drilling problems while larger intersection angles (commonly between 45–90°) were not associated with drilling problems. These results have been incorporated into the current well planning and drilling strategy for Mungo development wells. So far, a sidetrack well and chalk oil appraisal well has been successfully drilled in the overburden. Potential problem zones predicted in advance were mitigated for in the well planning stage and contingencies included in the drilling budget. The overburden drilling risks are understood by visualizing the integrated geology and drilling data in 3D, so it now takes less time, and therefore less cost to drill successfully to the reservoir target. The techniques are also being applied successfully for well planning and drilling on other fields.