PROGRESSING CAVITY PUMP IN WHICH ROTOR DEPTH CAN BE DETERMINED WITHOUT DISASSEMBLY OF ABOVE GROUND EQUIPMENT, AND METHODS, SYSTEMS AND TOOLS RELATING TO SAME

Abstract

An improved progressing cavity pump, methods of making the same, methods of using the same, and methods of retrofitting conventional progressing cavity pumps are disclosed. The improved progressing cavity pump has an improved polished rod, which is connectable to a slider tool, that enables the rod string, including the pump's rotor to be lowered in the production tubing without requiring disassembly of the above ground equipment. Preferably, the slider tool functions to extend the length of the improved polished rod, and the connection between the slider tool and the improved polished rod is preferably configured to ensure that the outside diameter of the connection is no larger than the passageways of the above ground equipment it needs to pass through, when it is lowered. Also disclosed is an improved polished rod clamp. An indicator which enables an operator on the ground to visually determine whether a progressing cavity pump is operating, or whether it is operating correctly is also disclosed.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of oil and gas wellhead equipment. More particularly, the present invention relates to progressing cavity pumps.

BACKGROUND OF THE INVENTION

[0002] Progressing cavity pumps, which are also known as screw pumps and Moineau pumps, are commonly used for oil and gas well recovery and extraction projects. This type of pump is used to lift fluid from oil and gas wells where there is not enough reservoir pressure to lift the produced fluids to surface. They are increasingly used for artificial lift, and have been adapted to a range of challenging lift situations, including heavy oil production, high sand oil production, oil production from gassy wells, and oil production from directional and horizontal wells.

[0003] Progressing cavity pumps operate by lifting fluids to the surface by employing a positive displacement principle. A typical progressing cavity pump features a suction inlet at the end of production tubing which feeds into an elongated casing lining a well bore. The production tubing is typically formed by connecting together a number of tubing sections into a string. The progressing cavity pump includes a helical `worm` rotor and stator assembly. The stator is run into the casing on the bottom of the production tubing, while the rotor is run into the production tubing, connected to the bottom of a continuous sucker rod, or a string of sucker rods 26. The top end of the sucker rod, or sucker rod string is connected to a polished rod, which is in turn connected to an above ground drive system 30.

[0004] Above ground drive systems are typically electrically or gas/hydraulic driven. The above ground drive system which moves the rotor in an eccentric fashion within the stator. Cavities formed between the rotor and the stator draw in fluid, and are `progressed` through the rotor and stator assembly and up the production tubing to the surface where it is discharged to the flow line through the pumping tee.

[0005] Connected above the pumping tee, a stuffing box includes a seal to keep pressurized well fluids from escaping from the production tubing. The stuffing box preferably forms a tight seal with the polished rod to divert the produced fluids out of the pumping tee into the flow line.

[0006] One problem with prior art progressing cavity pumps is that once the progressing cavity pump has been installed, there is no way to check or adjust the depth of the rotor correctly, without disassembling major portions of the above ground equipment. In fact, once the rotor has been installed to the required depth, the standard procedure is to run the progressing cavity pump to acquire production, without ever checking or adjusting the rotor. However, if the rotor was installed at an incorrect depth to begin with, or has slipped down in the production tubing overtime during its operation, the lifespan and efficiency of the progressing cavity pump may be reduced significantly.

[0007] Another problem with prior art progressing cavity pumps is that they need to be serviced regularly and often to flush out any build up of debris such as sand, wax, paraffin's, and shale's, and the service is difficult and time consuming. However, the flush-by service also requires disassembling major portions of the above ground equipment.

[0008] Prior art methods for checking the depth of the rotor, and for effecting the flush-by service on prior art progressing cavity pumps involve disassembling major portions of the above ground equipment, including the above ground drive system, the stuffing box, and the piping tee, to allow the rotor attached to the end of the rod sting to be lowered within the production tubing to the bottom out in the stator or to some other reference point, as is needed to set the rotor to the correct depth. This is a difficult and time consuming, labour intensive process, and leads to significant downtime.

[0009] Accordingly, there is a continued need for improvement in progressing cavity pumps.

SUMMARY OF THE INVENTION

[0010] What is desired is an improved progressing cavity pump, including an improved polished rod, and slider tool, and methods that provide a safe way to check and adjust the depth of the rotor after the progressing cavity pump has been installed and pumping for a period of time, without needing to disassemble major portions of the above ground equipment.

[0011] Also desirable is an improved progressing cavity pump, including an improved polished rod, and slider tool, and methods that permit checking and adjusting the depth of the rotor after flushing out debris buildup in a progressing cavity pump, without needing to disassemble major portions of the above ground equipment.

[0012] According to an aspect of the present invention, there is disclosed an improved progressing cavity pump, having an improved polished rod that is attachable to a slider tool, that enables the rod string, including the rotor to be lowered into the production tubing without requiring disassembly of the above ground equipment. Preferably, the slider tool functions to extend the length of the improved polished rod, and the connection between the slider tool and the improved polished rod is preferably configured to ensure that the outside diameter of the connection is no larger than the passageways of the above ground equipment it needs to pass through, when it is lowered.

