Abstract:
An electric motor of an electric submersible pump is electrically isolated from a power conduit for diagnostic testing of the power conduit and wet connection components in place within a wellbore. The electric motor is electrically connected to the power conduit through a wet connection assembly having motor leads in electrical connection with a transfer contact and a receptacle assembly disposed on a tubing string having a supply contact electrically connected to the power conduit. Electric power flows through the power conduit, through the supply contact, through the transfer contact, and through the motor leads to the motor. The supply contact and the transfer contact are separated by a sliding sleeve that hydraulically inserts between the contacts, insulating the transfer contact and grounding the supply contact for testing. The contacts may also be separated by a relative rotation of the assemblies that grounds the supply contact for testing.

Description:
[0001]    This application claims priority to and the benefit of co-pending U.S. Provisional Application No. 61/413,716, by Tetzlaff et al., filed on Nov. 15, 2010, entitled “Isolating Wet Connect Components for Deployed Electrical Submersible Pumps,” which application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to downhole pumping systems submersible in well bore fluids. More specifically, the present invention provides for isolating electrical wet connect components for a submersible pump system to allow for diagnostic, operational, and other independent tests. 
         [0004]    2. Brief Description of Related Art 
         [0005]    Submersible pumping systems are often used in hydrocarbon producing wells for pumping fluids from within the wellbore to the surface. These fluids are generally liquids and include produced liquid hydrocarbon as well as water. One type of system used in this application employs an electrical submersible pump (ESP). ESPs are typically disposed at the end of a length of production tubing and have an electrically powered motor. Often electrical power may be supplied to the pump motor via a power cable. Normally, the power cable is strapped to the tubing and lowered along with the pump and the tubing. Typically, the pumping unit is disposed within the well bore just above where perforations are made into a hydrocarbon producing zone. ESP&#39;s typically require periodic retrieval for scheduled maintenance or repair. This usually entails removing the tubing and the power cable, which is secured alongside the tubing. Pulling and re-running the tubing is time consuming and pulling and reusing the power cable creates mechanical wear and can sometimes damage the cable. 
         [0006]    Lowering the pumping assembly inside the production tubing avoids the need for pulling the tubing to retrieve the pump. Some well completions run the power cable on the tubing exterior and the pump through the tubing. The pump stacks into engagement with electrical contacts provided on the lower end of the power cable, in what is called a wet connection. These wet connections rely on component assemblies that create an electrical connection between an insertable/retrievable pumping system and a semi-permanent power conduit run with the production tubing. Once the wet connection is made, the completion or intervention devices or machines used to install the pumping system are moved away from the well. When the pumping system encounters problems, such as when the system becomes rotationally challenged, the pumping system and/or the power conduit must be pulled from the well, inspected, and remediated to repair the damaged component. Pulling both the pumping system and the power conduit requires a considerable expenditure of time and money. Thus, a system or apparatus that allowed for downhole isolation and testing of the pumping system and power conduit to determine the problem area so that only the failed component may be pulled and repaired is desirable. 
       SUMMARY OF THE INVENTION 
       [0007]    These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention that provide a method for isolating wet connect components for diagnostic testing of deployed systems. 
         [0008]    In accordance with an embodiment of the present invention, an electric submersible pumping system is disclosed. The system includes a pumping system deployable through a well tubing string and having a pump with a fluid inlet and a pump motor mechanically coupled to the pump. The system also includes a receptacle assembly adapted to be secured to a lower end of the tubing string, and a power conduit for placement alongside the tubing. The power conduit is electrically connected to a plurality of supply contacts formed within the receptacle assembly. The system further includes a wet connect assembly coupled to the pumping system, having a plurality of transfer contacts and having motor lead lines electrically connecting the plurality of transfer contacts to the pump motor. The pumping system is deployable through the tubing string so that the wet connect assembly lands in the receptacle assembly with the supply contacts and the transfer contacts electrically connected to each other to supply electrical power through the power conduit to the motor. The system also includes an isolation assembly within the receptacle assembly that is selectively movable from a power transfer position to an isolation position to isolate the transfer contacts from the supply contacts for diagnostic testing of the power conduit. 
