Drill bit rotation

Regardless of bit type, it must be rotated in order to drill the rock. There are three methods used to turn the bit downhole: 1. The drillstring and bit are turned by a rotary table and kelly. 2. The drillstring and bit are rotated by a “top-drive” motor. 3. Only the bit is rotated by a hydraulic mud motor in the drillstring. (The drillstring can be held still or rotated while using a mud motor, as desired.)