[0013] According to another aspect of the present invention, there is disclosed an improved polished rod clamp, which preferably, has at least one extended nut.

[0014] According to another aspect of the present invention, there is disclosed an indicator which enables an operator on the ground to visually determine whether a progressing cavity pump is operating, or whether it is operating correctly.

[0015] According to another aspect of the present invention, there is disclosed a method of making the above improved progressing cavity pump by replacing a conventional polished rod in a conventional progressing cavity pump with the improved polished rod according to an embodiment of the present invention.

[0016] According to another aspect of the present invention, there is disclosed a method of checking or adjusting the depth of the rotor in the above improved progressing cavity pump.

[0017] According to another aspect of the present invention, there is disclosed a method of flushing the above improved progressing cavity pump.

[0018] According to another aspect of the present invention, there is disclosed a progressing cavity pump system comprising the above improved polished rod and the above slider tool. Preferably, the system may further include one or more of the above improved polished rod clamp and the above indicator.

[0019] According to another aspect of the present invention, there is disclosed a kit comprising the above improved polished rod, and the above slider tool. Preferably, the kit may further include one or more of the above improved polished rod clamp and the above indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Reference will now be made to the preferred embodiments of the present invention with reference, by way of example only, to the following drawings in which:

[0021] FIG. 1 is a diagram of a ground level portion of a progressing cavity pump, according to an embodiment of the present invention;

[0022] FIG. 2 is a diagram of a below ground portion of the progressing cavity pump of FIG. 1;

[0023] FIG. 3 is a side view of a prior art polished rod;

[0024] FIG. 4 is a side view of a polished rod according to an embodiment of the present invention;

[0025] FIG. 5 is a side view of a polished rod according to another embodiment of the present invention;

[0026] FIG. 6 is a more detailed view of the polished rod of FIG. 4;

[0027] FIG. 7 is a side view of a slider tool connected to a polished rod according to another embodiment of the present invention;

[0028] FIG. 8 is a side view of a slider tool connected to a polished rod according to another embodiment of the present invention;

[0029] FIG. 9 is a diagram of the ground level portion of the progressing cavity pump of FIG. 1, with the slider tool of FIG. 7 installed;

[0030] FIG. 10 is a cross-sectional view of a polished rod clamp having extended nuts, according to another embodiment of the present invention;

[0031] FIG. 11 is a perspective view of the extended nut of FIG. 10; and

[0032] FIG. 12 is a side view of an indicator according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The present invention is described in more detail with reference to exemplary embodiments thereof as shown in the appended drawing. While the present invention is described below including preferred embodiments, it should be understood that the present invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments which are within the scope of the present invention as disclosed and claimed herein.

[0034] A surface-driven progressing cavity pump 10 is shown in FIGS. 1 and 2, according to an embodiment of the present invention. FIG. 1 shows the ground level portion of the progressing cavity pump 10, while FIG. 2 shows the below ground portion, which continues from the ground portion shown of FIG. 1. Starting with FIG. 1, there is shown a well bore 12 that has been drilled into the ground 14. Production tubing 16 feeds into an elongated casing 18 lining the well bore 12. The production tubing 16 is typically formed by connecting together a number of tubing sections into a string of tubing sections.

[0035] A pumping tee 20 is connected to the top of the production tubing 16 to provide a flow connection from the production tubing 16 to a flow line 22.

[0036] A stuffing box 24 connected to the top of the pumping tee 20, includes a seal to keep pressurized well fluids from escaping from the production tubing 16.

[0037] A drive system 26 is mounted to the top of the stuffing box 24. Drive systems 26 may be electrically or gas/hydraulically driven. In the example shown in FIG. 1, the drive system 26 is electrically driven. In an electrically driven drive system 26, gas engine driven generators may be used to supply electricity where line power is not available. According to the example shown in FIG. 1, the electrically driven drive system 26, includes an electric motor 28, a transmission unit 30, and a belt and sheave reduction 32 to provide additional speed adjustment. It is also contemplated that a hydraulic transmission consisting of an engine driven pump driving a hydraulic motor may be used as an alternative to the electrically driven drive system 26. Furthermore, geared systems and inline electric or hydraulic systems, may also be used, as will be appreciated by persons skilled in the art. All such embodiments are comprehended by the present invention.

[0038] The surface driven progressing cavity pump 10 includes a polished rod 34, which is inserted from the top of the drive system 26, through the transmission unit 30, the stuffing box 24, the pumping tee 20, to project its one end, herein referred to as its bottom end 36, into the production tubing 16, while its other end, herein referred to as its top end 38, projects upwardly from the drive system 26. The transmission 30 features a hollow drive shaft 40 extending upwardly. The top of the hollow drive shaft 40 preferably includes a receiver for supporting and engaging a polished rod clamp 42, which may be clamped to the top end of the polished rod 34. By the engagement of the receiver at the top of the hollow drive shaft 40 with the polished rod clamp 42, rotation of the hollow drive shaft 40 by the transmission unit 30 is translated to a rotation of the polished rod 34.

