Abstract:
Apparatus of components and methods for connecting and sealing a pothead to an electrical cable used in an oil well environment, are provided. Electrical leads are anchored in insulating members retained within the pothead. The leads inserted into passages formed through the insulating members each having an elliptically shaped portion. Channels are formed along the surface of the passages and along the circumference of the elliptically shaped portions. Boot seals are provided in the elliptically shaped portions and circumscribe the electrical leads. A hydrocarbon-based liquid is applied to the boot seals to cause them to swell and occupy the space between the leads and the insulators, including the channels.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Related Applications 
         [0002]    This patent application is a non-provisional of and claims priority to and the benefit of U.S. Provisional Patent Application No. 61/405,875 filed on Oct. 22, 2010, incorporated by reference in its entirety. 
         [0003]    2. Field of the Invention 
         [0004]    This invention relates to methods and apparatus for coupling an electrical cable to an electrical submersible pump electric motor. 
       DESCRIPTION OF THE RELATED ART 
       [0005]    A pothead describes in general a device that couples an electrical cable to an electrical submersible pump (ESP) electrical motor. There are many conventional methods to achieve such coupling. Such conventional methods require a seal to be made between the pothead and electrical cable by according to two primary methodologies. 
         [0006]    In the first methodology, a pothead connection assembly or matching mold is assembled with uncured rubber, which is then baked in the assembly for a length of time so the rubber will cure. In this process, the rubber will fill all of the voids and will set. As there is no free space left within the pothead assembly, during operation at elevated temperatures, there will not be sufficient room for thermal expansion of the rubber. As such, the rubber may exert excessive stress on the cable insulation and pothead internal components, thus limiting the maximum operation temperature to approximately 375° F. depending upon the type of material used. 
         [0007]    In the second methodology, an axial, compressive force is applied to an elastic/pliable material (rubber, plastics, polyimide etc.) by a pair of oppositely positioned insulators, which distributes the force radially, similar in function to a compression fitting. According to this methodology, a seal is preloaded in a fixed volumetric space. Thus, when the temperature around the seal increases, it has no relief from the thermal expansion—again limiting the maximum operation temperature. 
         [0008]    In a third methodology, longitudinally extending springs have been employed to try to limit the amount of excessive compressive force being applied as a result of thermal expansion. According to such methodology, when the compressive force becomes excessive, the longitudinally extending springs are compressed to allow the oppositely positioned insulators to separate. Nevertheless, besides the added complexity, forces may still be applied radially to the cable insulation prior to the rubber expanding longitudinally. 
         [0009]    Further, each of the above methodologies are still affected by swelling of the rubber due to exposure to a dielectric oil, e.g., mineral oil, from the motor and/or hydrocarbons from within the well. 
         [0010]    Recognized, therefore, by the inventor is the need for a pothead connector, boot seal assembly, and boot seal which can provide a seal upon installation and at lower temperatures, that also accounts for both thermal expansion and expansion due to contamination with motor oil and production fluid. 
       SUMMARY OF THE INVENTION 
       [0011]    Various embodiments of the present invention can solve the aforementioned problems. Various embodiments of the present invention advantageously provide a method and pothead assembly for forming a seal around each one of a set of conductors extending down a well bore and into a motor housing of an electrical submersible pump. According to various embodiments of the present invention, pre-cured elastomeric boot seals are utilized to form a seal between the pothead components and the insulation of an electrical cable or other conductor. Dielectric oil can be used as a catalyst with the elastomeric boot seals, to cause the boots to swell into grooves in a portion of the insulator or insulators adjacent the elastomeric boot seals located inside the pothead assembly. The swollen elastomeric boot seals can securely fasten the boots and cable to the pothead assembly, while adding a pressure differential seal. Grooves in the portion of the insulator or insulators adjacent the elastomeric boot seals can allow for thermal expansion of the rubber seal, as well. As such, this configuration can advantageously impede pressure build up from the thermal growth of the rubber and growth due to oil-based contaminants while adding integrity to the locking and sealing mechanism of the boots at operating conditions. Advantageously, various embodiments result in an increase in the maximum continuous downhole operating temperature limitation of approximately 50° F. or more. 
