Polish rod leveling assembly

Abstract

A leveling assembly that is capable of lubrication without separating the individual leveling plates. The leveling assembly comprising: a first plate having a convex curved surface having a curvature, the first plate defining a central bore therethrough; a second plate having a concave curved surface shaped to mate with the convex curved surface; the second plate defining a central bore therethrough. One of the first or second plates defines a lubrication passageway extending from a first opening on an exterior surface thereof to a second opening on the curved surface, and a lubrication groove extending from the second opening to the central bore of the plate with the lubrication passageway.

Claims

1. A polish rod leveling assembly comprising: a first plate having a convex curved surface and a generally circular outer peripheral surface, the first plate defining a central bore therethrough with a first diameter; a second plate having a concave curved surface engaged with the convex curved surface, the second plate having a generally circular outer peripheral surface and a central bore therethrough with a second diameter; one of the first or second plates defining a lubrication passageway extending radially inwardly from a first opening on the circular outer peripheral surface thereof and communicated with a second opening on the curved surface of the plate with the lubrication passageway, the curved surface of the plate with the lubrication passageway having a lubrication groove defined thereon connected to and extending from the second opening.

2. The leveling assembly of claim 1, the lubrication groove having a lubrication exit groove extending therefrom, the lubrication exit groove communicating the lubrication groove with the central bore of the plate in which the lubrication passageway is defined.

3. The leveling assembly of claim 1, the lubrication groove having a lubrication exit groove extending therefrom, the lubrication exit groove communicating the lubrication groove with the circular outer peripheral surface of the plate in which the lubrication passageway is defined.

4. The leveling assembly of claim 1, further comprising a polish rod extending through the central bores of the first and second plates.

5. The leveling assembly of claim 1, the lubrication passageway and lubrication groove being defined on the first plate.

6. The leveling assembly of claim 1, further comprising a carrier bar positioned below and supporting the first and second plates.

7. A leveling assembly comprising: a first plate having a convex curved surface and a generally circular outer peripheral surface, the first plate defining a central bore therethrough with a first diameter; a second plate having a concave curved surface shaped to mate with the convex curved surface, the second plate having a generally circular outer peripheral surface and defining a central bore therethrough with a second diameter, one of the first or second plates defining a lubrication passageway extending radially inwardly from a first opening on a circular outer peripheral surface thereof and communicated with a second opening on the curved surface of the plate having the lubrication passageway, the curved surface of the plate with the lubrication passageway having a lubrication groove defined thereon connected to and extending from the second opening; a carrier bar positioned below and supporting the first and second plates, the carrier bar defining a central bore therethrough; and a polish rod passing through the central bore of the carrier bar and the central bores of the first plate and the second plate.

8. The leveling assembly of claim 7, the lubrication groove having a lubrication exit groove extending therefrom, the lubrication exit groove communicating the lubrication groove with the central bore of the plate in which the lubrication passageway is defined.

9. The leveling assembly of claim 7, the lubrication groove having a lubrication exit groove extending therefrom, the lubrication exit groove communicating the lubrication groove with the circular outer peripheral surface of the plate in which the lubrication passageway is defined.

10. The leveling assembly of claim 7, the first plate and the second plate having substantially the same thickness at an outer periphery thereof.

11. The leveling assembly of claim 7, the lubrication passageway and lubrication groove being defined on the first plate.

12. The leveling assembly of claim 7, a lubrication fitting being installed into the first opening.

13. The leveling assembly of claim 12, further comprising a spacer positioned between the first and second plates and the carrier bar.

14. The leveling assembly of claim 7, further comprising a load cell defining a central bore therethrough and supported by the first and second plates, the polish rod passing through the central bore of the load cell.

15. A polish rod leveling assembly for use with a pump jack comprising: a first plate having a convex curved surface and a generally circular outer peripheral surface, the first plate defining a central bore therethrough with a first diameter; a second plate having a concave curved surface engaged with the convex curved surface of the first plate, the second plate having a generally circular outer peripheral surface and a central bore therethrough with a second diameter; one of the first or second plates defining a lubrication passageway extending radially inwardly from a first opening on the circular outer peripheral surface thereof and communicated with a second opening on the curved surface of the plate with the lubrication passageway, the curved surface of the plate with the lubrication passageway having a lubrication groove defined thereon connected to and extending from the second opening; and a load cell supported by the first and second plates.

