Abstract:
A wellhead assembly has an electrical connector that has a movable inner member carried in a tubing hanger for stroking outward into engagement with an stationary outer component located in a passage in the sidewall of the wellhead or tree. A running tool releasably engages the tubing hanger and has an actuator that moves axially for setting the tubing hanger in the bore. The inner member of the electrical connection is movable in response to axial movement of the actuator of the running tool from a retracted position to an extended position in electrical engagement with the inner end of the outer member.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority to provisional application Ser. No. 60/418,582, filed Oct. 15, 2002. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates in general to subsea electrical connectors and in particular to a connector for connecting electrical power to a subsea Christmas tree.  
       BACKGROUND OF THE INVENTION  
       [0003]     One type of subsea well has a Christmas tree located on the sea floor. The tree mounts on a wellhead at the upper end of the well and has valves for controlling the well fluid. The well fluid flows upward through a string of production tubing that is suspended by a tubing hanger. In one type of subsea tree, the tubing hanger lands in the tree.  
         [0004]     Downhole temperature and pressure are useful parameters to monitor. This normally requires pressure and temperature sensors located at the lower end of the string of tubing. An electrical wire extends alongside the tubing to the tubing hanger. This wire connects to an exterior wire that supplies voltage and monitors the pressure and temperature. The connector between the interior and the exterior wires may be located at various interfaces of the tree. One type of connector has a laterally movable shuttle member mounted in the sidewall of the tree that is remotely actuated to move into engagement with an electrical contact in the tubing hanger at the upper end of the interior wire. Electrical wires leading downhole are also needed for other purposes, such as for powering an electrical submersible pump.  
       SUMMARY OF THE INVENTION  
       [0005]     The wellhead assembly of this invention is for use with an outer wellhead member mounted to an upper end of a well. The outer wellhead member has a sidewall defining a bore. An inner wellhead member lands in the bore. An electrical connection outer member is mounted in a passage formed in the sidewall. The outer member of the electrical connection has an inner end and an outer end, the outer end being connected to an exterior electrical conductor on the exterior of the outer wellhead member.  
         [0006]     An electrical connection inner member is mounted to the inner wellhead member and connected to an interior electrical conductor leading to equipment in the well. The inner member has an outer end that is movable from a retracted position to an extended position in electrical engagement with the inner end of the outer member.  
         [0007]     Preferably a lateral actuator member is located at an inner end of the inner member. The lateral member is laterally movable relative to an axis of the inner wellhead member for moving the inner member from the retracted position. An axial actuator member extends axially upward from the lateral actuator member, so that axial movement of the axial actuator member causes the lateral actuator member to move laterally.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The novel features believed to be characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings.  
         [0009]      FIG. 1  is a cross-sectional side view of a tubing hanger landed within a horizontal tree, the tubing hanger and tree having wet-mate connectors according to the invention, the left side of the figure showing a tubing hanger locking sleeve and the connector in a disengaged position, the right side of the figure showing the locking sleeve in an engaged position.  
         [0010]      FIG. 2  is an exploded isometric view of the tubing hanger connector of  FIG. 1 .  
         [0011]      FIG. 3  is an enlarged cross-sectional side view of the connector of  FIG. 1 , the connector being in the disengaged position and positioned adjacent a female connector installed in the tree.  
         [0012]      FIG. 4  is a cross-sectional side view of an alternate embodiment of the connector of the invention, the view showing the connector in a disengaged position.  
         [0013]      FIG. 5  is a cross-sectional side view of the embodiment of  FIG. 4 , the connector being shown in an engaged and locked position.  
         [0014]      FIG. 6  is a perspective view of a lock used to retain the tree connector of  FIG. 1 .  
         [0015]      FIG. 7  is an enlarged view of a section of the lock of  FIG. 6 , a portion of the lock being removed.  
