Abstract:
An electrical submersible pumping system (ESP) for pumping fluids from a wellbore is made of segments, which include a motor, a seal section, a pump, and a shaft assembly connected to an output of the motor drives the pump. The motor, seal section, and pump are elongate members and coupled end to end to one another by housing connectors and shaft connectors. At least one of the housing connectors and shaft connectors have portions that are pivotable with other portions, so that adjacent segments of the ESP system can pivot with respect to one another. The housing connector can be a ball and socket assembly, where the ball fits within a spherically shaped chamber in the socket assembly. Opposing ends of the housing connector can mount to respective segments by threads or bolt flanges. The pivotal shaft connector may be a universal joint.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to provisional application 61/739561, filed Dec. 19, 2012. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates in general to electrical submersible well pump assemblies, and in particular o a well pump assembly having segments that are coupled to each other by a connector that allows pivoting between adjacent segments. 
     BACKGROUND 
     In oil wells and other similar applications in which the production of fluids is desired, a variety of fluid lifting systems have been used to pump the fluids to surface holding and processing facilities. It is common to employ various types of downhole pumping systems to pump the subterranean formation fluids to surface collection equipment for transport to processing locations. One such conventional pumping system is a submersible pumping assembly which is supported and immersed in the fluids in the wellbore. The submersible pumping assembly includes a pump and a motor to drive the pump to pressurize and pass the fluid through production tubing to a surface location. A typical electrical submersible pump assembly (“ESP”) includes a submersible pump, an electric motor and a seal section interdisposed between the pump and the motor. Sometimes the ESP assembly can include a separator to isolate fluids of different phases from one another. Depending on the particular application, the pump is usually a centrifugal pump or a progressing cavity pump. 
     Not all wells from which fluid is pumped with an ESP assembly are vertical. Some wells are deviated, i.e. not vertical, and some have are highly deviated and include horizontal portions. Because the upper portions of substantially all wells are vertical, wells having a horizontal portion bend when transitioning from vertical to horizontal. The bend in the well can introduce difficulties when deploying the ESP assembly, as the segments of the ESP assemblies form an elongate rigid member; which must flex to the same radius as the bend when being inserted downhole. 
     SUMMARY 
     The electrical submersible pump assembly disclosed herein has segments attached end to end and including a motor, a pump, and a seal section between the pump and the motor. Each of the segments has a housing and a rotatable shaft. At least one pivotal housing connector is attached between the housings of adjacent segments, allowing pivoting of the housings relative to each other. At least one pivotal shaft connector is attached between the shafts of adjacent segments. The shaft connector allows pivoting of the shafts of adjacent segments. 
     Preferably, the pivotal shaft connector is a universal joint mounted within the pivotal housing connector. The pivotal housing connector prevents axial rotation of one of the housings relative to the other of the housings. In the embodiment shown, the pivotal housing connector has two flanges facing in opposite directions. The flanges are bolted or secured by threads to the housings. 
     The pivotal housing connector may comprises a ball and socket arrangement. A key and slot located between the socket and the ball element prevent axial rotation of one of the housings relative to the other of the housings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some of the features and benefits of the present disclosure having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a side partial sectional view of an example of an electrical submersible pumping (ESP) system disposed in a deviated wellbore in accordance with the present disclosure. 
         FIG. 2  is a side sectional view of an example of a connector for pivotingly connecting adjacent segments of the ESP system of  FIG. 1  and in accordance with the present disclosure. 
     
    
    
     While the subject device and method will be described in connection with the preferred embodiments but not limited thereto. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the present disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the disclosure are shown. This disclosure 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 through and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout. 
       FIG. 1  is a side partial sectional view of an example of an electrical submersible pump assembly  10  deployed within a wellbore  12  that has a vertical portion  14 A and a deviated portion  14 B, both normally being cased. Deviated portion  14 B may be horizontal. The embodiment of the pump assembly  10  illustrated includes a motor  16  on its lower end whose upper end is coupled with a seal section  18 . Seal section  18  has means, such as a bladder, for reducing a pressure differential between lubricant in the motor and hydrostatic well fluid pressure. An optional separator  20  is shown attached on an upper end of seal section  18  and distal from motor  16 . A pump  22  is shown mounted onto an end of separator  20  distal from seal section  18 . Production tubing  24  is shown connected to an end of pump  22  opposite separator  20  and extending upward through the wellbore  12 . An upper end of the production tubing  24  terminates within a wellhead assembly  26  shown mounted on surface above an opening to the wellbore  12 . An inlet  27  is shown formed through a side wall of separator  20  which allows for fluid within wellbore  12  to enter the pump assembly  10 . Inside the separator  20 , different phases within the fluid (not shown) are isolated from one another. Liquid extracted from the wellbore fluid is directed to the pump  22 , where it is pressurized and delivered, to production tubing  24  for delivery to the wellhead assembly  26 . The vapor fraction of the wellbore fluid can be directed up the wellbore  12  to the wellhead assembly  26 , and outside of the pump assembly  10 . Embodiments of a pump assembly  10  not having a separator  20  exist, in these embodiments inlet  27  may be provided on the pump  22 . 
