Patent Publication Number: US-11643911-B2

Title: Integrated electric submersible pumping system with electromagnetically driven impeller

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present document is based on and claims priority to U.S. Provisional Application Ser. No. 62/366,907, filed Jul. 26, 2016, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Following discovery of a desired subterranean resource, e.g. oil, natural gas, or other desired subterranean resources, well drilling and production systems often are employed to access and extract the resource or resources. For example, a wellbore may be drilled into a hydrocarbon bearing reservoir and then a pumping system may be deployed downhole. The pumping system is operated to pump oil and/or other fluids to the surface for collection when the natural drive energy of the reservoir is not strong enough to lift the well fluids to the surface. The pumping system may comprise an electric submersible pumping system having a submersible centrifugal pump powered by a separate submersible electric motor. 
     SUMMARY 
     In general, the present disclosure provides a system and methodology for pumping fluids. According to an embodiment, an electric submersible pumping system is constructed with an outer housing which contains an integrated pump and motor. For example, the pump may comprise an impeller disposed within a stator of the motor. The integration of the pump and the motor enables elimination of various components of traditional electric submersible pumping systems to thus provide a simpler and more compact system for pumping fluids. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments 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 various implementations described herein and are not meant to limit the scope of various technologies described herein, and: 
         FIG.  1    is a schematic illustration of an example of a well system including an electric submersible pumping (ESP) system, according to an embodiment of the disclosure; 
         FIG.  2    is a cross-sectional illustration of an example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  3    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  4    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  5    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  6    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  7    is a cross-sectional illustration taken through an axis of an embodiment of the integrated pump and motor to illustrate magnetic lines, according to an embodiment of the disclosure; 
         FIG.  8    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  9    is a cross-sectional illustration of another example of an integrated pump and motor of the ESP system, according to an embodiment of the disclosure; 
         FIG.  10    is a cross-sectional illustration taken through an axis of another embodiment of the integrated pump and motor to illustrate magnetic lines, according to an embodiment of the disclosure; and 
         FIG.  11    is a cross-sectional illustration taken through an axis of another embodiment of the integrated pump and motor to illustrate magnetic lines, according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of some illustrative 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 disclosure herein generally relates to a system and methodology for pumping fluids, e.g. well fluids. According to an embodiment, an electric submersible pumping system is constructed for deployment in a borehole or other suitable location to pump desired fluids. The electric submersible pumping system may be constructed with an outer housing containing an integrated pump and motor. For example, the pump may comprise an impeller disposed within a stator of the motor. The integration of the pump and the motor enables elimination of various components of traditional electric submersible pumping systems to thus provide a simpler and more compact system for pumping fluids. 
     According to an embodiment of the integrated pump and motor, the stator is disposed within the outer housing and comprises a stack of stator laminations having a bore extending longitudinally through the stack. The stator further comprises a plurality of slots disposed around the bore combined with magnet wire disposed within the slots. An impeller is disposed within the stator and comprises an impeller body, a magnetic component about the impeller body, and a permanent magnet. By way of example, the permanent magnet may be mounted about the magnetic component. In this embodiment, the impeller is positioned within the bore extending through the stack of stator laminations to provide the integrated pump and motor. In various embodiments, the integrated pump and motor comprises a stack of impellers and corresponding diffusers located within the stator. 
     For well applications, the electric submersible pumping system may be used for lifting well fluids to, for example, a surface location. Embodiments of the electric submersible pumping system integrate an electrical motor with a pump to provide a simple pumping system of convenient size. In some embodiments, the electrical motor may be constructed with a stator having a magnetic core and a winding sealed from the ambient environment or made of materials which are not susceptible to the ambient environment. In various embodiments, centrifugal pump stages may be installed within an inside diameter of the stator. 
     By way of example, the centrifugal pump stages may comprise stationary diffusers which may be fixed to the stator, e.g. fixed within the inner diameter of the stator. In some embodiments, the stationary diffusers may be positioned within the stator and fixed along a stationary shaft. The impellers may be equipped with components that generate torque while being exposed to a rotating magnetic field resulting by applying electric power to the stator. Examples of components that generate torque include permanent magnets, squirrel cage rotors, switched reluctance or synchronous reluctance rotors, or other suitable torque generating components. In some embodiments, the impellers may be installed on a rotating shaft in packs and the packs may be radially stabilized by radial fluid film bearings installed in corresponding, stationary diffusers. 
