Patent Publication Number: US-11021939-B2

Title: System and method related to pumping fluid in a borehole

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present document is based on and claims priority to U.S. Provisional Application Ser. No. 62/266,226, filed Dec. 11, 2015, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Hydrocarbon fluids such as oil and natural gas may be obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing geologic formation. After a wellbore is drilled, various forms of well completion components may be installed to enable control over and to enhance efficiency of producing fluids from the reservoir. In some applications, an electric submersible pumping system is deployed downhole into the wellbore and operated to produce well fluids. The electric submersible pumping system comprises a submersible pump powered by a submersible motor. Electric power is provided to the submersible motor via a power cable connected to the submersible motor and deployed downhole with the electric submersible pumping system. 
     SUMMARY 
     In general, a system and methodology facilitate use of a submersible pumping system, e.g. an electric submersible pumping system, deployed downhole in a borehole. A docking assembly comprises a docking station which has at least one electrical wet connector and is coupled to a receiving tubular. An electrical power cable is coupled to the docking station to enable electric power to be provided to the at least one electrical wet connector. The docking assembly is deployed downhole to a desired location in the borehole to enable coupling with the submersible pumping system simply by moving the submersible pumping system downhole into the receiving tubular and into electrical engagement with the electrical wet connectors. 
     However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and: 
         FIG. 1  is an illustration of an example of a submersible pumping system being deployed downhole into a borehole, e.g. a wellbore, for mechanical and electrical coupling with a docking assembly; 
         FIG. 2  is an illustration of an example of a docking assembly which may be positioned in the borehole to receive a submersible pumping system, according to an embodiment of the disclosure; 
         FIG. 3  is an illustration of an example of a submersible pumping system in the form of an electric submersible pumping system with a motor connector and electrical connectors oriented for engagement with a docking station of the docking assembly, according to an embodiment of the disclosure; 
         FIG. 4  is a top view of an embodiment of the docking station illustrating examples of electrical wet connectors, according to an embodiment of the disclosure; 
         FIG. 5  is an orthogonal view of an example of a motor connector mounted into the submersible pumping system and including electrical connectors oriented for engagement with electrical wet connectors of the docking station, according to an embodiment of the disclosure; 
         FIG. 6  is an illustration of an example of a submersible pumping system deployed downhole into an interior of the docking assembly and electrically engaged therewith, according to an embodiment of the disclosure; 
         FIG. 7  is a schematic illustration of a connection example between a power cable and electrical wet connector disposed in a docking station of the docking assembly, according to an embodiment of the disclosure; 
         FIG. 8  is an illustration of an example of individual conductors of a power cable coupled with corresponding electrical wet connectors of the docking assembly, according to an embodiment of the disclosure; 
         FIG. 9  is an orthogonal view of an example of a motor connector of the submersible pumping system, according to an embodiment of the disclosure; 
         FIG. 10  is a top view of an example of a docking station of the docking assembly, according to an embodiment of the disclosure; and 
         FIG. 11  is a schematic illustration of a docking assembly utilizing at least one centralizer to help centralize the motor connector of the submersible pumping system as the submersible pumping system is moved into the docking assembly, according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
     The present disclosure generally relates to a system and methodology which may be used to facilitate deployment and operation of a submersible pumping system in a borehole, e.g. a wellbore. For example, the system and methodology may be used in well applications to facilitate operation of electric submersible pumping systems. According to an embodiment, a docking assembly is constructed to be electrically powered via a power cable when deployed downhole into the borehole. The docking assembly enables easy engagement with the submersible pumping system at a downhole location. 
     According to an embodiment, the docking assembly comprises a docking station which has at least one electrical wet connector, e.g. a plurality of electrical wet connectors. The docking station also is coupled to a receiving tubular. An electrical power cable is coupled to the docking station to enable electrical power to be provided to the electrical wet connector(s). The docking assembly is deployed downhole to a desired location in the borehole to enable coupling with the submersible pumping system. For example, the docking assembly may be positioned downhole and subsequently the submersible pumping system is moved into engagement with the docking assembly. During coupling, the submersible pumping system may be moved downhole, through the receiving tubular, into the docking station, and into electrical connection with the electrical wet connectors. 