         [0016]      FIG. 8  is an enlarged cross-sectional view of the tree connector of  FIG. 1 , the lock of  FIG. 6  retaining the lock in the tree.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]      FIG. 1  shows a tubing hanger  11  landed within a horizontal tree  13 , each being concentric about a vertical central axis  14 . A running tool  15  has a piston  16  that reciprocates vertically for setting a locking sleeve  17 , sleeve  17  being used for locking hanger  11  in tree  13 . A lower portion of piston  16  contacts an upper portion of sleeve  17  and exerts a downward force to move sleeve  17  from an upper, disengaged position, which is shown in the left half of  FIG. 1 , to a lower, engaged position, which is shown in the right half of the figure. A seal  18  is installed in an upper portion of sleeve  17  and a cylindrical skirt  19  depends from a lower portion of sleeve  17 . Skirt  19  has a cam surface  21  for moving dogs  23  outward (away from central axis  14 ) when sleeve  17  is moved to the engaged position. Dogs  23  are moveably carried in hanger  11  and have a groove profile  25  on an outer surface for engaging a corresponding groove profile  27  in bore  29  of tree  13  when dogs  23  are moved outward. Hanger  11  lands on an upward-facing shoulder (not shown) in bore  29 , which supports hanger  11  and prevents downward movement of hanger  11  within tree  13 . Dogs  23  engage tree  13 , as shown in the right side of the figure, to prevent upward movement of hanger  11  within tree  13 .  
         [0018]     An electrical connector  31  is installed in the sidewall of hanger  11  prior to hanger  11  being landed in tree  13 . Connector  31  is shown in the disengaged position in the left side of  FIG. 1 . As running tool  15  forces sleeve  17  downward, a lower portion of sleeve  17  contacts an upper end  33  of a rod  35 , rod  35  being reciprocatingly and vertically carried within hanger  11 . The lower end of rod  33  is connected to a male block  37  that engages a female block  39 , which is reciprocatingly and horizontally carried within cavity  41  in hanger  11 . A conductor pin  43  extends from the outer surface of block  39  and is entirely recessed within cavity  41  when connector  31  is in the disengaged position. This positioning of pin  43  permits hanger  11  to be lowered into tree  13  without damaging pin  43 .  
         [0019]      FIG. 2  is an exploded isometric view of the components of connector  31 . The lower end of rod  35  is sized for insertion into a hole  45  in upper surface  47  of male block  37 . Inclined rails  49  are located on opposite lateral sides of block  37  for engaging corresponding grooves  51  in female block  39 . As rod  35  moves block  37  downward, rails  49  enter and slide within grooves  51 , and inclined surface  53  of block  37  slides against corresponding inclined surface  55  located between grooves  51 . Downward force passes from sleeve  17  through rod  35 , into block  37 , and from surface  53  of block  37  to surface  55  of block  39 , the downward vertical motion of rod  35  and block  37  causing outward horizontal motion of block  39 . When sleeve  17  is lifted, such as during retrieval of hanger  11 , upper edges  57  of rails  49  slide against upper surfaces  59  of grooves  51  for moving block  39  inward (toward central axis  14  of  FIG. 1 ) as rod  35  moves block  37  upward.  
         [0020]     A pin mount  61  comprises the outer end of block  39 , inner surface  63  mounting to outer surface  65  of block  39 . Pin  43  extends from outer surface  67  of pin mount  61 , and connector  69  provides for connecting an electrical cable  70  ( FIG. 1 ) to conduct electricity from pin  43  to downhole components supported by hanger  11 .  