     The stator may be constructed with multi-phase winding and may be fed with AC voltage to generate a rotational magnetic field within the stator inner diameter. The rotating magnetic field interacts with the torque generating components of the impellers, thus causing the impellers to rotate and to thus pump fluid through the integrated pump and motor. 
     Referring generally to  FIG.  1   , an embodiment of an electric submersible pumping system  20  is illustrated as deployed downhole into a borehole  22 , e.g. a wellbore, for production of desired fluids, e.g. oil. Electric submersible pumping system  20  may comprise a variety of components depending on the particular application or environment in which it is used. By way of example, the electric submersible pumping system  20  may comprise a pumping section  24  having an outer housing  26  containing an integrated pump and motor  28 . The integrated pump and motor  28  effectively combines a pump  30  and a motor  32  within the outer housing  26  to provide a simple, compact structure for pumping fluids, e.g. well fluids. The pump  30  of integrated pump and motor  28  may comprise floater stages, compression stages, or modular compression with impeller flow passages oriented to provide radial flow, mixed flow, axial flow, or other desired flow patterns through the integrated pump and motor  28 . 
     In the embodiment illustrated, the borehole  22  is in the form of a wellbore drilled into a geological formation  34  which contains a desirable fluid  36 , e.g. a production fluid such as oil. The borehole  22  may be lined with a tubular casing  38  and perforations  40  may be formed through casing  38  to enable flow of fluids between the surrounding formation  34  and the borehole/wellbore  22 . The electric submersible pumping system  20  may be deployed down into borehole  22  via a conveyance system  42 . By way of example, the conveyance system  42  may comprise tubing  44  (e.g. coiled tubing, production tubing) or cable coupled with pumping section  24  via a connector  46 . 
     Electric power may be provided to the motor  32  of pumping section  24  via a power cable  48 . This allows the motor  32  to power pump  30 , as described in greater detail below, so as to draw in fluid  36  through a suitable pump intake  50 . The pump  30  may comprise an impeller or impellers which are rotated by an electromagnetic interaction with a rotating magnetic field generated by motor  32  to produce the fluid  36  through the integrated pump and motor  28 . In well applications, the fluid  36  may be produced up through tubing  44  (or along an annulus surrounding tubing  44 ) to a desired collection location which may be at a surface  52  of the earth. 
     According to an embodiment, the pump  30  may be a multi-stage centrifugal pump. Each stage may comprise an impeller working in cooperation with a stationary diffuser. The impellers are driven by the magnetic field of the motor  32  such that vanes of the rotating impellers convert the driver/motor energy to kinetic energy which is applied to the fluid. The fluid is thus thrown outward by the impeller vanes in a direction away from the center of the impeller. The fluid discharged from the impeller may first contact the inner wall of the adjacent, cooperating diffuser. In some embodiments, the impeller may be rotatably mounted within the cooperating diffuser. The cooperating diffusers direct the flowing fluid from one impeller to the next until the flowing fluid is discharged from the pumping section  24 . In some downhole centrifugal pumping systems, the number of pump stages may be determined by the total dynamic head (TDH), stage type performance characteristics, and desired flow rate. For deep wells where high TDH is desired, the overall pumping system may comprise a plurality of the pumping sections  24  connected in tandem hydraulically and electrically. 
     In embodiments of the disclosure, a motor stator and hydraulic centrifugal pump are combined in a single assembly. The stator may be represented by a laminated magnetic core with multi-phase winding distributed in slots. The winding may be fed by multi-phase AC voltage creating a rotating magnetic field over the space within the stator inner diameter (ID). The stator ID may be sealed from the ambient environment by a corrosion and erosion resistant material of cylindrical shape (e.g. a “can”). In some embodiments of the disclosure, the stator may be constructed from materials resistant to the ambient environment or from a stack of lamination packs individually sealed from the ambient environment by isolating material, e.g. plastic. According to an arrangement, magnetic lamination packs may alternate with non-magnetic packs located adjacent to non-torque producing components of the pump, e.g. diffusers, to reduce power loss in the magnetic core of the stator. 
     According to an embodiment, non-magnetic stationary diffusers may be installed inside the stator ID. The non-magnetic diffusers may be fixed at desired positions within the stator. For example, the non-magnetic diffusers may be fixed tangentially by, for example, engagement of locking keys with corresponding key grooves located along the stator ID. In some applications, the stack of diffusers may be compressed from the ends of the stack. Furthermore, some embodiments may lock the non-magnetic diffusers along a stationary shaft via keys or other locking mechanisms. In some embodiments, each diffuser may have a two-piece construction in which one part has vanes made of magnetic material and the other part, adjacent to the torque producing impeller, is made of a non-magnetic material, e.g. ceramic or other erosion and corrosion resistant material. 