         [0009]    In accordance with another embodiment of the present invention, an electric submersible pumping system is disclosed. The system includes a well tubing string disposed within a wellbore. The system further includes a pumping system deployable through the well tubing string and having a pump with a fluid inlet and a pump motor mechanically coupled to the pump. The system also includes a receptacle assembly adapted to be secured to a lower end of the tubing string, and a power conduit for placement alongside the tubing. The power conduit is electrically connected to a plurality of supply contacts formed within the receptacle assembly. The system further includes a wet connect assembly coupled to the pumping system, having a plurality of transfer contacts and having motor lead lines electrically connecting the plurality of transfer contacts to the pump motor. The pumping system is deployable through the tubing string so that the wet connect assembly lands in the receptacle assembly with the supply contacts and the transfer contacts electrically connected to each other to supply electrical power through the power conduit to the motor. The system also includes a hydraulic isolation assembly within the receptacle assembly that is selectively movable from a power transfer position to an isolation position to isolate the transfer contacts from the supply contacts for diagnostic testing of the power conduit. 
         [0010]    In accordance with yet another embodiment of the present invention, a method for powering an electric motor of an electric submersible pump is disclosed. The method provides a receptacle assembly on a lower end of a tubing string and having a plurality of supply contacts on an inner diameter of the receptacle assembly. The method deploys the tubing string in a well and extending a power cable from the receptacle assembly alongside the tubing string. The method also provides a pump assembly with a wet connect assembly having a plurality of transfer contacts formed on an outer diameter .of the wet connect assembly and motor lead lines electrically connecting the transfer contacts to a pump motor. The method lowers the pump assembly through the tubing string and engages the transfer contacts with the supply contacts. The method supplies electrical power to the pump motor through the power conduit, the supply contacts, the transfer contacts, and the motor lead lines to operate the pump assembly and to test integrity of the power cable: The method also remotely actuates an isolation assembly formed within the receptacle assembly to separate the transfer contacts from the supply contacts without withdrawing the pump assembly from the tubing string. 
         [0011]    An advantage of the disclosed embodiments is that they provide a method to isolate wet connection components for diagnostic testing in place within a wellbore. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained, and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and are therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments. 
           [0013]      FIG. 1  is a vertical cross-sectional view of an electrical submersible pump assembly deployed in tubing in a wellbore. 
           [0014]      FIG. 2  is a vertical cross-sectional view of an assembly according to the present invention, with the wet connect components of the electrical submersible pump of  FIG. 1  isolated from each other. 
           [0015]      FIG. 2A  is an enlarged view of a portion of the structure circled and identified by reference numeral  2 A in  FIG. 2 . 
           [0016]      FIG. 3  is a vertical cross-sectional view of an assembly according to the present invention with the wet connect components of the electrical submersible pump of  FIG. 1  in electrical connection with each other. 
           [0017]      FIG. 3A  is an enlarged view of a portion of the structure circled and identified by reference numeral  3 A in  FIG. 3 . 
           [0018]      FIG. 4  is a horizontal cross-sectional view of lower portions of an alternate assembly according to the present invention taken along the line  4 - 4  of  FIG. 1  with the wet connect components of the electrical submersible pump of  FIG. 1  in electrical connection with each other. 
           [0019]      FIG. 5  is a horizontal cross-sectional view of upper portions of the alternate assembly of  FIG. 4  according to the present invention taken along the line  5 - 5  of  FIG. 1 . 
           [0020]      FIG. 6  is a horizontal cross-sectional view of the alternate assembly depicted in  FIG. 4  according to the present invention taken along the line  4 - 4  of  FIG. 1 , but with the wet connect components of the electrical submersible pump moved to positions isolated from each other. 
           [0021]      FIG. 7  is a horizontal cross-sectional view of upper portions of the alternate assembly depicted in  FIG. 6  taken along the line  5 - 5  of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the invention. 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, and the prime notation, if used, indicates similar elements in alternative embodiments. 
