Mud motor force absorption tools

Abstract

A force absorbing tool is attached to a mud motor in a drilling string. The tool includes an outer housing portion that is secured to a drilling string, and an inner mandrel portion that is secured to a mud motor and is moveable axially and rotationally with respect to the outer housing portion between an axially compressed position and an axially extended position. Helical grooves are inscribed on the inner mandrel portion, and a plurality of guide pins are associated with the outer housing and disposed within the helical groove. A compressive spring member to urge the inner mandrel portion toward the axially extended position.

1 . A force absorbing tool for attachment to a mud motor in a drilling string, comprising: 
 an outer housing portion that is secured to a drilling string;    an inner mandrel portion that is secured to a mud motor;    the inner mandrel portion being moveable axially and rotationally with respect to the outer housing portion between an axially compressed position and an axially extended position;    a helical groove inscribed on the inner mandrel portion;    a plurality of guide pins associated with the outer housing and disposed within the helical groove; and    a compressive spring member to urge the inner mandrel portion toward the axially extended position.    
   
   
       2 . The tool of  claim 1  further comprising a thrust bearing.  
   
   
       3 . The tool of  claim 1  wherein the guide pins each present a rounded inner contact surface contacting the helical groove.  
   
   
       4 . The tool of  claim 3  wherein the inner contact surface is hemispherical.  
   
   
       5 . The tool of  claim 1  wherein the pins are arranged in a helical pattern to match the helical groove.  
   
   
       6 . The tool of  claim 1  wherein the pins are helically shaped.  
   
   
       7 . The tool of  claim 1  wherein there are multiple helical grooves.  
   
   
       8 . The tool of  claim 1  wherein the compressive spring member comprises a Belleville washer.  
   
   
       9 . A drilling system comprising: 
 a drilling string;    a mud motor for operating a drill bit in response to flow of drilling fluid through the drilling string;    a force absorbing tool incorporated within the drilling string above the mud motor; the force absorbing tool comprising: 
 an outer housing portion that is secured to a drilling string;  
 an inner mandrel portion that is secured to a mud motor;  
 the inner mandrel portion being moveable axially and rotationally with respect to the outer housing portion between an axially compressed position and an axially extended position;  
 a helical groove inscribed on the inner mandrel portion;  
 a plurality of guide pins associated with the outer housing and disposed within the helical groove; and  
 a compressive spring member to urge the inner mandrel portion toward the axially extended position.  
   
   
   
       10 . The drilling system of  claim 9  wherein the drilling string comprises coiled tubing.  
   
   
       11 . The drilling system of  claim 9  wherein the compressive spring member comprises a Belleville washer.  
   
   
       12 . The drilling system of  claim 9  wherein the guide pins each present a rounded inner contact surface contacting the helical groove.  
   
   
       13 . The drilling system of  claim 9  wherein the pins are arranged in a helical pattern to match the helical groove.  
   
   
       14 . The drilling system of  claim 9  wherein there are multiple helical grooves.  
   
   
       15 . The drilling system of  claim 9  wherein the pins are helically shaped.  
   
   
       16 . A method of absorbing axial and torsional forces associated with drilling operations by a coiled tubing-run drilling system, the method comprising the steps of: 
 incorporating a force absorbing tool into the drilling system above a mud motor;    operating a drill bit of the drilling system by flowing drilling fluid through the mud motor; and    absorbing axial and torsional shocks to the drill bit by moving an inner mandrel portion of the force absorbing tool axially and rotationally with respect to an outer housing portion of the force absorbing tool, the inner mandrel further being axially and rotationally guided by an interface of sliding of pins within helical grooves.    
   
   
       17 . The method of  claim 16  further comprising the step of urging the force absorbing tool to an axially extended position with a compressive spring member and piston.