Abstract:
A structure and technique is disclosed to allow passing control lines, conduits or cables of all sorts through a downhole tool. The assembly provides for passage of the conduit or cable through and into the bore of the downhole tool, protected by an internal carrier. The end connections are assembled without any twisting force applied to the cable or conduit. The end connections resist torque. A jam nut on either end provides one seal, and internal seals are used against the mandrel of the downhole tool to further provide pressure isolation where the cable or conduit enters the tool body or exits. Tensile loads are passed through the tool body rather than the cable or conduit. There is complete pressure isolation between the conduit and both the tubing and the annulus.

Description:
FIELD OF THE INVENTION 
     The field of this invention relates to extending conduits or cables through one or more downhole tools, particularly where the tools, when actuated, engage an interior wall of a casing or tubular. 
     BACKGROUND OF THE INVENTION 
     In many downhole applications, it is necessary to run small-diameter conduits or various signal, power, or fiber optic cables downhole for a variety of control and measurement purposes. Frequently, conduits or cables of whatever type must extend past such structures as packers which, when set, completely isolate one portion of the wellbore from another. Various techniques have been used to get conduits and cables past the packing element and setting mechanism of such downhole tools as packers. In some designs, the body of the packer is made additionally thick so that a parallel path can be drilled through the body. This parallel path can literally allow a cable or conduit to pass therethrough with seals on top or bottom. Alternatively, the conduit can be broken at either end of the passage and the passage itself becomes an extension of the conduit. However, this design has the unique disadvantage in that space is limited downhole. Thus, the provision of the additional path or paths to accommodate cables or conduits or both necessarily results in a decreasing available diameter for the main bore through the packer. Thus, a reduction in the I.D. of the bore of the packer, or other downhole tool, limits its usefulness because it restricts flow as well as making it difficult, if not impossible, to pass tools through it to perform procedures further downhole below the tool. Another difficulty with this design is that there are many components that make up the body of the downhole tool, such as a packer. All the components have to be assembled so that the bore in each piece is in alignment so that the conduit or cable can pass through. 
     Another alternative is to place connectors in the conduit above and below a parallel path through the body of the downhole tool such that the conduit, for example, does not literally pass through the parallel path but terminates at an upper end with a connector and resumes at the lower end of the parallel path with another connector. This has the disadvantage of introducing more connections with potential leakpaths. Additionally, in some applications, thermal loads can become an issue which require coiled sections of the conduit around the downhole tool to compensate for differential expansion. 
     The use of parallel paths in many cases requires an eccentric design where the main bore through the downhole tool, such as the packer, is off-center to allow room for the various parallel paths for the control lines or cables. Additionally, very long bores under the element of a packer through its body are expensive to fabricate. 
     In other designs, rotation is required to make up the end connections on at least one end of the downhole tool, with the tubing or cable extending through the tool. This requires the allocation of sufficient slack in the cable or tubing to allow for final make-up. Additionally, in those prior designs, the end connections would not necessarily be designed for torque resistance. Thus, applied torque could stress the line or cable, causing a cut or leak. One such prior design, which breaks the control line and provides a parallel passage while providing no torque resistance on one end where the control line is connected, is the FHL Packer provided by Baker Oil Tools. 
     Accordingly, one of the objectives of the present invention is to provide an ability to feed the control line or cable through a downhole tool without twisting. Another feature is to minimize orientation issues in feeding the cable or control line through the downhole tool. Another objective is to provide torque resistance which, at the same time, can ease alignment so that the cable or conduit can be simply fed through the downhole tool. Another objective is to provide protection for cables or control lines as they pass through the body of the tool without having to go through a separate and discrete path from the main wellbore, which would in turn reduce the available diameter for the bore through the tool. Another objective is to be able to provide a seal around the cable or conduits. Such seals could also be metal-to-metal, if necessary. Yet another objective is easy passage of single or multiple control lines or cables and increased reliability of objects passing in a conduit since the conduit can be continuous. These and other objectives will be more readily understood by those skilled in the art from a review of the preferred embodiment of the invention described below. 
     SUMMARY OF THE INVENTION 
     A structure and technique is disclosed to allow passing control lines, conduits or cables of all sorts through a downhole tool. The assembly provides for passage of the conduit or cable through and into the bore of the downhole tool, protected by an internal carrier. The end connections are assembled without any twisting force applied to the cable or conduit. The end connections resist torque. A jam nut on either end provides one seal, and internal seals are used against the mandrel of the downhole tool to further provide pressure isolation where the cable or conduit enters the tool body or exits. Tensile loads are passed through the tool body rather than the cable or conduit. There is complete pressure isolation between the conduit and both the tubing and the annulus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a-g  show a sectional elevation, illustrating the present invention applied to a downhole packer. 