         [0012]    An example of an embodiment of a method of forming a seal around at least one conductor extending through a pothead connector to be connected to a motor of an electrical submersible pump includes the steps of impregnating a boot seal with a catalyst to pre-expand a volumetric size of the boot seal. The boot seal has or contains a bore for receiving a conductor and is configured to sealingly engage inner surface portions thereof with outer surface portions of the conductor. The method also includes inserting the boot seal into at least a portion of a boot seal cavity located within a first insulator before extensive volumetric expansion of the boot seal occurs. The exemplary method also includes inserting the first insulator into a pothead assembly cavity within a housing of the pothead connector, and enclosing the boot seal in the boot seal cavity with a second insulator. The second insulator registers with the first insulator and is also positioned within the pothead assembly cavity within the housing. 
         [0013]    Volumetric expansion initiated upon pre-impregnation with the catalyst continues within the boot seal cavity after insertion therein and further occurs after pre-deployment contamination with motor fluid and upon contact with well fluids and when exposed to environmental temperatures in an operating environment. As such, the boot seal cavity is sized to accommodate a post-expansion volume of the boot seal. Additionally, the step of inserting the boot seal into the boot seal cavity is normally performed prior to the boot seal swelling beyond approximately an internal diameter of either of a plurality of integral annular boot seal retaining and support rings positioned within a medial portion of the boot seal cavity, otherwise the boot seal will likely be damaged during the insertion process and will need to be discarded. 
         [0014]    An example of an embodiment of a pothead connector apparatus for forming a seal around at least one conductor to be connected to a motor of an electrical submersible pump, includes a housing having a pothead assembly cavity and a pothead assembly contained within the housing. The pothead assembly includes a first insulator having first bore extending therethrough having a generally cylindrical shaped portion and a generally conical shaped portion adjacent thereto. The assembly also includes a second insulator having a second bore extending therethrough. The second insulator has a generally cylindrical portion and a generally conical shaped proximal portion adjacent thereto. The conical shaped portion of the second bore registers with the cylindrical shaped portion of the first bore to define a boot seal cavity. A boot seal for receiving a conductor is positioned within the boot seal cavity. The boot seal includes a substantially cylindrical shaped medial outer surface portion, a tapered proximal outer surface portion, a tapered distal outer surface portion, and a throughbore sized to sealingly engage inner surface portions of the boot seal with outer surface portions of the conductor and to sealingly engage with inner surface portions of the first and the second insulators forming the boot seal cavity. 
         [0015]    According to the exemplary configuration, the conical shaped portion of the first insulator includes a conical shaped medial portion contained within the confines of the body of the first insulator. The first insulator similarly has a conical shaped proximal portion adjacent to the conical shaped medial portion and extending through a proximal face of the first insulator. The cylindrical shaped portion of the first insulator includes a plurality of integral annular boot seal retaining and support rings extending into the first bore to provide sufficient support to the boot seal during low-temperature operations in which the boot seal has not expanded into a portion of a volume of the boot seal cavity between adjacent rings of the plurality of annular rings. Correspondingly, the boot seal cavity includes a plurality of annular recesses each surrounding or interleaved with one or more of the plurality of annular boot seal retaining and support rings. According to a preferred configuration, a volume of the boot seal cavity between outer surface portions of the conductor an inner surfaces of the first and second bores defining the boot seal cavity is a fixed volume. As such, the volume of the boot seal cavity exceeds at least approximately 20% of a volume of the boot seal contained within the boot seal cavity to provide for thermal and contaminant-based expansion of the boot seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    So that the manner in which the features and advantages of the invention, as well as others which will become apparent, may be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention&#39;s scope as it may include other effective embodiments as well. 