     In some embodiments, the electrical power cable may comprise at least one conductor, e.g. three conductors, individually connected with corresponding electrical wet connector(s) disposed within an interior of the docking station. According to an example, the docking station may comprise a coupling section and the electrical power cable may enter the docking station through the coupling section, e.g. through a seal in the coupling section. Within the docking station, the individual conductors of the power cable are separated (if more than one conductor is contained in the power cable) so that each conductor may be coupled into electric communication with its corresponding electrical wet connector. 
     The submersible pumping system may comprise a motor connector having a corresponding number of electrical connector(s) constructed for engagement with and electrical connection to corresponding electrical wet connector(s). By way of example, the motor connector may be positioned at a lower end of a submersible motor. Orienting features may be used to guide the electrical connectors into engagement with the corresponding electrical wet connectors as the submersible pumping system is deployed down into the docking assembly. 
     In a specific example, the orientation features may comprise a feature disposed on a lower end of the motor connector for engagement with an orienting feature of the docking assembly. However, the orientation features may be positioned at other locations along the motor connector/submersible pumping system. The orientation features cause rotation of the motor connector (and the submersible pumping system) about its axis as it is lowered into the docking assembly. For example, the orienting features of the motor connector and the docking assembly may be used in cooperation to align the electrical connectors of the submersible pumping system with the electrical wet connectors of the docking assembly to form the desired electrical connection. 
     The docking assembly enables electrical power to be provided downhole to the downhole docking assembly independently of the submersible pumping system. The submersible pumping system, e.g. electric submersible pumping system, may then simply be deployed downhole and placed into electrical communication with the power cable via docking at the downhole docking assembly. Consequently, the submersible pumping system may be deployed, serviced, and/or replaced without routing a dedicated power cable downhole with the submersible pumping system. 
     Referring generally to  FIG. 1 , an embodiment of a submersible pumping system  20  is illustrated as being deployed downhole into a well  22  for mechanical and electrical coupling with a docking assembly as discussed in greater detail below. By way of example, the submersible pumping system  20  may comprise or be in the form of an electric submersible pumping system  24 . Additionally, the submersible pumping system  20  may comprise a variety of components depending on the particular application or environment in which it is used. 
     In the illustrated example, the electric submersible pumping system  24  comprises a submersible pump  26 , a submersible electric motor  28 , and a motor protector  30 . The submersible pump  26  is operatively coupled with the submersible motor  28  by, for example, a driveshaft. Depending on the operation, electric submersible pumping system  24  may comprise other components such as a gauge section  32  and an expansion joint  34 . In some embodiments, submersible pump  26  may be a centrifugal pump having two or more stages, e.g. compression stages, with impellers rotated by submersible motor  28 . The net thrust load, e.g. down thrust load, resulting from operation of submersible pump  26  may be resisted by, for example, a thrust bearing positioned at a desirable location along motor protector  30 . 
     Well  22  may comprise a borehole  36 , e.g. a wellbore, drilled into a geologic formation  38  containing a desirable production fluid  40 , e.g. petroleum. The borehole  26  may be lined with a tubular well casing  42 , and perforations  44  may be formed through the well casing  42  to enable flow of fluids between the surrounding formation  38  and the wellbore  36 . The electric submersible pumping system  24  may be deployed downhole into borehole  36  via a conveyance system  46  and into engagement with a docking assembly as described in greater detail below. By way of example, the conveyance system  46  may comprise tubing  48 , such as coiled tubing, connected to submersible pump  26  by a suitable connector sub. However, the conveyance system  46  also may comprise wireline, slick line, or other suitable conveyance systems able to convey the submersible pumping system  20  downhole from a surface location  52 . 