         [0023]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Additionally, for the most part, details concerning ESP operation, construction, and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons skilled in the relevant art. 
         [0024]    In the drawings,  FIG. 1  is a partial vertical cross-sectional view of an electrical submersible pump or ESP system P positioned at a depth of interest in a well borehole  10  lined with a casing  12 . The pump causes upward movement of formation fluid as indicated by arrows  14  entering the well borehole  10  from perforations  16  which have been formed in a subsurface formation  18  through the casing  12 . The formation fluid in well borehole  10  is delivered for pumping to the pump P via inlet passages  20  in a deployed outer body or outer housing  22  and then onto pump inlets for pumping by a pump motor  24  in the conventional manner. 
         [0025]    An inserted assembly  30  attached below the pump P in the outer housing  22  is illustrated fully landed within a conductor shoe or receptacle assembly  32  formed at a lower end of the deployed outer housing  22 . The inserted assembly  30  when fully landed within the receptacle assembly  32  anchors the pump system P for pumping operations by the pump motor  24  upwardly through production casing or tubing when electrical power is furnished. 
         [0026]    The inserted assembly  30  when fully landed has its weight, along with the weight of the pump P, supported by the receptacle assembly  32 . The inserted assembly  30  is landed and positioned within the receptacle assembly  32  by engaging a set of vertically longitudinally extending keys  36  which fit within vertically extending slots  40  in a corresponding set of profiled channels  38  on an adapter head  42 . If desired, a single key  36 , slot  40 , and channel  38  may be used. In the illustrative embodiment, three keys  36  are provided, but it should be understood that other numbers of such components could be included. 
         [0027]    Preferably the opening or openings on the channel(s)  38  are circumferentially disposed about the periphery of the inserted assembly  30  and are profiled with sufficient width so that the key or keys  36  may be fitted firmly therein. As the inserted assembly  30  is lowered to the fully landed position, the tapered surfaces of the channel  38  slide on upper surface portions of the key  36 , which rotates the inserted assembly  30 . The tapered surfaces of channel  38  slide on the key  36  during further downward movement, until the key  36  top is aligned and fitted within the constant width slot portion  40  in the fully landed position. At this point, the inserted assembly  30  drops to insert the key or keys  36  into the corresponding constant width slot portion  40  of the profiled channel  36 . The fitted coupling of keys  38  and slots  40  when engaged prevents relative rotation between the inserted assembly  30  and the outer housing  22 . 
         [0028]    A plunger  50  and associated seal  52  mounted at a lower end of the inserted assembly  30  is positioned in a lower polished bore  54  formed in the outer housing  22 . Optionally, a hydraulic motor  55  may be secured to a lower end of the inserted assembly  30  and adapted to rotate the inserted assembly  30  as described in more detail with respect to  FIG. 4-7 . As shown in  FIG. 1 , an upper polished bore  56  is formed in the outer housing  22  above the plunger  50  and the lower polished bore  54 . The upper and lower polished bores in the outer housing  22  form a receiving chamber for the plunger  50  of the inserted assembly  30 . 
         [0029]    A suitable number of electrical supply conductors  60  extend downwardly in a conduit  62  and through a connection fitting  64  to electrically connect with a wet connect power supply contact  66 . In the illustrative embodiment, three conductors  60  and corresponding wet connect power supply contacts  66  are provided in order that multiphase electrical power may be provided to the pump motor  24 . It should be understood, however, that other numbers of such conductors and contact components could be utilized, if desired. 
         [0030]    The power supply contact  66  is mounted in an insulative sleeve  68  within an insulative sleeve  69  in the inserted assembly  30 . The wet connect power supply contact  66  extends inwardly and initially forms an electrical connection with a corresponding wet connect power transfer contact  70  mounted on an outer surface of the inserted assembly  30 . The wet connect power transfer contact  70  is electrically connected by motor lead lines  72  to the pump motor  24  to furnish electrical power for pumping of formation fluids. Further details of the structure and arrangement of the wet connect electrical contacts  66  and  70  are set forth in commonly owned, co-pending U.S. patent application Ser. No. 12/413,243, filed Mar. 27, 2009, which is incorporated herein by reference. 
