Patent Publication Number: US-2019178062-A1

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

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 15/078,812, filed 23 Mar. 2016, which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Chemical tracers have been used in the oil industry to identify treatment fluid paths and produced fluids downhole. A common method of locating the chemical tracers in the wellbore is to use tracer elements on wellscreens. The wellscreens are then deployed in the wellbore to locate the wellscreens with the chemical tracers in the desired well locations. For example, chemical tracers have been placed on screen joints at the sand face to gather data on the produced fluids. 
     As background, a completion system  10  in  FIG. 1A  has completion screen joints  50  deployed on a completion string  14  in a borehole  12 . Typically, these screen joints  50  are used for horizontal and deviated boreholes passing in an unconsolidated formation, and packers  16  or other isolation elements can be used between the various joints  50 . During production, fluid produced from the borehole  12  directs through the screen joints  50  and up the completion string  14  to the surface rig  18 . The screen joints  50  having screen jackets  60  that keep out fines and other particulates in the produced fluid. In this way, the screen joints  50  can mitigate damage to components, mud caking in the completion system  10 , and other problems associated with fines and particulates present in the produced fluid. 
     In addition to providing sand control, one or more of the screen joints  50  can include tracer material for marking produced or injected fluid in the wellbore. The tracer material can be used to mark any type of produced or injected fluids, and the tracer material can have various types of chemical compositions and can come in many different forms. For example, the tracer material can have the form of a stick, beads, powder, or paste that can be installed into a layer or space by force, by gravity, with air flow, etc. For example, the tracer material can come in the form of elements such as long strips that slip adjacent the screen jacket  60 . 
     The tracer material can be radioactive or non-radioactive. For example, the tracer material can be perfluorinated hydrocarbons encapsulated in polymer particles or the like that are sensitive to water or hydrocarbon. In this way, the polymer encapsulation can break and release the tracer material. The tracer material can also be an oligonucleotide with special functional groups and can be fluorescent, phosphorescent, or the like or can include magnetic particles or fluids, colored particles, biological material, or microorganisms. Release of the tracer material can be triggered by oil, water, gas, or a combination thereof. The type and amount of tracer material can be varied by the type of fluid and/or gas that triggers the release, by the position of the tracer material in the completion, and by the geometric position around the wellbore, and these characteristics can be varied from well to well. 
     In use, the tracer material associated with the screen joint  50  is placed adjacent a reservoir section of a well so that the flow of produced fluids can release the tracer. The placement is configured so that operators at the surface can associate the produced fluids to the sections of the wellbore and reservoir from which they are produced. With the tracer released in the produced fluids, various detection techniques can be used to detect the tracer in the produced fluid, and the particular detection technique used at surface can depend on the type of tracer employed. For example, the detection techniques can use optical, spectroscopic, chromatographic, acoustic, magnetic, capacitive, microwave, or any combination of these techniques, and the detection can involve manual or automatic sampling, monitoring, etc. of the produced fluids. 
     Chemical tracers have been used on screens in different ways. In general, typical wellscreen designs require that the tracer elements be incorporated in the screen during the screen manufacturing process, which increases costs and limits which type of chemical tracer can be used. For example, the chemical tracers can be incorporated as solid elements during the manufacturing process of the screen. The tracer elements are often placed between a sand retention layer and a basepipe of the wellscreen at a manufacturing facility. An example screen joint  50  with tracer elements is depicted in  FIG. 1B , such as disclosed in U.S. Pat. No. 8,949,029. Also, an example form of manufacture for a screen joint with tracer elements is disclosed in US 2014/0101918. 
     For wire wrap screens, the tracer is installed between the wrap wire and the basepipe of the screen between the axial ribs of the wire wrap jacket. For a metal mesh screen, the tracer can be installed underneath the drainage layer if it is a component of the screen design or adhered to the metal mesh sand control layer directly in flat narrow panels before the protective shroud is placed over as a protective jacket. Sometimes, tracers are inserted as round rods through the holes in the perforated shroud between the metal mesh layer and the protective shroud. This is difficult due to the limited space between the shroud and the metal mesh. 
     In these assembly techniques, the tracer is installed before the end rings are welded to the jackets of the wellscreen. Depending on metallurgies, some processes such as welding and post-weld heat treatment have to be considered. The tracer materials can be heat sensitive and may be exposed to welding/heat treatment operations during manufacturing that can damage the tracer materials. 
     In other manufacturing techniques, tracer can be injected into the assembled screen in a liquid form where it is allowed to cure or set into the screen. For example, manufacturers can inject a gel-like substance between the shroud and the metal mesh of a wellscreen. 
     Rather than using tracer elements in the gap between a screen and a basepipe, tracer elements can be held inside a basepipe using an insert. An example arrangement of this is depicted in  FIG. 1C . 