     During operation, electrical power is supplied to submersible motor  28  via a motor connector  54  as explained in greater detail below. The submersible motor  28  is powered to, in turn, power submersible pump  26  via a suitable driveshaft. Operation of submersible pump  26  causes fluid  40  in borehole  36  to be drawn into the submersible pumping system  20  through a pump intake  56 . The fluid  40  is pumped upwardly to a surface collection location or to another suitable collection location. In the illustrated embodiment, for example, the fluid  40  may be pumped upwardly through an interior of tubing  48  to a desired collection location at surface  52 . 
     With reference to  FIGS. 1 and 2 , an embodiment of a docking assembly  58  is illustrated for use in cooperation with the submersible pumping system  20 . For example, the docking assembly  58  may be constructed to receive electric submersible pumping system  24  and to provide power to electric submersible pumping system  24  via motor connector  54 . In this example, the docking assembly  58  comprises a docking station  60  internally configured for receipt and electrical connection with motor connector  54 . Motor connector  54  may be coupled to submersible motor  28  via a suitable internal conductor or conductors, e.g. three internal wire conductors, to provide power thereto. The docking assembly further comprises a receiving tubular  62  which is coupled to the docking station  60  and sized to receive the submersible pumping system  20 , e.g. electric submersible pumping system  24 . The receiving tubular  62  may comprise a single tubular or a plurality of aligned tubulars having internal diameters sufficiently large to receive the electric submersible pumping system  24  as the motor connector  54  is moved down into electrical engagement with the docking station  60  (see  FIG. 6 ). 
     Electric power is provided to docking station  60  via an electrical power cable  64 . Electrical power cable  64  may be routed from a surface power source or other suitable power source and deployed downhole with or as part of docking assembly  58 . In the illustrated example, the power cable  64  is routed down along the exterior of receiving tubular  62  and into docking station  60 . A cable clamp or clamps  66  may be used to secure the power cable  64  along receiving tubular  62 . 
     In some embodiments, the docking assembly  58  may comprise other components, such as a docking station seal assembly  68  constructed to seal against a surrounding surface, e.g. against casing  42 . In some applications, the seal assembly  68  may be in the form of a packer selectively expandable against the surrounding casing  42 . In the illustrated example, the docking station seal assembly  68  is connected to receiving tubular  62 . 
     The docking assembly  58  also may comprise other components, such as a valve  70  coupled between a fluid intake  72  and the docking station  60 . Fluid intake  72  allows fluid from the borehole  36  to enter into the interior of docking assembly  58  for pumping by, for example, the electric submersible pumping system  24  located inside. The valve  70  may be provided to enable selective closure of this flow path into docking assembly  58 . In some embodiments, valve  70  may be controlled via a control line  74 , e.g. a hydraulic control line, pneumatic control line or electrical control, selected according to the valve type. 
     With additional reference to  FIG. 3 , an embodiment of the electric submersible pumping system  24  is further illustrated. The electric submersible pumping system  24  is sized for receipt in docking assembly  58  and comprises submersible pump  26 , submersible motor  28 , motor protector  30 , and motor connector  54  as illustrated in  FIG. 1 . The motor connector  54  comprises at least one electrical connector  76 , e.g. a plurality of electrical connectors  76 , positioned for engagement with at least one corresponding electrical wet connector, e.g. a plurality of corresponding electrical wet connectors, in docking station  60 . In some embodiments, submersible motor  28  is powered by three-phase electrical power and three electrical connectors  76  are conductively coupled with motor  28  via suitable internal conductors for supplying the three-phase power to submersible motor  28 . The motor connector  54  may be positioned at a lower end of the electric submersible pumping system  24  to facilitate engagement with docking station  60 . Once the motor connector  54  is electrically engaged with docking station  60 , electrical power can be provided to submersible motor  28  via electricity supplied to docking station  60  by power cable  64 . 
