Patent Publication Number: US-2022236082-A1

Title: Rotation monitoring assembly for an artificial lift system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of U.S. Provisional Application Ser. No. 63/142,319, entitled “ROTATION MONITORING ASSEMBLY FOR AN ARTIFICIAL LIFT SYSTEM”, filed Jan. 27, 2021, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to a rotation monitoring assembly for an artificial lift system. 
     Wells are drilled into reservoirs to discover and produce oil. The oil within such a reservoir may be under sufficient pressure to drive the oil through the well to the surface. However, over time, the natural pressure of the oil may decline, and an artificial lift system may be used to extract the oil from the reservoir. The artificial lift system may include a pump disposed within the reservoir and a wellhead at the surface. A tubing string may be supported by the wellhead and may extend to the reservoir, and the pump may drive the oil from the reservoir to the wellhead via the tubing string. 
     The pump is driven by a series of polish rods that extend through the tubing string to the pump. The polish rods are lifted and lowered by a pump jack, which supports the polish rods. The repeated lifting and lowering movement of the polish rods causes the polish rods to wear at the point(s) of contact with the tubing string. Accordingly, certain artificial lift systems include a rod rotator to drive the polish rods to rotate within the tubing string, thereby distributing the wear around the circumference of the polish rods. As a result, the longevity of the polish rods may be increased. 
     However, if rotation of the polish rods is terminated during operation of the artificial lift system, polish rod wear at the point(s) of contact may increase. Accordingly, an operator may periodically perform a visual inspection of the polish rods to determine whether the polish rods are rotating effectively. If the polish rods are not rotating effectively, the operator may perform maintenance operations (e.g., on the rod rotator). Unfortunately, the process of visually inspecting the polish rods for each artificial lift system within a field may be excessively time-consuming. 
     BRIEF DESCRIPTION 
     In certain embodiments, a rotation monitoring assembly for an artificial lift system includes a sensor having a body configured to couple to one of a non-rotating component of a polish rod connection assembly or a rotating component of the polish rod connection assembly. The rotation monitoring assembly also includes a target configured to couple to the other of the non-rotating component of the polish rod connection assembly or the rotating component of the polish rod connection assembly. A property of the target varies substantially continuously along a circumferential extent of the target, and the sensor is configured to output a sensor signal indicative of the property of the target. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a schematic side view of an embodiment of an artificial lift system having an embodiment of a rotation monitoring assembly; 
         FIG. 2  is a schematic side view of a portion of the artificial lift system of  FIG. 1 , including a wellhead and a polish rod connection assembly; 
         FIG. 3  is a schematic perspective view of the polish rod connection assembly of  FIG. 2 , in which the polish rod connection assembly includes the rotation monitoring assembly; 
         FIG. 4  is a schematic perspective view of a mounting assembly of the rotation monitoring assembly of  FIG. 3 ; and 
         FIG. 5  is a perspective view of a rod rotator assembly of the polish rod connection assembly of  FIG. 2 , in which a portion of the rod rotator assembly is cut away, and an embodiment of a rotation monitoring assembly. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. 
       FIG. 1  is a schematic side view of an embodiment of an artificial lift system  10  having an embodiment of a rotation monitoring assembly  12 . As illustrated, the artificial lift system  10  includes a pump  14  disposed within a reservoir  16 . The artificial lift system  10  also includes a wellhead  18  at the surface  20 . A tubing string  22 , which is supported by the wellhead  18 , extends from the surface  20  to the reservoir  16 . The pump  14  is configured to drive oil from the reservoir  16  to the surface  20  via the tubing string  22  and the wellhead  18 . 
     The pump  14  is driven by a series of polish rods that extend through the tubing string  22  to the pump  14 . As illustrated, a polish rod  24  at the end of the series of polish rods is coupled to a pump jack  26  of the artificial lift system  10 . The pump jack  26  is configured to lift and lower the polish rods, thereby driving the pump  14 . One or more polish rods may contact the tubing string  22  at one or more points along a circumference of the polish rod(s). Accordingly, as the polish rods are driven to move within the tubing string  22 , certain point(s) on the polish rod(s) may wear. In the illustrated embodiment, a rod rotator assembly  28  is configured to drive the polish rods to rotate within the tubing string  22 , thereby distributing the wear around the circumference of the polish rod(s). As a result, the longevity of the polish rods may be increased. As discussed in detail below, the rod rotator assembly  28  is supported by a carrier (e.g., carrier bar) that is supported by the pump jack  26  via one or more cables. 
     In certain embodiments, the rod rotator assembly  28  includes a housing supported by the carrier of the artificial lift system  10 . In addition, the rod rotator assembly  28  includes a top cap configured to rotate relative to the housing, in which the top cap is configured to support the polish rods (e.g., via polish rod clamp(s)). Furthermore, in certain embodiments, the rotation monitoring assembly  12  is utilized to monitor the rotation of the polish rods, thereby facilitating identification of ineffective operation of the rod rotator assembly  28 . The rotation monitoring assembly  12  includes a sensor having a contact element and a body. The body of the sensor is coupled to the housing of the rod rotator assembly, and the sensor is configured to output a sensor signal indicative of a position of the contact element relative to the body. In addition, the rotation monitoring assembly  12  includes one or more targets coupled to a rotating portion of the rod rotator assembly  28 , such as the end cap. Each target includes a contact surface configured to engage the contact element of the sensor, and a longitudinal extent of the contact surface (e.g., property of the target) varies (e.g., substantially continuously) along a circumferential extent of the target. Due to the variation in the longitudinal extent of the contact surface along the circumferential extent of the target, the contact surface may drive the contact element of the sensor to move relative to the sensor body as the rotating portion of the rod rotator assembly (e.g., the top cap) rotates relative to the rod rotator assembly housing. Accordingly, the sensor signal indicative of the position of the contact element relative to the body, which is based on the longitudinal extent of the contact surface (e.g., the property of the target), may vary as the rotating portion of the rod rotator assembly rotates. The sensor signal may be monitored (e.g., by a controller having a memory and a processor) to identify whether the polish rods are not rotating or are not rotating at a target rate, thereby enabling an operator to perform maintenance operations on the artificial lift system (e.g., on the rod rotator assembly). 