         [0031]    The present invention provides a new and improved apparatus and method for isolating the wet connect electrical contacts  66  and  70  from each other for diagnostic and testing purposes while the pump system P is deployed in situ in the well borehole. This can be done at lower cost and without requiring that rig equipment be used to remove the ESP from the well borehole  10 . 
         [0032]    The isolation of the inserted pump motor  24  and assembly  32  from the deployed housing  22  and conduits  62  may be accomplished by hydraulic pressure or by relative rotational movement between the inserted and deployed components, or both, as will be set forth. Electrical testing can then be performed for diagnosis and remediation, such as a determination of whether a problem is in the pump or in the continuity or integrity of the electrical conductor  60  installed with the production conduit or tubing. The present invention allows diagnostic testing of the production conduit without removal of the pumping system P and the production tubing connected therewith. 
         [0033]    The hydraulic mechanism for isolation of the wet connect electrical contacts  66  and  70  from each other according to the present invention is illustrated schematically in  FIG. 1  and in detail in  FIGS. 2 and 3 . A conductive cylindrical electrical sleeve or collar assembly  80  ( FIG. 2 ) according to the present invention is located below the insulative sleeve  68  within the receptacle assembly  32 . Hydraulic seals  82  and  84  at upper and lower ends of the sleeve assembly  80  are provided for sealing between the sleeve  80  and an inner wall of the receptacle assembly  32 . A set of O-rings or comparable seals  86  and  88  are mounted along outer side walls of the sliding sleeve  80  to provide sealing therebetween during movement of the sliding sleeve  80 . A resilient mechanism such as a coil spring  90  is mounted in an annular chamber  92  of the sleeve  80 . The spring  90  is compressed when hydraulic pressure is introduced into the chamber  92  to move the sleeve upwardly from the position of  FIG. 3  where the electrical connection is made to the position of  FIG. 2  where the contacts  66  and  70  are electrically isolated. The hydraulic pressure applied in chamber  92  is furnished by one or more hydraulic lines  94  in fluid sealing connection with the chamber  92  and extending from the surface along the upper tubing or conduits and the outer housing  22 . In alternative embodiments, hydraulic pressure may be supplied from a hydraulic pressure source located at pumping system P. 
         [0034]    An inner insulative sleeve  96  is mounted or otherwise affixed or applied on an upper interior surface ( FIGS. 2A and 3A ) of the sleeve  80 . The insulative sleeve  96  is formed of a suitable non-conductive material. The material of sleeve  96  could be a thermoplastic such as polyether ether ketone or PEEK, although it should be understood that other non-conductive materials could be used as well. The sleeve  96  has a vertical extent equal to or greater than the vertical dimension of the power transfer wet connect electrical contacts  70  to prevent the contact from engagement with other electrical components during isolation as shown in  FIG. 2 . The outer surface of the sleeve  80  along its vertical extent is conductive. The outer upper portions of sleeve  80  remain in electrical contact with the multiphase wet connect power supply contacts  66  and thus provides a common electrical ground between the these contacts and their associated supply conductors. 
         [0035]      FIGS. 2 and 3  illustrate the elements of the sliding sleeve assembly  80  as the sliding sleeve assembly  80  separates and isolates the downhole deployed receptacle assembly  32  portion of the wet connection from the insertable assembly  30 . This separation/isolation allows electrical testing/diagnostics to be performed on the tubular deployed assembly.  FIG. 3  illustrates the normal operational state. When isolation for testing purposes is required, hydraulic fluid is supplied to the annular chamber  92 , moving the sliding sleeve assembly  80  axially upward, compressing the spring  90 . The upward axial movement of the sliding sleeve assembly  80  inserts the inner insulative sleeve  96  between the contacts  66 ,  70 , as shown in  FIG. 2 . The outer surface of the sleeve  80  remains conductive while the insulative inner sleeve  96  along the upper inner portions breaks the conductor interface when the sleeve  80  is moved to the position shown in  FIG. 2 . The outer surface of the sleeve  80  however maintains the completed circuit to electrical ground between the phases allowing the power conduit  62  components to be tested for uphole electrical continuity and integrity. Following diagnostic testing, hydraulic fluid pressure is removed from the annular chamber  92 , allowing the spring  90  to uncompress and return the sliding sleeve assembly  80  to the position of  FIG. 3 . In this manner, the electrical connection between contacts  66 ,  70  is restored. 