     Because these techniques require specific pre- and post-assembly steps, the ability to configure a screen with a tracer in the field is limited. For instance, being manufactured at the facility, the installation of the tracer occurs far from the rig location and long before the screen is deployed. The tracer material is fixed in place and cannot be changed. This reduces the opportunity to make any changes to the well design program. Another problem is that current screen constructions might limit the amount of tracer that can be installed on the screen. 
     Therefore, there is a need for a way to install a tracer in a wellscreen that is more conducive to being performed in the field. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. 
     SUMMARY OF THE DISCLOSURE 
     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&#39;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 T after the joint has been manufactured. With the tracer elements installed, the access device can be reassembled and locked in place using a locking mechanism, such as a lock nut, J-slot, crimping, channel lock, or other type of locking mechanism. Any of these 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. 
     In one embodiment, the access device has an end ring, a housing or cover, an attachment ring, and a locking ring. The end ring fixes to the basepipe to hold the jacket, and the cover is removable to provide access to spaces or layers for insertion of the tracer elements. The attachment ring provides part of the locking mechanism, and the locking ring completes the locking mechanism. Pins or set screws can also be used as part of the locking mechanism. 
     In another embodiment, the access device has an external carrier shroud that forms a tracer carrier space external to the screen jacket without diminishing mechanical strength of the screen and maintaining acceptable outer dimensions. To provide the carrier space external to the screen jacket, the shroud can have axial ribs or spacers disposed along its inner surface to create channels for insertion of the tracer elements after the screen has been manufactured. 
     The spacers can run axially along the length of the shroud to create annular channels to carry the tracer elements. The spacers can be rolled into the shroud or mechanically installed on the shroud. The number of channels can be increased and the channel size can be modified to be wider/narrower or taller/shallower to address the needs for a particular amount of tracer material and any diameter restrictions. 
     The shroud can be composed of plate metal or pipe of a specified wall thickness that is punched or drilled with holes to provide a specified open area. The open area of the shroud can be increased or decreased by changing the hole shape, size, and quantity per area. For example, the shroud&#39;s open area can be modified to address the need for more or less open area, to direct flow from the wellbore through the tracer elements to the screen, and to provide mechanical strength for the operating conditions. To form the shroud, the plate metal with the perforated openings is rolled circumferentially to a specified diameter and then welded together spirally or longitudinally to create a tube or a seamless tube can be used. 
     In the embodiments of the access device, the tracer elements for the screen jacket of the joint can be added at the end of the assembly process or long after assembly in a field operations base. In this way, the amount of tracer material that can be installed or located on the wellscreen joint can be configured as needed. For example, the access device allows operators to change the isotope formulation for the tracer material on location. Additionally, even though a given wellscreen joint may not be predetermined to hold tracer material when run downhole, the given joint can allow for tracer elements to be inserted on the fly as needed during field operations to accommodate changes in well design. 
     The basic design and performance of the screen jacket, however, is expected to remain unchanged. The open area of the sand retention layer being metal mesh or wire wrap is expected to remain the same. The disclosed access device removes the tracer installation process from the process of fabricating the wellscreen and removes the risk of damaging tracer elements during screen fabrication. 
     According to the present disclosure, a downhole assembly positions in a borehole for dispensing tracer material and includes a basepipe (e.g., tubular, casing, pipe, or the like), a filter, an end ring, and a cover ring. The filter is disposed about the basepipe and filtering fluid communication that can then pass through perforations in the basepipe. 
     The end ring is deposed on the basepipe and holds an end of the filter to the basepipe. The cover ring is disposed in place relative to the end ring. The cover ring is removable and provides access to at least one space adjacent the filter for insertion of the tracer material. 
     For example, the end ring defines at least one channel communicating adjacent the filter. An attachment ring is affixed to the basepipe, and the cover ring is removably disposed between the end ring and the attachment ring. 
     The filter can have ribs supporting the filter on the basepipe and can define a drainage layer between the filter and the basepipe. In this case, the at least one channel of the end ring can communicate with the drainage layer for the insertion of the tracer material. 
     The cover ring can have a first end abutting the end ring and can have a second end attaching to the attachment ring. Also, a lock ring can abut the second end of the cover ring and can affix to the attachment ring by threading. Moreover, the first and second ends of the cover ring can seal respectively with the end ring and the attachment ring. 
     An external shroud can be disposed about the filter and can define at least one space between the shroud and the filter. To produce the space between the shroud and the filter, the external shroud can have at least one spacer disposed on an inner surface thereof and contacting a portion of the filter to form the at least one space. 
     The external shroud can slip over the end ring and position on the filter so the cover ring can hold a portion of the external shroud on the filter. Alternatively, a portion of the external shroud can be held by the end ring. In this case, at least one channel of the end ring can communicate with the at least one space for the insertion of the tracer material. 
