A 3D surface of an area of the full-field unstructured grid simulation showing horizontal wells and faults. Three large fault surfaces are clearly visible, which appear as tears on the 3D surface. Grid cells adjacent to the faults conform to the geometry of the faults. Well perforated grid cells are highlighted above the 3D surface. The gridding method handles complex situations where complex wellbores can intersect other complex wellbores or with the faults and a fault plane can intersect with other fault planes.