         [0021]     Like  FIG. 1 ,  FIG. 3  also shows connector  31  in the disengaged position. Sleeve  17  ( FIG. 1 ) is initially spaced a selected distance from the upper end of rod  35 , sleeve  17  moving downward for the selected distance before contacting rod  35 , thereby limiting the movement of rod  35  to only a portion of the total movement of sleeve  17 . In the disengaged position, lock surface  71  of block  37  engages lock surface  72  of block  39 , preventing block  39  from moving outward. As rod  35  moves downward, lock surface  71  moves below lock surface  72 , and block  37  causes block  39  to move outward (to the left in the figure) until surface  55  of block  39  moves from under surface  53  of block  37 . At this point, block  37  continues moving downward as block  39  remains stationary, with lock surface  73  of block  37  sliding adjacent lock surface  74  of block  39 . This positioning locks block  39  in the outward position. To complete installation of hanger  11 , piston  16  of running tool  15  is lifted, and locking sleeve  17  remains in the downward position as running tool  15  is withdrawn. Sleeve  17  retains rod  35  and block  37  in their downward positions, locking block  39  in its outward position to move pin  43  into engagement with a female connector  75  in tree  13 .  
         [0022]     Referring to  FIG. 3 , a female wet-mate connector  75  is mounted in the sidewall of tree  13  for receiving pin  43  of connector  31 , and hanger  11  is landed in tree  13  with connector  31  vertically and rotationally aligned with connector  75 . Lock  76 , shown in  FIGS. 6 through 8  and described below, retains connector  75  within tree  13 . Connector  75  may be of various types. In this embodiment, connector  75  is mounted with inner seal  77  approximately flush with bore  29 , with inner seal  77  adjacent an outer seal  79  in cavity  41 . Pin  43  passes through outer seal  79  as block  39  moves outward, and then pin  43  passes through inner seal  77  into receptacle  81  of conductor assembly  83 . Receptacle  81  and conductor assembly  83  are formed from an electrically conductive material for conducting electricity from electrical cable  85  through conductor assembly  83  to pin  43 . The electricity passes through pin  43  to cable  70  to power downhole components (not shown). Though shown with connectors  31 ,  75  in  FIGS. 1 through 3 , the connectors may be of various wet-mate types, for example, the connectors of the alternative embodiment of the invention shown in  FIGS. 4 and 5 . A flexible bladder  86  surrounds receptacle  83  and is filled with a dielectric gel. The exterior of bladder  86  is exposed to hydrostatic pressure within bore  29  of tree  13  that exists prior to running tubing hanger  11 .  
         [0023]     Referring to  FIGS. 1 through 3 , during installation of tubing hanger  11 , female wet-mate connector  75  is connected to electrical cable  85  and installed with lock  76  in horizontal tree  13 . Tree  13  is then installed at a subsea wellhead. Connector  31  is installed in cavity  41  of hanger  11  and connected to electrical cable  70 , and rod  35  is installed in hanger  11  with the lower end of rod  35  inserted in male block  37 . Outer seal  79  engages the outer end of pin  43  to prevent water or other contaminants from entering cavity  41 . A locking sleeve  17  on hanger  11  is held in an upper position, dogs  23  and block  39  of connector  31  being in inner, disengaged positions. Hanger  11  is lowered with a running tool  15  into bore  29  of tree  13  and landed on a shoulder (not shown) in bore  29 . Piston  16  of running tool  15  moves locking sleeve  17  downward, and cam surface  21  of skirt  19  forces dogs  23  outward to engage profile  27  of tree  13 . After sleeve  17  travels downward a selected distance, skirt  19  contacts upper end  33  of rod  35 , rod  35  then moving downward with sleeve  17 . Rod  35  pushes block  37  downward and into contact with female block  39 , rails  49  of block  37  sliding in grooves  51  of block  39 . Surface  53  of block  37  applies force to and slides against surface  55  of block  39 , block  39  moving outward as block  37  moves downward. Block  39  moves outward until surface  73  slides adjacent surface  74  to lock block  39  in the outer position. Pin  43  moves through outer seal  79  at the outer end of cavity  41  and enters connector  75  through inner seal  77 . Pin  43  extends into receptacle  81 , forming an electrical connection between cable  85  and cable  70  through connectors  75 ,  31 . Installation of hanger  11  is completed by lifting piston  16  of running tool and retrieving running tool.  