     According to a method of inserting tracer material in a downhole assembly after assemblage, access can be provided to at least one channel in the end ring for insertion of the tracer material adjacent the filter by removing a cover abutting between the end ring and the attachment ring disposed on the basepipe. The tracer material inserts through the at least one channel and adjacent the filter. The cover replaces between the end ring and the attachment ring and affixes in place at the attachment ring. 
     According to the present disclosure, a downhole assembly positions in a borehole for dispensing tracer material and includes a basepipe (e.g., tubular, casing, pipe, or the like), a filter, and end ring, an external shroud, and a cover ring. The external shroud slips over the end ring and positions on the filter disposed about the basepipe. The external shroud defines a space about the filter for holding the trace material. The cover ring attaches to the end ring. The cover ring is removable and provides access to the space for insertion of the tracer material adjacent the filter. 
     According to the present disclosure, a downhole assembly for dispensing tracer material includes a basepipe, an internal shroud, and fixtures. The internal shroud is disposed inside a through-bore of the basepipe and defining an annular space therewith. The shroud holds the tracer material in the annular space and permitting fluid communication between the annular space and the through-bore in the basepipe and/or the through-bore in the shroud. The fixtures are disposed on the ends of the internal shroud and hold the internal shroud in the basepipe&#39;s through-bore. 
     The fixtures can include retainer rings engaged on the ends of the internal shroud and affixed in the basepipe. The retainer rings can define central passages permitting fluid communication between the through-bores of the shroud and basepipe. The retainer rings can define peripheral passages permitting fluid communication between the basepipe&#39;s through-bore and the annular space. 
     The fixtures can include couplings affixed on the ends of the basepipe for connecting sections of basepipe together. The couplings can engage the ends of the shroud and can holding the internal shroud inside the basepipe&#39;s through-bore. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a completion system as background to the present disclosure. 
         FIG. 1B  illustrates a screen joint according to the prior art for holding tracer elements. 
         FIG. 1C  illustrates another joint according to the prior art for holding tracer elements. 
         FIGS. 2A-2B  illustrate a wellscreen of the completion system for installing tracer material in the field in a side view and a partial cross-sectional view. 
         FIG. 2C  illustrates a detailed view of an access device for the wellscreen of  FIGS. 2A-2B . 
         FIG. 3  illustrates a detailed view of another access device for the wellscreen. 
         FIG. 4  illustrates another wellscreen of the present disclosure for installing tracer material in the field or post-manufacture. 
         FIGS. 5A-5B  illustrates a shroud of yet another access device for a wellscreen. 
         FIG. 6A  illustrates a wellscreen of the present disclosure having the shroud for installing tracer material in the field or post-manufacture. 
         FIG. 6B-6D  illustrate other wellscreens of the present disclosure having the shroud for installing tracer material in the field or post-manufacture. 
         FIGS. 7A-7B  illustrate cross-sectional and end-sectional views of an internal carrier for holding chemical tracer disposed inside a basepipe. 
         FIG. 8  illustrates a perspective view of a shroud and spacers for the disclosed carrier. 
         FIG. 9A  shows an end view and a cross-sectional view of one retainer for the end of the disclosed carrier. 
         FIG. 9B  shows an end view and a cross-sectional view of another retainer for the end of the disclosed carrier. 
         FIGS. 10A-10D  illustrate a cross-sectional view, two end-sectional views, and a detailed view of another internal carrier for holding chemical tracer disposed inside a basepipe. 
         FIG. 11  illustrates a perspective view of a shroud, spacers, and end retainers for the disclosed carrier. 
         FIG. 12A  illustrates a cross-sectional view of the internal carrier of  FIG. 7A  used in a basepipe having a wellscreen. 
         FIG. 12B  illustrates a cross-sectional view of the internal carrier of  FIG. 10A  used in a basepipe having a wellscreen. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Embodiments of the present disclosure can be used with joints without screen or joints with screens. For example, embodiments of the present disclosure can be used with completion screen joints in a completion, such as generally depicted in  FIG. 1 , although other arrangements can be used. 
     Turning now to  FIGS. 2A-2C , a completion screen joint  50  is shown in a side view, a partial side cross-sectional view, and a detailed view, showing placement of tracer elements T. The screen joint  50  has a basepipe  52  with a sand control jacket  60  and an access device  70  disposed thereon. The basepipe  52  defines a through-bore  55  and has a coupling crossover  56  at one end for connecting to another joint or the like. The other end  54  can connect to a crossover or coupling (not shown) of another joint on the completion string. Inside the through-bore  55 , the basepipe  52  defines pipe ports  58 , which can be defined along the length of the basepipe  52  where the screen jacket  60  is located. Additionally, the ports  58  may be located where the access device  70  is disposed, although this is not strictly necessary. 