     Each impeller installed inside the stator ID may be constructed of magnetic or non-magnetic material. Torque generating components or subassemblies such as permanent magnets, squirrel cage rotors, switched reluctance or synchronous reluctance rotors, or other torque generating components may be fixed on the impeller or formed as integral parts of the impeller. For example, permanent magnets or other torque generating components may be fixed in the front seal area (front skirt) or in the balance ring area of each impeller. The torque generating components are positioned to interact with the rotating magnetic field of the stator and to generate torque for driving the impellers. Rotating impellers and stationary diffusors are able to transform rotational kinetic energy into the hydrodynamic energy of the fluid flow. 
     In some embodiments of the disclosure, the entire impeller or the vanes of the impeller may be made of a magnetic material. By way of example, the entire impeller or portions of the impeller may be constructed from magnetic steel or other suitable magnetic material. The magnetic impeller is thus able to interact electromagnetically with a rotating magnetic field of the stator such that the impeller functions simultaneously as the impeller of centrifugal pump and the rotor of the motor. 
     Each impeller may have its own axial and radial support in the form of a bearing made of wear resistant material, e.g., a ceramic or carbide material. The plurality of impellers may be assembled collectively or in separate packs. Additionally, the entire group of impellers or packs of the impellers may be assembled in a floater configuration or in compression. In some applications, the impellers may be rotated about or with a corresponding central shaft. At least some of these configurations may allow for increases in rotating torque within pump stages to prevent the pump from getting stuck due to abrasives. 
     Embodiments of the disclosure allow for the elimination of traditional ESP components such as the motor protector, intake, separate pump and motor sections, shafts, couplings, and the motor lead extension. Embodiments of the disclosure also may allow for the overall system efficiency to remain at, or be higher than, the level of conventional ESP system efficiency due to the use of high efficiency electrical machine design with high-efficiency hydraulic pump design without compromising either electromagnetic or hydraulic design. Shaft-less design configurations may allow for pump stages with the head of, and higher efficiency than, a conventional centrifugal pump stage due to an increased working area. Pump and motor integration into a single section may reduce the number of parts and shorten the total length of the ESP. A reduction in the number of sections also may minimize installation time at the wellsite and reduce the probability of failure caused by human error, thus increasing reliability. Elimination of torque transmission components such as shafts and couplings may allow flexible connections between integrated pumping sections which, in turn, can facilitate use of the electric submersible pumping system  20  in wells having high dogleg severity. 
     Referring generally to  FIG.  2   , an embodiment of at least a portion of electric submersible pumping system  20  is illustrated. In this example, the pumping section  24  comprises integrated pump and motor  28  disposed within outer housing  26 . The integrated pump and motor  28  comprises pump  30  which may be in the form of a centrifugal pump having at least one impeller  54  and at least one diffuser  56 . In these types of embodiments, the at least one impeller  54  may comprise various styles of impeller vanes for moving fluid upon impeller rotation. However, pump  30  and impeller  54  may be constructed in various other types of configurations. In the illustrated embodiment, the pump  30  comprises a plurality of impellers  54  positioned in cooperation with corresponding diffusers  56 . As described in greater detail below, the impellers  54  may be magnetic impellers and the diffusers  56  may be non-magnetic diffusers. 
     During operation, the plurality of impellers  54  receives fluid, e.g. well fluid through an intake  58  (which receives fluid from system pump intake  50 ) and directs the fluid to the next sequential diffuser  56  which, in turn, directs the fluid to the next sequential impeller  54 . The fluid flows along a flow path  60  through sequential impellers  54  and diffusers  56  until being discharged through a discharge head  62 . The flow path  60  may be in the form of a fluid conduit for transporting fluid from a first side to a second side of each impeller  54  and from a first side to a second side of each diffuser  56  sequentially. In this example, each impeller  54  further comprises a magnetic component  64  which may be disposed at various positions within the impeller  54  or along the exterior of impeller  54 . By way of example, each magnetic component  64  may be annular in shape and have the form of a ring or cylinder disposed about a body  66  of the impeller  54 . 
