Abstract:
A connector for connecting electrical power to a well pump motor has cable and motor connector portions that mate with each other in a connected position. The connector portions have insulating members, each of which has a number of passages and an end face. Electrical contact members are mounted in each of the passages. Contact members in the cable connector portion protrude past the end face of the insulating member. A debris seal insulates the electrical contact members in the cable connector and includes expansion slots so that when the material of the debris seal thermally expands, the expansion slots contract in response to the expansion without the debris seal impinging against either connector.

Description:
1. FIELD OF THE INVENTION 
       [0001]    This invention relates in general to downhole electrical connectors for use in electrical submersible pump applications, and in particular to a downhole pothead connector for use in oil wells. 
       2. BACKGROUND OF THE INVENTION 
       [0002]    Electrical submersible pumps have been used in oil wells to pump well fluids for many years. These pumps are part of an assembly that includes a submersible motor. The pump assembly is typically suspended on tubing, and a power cable from the surface is strapped alongside the tubing. A motor lead is secured to the lower end of the power cable, the motor lead terminating in a connector that plugs into a receptacle of the motor. This connector is typically known as a pothead connector. 
         [0003]    The motor is filled with a dielectric lubricant that is sealed from the exterior at the receptacle. The connector has seals that seal the electrical conductors from well fluid. A variety of connectors are known. In one type, the cable portion of the connector has a housing that contains two rigid insulating members separated by a deformable insulating member. Passages extend through the members for sealingly receiving the insulated electrical conductors. Electrical contact members or pins connect to the conductors and protrude past the forward insulating member. The remaining portion of the housing is filled with an epoxy. 
         [0004]    The receptacle portion of the connector has a rigid insulating member with passages for receiving insulated conductors from the motor. Electrical contact members, typically sleeves, are located in the passages in the insulating member. When the cable portion of the connector is connected to the receptacle, the electrical contact pins slide into the electrical contact sleeves. If the motor lubricant becomes contaminated, debris from the oil can encroach into the connector and come into contact with the electrical contact members. The debris can cause electrical arcing in this region. A debris seal is generally included for isolating the sleeves (or pin connections) from debris and to provide dielectric strength between the pins and each pin and ground. Temperature increases in the wellbore may thermally expand the debris seal, that in turn can press outward against the connector assembly and increase internal pressure of the assembly. 
       SUMMARY 
       [0005]    Disclosed herein is a submersible well pump assembly, in an example embodiment the submersible well pump assembly includes a submersible electrical motor that has an electrical motor lead so it can be connected to a power cable. The motor lead has male and female connector portions, one of which is connected to the motor lead and the other to the motor. When the motor lead is in a connected position the connector portions are mated to one another. The male and female connector portions each have a plurality of passages and an end face; each male connector has a plurality of male electrical contact members mounted therein that protrude past the end face of the male connector and into each of the passages. The female connector has within each of its passages a plurality of female electrical contact members mounted and recessed therein. Further included is an elastomeric debris seal on the end face of the male connector portion; the debris seal has an insulating barrier with a plurality of bores circumscribing one of the male electrical contact members. The debris seal also includes at least one thermal expansion slot in the barrier that is spaced from each of the bores. Alternatively, the expansion slot extends from an outer periphery of the debris seal towards a center of the debris seal. In an example embodiment, the expansion slot is between a center of the debris seal and an outer periphery of the debris seal and spaced from the outer periphery of the debris seal. The debris seal can expand in response to an increase in temperature and into the expansion slot so that a contact force between the debris seal and the faces is substantially constant during the increase in temperature. In optional embodiments, the expansion slot has a curved outer periphery, can be generally elongate, or can be a plurality of expansion slots formed through the debris seal. Yet further optionally, the debris seal can be set at angular positions with respect to a center of the debris seal and each other, and are offset from angular positions of the bores. In this option, the expansion slots can be equidistant apart and located on the debris seal at angular positions with respect to a center of the debris seal or can be located on the debris seal at angular positions with respect to a center of the debris seal that are aligned with angular positions of the bores. 
