565—51.9 (458A) Deviation. No well may be intentionally directionally deviated from the vertical without the written approval of the department. Deviation is permitted without special permission for short distances, to straighten the hole, sidetrack junk, or correct other mechanical difficulties. The maximum point at which a well penetrates the producing formation shall not vary unreasonably from the vertical drawn from the center of the hole at the surface. Directional surveys may be required by the department whenever the location of the bottom of the well is in doubt. When necessary to protect correlative rights, the department shall require that the well be straightened.