     As illustrated, each impeller  54  also may comprise a magnet  68 , e.g. a permanent magnet, positioned at an external location with respect to the impeller body  66 . By way of example, each magnet  68  may be annular in shape and in the form of a ring or cylinder positioned around the corresponding magnetic component  64 . 
     Functionally, the magnetic component  64  and magnet  68  may be considered part of the motor  32 . Because the magnetic components  64  and magnets  68  of impellers  54  are fixed to the impeller bodies  66 , motor  32  is able to rotate the impellers  54  so as to pump fluid from intake  58  and out through discharge head  62 . It should be noted the magnetic component  64  and magnet  68  may be combined with the corresponding impeller body  66  on an individual impeller  54  or on groups of impellers  54  selected from the overall group of impellers  54 . 
     In this example, the motor  32  comprises a stator  70  disposed along the interior of outer housing  26 . The stator  70  may be annular in form and have a central passage  71 , e.g. a bore, therethrough. The stator  70  may be constructed with a magnetic core and/or with materials having desired magnetic or electric anisotropy. In some embodiments, the stator  70  is constructed with a plurality of stacked stator laminations  72 . A magnet wire  74  (or magnet wires) may extend through the stator  70  in a generally lengthwise direction. By way of example, magnet wire passages, e.g. slots, may be formed longitudinally through the stator  70 , e.g. through the stack of stator laminations  72 , and the magnet wire  74  may be fed through the magnet wire passages to form a stator coil. Longitudinal ends of the magnet wire may be contained by coil end encapsulations  76 , e.g. by a coil end encapsulation  76  located at each end of the stacked stator laminations  72 . 
     The non-magnetic diffusers  56  may be held in stationary positions with respect to stator  70 . By way of example, each diffuser  56  may be locked to the surrounding stator  70  via a key or other protuberance  78  of each diffuser  56  engaging a corresponding recess  80  located along an inside diameter of the stator  70 . Consequently, the non-magnetic diffusers  56  are prevented from rotating during rotation of impellers  54  while operating the integrated pump and motor  28 . 
     To cause operation of motor  32  and pumping of fluid via pump  30 , electricity is supplied to magnet wire  74  via an electric cable  82  coupled with magnet wire  74  via a cable connector  84 . Electric cable  82  may be the same as or part of overall power cable  48 . The rotating magnetic field created by electricity flowing along the winding created by coiled magnet wire  74  extends to the inside diameter of stator  70  and interacts with magnetic impellers  54 , e.g. with magnetic components  64  and corresponding magnets  68 . For example, the magnets  68  may be oriented to provide appropriately positioned polarity along the outer surface of the impellers  54 . In this manner, the stator  70 , magnetic components  64 , and corresponding magnets  68  function as an electric motor and cause rotation of the impellers  54 . The structure of impellers  54  enables the impellers  54  to function as a rotor of the motor  32  while also facilitating pumping of fluid along pump  30 . According to at least some embodiments described herein, the magnetic gap between the stator  70  and the magnets  68  is constant and continuous. In the example illustrated in  FIG.  2   , the impellers  54  may rotate independently with respect to each other. 
     Referring generally to  FIG.  3   , another embodiment of pumping section  24  is illustrated. In this example, the integrated pump and motor  28  comprises a stationary shaft  86  extending generally along a central axis of the pumping section  24 . The shaft  86  is fixed in a stationary position within housing  26  via shaft fixators  88  coupled between, for example, the shaft  86  and housing  26  (or between the shaft  86  and stator  70 ). In this example, the stationary, non-magnetic diffusers  56  are locked to stationary shaft  86 . However, the impellers  54  may freely rotate about the shaft  86 . In some embodiments, the impellers  54  may rotate about shaft  86  independently with respect to each other or in desired groups. 
     In this embodiment, stator  70  may again comprise a winding of magnet wire  74  which is supplied with electricity via electric cable  82 . The resulting magnetic field is used to rotate impellers  54  which cause the inflow of fluid through intake  58  and the discharge of fluid through discharge head  62 . The flowing fluid, e.g. well fluid, passes through the plurality of non-magnetic diffusers  56  and magnetic impellers  54  before being discharged through discharge head  62 . 