     The segments of the pump assembly  10 , e.g., motor  16 , seal section  18 , separator  20 , and pump  22 , are connected to one another by connectors  28  shown set between each adjacent segment. Each connector  28  is pivotable, so that the segments that it joins can pivot relative to each other When passing through the transition between well vertical portion  14 A and horizontal portion  14 B. That is, each segment can pivot into an orientation with its axis oblique to an axis of an adjacent segment. Thus when the pump assembly  10  encounters a curved transition in the wellbore  12 , the pivoting connectors  28  introduces pliability to the pump assembly  10  so it can flex to a curved shape of the wellbore  12  and be inserted past the bend in the wellbore  12 . 
     Alternately, some of the connectors between segments could be rigid, non pivoting types, and others could be pivotal connectors  28 . As an example, some of the segments of pump assembly  10  are much longer than others, such as a length of motor  16  versus seal section  18 . An operator may choose to employ a rigid connection between motor  16  and seal section  18 , as an example. Also, motor  16  could be tandem motors coupled together and pump  22  could comprise, tandem pumps  22 . The tandem components could be coupled together by conventional rigid connectors or by pivotal connectors  28 . 
     Referring now to  FIG. 2 , an example of a connector  28  is shown in a side sectional view.  FIG. 2  illustrates the connector  28  connecting between seal section  18  and motor  16 , but the description applies to the other modules of pump assembly  28 , as well. Further, even though connector  28  is shown connecting motor  16  with seal section  18 , a conventional non pivotal connector could be employed between motor  16  and seal section  18 , and pivotal connector  28  employed elsewhere in pump assembly  10 . 
     Connector  28  includes a housing connector or socket assembly  30  having a passage or bore  32  extending along an axis A x  of the socket assembly  30 . A curved cavity  34 , which may be spherical, is formed within the socket assembly  30  and circumscribes a mid-portion of bore  32 ; socket cavity  34  movably receives therein a male portion  36  of socket assembly  30 . The male portion  36  of socket assembly  30  has a curved member shown to be spherically-shaped ball  38  shown set within cavity  34 . 
     Socket assembly  30  has an annular collar  33  with an external flange  35  on an end opposite cavity  34 . External flange  35  threadingly secures to a housing  39  of seal section  18 , such as by bolts  37 . Alternately, flange  35  could be rigidly connected in other manners, such as by external threads on flange  35  that engage internal threads in seal section housing  39 . 
     Male portion  36  has an annular collar  40  extending downward from ball  38  to outside of the socket assembly  30 . Collar  40  has a flange  41  that threadingly couples to a housing  43  of motor  16 , such as by bolts  45 . Alternately, the outer diameter of flange  41  could have external threads that engage internal threads in housing  43 . Connector  28  could be inverted with flange connecting to seal section  18  and flange  35  rigidly connecting to motor  16 . 
     The socket assembly  30  is shown having a male end  42  that threadingly couples to a female end  44 , where female end  44  circumscribes a portion of the ball  38  adjacent collar  40 , and also circumscribes a portion of collar  40 . Male end  42  circumscribes a portion of ball  38  distal from collar  40 . Included with male end  42  is an annular external pin portion  46  that extends axially towards the collar  40  and has threads provided along at least some of its outer surface. Pin portion  46  inserts into a box  48  that is coaxially formed within female end  44  and configured to receive pin portion  46  therein. Threads provided along an inner surface of box  48  mate with threads on the outer portion of pin  46  to form a threaded connection that extends coaxially around axis A x . In one example of assembly of the connector  28 , while male and female ends  42 ,  44  are initially disconnected from one another, ball portion  36  inserts into spherical cavity  34  and is oriented so that collar  40  projects through an opening formed in the side of female end  44  formed by bore  32 . With ball  38  positioned inside cavity  34 , the pin  46  on male end  42  can be inserted within box  48  on female end  44 , and a threaded connection formed to couple together male and female ends  42 ,  44 . 
