Mass Isolation Joint for Electrically Isolating a Downhole Tool

Abstract

A mass isolation joint for electrically isolating a downhole tool includes a first joint section having a distal end in which a first thread is formed, a second joint section, and an insulating composite structure coupling the first joint section to the second joint section, wherein at least one of the first and second joint sections is adapted for coupling to the downhole tool. The insulating composite structure includes a first composite layer formed on the second joint section. The first composite layer has a second thread which engages the first thread on the distal end of the first joint section.

1 . A mass isolation joint for electrically isolating a downhole took comprising: 
 a first joint section having a distal end in which a first thread is formed;    a second joint section; and    an insulating composite structure coupling the first joint section to the second joint section, the insulating composite structure comprising a first composite layer formed on the second joint section, the first composite layer having a second thread which engages the first thread on the distal end of the first joint section;    wherein at least one of the first and second joint sections is adapted for coupling to the downhole tool.    
   
   
       2 . The mass isolation joint  claim 1 , wherein the second thread is formed on a portion of the inner composite layer formed on a distal end of the second joint section, and the distal end of the first joint section includes a recess for receiving the distal end of the second joint section and the inner composite layer formed thereon.  
   
   
       3 . The mass isolation joint of  claim 2 , wherein the first thread is formed on a wall of the recess.  
   
   
       4 . The mass isolation joint of  claim 1 , wherein the insulating composite structure further includes a sealant layer formed on the first composite layer and the distal end of the first joint section.  
   
   
       5 . The mass isolation joint of  claim 4 , wherein the sealant layer comprises an elastomeric material.  
   
   
       6 . The mass isolation joint of  claim 4 , wherein the insulating composite structure further includes a second composite layer formed on the sealant layer.  
   
   
       7 . The mass isolation joint of  claim 1 , further comprising a high-temperature adhesive disposed between the first composite layer and the first joint section.  
   
   
       8 . The mass isolation joint of  claim 7 , wherein the high-temperature adhesive is a curable material.  
   
   
       9 . The mass isolation joint of  claim 1 , wherein the first and second joint sections are made of a conductive material.  
   
   
       10 . The mass isolation joint of  claim 1 , wherein the first and second threads have a low pitch.  
   
   
       11 . A tool string for use in a borehole penetrating a subsurface formation, comprising: 
 a plurality of downhole tools; and    a mass isolation joint coupled to at least one of the downhole tools comprising:    a first joint section having a distal end in which a first thread is formed;    a second joint section; and    an insulating composite structure coupling the first joint section to the second joint section, the insulating composite structure comprising a first composite layer formed on the second joint section, the first composite layer having a second thread which engages the first thread.    
   
   
       12 . The tool string of  claim 11 , wherein the mass isolation joint is disposed between adjacent downhole tools and coupled thereto.  
   
   
       13 . The tool string of  claim 12 , wherein the mass isolation joint is coupled to the adjacent downhole tools via a rigid or flexible joint.  
   
   
       14 . The tool string of  claim 11 , wherein the downhole tools comprise logging tools.  
   
   
       15 . The tool string of  claim 11 , wherein the second thread is formed on a portion of the inner composite layer formed on a distal end of the second joint section, and the distal end of the first joint section includes a recess for receiving the distal end of the second joint section and the inner composite layer formed thereon.  
   
   
       16 . The tool string of  claim 15 , wherein the first thread is formed on a wall of the recess.  
   
   
       17 . The tool string of  claim 11 , wherein the insulating composite structure further includes a sealant layer formed on the first composite layer and the distal end of the first joint section.  
   
   
       18 . The tool string of  claim 17 , wherein the insulating composite structure further includes second composite layer formed on the sealant layer.  
   
   
       19 . The tool string of  claim 18 , wherein the sealant layer comprises an elastomeric material and the second composite layer comprises a resin composite.  
   
   
       20 . The tool string of  claim 11 , further comprising a high-temperature adhesive disposed between the first composite layer and the first joint section.