         [0024]     To remove hanger  11 , running tool  15  is lowered to the subsea installation and into engagement with tree  13  and hanger  11 . Piston  16  lifts locking sleeve  17 , allowing dogs  23  to move inward out of engagement with tree  13 . As sleeve  17  moves upward, rod  35  and block  37  also move upward. Upper surfaces  57  of rails  49  slide against surfaces  59  of grooves  51  for causing block  39  to move inward, pin  43  moving out of engagement with connector  75 . Hanger  11  can then be retrieved from within bore  29 .  
         [0025]     An alternate embodiment of the invention is shown in  FIGS. 4 and 5 , with similar numbers corresponding to the numbers of similar components in the embodiment of  FIGS. 1 through 3 . Tubing hanger  11  is shown landed within horizontal tree  13 . Prior to installation of hanger  11 , male connector  131  is installed within hanger  11 , connector  131  comprising rod  135 , male block  137  and female block  139 . Blocks  137 ,  139  interact in the manner as blocks  37 ,  39  in the embodiment described above. Rod  135  is forced downward by sleeve  17  ( FIG. 1 ), pushing block  137  downward and into engagement with block  139 . Rails  149  of block  137  enter and slide within grooves  151  of block  139 , and surface  153  contacts and slides against surface  155 . As block  137  moves downward, rails  149  and surface  153  causes block  139  to move outward toward a female connector  175  installed in tree  13 .  FIG. 4  shows block  139  in the disengaged position, and  FIG. 5  shows block  139  in the engaged and locked position. In the disengaged position, lock surface  171  of block  137  engages lock surface  172  of block  139  for preventing block  139  from moving outward. In the engaged position, lock surface  173  of block  137  contacts lock surface  174  of block  139  for preventing block  139  from moving inward.  
         [0026]     Pin mount  161 , from which tubular pin  143  extends outward, comprises the outer end of block  139 . Pin  143  has a tubular body  187  that encloses a receptacle  189 , receptacle  189  having a chamfered outer opening  191  for guiding a corresponding pin within connector  175  into receptacle  189 . Receptacle  189  is connected to electrical cable  170  for conducting electricity from connector  175  through receptacle  189  and down cable  170  to downhole components.  
         [0027]     Connector  175  is installed in tree  13  prior to installation of tree  13  at a subsea location. As hanger  11  is landed within tree  13 , connectors  131 ,  175  are vertically and rotationally aligned, allowing for pin  143  to engage connector  175  as block  139  moves outward. An elastomeric, ring-shaped piston  193  is movably carried within a bore  194  in connector  175 , pin  143  of connector  131  contacting piston  193  for moving piston  193  outward with pin  143 . The diameter of bore  194  is sized to receive the outer diameter of body  187  of pin  143 . Piston  193  is biased toward bore  29  of tree  13  by springs  195 , and retaining ring  196  provides an inward stop for piston  193 . A pin  197  extends inward from the outer end of bore  194  and through the central portion of piston  193 , piston  193  sealingly engaging the surface of pin  197 . Pin  197  comprises a conductive portion  198  and a non-conductive portion  199 , portion  198  forming the inner end of pin  197 . Pin  197  is sized for insertion into receptacle  189  of pin  143  and is connected to electrical cable  185  at the outer end for conducting electricity from a source to pin  197 .  
         [0028]     During installation of hanger  11 , connector  175  is installed in tree  13 , which is then installed at a subsea well. Connector  131  is installed in hanger  11 , and then hanger  11  is landed within tree  13  using a running tool  15  ( FIG. 1 ). Running tool  15  forces a locking sleeve  17  ( FIG. 1 ) downward, which causes rod  135  to move downward. Rod  135  forces block  137  downward, with rails  149  engaging grooves  151  and surfaces  153 ,  155  sliding against each other, causing block  139  to move outward. As pin  143  of connector  131  moves outward toward the engaged position, which is shown in  FIG. 5 , pin  143  first contacts piston  193  and begins forcing piston  193  outward. This movement moves piston  193  outward through bore  194  and compresses springs  195 . Pin  143  enters bore  194  of connector  175  as pin  197  of connector  175  enters receptacle  189 . Prior to engagement, piston  193  seals against the inner end of conductive portion  198  of pin  197 . As piston  193  moves inward, conductive portion  199  contacts the inside surface of receptacle  189 , providing a conductive path from cable  185 , through pin  197 , into receptacle  189 , and out through cable  170 .  