       FIG. 2  is a schematic side view of a portion of the artificial lift system  10  of  FIG. 1 , including the wellhead  18  and a polish rod connection assembly  29 . In the illustrated embodiment, the wellhead  18  includes a tubing spool  30  that supports the tubing string (e.g., via a tubing hanger coupled to an end of the tubing string and engaged with the tubing spool). The wellhead  18  also includes a pumping tee  32  coupled to the tubing spool  30  and to a flowline  34 . The pumping tee  32  is configured to receive oil from the tubing spool  30  and to control flow of the oil through the flowline  34 . The flowline  34  may extend to a storage or processing facility. Furthermore, the wellhead  18  includes a stuffing box  36  coupled to the pumping tee  32 . The stuffing box is configured to establish a seal around the polish rod  24  that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rod. While the wellhead  18  includes the tubing spool  30 , the pumping tee  32 , and the stuffing box  36  in the illustrated embodiment, the wellhead may include other and/or additional components in other embodiments. 
     As discussed in detail below, the polish rod connection assembly  29  includes the rod rotator assembly  28 , which is configured to drive the polish rods to rotate relative to the wellhead  18  and the tubing string. The polish rod connection assembly  29  also includes a carrier  38  (e.g., carrier bar) configured to support the rod rotator assembly  28 . The carrier  38  may be coupled to the pump jack by one or more cables. In addition, the polish rod connection assembly  29  includes one or more polish rod clamps  40  configured to non-movably couple to the polish rod  24 . The polish rod clamps  40  transfer the load (e.g., substantially vertical load) of the polish rods to the rod rotator assembly  28 , the load flows through the rod rotator assembly  28  to the carrier  38 , and the load applied to the carrier is transferred to the pump jack via the cable(s). Accordingly, during an upward movement of the pump jack, the pump jack lifts the carrier  38  via the cable(s), the carrier  38  drives the rod rotator assembly  28  to move upwardly, and the rod rotator assembly  28  drives the polish rods to move upwardly via engagement of the rod rotator assembly  28  with the polish rod clamp(s)  40 . During a downward movement of the pump jack, the pump jack drives the polish rod  24  downwardly. Because the polish rod clamp(s)  40  are non-movably coupled to the polish rod  24 , the polish rod clamp(s)  40  drive the rod rotator assembly  28  to move downwardly, thereby driving the carrier  38  to move downwardly. 
       FIG. 3  is a schematic perspective view of the polish rod connection assembly  29  of  FIG. 2 . As previously discussed, the polish rod connection assembly  29  includes the rotation monitoring assembly  12 , the rod rotator assembly  28 , the carrier  38 , and the polish rod clamps  40 . In the illustrated embodiment, the rod rotator assembly  28  includes a housing  42 , which is supported by the carrier  38 . The rod rotator assembly  28  also includes a top cap  44  configured to rotate relative to the housing  42 . As illustrated, the top cap  44  is engaged with the polish rod clamp(s)  40 , thereby supporting the polish rods. In addition, due to the engagement of the top cap  44  with the polish rod clamp(s)  40 , rotation of the top cap  44  relative to the housing  42  drives the polish rods to rotate, thereby increasing the longevity of the polish rods. While the polish rod connection assembly  29  includes two polish rod clamps  40  in the illustrated embodiment, in other embodiments, the polish rod connection assembly may include more or fewer polish rod clamps (e.g., 1, 3, 4, or more). 
     In the illustrated embodiment, the rod rotator assembly  28  includes a lever  46  configured to drive the top cap to rotate. The lever  46  may be coupled to a worm gear of the rod rotator assembly  28 , and movement of the lever may drive the worm gear to rotate. The worm gear may be engaged with a main gear of the rod rotator assembly  28  and configured to drive the main gear to rotate. The main gear, in turn, may be non-rotatably coupled to the top cap  44 . Accordingly, movement of the lever  46  may drive the top cap  44  to rotate, thereby driving the polish rods to rotate via contact between the top cap  44  and the polish rod clamp(s)  40 . The lever  46  may be driven to move via a cable extending between the lever  46  and a base of the pump jack. As the rod rotator assembly  28  moves upwardly and downwardly with the polish rods during operation of the pump jack, the cable cyclically drives the lever  46  to move in response to the rod rotator assembly  28  moving to a distance away from the pump jack cable anchor point that is greater than the length of the cable. While the top plate  44  is driven to rotate by the lever  46 , the worm gear, and the main gear in the embodiment disclosed herein, the top plate may be driven to rotate relative to the rod rotator assembly housing via any other suitable device/assembly (e.g., electric motor, pneumatic actuator, another suitable mechanical drive assembly, etc.). 
