Abstract:
Devices and methods are described for disposing electric, hydraulic and/or optical cables or conduits axially through a hydrostatically-set packer mechanism. Radial fluid communication is also provided through the inner mandrel so that the packer mechanism may be set using hydrostatic pressure within the flowbore. Feed-through paths for the cables or conduits isolate the cables/conduits from fluid pressure as well as axial or torsional tensile forces.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates generally to the design of downhole packers and to mechanisms for passing cables and conduits through a packer. In particular aspects, the invention relates to the design of packers that are set using hydrostatic wellbore fluid pressure.  
         [0003]     2. Description of the Related Art  
         [0004]     When installing a production string within a wellbore, it is often necessary to form a fluid seal within a large diameter opening, such as an open (uncased) hole. To accomplish this, a packer assembly is needed that can provide large radial expansion of the sealing element. Unfortunately, conventional large expansion packer systems generally lack the ability to pass electrical or fiber optic cables or fluid conduits axially through the packer assembly so that other devices may be used below the packer device.  
         [0005]     The desirable requirements for a large diameter packer system are typically at odds with those for a conduit pass-through system. U.S. Pat. No. 6,220,362, issued to Roth et al. describes a pass-through conduit arrangement for a packer assembly or other tool. The Roth patent is owned by the assignee of the present invention and is incorporated herein by reference. Roth describes a system wherein one or more axial conduit passages are formed through an interior portion of a packer or other tool. Roth teaches that there be complete pressure isolation between the conduit and both the tubing and the annulus. However, Roth describes the use of a separate carrier 60 that lies radially within the tool mandrel 24 and is used to define the longitudinal passages for the conduits or cables. The potential exists for improper sealing between the carrier and mandrel during fabrication of the tool, leading to undesirable fluid entry into the longitudinal passages. Additionally, this design does not offer any means for radial communication of fluid outwardly from the flowbore of the tool to the radial exterior of the tool. In fact, the requirement that the longitudinal passages remain isolated from fluid pressure from the flowbore, as well as the annulus, dictates against penetration of the carrier and/or mandrel by a radial fluid communication passage. If the carrier and mandrel of this tool were perforated to allow radial fluid communication, the passages defined therebetween would undesirably become exposed to external wellbore fluid pressures.  
         [0006]     To the inventor&#39;s knowledge, conduit feed through systems have not been successfully integrated into hydrostatically-set packer assemblies. It is believed that this failure is due to the complexity of a hydrostatic setting mechanism and the need for such a device to communicate hydrostatic fluid pressure through the inner mandrel of the packer assembly and into a chamber within the exterior portion of the packer assembly. The use of multiple interior pieces, such as a separate carrier and mandrel, to define a longitudinal cable/conduit pass-through, and the attendant assembly requirements, also adds to the difficulty of incorporating a cable feed-through feature into a hydrostatically-set device.  
         [0007]     U.S. Pat. No. 6,842,315 issued to Coronado et al., describes a hydrostatically-set packer device having a composite sealing element with large radial expansion capabilities for use in through tubing and open hole applications. This patent is owned by the assignee of the present invention and is, therefore, incorporated by reference. The device of the &#39;315 patent provides no feed-through arrangement for cables or conduits to be passed longitudinally through the packer device.  
         [0008]     The present invention addresses the problems of the prior art.  
       SUMMARY OF THE INVENTION  
       [0009]     The invention provides devices and methods for axially disposing electric, hydraulic and/or optical cables or conduits through the inner mandrel of a hydrostatically-set packer mechanism. In accordance with the devices and methods of the present invention, radial fluid communication is also provided through the inner mandrel so that the packer mechanism may be set using hydrostatic pressure within the flowbore. The axial feed-through path(s) for the cables or conduits are isolated from flowbore and annular fluid pressure. Additionally, the cables/conduits are protected from axial tensile forces and torsional forces that might damage them. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIGS. 1A-1C  present a side, cross-sectional view of an exemplary packer assembly with conduit feed through system constructed in accordance with the present invention.  
         [0011]      FIG. 2  is an axial cross-section taken along lines  2 - 2  in  FIG. 1C .  
         [0012]      FIG. 3  is an axial cross-section taken along lines  3 - 3  in  FIG. 1C .  
         [0013]      FIGS. 4A-4C  present a side, cross-sectional view of the packer assembly shown in  FIGS. 1A-1C , now with the packer element having been set. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]      FIGS. 1A-1C ,  2 , and  3  illustrate an exemplary hydrostatically-set packer assembly  10  that is constructed in accordance with the present invention. The packer assembly  10  includes a central mandrel  12  having an upper threaded end  14  which allows the packer assembly  10  to be incorporated into a production tubing string. The central mandrel  12  defines a central axial flowbore  16  along its length. A cable feed through path, generally designated as  18 , passes through the central mandrel  12 . Beginning at the upper end of the packer assembly  10 , the central mandrel  12  features a radially enlarged upper portion  20  with outer threads  22 . Below the enlarged upper portion  20  is a radially reduced mandrel portion  24 . At the lower end of the radially reduced portion  24  is a lower radially enlarged portion  26 . The enlarged portion  26  also defines an enlarged bore portion  27  within. The lower portion  26  presents an outwardly projecting shoulder  28  and a threaded connection  30  to a lower end sub  32 . The lower end sub  32  includes a set of interfitting longitudinal anti-rotation splines  34  and an axial cable passage  36 . The splines  34  engage complimentary splines  35  formed on the outside of the central mandrel  12 . Below the cable passage  36  is a lateral cable opening  38 .  
