Mud rotary drilling is used here to create a stable wall geothermal hole. This Geothermal drilling rig model GT635 Rig is equipped with top rotary drive unit which provides torque capacity 6000 LBF-ft / 3000 psig - 8135 Nm / 209.9 bar and Rotation speed 0-80 rpm. It also provides automatic constant rotation power control. The hydraulic motor that travels up and down the mast supplies torque directly to the drill pipe. The drill bit, a tricone roller, is rotated by the drill pipe. Drilling mud is circulated down the drill pipe and out openings in the bit where it cleans cuttings from beneath the bit, cools the bit and carries cuttings to the surface where they are separated from the fluid.