Abstract:
Devices and methods for reversibly securing first and second component subs of submersible well pump assembly. First and second component subs are provided with connection end portions which are placed into a sealed abutting relation. A connecting collar is threaded onto the first component sub. A locking groove on the first component sub receives a locking dog therein.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to component connections. In particular aspects, the invention relates to component connections that are useful to interconnect components of an electrical submersible pump of the type used in wellbores and the like. 
     2. Description of the Related Art 
     Electrical submersible pumps (“ESP”s) are commonly used for production of hydrocarbon fluids from oil and gas wells. A typical ESP includes a number of modular subassemblies that are housed within separate subs, or sections, that are secured to one another to function as a unit. An exemplary ESP, for example, would include a motor section, pump section, seal section and might also include a gas separator section. In order to interconnect these sections, individual subs are traditionally provided with flanged end portions. A multiplicity of threaded screws are passed through holes in the flange of one sub into threaded holes in a mating sub, thereby securing the subs together. The width of the flange must be sufficient to accommodate the connecting bolts and, as a result, the interior diameter of the flow passage within the two components being interconnected must be undesirably decreased. 
     U.S. Pat. No. 6,557,905 issued to Mack et al. describes techniques for interconnecting ESP components without the use of nuts and bolts commonly found in such connections. The &#39;905 patent is owned by the assignee of the present application and is herein incorporated by reference. Use of this method provides less of an interior restriction than techniques that use bolts. It is also stronger and uses fewer separate components. Over time, however, the tightness of the connection may become undesirably reduced. 
     SUMMARY OF THE INVENTION 
     The present invention provides systems and methods for reversibly interconnecting two individual components. In particular embodiments, the invention provides systems and methods for reversibly interconnecting separate subs, or sections, of an ESP. The described component connections do not require bolts and are resistant to loosening that might result from vibration of the connection. In addition, component connections in accordance with the present invention can be used without the need to significantly restrict the interior openings of the components being connected as is the case of prior techniques, such as that described in the &#39;905 patent discussed above. 
     Exemplary connections are described which include a first tubular component that is reversibly affixed to a second tubular component. The first tubular component includes a pin-type threaded connection. The second tubular component preferably includes an annular notch. Preferably also, a retaining ring is disposed within the annular notch. An annular locking groove is formed within at least one of the tubular components. 
     A connection collar is used to reversibly affix the first and second components together. Exemplary connection collars are described that include an annular portion and an angularly segmented portion. The connection collar includes an internally threaded portion that is shaped and sized to threadedly engage the pin-type threaded connection of the first tubular component. One axial end of the connection collar has a plurality of axial slots formed therein to form separate fingers that can be deflected outwardly. A dog is formed on the distal end of the fingers and is shaped and sized to reside within the annular locking groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and other aspects of the invention will be readily appreciated by those of skill in the art and better understood with further reference to the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawings and wherein: 
         FIG. 1  is a side, cross-sectional view of an exemplary component connection in accordance with the present invention wherein two tubular components are unconnected to one another. 
         FIG. 2  is a side, cross-sectional view of the component connection shown in  FIG. 1 , now with both tubular components connected. 
         FIG. 3  is a side, cross-sectional view of an exemplary connection collar used with the component connection shown in  FIGS. 1 and 2 . 
         FIG. 4  is a side, cross-sectional view of an alternative exemplary component connection in accordance with the present invention wherein the two tubular components are unconnected to one another. 
         FIG. 5  is a side, cross-sectional view of the component connection shown in  FIG. 4 , now with both tubular components connected. 
         FIG. 6  is a side, cross-sectional view of an exemplary connection collar used with the component connection shown in  FIGS. 4 and 5 . 
         FIG. 7  is a side view of an exemplary ESP which incorporates component connections in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  depict an exemplary component connection  10  which includes a first tubular component  12  and a second tubular component  14  that are being interconnected in an end-to-end fashion. A central axial flowbore  16  is defined within the first tubular component  12 . It is noted that the first tubular component  12  includes an axial end face  18  and a pin-type threaded portion  20  that is proximate the end face  18 . An annular lip  22  preferably projects outwardly from the end face  18 . 
     The second tubular component  14  includes a central axial flowbore  24  along its length and presents a connecting axial end portion, generally indicated at  26 . The axial end portion  26  includes an external annular notch  28  within which is seated a retaining ring  30 . In certain embodiments, the retaining ring  30  can be a C-ring that is snapped into the notch  28 . Preferably, the end portion  26  also carries O-ring fluid seals  32 , of a type known in the art. An external annular groove  34  is formed within the end portion  26 . 
     A connection collar  36  surrounds the end portion  26 . Portions of the connection collar  36  are better appreciated with reference to  FIG. 3 . The exemplary connection collar  36  includes an annular portion  38  and an angularly segmented portion  40 . The annular portion  38  includes interior threads  42  that are shaped and sized to be complementary to the threads  20  of the first tubular component  12 . The segmented portion  40  includes axial slots  44  formed within which separate the end of the segmented portion  40  into fingers  46 . A dog  48  projects radially inwardly from the axial end of each finger  46 . A stop shoulder  50  is defined within the connection collar  36 . 