[0039] Accordingly, it will now be understood that the drive system 26 may be used to drive the rotation of the polished rod 34 of the surface driven progressing cavity pump 10, according to an embodiment of the present invention. As shown in FIG. 1, the bottom end 36 of the polished rod 42, which projects into the production tubing 16, is preferably connected to a rod string 44 via a rod coupler 46.

[0040] Preferably, the stuffing box 24 and the pumping tee 20 form tight seals with the polished rod 34 to divert the produced fluids out of the pumping tee 20 into the flow line 22, as the polished rod 34 is rotated by the drive system 26. Preferably, a "composite" pumping tee may be used, which clamps on to the polished rod 34 to support the rod string 44 and seal against the polished rod 34 to isolate produced well fluids. The composite pumping tee allows the stuffing box 24 and the drive system 26 to be serviced or removed safely without having to pull the rod string 44, connected to the polished rod 34 in the production tubing 16, in the ground 14.

[0041] With reference now to FIG. 2, the progressing cavity pump 10 preferably includes a helical `worm` rotor and stator assembly 48. The stator 50 is run into the casing 18 on the bottom of the production tubing 16, while the rotor 52 is run into the production tubing 16, connected to the bottom of a rod string 44. As will be appreciated, the rod string 44 may include a continuous sucker rod, an endless rod reel, a string of sucker rods 54, and the like, as well as combinations thereof. The top end of the rod string 44 is connected to the bottom end 36 of the polished rod 34, via the rod coupler 46, and as mentioned above, the polished rod 34 is in turn connected to the drive system 26.

[0042] As the rotor 52 begins to move in an eccentric fashion, driven by the drive system 26, cavities formed between the rotor 52 and the stator 50 draw in fluid, and are `progressed` through the rotor and stator assembly 48 and up the production tubing 16 to the surface where it is discharged to the flow line 22 connected to the pumping tee 20. Thus, rotation of the rod string 44 by means of the drive system 26 causes the rotor 52 to spin within the fixed stator 50, creating the pumping action necessary to produce fluids to the surface.

[0043] Preferably, the progressing cavity pump 10 may also include a tag bar 56 to allow the rotor 24 to be positively located relative to the stator 22. For example, some Installation methods include running the rotor 52 to the tag bar 56 and then spacing back to align the rotor 52 within the stator 50. The rotor space-out is unique to the pump geometry, well operating conditions, and rod string configuration, as is known in the art.

[0044] It is also contemplated that large progressing cavity pumps 10 may preferably include a no-turn device 58 to prevent the torque in the rotor and stator assembly 48 from loosening the connections between the tubing sections of the production tubing 16. Smaller progressing cavity pumps 10 with properly torqued tubing sections may not require no-turn devices 58 although a no-turn device may still be included as a precaution. In the example of the progressing cavity pump shown in FIGS. 1 and 2, the bottom of the no-turn device 58 provides the pump inlet 60 for the well fluids to be produced with the progressing cavity pump 10.

[0045] For comparison, a conventional polished rod 62 is shown in FIG. 3. The conventional polished rod 62 has an elongate cylindrical body 64. The top and bottom ends 38,36 of the body 64, have threaded male portions 66, which are sized and shaped to form threaded connections with one end of a rod coupler 46 having a matching threaded female portion. The other end of the rod coupler 46 has a threaded female end which may in turn form a threaded connection to, for example, a sucker rod 54, an endless rod reel, a rod string 44, and the like, having a matching threaded male portion.

[0046] A polished rod 34 according to an embodiment of the present invention is shown in FIGS. 4 and 6. As shown, the polished rod 34 has an elongate body 64, which is substantially cylindrical in shape according to a preferred embodiment of the invention. The body 64 of the polished rod 34 has a top end 38 and a bottom end 36. The top and bottom ends 38,36 have threaded male portions 66, which are sized and shaped to form threaded connections with one end of a rod coupler 46 having a matching threaded female portion, in the same way as the above noted conventional polished rod 62. And as noted above, the other end of the rod coupler 46 has a threaded female end which may in turn form a threaded connection to a sucker rod 54, an endless rod reel, a rod string 44, and the like, having a matching threaded male portion.

[0047] By way of example, the diameter of the body 64 of the polished rod 34 may be sized in a range of 3/4 inch to 21/2 inches, and its length may be sized in a range of 6 to 60 feet, to coincide with standard sizes, as is known in the art. Similarly, the diameters of the threaded male portions 66 may be sized in a range of 3/4 inch to 21/2 inches, and their lengths may be sized in a range of 3/4 inch to 3 inches, to coincide with standard sizes of rod couplers 46, as is also known in the art.