         [0006]    Disclosed herein is an example embodiment of a submersible well pump assembly that is made up of a submersible electrical motor having an electrical motor lead that enables connection to a power cable. The assembly of this embodiment also includes a cable end housing to facilitate connection to the motor lead. In the housing is a cable insulating member made of an insulating material, a plurality of passages is formed through the insulating member. In the passages are a plurality of electrical conducting cable contact members that are joined to the motor lead. Each cable contact member protrudes past an end face of the cable insulating member. A motor insulating member of insulating material is included that mounts in a receptacle of the electrical motor. The motor insulating member has an end face and passages extending through the motor insulating member. A plurality of electrical conducting motor contact members are provided in each one of the passages of the motor insulating member, the contact members are engaged by the cable contact member when the cable end housing and the receptacle are in a connected position. Further included is a debris seal on the end face of the cable insulating member, in an example embodiment the debris seal is an elastomeric insulating disc having a plurality of bores each circumscribing one of the cable contact members, and a plurality of thermal expansion slots in the barrier that are spaced from each of the bores. Expansion slots may be located on the debris seal at angular positions with respect to a center of the debris seal that are offset from angular positions of the bores. The debris seal can expand in response to an increase in temperature and wherein substantially all of the expansion is directed into the expansion slot so that a contact force between the debris seal and the faces is substantially constant during the increase in temperature. Each expansion slot can have a curved outer periphery or be generally elongate. The debris seal can be a generally planar member set generally perpendicular to the cable contact members. In an example embodiment, the expansion slot is between a center of the debris seal and an outer periphery of the debris seal and spaced from the outer periphery of the debris seal. 
         [0007]    Also disclosed herein is a submersible well pump assembly; in an example embodiment the submersible well pump assembly has a submersible electrical motor connectable to a power cable by an electrical motor lead. A cable end housing is on the power cable for connection to the motor lead, in the housing is a cable insulating member of insulating material with passages formed therethrough. Cable contact members are mounted in each passage of the cable insulating member and joined to the motor lead. Each cable contact member protrudes past an end face of the cable insulating member. Also included in a receptacle of the electrical motor is a motor insulating member of insulating material an end face and a plurality of passages therethrough. Each passage of the motor insulating member has a motor contact member that is engaged by the cable contact member when the cable end housing and the receptacle are in a connected position. A generally planar debris seal is provided on the end face of the cable insulating member. In an example embodiment, the debris seal is made of an elastomeric insulating disc having a plurality of bores each circumscribing one of the cable contact members and that expands in response to an increase in temperature and wherein substantially all of the expansion is directed into the expansion slot so that a contact force between the debris seal and the faces is substantially constant during the increase in temperature. The debris seal of this embodiment has thermal expansion slots in the barrier, each expansion slot spaced from each of the bores located on the debris seal at angular positions with respect to a center of the debris seal that are offset from angular positions of the bores. Optional embodiments include each expansion slot extending from an outer periphery of the debris seal towards a center of the debris seal or between a center of the debris seal and an outer periphery of the debris seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side view of an example of an electrical submersible pumping system (ESP) in a borehole in accordance with the present disclosure; 
           [0009]      FIG. 2  is a side view of an example of a pothead connector in accordance with the present disclosure; 
           [0010]      FIGS. 3A and 3B  are alternate embodiments of a debris seal for use with the pothead connector of  FIG. 2 ; 
           [0011]      FIG. 4  is a longitudinal sectional view and depicts the interior of the pothead connector of  FIG. 2  shown mounted to the terminal end of the flat downhole electric cable; 
           [0012]      FIG. 5  is a side view of the pothead connector of  FIG. 2  connecting to a female assembly; and 
           [0013]      FIG. 6  is a side sectional view showing the pothead connector and female assembly of  FIG. 5  connected to one another. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Shown in a side partial sectional view in  FIG. 1  is a wellbore  2  capped with a wellhead  3  and production tubing  4  depending from the wellhead  3  into the wellbore  2 . An electrical submersible pumping system (ESP)  5  is shown attached on a lower end of the production tubing  4 . In the example embodiment of  FIG. 1 , the ESP  5  includes a pump section  6  for pumping fluids from the wellbore  2  into the production tubing  4  and to the wellhead  3 . Fluid (not shown) in the wellbore  2  flows into the pump section  6  through an inlet  7  shown formed on an outer surface of the pump section  6 . On a lower end of the pump section  6  is a seal section  8  for equalizing pressure within the ESP  5  to ambient conditions. A motor section  9  is shown on a lower end of the seal section  8  that includes a motor (not shown) for driving impellers (not shown) in the pump section  6 . 