     In the illustrated embodiment, the rotation monitoring assembly  12  includes a sensor  48  having a contact element  50  and a body  52 . The body  52  of the sensor  48  is coupled to the housing  42  of the rod rotator assembly  28  (e.g., non-rotating component of the polish rod connection assembly  29 ), and the sensor  48  is configured to output a sensor signal indicative of a position of the contact element  50  relative to the body  52 . In certain embodiments, the sensor  48  includes a linear variable differential transformer (LVDT) having a core coupled to the contact element  50  and multiple coils extending around a central passage within the body  52 . In such embodiments, the sensor signal may correspond to a voltage output by the LVDT, and movement of the core within the central passage may vary the voltage output/sensor signal. Additionally or alternatively, the sensor  48  may include any other suitable type(s) of position monitoring device(s) (e.g., alone or in combination with one or more LVDTs), such as linear potentiometer(s), optical sensor(s), other suitable type(s) of position monitoring device(s), or a combination thereof. While the rotation monitoring assembly  12  includes a single sensor  48  in the illustrated embodiment, in other embodiments, the rotation monitoring assembly may include multiple sensors (e.g., distributed about a circumferential axis  60  of the rod rotator assembly  28 ). 
     In addition, the rotation monitoring assembly  12  includes a target  54  non-rotatably coupled to the top cap  44  (e.g., rotating component of the polish rod connection assembly  29 ), such that the target  54  rotates with the top cap  44 . The target  54  includes a contact surface  56  configured to engage the contact element  50  of the sensor  48 . In addition, a longitudinal extent of the contact surface  56  (e.g., extent of the contact surface along a longitudinal axis  58  of the rod rotator assembly  28 ), which is a property of the target, varies (e.g., substantially continuously) along a circumferential extent of the target  54  (e.g., extent of the target along the circumferential axis  60  of the rod rotator assembly  28 ). Due to the variation in the longitudinal extent of the contact surface  56  along the circumferential extent of the target  54 , the contact surface  56  may drive the contact element  50  of the sensor  48  to move relative to the sensor body  52  as the top cap  44  rotates relative to the rod rotator assembly housing  42 . Accordingly, the sensor signal indicative of the position of the contact element  50  relative to the body  52 , which is based on the longitudinal extent of the contact surface (e.g., property of the target), may vary as the top cap  44  rotates. The sensor signal may be monitored (e.g., by a controller having a memory and a processor) to identify whether the polish rods are not rotating or are not rotating at a target rate, thereby enabling an operator to perform maintenance operations on the artificial lift system (e.g., on the rod rotator assembly). In addition, because the longitudinal extent of the contact surface varies (e.g., substantially continuously) along the circumferential extent of the target, a non-rotating/improperly rotating polish rod may be identified rapidly, as compared to utilizing a rotation monitoring assembly that identifies presence of a rotating target at the location of a non-rotating sensor, which may only identify non-rotation/improper rotation of a polish rod after a substantial portion of a rotation of the top cap (e.g., which may only rotate once per 40-50 oscillations of the pump jack). 
     In certain embodiments, the contact element  50  is biased away from the body  52  (e.g., by a spring or other suitable biasing element). Accordingly, the contact element  50  of the sensor  48  is urged into contact with the contact surface  56  of the target  54 . Furthermore, in certain embodiments (e.g., in embodiments in which the target extends about the entire circumferential extent of the top cap), the contact element of the sensor may be coupled to the contact surface of the target. For example, the contact surface of the target may be formed on a rail or track that extends along the circumferential axis of the rod rotator assembly, and the contact element may include an engagement element (e.g., wheel, slider, etc.) engaged with the rail or track. 
     In the illustrated embodiment, the body  52  of the sensor  48  is coupled to the housing  42  of the rod rotator assembly  28  by a strap  62  that extends about the circumferential extent of the rod rotator assembly housing  42 . However, in other embodiments, the sensor may be coupled to the housing by other suitable type(s) of connection(s) (e.g., alone or in combination with the strap), such as welded connection(s), adhesive connection(s), fastener connection(s), other suitable type(s) of connection(s), or a combination thereof. In addition, the target  54  is part of a mounting assembly  64 , which is coupled to the top cap  44  via a clamp  66  of the mounting assembly  64 . As discussed in detail below, the mounting assembly  64  includes a bracket having a lower lip configured to engage a bottom surface of the top cap  44 , and the clamp  66  is configured to selectively engage an engagement surface (e.g., top surface) of the top cap  44 , thereby coupling the mounting assembly  64  to the top cap  44 . While the mounting assembly includes a bracket and a clamp in the illustrated embodiment, in other embodiments, the mounting assembly may include other and/or additional component(s) (e.g., fastener(s), latch(es), etc.) configured to couple the target to the top cap. Furthermore, while the target  54  is coupled to the top cap  44  via the mounting assembly  64  in the illustrated embodiment, in other embodiments, the target may be coupled to the top cap by any other suitable type(s) of connection(s) (e.g., alone or in combination with the mounting assembly), such as adhesive connection(s), a press-fit connection, a threaded connection, fastener connection(s), welded connection(s), other suitable type(s) of connection(s), or a combination thereof. 
