Patent Document

FIELD OF THE INVENTION 
   The present invention relates generally to a high temperature pothead used to provide power to a submersible component such as a submersible motor. More particularly, the present invention provides a high temperature pothead that does not require elastomeric sealing elements. 
   BACKGROUND OF THE INVENTION 
   In a variety of applications, it is necessary to form liquid-tight seals between an electrical power cable and a component. For example, in subsurface production of liquids, such as oil, it may be necessary to provide electrical power to an electric submersible pumping system. Typically, a power cable is run downhole and connected to a submersible electric motor. The electric motor is powered to turn a centrifugal pump that intakes the production fluid and raise it or move it to a desired location, such as the surface of the earth. 
   In such applications, the electric submersible pumping system often is utilized within a wellbore at a location deep beneath the surface of the earth. In that type of environment, components are subjected to extreme pressures, extreme temperatures, and often corrosive environments. Thus, it can be difficult to form a lasting, fluid-tight seal between the power cable and the submersible component, e.g. submersible motor. 
   In conventional connectors, e.g. potheads, the conductors of the power cable are disposed through a connector housing and through the outer housing of the submersible component for appropriate connection. Within the connector housing, a plurality of blocks are used to support the individual conductors. Typically, an elastomeric block or blocks is disposed between a pair of relatively hard blocks. The hard blocks are utilized to squeeze the elastomeric block until it forms a seal between the individual conductors and the interior surface of the connector housing. Additional elastomeric seals are used to prevent fluid flow between the connector and the submersible component housing. 
   The elastomers used to form the seals are subject to degradation from thermal exposure, compression set due to thermal cycling (i.e. system starts and stops), and H 2 S gas transmission. When providing power in an environment having very high operating temperatures, the seals expand and exert great pressure on the conductor insulation which can result in the insulation tearing and opening a path to ground. 
   There exists, therefore, a need for a high temperature pothead that does not utilize elastomeric seals. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front elevational view of a typical submersible pumping system disposed within a wellbore and powered via a multiconductor power cable. 
       FIG. 2  is a side view showing in partial cross-section an embodiment of the high temperature connector of the present invention providing a connection between a power cable and a submersible component, e.g., submersible motor. 
       FIG. 3  is an end view of an embodiment of the high temperature connector of the present invention. 
       FIG. 4  provides a side cross-sectional view of an embodiment of the high temperature connector of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring generally to  FIG. 1 , an exemplary, high-pressure, high temperature environment is illustrated. The high temperatures and pressures in wellbore environments often can be above 150 degrees Fahrenheit and 3000 pounds per square inch (psi), respectively, and in many applications, the wellbore environment can exceed high temperatures and high pressures of 300 degrees Fahrenheit and 10,000 psi, respectively. In this particular application, a power cable is coupled to a submersible pumping system in a downhole, wellbore environment by a connector, e.g. pothead. The pumping system may be an electric submersible pumping system  10 . Typically, the system  10  includes at least a submersible pump  12 , such as a centrifugal pump, a submersible motor  14  and a motor protector  16 . 
   In the illustrated example, the pumping system  10  is designed for deployment in a well  18  within a geological formation  20  containing desirable production fluids, such as petroleum. In a typical application, a wellbore  22  is drilled and lined with a wellbore casing  24 . The wellbore casing  24  may include a plurality of openings  26  through which production fluids may flow into the wellbore  22 . 
   The pumping system  10  is deployed in the wellbore  22  by a deployment system  28  that may have a variety of forms and configurations. For example, the deployment system  28  may comprise tubing  30  connected to the pump  12  by a connector  32 . Power is provided to the submersible motor  14  via a power cable  34  coupled to a submersible component, e.g., the motor  14 , by a power cable connector or a pothead  35 . The motor  14 , in turn, powers the centrifugal pump  12  which draws production fluid in through a pump intake  36  and pumps the production fluid to the surface via the tubing  30 . 
   It should be noted that the illustrated submersible pumping system  10  is merely an exemplary system. Other components can be added to the system, and other deployment systems may be implemented. Additionally, the production fluids may be pumped to the surface through the tubing  30  or through the annulus formed between the deployment system  28  and the wellbore casing  24 . Also, the power cable  34  may be coupled to other submersible components. 
   The present invention provides a high temperature connector  35  particularly advantageous in high temperature environments. The high temperature connector  35  of the present invention does not use elastomeric seals and thus avoids any detrimental effects caused by exposing the elastomers to very high operating temperatures. 