         [0015]    An elevational view of an embodiment of the pothead connector  10  of  FIG. 1  is provided in  FIG. 2 . The pothead connector  10  includes connectors  18  that project outward from within an annular base  17  shown set on a connector flange  11 . A circular debris seal  15  is shown set within the base  17  and disposed in a plane substantially perpendicular to the connectors  18 . Bores  16  are provided in the debris seal  15  for insertion of each connector  18  that closely encircle each connector  18 . The debris seal  15  insulates the connectors  18  from one another and from ground. The seal  15  should be able to maintain an, insulating function while experiencing operating temperatures that can sometimes exceed 350° F. The debris seal  15  can be manufactured from a polymeric material, such as for example a synthetic rubber or an ethylene propylene diene monomer. Expansion slots  19  are shown provided in the debris seal  15  at strategic locations; so that when the debris seal  15  temperature increases, the debris seal  15  material expands into the slots  19  instead of impinging upon the connector  10 . The presence of the expansion slots  19  provides a space in which the material of the seal  15  can expand instead of up against the connector  10 . The slots  19  of  FIG. 2  are symmetrically disposed around the circumference of the debris seal  15  and project inward towards the center of the debris seal  15  from its outer edge and have a curvilinear periphery resembling an end portion of an ellipse. In an example embodiment, the expansion slots  19  are at angular positions of the debris seal  15  equidistant between adjacent pins  18 . Optionally, the expansion slots  19  can be asymmetrically set around the periphery of the debris seal  15 . While three expansion slots  19  are illustrated in the example embodiment of  FIG. 2 , alternate embodiments of the debris seal  15  exist having one, two, or more than three slots  19 . In another alternative embodiment, expansion slots  19  may be set at generally the same angular position as the pins  18 . In an example embodiment, a series of expansion slots  19  may be formed along the entire periphery of the debris seal  15 . 
         [0016]    Shown in  FIGS. 3A and 3B  are alternate example embodiments of the debris seal  15  of  FIG. 2 . The expansion slots  19 A of the debris seal  15 A illustrated in  FIG. 3A  are elongate, where the elongate side projects into the debris seal  15 A from its edge. Referring to the example embodiment of  FIG. 3B , generally circular expansion slots  19 B are provided in the debris seal  15 B and set inward from its outer edge. The expansion slots  19 A,  19 B of  FIGS. 3A and 3B  are illustrated symmetrically positioned between bores  16 A,  16 B provided in the debris seals  15 A,  15 B. Bores  16 A,  16 B are similar to bores  16  and allow the pins  18  to pass therethrough. Alternative embodiments may asymmetrically position the expansion slots  19 A,  19 B within the debris seals  15 A,  15 B. 
         [0017]      FIG. 4  is a longitudinal section view and depicts the interior of the pothead connector  10  made according to an embodiment of the present invention, mounted to the terminal end of a motor lead  12 . The upper or rearward end of motor lead  12  is joined to an electrical cable extending to the surface of the well. Pothead connector  10  may have a wide variety of components. However, in this example, pothead connector  10  has a tubular housing  30  with a rearward end  32  through which cable  12  passes and a forward end  34  through which electrical conductor pins  18  extend. Pins  18  electrically connect to a female receptacle  14  of a down hole electrical submersible motor  9  ( FIG. 2 ). Tubular housing  30  preferably comprises two opposite end pieces, base  17  and cap  36 . Base  17  provides forward end  34 , and cap  36  provides rearward end  32 . 
         [0018]    Still referring to  FIG. 4 , cap  36  of tubular housing  30  has a tapered tubular end  38  which extends around the exterior of armor  40  of motor lead  12 . The interior of cap  36  is filled with epoxy  42 , which acts as a retaining means to secure conductor pins  18  within cap  36  in alignment for extending into base  17 . Epoxy  42  is a type of epoxy that is rated for high temperature service. The interior surface of the tapered tubular end  38  has a conical profile, with the rearward end periphery being smaller than the forward end periphery. After cap  36  is fastened to base  17  and epoxy  42  is cured, epoxy  42  will provide a conically shaped layer that is aligned within the conical profile of tapered tubular end  38  and prevents movement of cap  36  and base  17  inward over armor  40  of motor lead  12 . 
         [0019]    As shown in  FIG. 4 , armor  40  has been stripped back from the terminal end of electrical power cable  12 , so that armor  40  has a terminal end of an electrical conductor  22  enclosed within the tapered tubular end  38  of cap  36 . Preferably, each bare electrical conductor  22  is surrounded by one or more layers of conductor insulation  24  to protect and insulate the conductors from one another. Insulation layers  24  will preferably extend within epoxy layer  42  so that the epoxy of layer  42  will bond directly to insulation layers  24 . The insulation layer  24  of each conductor  22  extends sealingly through a rearward rigid insulator member  52 , as shown in  FIG. 4 , and through a deformable elastomeric seal member  54 . In this example, seal member  54  is deformed between rearward insulation member  52  and a rigid forward insulation member  53 . Insulation layer  24  of each conductor  22  extends into forward insulation member  53  but not all the way through forward insulation member  53 . 
         [0020]    At the outer end of base  17 , bare electrical connectors  22  provide a terminal end of power cable  12 . Conductor pins  18  have bores which are separately mounted and then soldered over the terminal ends of bare electrical connectors  22 . Conductor pins  18  are provided for mating with electrical connectors in receptacle  14  ( FIG. 1 ) of the submersible pump motor  9  ( FIG. 1 ). Insulation layer  24  of each conductor  22  extends up to and may abut conductor pin  18 , but does not extend over conductor pin  18 . 