     The sand control jacket  60  is disposed around the outside of the basepipe  52 . As shown, the sand control jacket  60  can be a wire-wrapped screen having rods or ribs  64  arranged longitudinally along the basepipe  52  with windings of wire  62  wrapped thereabout to form various slots. Fluid from the surrounding borehole annulus can pass through the annular slots and can travel into the drainage layer D between the sand control jacket  60  and the basepipe  52 . Although the jacket  60  is shown as a wire-wrapped screen, any suitable type of screen or filter may be used. 
     One end of the jacket  60  is held to the basepipe  52  with an end ring  65 , which can be welded to the basepipe  52  and block fluid flow from the jacket  60 . The other end of the jacket  60  is held by the access device  70 . Although an end ring  65  is shown, the joint  50  may have another access device  70 . Alternatively, an inflow control device having configurable nozzles can be used, in which case any perforations  58  in the basepipe  52  would be limited to the area under the inflow control device. 
     As best shown in  FIG. 2C , the access device  70  disposed at one end of the jacket  60  has a removable cover  72 , a lock nut  74 , and an attachment ring  75  disposed about the basepipe  52  adjacent an end ring  76  for the jacket  60 . During manufacture, the jacket  60  is formed on the basepipe  52 . Then, to secure the jacket  60 , the end ring  76  is shrunk fit partially over an end of the jacket  60  and is welded to the basepipe  52  around the outer edge or held with wire locks (not shown). 
     As shown, the end ring  76  defines one or more access gaps or slots  77  that communicate under the screen&#39;s wire  62  into the drainage layer D. To seal off these slots  77  during manufacture, the attachment ring  75  is welded to the basepipe  52  a set distance from the end ring  76 . The removable cover  72  with its internal dimension  73  slips over the end of the basepipe  52  and the attachment ring  75  and abuts at one end to the end ring  76  and abuts at the other end to the attachment ring  75 . O-rings or other seals can be used to seal these abutments. To then fix the cover  72 , the lock nut  74  is slid over the basepipe  52  and then threaded to the attachment ring  75 . To complete the fixture, one or more lock fasteners  78  or the like can thread through the lock nut  74  and into the attachment ring  75 . 
     During the manufacture process, any post welding heat treatment can be performed as needed when components such as the end ring  76  and attachment rings  75  are affixed to the basepipe  52 . As already noted, tracer material may be damaged from any post weld heat treatment during manufacture. In this case, the heat treatment will not hurt any tracer elements T because they do not need to be (and preferably are not) installed yet. 
     Now that the joint  50  is manufactured, it can be handled, shipped, and stored as needed. At any point during post-manufacture and even in the field, operators can configure the joint  50  to accept tracer material. To do this, operators can remove the lock nut  74  from the attachment ring  75 , first removing any fasteners  78  and unthreading the nut  74 . The cover  72  can then slide away from the end ring  76  with the cover&#39;s inner dimension  73  passing over the attachment ring  74 . At this point, access to the drainage layer D between the screen&#39;s wire  62  and the basepipe  52  can be obtained through the one or more slots  77  in the end ring  76 . 
     Operators then insert the desired tracer material into the layer D. In general, the tracer material can be water and/or oil sensitive and can have a particular detectable signature at the surface to coordinate the location of the produced fluids with the known placement of the particular tracer material. The tracer material can be in the form of elements T that are typically a rigid, plastic-like material. They may be rectangular in cross-section being about 8.5-mm wide, 3.5-mm tall, and 1-m long. The screen jacket  60  can be several feet in length (e.g., 20-ft), and operators can fill the drainage layer D with a number of such tracer elements T. For example, hundreds of elements T can be inserted into the screen&#39;s drainage layer D. More or less tracer elements T can be added to increase the amount of time that the tracer material can be detected and used. In any event, the particulars of the use and configuration of the tracer material and elements T are dictated by the reservoir engineers. 
     With the tracer elements T installed, operators then reassemble the access device  70  so the joint  50  can be deployed downhole. Repeating assembly steps, operators slip the cover  72  to abut between the end ring  76  and the attachment ring  75  and then affix the lock nut  74  and fasteners  78 . As can be seen, the disclosed access device  70  allows operators to insert tracer elements T adjacent the screen jacket  60  while in the field or during post manufacture without having to install the elements T during the manufacture process. 
       FIG. 3  illustrates a detailed view of another access device  70  for the wellscreen. In contrast to the previous embodiment, the access device  70  incorporates a lock nut end  74   a  to the cover  72  instead of requiring a separate component. Again, to secure the jacket  60 , the end ring  76  is shrunk fit partially over an end of the jacket  60  and is welded to the basepipe  52  around the outer edge. 