     Depending on the application, the electric submersible pumping system  24  may comprise other components, such as a pumping system seal assembly  78 . The pumping system seal assembly  78  is positioned for sealing engagement with the interior of receiving tubular  62  when the electric submersible pumping system  24  is deployed down into docking assembly  58 . The electric submersible pumping system  24  may comprise other components, such as gauge section  32  having sensors  80 . The electric submersible pumping system  24  also may comprise other features such as expansion joint  34 , a swivel  82 , a bypass valve  84 , and/or other components to facilitate a given operation. The swivel  82  may be used for aiding alignment of motor connector  54  with docking station  60  without turning the entire electric submersible pumping system  24  or the entire well string. The swivel  82  may be located at a variety of locations along the electric submersible pumping system  24 . For example, the swivel  82  may be located immediately above motor connector  54  so that the motor connector  54  is able to rotate without rotating the entire electric submersible pumping system  24 . 
     Referring generally to  FIG. 4 , a view of an interior  86  of docking station  60  is provided. In this example of docking station  60 , the interior  86  is sized and shaped to receive motor connector  54  (see  FIG. 5 ). Within interior  86 , the docking station  60  comprises at least one electrical wet connector  88 , e.g. a plurality of electrical wet connectors  88 . In some applications, three electrical wet connectors  88  are provided to enable supply of three-phase power for submersible motor  28 . The electrical wet connectors  88  may be positioned to receive the corresponding electrical connectors  76  of motor connector  54  in, for example, a male-female engagement. It should be noted various types of structures may be used for the electrical wet connector(s)  88 . In some embodiments, a single wet connector structure  88  may include a plurality of conductors, e.g. three conductors for providing three-phase power. In other embodiments, an individual electrical wet connector  88  may be used for each conductor. 
     The docking station  60  also comprises a fluid flow passage  90 , e.g. a throughbore. Fluid entering through intake  72  is able to pass through fluid flow passage  90  and into interior  86  of the docking station  60 . As fluid fills the interior of the docking assembly  58 , the electric submersible pump  24  may be operated to pump the fluid to a desired location. To facilitate space efficiency and engagement of the motor connector  54  with docking station  60 , the fluid flow passage  90  and wet connector(s)  88  may be eccentrically positioned with respect to a central longitudinal axis  91  of the docking station  60 . In other words, the fluid flow passage  90  is radially offset from the central longitudinal axis  91  and the wet connectors  88  are not equally spaced along an entire circle concentric with the central longitudinal axis  91 . The fluid flow passage  90  and the wet connector(s)  88  may be located in various off-axis positions. By way of example, the fluid flow passage  90  and the wet connector(s)  88  may be completely or substantially in opposed semicircular regions of a cross-section taken through the central longitudinal axis  91  of the docking station  60 . In some embodiments, wet connectors  88  may be equally spaced from each other while being eccentrically positioned with respect to the central longitudinal axis  91 . The corresponding fluid flow passage  90  and electrical connectors  76  of motor connector  54  may be comparably arranged to facilitate engagement. 
     In some applications, the docking station  60  also may comprise orientation features  92 , e.g. an edge or fin, positioned to rotationally secure the motor connector  54 . For example, the orientation features  92  may be positioned to engage corresponding orientation features  94  (see  FIG. 5 ) on motor connector  54 . In some applications, the orientation features  92 ,  94  may be used alone or in cooperation with other features to rotate the motor connector  54  and overall electric submersible pumping system  24  for proper alignment of electrical connectors  76  with the corresponding electrical wet connectors  88 . As described in greater detail below, the rotational alignment may occur as the motor connector  54  is inserted into electrical engagement with docking station  60 , as illustrated in  FIG. 6 . The electric submersible pumping system  24  may be secured and sealed within receiving tubular  62  via pumping system seal assembly  78 . The use of orientation features  92 ,  94  also facilitates the off-axis positioning of fluid flow passage  90 , wet connectors  88 , and electrical connectors  76  by ensuring proper alignment of electrical connectors  76  and wet connectors  88  during engagement of motor connector  54  with docking station  60 . 
