Drilling Mud Drilling mud is used to lubricate the drill bit and transport drill cuttings to the surface. Drill cuttings are broken bits of solid material that are produced as the drill bit breaks the rock. As it circulates up from the drill bit, the drilling mud carries drill cuttings up to the surface, where the mud and the cuttings are separated. Drilling muds have been used to improve drilling operations for much of modern history. Water was used to soften surface material and to remove clip