           [0017]      FIG. 1  is an environmental view of an electrical submersible pump disposed in a well bore according to an embodiment of the present invention; 
           [0018]      FIG. 2  is cross-sectional view of a pothead assembly according to an embodiment of the present invention; 
           [0019]      FIG. 3  is an exploded perspective view of a pothead assembly according to an embodiment of the present invention; 
           [0020]      FIG. 4  is a cross-sectional view of boot seals of a pothead assembly prior to pre-impregnation with oil according to an embodiment of the present invention; and 
           [0021]      FIG. 5  is cross-sectional view of a pothead assembly after pre-impregnation with oil according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. Prime notation, if used, indicates similar elements in alternative embodiments. 
         [0023]    According to various embodiments of the present invention, pre-cured elastomeric boot seals are utilized to form a seal between the pothead components and the insulation of an electrical cable or other conductor. Dielectric oil can be used as a catalyst with the elastomeric boot seals, to cause the boots to swell into grooves in a portion of the insulator or insulators adjacent the elastomeric boot seals located inside the pothead assembly. The swollen elastomeric boot seals can securely fasten the boots and cable to the pothead assembly, while adding a pressure differential seal. Grooves in the portion of the insulator or insulators adjacent the elastomeric boot seals can allow for thermal expansion of the rubber seal, as well. As such, this configuration can advantageously impede pressure build up from the thermal growth of the rubber and growth due to oil-based contaminants while adding integrity to the locking and sealing mechanism of the boots at operating conditions. A more detailed discussion is provided below. 
         [0024]      FIG. 1  is an elevational section view of well bore  10  having electrical submersible pumping system (ESP)  12  disposed therein. ESP  12  includes an electric motor  16 , a seal/equalizer section  15 , an optional separator  17 , and a pump  18 . Pump  18  may comprise a centrifugal pump or a progressing cavity pump, for example. Fluid inlets  19  are shown provided on separator  17  for providing a passage for receiving fluid into ESP  12 . Production tubing  14  is coupled to pump  18  discharge for conveying pressurized production fluid from the ESP  12  to surface. Cable  20  extends downhole, terminating in a connector  21  that electrically couples cable  20  to a motor lead  23 . Motor lead  23 , on its lower terminal end, connects to a pothead connector  22  that electrically connects and secures motor lead  23  to motor housing  24  of electric motor  16 . In another embodiment, cable  20  can extend all the way from the surface to pothead connector  22 , thereby eliminating the need for connector  21 . 
         [0025]      FIG. 2  is a longitudinal cross sectional view depicting an embodiment of pothead connector  22  and  FIG. 3  is an exploded view in accordance with an exemplary embodiment of the pothead connector  22 . In the embodiment shown, pothead connector  22  comprises a housing  31  adapted to connect the pothead connector  22  to the motor housing  24 . As shown, formed into an end of the pothead housing  31  is a cylindrical cavity  33  for containing a compression seal assembly  35  One or more passageways/conduits  37  extend from an opposite end of the pothead housing  31  and into the cavity  33 . The conduits  37  receive a plurality of electrical conductors  39 , one for each phase of the motor  16 . For clarity, it should be noted that  FIGS. 2 and 3  reflect a single electrical conductor  39 . The typical motor  16  for an ESP  12  is a three-phase motor having three conductors  39 . 
         [0026]    As shown in  FIG. 3 , each conductor  39  provides an electrical pathway from surface equipment (not shown) to the electric motor  16  and includes a wire  40  separately insulated by its own insulating layer  41 . A protective barrier of thin-walled tubing  43  surrounds each insulating layer  41  and functions to protect the insulating layer  41  and wire  40  from harsh elements within well bore  10 . In an embodiment of the present invention, the insulating layer  41  and tubing  43  are sized to allow a gap (not shown) between the inner diameter of the tubing  43  in the outer diameter of the insulating layer  41  to form an annulus (not shown) to allow for circulation of dielectric fluids (not shown). The dielectric fluids, when utilized, can provide additional insulation protection to each wire  40  as well as alleviate all air voids. 