     Referring generally to  FIG. 7 , a schematic illustration is provided of an embodiment of a connection between power cable  64  and one of the electrical wet connectors  88  disposed in docking station  60 . In this example, the power cable  64  is routed along the exterior of the docking station  60  to a coupling section  96  of the docking station  96 , e.g. a junction box. In some embodiments, the power cable  64  may be disposed inside of a channel formed along the exterior of docking assembly  58  to shield the power cable  64  from physical impact during insertion into the borehole  36 . 
     Within the coupling section/junction box  96 , individual conductors  98  of power cable  64  may be independently coupled with corresponding electrical wet connectors  88 , as further illustrated in  FIG. 8 . In some embodiments, the power cable  64  comprises three conductors  98  for three-phase power. However, other embodiments may use a single conductor  98  or other numbers of conductors  98 . In the illustrated embodiment, the three individual conductors  98  may be separated from each other within junction box  96  and placed in electrical communication with corresponding electrical wet connectors  88 . In some embodiments, the junction box  96  may be part of docking station  60 , e.g. located along or within docking station  60 . Additionally, the junction box  96  may have a seal which effectively seals about power cable  64  so as to prevent unwanted entry of well fluids into sealed junction box  96 . 
     According to the embodiment illustrated in  FIG. 8 , power cable  64  enters junction box  96  and the conductors  98 , e.g. three conductors, of the power cable  64  are split into individual conductors and coupled with corresponding individual electrical wet connectors  88 . By way of example, the individual conductors  98  of power cable  64  may be separated within junction box  96  and routed through corresponding conduits  100 . The conduits  100  extend from the junction box  96  and along the interior of docking station  60  to shield the individual conductors  98  from, for example, well fluid. In this example, the individual conductors  98  are routed through conduits  100  and are electrically connected to the corresponding electrical wet connectors  88 , as illustrated. 
     Referring generally to  FIG. 9 , an embodiment of motor connector  54  is illustrated. In this embodiment, the motor connector  54  comprises electrical connectors  76 , e.g. male electrical connectors. The motor connector  54  also may comprise a fluid passage  102  which receives fluid flow from fluid flow passage  90  and directs the fluid out through at least one discharge port  104 . The fluid flows from the discharge port(s)  104  and then along the interior of docking assembly  58  to intake  56  of submersible pump  26 . 
     In the illustrated example, motor connector  54  further comprises orientation feature  94  which may be in the form of a detent for receiving corresponding orientation feature  92 , e.g. an orientation tab, when the motor protector  54  is inserted into docking station  60 . In some embodiments, motor connector  54  also may comprise a further orientation feature  106  which may be in the form of an orientation fin. For example, the orientation fin  106  may have a generally triangular shape or a generally arched shape. In some embodiments, the orientation fin  106  may have the shape of a tube which has been cut in half lengthwise and whose length has been cut at a non-oblique angle so as to form a single lead point and two surfaces which curve away from the lead point towards the remainder of the motor connector  54 . In some embodiments, the orientation fin  106  may be in the form of a hollow semi-cylindrical body having a pointed tip. These are just a few examples of orientation features  106  which may be used in cooperation with docking assembly  58  to rotate the motor connector  54  and overall electric submersible pumping system  24  to the desired rotational position for engagement of electrical connectors  76  with corresponding electrical wet connectors  88 . 