         [0015]     In a currently preferred embodiment, the feed-though path  18  includes an axially-oriented longitudinal central portion  40  and an upper angled end portion  42  that extends from the upper end of the central portion  40  radially outwardly to an axial upper end passage  44 . The axial upper end passage  44  includes an enlarged bore  46  that is shaped and sized to accommodate end nut  48 . The lower end of the central portion  40  interconnects to a lower angled end portion  50  that extends radially outwardly to an axially-oriented lower portion  52 . The lower end of the lower portion  52  also has an enlarged bore  54  that is shaped and sized to accommodate an end nut  56 . It is noted that the feed-through path  18 , and all of its individual components  40 ,  42 ,  50 ,  52 , are preferably constructed by drilling of suitably sized holes or passages through the central mandrel  12 . The component portions  40 ,  42 ,  50 ,  52  should interconnect with one another axially to provide a continuous path. An exemplary cable  58  is shown disposed within the feed-through path  18  and secured therewithin by end nuts  48 ,  56 . It can be seen that a portion  60  of the cable  58  extends upwardly toward the entry of the wellbore (not shown) while another portion  62  of the cable  58  extends downwardly toward a location below the packer assembly  10 . Thus, the cable feed-through path  18  allows communication through the packer assembly  10  to a device (not shown) that is located below the packer assembly  10 . It is noted that the term “cable,” is used herein to refer to an electrical cable, a hydraulic fluid conduit, a fiber optic cable, or any other type of tubular structure that is used to transmit fluid, power or communications into or out of a wellbore.  
         [0016]     The enlarged bore portion  27  of the central mandrel  12  accommodates an actuating sleeve  62  and an internal guide sleeve  64 . The guide sleeve  64  provides a radially exterior surface  66  that defines the inner boundary of the lateral cable opening  38 . Additionally, the guide sleeve  64  presents an inner surface  68  with an upper radially is enlarged bore portion  70 . The actuating sleeve  62  presents an inner surface  72  that extends radially inwardly of the enlarged bore  70 , thereby creating an engagement shoulder  74  at the lower end of the sleeve  62 . The outer radial surface  76  of the actuating sleeve  62  carries a number of annular fluid seals  78 , a dog recess  80  and a locking ring  79 . It is noted that the actuating sleeve  62  is axially moveable between a lower position, shown in  FIG. 1 , wherein the lower end of the sleeve  62  contacts the guide sleeve  64 , and an upper position, shown in  FIG. 2 , wherein the upper end  82  of the actuating sleeve  62  contacts an internal stop shoulder  84  of the central mandrel  12 . Frangible shear screws  82  pass through the body of the central mandrel  12  and into the actuating sleeve  62  to initially secure the actuating sleeve  62  in its lower position.  
         [0017]     A plurality of radial fluid communication ports  88  also pass through the central mandrel  12  to provide fluid communication between the internal flowbore  16  of the mandrel  12  and its radial exterior. As  FIG. 2  illustrates, the shear screws  82  are angularly offset from each of the fluid ports  88  about the circumference of the central mandrel  12 . Fluid flow through the fluid ports  88  is initially blocked by the presence of the actuating sleeve  62  and fluid seals  78 .  
         [0018]     Beginning once again proximate the upper end of the packer assembly  10 , a second set of longitudinal anti-rotation splines  90  are defined upon the central mandrel body  12 . Splines  90  interfit with complimentary anti-rotation splines  92  on the central mandrel  12 . The interfitting of the splines  90 ,  92  prevents rotation of the central mandrel  12  components with respect to one another.  
         [0019]     The ring  98  is retained in place upon the outer surface of the central mandrel  12  by a housing sub  100  that is secured to the central mandrel  12  by threaded connection  22 . An annular space  102  is defined between the lower end of the housing sub  100  and the outer surface of the central mandrel  12 . Ring  104  is secured to the lower end of the housing sub  100  at threaded connection  106 . The ring  104  provides tensioning portions  105 , of a type known in the art, for exerting a tensioning force upon the packer element  110 .  
         [0020]     An upper end setting sleeve  108  also surrounds the central mandrel  12  below the ring  104 . The setting sleeve  108  is used to help set the packer element  110  that lies immediately below it on the radial exterior of the central mandrel  12 . During setting of the packer assembly  10 , the upper end setting sleeve  108  remains stationary with respect to the central mandrel  12 . The upper end setting sleeve  108  has a retainer portion  112  that extends over a portion of the packer element  110 . A lower end setting sleeve  114  is located at the lower end of the packer element  110  and also presents a retainer portion  116  that extends over a portion of the packer element  110 .  