     While the target  54  is coupled to the top cap  44  in the illustrated embodiment, in other embodiments, the target may be coupled to another suitable rotating portion of the rod rotator assembly. For example, in certain embodiments, the target may be coupled to the main gear, which is configured to drive the top cap to rotate, or the target may be coupled to a rotating shaft of a motor (e.g., electric motor), which is configured to drive the top cap to rotate. In such embodiments, the body of the sensor may be coupled to an internal surface of the rod rotator assembly housing by any suitable connection(s) (e.g., adhesive connection(s), welded connection(s), fastener connection(s), etc.). Furthermore, in certain embodiments, the target may be coupled to the top cap radially inward from the outer wall of the rod rotator assembly housing. In such embodiments, the body of the sensor may be coupled to an internal surface of the rod rotator assembly housing by any suitable connection(s) (e.g., adhesive connection(s), welded connection(s), fastener connection(s), etc.). In addition, in certain embodiments, the sensor, the target, and in certain embodiments, mounting component(s) for the sensor and/or the target (e.g., the strap for mounting the sensor, the mounting assembly for mounting the target, etc.) may be sold as a kit (e.g., retrofit kit) configured to provide polish rod rotation monitoring functionality to an artificial lift system. 
     In the illustrated embodiment, the rotation monitoring assembly  12  includes a single target  54  extending about a portion of the circumferential extent of the rod rotator assembly  28 . However, in other embodiments, the rotation monitoring assembly may include additional targets, and each target may have any suitable circumferential extent. For example, in certain embodiments, the rotation monitoring assembly may include 2, 3, 4, 5, 6, or more targets. The targets may be spaced apart from one another along the circumferential axis, and the circumferential spacing between targets may be substantially equal or varied. Furthermore, in certain embodiments, the rotation monitoring assembly may include a single target that extends about an entire circumferential extent of the rod rotator assembly (e.g., such that the contact element of the sensor maintains contact with the contact surface of the target throughout the rotation of the rotating portion, such as the top cap, of the rod rotator assembly). 
     The sensor  48  may output the sensor signal indicative of the position of the contact element  50  relative to the body  52  via a wired or wireless connection. In the illustrated embodiment, a sensor cable  68  extends from the sensor  48  toward a monitoring/control system, and the sensor signal may be output via the sensor cable  68 . However, in other embodiments, the sensor may be communicatively coupled to the monitoring/control system via a wireless connection. The wireless connection may utilize any suitable wireless communication protocol, such as Bluetooth, WiFi, radio frequency identification (RFID), a proprietary protocol, or a combination thereof. 
       FIG. 4  is a schematic perspective view of the mounting assembly  64  of the rotation monitoring assembly of  FIG. 3 . As previously discussed, the target  54  is part of the mounting assembly  64 , and the mounting assembly  64  is configured to couple to the top cap of the rod rotator assembly via the clamp  66 . In the illustrated embodiment, the mounting assembly  64  includes a bracket  70  having a lower lip  72  configured to engage a bottom surface of the top cap. In addition, the clamp  66  includes a threaded shaft  74  and a contact pad  76  coupled to the threaded shaft  74 . As illustrated, the threaded shaft  74  is engaged with a nut  78  of the bracket  70 . The contact pad  76  is configured to selectively engage the engagement surface (e.g., the top surface) of the top cap, and rotation of the threaded shaft  74  is configured to control the position of the contact pad  76  relative to the lower lip  72 . To couple the mounting assembly  64  to the top cap, the lower lip  72  of the bracket  70  is engaged with the bottom surface of the top cap, and the threaded shaft  74  of the clamp  66  is rotated such that the contact pad  76  of the clamp  66  engages the engagement surface of the top cap. While the clamp  66  includes the threaded shaft  74 , and the bracket  70  includes the nut  78  in the illustrated embodiment, in other embodiments, the mounting assembly may include any other suitable device(s)/system(s) configured to selectively drive the contact pad to engage the top surface of the top cap, such as latch(es), hydraulic actuator(s), electromechanical actuator(s), etc. 
     In the illustrated embodiment, the target  54  is part of the bracket  70 , such that the contact surface  56  of the target  54  is formed on the bracket  70 . However, in other embodiments, the target may be formed as a separate element and coupled to the bracket. Furthermore, as previously discussed, the longitudinal extent of the contact surface  56  varies along the circumferential extent of the target  54 . In the illustrated embodiment, the longitudinal extent of the contact surface  56  varies substantially continuously along the circumferential extent of the target  54 . As used herein, “varies substantially continuously” refers to a continuous variation, or variations having multiple changes in magnitude (e.g., longitudinal extent), as compared to single-magnitude discrete variations. While the longitudinal extent of the contact surface varies substantially continuously along the circumferential extent of the target in the illustrated embodiment, in other embodiments, the longitudinal extent of the contact surface may vary discretely with single-magnitude variations along the circumferential extent of the target. In the illustrated embodiment, the contact surface  56  forms a wave pattern (e.g., substantially continuous wave pattern). However, in other embodiments, the contact surface may form any other suitable pattern (e.g., linear ramped pattern, curved ramped pattern, notched pattern, etc.) to facilitate monitoring of the rotation of the polish rods. For example, in embodiments in which the contact surface has a ramped pattern (e.g., the longitudinal extent of the contact surface increases or decreases substantially continuously along the circumferential extent of the target), the rotation monitoring assembly may facilitate determination of the angular position of the polish rods (e.g., by utilizing a stored relationship between position of the contact element of the sensor and an angular position of the polish rods). 