16. The leveling assembly of claim 15, the lubrication groove having a lubrication exit groove extending therefrom, the lubrication exit groove communicating the lubrication groove with the central bore of the plate in which the lubrication passageway is defined.

17. The leveling assembly of claim 15, further comprising a polish rod extending from the pump jack and passing through the openings in the first and second plates and through an opening in the load cell.

18. The leveling assembly of claim 17, further comprising a carrier bar positioned below and supporting the first and second plates.

19. The leveling assembly of claim 18, further comprising a spacer positioned between the carrier bar and the first and second plates.

20. The leveling assembly of claim 15, the lubrication passageway being defined in the first plate and the lubrication groove being defined on the curved surface of the first plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings included with this application illustrate certain aspects of the embodiments described. However, the drawings should not be viewed as illustrating exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art with the benefit of this disclosure.

(2) FIG. 1 is a perspective view of a conventional pump jack for reciprocating the sucker rod string of a downhole pump;

(3) FIG. 2 is a detail view of a cable bridle with one embodiment of a leveling assembly supporting a load cell, mounted to the polish rod, and supported by a spacer and carrier bar;

(4) FIG. 3 is a side view of one embodiment of the leveling assembly as mated in use, showing the leveling plates aligned and stacked together;

(5) FIG. 4 is a side view of one embodiment of the leveling assembly separated showing each leveling plate aligned with the other and separated;

(6) FIG. 5 is a top view of one embodiment of a plate having a convex curved surface;

(7) FIG. 6 is a top view of one embodiment of a plate having a concave curved surface;

(8) FIG. 7 is a cross-section view of one embodiment of a plate having a convex curved surface; and

(9) FIG. 8 is a cross-section view of one embodiment of a plate having a concave curved surface.

DETAILED DESCRIPTION

(10) The present disclosure may be understood more readily by reference to this detailed description. Numerous specific details are set forth in order to provide a thorough understanding of the various embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

(11) As used herein and in the appended claims, a component or method that “comprises” or “includes” one or more specified parts means that the component or method includes the specified parts alone, or includes the specified parts together with one or more additional parts.

(12) As used herein and in the appended claims, a component or method “comprising” or “including” one or more specified steps or parts means that the component or method includes the specified steps or parts alone, or includes the specified steps or parts together with one or more additional steps or parts.

(13) Referring now to FIG. 1, a pump jack 10 is shown driving a reciprocating pump (not shown) located downhole in the bore of a subterranean oil well. The pump jack assembly 10 includes a gearbox 20 powered by a motor (not shown). The gearbox 20 is used to turn a crank and counter weight 30. The crank and counter weight 30 is connected to walking beam 40 by a pitman arm 50. Walking beam 40 is supported by Sampson posts 80. A horsehead 70, located at one end of a walking beam 40, delivers the reciprocal pumping stroke to the pump (not shown). A cable bridle assembly shown in FIG. 2 is suspended from cables 60a, 60b which roll tangentially over the horsehead 70 as it reciprocates. A carrier bar 140 is hung from the end of the cable bridle 60. A string of sucker rods (not shown) and polish rod 100 are suspended from the carrier bar 140. The sucker rods (not shown) extend down the production tubing (not shown) to drive the subterranean pump (not shown).

(14) Referring to FIG. 2, a detailed view of a cable bridle 60 incorporating one embodiment of the leveling assembly 90 mounted to a polish rod 100 is shown. A polish rod 100 is connected to the top of the sucker rods (not shown). The polish rod 100 extends upwardly through a stuffing box seal (not shown) and through a bore in the carrier bar 140. A polish rod clamp 110 is secured to the polish rod 100 above the carrier bar 140. The weight of the polish rod 100 is borne by the polish rod clamp 110, which bears against the carrier bar 140 through a load cell 120, a leveling assembly 90, and spacer 130.