         [0027]    As shown in  FIG. 4 , compression seal assembly  35  includes elastomeric boot seals  51  for sealing along an interface between the conductors  39  and the body of the connectors  22 . Each boot seal  51  is typically constructed of an elastomer such as ethylene propylene diene monomer (M-class) rubber but can include other similar materials known to one of ordinary skill in the art, including ALFAS (fluorinated polymer), PTFE, fluoroelastomer, nitrile butadiene (NBR), HNBR. Each boot seal  51  includes a through bore  52  dimensioned to sealingly accommodate the insulating layer  41  therethrough. Optionally, the bore  52  can be sized for sealing engagement with the outer circumference of the wire  40  or tubing  43 . By sealingly engaging the outer surface of one of the conductors  39 , a fluid barrier is provided to prevent the ingress of well fluid into the motor  16  and to prevent loss of motor oil into the well bore  10  during operational employment of the ESP  12 . According to the configuration as shown in  FIG. 4 , the boot seal  51  is in the shape of double sided ferrel or prolate spheroid (football) to enhance bidirectional sealing. 
         [0028]    Referring now to  FIG. 2 , the compression seal assembly  35  also includes a pair of lower and upper insulators  53 ,  55  positioned to compressively house and contain the boot seals  51 . According to the illustrated configuration, lower and upper insulators  53 ,  55  each have generally cylindrical portions and are set generally coaxial within the connector  22 . Bores  57  in the lower insulator  53  register with bores  59  in the upper insulator  55  to define cavities  60 . As shown in  FIGS. 2 and 4 , the boot seals  51  are disposed in the annular space between the conductors  39  and walls of the cavities  60 . As shown in  FIG. 4 , each bore  57  of lower insulator  53  can include a conically shaped bore section  61  extending longitudinally from the “upper” face  63  of the lower insulator  53 , configured to house a portion of one of the boot seals  51 . Each bore  57  further includes a cylindrical shaped bore section  65  for receiving a corresponding female conductor terminal pin  67  positioned to connect the motor  16  to the wires  40 . In the example configuration illustrated in  FIG. 2 , each cylindrical shaped bore section  65  extends through an annular extension  69  housing a substantial portion of the respective female conductor terminal pin  67 . The extension  69  projects from an end of the lower insulator  53  opposite the upper insulator  55  in a direction substantially parallel with an axis of the lower insulator  53 . 
         [0029]    Referring now to  FIG. 4 , each bore  59  of upper insulator  55  can include a combination of a cylindrical shaped bore section  71  extending longitudinally from the “lower” face  73  of the upper insulator  55  and a conically shaped bore section  75  extending longitudinally from the upper confines of the cylindrically shaped bore  71  to house remaining portions of a respective one of the boot seals  51 . Note, although other configurations are within the scope of the present invention, in an example embodiment, about seventy to seventy-five percent of each boot seal  51  is contained within upper insulator  55  with the other twenty-five to thirty percent being contained within lower insulator  53 . Beneficially, the extension of the boot seals  51  across the interface between the upper face  63  of lower insulator  53  and the lower face  73  of upper insulator  55  can help prevent fluid incursions between the faces  63 ,  65 . In the illustrated configuration, the slope of the conically shaped bore sections  61 ,  75  of the lower and upper insulators  53 ,  55 , and thus, the lower and upper portions of the boot seal  51  is between approximately 10°-20°, and more typically approximately 15°. Further, the cylindrical shaped bore section  71  and corresponding section off boot seal  51  is typically between approximately 0.15″-0.23″, and more typically 0.183″ in longitudinal length with sections  61 ,  75  being between approximately 0.180″-0.240″ and more typically 0.220″ in length, respectively. In a typical implementation, there are a limited number of sizes of conductors  39  for any ESP implementation. Accordingly, for such implementation, the inner diameter of bore  52  of each boot seal  51  also comes in a set of generally standard sizes. For standard ESP conductors, the inner diameter is typically approximately 0.320″-0.327″ and more typically 0.322″ for the typical larger conductor; typically approximately 0.298″-0.305″ and more typically 0.300″ for the typical larger conductor; and typically approximately 0.280″-0.287″ and more typically 0.282″ for the typical small conductor. 