     Referring generally to  FIG.  4   , another embodiment of pumping section  24  is illustrated. In this example, the non-magnetic diffusers  56  include flanges  90  which extend to an inside surface of outer housing  26 . The flanges  90  extend through stator  70  and interrupt the continuity of the stator laminations  72 . The magnet wire  74  extends through both the stator laminations  72  and the flanges  90  to provide a suitable winding for enabling rotation of impellers  54  when electric power is supplied via electric cable  82  and a rotating magnetic field is established via stator  70 . In this embodiment, the diffusers  56  and the stator laminations  72  may be compressed together to provide higher down-thrust capability of the stages. It should be noted stages, as used herein, means adjacent pairings of impeller  54  and diffuser  56 . Depending on the pumping capacity desired, different numbers of stages (pairs of impellers  54  and diffusers  56 ) may be assembled to form the integrated pump and motor  28 . The embodiment illustrated in  FIG.  4    also may help reduce core loss which otherwise may result from unused stator laminations where there is no corresponding rotor magnet zone. 
     Referring generally to  FIG.  5   , another embodiment of pumping section  24  is illustrated. In this example, the non-magnetic diffusers  56  are again locked in a stationary position with respect to stator  70  by, for example, protuberances  78  and corresponding recesses  80 . However, a shaft  92 , e.g. a rotatable shaft, is disposed through magnetic impellers  54  and non-magnetic diffusers  56 . The shaft  92  may be supported by at least one shaft thrust bearing  94 . For example, the shaft  92  may be supported on both ends by corresponding thrust bearings  94 . In this embodiment, the magnetic impellers  54  may be rotationally constrained on shaft  92  by, for example, keys and a corresponding keyway or other suitable locking mechanisms. By locking the magnetic impellers  54  on shaft  92 , the total load torque transmission is shared by each impeller/stage during torque generation, e.g. during operation of motor  32 . Thus, if a stage/impeller becomes stuck the accumulation of stage torque on the shaft  92  may aid in freeing the stuck stage/impeller. 
     Referring generally to  FIG.  6   , another embodiment of pumping section  24  is illustrated. In this example, a hollow shaft  96  is disposed through magnetic impellers  54  and non-magnetic diffusers  56 . The hollow shaft  96  comprises an internal passage  98  sized for receiving a tool  100  therethrough. By way of example, the tool  100  may be in the form of a wireline logging tool  102  coupled with a logging tool cable  104  and passed through hollow shaft  96  via passage  98 . The tool  100  may be deployed through the hollow shaft  96  to, for example, a position below the electric submersible pumping system  20 . 
     The hollow shaft  96  may be used with a variety of embodiments. For example, the shaft  86  or the shaft  92 , described above, may be constructed as hollow shaft  96 . In some embodiments, a valve  106  may be mounted at the top of pumping section  24  or at another suitable location. The valve  106  may be in the form of a check valve or other suitable valve which is closed to block passage  98  when the pumping system is activated. However, the valve  106  may be moved to an open position to allow tool  100  to be passed through the hollow shaft  96 . 
     In  FIG.  7   , a cross-sectional illustration of the integrated pump and motor  28 , taken perpendicularly through the axis of the integrated pump and motor  28 , is provided to show an example of an arrangement of magnetic lines  108 . In this example, the motor  28  comprises stator  70  and is arranged in the form of a 3-phase, 4-pole, 24-slot configuration. Additionally, the impellers  54  are each arranged to have magnet  68  in the form of a permanent magnet ring  110  and magnetic component  64  in the form of a magnetic steel hub  112 . Thus, each impeller  54  includes impeller body  66 , magnetic steel hub  112 , and permanent magnet ring  110 . The impellers  54  are disposed within the passage/bore  71  formed by the inner diameter of stator  70 . For example, the passage  71  may be formed along the interior of stator laminations  72  within outer housing  26 . 
     Referring generally to  FIG.  8   , another embodiment of pumping section  24  is illustrated. In this example, a pin  116  or a plurality of pins  116  may be used to connect sequential magnetic impellers  54 . By way of example, the pin(s)  116  may be located along an axis of the pumping section  24 . In this embodiment, the pin or pins  116  are constructed for providing radial and/or axial stability rather than for transferring torque as with certain types of shafts. As with other embodiments, the magnet wire  74  may extend through the stator laminations  72  to enable rotation of impellers  54  when electric power is supplied via electric cable  82 . 
     Depending on the parameters of a given application, the torque producing component, e.g. impeller  54 , may be constructed in a variety of forms. In embodiments described above, for example, a torque producing component or components may be created using an impeller body  66  combined with a magnetic component  64  and an annular permanent magnet  68 . However, the torque producing component, e.g. magnetic components of impeller  54 , may be constructed in various other configurations. Examples of such configurations include an induction cage, a reluctance rotor, or another suitable component able to generate torque when electricity is applied via cable  82 . 
