Abstract:
A high temperature connector for use in connecting a power cable to an electric motor includes an outer housing, an inner housing inside the outer housing and a cable conductor disposed through the inner housing. To maintain a seal around the cable conductor during thermal expansion and contraction, the connector includes at least one spring-energized seal disposed around the cable conductor. The spring-energized seal permits the expansion and contraction of the cable conductor without deforming the cable conductor or the inner housing.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of submersible pumping systems, and more particularly, but not by way of limitation, to a connector for use in connecting a power cable to a component in a downhole pumping system. 
       BACKGROUND 
       [0002]    Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, the submersible pumping system includes a number of components, including one or more fluid filled electric motors coupled to one or more high performance pumps. Each of the components and sub-components in a submersible pumping system must be engineered to withstand an inhospitable downhole environment, which may include wide ranges of temperature, pressure and corrosive well fluids. 
         [0003]    Typically a power cable and motor lead cable supply power to downhole components through a pothead connection. High temperature electrical pothead designs often use a compression seal, like an o-ring, to seal the cable insulation to the inner block of the pothead&#39;s housing. As the cable insulation expands under high downhole temperatures, such as temperatures approaching or exceeding 250° C., the insulation presses against the compression seal, and the compression seal expands until it is compressed into the mounting grooves of the pothead&#39;s housing. This expansion may also cause the compression seal to press into and deform the cable insulation. When the downhole temperature cycles back down, the insulation contracts back down toward the copper core of the cable. If the insulation was deformed by the expansion of the compression seal, the compression seal may not properly seal onto the insulation. Without a proper seal, well fluid may leak through the pothead and into the motor or other downhole component. Well fluid leaking into the motor can cause decreased motor performance and eventual motor failure. 
         [0004]    Accordingly, there is the need for an improved sealing device that will allow expansion to occur at high temperatures without deformation of the cable insulation and incorporate the sealing mechanism into a single, simple, compact design. It is to these and other deficiencies in the prior art that the present invention is directed. 
       SUMMARY OF THE INVENTION 
       [0005]    In preferred embodiments, the present invention includes a high temperature connector for use in connecting a power cable to an electric motor. The connector includes an outer housing, an inner housing inside the outer housing and at least one cable conductor disposed through the inner housing. To maintain a seal around the cable conductor during thermal expansion and contraction, the connector includes at least one spring-energized seal disposed around the cable conductor. The spring-energized seal permits the expansion and contraction of the cable conductor without deforming the cable conductor or the sealing mechanism against the inner housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an elevational view of a submersible pumping system constructed in accordance with a presently preferred embodiment. 
           [0007]      FIG. 2  is a perspective view of the connector for connecting the motor lead extension to the motor of the pumping system. 
           [0008]      FIG. 3  is a cross sectional view of the connector from  FIG. 2 . 
           [0009]      FIG. 4  is a front view of the spring-energized seal from the connector of  FIG. 2 . 
           [0010]      FIG. 5  is a perspective view of the spring-energized seal from  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]    In accordance with a preferred embodiment of the present invention,  FIG. 1  shows an elevational view of a pumping system  100 . The pumping system  100  is attached to production tubing  102  and is disposed in a wellbore  104 . The pumping system  100  includes a variety of downhole components, e.g. an electric motor  106 , a seal section  108 , a pump  110  and a power cable  112 . 
         [0012]    The pumping system  100  further includes a motor lead extension (MLE)  114  and pothead connector  116 . The MLE  114  is preferably configured to have a lower profile than the power cable  112  because it resides within the smaller annular space between the pumping system  100  and the wellbore  104 . The MLE  114  may also include additional armor and shielding to guard against damage from contact with the pumping system  100 . The power cable  112  extends downhole and is connected to the MLE  114  on its lower end. The MLE  114 , in turn, is connected to the pothead connector  116 , which secures the MLE  114  to the motor  106 . Alternatively, the power cable  112  may extend from the surface directly to the connector  116 . 