         [0029]     To allow for subsea installation and removal of connector  75  ( FIG. 3 ) using a remotely operated vehicle (ROV), lock  76  is used to retain connector  75  within the sidewall of tree  13 .  FIG. 6  shows lock  76  assembled and read for installation. Lock  76  comprises two opposing clamp sections  201 ,  203 , each having an internal recess  205  for forming outer lips  207  and inner lips  209 . Clamp sections  201 ,  203  are pivotally connected to each other at hinge  211 , and a bolt (not shown) is inserted through hole  213  in hinge  211  for mounting lock  76  on an exterior surface of tree  13 . A wedge member  215  moveably engages ends of clamp sections  201 ,  203  opposite hinge  211  with ramps  217  formed on surface  219  of wedge member  215 . Ramps  217  lie at an angle relative to a plane bisecting hinge  211  and wedge member  215  and engage corresponding slots  221  ( FIG. 7 ) on clamp sections  201 ,  203 . A threaded shaft  223  threadingly engages wedge member  215 , shaft  223  being rotated by an ROV at a hub  225  on an outer end of shaft  223 .  FIG. 7  is a view of the ends of clamp sections  201 ,  203 , wedge member  215  having been removed to show slots  221 . Slots  221  are formed to have the same angle as ramps  217  ( FIG. 6 ) and are sized to receive ramps  217 .  
         [0030]     Referring to  FIGS. 6 and 7 , in operation, as shaft  223  is rotated to move wedge member  215  outward (toward hub  225 ) along shaft  223 , ramps  217  slide within slots  221 , pivoting clamp sections  201 ,  203  about hinge  211  and spreading apart the ends of sections  201 ,  203  to open lock  76 . This creates a larger gap between faces  227 ,  229  of sections  201 ,  203 , respectively. As shaft  223  is rotated to move wedge member  215  inward, ramps  217  cause clamp sections  201 ,  203  to pivot toward each other, closing lock  76  and reducing the gap between faces  227 ,  229 .  
         [0031]      FIG. 8  shows connector  75  installed in tree  13 . Connector  75  is installed in connector housing  231 , the inner end of which is then inserted into bore  233 . A flange  235  is formed around bore  233 , and a flange  237  is formed on connector housing  231 , flanges  235 ,  237  having approximately the same outer diameter. During installation, lock  76  is opened, as described above, and clamp sections  201 ,  203  are positioned around flanges  235 ,  237 . Lock  76  is then closed, with flanges  235 ,  237  being located in recess  205  and lips  207 ,  209  securing flanges  235 ,  237  together. Connector housing  231  is thus retained within bore  233  of tree  13 , and connector  75  is located for engagement by connector  31  ( FIG. 1 ).  
         [0032]     Several advantages are realized from the present invention. A wet-mate connector and the actuating mechanism for engaging the connector are carried in the tubing hanger, which is easily retrieved for maintenance or repair. The connector is actuated when the piston of the running tool moves the locking sleeve of the tubing hanger into place, obviating the need for additional actuating components required for a connector carried in the tree. Additionally, the connector in the hanger is locked in position when the actuating mechanism passes through its full travel. A lock operable by an ROV retains the connector in the tree, allowing for removal and installation of the connector without having to retrieve the tree from a subsea location.  
         [0033]     While the invention has been described in only one of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention. For example, the conductor pin in the tubing hanger could alternately be stroked inward and outward by a hydraulic piston. The piston could be supplied with hydraulic pressure by the running tool for the tubing hanger.