     Referring generally to  FIG.  9   , another embodiment of pumping section  24  is illustrated. In this example, impellers  54  are constructed from a magnetic material which electromagnetically interacts with stator magnetic poles of stator  70 . As with other embodiments described herein, the impellers  54  are constructed to function as a rotor of motor  32  for interaction with the stator magnetic poles. Simultaneously, the impellers  54  function as conventional pump impellers of pump  30  so as to move fluid, e.g. well fluid, generally in an axial direction along flow channel  60 . 
     In  FIG.  10   , a cross-sectional illustration of the integrated pump and motor  28 , taken perpendicularly through the axis of the integrated pump and motor  28 , is provided to show another example of an arrangement of magnetic lines  108 . In this example, the impellers  54  each comprise impeller vanes  118  which are made of magnetic material. The magnetic material allows the impellers  54  to function as both a motor rotor and a pump impeller simultaneously. In this example, the impellers  54  are constructed such that the motor  32  operates as a reluctance motor. 
     In  FIG.  11   , a cross-sectional illustration of the integrated pump and motor  28 , taken perpendicularly through the axis of the integrated pump and motor  28 , is provided to show another example of an arrangement of magnetic lines  108 . In this example, the impellers  54  each comprise permanent magnets  120  embedded into impeller vanes  118  which again allows the impellers  54  to function as both a motor rotor and a pump impeller simultaneously. 
     With respect to embodiments described herein, torque generating components (e.g. combined impeller body  66 , magnetic components  64 , and permanent magnet  68 ) may or may not be constructed to provide hydrodynamic functions of pump stage components such as impeller vanes. For example, permanent magnets  68  of impellers  54  may be constructed in the form of impeller vanes  118 , may be mounted along the impeller vanes  118 , or may be mounted at other suitable locations of the impellers  54  that do not participate in fluid pumping. In some embodiments, the impellers  54  may be constructed from a magnetic steel and function as a rotor of a synchronous reluctance motor. In this type of embodiment, the impellers  54  again generate torque when being exposed to a rotating magnetic field of the stator  70 . 
     Various embodiments described herein enable the elimination of traditional ESP components such as motor protector (seal), traditional motor, traditional pump shafts, couplings, motor lead extensions, and/or other components. The integrated pump and motor  28  may be constructed to provide a combined section having a reduced number of component parts combined with a shortening of the overall length of the ESP system  20  relative to a traditional ESP system. However, multiple combined sections may be connected in tandem to provide sufficient head desired for a given pumping system. 
     Additionally, the integrated pump and motor  28  may be constructed with different types of fluid pumping structures, e.g. different types of impellers. For example, the fluid pumping structure  54  may be in the form of a helical rotor in a progressive cavity pump. In this type of embodiment, the helical rotor is equipped with a torque producing element, e.g. a permanent magnet element or a magnetic steel element, and surrounded by stator  70  with a winding of magnet wire  74  to produce a rotating magnetic field. 
     By eliminating certain traditional components, e.g. shafts, as described above, embodiments of ESP system  20  allow for the flexible connection of pumping section  24  with other components of a well string. This ability negates application restraints related to trajectory of the wellbore in three-dimensional space and facilitates use of the pumping system in wellbores with greater dogleg severity. A flexible connection between sections of the well string may be achieved by a variety of methods including use of materials which allow a certain level of deformation and flexibility, articulating joints which permit relative angular movement between connected sections, or other suitable flexible connections. 
     The various components of pumping system  20  may be constructed from a variety of materials. For example, the impeller body  66  may be constructed from steel, aluminum, plastic, ceramic, or other suitable materials for a given application. In some embodiments, the impellers  54  may be constructed with suitable types of magnetic material. For example, the impeller body  66  may be constructed from the same material as magnetic component  64 . The magnetic components  64  also may be formed from various magnetic materials, such as magnetic steel. Similarly, the stator  70  may be constructed in various configurations using laminations  72  or other suitable structures. The electric cable  82  may have various materials and configurations and may be coupled with magnet wire  74  via various types of connectors  84 , e.g. motor lead extensions. Additionally, the pumping section  24  may be combined with many other types of components in the overall pumping system. 
     Although a few embodiments of the system and methodology 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.