     A slot  50  and key  52  are located between ball  38  and spherical cavity  34  to restrict pivotal movement of ball  38  in cavity  34  to a single plane.  FIG. 2  shows key  52  mounted to a circumferential portion of cavity  34  and slot  50  on ball  38 , but that arrangement could be reversed. Slot  50  is elongated more than a height of key  52  to enable ball  38  to pivot at oblique angle relative to axis Ax. Slot  50  and key  52  prevent rotation of ball  38  in socket  34  about axis Ax, thus connectors  28  prevent axial rotation of the housings of the various segments of ESP  10  relative to each other. Arrangements other than slot  50  and key  52  are feasible to prevent rotation of ball  38  in cavity  34  about axis Ax are feasible. 
     Still referring to  FIG. 2 , a passage or bore  54  is shown formed axially through the ball portion  36  and generally coaxial with axis A x . Bore  54  is in fluid communication with passage  32 , and both are in fluid communication with interior portions of seal section  18  and motor  16 . Preferably bores  32  and  54  are sealed from exterior well fluid, and this may be done with seals  53  that seal between socket cavity  34  and ball  38 . In this example, one seal  53  is mounted to male end  42  within cavity  34  and another to female end  44  within cavity  34 , but other arrangements are feasible. 
     A pivotal shaft connector or coupling assembly  56 , shown set within bore  54 , rotationally couples motor shaft  58  to seal section shaft  60 . Shaft coupling assembly  56  transmits torque between shafts  58 ,  60  and allows shafts  58 ,  50  to tilt oblique to axis Ax. Shaft coupling assembly  56  is preferably a universal joint. In the example of  FIG. 2 , shaft coupling assembly  56  has a first coupling member  62  and a second coupling member  66 . First coupling member  62  is shown in cross section, and second coupling member  66  is shown in a side view. Each coupling member  62 ,  66  has an internal splined receptacle  63 . Each shaft  58 ,  60  has a splined end  64  that inserts into and meshes with one of the splined receptacles  63 . 
     Each shaft coupling member  62 ,  66  has circumferentially spaced apart lugs  70  on the end opposite its splined receptacle  63 . Lugs  70  extend axially and are spaced apart 180 degrees. Pins  72  extend between lugs  70  and a central gimbal  74 , which may be a cylindrical disk. Lugs  70  and pins  72  on one of the coupling members  62 ,  66  are spaced 90 degrees from those on the other coupling member  62 ,  66 . Coupling members  62 ,  66  allow tilting of shafts  58 ,  60  relative to each other, but still transmit rotation. Shaft coupling assembly  56  is centrally located within ball bore  54  and sealed from well fluids by seals  53 . Other types of shaft coupling assemblies  56  rather than the universal joint shown are feasible. 
     During operation, the operator secures the various segments, such as motor  16 , seal section  18 , pump  20 , and optionally gas separator  22  with connectors, at least one of which will be a pivotal connector  28 . While lowering the pump assembly  10  in cased well  12 , the segments can pivot relative to each other when reaching the transition between the vertical portion  14 A and the inclined portion  14 B of well  12 . While pivoting, ball  38  will pivot relative to cavity  34  oblique to axis Ax, rotating about a center point of ball  38  along the portion of axis Ax within ball bore  54 . Similarly, shaft coupling  62  will pivot relative to shaft coupling  66  about a center point of gimbal  74  perpendicular to the portion of axis Ax passing through shaft coupling  56 . The center or pivot points of socket assembly  30  and shaft connector  56  may coincide with each other. 
     When reaching the desired depth, typically pump assembly  10  will be within a straight portion of the inclined section  14 B of well  12 . Motor  16 , seal section  18 , separator  20  and pump  22  will again be co-axial with each other. The operator supplies electrical power to motor  16 , which causes shaft  58  to rotate. Shaft coupling  56  transmits the rotation to seal section shaft  60 . The various couplings between the shafts of the segments of pump assembly  10  cause pump  22  to operate and pump fluid from the well. Housings  39  and  43  of seal section  18  and motor  16  do not rotate about their axes. Slot and key  50 ,  52  prevent housings  39  and  43  front axial rotation relative to each other. Pump assembly  10  can also be operated with segments within a curved transition of well  12 . Shaft coupling  56  will transmit rotation of shaft  58  to shaft  60  even when the axis of shaft  58  is inclined relative to the axis of shaft  60 . 
     It is understood that variations may be made in the above without departing from the scope of the disclosure. While specific embodiments have been shown and described, modifications can be made by one skilled in the art without departing from the spirit or teaching of this disclosure. The embodiments as described are exemplary only and are not limiting. Many variations and modifications are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.