Downhole shock absorber for torsional and axial loads

Abstract

A shock-absorber subassembly for a subsurface drilling assembly is disclosed. The shock-absorber subassembly comprises a mandrel, a body assembly, and at least one torsional spring assembly. The mandrel has a bore extending therethrough and has one end connectable to a portion of the subsurface drilling assembly. The body assembly has a bore extending therethrough and one end connectable to another portion of the subsurface drilling assembly. The body assembly is coupled to the mandrel to establish fluid communication between the bore of the mandrel and the bore of the body assembly and to permit planar rotational movement of the mandrel relative to the body assembly. The at least one torsional spring assembly engages the mandrel and the body assembly to absorb torsional shocks and vibrations between the mandrel and the body assembly and to limit the degree of planar rotation between the mandrel and the body assembly. In a second embodiment, the body assembly is coupled to the mandrel to permit axial movement as well as planar rotational movement. In this second embodiment, the shock-absorber subassembly further comprises at least one axial spring assembly engaging the mandrel and the body assembly to absorb axial shocks and vibrations between the mandrel and the body assembly.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to a vibration-dampening and shock-absorbing device, and more particularly, but not by way of limitation, to a shock-absorber subassembly adapted to engage a subsurface drilling assembly above the drill bit, the shock-absorber subassembly provided with at least one resilient shock absorber for absorbing torsional vibrations, shocks, and impact loads to prevent and reduce wear on drilling components.[0003]2. Brief Description of Related Art[0004]During the drilling of an oil or gas well, a drill string is rotated from the surface causing a drill bit to cut and crush rock formations with the weight of drill collars assisting in driving the drill bit downward into contact with the underlying rock. Drill collars also act as conduits for the drilling fluids or “mud” used to lubricate the drill bit and carry cuttings back to the surface. Mud motors and turbines are sometimes employed do...

AI Technical Summary

Problems solved by technology

In drilling through such formations, the drill bit may generate significant vibrations, shocks, and impact loads.

If transmitted to the drill string, the vibrations, shocks, and impact loads will eventually cause metal fatigue which could result in cracking and ultimate failure of joints between drill string segments, as well as entire drill string components.

The direct transfer of these loads from the drill bit to the drill string reduces the useful life of the drill bit.

Additionally, the efficiency may be reduced because the shocks and impact loads may cause the drill bit to “jump” or lose contact with the surface being drilled.

Vibrations, shocks, and impact loads may also have an adverse affect on sensors and electronics located within the drill string.

While such sensors provide highly

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