Abstract:
An electrical submersible pumping (ESP) system for use in a wellbore that can be assembled in the wellbore. Upper and lower pump tandems are fitted with connectors that align the tandems when coupled in the wellbore. The connectors on the lower tandems have bores with enlarged openings on upward facing surfaces. Downward pointing pins are on lower facing surfaces of the connectors on the upper tandems. The cross sectional area of each bore decreases with distance away from the openings, so that as the pins insert into the bores the pins move along a helical path that in turn rotates the upper tandem into a designated azimuth and into alignment with the lower tandem. Properly aligning the upper and lower tandems couples respective drive and driven shafts in the tandems as the upper tandem lands on the lower tandem.

Description:
RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/424,937, filed Dec. 20, 2010, the full disclosure of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of Invention 
     This invention relates in general to oil and gas production and in particular to a device for coupling together segments of electrical submersible pumps. 
     2. Description of Prior Art 
     An electrical submersible pumping (ESP) system for a hydrocarbon producing well is normally installed within casing on a string of tubing or deployed within the tubing itself. Usually the tubing is made up of sections of pipe screwed together. Coiled tubing deployed from a reel may also be used. The motor is often powered with a power cable that is strapped alongside the tubing. The pump is typically located above the motor, is connected to the lower end of the tubing, and pumps fluid through the tubing to the surface. One type of a pump is a centrifugal pump using a plurality of stages, each stage having an impeller and a diffuser. Another type of pump, for lesser volumes, is a progressing cavity pump. 
     To contain pressure in the wellbore, ESP systems are typically deployed in a wellbore with the use of a wellhead lubricator. Where the lubricator is generally suspended above an opening to the well using an on-site crane. Safety and environmental concerns limit the maximum length of the lubricator, thereby limiting the size and length of ESPs. Some applications though may require an ESP system to have a length in excess of the maximum length of the lubricator. 
     SUMMARY OF INVENTION 
     Disclosed is an embodiment of a method of engaging sections of a pumping system. In one example embodiment the method includes providing a lower section of the pumping system, where the lower section has a connector with a bore on an upper surface that of the connector. The bore has a cross sectional area that decreases with distance away from its opening. The method further includes anchoring the lower section within production tubing disposed in a subterranean well and providing an upper section of the pumping system. The upper section includes a connector with a downward facing pin. The upper section is oriented into a designated azimuth for coupling engagement with the lower section. Orientation takes place by lowering the upper section onto the lower section and inserting the pin into the opening of the bore. The pin follows a generally circular path as it slides to a lowermost portion of the bore that positions the upper section at a designated azimuth for coupling the upper and lower sections. The upper section is engaged to the lower section when the upper section is oriented as desired. In one example, the lower section includes a lower pumping system with a splined drive shaft and the upper section has a driven shaft with splines. In an example embodiment, an annular coupling on the driven shaft has grooves formed on an inner surface and when the upper section is at the designated azimuth, the splines on the drive shaft are aligned with the grooves in the coupling so that the drive shaft can be inserted into a lower end of the coupling. Optionally, fluid can be vented from inside of the coupling when the drive shaft inserts into the coupling. In another alternative embodiment, fluid is pumped from the wellbore by rotating the drive shaft to rotate the driven shaft via the coupling to pressurize the fluid in the lower section and the upper section. An upward force can optionally be applied onto the upper section to disengage the upper section from the lower section. Alternatively, additional sections can be stacked onto the upper section. 