     Referring generally to  FIG. 10 , an embodiment of the docking station  60  is illustrated to show interior region  86 . In this example, orientation feature  92  may comprise at least one orientation tab  108  positioned for receipt in orientation feature/detent  94  of motor connector  54 . Additionally, the docking station  60  may comprise other internal orientation features, such as an orienting track  110  and an orienting edge  112 . By way of example, the orienting track  110  may be positioned to interact with orientation fin  106  of motor connector  54  to rotate the motor connector  54  about its axis during insertion of motor connector  54  into interior region  86 . The interaction of orientation fin  106  and orienting track  110  positions electrical connectors  76  for linear engagement with corresponding electrical wet connectors  88 . 
     In some embodiments, the orienting track  110  may have a generally elliptical shape disposed at a non-oblique angle relative to a longitudinal axis of the docking station  60 . For example, the orienting track  110  may extend along an elliptical or otherwise curvilinear path about a portion of the interior circumference of the docking station  60 . In some embodiments, the orienting track  110  may be used in cooperation with the orienting edge  112 . The orienting edge  112  also may be positioned for interaction with orienting fin  106  to, for example, rotate and then hold the motor connector  54  at the desired angular position during insertion of the motor connector  54  into the corresponding docking station  60 . This allows the electrical connectors  76  to be linearly inserted into corresponding electrical wet connectors  88 . As with the embodiment described above with reference to  FIGS. 4-6 , the fluid flow passages  90 ,  102  as well as the electrical connectors  76  and corresponding electrical wet connectors  88  may be located at off-axis positions, e.g. eccentric positions. The orientation features  92 ,  94  enable proper alignment and engagement of the electrical connectors  76  and corresponding electrical wet connectors  88  even when located at the eccentric positions. 
     Referring generally to  FIG. 11 , an embodiment is illustrated in which a centralizer or centralizers  114  are used to centralize the motor connector  54  during insertion into docking assembly  58 . According to an embodiment, the interior of docking assembly  58  may include a plurality of centralizers  114  positioned to interact with motor connector  54  to centrally position the motor connector  54  within the docking assembly  58 . In some embodiments, the centralizers  114  may be constructed and positioned to induce rotation of the motor connector  54  about its longitudinal axis to facilitate rotational alignment of the electrical connectors  76  with the corresponding electrical wet connectors  88 . 
     In some embodiments, an upper portion  116  of each centralizer  114  extends gradually inward from an interior surface  118  of the docking assembly  58 , e.g. from the interior surface of the docking station  60 . In this manner, the centralizers  114  are able to guide the motor connector  54  without providing an abrupt leading edge that could otherwise impede descent of the motor connector  54  into the docking station  60 . A main thickness  120  of each centralizer  114  may be sufficient to centralize the motor connector  54  within the interior region  86  of the docking station  60  and to aid in alignment of the motor connector  54  for proper connection between the electrical connectors  76  and the corresponding electrical wet connectors  88 . 
     According to an embodiment, at least one centralizer  114 , e.g. a plurality of centralizers  114 , may operate in conjunction with the orienting track  110  and/or orienting edge  112  to both centralize and orient the motor connector  54  with respect to the docking station  60 . According to an example, an uppermost edge of the orienting track  110  gradually extends from the interior surface  118  of docking station  60  without providing an abrupt edge that could otherwise impede the dissent of the motor connector  54  into the docking station  60 . The centralizers  114  may be constructed in a variety of shapes, including hexagonal shapes, triangular shapes, reuleaux triangular shapes, or other suitable shapes. 
     The docking assembly  58  may be used with a variety of submersible pumping systems  20  to make electrical power available without routing a dedicated power cable with the submersible pumping system. The components of docking assembly  58  may be selected according to the parameters of a given operation and/or environment. For example, various types of electrical wet connectors, junction boxes, tubular structures, orientation features, and/or other components may be selected to properly position and engage the submersible pumping system while providing electrical power thereto. Similarly, the submersible pumping system  20  may utilize various types of motor connectors and corresponding electrical connectors for engagement with the docking station  60  of the overall docking assembly  58 . Similarly, various types of power cables including at least one individual conductor, e.g. three individual conductors, may be used to provide power to the docking station  60 . 
     Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.