[0048] However, in contrast to a conventional polished rod 62, the polished rod 34, according to the present invention preferably further includes a threaded extension 68 extending coaxially from the top, bottom, or both ends 38,36 of the body 64. FIGS. 4 and 6 show one example of such a threaded extension 68 extending from the top end 38 of the body 64. As can be seen in FIGS. 4 to 6, the threaded extensions 68 have diameters that are less than the diameters of the respective threaded male portions 66 from which they extend. Preferably, the diameters of the threaded extensions 68 may be sized in a range of 1/2 inch to 11/2 inches, and their lengths may be sized in a range of 3/4 inch to 4 inches. The smaller diameters of the threaded extensions 68, compared to the diameters of the threaded male portions 66, preferably provide substantially flat surfaces 70 between the edges of the threaded male portions 66 and the edges of the threaded extensions 68. FIG. 5 shows a polished rod 34 according to another embodiment of the present invention in which two threaded extensions 68 are provided to extend from both the top and bottom ends 38,36 of the body 64, defining two flat surfaces 70.

[0049] With reference now to FIG. 7, there is shown a slider tool 72, according to an embodiment of the present invention. As shown, the slider tool 72 preferably has an elongate body 64 with top and bottom ends 38,36. The top end 38 is configured to be gripped, held by, or attached to a flush-by/service rig.

[0050] Preferably, the top end 38 may be sized and shaped to the same as the end of a conventional sucker rod 54. Alternately, it is contemplated that the top end 38 of the slider tool 72 may have a threaded male portion 66, sized and shaped to be threadingly connectable to the flush-by/service rig, either directly, or via a rod coupler 46. The bottom end 36 may preferably have a threaded female portion 74, with a substantially flat bottom edge 76. Preferably, the threaded female portion 74 may be sized and shaped to match the threaded extension 68 of the polished rod 34. Accordingly, the diameter of the threaded female portion 74 of the slider tool 72 may be sized in a range of 1/2 inch to 11/2 inches, and the length may be sized in a range of 1/2 inch to 4 inches. By way of example, the diameter of the body 64 of the slider tool 72 may be sized in a range of 3/4 inch to 21/2 inches, and its length may be sized in a range of 1 to 7 feet.

[0051] However, it is also contemplated that the position of the threaded extension 68 and the matching threaded female portion 74 may be reversed between the polished rod 34 as shown in FIG. 8, to functionally effect the same threaded connection describe above. According to this embodiment of the present invention, the threaded extension 68 extends from the bottom end 36 of the slider tool 72, and the top end 38 of the polished rod 34 includes the threaded extension 68. The smaller diameter of the threaded extension 68 on the slider tool 72, compared to the diameter of outside diameter of the body 64, preferably provides a substantially flat surface 70 between the edge of the body 64 and the edge of the threaded extension 68. The top end 38 of the polished rod 34 preferably define a substantially flat top edge 76. All such embodiments are comprehended by the present invention.

[0052] What is important is that the slider tool 72 may be threadingly connected to the polished rod 34, via the threaded connection between the threaded extension 68 on one of the polished rod 34 and the slider tool 72, and the threaded female portion 74 on the other of the polished rod 34 and the slider tool 72. If the threaded extension 68 is provided on the polished rod 34, the substantially flat bottom edge 76 of the slider tool 72 may preferably be seated against the substantially flat surface 70 of the polished rod 34. Similarly, if the threaded extension 68 is provided on the slider tool 72, the substantially flat surface 70 of the slider tool 72 may preferably be seated against the substantially flat top edge 76 of the polished rod 34. As will be apparent from the discussion below, the body 64 of the slider tool 72 preferably has an outside diameter that will allow it to pass through the drive system 26, including through the transmission unit 30, through the stuffing box 24, and through the pumping tee 20, and into the production tubing 16, without needing to disassemble or move the above ground equipment out of the way. Preferably, the outside diameter of the body 64 of the slider tool 72 may be no larger than the outside diameter of the body 64 of the polished rod 34 to which it may be attached. Most preferably, the body 64 of the slider tool 72 may have substantially the same outside diameter as the outside diameter of the body 64 of the polished rod 34 to which it may be attached. However, it is also contemplated that the body 64 of the slider tool 72 may have an outside diameter that is smaller than the outside diameter of the body 64 of the polished rod 34 to which it may be attached.

[0053] Furthermore, the outside diameter of the slider tool 72 may be larger in some embodiments where the configuration of the above ground equipment permits the larger diameter slider tool 72 to pass therethrough. All such embodiments are comprehended by the present invention.

[0054] Preferably, the threaded extensions 68 may be formed in the body 64 of a conventional polished rod 62 (or a conventional sucker rod 54) by machining one or both ends 36,38, or the like. It will now be appreciated that conventional polished rods 62 may be retrofitted in this way to provide a threaded extension 68 at one or both ends 36,38, according to embodiments of the present invention. The machining step may require machining the threaded male portion 66 as well to extend it to a desired length, as some of its length will have been taken by the newly formed threaded extension 68. Alternately, a new polished rod 34 may be made to include the threaded extension 68 at one or both ends 36,38 of the body 64 from the start, by machining, or other methods which are known in the art. Further, it is contemplated that when modifying a conventional polished rod 62, or making a new polished rod 34, according to the present invention, the threaded male portion 66 may be omitted entirely at one or both ends 36,38 having a threaded extension 68, for example as shown in FIG. 7. However, it may be preferable to include a threaded male portion 66 at an end 36,38 having a threaded extension 68, as it will allow the same end to be connected to either a conventional rod coupler 46, or a slider tool 72. All such methods of making the polished rod 34, including the threaded extension 68, are comprehended by the present invention.