(15) Cable bridle 60 and carrier bar 140 connect the polish rod 100 using the polish rod clamp 110 to the horsehead 70, which is connected to the walking beam 40. Load cell 120 is held in place on polish rod 100 by the polish rod clamp 110 on top, and is supported by leveling assembly 90 on the bottom. The polish rod 100 passes through the load cell 120. Handle 125 attaches to one of the cables 60a to prevent rotation of load cell 120 relative to the polish rod 100. Wiring 127 carries signals from load cell 120 to the well controller (not shown) or other data collection or controlling device (not shown).

(16) The load cell 120 shown in FIGS. 1 and 2, converts the load acting on it into electrical signals. The load cell may for example comprise strain gauges attached, bonded, or otherwise connected onto a beam or structural member that deforms when weight is applied.

(17) Most applications for load sensors or weight sensors using strain gauges have a straight forward mechanism for applying the load to the weight sensor. Typical weight sensors have a plate or pad on which the item being weighed can be placed; however, some applications, such as measuring the load on a polish rod 100 are more problematic due to the shifting load. As described in FIG. 1, the pump jack 10 uses the polish rod 100 to operate a pump in the well. As a result the polish rod 100 is continually placed under tension and compression loads as it moves through the pumping cycle. Control applications for the well require a measurement of the load being placed on the polish rod 100 during the pumping cycle. This load is measured during the pumping stroke by the load cell 120.

(18) The leveling plates in current leveling assemblies, which are frequently used to support load cells, may corrode, or oxidize, between the individual leveling plates. The corrosion, or oxidation, creates friction and binding between the mating surfaces of the leveling plates and restricts the ability of the leveling assembly to compensate for alignment variations. The alignment variations if uncorrected can cause the load cell 120 to incorrectly report loads sensed, and can also cause the polish rod to score and fail. The current leveling assembly maintenance requires significant effort and creates unnecessary risk of a costly reclamation effort, which could cause operators to neglect lubricating between the leveling plates.

(19) Referring now to FIGS. 3 and 4, one embodiment of the leveling assembly 90 according to the concepts described herein is shown. FIG. 3 is a side view of the leveling assembly 90 with first and second plates 150 and 170 aligned and stacked together (mated). FIG. 4 is a side view of the leveling assembly 90 with plates 150 and 170 aligned but separated (un-mated). The embodiment of FIGS. 3 and 4 includes first plate 150 having a convex curved surface 200, the first plate 150 defining a central bore 160 therethrough with a first diameter D1. The first plate also has a first height, or outer diameter thickness, H1. In other words plate 150 has a thickness H1 at an outer periphery thereof. Also included is a second plate 170 having a concave curved surface 210 shaped to mate with the convex curved surface 200. The second plate also defines a central bore 180 therethrough with a second diameter D2. The second plate has a second height, or outer diameter thickness, H2. In other words plate 170 has a thickness H2 at an outer periphery thereof. D1 and D2 as shown here are substantially similar in size, but each can be varied if desired. One example of when D1 and D2 might be different is when using a protective sleeve for the polish rod 100. In this case, the plate on top will have a larger diameter bore than that of the bottom plate. This would allow the lip of the sleeve to fit within the upper bore, while the lower bore would act as a base for the sleeve to rest on. Likewise, H1 and H2 as shown here are substantially similar in size, but each can be varied if desired.

(20) Although not shown in FIGS. 3 and 4, the polish rod 100 passes through the central bore 160 of first plate 150 and through the central bore 180 of second plate 170. This configuration is depicted in FIGS. 1 and 2. Also not shown in FIGS. 3 and 4 are the lubrication passageways; however, lubrication passageway 250 in the first plate 150, and lubrication passageway 255 in the second plate 170 are illustrated in FIGS. 7 and 8. The illustrations above were not shown for clarity.