     To seal off the end ring&#39;s slots  77  during manufacture, the attachment ring  75  is welded to the basepipe  52  a set distance from the end ring  76 . The removable cover  72  with its internal dimension  73  slips over the end of the basepipe  52  and the attachment ring  75  and abuts at one end to the end ring  76 . At the other end, the removable cover  72  has internal threading at its lock nut end  74   a  that threads to the attachment ring  75 . To then fix the cover  72 , one or more lock fasteners  78  or the like can thread through the cover&#39;s end  74   a  and into the attachment ring  75 . 
     Previous embodiments disclosed the jacket  60  being a wire-wrapped screen. Other types of screens can be used. As shown in  FIG. 4 , for example, a mesh screen or filter can benefit from the disclosed access device  70 . 
     The jacket  60  as a mesh screen includes rods  64 , wrapped wire  62 , mesh  66 , and a perforated shroud  68 . Similar to the previous arrangement, the end ring  76  fits partially on the end of the jacket  60  over the shroud  68 , mesh  66 , wire  62 , and rods  64 . The end ring  76  then welds to the basepipe  52 , and the other components of the access device  70  are assembled as before. In this way, tracer elements T can be inserted during post manufacture or in the field in the drainage layer D of the jacket  60 . 
     In previous embodiments, the tracer elements T have been inserted in the drainage layer D between the jacket  60  and the basepipe  52 . Other locations can also receive tracer elements. As shown in  FIGS. 5A-5B , a shroud  80  for an access device  70  of the present disclosure is shown in side cross-sectional and end views. The shroud  80  defines a plurality of perforations  84  for flow through the shroud  80 . To space the shroud  80  from other components of a wellscreen, the shroud  80  has a number of spacers  86  disposed about its inner circumference  82 . 
     The shroud  80  can be used with wellscreens for insertion and storage of tracer elements T. As shown in  FIG. 6A , for example, a wellscreen joint  50  allows tracer elements T to be installed during post-manufacture or in the field between the outer shroud  80  and the screen jacket  60 . Again, the jacket  60  can be a mesh jacket as noted previous, but any other filter can be used. In any event, the jacket  60  is assembled on the basepipe  52  as before. 
     The disclosed shroud  80  with spacers  86  is installed around the outside of the jacket  60 . Then, an end ring  76  shrink fits partially over an end of the shroud  80  and jacket  60  and is welded to the basepipe  52 . At this point, other components of the access device  70  can be assembled. Here, the attachment ring  75  is welded to the basepipe  52  a set distance from the end ring  76 . The removable cover  72  with its internal dimension  73  slips over the end of the basepipe  52  and the attachment ring  75  and abuts at one end to the end ring  76  and at the other end to the attachment ring  75 . O-rings or other seals can be used to seal the abutments. To then fix the cover  72 , the lock nut  74  is slid over the basepipe  52  and then threaded to the attachment ring  75 . To complete the fixture, one or more lock fasteners  78  or the like can thread through the lock nut  74  and into the attachment ring  75 . 
     Now that the joint  50  is manufactured, it can be handled, shipped, and stored as needed. At any point during post-manufacture and even in the field, operators can configure the joint  50  to accept tracer material. To do this, operators can remove the lock nut  74  from the attachment ring  75 , first removing any fasteners  78  and then unthreading the nut  74 . The cover  72  can then slide away from the end ring  76  with the cover&#39;s inner dimension  73  passing over the attachment ring  75 . At this point, access to the space S inside the shroud  80  can be obtained through the one or more slots  77  in the end ring  76 . 
     Operators then insert the desired tracer elements T into the space S. With the tracer elements T installed, operators then reassemble the access device  70  so the joint  50  can be deployed downhole. Repeating assembly steps, operators slip the cover  72  to abut between the end ring  76  and the attachment ring  75  and then affix the lock nut  74  and fasteners  78 . As can be seen, the disclosed access device  70  allows operators to insert tracer elements T adjacent the screen of the jacket  60  in the field or during post manufacture without having to install the elements T during the manufacture process. 
     In another example shown in  FIG. 6B , a wellscreen joint  50  allows tracer elements T to be installed during post-manufacture or in the field between an outer shroud  80  and the screen jacket  60 . The jacket  60  can be a mesh or wire-wrapped screen as noted previously, but any other filter can be used. In any event, the jacket  60  is assembled on the basepipe  52  as before. 
     An end ring  76  shrink fits partially over an end of the jacket  60  and is welded to the basepipe  52 . At this point, the access device  70  can be assembled. The disclosed shroud  80  with spacers  86  is installed around the outside of the jacket  60 . As can be seen, the internal dimension of the shroud  80  can be greater than the outer dimension of the end ring  76  so that the shroud  80  can slide over the end ring  76 . As an alternative, the shroud  80  may be manufactured on the outside of the jacket  60  by circumferentially wrapping plate metal and welding along its seam(s). 