       FIG. 1  depicts the connection  10  in an unconnected configuration while  FIG. 2  shows the first and second tubular components  12 ,  14  connected by the connecting collar  36 . In the unconnected configuration, the fingers  46  of the connecting collar  36  are spread apart as the dogs  48  are located out of the locking groove  34 . To assemble the connection  10 , the end face  18  of the first tubular component  12  is placed into an abutting relation with the end face  52  of the end portion  26  of the second tubular component  14 . The lip  22  now radially surrounds the end portion  26  of the second tubular component  14  so that a fluid tight seal is provided to isolate the flowbores  16 ,  24  by O-ring seals  32 . The connection collar  36  is threaded onto the pin-type threading of the first tubular component  12 . As the collar  36  is tightened, the dogs  48  of the fingers  46  will be drawn upwardly and snap into the annular locking groove  34 . The stop shoulder  50  of the connection collar  36  will be brought into contact with the retaining ring  30  to ensure that the first and second tubular components  12 ,  14  are drawn together. The presence of the dogs  48  within the annular locking groove  34  will prevent loosening of the connection  10  as a result of vibration or other forces. Thus, the component connection  10  is vibration-resistant. 
     The connection  10  is reversible. The dogs  48  and the locking groove  34  preferably have tapered sides, so that the dogs  48  and groove  34  have a generally triangular or V-shaped cross-section. In order to disconnect the first and second tubular components  12 / 14  from one another, unscrewing torque force is supplied to the collar  36  to cause the dogs  48  to ramp up out of the groove  34  and permit the disengagement of the collar  36  from the upper tubular component  12 . Then, the connecting collar  36  can be rotated to unthread and thereby release the first and second tubular components  12 ,  14  from one another. Yet, the spring tension of the fingers  46  hold the dogs  48  into the groove  34  and prevent the loosening of the collar  36  due to vibratory forces and the possible unintended separation of tubular components  12  and  14 . 
       FIGS. 4-6  illustrate an exemplary alternative component connection  10 ′ in accordance with the present invention. The alternative component connection  10 ′ is constructed and operates in the same manner as the component connection  10  described previously, except where indicated otherwise. The connection  10 ′ includes a first tubular component  12 ′ and a second tubular component  14 ′. In this embodiment, the locking groove  34 ′ is formed within the first tubular component  12 ′ rather than the second tubular component  14 ′. 
     Features of the connecting collar  36 ′ are depicted in greater detail in  FIG. 6 . As with the connecting collar  36  described previously, the connecting collar  36 ′ includes an annular portion  38 ′ and an angularly segmented portion  40 ′. Axial slots  44  in the angularly segmented portion  40 ′ forms fingers  46  that can be deflected radially outwardly. Dogs  48  are formed on the distal portions of the fingers  46  and are shaped and sized to reside within the locking groove  34 ′. 
       FIG. 4  illustrates the component connection  10 ′ in an unconnected condition wherein the first and second tubular components  12 ′ and  14 ′ are not connected.  FIG. 5  shows the tubular components  12 ′ and  14 ′ in a connected condition. In order to connect the tubular components  12 ′,  14 ′, the end faces  18 ,  52  of the tubular components  12 ′,  14 ′ are placed in abutting relation, as shown in  FIG. 5 . The connecting collar  36 ′ is interthreaded with the first tubular component  12  and the dogs  48  of the fingers  46  will flex radially outwardly to pass over threads  20  and then snap into the locking groove  34 ′. The connection  10 ′ is vibration resistant due to the presence of the dogs  48  within the locking groove  34 ′ which discourages reverse rotation of the connecting collar  36 ′. As with the previous component connection  10  described previously, the dogs  48 ′ and groove  34 ′ are preferably tapered so that dogs  48 ′ and groove  34 ′ have a generally triangular or V-shaped cross-section. 
     The connection  10 ′ is reversible. In order to disconnect the first and second tubular components  12 ′,  14 ′, the fingers  46  are deflected radially outwardly so that the dogs  48 ′ are removed from the locking groove  34 ′. The outward deflection is accomplished by applying torque to the collar  36 ′ to unscrew it. The tapered faces of the locking dogs  48 ′ and the mating groove  34 ′ force the collar fingers  46  to deflect and the dogs  48 ′ to ride out of the groove  34 ′, thus permitting the collar  36 ′ to unscrew and disengage the threads of the mating sub. The springy nature of the collar fingers  46  prevents vibratory forces from causing the collar  36 ′ to loosen or disengage, but permits normal disassembly torque applied to the collar  36 ′ to disengage the collar  36 ′ from the mating sub. 
     It should be appreciated that the invention also provides a vibration-resistant electric submersible pump (ESP) assembly that includes connection components in accordance with the present invention.  FIG. 7  illustrates an exemplary ESP assembly  60  which is suspended within a wellbore  62  by running string  64  and which includes a number of separate subs or components that are secured to one another using component connections  10 / 10 ′ in accordance with the present invention. The exemplary ESP assembly  60  includes a pump sub  66  with pump inlets  68 . The ESP assembly also includes a seal section sub  70 . A motor section sub  72  is disposed below the seal section sub  70 . Power conduit  74  provides power to the motor section sub  72 . Component connections  10  or  10 ′ are being used to interconnect the pump sub  66  with the seal section sub  70  and the seal section sub  70  with the motor section sub  72 . It is noted that one could utilize threaded adapters to retrofit component connections  10  or  10 ′ onto threaded components within an ESP assembly, thereby providing vibration-resistance to the ESP assembly. It should be recognized that the invention provides a method for reversibly connecting first and second component subs of a submersible pump assembly. 
     Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.