         [0013]    Although the power cable  112  and MLE  114  are depicted in  FIG. 1  as being connected to the motor  106 , it will be understood that the power cable  112  or MLE  114  may be connected to other components of the pumping system  100  through the connector  116 . It will also be understood that, although each of the components of the pumping system are primarily disclosed in a submersible application, some or all of these components can also be used in surface pumping operations. It will further understood that although the components of the pumping system  100  are depicted in a vertical orientation, it will be appreciated that the pumping system  100  can also be disposed in a horizontal or deviated wellbore  104 . 
         [0014]    Turning now to  FIGS. 2 and 3 , depicted therein are perspective and cross sectional views, respectively, of the connector  116 . The connector  116  includes an outer housing  118 , an inner housing  120 , and a compression nut  122 . The connector  116  includes flanges that are configured for connection to the motor  106  with bolts or other fasteners (not shown). The outer housing  118  is preferably manufactured from a corrosion-resistant metal, ceramic or heat-resistant plastic. The inner housing  120  is manufactured from a metallic material of suitable thermal expansion property or an electrically insulating, heat-resistant polymer such as polyether ether ketone (PEEK), or ceramic. The compression nut  122  secures the inner housing  120  within the outer housing  118 . 
         [0015]    The connector  116  further includes one or more cable conductors  124  that pass through the compression nut  122  and inner housing  120  of the connector  116 . In a particularly preferred embodiment, the connector  116  includes three cable conductors  124  that each correspond to a different phase of electrical power provided to the three-phase electric motor  106 . 
         [0016]    Each of the cable conductors  124  includes a core  126 , an insulating layer  128  and a sheath  130 . The core  126  typically consists of copper or another conductive material to provide an electrical connection to the motor  106  or other component of the pumping system  100 . The insulating layer  128  is made out of an insulating material, such as Ethylene Propylene Diene monomer (EPDM), polyether ether ketone (PEEK) or epitaxial co-crystallized perfluoropolymer. The sheath  130  acts as a protective barrier to protect the cable conductors  124  from hazardous, high temperature well environments. Each of the cable conductors  124  is configured for connection with the MLE  114  and internal wiring within the motor  106 . 
         [0017]    The connector  116  further includes one or more spring-energized seals  132  and may also include one or more o-rings  134 . The number of spring—energized seals and o-rings will vary depending on thermal expansion difference between inner housing  120  and outer housing  118 . As depicted in  FIGS. 4 and 5 , the spring-energized seal  132  includes two or more lip seal flaps  136  and a spring  138  running between the two or more lip seal flaps  136 . In a preferred embodiment, the spring  138  is a coiled or spiraled metal wire or strip. The resiliency of spring  138  allows the seal  132  to repeatedly expand and contract without permanent deformation. 
         [0018]    During the operation of the motor  106 , the connector  116  is exposed to cycles of increasing and decreasing temperatures. During these thermal cycles, the insulating layer  128  of the cable conductors  124  undergoes alternating periods of expansion and contraction around the core  126  of the cable conductors  124 . As the insulating layer  128  expands, it presses outward on the spring-energized seal  132 . The spring-energized seal  132  accommodates the expansion and contraction of the insulating layer  128  of the conductors  124  to maintain a fluid seal through the connector  116 . 
         [0019]    More particularly, during expansion of the insulating layer  128 , the spring  138  in the spring-energized seal  132  is radially compressed, thereby allowing the insulating layer  128  of the cable conductors  124  to expand toward the inner housing  120  of the connector  116  without deformation of the insulating layer  128 . As the temperature recedes and the insulating layer  128  contracts, the spring  138  expands and presses the lip seal flaps  136  back onto the insulating layer  128 . Thus, the spring-energized seal  132  maintains a seal around the cable conductors  124  which prevents well fluid from passing through the inner housing  120  of the connector  116  and into the motor  106 . 
         [0020]    It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.