     With these components installed, an end ring cover  72  installs on the end ring  76  and abuts against the shroud  80  and encloses the space S for the tracer elements T. O-rings or other seals can be used to seal the abutments. The end ring cover  72  affixes to the end ring  76  using threading  74   b , for example, and fasteners  78  in a manner similar to the lock nuts discussed previously. 
     Because the joint  50  is manufactured, it can be handled, shipped, and stored as needed. At any point during post-manufacture and even in the field, operators can configure the joint  50  to accept tracer material. To do this, operators can remove the end ring cover  72 , first removing the fasteners  78  and then unthreading the cover  72  from the end ring  76 . At this point, access to the space S inside the shroud  80  can be obtained. 
     Operators then insert the desired tracer elements T into the space S. With the tracer elements T installed, operators then reassemble the access device  70  so the joint  50  can be deployed downhole. As can be seen, the disclosed access device  70  allows operators to insert tracer elements T adjacent the screen joint  60  in the field or during post manufacture without having to install the elements T during the manufacture process. 
       FIG. 6C  shows an example of the access device  70  providing access to both the drainage layer D of the jacket  60  and the space S of a shroud  80 . The end ring  76  affixes the jacket  60  in a manner similar to the embodiment of  FIG. 6B , and the cover  72  has threads  74   b  that thread onto the end ring  76  to hold the shroud  80  and provide access to its space S. Additional access to the drainage layer D for placement of tracer elements T can be made through one or more slots  77  in the end ring  76 . The cover  72  has a lock nut end  74   a  that threads onto an attachment ring  75  affixed to the basepipe 
     The arrangement of  FIG. 6C  allows for more tracer material to be placed adjacent the jacket  60  by providing both the shroud&#39;s space S and the drainage layer D. Also, if desired for an implementation, a full set of one type of tracer material can be used for the elements T in the space S, while a full set of a different type of tracer material can be used for the elements in the drainage layer D. These different types of elements T may respond to different types of fluid so that operators can make multiple determinations about produced fluids and the like. 
     Finally,  FIG. 6D  shows an example of the access device  70  providing access to the space S of a shroud  80 , but also acting as an inflow control device. The end ring  76  affixes the jacket  60  in a manner similar to the embodiment of  FIGS. 6B-6C , and the cover  72  has threads  74   b  that thread onto the end ring  76  to hold the shroud  80  and provide access to its space S. The cover  72  also has a lock nut end  74   a  that threads onto an attachment ring  75  affixed to the basepipe  52 . 
     The end ring  76  includes one or more slots  77  in which one or more configurable nozzles  90  are disposed. Screened fluid from the drainage layer D can pass through any of the open configurable nozzles  90  (i.e., those lacking a plug  92 ) to experience a pressure drop before passing into one or more perforations  58  in the basepipe  52  under the device  70 . Operators can configure the joint  50  to hold tracer elements T in the space S of the shroud  80  and configure the nozzles  90  by removing and then replacing the cover  72 . It may be further possible to insert tracer elements T if desired in the drainage layer by removing and replacing the restrictive nozzles  90  in the end ring&#39;s slots  77 . 
     Given that the embodiment of the end ring  76  in  FIG. 6D  includes nozzles  90  in the slots  77  and can provide access to the drainage layer for insertion of tracer element T, it will be appreciated that the end rings  76  for the embodiments of  FIGS. 2C, 3, and 4  could also include such nozzles  90 . 
       FIGS. 7A-7B  illustrate cross-sectional and end-sectional views of an internal carrier  100  for holding chemical tracer disposed inside a joint  50  having a basepipe  52 , which can be casing or other tubing. In this arrangement, the basepipe  52  may not define perforations and may not have a wellscreen. The internal carrier  100  positions in the through-bore  55  of the basepipe  52  and includes a shroud  110  affixed by retainers  120 ,  130  at both ends in the bore  55 . 
     The shroud  110 , which is shown in a perspective view of  FIG. 8 , is a cylindrical pipe or tube having an internal passage  112  and perforations  114 . In an alternative arrangement, the shroud  110  can be wire-wrapped screen or other permeable fixture. The flow area provided by the perforations  114  or the like can be configured for a particular implementation. 
     When disposed in the basepipe&#39;s bore  55 , the shroud&#39;s passage  112  completes the fluid passageway through the basepipe  52 , albeit with a reduced dimension in some cases. A number of spacers  116  can be affixed about the circumference of the shroud  110  to make a number of separate pockets or gaps for holding tracer elements. The spacers  116  can have any particular shape and are shown as hollow tubes in the current example. In general, the spacers  116  can be tubes, rods, other shapes that are readily available and are stitch welded on the inner shroud  110 , making it cost effective for manufacture. 