     FIG. 2 is a perspective view, part cut-away, of FIG. 1 a.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 a-g  illustrate a packer of known construction insofar as it relates to the sealing assembly  10 , the lower slip assembly  12 , the locking assembly  14 , and the setting assembly  16 . Although a packer is illustrated, other types of downhole tools can be used with the components described for this invention. 
     The upper slip assembly  18  comprises an upper slip cage  20 , which further comprises a thread  22 . A mandrel  24  extends from FIG. 1 a  through FIG. 1 g.  A top sub  26  fits over mandrel  24  and has a thread  28  to mate up with thread  22  on upper slip cage  20 . The mandrel  24  has an external thread  30 . A split ring  32  has an internal thread  34  which mates with thread  30  on mandrel  24 . Top sub  26  has a pair of seal rings  36  and  38  which seal between the top sub  26  and the mandrel  24 . Top sub  26  has a passage  40  which has an end  42  internally adjacent end  44  of mandrel  24 . The other end of passage  40  is external at surface  46 . There is a thread  48  at end  50  of passage  40 . A jam nut  52  is designed to go over a conduit or cable  64  which passes therethrough in a passage  54 . Conduit as used in this application is intended to encompass all forms of conveyances for signal or power downhole, including but not limited to tubular structures, cable of any type, such as electrical or fiber optic, for example. The conduit is sealingly inserted through passage  54 , and jam nut  52  can be threaded to thread  48  so as to provide a preferably metal-to-metal seal between sloping surfaces  56  and  58 . A carrier  60  extends from FIG. 1 a  through FIG. 1 g.  As shown in FIG. 2, the carrier  60  has a series of longitudinal passages such as  62 , each of which can accept a conduit  64 . Thus, the carrier  60  defines a passage which begins adjacent end  42  of passage  40  and extends through the downhole tool to the assembly shown in FIG. 1 g , which is the mirror image of the assembly shown in FIG. 1 a.    
     Referring now to FIG. 2, it can be seen that the mandrel  24  has a series of splines  66 . The top sub  26  also has a series of splines  68  which can be used for alignment of the top sub  26  when bringing it down and over the split ring  32  and the upper slip cage  20 . Rotation of the upper slip cage  20  secures the entire assembly because of the engagement of threads  22  and  28 . The split ring  32  prevents axial movement of the top sub  26  such that rotating upper slip cage  20  brings it up. By virtue of the engagement of threads  30  and  34 , the split ring  32  cannot translate. The top sub  26 , when threaded to slip cage  20 , holds the split ring  32  against mandrel  24  due to the interengagement of threads  30  and  34  and the overlap of top sub  26  over split ring  32 . Thus, upon sufficient rotation of the upper slip cage  20 , the top sub  26 , which cannot rotate because of the interengagement of splines  66  and  68 , translates downwardly until it is drawn against the split ring  32 . At that time, a pin  70  (see FIG. 2) is inserted to retain the assembled position. 
     Referring now to FIG. 1 g,  the same structure is disposed on the lower end of the downhole tool as was previously described on the upper end. A split ring  72  has a thread  74  which engages a thread  76  on the mandrel  24 . Splines  78  on bottom sub  80  engage splines  82  on mandrel  24 . Seals  84  and  86 , which can be resilient or metallic or other suitable materials for the temperatures and chemicals in the surrounding environment, seal between the bottom sub  80  and the mandrel  24 . Bottom sub  80  has at least one passage  88  onto which a jam nut  90  can be secured, which in turn has a passage  92  to allow the extension of a control line or cable (not shown) sealingly therethrough. The jam nut  90  has a tapered sealing surface  94  which helps to provide another seal in the bottom sub  80  to back up seals  84  and  86 . In the packer illustrated in FIG. 1, the setting retainer nut  96  has a thread  98  which engages thread  100  on bottom sub  80 . With the splines  78  and  82  in engagement, rotation of setting retainer nut  96  will draw up bottom sub  80  against the split ring  72 . The carrier  60  extends downwardly into contact with the bottom sub  80 . 
     Those skilled in the art can now see that there are several features to the above-described assembly. First, the splines  66  and  68  allow torque to be transmitted from the top sub  26  to the mandrel  24  without any applied stresses to the conduit  64  which extends through passage  40 . The same thing occurs at the lower end where splines  78  and  82  transmit torque from the mandrel  24  to the bottom sub  80  without putting any stresses on any conduits which extend through a given passage  88 . Without these splines or equivalent structure which can transmit torque, the conduits which extend through the tool shown in FIG. 1 or any other downhole tool, there exists a possibility for cracking, breaking or tearing due to relative rotational movement of the components. 