         [0021]     The packer element  110  is preferably a composite packer element as described in U.S. Pat. No. 6,843,315, issued to Coronado et al. This patent is owned by the assignee of the present invention and is herein incorporated by reference. This type of packer element is suitable for use in creating a fluid seal in larger bores and even uncased borehole sections. Below the lower end setting sleeve  114  is a setting, or actuating, assembly, generally shown at  118 , having an upper sub  120  with fluid fill port  122 , a setting assembly housing  124  and a lower sub  126 . The setting assembly housing  124  encases an atmospheric chamber  128 . The atmospheric chamber  128  is bounded at axial ends by the upper and lower subs  120 ,  126 . When the piston assembly  10  is in the unset position (shown in  FIG. 1 ), the atmospheric chamber  128  is at atmospheric pressure.  
         [0022]     An actuating piston, generally shown at  130 , is retained within the atmospheric chamber  128 . The actuating piston  130  is made up of a lower piston ring  132 , central ring  134 , and an upper piston ring  136 , these components being affixed to one another by threaded connections  138 ,  140 . The lower piston ring  132  presents a fluid pressure receiving area  142 . Additionally, the lower piston ring  132  has an annular dog recess  144  inscribed upon its inner surface. Elastomeric O-ring seals  146  are used to provide fluid sealing between the actuating piston  130  and the chamber  128 . The upper end of the upper piston ring  136  is secured by threaded connection  148  to a body lock ring assembly  150 . The body lock ring assembly  150  includes a locking ring  152  with an inner ratchet surface  154 . The ratchet surface  154  is formed to interengage with outwardly-facing ratchet surface  156  on central mandrel  12 . Packer element setting member  158  is affixed to the body lock ring assembly  150  and presents an enlarged setting portion  160  that abuts the lower end of the packer element  110 .  
         [0023]     A locking dog  162  initially secures the actuating piston  130  and the central mandrel  12  together. In the unset position, shown in  FIG. 1 , the dog  162  resides within a dog passage  164  that is disposed radially through the central mandrel  12 . A portion of the dog  162  extends outwardly into dog recess  144  in the actuating piston  130 . Movement of the dog  162  radially inwardly is blocked by the presence of actuating sleeve  62 . It is noted that the dog  162  and all shear screws  82  are radially offset from the cable feed-through path(s)  18  so that the feed-through path(s)  18  remain unexposed to fluid ingress and wellbore pressures. This arrangement is best shown in  FIGS. 2 and 3 .  
         [0024]     Hydrostatic forces are used to set the packer device  10 .  FIGS. 4A-4C  show the packer device  10  in a set condition. When it is desired to set the packer assembly  10 , a shifting tool (not shown), of a type known in the art, is disposed into the flowbore  16  of the central mandrel  12 . The shifting tool contacts the engagement shoulder  74  of the actuating sleeve  62  and moves the actuating sleeve  62  axially upwardly. This movement will shear the shear screws  82  and unblock fluid communication ports  88 . The locking ring  79  secures into a mating recess in the central mandrel  12  (see  FIG. 4C ) to secure the actuating sleeve  62  in the upward position. Additionally, upward movement of the actuating sleeve  62  will bring the dog recess  80  into general alignment with the locking dog  162 . The dog  162  is moved radially inwardly to reside partially within the recess  80  and is thus moved out of the outer dog recess  144 . This unlocks the actuating piston  130  from engagement with the central mandrel  12 . As upward movement of the actuating sleeve  62  unblocks the fluid ports  88 , hydrostatic fluid pressure present within the flowbore  16  will then be transmitted through the ports  88  and enter the pressure receiving area  142 . Wellbore hydrostatic pressure will bear upon the pressure receiving area  142  of the actuation piston  130  and urge the piston  130  axially upwardly. The packer element setting member  158  will compress the packer element  110  axially to cause it to expand radially and become set.  
         [0025]     It can be seen that the arrangement of the present invention provides a means for disposing one or more cables axially through a hydrostatically-set packer device while also permitting radial fluid communication through the central mandrel. The feed-through paths  18  of the packer assembly  10  desirably isolate the cables from fluid pressure present in either the flowbore  16  or the annulus surrounding the packer device  10 . Because the feed-through paths  18  are angularly offset from the fluid communication ports  88  about the circumference of the central mandrel  12 , fluid pressure being communicated radially through the mandrel  12  will not enter the feed-through paths  18 .  
         [0026]     Cables extending through the feed-through paths  18  are also protected from axial tensional forces that would be exerted upon the packer assembly  10  as it is being used as well as torsional forces that might be experienced as the packer assembly  10  is being made up or run in the well. The cables are retained in place within the feed-through path(s)  18  by end nuts  48 ,  56 , which secure them to the central mandrel  12 .  
         [0027]     Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.