     While the sensor is coupled to the housing of the rod rotator assembly and the target is coupled to a rotating portion of the rod rotator assembly in the illustrated embodiment, in other embodiments, the sensor may be coupled to another suitable non-rotating component of the polish rod connection assembly, such as the carrier, and the target may be coupled to another suitable rotating component of the polish rod connection assembly, such as the polish rod clamp(s). Furthermore, in certain embodiments, the sensor may be coupled to a rotating component of the polish rod connection assembly (e.g., the top cap, the polish rod clamp(s), etc.), and the target may be coupled to a non-rotating component of the polish rod connection assembly (e.g., the rod rotator assembly housing, the carrier, etc.). 
       FIG. 5  is a perspective view of the rod rotator assembly  28  of the polish rod connection assembly of  FIG. 2 , in which a portion of the rod rotator assembly  28  is cut away, and an embodiment of a rotation monitoring assembly  12 ′. As previously discussed, the rod rotator assembly  28  includes a housing  42 , which is supported by the carrier. In the illustrated embodiment, the housing  42  includes a base  80  and a body  82  extending upwardly from the base  80  along the longitudinal axis  58  of the rod rotator assembly  28 . The body  82  forms a first opening  86  on an opposite longitudinal side of the housing  42  from the base  80 , and the first opening  86  provides access to an interior  88  of the housing  42 . Furthermore, in the illustrated embodiment, the base  80  of the housing  42  forms a second opening  90 . The openings in the housing  42  facilitate passage of the polish rod through the housing  42 . In certain embodiments, an annular bushing may be disposed within the second opening  90 . In such embodiments, the annular bushing may be configured to contact the polish rod, thereby substantially blocking dirt and/or debris from entering the housing interior via the second opening. Furthermore, in certain embodiments, the annular bushing may be omitted. While the housing  42  has an annular shape in the illustrated embodiment, in other embodiments, the housing may have any other suitable shape (e.g., polygonal, elliptical, irregular, etc.). 
     Furthermore, as previously discussed, the rod rotator assembly  28  includes a top cap  44  configured to rotate relative to the housing  42 . The top cap  44  is configured to rotate along the circumferential axis  60  of the rod rotator assembly  28 . Furthermore, as previously discussed, the top cap  44  is configured to support the polish rods via the polish rod clamp(s). In the illustrated embodiment, the top cap  44  includes a body  94  and a platform  96 . The body  94  extends through the first opening  86  in the housing  42  into the interior  88  of the housing  42 , and the platform  96  has an engagement surface  98  configured to engage the polish rod clamp(s), thereby supporting the polish rods. In the illustrated embodiment, the platform  96  of the top cap  44  has an opening  100  configured to facilitate passage of the polish rod (e.g., top polish rod) through the platform  96 . In addition, the body  94  of the top cap  44  is configured to be disposed outwardly from the polish rod along a radial axis  102  of the rod rotator assembly  28 , thereby facilitating passage of the polish rod through the body  94 . While the body  94  of the top cap  44  extends through the first opening  86  of the housing  42  into the interior  88  of the housing  42  in the illustrated embodiment, in other embodiments, the body may not extend into the housing interior (e.g., the body may be non-rotatably coupled to a component of the rod rotator assembly positioned at least partially outside of the housing, such as the main gear). Furthermore, in certain embodiments, the body of the top cap may be omitted (e.g., the platform of the top cap may be non-rotatably coupled to a component of the rod rotator assembly, such as the main gear). 
     In the illustrated embodiment, the rod rotator assembly  28  includes a main gear  104 , which is non-rotatably coupled to the body  94  of the top cap  44 . The main gear  104  may be non-rotatably coupled to the body  94  of the top cap  44  via any suitable type(s) of connection(s), such as welded connection(s), a press-fit connection, fastener connection(s), adhesive connection(s), other suitable type(s) of connection(s), or a combination thereof. As previously discussed, the main gear  104  is configured to be driven to rotate by a worm gear. In the illustrated embodiment, movement of the lever  46  drives the worm gear to rotate, thereby driving the main gear  104  to rotate. Due to the non-rotatable coupling between the main gear  104  and the body  94  of the top cap  44 , rotation of the main gear  104  drives the top cap  44  to rotate, thereby driving the polish rods to rotate via the contact between the engagement surface  98  of the top cap  44  and the polish rod clamp(s). While the main gear  104  is driven to rotate by a worm gear coupled to the lever  46  in the illustrated embodiment, in other embodiments, the main gear may be driven to rotate by a motor (e.g., electric motor, hydraulic motor, pneumatic motor, etc.). Furthermore, in certain embodiments, the main gear may be omitted, and a motor (e.g., electric motor, hydraulic motor, pneumatic motor, etc.) may drive the top cap to rotate, as discussed above with reference to  FIG. 3 . 
     In the illustrated embodiment, the rod rotator assembly  28  includes a bearing  106  disposed between the main gear  104  and the base  80  of the housing  42  along the longitudinal axis  58  of the rod rotator assembly  28 . The bearing  106  enables the main gear  104  to rotate relative to the housing  42 . In the illustrated embodiment, the bearing  106  includes a ball bearing (e.g., including multiple bearing balls between two races). However, in other embodiments, the bearing may include other suitable type(s) of bearing(s) (e.g., alone or in combination with one or more ball bearings), such as roller bearing(s), fluid bearing(s), other suitable type(s) of bearing(s), or a combination thereof. Furthermore, while the rod rotator assembly  12  includes a single bearing  106  in the illustrated embodiment, in other embodiments, the rod rotator assembly may include more or fewer bearings (e.g., 0, 2, 3, 4, or more). For example, in certain embodiments, the bearing may be omitted. In such embodiments, a bushing may be disposed between the main gear and the base of the housing along the longitudinal axis of the rod rotator assembly. 