         [0030]    According to the illustrated embodiment, upper insulator  55  includes a pair of seals  81 ,  83 , with “upper” seal  81  being primary and “lower” seal  83  being secondary. In an example embodiment, seals  81 ,  83  can be elastomeric O-rings which land within the corresponding annular recesses  85 ,  87  extending along an outer diameter of upper insulator  55  to provide a seal between outer surfaces of upper insulator  55  and inner diameter surfaces of the housing  31  within cavity  33 . An annular retaining nut  91  is threaded on an outer surface, threadingly connecting the nut  91  to corresponding threads  92  formed on an inner circumference of the cavity  33  urges an end of the nut  91  against a ledge shown radially protruding from an outer surface of the lower insulator  53 . Continued threaded engagement between the nut  91  and threads  92  to urge the nut  91  against the ledge in turn urges the lower and upper insulators  53 ,  55  into the cavity  33  to retain the lower and upper insulators  53 ,  55 , and thus, sealingly retain boot seals  51 . An annular shoulder  93  in the housing  31  contacts an upper surface  95  of upper insulator  55  and stops urging of the lower and upper insulators  53 ,  55  into the cavity  33 . 
         [0031]    Beneficially, according to an example embodiment of the present invention, outer diameter surfaces of cylindrically shaped bore  71  include an annular recess formed along its entire periphery. In an optional embodiment, a plurality of annular recesses  101 ,  103 ,  105  are provided in the surface of the cylindrically shaped bore  71 . In the example embodiment of  FIG. 4 , the annular recesses  101 ,  103 ,  105  form a plurality of integral boot seal retaining/support rings  107 ,  109 . In the exemplary configuration, each cavity  60  containing a boot seal  51  has a fixed volumetric space comprising the volume formed by a conically shaped bore sections  61 ,  73 , the cylindrical shaped bore section  71 , and recesses  101 ,  103 ,  105 . This provides cavities  60  with a volume of approximately 0.024354 in. 3  for a standard size conductor  39 , of which approximately 0.003978 in. 3  is provided by recesses  101 ,  103 ,  105 . Also according to the exemplary configuration, the volume of cavities  60  is approximately 20% greater than the volume of the associated portions of the boot seals  51 , e.g., 0.20376 in. 3 , that would fill the cavities  60  prior to pre-impregnation and/or operational impregnation with a dielectric fluid (described below). 
         [0032]    In the exemplary configuration, insulators  53 ,  55  do not include a spring or other means for longitudinally expanding the size of cavity  60  after installation, for example, due to contamination of the boot seals  51  with motor oil or well fluids or due to increased heat associated with the well bore  10  and/or operation of the motor  16 . But rather, through the provision of the plurality of annular recesses  101 ,  103 ,  105  surrounding the cavity  60  in conjunction with a pre-impregnation of each boot seals  51  with the dielectric oil (described below), and in combination with precise sizing of each cavity  60  in relation to the volume of boot seals  51 , various embodiment of the present invention are able to achieve an operational temperature rating at or in excess of 425° F. (e.g., 19° F. to 425° F.). Beneficially, such rating can be accomplished without resorting to the complication of utilization of cavity size adjustment/insulator separation systems, particularly longitudinal based systems that separate upper and lower insulators. 