     Also disclosed is an embodiment of an electrical submersible pumping (ESP) system. In one example, the ESP system is made up of a lower tandem selectively anchored inside of production tubing that is disposed in a wellbore. A drive shaft is included in the lower tandem that has an end that projects past the lower tandem and splines on its outer surface. In this example, a connector is provided on an upper end of the lower tandem has an upward facing bore with an cross sectional area that decreases with distance away from an opening of the bore. An upper tandem is set on the upper end of the lower tandem that has a driven shaft inserted into an annular coupling. A connector is provided on a lower end of the upper tandem that has a strategically located pin that points downward. In this example, when the upper tandem lands on the lower tandem and the pin is inserted into the opening of the bore, the pin slides along a side of the bore to a designated azimuth and aligns the grooves in the coupling with splines on the drive shaft as the coupling slides over the drive shaft. In one alternative, the splines on the drive shaft have an upper end with a pointed tip. A vent is optionally formed through a sidewall of the coupling. In one alternate embodiment, the connectors are threadingly mounted on the respective upper and lower ends of the lower and upper tandems, and the pin and bore are adjacent respective outer edges of the connectors on the upper and lower tandems. One alternate embodiment includes a plurality of upward facing bores on the connector on the lower tandem and arranged proximate one another. Optionally, a plurality of downward facing pins are on the connector on the upper tandem. In this example, when the upper tandem is lowered onto the lower tandem, the pins engage an opening of one of the bores. Alternatively, the bores are disposed proximate an outer surface of the connector on the lower tandem, and the pins are disposed proximate an outer surface of the connector on the upper tandem. 
     Also provided herein is a through tubing electrical submersible pumping (ESP) system, that in one example embodiment includes a lower tandem pump in selective anchoring within a string of production tubing disposed in a wellbore. A drive shaft with splines is included with the lower tandem pump. A shaft coupling is also included that has an axial passage and grooves formed axially along a sidewall of the passage. The ESP system also includes an upper tandem pump in fluid communication with the lower tandem pump and coupled to an upper end of the lower tandem pump having a driven shaft with a lower end engagedly inserted into the shaft coupling. Connectors are provided on the respective upper and lower ends of the lower and upper tandem pumps for azimuthally orienting the upper tandem so the grooves in the shaft coupling align with splines on the drive shaft as the upper tandem is lowered on to the lower tandem. In one example embodiment, the means for orienting the upper tandem include a series of bores that are disposed along a substantially circular path on an upper surface of the lower tandem. In this example, the path is proximate an outer periphery of the lower tandem. Optionally, the means for orienting the upper tandem includes downwardly pointing pins provided along a substantially circular path on a lower surface of the upper tandem. In this embodiment the path is proximate an outer periphery of the upper tandem. Thus when lowered into the bores, the pins slide in a circular path along a side of the bores to a lowermost position and in a designated azimuth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side sectional view of a connection assembly for a submersible pumping system disposed in a wellbore. 
         FIG. 2  is a sectional perspective view of an embodiment of the connection assembly of  FIG. 1 . 
         FIG. 3  is a side partial section view of tandem submersible pumping systems being coupled together. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. 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. 
       FIG. 1  is a side sectional view of a connection assembly  18  for connecting a lower tandem  20  to an upper tandem  22 , which make up a part of a through tubing conveyed (TTC) pumping system  24 . A drive shaft  26  is shown coaxially within the lower tandem  20  and held in place by a bearing assembly  27 . The drive shaft  26  is mechanically coupled to a driven shaft  28  shown set coaxial within the upper tandem  22 . An annular coupling  30  has a lower end and in which an upper end of the drive shaft  26  is inserted. A lower end the driven shall  28  is shown inserted in an upper end of the annular coupling  30 . In the example of  FIG. 1 , the drive shaft  26  and driven shaft  28  are maintained substantially coaxial by the annular coupling  30 . Splines  32  shown extending substantially lengthwise along the upper end of the drive shaft  26  mate with grooves or channels  33  provided lengthwise on an inner surface of the coupling  30 . Similarly, splines  34  are formed lengthwise along the lower end of the driven shaft  28  and encounter grooves or channels (not shown) lengthwise in the coupling  30  thereby mechanically affixing the drive shaft  26  with the driven shaft  28 . An optional set screw (not shown) may be included for attaching the coupling  30  to the driven shaft  34 . A vent  35  is optionally formed through a sidewall of coupling  30 . 