     In the illustrated embodiment, the rod rotator assembly  28  includes a first seal  108  (e.g., o-ring, etc.) disposed between the housing  42  and the top cap body  94  along the radial axis  102 , thereby establishing a seal between the top cap body  94  and the housing  42 . The first seal  108  is configured to substantially block dirt and/or debris from entering a cavity between the top cap body and the housing body. While the rod rotator assembly includes a single seal between the housing and the top cap body in the illustrated embodiment, in other embodiments, the rod rotator assembly may include more or fewer seals between the housing and the top cap body (e.g., 0, 2, 3, 4, or more). For example, in certain embodiments, the first seal may be omitted. Furthermore, in certain embodiments, the rod rotator assembly may include a second seal (e.g., o-ring, etc.) disposed between the platform of the top cap and the body of the housing along the radial axis. The second seal may be configured to substantially block dirt and/or debris from entering the cavity between the top cap body and the housing body. While a single seal disposed between the platform and the housing body along the radial axis is disclosed above, in certain embodiments, more or fewer seals (e.g., 0, 2, 3, 4, or more) may be disposed between the platform and the housing body along the radial axis. 
     In the illustrated embodiment, the rotation monitoring assembly  12 ′ includes a sensor  48  having a contact element  50  and a body  52 . The sensor  48  is configured to output a sensor signal indicative of a position of the contact element  50  relative to the body  52 . As previously discussed, in certain embodiments, the sensor  48  includes a linear variable differential transformer (LVDT) having a core coupled to the contact element  50  and multiple coils extending around a central passage of the body  52 . In such embodiments, the sensor signal may correspond to a voltage output by the LVDT, and movement of the core within the central passage may vary the voltage output/sensor signal. Additionally or alternatively, the sensor  48  may include any other suitable type(s) of position monitoring device(s), such as linear potentiometer(s), optical sensor(s), other suitable type(s) of position monitoring device(s), or a combination thereof. While the rotation monitoring assembly  12 ′ includes a single sensor  48  in the illustrated embodiment, in other embodiments, the rotation monitoring assembly may include multiple sensors (e.g., distributed about the circumferential axis  60  of the rod rotator assembly  28 ). 
     In the illustrated embodiment, the rotation monitoring assembly  12 ′ includes a mount  110  that couples the body  52  of the sensor  48  to the body  82  of the housing  42 . As illustrated, the mount  110  includes an arcuate support  112  that extends about a portion of a periphery of the body  82  of the housing  42  along the circumferential axis  60  of the rod rotator assembly  28 . In the illustrated embodiment, the arcuate support  112  is coupled to the body  82  of the housing  42  via fasteners  114 . However, in other embodiments, the arcuate support may be coupled to the body of the housing via other suitable type(s) of connection(s) (e.g., alone or in combination with the illustrated fastener connection), such as welded connection(s), adhesive connection(s), a press-fit connection, other suitable type(s) of connection(s), or a combination thereof. Furthermore, in the illustrated embodiment, the mount  110  includes two brackets  116  coupled to the arcuate support  112  and to the body  52  of the sensor  48 . Accordingly, the body  52  of the sensor  48  is coupled to the housing  42  via the brackets  116  and the arcuate support  112 . In the illustrated embodiment, each bracket  116  is configured to couple to the sensor body  52  via a clamped connection (e.g., to enable adjustment of the position of the sensor body  52  along the longitudinal axis  58 ). However, in other embodiments, at least one bracket may be coupled to the sensor body via other suitable type(s) of connection(s) (e.g., alone or in combination with the clamped connection), such as fastener connection(s), adhesive connection(s), a press-fit connection, other suitable type(s) of connection(s), or a combination thereof. Furthermore, in the illustrated embodiment, each bracket  116  is coupled to the arcuate support  112  via a fastener connection. However, in other embodiments, at least one of the brackets may be coupled to the arcuate support via other suitable type(s) of connection(s) (e.g., alone or in combination with the illustrated fastener connection), such as welded connection(s), adhesive connection(s), other suitable type(s) of connection(s), or a combination thereof. Furthermore, while the mount  110  includes two brackets  116  in the illustrated embodiment, in other embodiments, the mount may include more or fewer brackets (e.g., 0, 1, 3, 4, or more). 
     While the body  52  of the sensor  48  is coupled to the arcuate support  112  via bracket(s)  116  in the illustrated embodiment, in other embodiments, the sensor body may be coupled to the arcuate support via other suitable type(s) of connection(s) (e.g., alone or in combination with the bracket(s)), such as adhesive connection(s), fastener connection(s), welded connection(s), a press-fit connection, other suitable type(s) of connection(s), or a combination thereof. Furthermore, while the mount  110  includes the arcuate support  112  in the illustrated embodiment, in other embodiments, the mount may include any other suitable structure(s) to facilitate coupling the sensor body to the housing (e.g., alone or in combination with the arcuate support), such as an annular support, support(s) having other suitable shape(s), or a combination thereof. In addition, in certain embodiments, the mount may be omitted, and the sensor body may be coupled to the housing via other suitable type(s) of connection(s), such as the strap disclosed above with reference to  FIG. 3 , welded connection(s), adhesive connection(s), fastener connection(s), other suitable type(s) of connection(s), or a combination thereof. Furthermore, while the body  52  of the sensor  48  is coupled to the body  82  of the housing  42  in the illustrated embodiment, in other embodiments, the body of the sensor may be coupled to another suitable portion of the housing, such as the base. 
