Methods and apparatus for monitoring components of downhole tools

Abstract

Disclosed herein is a surface controlled subsurface safety valve (SCSSV) that includes a moveable component of the SCSSV and a stationary component of the SCSSV. A sensor element is also included which is configured to sense position of the moveable component relative to the stationary component. Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.

1 . A downhole tool comprising:
 a moveable component of the downhole tool;   a stationary component of the downhole tool; and   a sensor element positioned and configured to be physically compressible by a portion of one of the moveable component and the stationary component against the other of the moveable component and the stationary component only during some moveable component positions to sense position of the moveable component relative to the stationary component.   
   
   
       2 . A downhole tool as claimed in  claim 1  wherein the sensor element is a magnetostrictive material having predictable change in magnetic permeability when stressed. 
   
   
       3 . A downhole tool as claimed in  claim 1  wherein the sensor is a mechanical switch type sensor. 
   
   
       4 . A downhole tool as claimed in  claim 1  wherein the moveable component is a closure member. 
   
   
       5 . A downhole tool as claimed in  claim 1  wherein the moveable component is a flow tube. 
   
   
       6 . A downhole tool as claimed in  claim 1  wherein the moveable component is a piston. 
   
   
       7 . A downhole tool as claimed in  claim 4  wherein the closure member includes a cam surface configured to bear against the sensor element to effect the physical compression of the element in one of an open condition and a closed condition of the closure member. 
   
   
       8 . A downhole tool as claimed in  claim 6  wherein the piston includes a magnet and the stationary component supports the sensor element which is configured to sense the magnet. 
   
   
       9 . A downhole tool as claimed in  claim 4  wherein the closure member supports the sensor element such that the sensor element is in communication with a torsion spring locating against the closure member. 
   
   
       10 . A downhole tool as claimed in  claim 10  wherein the sensor element is in communication with a power spring. 
   
   
       11 . A downhole tool as claimed in  claim 1  wherein the sensor element is two sensor elements, one positioned at one end of the travel of the moveable component and the other positioned at another end of travel of the moveable component. 
   
   
       12 . A downhole tool as claimed in  claim 11  wherein the sensors are carried by the moveable component. 
   
   
       13 . A downhole tool as claimed in  claim 12  wherein the sensors are carried by the stationary component. 
   
   
       14 . A method for sensing position of an object comprising:
 placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component;   causing a stress on the material with the separate component; and   measuring a change in magnetic permeability of the material.   
   
   
       15 . A method for sensing position for an object comprising:
 placing a magnetostrictive material in a location, the location including a coil;   applying a current to the coil;   measuring magnetic permeability of the material; and   comparing measured magnetic permeability to known permeability of the magnetostrictive material in an unstressed condition.   
   
   
       16 . A method for sensing position for an object as claimed in  claim 15  where the method further comprises:
 determining whether the material is stressed to conclude a position of the object in one of in contact with the material and spaced from the material.