(21) There is no default orientation for the first plate 150 and second plate 170 other than the convex curved surface 200 should face (mate with) the concave curved surface 210. Meaning, either the first plate 150 or the second plate 170 can be on top relative to the carrier bar 140 or spacer 130, but the plates should be mated together so that the convex curved surface 200 of the first plate 150 fits against the concave curved surface 210 of the second plate 170. Some applications may dictate an orientation, such as mentioned above with the sleeve, but absent such a need the leveling assembly 90 will work in either orientation. In the embodiment shown plate 150 is the upper plate.

(22) Referring now to FIGS. 5 and 6, one embodiment of the leveling assembly 90 according to the concepts described herein is shown. FIG. 5 shows a view of the curved surface 200 of the first plate. A lubrication fitting 190, which may be for example a zerk fitting is installed into a first opening 260 defined in the outer surface 152 at the periphery thereof. A lubrication passageway 250 (shown in FIG. 7) extends from first opening 260 to a second opening 220 located on convex surface 200. A lubrication groove 230 extends from opening 220. In one embodiment the lubrication groove 230 includes a lubrication exit groove 230a which extends to the central bore 160. In an alternative embodiment the lubrication groove may include a lubrication exit 230b (shown in phantom lines) which extends to outer surface 152.

(23) FIG. 6 shows a view of the second plate 170 with its concave curved surface 210 facing upward. The phantom lines shown in FIG. 6 demonstrate that in an embodiment of a leveling assembly the leveling plate with the concave surface may include a lubrication passageway and lubrication groove as well. It is understood that typically only one of the first and second plates 150 and 170 in a leveling assembly will include such features. In the alternative embodiment of FIG. 6 a lubrication fitting 195, such as a zerk fitting is installed into a first opening 265 on the outer surface 172. A lubrication passageway 255 (shown in FIG. 8) extends from first opening 265 to a second opening 225 on concave curved surface 210. A lubrication groove 235 which includes a lubrication exit groove 235a is defined in concave surface 210 and connected to lubrication passageway 255 via second opening 225. Exit groove 235a extends to central bore 180. An alternate exit groove 235b is shown extending to outer surface 172 on second plate 170. Lubrication groove 235 may include one or both of exit grooves 235a and 235b. Either or both of plates 150 and 170 may have lubrication grooves and passageways as described herein.

(24) FIGS. 7 and 8 depict cross sections of leveling plates 150 and 170. FIG. 7 shows a cross-section view of the first plate 150. Lubrication fitting 190, which may be a zerk fitting, can be seen installed into the lubrication passageway 250. The lubrication passageway extends from the first opening 260 to the second opening 220. FIG. 8 shows a cross-section view of the second plate 170. The phantom lines in FIG. 8 depict the embodiment where plate 170 includes lubrication passageway 255 and lubrication groove 235.

(25) As depicted in FIGS. 1 and 2, the leveling assembly 90, comprising leveling plates 150 and 170 is supported by carrier bar 140. A spacer 130 is positioned between leveling plates 150 and 170 and carrier bar 140. Although in the disclosed embodiment a spacer is used, it is understood that the leveling assembly 90 may be positioned directly on carrier bar 140.

(26) The curvature of the plates 200, 210 should have substantially similar, but complementary radii. The convex surface 200 and the concave surface 210 should fit together (mate) with only minor gaps therebetween (aside from the lubrication grooves and holes). The similarity of radius (or fit) allows for the plates to better spread the force across the full mating (curved) surfaces of the two plates.

(27) The lubrication groove should be created in such a way as to not prevent the plates from sliding relative to each other. The plates need to retain the ability to adjust for misalignments. Referring to the embodiment in which the lubrication groove is in first plate 150, lubrication groove 230 can be a variation in the surface that creates a space between the convex surface 200 and concave curved surface 210 sufficient to allow a lubricant to flow therethrough.

(28) Exit groove 230a provides a lubricant between plates 150 and 170, and because the exit is to the central bore 160 may also provide lubrication to the polish rod 100 where it passes through central bores 160 of plate 150. This can reduce friction, and possibly wear.

(29) Therefore, the present method and system are well adapted to attain the ends and advantages mentioned, as well as those that are inherent therein. The particular examples disclosed above are illustrative only, because the present method and system may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the present method and system. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.