     Similarly, longitudinal stresses are not borne by any conduit which extends from passage  40  and through passage or passages  62  in the carrier  60 , over to passage  88  in bottom sub  80 . Longitudinal stresses are transmitted through the split rings  32  and  72  due to the interengaging thread pairs  30  and  34  and  74  and  76 , respectively. Accordingly, any conduit extending through the downhole tool is further insulated from longitudinal loads which are transmitted into the mandrel  24 . The number and size of the various passages  40  can be varied to allow the use of one or more conduits of similar or differing sizes. Clearly, the assemblies at the top and bottom are identical to accommodate the passage of any given number of conduits through the tool. 
     The carrier  60  has a matching number of passages  62  to accommodate the number of passages  40  and  88  at the top and bottom of the tool, respectively. In that way, the carrier  60  creates protected runs inside the tool so that the passage of equipment through the inside of the tool does not result in any damage to the conduits running through the protected passages  62  in the carrier  60 . Sealing around the mandrel  24  occurs, for example, at the top end due to the presence of sealing surface  56  on jam nut  52  engaging sealing surface  58 . In the other direction, the seal pair  36  and  38 , which can be of a resilient material such as an elastomer, or can be made of a metallic substance or a composite material or other material suitable for the pressures, temperatures and chemical environment, prevents leakage past the threaded connection of threads  22  and  28 . A seal that is preferably metal to metal contact can also be used here. The same can be said for the equivalent assembly at the lower end of the tool. 
     One order of assembly involves extension of the conduit inside the mandrel  24  and through the passage  88  in bottom sub  80 . The splines  78  and  82  are aligned after the split ring  72  is placed on the mandrel  24  with threads  74  and  76  in engagement. The bottom sub  80 , with the conduits extending through the various respective passages  88 , is brought into contact with the setting retainer nut  96 , and the setting retainer nut  96  is rotated to make up threads  98  and  100 . This draws up the bottom sub  80  until it contacts the split ring  72 , fixing split ring  72  in position against the setting retainer nut  96 . Thereafter, the jam nuts  90  are made up around each individual conduit in each respective passage  88 . It should be noted that at this time, the carrier  60  has not yet been installed. With the conduits now extending through the mandrel  24 , the carrier  60  can be slipped in through the upper end after first aligning each of the conduits with their respective passage  62  in carrier  60 . In that sense, the conduits act as a guide for the carrier  60 , which may be built in one piece or in several pieces for ease of handling and shipping. The carrier structure  60  is then inserted into the mandrel  24  until it bottoms on bottom sub  80  and comes up to where the top sub  26  will ultimately be installed. The conduits, having previously been fed through the passages  40  in top sub  26 , are now in their final position. What remains to be done is to bring the top sub  26  down to the upper slip cage  20  to make up thread  28  to thread  22 . This is done after the placement of the split ring  32  onto the mandrel  24  so as to allow threads  30  and  34  to engage. The splines  66  and  68  guide the top sub  26  so it cannot rotate. Rotation of the slip cage  20  advances longitudinally the top sub  26  so as to trap the split ring  32 . Thereafter, the jam nuts  52  are applied to each of the conduits through a given passage  40  so as to sealingly secure each of the passages  40  and thereby retain the pressure inside the mandrel  24 . Seals  36  and  38  also operate to retain the pressure within the mandrel  24 . Other sealing systems can be employed as between the mandrel  24  and the top sub  26 , or the mandrel  24  and the bottom sub  80  without departing from the spirit of the invention. Other sealing systems can be used for the jam nuts  52  and  90  without departing from the spirit of the invention. Sealing can also be done between the top sub  26 , bottom sub  80 , and carrier  60  without departing from the spirit of the invention. This means retention of pressure in the carrier  60 . Other orders of assembly are possible without departing from the spirit of the invention. The important thing is that the construction is adaptable to any number of downhole tools, not necessarily the known packer illustrated in FIG.  1 . The assembly is quick and easy and provides the sealing reliability that is demanded by the end users. No longer are expensive constructions required to provide downhole tool bodies with dedicated passages for conduits. Additionally, since the assembly can occur without having to twist the conduits, additional runs of conduit do not need to be provided to accommodate all the twisting necessary for final assembly as done in the past. Instead, the profile of the downhole tool does not need to be needlessly increased, which is an advantage which can give the maximum bore size available in the mandrel  24 . This design also promotes interchangeability for a variety of applications by simply using different carriers  60  in conjunction with similarly matched upper and lower subs so that a host of different combinations of conduits can be accommodated while using the same underlying tool. 
     The main advantages are fewer joints in conduits since no joints are required to pass by tools, the cables or conduits are protected, the assembly is fast and easy, and torque is transferred at both ends through the mandrel. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.