     In the example of  FIG. 1 , the upper end of the splines  32  narrow to an upward facing edge to form points  38 . The reduced cross sectional area of the points  38 , over that of a “non-pointed” and planar spline embodiment, eases mounting the coupling  30  onto the upper end of the drive shaft  32  by removing potentially interfering structure. The pointed upper ends minimize potential contact surfaces to reduce potential surface contact resistance when inserting the drive shaft  32  into the coupling  30 . 
     On the lower end of the upper tandem  22  is a sealing stinger  40 , which is illustrated as an annular extension and protruding a distance within the opening on the upper end of the lower tandem  20 . The stinger  40  of  FIG. 1  has an outer diameter configured for sealing contact with the inner circumference of the opening within the lower tandem  20 . Optionally, seals  42  shown on the outer periphery of the sealing stinger  40  may be included to ensure a sealing contact between the lower and upper tandems  20 ,  22 . As shown in  FIG. 1 , the periphery of the stinger  40  is set radially inward from the outer circumference of the upper tandem  22 , thereby defining a downward facing annular shoulder  44  on the outer circumference of a connector  520  of the upper tandem  22 . As shown in the coupled configuration of  FIG. 1 , the annular shoulder  44  lies in a plane that is substantially perpendicular to an axis AX of the connection assembly  18 . The annular shoulder  44  is shown resting on an upper end of a connector  56  that makes up the upper end of the lower tandem  20 . 
     Still referring to  FIG. 1 , cylindrically shaped pins  48  are shown projecting downward from within the annular shoulder  44 . Alignment holes or bores  50  are formed within the connector  56  and substantially aligned with the axis AX of the connection assembly  18  and the pins  48 . Thus, when the upper and lower tandems  20 ,  22  are coupled; the pins  48  are inserted within the alignment bores  50 . In the embodiment of  FIG. 1 , the lower ends of the alignment bores  50  are open to the an annular recess  46  formed on the exterior of the connector  56 . 
     Referring now to  FIG. 2 , the pumping assembly  24  of  FIG. 1  is shown in a perspective and partial sectional view. The assembly  24  of  FIG. 2  is not in a coupled configuration; instead the upper tandem  22  is only partially inserted in with the lower tandem  20  and illustrates an example stage of coupling or decoupling the upper and lower tandems  20 ,  22 . More specifically, the lower end of the sealing stringer  40  is inserted within the opening of the lower tandem  20  and with its lower end just past the upper end of the connector  56 . Accordingly, the coupling  30 , which is secured to the driven shaft  28  by the set screw is still above the upper end of the drive shaft  26 . Additionally, the pins  48  are above the alignment bores  50  and out of contact with the connector  56 . The embodiment of  FIG. 2  illustrates the lower end of the upper tandem  22  to include a selectively attachable male connector  52  that can be threadingly attached to a housing  54  that houses the upper tandem  22 . Thus in one example embodiment, the male connector  52  includes the sealing stinger  40 , annular shoulder  44 , and pins  48 . 
