Apparatus for Carrying Chemical Tracers on Downhole Tubulars, Wellscreens, and the Like

Abstract

An access device installs on a wellscreen joint during manufacture and allows access to one or more spaces or layers where tracer elements can be installed adjacent the joint's screen jacket (i.e., internal and/or external to the screen jacket). Portion of the access device is removable to allow installation of the tracer elements after the joint has been manufactured. With the tracer elements installed, the access device can be reassembled and locked in place. Any various mechanism can allow the access device to be partially removed, the tracer elements to be installed, and the access device to be reassembled in place. For example, an end ring holding the jacket on the basepipe can have at least one channel communicating with a space or layer for insertion of the tracer elements. A removable cover can be removed to allow access to the at least one channel and can be reattached for the wellscreen to be used downhole.

What is claimed is: 
     
         1 . A downhole assembly positioning in a borehole for dispensing tracer material, the assembly comprising:
 a basepipe having a throughbore;   a filter disposed on the basepipe and filtering fluid communication between the borehole and the through-bore;   an end ring disposed on the basepipe and holding an end of the filter in place on the basepipe; and   a cover ring disposed in place relative to the end ring, the cover ring being removable and providing access to at least one space adjacent the filter for insertion of the tracer material.   
     
     
         2 . The assembly of  claim 1 , wherein the basepipe defines one or more perforations communicating fluid between the filter and the through-bore. 
     
     
         3 . The assembly of  claim 1 , further comprising an external shroud slipped over the end ring and positioned on the filter, the external shroud defining the at least one space adjacent the filter, the cover ring removably disposed relative to the end ring to hold a portion of the external shroud in place on the filter and to provide the access to the at least one space. 
     
     
         4 . The assembly of  claim 3 , wherein the end ring comprises external thread, and wherein the cover ring comprises internal thread threading to the external thread. 
     
     
         5 . The assembly of  claim 1 , wherein the end ring defines at least one channel communicating adjacent the filter, the cover ring removably disposed relative to the end ring to provide access to the at least one space through the at least one channel. 
     
     
         6 . The assembly of  claim 5 , wherein the filter defines a drainage layer as the at least one space between the filter and the basepipe, the at least one channel of the end ring communicating with the drainage layer. 
     
     
         7 . The assembly of  claim 5 , further comprising an attachment ring disposed on the basepipe, wherein the cover ring comprises first and second ends, the first end abutting the end ring, the second end removably attaching to the attachment ring. 
     
     
         8 . The assembly of  claim 7 , further comprising a first seal disposed between the first end of the cover ring and the end ring; and a second seal disposed between the second end and the attachment ring. 
     
     
         9 . The assembly of  claim 7 , wherein the attachment ring comprises an external thread; and wherein the second end of the cover ring comprises an internal thread removably threading to the external thread. 
     
     
         10 . The assembly of  claim 4 , further comprising an attachment ring disposed on the basepipe; and a lock ring removably attaching to the attachment ring, wherein the cover ring comprises first and second ends, the first end abutting the end ring, the second end abutting the lock ring on the attachment ring. 
     
     
         11 . The assembly of  claim 10 , further comprising a first seal disposed between the first end of the cover ring and the end ring; and a second seal disposed between the second end and the attachment ring. 
     
     
         12 . The assembly of  claim 10 , wherein the attachment ring comprises an external thread, and wherein the lock ring comprises an internal thread removably threading to the external thread. 
     
     
         13 . The assembly of  claim 1 , further comprising an external shroud disposed about the filter and defining the at least one space between the external shroud and the filter. 
     
     
         14 . The assembly of  claim 13 , wherein at least one channel of the end ring communicates with the at least one space between the external shroud and the filter. 
     
     
         15 . The assembly of  claim 13 , wherein the external shroud comprises at least one spacer disposed on an inner surface thereof and contacting a portion of the filter to form the at least one space. 
     
     
         16 . The assembly of  claim 13 , wherein the end ring holds a portion of the external shroud in place on the filter. 
     
     
         17 . The assembly of  claim 13 , wherein the external shroud slips over the end ring and positions on the filter, the cover ring holding a portion of the external shroud in place on the filter. 
     
     
         18 . The assembly of  claim 17 , wherein the end ring comprises at least one channel communicating with a drainage layer between the filter and the basepipe for insertion of an additional amount of the tracer material. 
     
     
         19 . The assembly of  claim 18 , further comprising an attachment ring disposed on the basepipe, wherein the cover ring comprises first and second ends, the first end abutting the external shroud, the second end removably attaching to the attachment ring 
     
     
         20 . A method of inserting tracer material in a downhole assembly after assemblage, the downhole assembly having a basepipe with a filter disposed thereabout, the filter having an end ring holding an end of the filter in place on the basepipe, the method comprising:
 providing access to at least one space adjacent the filter for insertion of the tracer material by removing a cover ring removably disposed relative to the end ring;   inserting the tracer material in the at least one space adjacent the filter with the provided access; and   replacing the cover ring relative to the end ring.