     In addition, the rotation monitoring assembly  12 ′ includes a target  54 ′ non-rotatably coupled to the platform  96  of the top cap  44 , such that the target  54 ′ rotates with the top cap  44 . The target  54 ′ includes a contact surface  56 ′ configured to engage the contact element  50  of the sensor  48 . In addition, a longitudinal extent of the contact surface  56 ′ (e.g., extent of the contact surface along the longitudinal axis  58  of the rod rotator assembly  28 ) varies (e.g., substantially continuously) along a circumferential extent of the target  54 ′ (e.g., extent of the target along the circumferential axis  60  of the rod rotator assembly  28 ). Due to the variation in the longitudinal extent of the contact surface  56 ′ along the circumferential extent of the target  54 ′, the contact surface  56 ′ may drive the contact element  50  of the sensor  48  to move relative to the sensor body  52  as the top cap  44  rotates relative to the rod rotator assembly housing  42 . Accordingly, the sensor signal indicative of the position of the contact element  50  relative to the body  52  may vary as the top cap  44  rotates. As previously discussed, the sensor signal may be monitored (e.g., by a controller having a memory and a processor) to identify whether the polish rods are not rotating or are not rotating at a target rate, thereby enabling an operator to perform maintenance operations on the artificial lift system (e.g., on the rod rotator assembly). In addition, because the longitudinal extent of the contact surface varies (e.g., substantially continuously) along the circumferential extent of the target, a non-rotating/improperly rotating polish rod may be identified rapidly, as compared to utilizing a rotation monitoring assembly that identifies presence of a rotating target at the location of a non-rotating sensor, which may only identify non-rotation/improper rotation of a polish rod after a substantial portion of a rotation of the top cap (e.g., which may only rotate once per 40-50 oscillations of the pump jack). 
     In the illustrated embodiment, the target  54 ′ is annular and extends about an entire periphery of the platform  96  of the top cap  44 . Accordingly, the contact element  50  of the sensor  48  may engage the contact surface  56 ′ of the target  54 ′ while the target  54 ′ is an any orientation along the circumferential axis  60 . However, in other embodiments, the target may be arcuate and extend about a portion of the periphery of the platform of the top cap. In the illustrated embodiment, the target  54 ′ is non-rotatably coupled to the platform  96  of the top cap  44  via fasteners  120 . However, in other embodiments, the target may be non-rotatably coupled to the top cap via any other suitable type(s) of connection(s) (e.g., alone or in combination with the fasteners), such as welded connection(s), adhesive connection(s), a press-fit connection, other suitable type(s) of connection(s), or a combination thereof. 
     As previously discussed, the longitudinal extent of the contact surface  56 ′ varies along the circumferential extent of the target  54 ′. In the illustrated embodiment, the longitudinal extent of the contact surface  56 ′ varies substantially continuously along the circumferential extent of the target  54 ′. As previously discussed, “varies substantially continuously” refers to a continuous variation, or variations having multiple changes in magnitude (e.g., longitudinal extent), as compared to single-magnitude discrete variations. While the longitudinal extent of the contact surface varies substantially continuously along the circumferential extent of the target in the illustrated embodiment, in other embodiments, the longitudinal extent of the contact surface may vary discretely with single-magnitude variations along the circumferential extent of the target. In the illustrated embodiment, the contact surface  56 ′ forms a wave pattern (e.g., substantially continuous wave pattern). However, in other embodiments, the contact surface may form any other suitable pattern (e.g., linear ramped pattern, curved ramped pattern, notched pattern, etc.) to facilitate monitoring of the rotation of the polish rods. For example, in embodiments in which the contact surface has a ramped pattern (e.g., the longitudinal extent of the contact surface increases or decreases substantially continuously along the circumferential extent of the target), the rotation monitoring assembly may facilitate determination of the angular position of the polish rods (e.g., by utilizing a stored relationship between position of the contact element of the sensor and an angular position of the polish rods). 
     In certain embodiments, the contact element  50  is biased away from the body  52  (e.g., by a spring or other suitable biasing element). Accordingly, the contact element  50  of the sensor  48  is urged into contact with the contact surface  56 ′ of the target  54 ′. Furthermore, in certain embodiments (e.g., in embodiments in which the target extends about the entire circumferential extent of the top cap), the contact element of the sensor may be coupled to the contact surface of the target. For example, the contact surface of the target may be formed on a rail or track that extends along the circumferential axis of the rod rotator assembly, and the contact element may include an engagement element (e.g., wheel, slider, etc.) engaged with the rail or track. 
     While the target  54 ′ is coupled to the top cap  44  in the illustrated embodiment, in other embodiments, the target may be coupled to another suitable rotating portion of the rod rotator assembly. For example, in certain embodiments, the target may be coupled to the main gear, or the target may be coupled to a rotating shaft of a motor (e.g., electric motor), which is configured to drive the top cap to rotate. In such embodiments, the body of the sensor may be coupled to an internal surface of the rod rotator assembly housing by any suitable connection(s) (e.g., adhesive connection(s), welded connection(s), fastener connection(s), etc.). Furthermore, in certain embodiments, the target may be coupled to the top cap radially inward from the body of the rod rotator assembly housing. In such embodiments, the body of the sensor may be coupled to an internal surface of the rod rotator assembly housing by any suitable connection(s) (e.g., adhesive connection(s), welded connection(s), fastener connection(s), etc.). In addition, in certain embodiments, the sensor, the target, and in certain embodiments, mounting component(s) for the sensor and the target (e.g., the target fasteners, the sensor mount etc.) may be sold as a kit (e.g., retrofit kit) configured to provide polish rod rotation monitoring functionality to an artificial lift system. 