     To hold the shroud  110  inside the basepipe&#39;s bore  55 , one or more retainers  120 ,  130  at both ends of the shroud  110  engage the shroud  110  and affix to the bore  55 . Two retainers  120 ,  130  are used at both ends to facilitate assembly, but other implementations may use a different arrangement of retainers. The two retainers  120 ,  130  include a spacing retainer  120 , which is shown in an end view and a cross-sectional view in  FIG. 9A , and includes a transition retainer  130 , which is shown in an end view and a cross-sectional view in  FIG. 9B . 
     The spacing retainers  120  fit partially on the free-ends of the shroud  110  and include a central passage  122  to communicate with the passage  122  of the spacing retainer  120 ,  112  of the shroud  110 , and the bore  55  of basepipe  52 . Various peripheral slots  126  can be defined around the outside of the central passage  122  to communicate fluid into the annular space between the shroud  110  and pipe&#39;s bore  55 . External thread  124  can be provided on the exterior of the spacing retainers  120  to thread into internal thread  53  defined in portions of the pipe&#39;s bore  55 . Spacing retainer  120  has a counterbore to centralize the shroud  110  in the bore  55  of basepipe  52 . 
     The transition retainers  130  fit against the spacing retainers  120  and include a central passage  132  to communicate with the passages  112 ,  122  of the shroud  110  and spacing retainers  120 . Various peripheral slots  136  can be defined around the outside of the central passage  132  to communicate fluid into the annular space between the shroud  110  and pipe&#39;s bore  55 . External thread  134  can be provided on the exterior of the transition retainers  130  to thread to the internal thread  53  defined in the pipe&#39;s bore  55 . Preferably, the central passages  132  of these retainers  130  define a transition  133  to mate the dimension of the pipe&#39;s bore  55  with the dimension of the central passage  132 . This transition  133  can be a 20-degree chamfer or the like to ease the entry of wireline tractors and other tools to be passed through the joint  50 . Counter bores  135  can be defined on the inside edge of the transition retainers  130  at the peripheral slots  136  to minimize any misalignment between the peripheral slots  136  with the slots  126  of the spacing retainer  120 . 
     Assembly of the carrier  100  with tracer elements can involve fitting retainers  120 ,  130  inside the pipe&#39;s bore  55  at one end. The two retainers  120 ,  130  thread inside the pipe&#39;s thread  53  and can be tightened against one another to lock in place. Operators can fit the shroud  110  partially in the pipe&#39;s bore  55  and can insert the tracer elements in the annular space separated by the spacers  116 . Once fitted with the proper type(s) and amount(s) of tracer elements, the shroud  110  can be inserted into the pipe&#39;s bore  55  so that the shroud&#39;s free-end engages the lip of the spacing retainer  120 . At this point, operators can complete the assembly by installing the other retainers  120 ,  130  in the pipe&#39;s bore  55  at the other end of the shroud  110  to hold it in place. 
     When the basepipe  52  with the carrier  110  is installed downhole, fluid flow through the basepipe  52  can activate the tracer elements carried in the annular space around the shroud  110 . Fluid flow into the annular space can be facilitated by the peripheral slots  126 ,  136  in the retainers  120 ,  130 . Chemical tracer entrained in the flow can enter the main flow through the basepipe  52  via the perforations  114  in the shroud  110 . In an alternate scenario, the fluid flow into the annular space is facilitated by the perforations  114 , and the chemical tracer entrained in the flow can exit through the peripheral slots  126 ,  136  in the retainers  120 ,  130 . In the disclosed embodiment, the modular structure of the carrier  100  facilitates easy assembly and can help when maintenance is required. 
       FIGS. 10A-10D  illustrate a cross-sectional view, two end-sectional views, and a detailed view of another internal carrier  150  for holding chemical tracer disposed inside a joint  50  having a basepipe  52 , which can be casing or other tubing. Again in this arrangement, the basepipe  52  may not define perforations and may not have a wellscreen. The internal carrier  150  positions in the through-bore  55  of the basepipe  52  and includes a shroud  160  affixed by retainers  170  at both ends in the bore  55 . 
     The shroud  160 , which is shown in a perspective view of  FIG. 11 , is a cylindrical pipe or tube having an internal passage  162  and perforations  164 . In an alternative arrangement, the shroud  160  can be wire-wrapped screen or other permeable fixture. Again, the flow area provided by the perforations  164  or the like can be configured for a particular implementation. 