         [0021]    Still referring to  FIG. 4 , electrical insulator members or blocks  52 , 53  may be formed of a hard engineering grade plastic, such as polyetheretherketone (PEEK), and mounted at the forward or lower end of base  17 . Insulator blocks  52 , 53  are fixed within base  17  to prevent axial movement within the housing  30 . Insulator blocks  52 , 53  and seal member  54  are provided with bores  69  therethrough for electrical conductors  22  and for aligning them with the conductor pins  18 . In an example embodiment, forward insulator block  53  has a flat forward end  55  or face that is in a plane substantially perpendicular to conductor pins  18 . An elastomeric sealing boot  66  may extend around a forward lip of base  17  and provide a seal between tubular housing  30  and electrical submersible motor  9 . Boot  66  is shown in  FIG. 4  but not in the other figures. 
         [0022]    Shown set on the forward end  55  of insulator  53  is an example embodiment of the debris seal  15 . In this embodiment the pins  18  are equipped with an optional outer annular sleeve  68  that fit closely around each of conductor pins  18  and protrude a short distance below forward face  55  of insulation block  53 . Sleeve  68 , if used, may be constructed to be part of conductor pins  18  and is formed of an electrically conductive metal. The sleeves  68  are shown inserted though the bores  16  of the debris seal  15 . The inner diameter of each bore  16  is substantially the same as the outer diameter of sleeve  68  for each conductor pin  18 . The expansion slot  19  is shown angularly offset from one of the conductor pins  18  and along a portion of the forward face  55 . 
         [0023]    In addition, an optional O-ring sleeve seal  72  may fit around each conductor pin  18  at the end or rim of each sleeve  68  to seal against any leakage between sleeve  68  and conductor pin  18 . The sealing engagement is formed by the inner diameter and the rearward portion of sleeve seal  72  contacting a shoulder on conductor pin  18  and contacting the rim of sleeve  68 . The outer diameter of sleeve seal  72  does not form a seal and is shown as being only slightly greater in diameter than sleeve  68 . 
         [0024]    Referring to  FIG. 5  illustrates in a side sectional view example embodiments of the pothead connector  15  being electrically coupled with the female receptacle  14 . In this example the pothead connector  15  is being positioned for insertion into the receptacle  14 . The receptacle  14  of  FIG. 5  includes a receptacle block  74  of a rigid insulation material and having a plurality of holes  76  (one shown), one for each conductor pin  18 . A mating electrical conductor sleeve  75  (shown only in  FIG. 5 ) is located within each hole  76  in receptacle block  74  to accept one of the conductor pins  18  as pothead  10  is connected to female receptacle  14 . Each conductor sleeve  75  is connected to one of the wires within motor  9 . Receptacle block  74  has a cylindrical portion with a diameter slightly smaller than the inner diameter of base  17  at its forward end for sliding into lip  17 . Receptacle insulating member  74  has an end face  78  that is flat and parallel with end face  55  of insulating member  53 . 
         [0025]      FIG. 6  illustrates an example embodiment of the pothead connector  10  electrically coupled to the receptacle  14 . In the example of  FIG. 6 , the debris seal  15 , which is between face  55  of insulation member  53  and face  78  of receptacle member  74 , contacts faces  55 ,  78 , thereby creating an effective barrier that prevents debris from getting into the area between conductor pin  18  and pothead  10 . Although the expansion slot  19 , in certain embodiments, allows gaps between the opposing faces  55 ,  78 , the debris seal  15  provides a barrier that fully circumscribes and insulates each pin  18 . As noted above, when thermally expanded, the debris seal  15  will expand into the gaps instead of pushing against the faces  55 ,  78  or base  17 . 
         [0026]    When connected, the optional sleeve seal  72  enters receptacle  76  but is not deformed by receptacle  76  because its outer diameter is smaller than the inner diameter of receptacle  76 . If electrical contact sleeve  75  is sized appropriately, sleeve seal  72  may make contact with the end of electrical contact sleeve  75  to deform sleeve seal  72  against the rim of sleeve  68 . The inner diameter of seal  72  forms a seal around conductor pin  18  and the rim of sleeve  68  to reduce entry of material between sleeve  68  and conductor pin  18 . 
         [0027]    The invention has significant advantages. The end face seals provide an additional barrier to the entry of contaminated material into the area of the electrical contacts. The sleeve seals, if employed, provide still another barrier. It is to be understood that the invention is not limited to the exact details of the construction, operation, exact materials or embodiment shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. For example, the pins could be located in the receptacle and the conductor sleeves could be located in the cable end housing.