[0055] Referring now to FIG. 9, there is shown the above ground portion of the progressing cavity pump 10, with a slider tool 72 attached to the top end 38 of the polished rod 34, according to an embodiment of the present invention. In this example, the slider tool 72 is attached to the polished rod 34 in the manner described above, in that the threaded female portion 74 at the bottom end 36 of the slider tool 72 is threaded onto the threaded extension 68 on the top end 38 of the polished rod 34 to form a threaded connection. Preferably, the outside diameters of the bodies 64 of the polished rod 34 and slider tool 72 are substantially the same, so that the outside surface is substantially flush across the joint.

[0056] Preferably, the top end 36 of the slider tool 72 is sized and shaped for attachment to a flush-by or service rig, for example, which can lower the entire rod string 44, after the polished rod clamp 42 has been removed, down the production tubing 16 to a landed position at the bottom of the well bore 12, or to some other desired depth. It will now be apparent, that the slider tool 72, provides a removable extension to the polished rod 34, to allow lowering of the polished rod 34, and thus the connected rod string 44 and rotor 52, without needing to disassemble or move out of the way, the above ground drive system 26, the stuffing box 24, the piping tee 20, and any other intervening above ground equipment. After completing the rotor depth measuring procedure, or the flush-by service, the slider tool 72 may be used to raise the polished rod 34, together with the attached rod string 44 and rotor 52, to a desired level, allowing the polished rod 34 to be secured at that level by reattaching the polished rod clamp 42. With the polished rod 34 secured at the desired level, the slider tool 72 may then be disconnected from the polished rod 34, and stowed away until the next time the rotor depth may need to be checked, or the flush-by service may need to be performed.

[0057] FIG. 10 shows an enlarged view of a polished rod clamp 42, according to an embodiment of the present invention. Preferably, the polished rod clamp 42 has extended nuts 78, and matching extended bolts 80 that pass through apertures 82 in the polished rod clamp 42, from one side of the polished rod clamp 42 to the opposite side, to threadingly engage the extended nuts 78. In FIG. 9, three apertures 82 are shown without the extended nuts 78 and extended bolts 80 attached for purposes of illustration. An example of an extended nut 78 is shown in more detail in FIG. 11. As will be appreciated by persons skilled in the art, tightening the extended nuts 78 onto the extended bolts 80, secures the polished rod clamp 42 to the polished rod 34. It has been found that the polished rod clamp 42 with the extended nuts 78, makes installation and removal of the polished rod clamp 42 easier for a user to accomplish. In particular, the increased surface area of the extended nuts 78, and the increased distance they project out from the sides of the polished rod clamp 42, makes it easier for a user to access them with conventional tools in the field. This configuration makes removal and installation of the polished rod clamp 42 easier and therefore safer. Good results have been obtained with extended nuts 78 having a length a range of 3/4 inch to 11/2 inches.

[0058] Referring now to FIG. 12 there is shown an indicator 84, according to an embodiment of the present invention. The indicator 84 is preferably sized and shaped to be threadingly connected to the top end 36 of the polished rod 34 while the progressing cavity pump 10 is operating, to indicate to an operator on the ground that the progressing cavity pump 10 is operating. Preferably, the indicator 84 has a body 64 with a female threaded portion 74 at its bottom end 36, and a marker 86 attached to its top end 38. The threaded female portion 74 is preferably sized and shaped to threadingly connect to the threaded extension 68 of the polished rod 34. In this way, the indicator 84 may also serve a function of protecting the threaded extension 68 from the damaging effects of the environment. The marker 86, attached to the top end 38 of the body 64 of the indicator 84 may preferably be sized and shaped, and/or marked with a colour, pattern, symbol, or the like, that will visually convey to the operator on the ground information about the rotation of the polished rod 34, to allow the operator to determine whether the progressing cavity pump 10 is operating, or operating correctly, based on, for example the speed of rotation of the marker 86, or the smoothness of the rotation of the marker 86. By way of example, the marker 86 on the indicator 84 shown in FIG. 12 is a flat, oval-shaped plate, which when viewed from the ground would be seen as changing shape from a full oval shape when seen face on, to a thin line, when seen from its side, as the polished rod 42 rotates. No change in shape of the marker 86 would indicate to the operator on the ground that the marker 86 is stationary, and therefore the polished rod 34 is not rotating, meaning that the progressing cavity pump 10 is not operating. Similarly, the speed of rotation of the polished rod 34 can be judged by the operator based on the rate of change in the shape of the marker 86. Other shapes for the marker 86 are comprehended by the present invention, including circular, rectangular, square, triangular, as well as other polygonal shapes, and three-dimensional shapes, such as spheres, cylinders, cones, and the like.

[0059] It is contemplated that the polished rod 34 and/or the slider tool 72 may be provided as a kit for retrofitting a conventional progressing cavity pump, or for building a new progressing cavity pump 10 according to an embodiment of the present invention. Furthermore, the kit may include one or more of the polished rod clamp 42, the extended bolts 80, the extended nuts 80, and the indicator 84.

[0060] Having described preferred embodiments of the progressing cavity pump 10 above, a method of flushing out debris that has built up in the progressing cavity pump 10 is described next, by way of an example. According to an embodiment of the present invention one method of flushing the progressing cavity pump may follow substantially the following steps:

[0061] stopping the drive system 26;

[0062] engaging the rod backspin device (if equipped);

[0063] rigging up the flush-by/service rig to the progressing cavity pump 10;

[0064] removing the indicator 84 from the top end 38 of the polished rod 34 (if present);

[0065] connecting the threaded male portion 66 of the polished rod 34 to the flush-by/service rig;

[0066] raising the polished rod 34 up with the flush-by/service rig to free the rotor 52 from the stator 50;

[0067] flushing the production tubing 16 with a desired fluid (i.e. oil) to free debris build up in the stator 50;

[0068] disengaging the rod backspin device (if equipped);

[0069] lowering the polished rod 34 down with the flush-by/service rig to seat the polished rod claim 42 in the receiver at the top of the hollow drive shaft 40 of the transmission unit 30;

[0070] disconnecting the threaded male portion 66 of the polished rod 34 from the flush-by/service rig;

[0071] connecting the slider tool 72 to the top end 36 of the polished rod 34 via the threaded extension 68;

[0072] connecting the top end 36 of the slider tool 72 to the flush-by/service rig;

[0073] raising the slider tool 72 with the flush-by/service rig enough to enable removal of the polished rod clamp 42;

[0074] removing the polished rod clamp 42 from the polished rod 34;

[0075] lowering the slider tool 72 with the flush-by/service rig to lower the rotor until a reference point is reached (i.e. bottoming out the rotor in the stator, or hitting the top of the tag bar 56, as is known in the art);

[0076] raising the slider tool 72 with the flush-by/service rig by a predetermined space-out distance to align the rotor 52 within the stator 50;

[0077] installing polished rod clamp 42 onto the polished rod 34 to secure the rotor 52 at the correct depth when seated in the receiver at the top of the hollow drive shaft 40 of the transmission unit 30;

[0078] lowering the slider tool 72 with the flush-by/service rig to seat the polished rod clamp 42 in the receiver at the top of the hollow drive shaft 40;

[0079] disconnecting the top end 36 of the slider tool 72 from the flush-by/service rig;

[0080] disconnecting the slider tool 72 from the polished rod 34;

[0081] installing the indicator 84 to the top end 38 of the polished rod 34 (if desired);

[0082] filling the production tubing 16 with desired fluid (i.e. oil) and pressure testing the production tubing 16;

[0083] loading a desired fluid (i.e. oil) between the casing 18 and production tubing 16;

[0084] un-rigging and removing the flush-by/service rig from the progressing cavity pump 10; and

[0085] starting the drive system 26.

[0086] According to an embodiment of the present invention a method of checking and adjusting the depth of the rotor 52 in the progressing cavity pump 10 may follow substantially the same method as above, but without carrying out the step of flushing the production tubing 16 with a desired fluid (i.e. oil) to free debris build up in the stator 50.

[0087] As mentioned above, a conventional progressing cavity pump may also be retrofitted with a polished rod according to the present invention, to convert it into a progressing cavity pump 10 according to the present invention. By way of example, one such method may follow substantially the following steps:

[0088] stopping the drive system 26;

[0089] engaging the rod backspin device (if equipped);

[0090] rigging up the flush-by/service rig to the conventional progressing cavity pump;

[0091] removing the rod coupler 46 from the top end 38 of the conventional polished rod (if equipped);

[0092] connecting the threaded male portion 66 of the conventional polished rod 62 to the flush-by/service rig;

[0093] raising the conventional polished rod 62 upwardly with flush-by/service rig to free the rotor 52 from the stator 50;

[0094] flushing the production tubing 16 with a desired fluid (i.e. oil) to free debris build up in stator 50;

[0095] disengaging the rod backspin device (if equipped);

[0096] raising the conventional polished rod 62 up with flush-by/service rig until the limit of travel is reached when the rod coupler 46 impinges on the narrow passageway in piping tee 20;

[0097] unbolting the piping tee 20 from the production tubing 16;

[0098] lifting the above ground equipment, including the piping tee 20, the stuffing box 24, the transmission 30, the electric motor 28, and the belt and sheave reduction 32, together with the conventional polished rod 62, upwardly from the production tubing 16, with the flush-by/service rig, until the top of the sucker rod 44 is high enough above the production tubing 16;

[0099] removing the polished rod clamp 42 from the top end 38 of the conventional polished rod 62;

[0100] positioning a C-plate on the top of the production tubing 16, about the polished rod 34;

[0101] attaching the polished rod clamp 42 to the polished rod 34 above the C-plate, and lowering the polished rod 34 to seat the polished rod clamp 42 on the C-plate to support the rod string 44;

[0102] disconnecting the conventional polished rod 62 from the rod coupler 46;

[0103] sliding the disconnected conventional polished rod 62 up through the suspended above ground equipment, and removing it;

[0104] sliding a polished rod 34, according to an embodiment of the present invention, down through the suspended above ground equipment, and connecting the top end 38 of the polished rod 34 to the flush-by/service rig;

[0105] connecting the bottom end 36 of the polished rod 34 to the rod coupler 46;

[0106] raising the polished rod 34 high enough to unseat the polished rod clamp 42 from the C-plate, and removing the C-plate;

[0107] removing the polished rod clamp 42 from the polished rod 34 and attaching it to the top end 38 of the polished rod 34;

[0108] lowering the above ground equipment, including the piping tee 20, the stuffing box 24, the transmission 30, the electric motor 28, and the belt and sheave reduction 32, together with the polished rod 34, downwardly onto the production tubing 16, with the flush-by/service rig, until the piping tee 20 is seated on the production tubing 16;

[0109] bolting the piping tee 20 to the production tubing 16;

[0110] lowering the polished rod 34 with the flush-by/service rig to seat the polished rod clamp 42 in the receiver at the top of the hollow drive shaft 40;

[0111] disconnecting the top end 38 of the polished rod 34 from the flush-by/service rig;

[0112] installing the indicator 84 to the top end 38 of the polished rod 34 (if desired);

[0113] filling the production tubing 16 with desired fluid (i.e. oil) and pressure testing the production tubing 16;

[0114] loading a desired fluid (i.e. oil) between the casing 18 and production tubing 16;

[0115] un-rigging and removing the flush-by/service rig from the progressing cavity pump 10; and

[0116] starting the drive system 26.

[0117] It should be noted that the above method for replacing a conventional polished rod 62 in a conventional progressing cavity pump with a polished rod 34 according to the present invention, does not include steps for setting the rotor 52 to the correct depth. Preferably, however, the rotor 52 may be checked and adjusted using the slider tool 72, prior to the step of filling the production tubing 16 with desired fluid (i.e. oil) and pressure testing the production tubing 16, as described above.

[0118] While reference has been made to various preferred embodiments of the invention other variations, implementations, modifications, alterations and embodiments are comprehended by the broad scope of the appended claims. Some of these have been discussed in detail in this specification and others will be apparent to those skilled in the art. Those of ordinary skill in the art having access to the teachings herein will recognize these additional variations, implementations, modifications, alterations and embodiments, all of which are within the scope of the present invention, which invention is limited only by the appended claims.

Claims

1. A polished rod for suspending a rod string in a production tubing of a progressing cavity pump, said polished rod comprising: an elongate body defining a first end and a second end; a threaded connector at said first end, said first threaded connector being positioned coaxially inward of said elongate body, and having a diameter less than a diameter of said elongate body; a second threaded male portion positioned on said elongate body at said second end, said second threaded male portion being configured to connect to a second rod string component; and a shoulder on said first end between said diameter of said elongate body and said diameter of said threaded connector.

2. The polished rod as claimed in claim 1, further comprising a first threaded male portion positioned on said elongate body at said first end, said first threaded male portion being configured to connect to a first rod string component.

3. The polished rod as claimed in claim 1, wherein said threaded connector extends from said first end.

4. The polished rod as claimed in claim 1, wherein said threaded connector recedes into said first end.

5. The polished rod as claimed in claim 1, wherein said elongate body is cylindrical.

6. The polished rod as claimed in claim 1, wherein said elongate body has a standard polished rod length.

7. The polished rod as claimed in claim 6, wherein said standard polished rod length is from about 6 feet to about 60 feet, inclusive.

8. The polished rod as claimed in claim 1, wherein said first or second string component is a rod coupler, a sucker rod, or an endless rod reel.

9. The polished rod as claimed in claim 1, wherein said diameter of said threaded connector is from about 3/4 inch to about 2 and 1/2 inches, inclusive.

10. The polished rod as claimed in claim 1, wherein said diameter of said second threaded male portion is from about 1/2 inch to about 1 and 1/2 inches, inclusive.

11. A progressing cavity pump comprising: said polished rod defined by claim 1; said rod string suspended from said polished rod in said production tubing; said rod string including a rotor; and said production tubing including a stator.

12. A method of making the progressing cavity pump of claim 11, the method comprising the steps of: providing a conventional progressing cavity pump having a conventional polished rod; and replacing said conventional polished rod with said polished rod defined in claim 1.

13. An indicator for use with a polished rod installed in a progressing cavity pump, said indicator comprising: a body defining two ends; a connector attached to one of said two ends, said connector being sized and shaped to removably attach to a free end of said polished rod; and a marker attached to the other of said two ends; wherein when attached to said one end of said polished rod, said connector helps to protect said one end from damaging effects of the environment, and said marker indicates to an operator whether the progressing cavity pump is operating.

14. The indicator as claimed in claim 13, wherein said connector is sized and shaped to connect to said threaded connector of said polished rod defined in claim 1.

15. The indicator as claimed in claim 13, wherein said marker has a polygonal shape, or a three-dimensional shape.

16. The indicator as claimed in claim 15, wherein said marker has a circular shape, a rectangular shape, a square shape, a triangular shape, a polygonal shape, a spherical shape, a cylindrical shape, or a conical shape.