         [0036]    Another example of separating and isolating the electrical contact between the contacts  66  and  70  is illustrated in  FIGS. 4 through 7 . The inserted assembly  30  when oriented by the keys  36  in slots  40  aligns the contacts  66  and  70  in the manner described in relation to  FIG. 1 . The contacts  66  and  70  are urged into radial contact with each other in the manner described in co-pending U.S. patent application Ser. No. 12/413,243 previously referenced. Electrically engaging the contacts  66  and  70  provides a continuous path to flow electricity to the pump motor  24  from the power supply conductors  60 . 
         [0037]    As shown in  FIG. 4 , a set of circumferentially spaced electrically conductive grounding rods or bars  100  are mounted in grooves or slots formed in a housing sleeve  102 . The bars  100  are connected at the lower end of the assembled structure. The wet connect power transfer contacts  70  are mounted in vertically extending insulative channels  104  in housing sleeve  102  at circumferentially spaced positions between the grounding rods  100  and held in place by a retaining spring  108 . 
         [0038]      FIG. 5  illustrates upper portions of the inserted assembly  30  according to the present invention when the contacts  66  and  70  are aligned in the position illustrated in  FIG. 4 . According to the present invention, a recessed shift or rotational travel slot  110  extends around a portion of the periphery of an upper portion of the adapter head  42 . The slot  110  receives a vertically extending spline or rib  112  formed extending inwardly along an inner surface  114  of an upper portion of the outer housing  22 . The circumferential extent of the spline  112  is less than the circumferential extent of the slot  110  to permit relative rotational movement between the inserted body  30  and the deployed outer housing  22 . This permits corresponding rotational movement to separate and isolate the contacts  66  and  70 . Vertically extending travel limit surfaces or stops  116  and  118  are formed in the adapter head  42  on opposite sides of the slot  110  to serve as stop limits or contact surfaces for vertically extending travel limit or stop surfaces  120  and  122  on the spline  112 . 
         [0039]    In the structure as illustrated in  FIG. 4 , a shifting capability of 60° between the stop locations is provided. Relative rotational movement between the inserted assembly  30  and the deployed outer housing  22  to cause such shifting or relative movement of the spline  112  in the slot  110  can be driven by either hydraulic or electromechanically actuated devices. For example hydraulic motor  55  ( FIG. 1 ) may be supplied with hydraulic pressure from any suitable source to actuate and cause rotation of inserted assembly  30  relative to outer housing  22 . The relative rotational movement or shifting can be caused by movement of the inserted assembly  30 , the outer housing  22 , or both. 
         [0040]      FIGS. 6 and 7  illustrate the completion of the shifting motion after relative rotational movement as indicated by an arrow A. The electrical connection and transfer of electrical current between the contacts  66  and  70  is broken and the grounding bars  100  on the inserted assembly  30  are in electrical connection with the contacts  66 , as shown in  FIG. 6 , due to the rotation of the upper portions to the position shown in  FIG. 7  after a 60° rotational shift of spline  112  in the slot  110 . This maintains the completed circuit to electrical ground between the phases allowing the power conduit  62  components to be tested for uphole electrical continuity and integrity. Following diagnostic testing, a 60° rotational shift of the spline  112  in the slot  110  in the opposite direction restores the electrical connection between the contacts  66 ,  70 . 
         [0041]    Accordingly, the disclosed embodiments provide numerous advantages. For example, the disclosed embodiments provide a method to isolate wet connection components for diagnostic testing in place within a wellbore. 
         [0042]    It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or scope of the invention. Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.