         [0033]    Further, beneficially, as illustrated, the recesses  101 ,  103 ,  105  and retaining/support rings  107 ,  109  are typically spaced around a middle of each respective boot seal  51 , and positioned to provide sufficient structural support to the medial section of the boot seal  51  when the boot seal  51  does not “fully” fill cavity  60  such as, for example, operation at lower temperatures and/or before extensive well fluid contact. The desired volume of cavity  60  in relation to the volume of e.g. rubber or other sealing material forming the boot seals  51 , are determined based on empirical data describing an amount of swelling to be expected from the boot seals  51  due to dielectric fluid pre-impregnation and motor oil contamination, and an amount of swelling or contraction to be expected from a contaminated boot seal resulting from motor operation and wellbore conditions during operational employment. 
         [0034]    In an example of operation, prior to deployment of the ESP  12  in the well bore  10 , pothead connector  22  is assembled and connected to motor housing  24  of electric motor  16 . In an exemplary assembly process, wires  40  of conductors  39  are extended through the cavity  33  of the housing  31  and through bores  59  of the upper insulator  55 , and wires  40  are connected to female terminal pins  67 . Primary and secondary seal rings  81 ,  83  are positioned in annular recesses  85 ,  87  of upper insulator  55 , and the upper insulator  55  is inserted into cavity  33  of the housing  31  until upper surface  95  of the upper insulator  55  contacts shoulder  93  of the housing  31 . An annular shoulder  93  in the housing  31  adjacent the upper surface  95  of upper insulator  55  functions as a stop for upper insulator  55  when inserted within housing  31 . 
         [0035]    Boot seals  51  are then inserted into cavity  59  of the upper insulator  55 . Prior to insertion, inner and outer surfaces of the boot seals  51  are pre-impregnated with a thin film of a petroleum-based nonconductive dielectric liquid such as polyalphaolefin or similar lubricating and swelling fluids, for example. This can be accomplished with use of an eyedropper (not shown), for example. In an exemplary installation process, two or three drops of oil (i.e., 1.5 ml) are dropped on both the inner and, outer diameter surfaces of the boot seal  51  to initiate pre-operational employment swelling of the boot seals  51 . Note, although polyalphaolefin is preferred, other preferably nonconductive dielectric products such as, for example, perfluorinated polyether can be utilized. Further, in the exemplary configuration, application of the polyalphaolefin is made to the surface only without application of pressure beyond normal surface environmental pressure. Also, any excess polyalphaolefin can be wiped off with an absorbent material. 
         [0036]    After pre-impregnation with polyalphaolefin, boot seals  51  are quickly inserted prior to the boot seals  51  swelling beyond the internal diameter of the integral boot seal retaining/support rings  107 ,  109  to a point where the boot seals  51  cannot be easily inserted without substantial deformation. Where a thin layer of polyalphaolefin is applied to the outer surfaces, insertion will normally be required within a time of no more than approximately 10 minutes. Although the rate of swelling is generally not linear, the amount of swelling expected within approximately 10 minutes is equal to a increase in volume of approximately 0.5% or so with an eventual increase of approximately 1-2%. If swelling in excess of 0.5% or so occurs prior to insertion, the boot seals  51  should be discarded and a replacement set of boot seals  51  are again pre-impregnated with polyalphaolefin and inserted into upper insulator  55 . 
         [0037]    Alignment pin  111  (see, e.g.,  FIG. 2 ) is then inserted into alignment pin bore  113  in the upper insulator  55  and the lower insulator  53  is rotated to align a corresponding alignment pin bore  115  in the lower insulator  53  with the alignment pin  111 . The lower insulator  53  is then inserted into cavity  33 . At this point, boot seals  51  are firmly contained within cavity  60  extending across the lower and upper insulators  53 ,  55 . 
