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.

1 . A shock-absorber subassembly for a subsurface drilling assembly, the shock-absorber subassembly comprising:
 a mandrel having a bore extending therethrough and having one end connectable to a portion of the subsurface drilling assembly;   a body assembly having a bore extending therethrough and one end connectable to another portion of the subsurface drilling assembly, the body assembly 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; and   at least one torsional spring assembly engaging 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.   
   
   
       2 . The shock-absorber subassembly of  claim 1 , wherein the torsional spring assembly comprises:
 a rigid drive key; and   at least one spring engaging the drive key.   
   
   
       3 . The shock-absorber subassembly of  claim 2 , wherein the at least one spring comprises two springs engaging the drive key and each spring opposingly-disposed on opposite sides of the drive key. 
   
   
       4 . The shock-absorber subassembly of  claim 3 , wherein each spring is a flat spring having at least one arcuate portion. 
   
   
       5 . The shock-absorber subassembly of  claim 1 , wherein an outer surface of the mandrel has at least one spring recess defined therein, and wherein an inner surface of the body assembly has at least one spring recess defined therein, the at least one spring recess of the mandrel and the at least one spring recess of the body assembly cooperating to form at least one spring chamber therebetween, the torsional spring assembly positioned in the spring chamber. 
   
   
       6 . The shock-absorber subassembly of  claim 5 , wherein the torsional spring assembly comprises:
 a rigid drive key; and   at least one spring engaging the drive key and at least one of the mandrel or the body assembly.   
   
   
       7 . The shock-absorber subassembly of  claim 6 , wherein the at least one spring comprises two springs engaging the drive key and each spring opposingly-disposed on opposite sides of the drive key. 
   
   
       8 . The shock-absorber subassembly of  claim 7 , wherein each spring is a flat spring having at least one arcuate portion. 
   
   
       9 . A shock-absorber subassembly for a subsurface drilling assembly, the shock-absorber subassembly comprising:
 a mandrel having a bore extending therethrough and having one end connectable to a portion of the subsurface drilling assembly;   a body assembly having a bore extending therethrough and one end connectable to another portion of the subsurface drilling assembly, the body assembly 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 and axial movement of the mandrel relative to the body assembly;   at least one torsional spring assembly engaging 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; and,   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.   
   
   
       10 . The shock-absorber subassembly of  claim 9 , wherein the torsional spring assembly comprises:
 a rigid drive key; and   at least one spring engaging the drive key.   
   
   
       11 . The shock-absorber subassembly of  claim 10 , wherein the at least one spring comprises two springs engaging the drive key and each spring opposingly-disposed on opposite sides of the drive key. 
   
   
       12 . The shock-absorber subassembly of  claim 11 , wherein each spring is a flat spring having at least one arcuate portion. 
   
   
       13 . The shock-absorber subassembly of  claim 12 , wherein an outer surface of the mandrel has at least one spring recess defined therein, and wherein an inner surface of the body assembly has at least one spring recess defined therein, the at least one spring recess of the mandrel and the at least one spring recess of the body assembly cooperating to form at least one spring chamber therebetween, the torsional spring assembly positioned in the spring chamber. 
   
   
       14 . The shock-absorber subassembly of  claim 13 , wherein the spring recesses in the mandrel and the body assembly have a length greater than the length of the torsional spring assembly to permit axial movement of the torsional spring assembly within the spring chamber during axial movement of the body assembly relative to the mandrel. 
   
   
       15 . The shock-absorber subassembly of  claim 14 , wherein the torsional spring assembly comprises:
 a rigid drive key; and   at least one spring engaging the drive key and at least one of the mandrel or the body assembly.   
   
   
       16 . The shock-absorber subassembly of  claim 15 , wherein the at least one spring comprises two springs engaging the drive key and each spring opposingly-disposed on opposite sides of the drive key. 
   
   
       17 . The shock-absorber subassembly of  claim 16 , wherein each spring is a flat spring having at least one arcuate portion.