   Referring back to  FIGS. 2 and 3 , the pothead seal flange  42  fits into the motor-head pothole after the brush-wires are crimped and taped on. The pothead seal flange  42  has a pair of axial holes  62  formed therethrough. The axial holes  62  are designed to receive conventional fasteners, such as bolts, that are threadingly engaged with the housing of the submersible component  14 . The pothole seal may be made with a Metal Spring Energized (MSE) seal  64  of the type, for example, that utilizes a corrosion-resistant metal spring placed under compression between a portion of seal flange  42  and the housing of submersible component  14 . 
   The power cable  35  includes one or more conductors  38 . A lead jacket  40  is extruded onto the conductors  38  of the power cable  35  to form a protective barrier. In the illustrated embodiment, the power cable  34  has three conductors  38  for carrying three-phase power to a submersible component, such as the motor. Of course, a variety of other power cables may be utilized for providing electrical power to a variety of components. 
   The high temperature connector  35  of the present invention comprises a pothead seal flange  42  and one or more conductor tubes  44 . The number of conductor tubes  44  typically corresponds with the number of conductors  38  existing within the power cable  34 . The conductor tubes  44  are welded into the pothead seal flange  42  to form a path for each conductor  38  to feed through. In an embodiment of the present invention, the pothead seal flange  42  and the conductor tubes  44  are formed from Monel  400 . 
   As best described with reference to  FIG. 4 , prior to inserting the conductors  38  into the conductor tubes  44 , the lead jacket  40  on each cable conductor  38  is removed back to an appropriate location, taped off with high modulus PTFE tape  46 , and soldered to the inside of the conductor tubes  44  with solder paste  48 . The conductors  38  are inserted into the conductor tubes  44  such that they protrude through the pothead seal flange  42  and are terminated via a plurality of terminals  50 . The terminals  50  are designed for plugging engagement with corresponding receptacles  52  of the submersible component as shown in dashed lines in FIG.  4 . 
   Once the conductors  38  have been soldered to the inside of the conductor tubes  44 , oversized, lead splice tubes  54  are slit and placed around and over the junctions between the conductor tubes  44  and the lead jackets  40 . The open edges of the lead splice tubes  54  are then pinched upward and together to bring the lead splice tubes  54  into engagement with the conductors  38 . The excess of the lead splice tubes  54  are trimmed off and the tubes  54  are soldered in place, forming metal-metal seals  56  between the conductor tubes  44  and the lead jackets  40 . 
   The lead splice tubes  54  are soldered in place at both the junctions  58  of the lead splice tubes  54  and the lead jackets  40  and at the junctions  60  of the lead splice tubes  54  and the conductor tubes  44 . 
   The lead/lead soldering at the junctions  58  between the lead splice tubes  54  and the lead jackets  40  is actually a welding process. The material on either side of the joint melts and fuses together. Thus, there is no need to rely on a wetted solder joint. 
   The lead/conductor tube soldering at the junctions  60  between the lead splice tubes  54  and the conductor tubes  44  is a high temperature solder joint. In embodiments of the high temperature connector  35  using Monel as the conductor tubes  44 , the solder joint can be made with 95/5 rod solder, 88/10/2 paste solder, or 95/5 paste solder, for example. 
   It should be understood that the conductor seal  56  of the high temperature connector  35  of the present invention can be moved farther from the back of the pothead seal flange  42  by increasing the length of the conductor tubes  44 . As the distance from the pothead seal flange  42  increases, to a point, the operating temperature decreases. Thus, locating the conductor seal  56  distant from the pothead seal flange  42  will act to lower the overall operating temperature to which the conductor seal  56  is exposed. 
   Referring back to  FIGS. 2 and 3 , the pothead seal flange  42  fits into the motor-head pothole after the brush-wires are crimped and taped on. The pothead seal flange  42  has a pair of axial holes  62  formed therethrough. The axial holes  62  are designed to receive conventional fasteners, such as bolts, that are threadingly engaged with the housing of the submersible component  14 . The pothole seal is made with a Metal Spring Energized (MSE) seal  64 . 
   It should be understood that embodiments of the high temperature connector  35  of the present invention can be used to advantage for a single conductor connection by varying the geometry of the pothead seal flange  42  and the motor-head. The present invention can also work as a plug-in for either a single conductor or regular, three conductor pothead. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such are intended to be included within the scope of the following non-limiting claims.

Technology Category: 2