         [0038]    As shown in  FIG. 4 , within each cavity  60 , the outer diameter of a medial portion of the boot seal  51  is in contact with the inner diameter of integral retaining/support rings  107 ,  109 . As will be described in more detail below, as the boot seal  51  swells, it begins to fill the portion of the cavity  60  formed by recesses  101 ,  103 ,  105 . Further depicted in the embodiment of  FIG. 4 , the conical portion  61  of lower insulator  53  and conical portion  75  of the upper insulator  55  contain the tapered portions of boot seals  51  to further enhance sealing of the boot seals  51  around the outer diameter of the insulation  41  or tubing  43  of conductors  39  as the boot seal  51  swells. 
         [0039]    It should be noted that although swelling due to polyalphaolefin is not instantaneous, if there is a delay in inserting the pre-impregnated boot seals  51 , e.g., of more than approximately 10 minutes, the boot seals  51  will likely need to be discarded as they may have swelled beyond their capacity to be properly inserted without potential damage. 
         [0040]    In an example of assembly, the boot seals  51  are inserted and the lower insulator  53  is positioned in contact with upper insulator  55 . The retaining nut  91  is threadingly connected to corresponding annular threads  92  within the cavity  33  of the housing  31  to retain the lower and upper insulators  53 ,  55 , thereby encapsulating the boot seals  51  in the cavities  57 ,  59  of the insulators  53 ,  55 . As illustrated in the example embodiment of  FIG. 5 , the encapsulated boot seals  51  continue to swell and expand into cavity  60  as a result of polyalphaolefin and motor oil impregnation and as a result of thermal expansion. 
         [0041]    Referring again to  FIG. 3 , when the operator is ready to connect the pothead assembly  22  to the motor housing  24  ( FIG. 1 ), a lead washer  121  is inserted around a retaining nut extension  123 , a retaining nut boot seal  125  is inserted over the retaining nut extension  123 , and the housing  31  is connected to the motor housing  24  using, for example, a pair of bolts (not shown) extended through a corresponding pair of bolt holes  127 . Upon connection to the motor housing  24 , boot seals  51  are then exposed to the oil (e.g., polyalphaolefin) from the motor  16 . This will induce further pre-deployment swelling, typically in a range of approximately 10-20% within approximately 24 hours of connection. 
         [0042]    After the additional pre-swelling due to the motor oil is completed, the ESP  12  is then lowered down the wellbore  10  as in the example embodiment in  FIG. 1 , where the upper end of the boot seals  51  are exposed to well fluids including hydrocarbons, water, brine, and well treatment fluids and aromatics such as, for example, Xylene, Toluene, and Benzene. Once exposed to well fluids and typical temperatures of between 200-350° F., swelling of the boot seals  51  can be expected to be within the 30-40% range, which as shown in  FIG. 5 , is readily accommodated by cavity  60 . Note, exposure to well fluids, particularly the aromatic fluids, can result in a swelling of between approximately 50-60%. This level of swelling, however, generally only occurs on a very small portion of the upper end of boot seals  51  adjacent a conically shaped well fluid inlet portion  113  of bore  59 , that is in actual physical contact with the well fluids, and thus, does not result in excessive compression being applied to conductor  39 . 
         [0043]    Various embodiments of the present invention have several advantages. For example, various embodiments of the present invention account for boot seal contamination with oil which results in the boot seal  51  having a larger size than that of its manufactured size, by determining the expected size of the contaminated boot seal  51  and adjusting the size of the cavity  60  containing the boot seal  51  to account for such size increase. Further, various embodiments of the present invention ensure a proper pre-deployment seal between the pothead assembly  22  and ESP motor conductors  39  by pre-impregnating the boot seals  51  with oil. Further, various embodiments of the present invention extend the maximum operating temperature of the pothead assembly  22  by further sizing the cavity  60  to account for both motor oil contamination in conjunction with thermal expansion, while limiting the size of the cavity  60  and/or adjusting its shape to prevent leakage during cold operations. 
         [0044]    This patent application is a non-provisional of and claims priority to and the benefit of U.S. Provisional Patent Application No. 61/405,875 filed on Oct. 22, 2010, incorporated by reference in its entirety. 
         [0045]    In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification.