Shock absorbers

The shock absorber is a tool capable of transmitting the rotary torque necessary to the bit, and also capable of absorbing vibrations that may be initiated by the bit as it repeatedly penetrates the rock. These vibrations are transmitted through the drill string where they may create fatigue in the tool joints. Further, by keeping the bit on the bottom the shock absorber increases penetration rate. The tool consists of a mandrel assembly sliding inside a body assembly. Torque is transmitted through the drive ribs of the mandrel sliding in longitudinal grooves in the lower part of body assembly. A special spring column eliminates the longitudinal vibrations working in a chamber filled with oil. Within normal drilling parameters, the tool is not limited respectively to string weight, torque, pump rate or pressure. The minimum weight on the bit required for optimum shock absorbing effect depends on pressure drop across the bit.

Run in possibilities:
between reamers and / or stabilizers,
or directly above the bit