17. A slider tool for use with said polished rod defined in claim 1, said slider tool comprising: an elongate body defining a first end and a second end, said first end being sized and shaped to be gripped by, held by, or attached to, above ground equipment of said progressing cavity pump; a threaded connector at said second end, said threaded connector of said slider tool being positioned coaxially inward of said elongate body of said slider tool, and having a diameter less than a diameter of said elongate body of said slider tool; a shoulder on said first end between said diameter of said elongate body of said slider tool and said diameter of said threaded connector of said slider tool; wherein said threaded connector of said slider tool is adapted to threadingly engage said threaded connector of said polished rod; and wherein said slider tool permits an operator to lower said polished rod in said production tubing without disassembling said above ground equipment.

18. The slider tool as claimed in claim 17, wherein said elongate body of said slider tool has a diameter that is equal to or less than said diameter of said polished rod.

19. The slider tool as claimed in claim 17, wherein said threaded connector of said slider tool extends from said second end of said slider tool.

20. The slider tool as claimed in claim 17, wherein said threaded connector of said slider tool recedes into said second end of said slider tool.

21. The slider tool as claimed in claim 17, wherein said threaded connector of said slider tool and said threaded connector of said polished rod are adapted to form a connection that is sized and shaped to pass through a stuffing box of said progressing cavity pump.

22. The slider tool as claimed in claim 17, wherein when said threaded connector of said slider tool threadingly engages said threaded connector of said polished rod, said shoulder of said slider tool abuts said shoulder of said polished rod.

23. The slider tool as claimed in claim 17, wherein said first end is sized and shaped to be gripped by, held by, or attached to, a flush-by or service rig.

24. A polished rod clamp comprising: a pair of clamp members adapted to clamp a polished rod therebetween, each said clamp member having at least two apertures; at least two bolts, each said bolt being adapted to pass through said apertures from one of said pair of clamp members to the other of said pair of clamp members; and at least two extended nuts, each said extended nut being adapted to secure to one of said at least two bolts, to clamp said polished rod between said pair of clamp members; wherein each of said at least two extended nuts has a length greater than a conventional nut, causing said at least two extended nuts to project out from a side of said clamp member by an increased distance to facilitate installation and removal of said polished clamp by a user with conventional tools in the field.

25. The polished rod clamp as claimed in claim 24, wherein said at least two extended nuts each have a length in a range of about 3/4 inch to about 1 and 1/2 inches, inclusive.

26. A kit comprising: said polished rod defined in claim 1; and said slider tool defined in claim 17.

27. The kit according to claim 26, further comprising at least one of the polished rod clamp as defined in claim 24 and the indicator as defined in claim 13.

28. A method of making the polished rod defined in claim 1, said method comprising the steps of: providing a conventional polished rod having an elongate body having two ends; and machining one end of said conventional polished rod to form said threaded connector at said one end, said threaded connector being positioned coaxially inward of said elongate body of said conventional polished rod, and having a diameter less than a diameter of said elongate body of said conventional polished rod.

29. The method as claimed in claim 28, wherein said machining step forms said threaded connector to extend from said one end.

30. The method as claimed in claim 28, wherein said machining step forms said threaded connector to recede into said one end.

31. A method of checking or setting a depth of said rotor of the progressing cavity pump of claim 11, said method comprising the steps of: providing said slider tool as defined in claim 17; connecting said threaded connector of said slider tool to said threaded connector of said polished rod; connecting said first end of said slider tool to said flush-by or service rig; raising said slider tool with said flush-by or service rig enough to unseat, and enable removal of, a polished rod clamp attached to said polished rod; removing said polished rod clamp from said polished rod; lowering said slider tool with said flush-by or service rig until said rotor reaches a reference point; raising said slider tool with said flush-by or service rig by a predetermined space-out distance; installing said polished rod clamp on said polished rod; lowering said slider tool with said flush-by or service rig to seat said polished rod clamp; and disconnecting said slider tool from said polished rod.

32. A method of flushing the progressing cavity pump of claim 11, said method comprising the steps of: providing said slider tool as defined in claim 17; connecting said threaded connector of said slider tool to said threaded connector of said polished rod; connecting said first end of said slider tool to said flush-by or service rig; raising said slider tool with said flush-by or service rig to free said rotor from said stator; flushing said production tubing with a desired fluid to fee debris build up in said stator; lowering said slider tool with said flush-by or service rig to seat a polished rod clamp attached to said polished rod; and disconnecting said slider tool from said polished rod.

33. A method of retrofitting a conventional progressing cavity pump having a conventional polished rod, said method comprising the steps of: connecting said conventional polished rod to a flush-by or service rig; raising said conventional polished rod with said flush-by or service rig towards limit of travel imposed by above ground equipment; disassembling above ground equipment to free said conventional polished rod from said production tubing to enable its removal from said conventional progressing cavity pump; disconnecting said conventional polished rod from said rod string and removing said conventional polished rod from said conventional progressing cavity pump; connecting said polished rod as defined in claim 1 to said rod string; reassembling said above ground equipment; and lowering said polished rod in said production tubing with said flush-by or service rig.