     Similar to the male connector  52 , the upper end of the lower tandem  20  is fitted with female connector  56 , which is threadingly coupled with housing  58  on the outer surface of the lower tandem  20 . The lower tandem  20  can be deployed or removed from a wellbore by coupling a wireline tool (not shown) with a profile  59  illustrated on an inner surface of the female connector  56  The female connector  56 , which is shown an annular element, may be replaced with other designs or configurations mounted on the end of the lower tandem  20 . As seen in the embodiment of  FIG. 2 , the alignment bores  50  project into the female connector  56  from a mating surface or annular shoulder  60  on the upper terminal end of the female connector  56 . Also, when the upper and lower tandems  20 ,  22  are attached, the annular shoulder  44  is in contact with the mating surface  60 . The alignment bores  50  are shown having a wide opening or circumferentially tapered entrance portion  50   a  at their upper section and have a cross sectional area that narrows with distance away from the mating surface  60  to define a lower section with cross sectional dimensions more approximate that of the pins  48  than the upper section of the bores  50 . Entrance portion  50   a  extends circumferentially along mating surface  60  a selected distance that is greater than a diameter or cross section of the lower, longitudinally extending portion of each alignment bore  50 . So that when the pin  48  is received within the opening  50   a  of the alignment bore  50 , the varying cross sectional profile of each entrance portion  50   a  of each bore  50  guides the lower end of each pin  48  along a helical path so that the grooves or channels within the coupling  30  are aligned with the splines  32  on the drive shaft  26 . Strategically positioning the pins  48  and profiling of the bores  50  enables alignment and coupling when the upper tandem  22  is landed onto the lower tandem  20 , even when the pins  48  are azimuthally offset from the lower section of the bores  50 . The pin  48  or pins  48  of  FIGS. 1 and 2  could be a single pin or multiple pins. The alignment of the pins  48  and the splines  32  are independent as the tandems  20 ,  22  are made up. The upper tandem  22  may rotate in one direction, such as clockwise, while the coupling  30  and splines  32  may rotate in an opposite, or counter-clockwise direction, depending on the respective initial orientation of the upper tandem  22 , coupling  30 , and splines  32 . 
       FIG. 3  is a partial sectional view of an example of a pumping system  24  set within tubing  62  that is deployed within a wellbore. In the example of  FIG. 3 , the lower tandem  20  represents a stand alone through tubing conveyed pumping system set within the tubing  62  and having a packer  64  set in the annular space between the lower tandem  20  and inner surface of the tubing  62 . A casing  66  circumscribes the tubing  62  within the wellbore, wherein the tubing  62  and casing  66  each are supported from the surface from a wellhead assembly  68 . The lower tandem  20  of  FIG. 3  is made up of a motor section  70  having a motor for driving the drive shaft  26  ( FIGS. 1 and 2 ), a seal section  72  set on an upper end of the motor section  70 , and a pump section  74  on the upper end of the seal section  72 . In the embodiment of  FIG. 3 , the female connector  56  is mounted on an upper end of the pump section  74 . Further illustrated in the example of embodiment of  FIG. 3  is a fluid inlet  76  on the housing of the pump section  74  for receiving wellbore fluid to be pumped. 
     The upper tandem  22  is shown as a pump section  74 A similar to the pump section  74  of the lower tandem  20 . Accordingly, the male connector  52  is shown mounted on a lower end of the pump section  74 A. The upper tandem  22  of  FIG. 3  is shown being deployed within the tubing  62  from a wireline  78  that can be used for raising and lowering the pump assembly  24 . In the example of  FIG. 3 , the wireline  78  is shown suspended through the wellhead assembly  68 . Assembling a multi-tandem submersible pump using the connection systems provided herein allows for staging of pumps within the well bore and without the need of staging above the wellhead  68 . 
     In one example embodiment of operation, the lower tandem  20 , with an intake surface installed can be deployed in the tubing  62  and anchored therein, such as with the packer  64 . In this example, the collar  46  is provided on an upper end of the lower tandem  20  with alignment bores  50  facing upward. The upper tandem  22  can then be lowered onto the anchored lower tandem  20 , where the male connector  52  with downward facing pins  48  can engage the bores  50  to rotate the upper tandem  22  into a designated azimuth so that the coupling  30  on the driven shaft  28  can align with and engagingly slide over the drive shaft  26  to fully couple the lower and upper tandems  20 ,  22 . In addition to azimuthally orienting the upper tandem  22 , the pins  48  can also prevent the tandems  20 ,  22  from rotating with respect to one another during pumping operations. Alternatively, a series of middle tandem pumps (not shown) can be set on the lower tandem  20  for purposes of adding to the stage count. An upper tandem pump can be set on the middle tandem pumps. A pressure segregating apparatus can be strategically disposed in the annular space between the pumps and wellbore. Further, an anchoring device, such as like a packer assembly, can be set on the pumps. 
     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the pins  48  could have lower ends that are pointed. Optionally, the pins  48  could have shapes or profiles that vary along their lengths. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.