     When disposed in the basepipe&#39;s bore  55 , the shroud&#39;s passage  162  completes the fluid passageway through the basepipe  52 . A number of spacers  166  can be affixed about the circumference of the shroud  160  to make a number of separate pockets or gaps for holding tracer elements. The spacers  166  can have any particular shape and are shown as solid wire in the current example. In general, the spacers  166  can be tubes, rods, other shapes that are readily available and stitch welded on the inner shroud  160 , making it cost effective for manufacture. 
     To hold the shroud  160  inside the basepipe&#39;s bore  55 , retainers  170  at both ends of the shroud  160  engage the shroud  160  and affix it in the bore  55 . The retainers  170 , shown in detail in  FIG. 10D , have a threaded lip  174  to thread on ends of the shroud  160 . A central passage  172  of the retainers  170  complete the shroud&#39;s internal passage  162 . A transition  173  may be provided on the outer edge of the retainer  170 . In any event, the dimension of the shroud&#39;s passage  162  and the retainer&#39;s passage  172  are configured to match the dimension of the pipe&#39;s bore  55  so that restriction through the basepipe  52  is minimized. In another variation, slots (not shown) on the outer periphery of the retainer  170  can facilitate the flow of fluids. 
     The retainers  170  fit on the ends of the shroud  160  and hold it axially in the basepipe  52  between crossovers or couplings  57  that affix on both ends of the basepipe  52 . The crossover or couplings  57  can have a box end that threads to a pin end of the basepipe  52 . The couplings  57  can also have a pin or box end for affixing to other components of an assembly. In an alternate arrangement depending on their dimensional constraints, the basepipe  52  can have a box end, and the crossover or couplings  57  can have a pin end. 
     Assembly of the carrier  150  with tracer elements can involve fitting a retainer  170  on a far end of the shroud  160  and fitting a crossover or coupling  57  on the far end of the basepipe  52 . The shroud  160  can fit partially inside the pipe&#39;s bore  55  at the near end. Operators can insert the proper type(s) and amount(s) of tracer elements in the annular space separated by the spacers  166 . The other retainer  170  can affix to the near end of the shroud  160 , and the shroud  160  can be inserted into the pipe&#39;s bore  55  so that the shroud&#39;s retainer  170  engages the inner shoulder of the far crossover or coupling  57 . At this point, operators can complete the assembly by installing the near crossover or coupling  57  at the near end of basepipe  52  to hold the shroud  160  in place. 
     When the basepipe  52  with the carrier  160  is installed downhole, fluid flow through the basepipe  52  can activate the tracer elements carried in the annular space around the shroud  160 . Chemical tracer entrained in the flow can enter the main flow through the basepipe  52  via the perforations  164  in the shroud  160 . In an alternate scenario, the fluid flow into the annular space is facilitated by the perforations  164  in the shroud  160 , and chemical tracer entrained in the flow can exit through the annular space around the shroud  160 . Overall, the modular structure of the carrier  160  facilitates easy assembly and can help when maintenance is required. 
     In the above arrangements of  FIGS. 2A-6B , tracer elements are disposed external to a basepipe allowing for wetting of fluid flow from the borehole annulus to the tubing string with tracer. It will be appreciated that the arrangements of  FIGS. 2A-6B  can be used with basepipes  52  lacking perforations. This would equate to an annular wetting arrangement where the tracer elements wet the flow of fluid in the borehole annulus without passing into the basepipe  52 . The fluid could pass into a tubing string elsewhere in an assembly. 
     In the above arrangements of  FIGS. 7A-11 , the internal carriers  100 ,  150  have been used inside basepipes  50  lacking perforations and wellscreens. This equates to a tubing wetting arrangement for entraining tracer in fluid passing through a tubing string. It will be appreciated that each of the internal carriers  100 ,  150  can be used in other implementations, including those having basepipe&#39;s with perforations and those having perforations and wellscreens. 
     Accordingly, a combined wetting arrangement can be used in which both annular and tubing wetting of the fluid flow can be achieved. For example,  FIG. 12A  illustrates a cross-sectional view of the internal carrier  100  of  FIG. 7A  used in a basepipe  52  having perforations  58 . As another example,  FIG. 12B  illustrates a cross-sectional view of the internal carrier  150  of  FIG. 10A  used in a basepipe  52  having perforations  58 . In both of these examples, the basepipe  52  can have a wellscreen or jacket  60  disposed external to the perforations  58  and secured to the basepipe  52  with end rings  65  or the like. The end ring  65  can be welded or wire-locked in place. 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter. For example, a screen as in  FIGS. 2A-2B  can have an access device  70  on both ends instead of just one. In another example, one end of the internal shroud can have a retainer ring as in  FIG. 7A  on one end and can be held by a coupling as in  FIG. 10A . In other examples, any over the various access devices, shrouds, screens, end rings, attachment rings, covers, cover rings, and the like can be combined to increase or decrease space and access available for trace material. 
     In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.