     In the illustrated embodiment, the rotation monitoring assembly  12 ′ includes a single target  54 ′ extending about the entire periphery of the top cap  44 . However, in other embodiments, the rotation monitoring assembly may include multiple targets, in which each target extends about a portion of the periphery of the top cap. For example, in certain embodiments, the rotation monitoring assembly may include 2, 3, 4, 5, 6, or more targets. The targets may be spaced apart from one another along the circumferential axis, and the circumferential spacing between targets may be substantially equal or varied. 
     The sensor  48  may output the sensor signal indicative of the position of the contact element  50  relative to the body  52  via a wired or wireless connection. In the illustrated embodiment, a sensor cable  68  extends from the sensor  48  toward a monitoring/control system, and the sensor signal may be output via the sensor cable  68 . However, in other embodiments, the sensor may be communicatively coupled to the monitoring/control system via a wireless connection. The wireless connection may utilize any suitable wireless communication protocol, such as Bluetooth, WiFi, radio frequency identification (RFID), a proprietary protocol, or a combination thereof. 
     While the sensor is coupled to the housing of the rod rotator assembly and the target is coupled to a rotating portion of the rod rotator assembly in the illustrated embodiment, in other embodiments, the sensor may be coupled to another suitable non-rotating component of the polish rod connection assembly, such as the carrier, and the target may be coupled to another suitable rotating component of the polish rod connection assembly, such as the polish rod clamp(s). Furthermore, in certain embodiments, the sensor may be coupled to a rotating component of the polish rod connection assembly (e.g., the top cap, the polish rod clamp(s), etc.), and the target may be coupled to a non-rotating component of the polish rod connection assembly (e.g., the rod rotator assembly housing, the carrier, etc.). 
     While a contact sensor is disclosed above with regard to the embodiments of  FIGS. 3-5 , in certain embodiments, the sensor may include a non-contact sensor, such as an inductive sensor, a capacitance sensor, an optical sensor, a radar sensor, a LIDAR sensor, an ultrasonic sensor, other suitable non-contact sensor(s), or a combination thereof. In such embodiments, the sensor may be directed toward a respective surface of the target, and a longitudinal extent of the respective surface of the target (e.g., property of the target) may vary (e.g., substantially continuously) along the circumferential extent of the target. The sensor may output a sensor signal indicative of a distance between the sensor and the respective surface of the target, which is based on the longitudinal extent of the respective surface (e.g., the property of the target). Accordingly, the rotation monitoring assembly may facilitate monitoring polish rod rotation/rotation rate based on the variation in distance between the sensor and the respective surface of the target. While the circumferentially varying property of the target includes the longitudinal extent of the contact surface/respective surface in the embodiments disclosed above, in certain embodiments, the target may have another property that varies (e.g., substantially continuously) along the circumferential extent of the target, such as color, capacitance, electrical conductivity, or another suitable property. For example, a surface of the target facing the sensor may vary (e.g., substantially continuously) in color along the circumferential extent of the target, and the sensor may include a camera configured to detect the color. Accordingly, the camera may output a sensor signal indicative of the color, thereby facilitating monitoring of polish rod rotation/rotation rate based on the variation in color of the surface of the target. As used herein with regard to color, “varies substantially continuously” refers to a continuous color variation, or variations having multiple changes in color, as compared to single-color discrete variations. By way of further example, the target may vary (e.g., substantially continuously) in capacitance or electrical conductivity along the circumferential extent of the target, and the sensor may include a capacitance sensor or an electrical conductivity sensor configured to detect the capacitance/electrical conductivity. Accordingly, the sensor may output a sensor signal indicative of the capacitance/electrical conductivity, thereby facilitating monitoring of polish rod rotation/rotation rate based on the variation in capacitance/electrical conductivity of the target. As previously discussed, “varies substantially continuously” refers to a continuous variation, or variations having multiple changes in magnitude (e.g., capacitance, electrical conductivity, etc.), as compared to single-magnitude discrete variations. 
     In addition, in certain embodiments, the sensor may include a capacitive sensor (e.g., coupled to one of the housing or the rotating portion of the rod rotator assembly) that extends about at least a portion of the circumferential extent of the rod rotator assembly, and a target (e.g., coupled to the other of the housing or the rotating portion of the rod rotator assembly) may be detectable by the capacitive sensor. In such embodiments, the sensor may output a sensor signal indicative of the circumferential position of the target, thereby facilitating monitoring of the polish rod rotation/rotation rate. Furthermore, in certain embodiments, the sensor may include multiple optical sensors (e.g., coupled to one of the housing or the rotating portion of the rod rotator assembly) distributed about at least a portion of the circumferential extent of the rod rotator assembly, and a target (e.g., coupled to the other of the housing or the rotating portion of the rod rotator assembly) may be detectable by the optical sensors. In such embodiments, the sensor may output a sensor signal indicative of the circumferential position of the target, thereby facilitating monitoring of the polish rod rotation/rotation rate. 
     While only certain features have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).