Which term describes the drilling process where the bit rotates to cut rock?

• A. Percussive Drilling
• B. Coring
• C. Milling
• D. Rotary Drilling

Answer: (D)

Rotary drilling is the method where the bit is attached to a drill string and rotated to shear and cut through rock as the borehole advances. The rotation provides the cutting action, while drilling fluid is pumped down to cool the bit and carry rock cuttings back to the surface. This differs from percussive drilling, which relies on hammer-like impacts rather than continuous rotation; from coring, which uses a special core bit to retrieve a cylindrical rock sample; and from milling, which uses cutters to remove material for shaping or enlarging but isn’t the standard approach to steadily advance a borehole.