COUNTERWEIGHTED PUMPJACK WITH REVERSIBLE MOTORS

Abstract

A counterweighted well pumping unit comprises two or more reversible motors, each of which is directly and operatively connected to a rotatable drive component mounted on a support structure positioned over a wellhead. For each motor, an elongate, flexible drive element is trained over the associated rotatable drive component, with one end of the flexible drive element connected to a counterweight assembly and the other end connected to a pump rod string associated with the wellhead. Actuation of the motors rotates the rotatable drive components, thus causing the drive elements to move the pump rod string and the counterweight assembly in opposite vertical directions. The rotational direction of the drive motors is alternated so as to alternate the directions of vertical movement of the pump rod string and the counterweight. The counterweight assembly may be concentric with or offset from the wellhead.

Claims

1. A well pumping unit comprising: (a) a platform supported by a support structure; (b) two or more reversible drive motors mounted on the platform, with each reversible drive motor having a rotating drive shaft operatively connected to an associated rotatable drive component such that actuation of the drive motor will cause the associated rotatable drive component to rotate at the same rate as the drive shaft; (c) in association with each reversible drive motor, an elongate flexible drive element having a first end and a second end, said flexible drive element being tractively engageable with the associated rotatable drive component, and said flexible drive element being trained over and tractively engaging the associated rotatable drive component such that: c.1 the first end of the flexible drive element extends below the platform and is connected to a counterweight assembly; and c.2 the second end of the flexible drive element extends below the platform and is adapted for connection to a pump rod string; c.3 rotation of all of the two or more reversible drive motors in a first cooperative sense will raise the first ends of all of the flexible drive elements; and c.4 rotation of all of the two or more reversible drive motors in a second cooperative sense opposite to said first cooperative sense will raise the second ends of all of the flexible drive elements; and (d) a power and control system for regulating the operation of the reversible drive motors.

2. A well pumping unit as in claim 1 wherein the second ends of all flexible drive elements are connected to a pump rod string associated with a wellhead.

3. A well pumping unit as in claim 2 wherein the rotatable drive components associated with the two or more reversible drive motors are arranged on the platform such that the elongate flexible drive elements will carry equal percentages of the weight of the counterweight assembly, and will carry equal percentages of the total weight of the pump rod string and loads carried thereby.

4. A well pumping unit as in claim 2 wherein: (a) the pump rod string extends from the wellhead in a vertical orientation; (b) the counterweight assembly defines a vertical passage through which the second ends of the flexible drive elements extend for connection to the pump rod string; and (c) the center of gravity of the counterweight is concentric with the pump rod string.

5. A well pumping unit as in claim 2 wherein the pump rod string extends from the wellhead in a non-vertical orientation.

6. A well pumping unit as in claim 2 wherein: (a) the pump rod string extends from the wellhead in a vertical orientation; and (b) the counterweight assembly is laterally offset from the pump rod string.

7. A well pumping unit as in claim 1 wherein at least one of the two or more reversible drive motors is a hydraulic motor.

8. A well pumping unit as in claim 1 wherein one of the rotatable drive components comprises a drive sprocket, and wherein the flexible drive element associated with said drive sprocket comprises a drive chain.

9. A well pumping unit as in claim 1 wherein one of the rotatable drive components comprises a drive sheave, and wherein the flexible drive element associated with said drive sheave comprises a drive belt.

10. A well pumping unit as in claim 9 wherein the drive belt comprises a synchronous belt and the drive sheave comprises a synchronous belt pulley.

11. A well pumping unit as in claim 1, further comprising polish rod lockout means.

12. A well pumping unit as in claim 1, further comprising counterweight lockout means.

13. A well pumping unit comprising: (a) a platform supported by a support structure; (b) two or more reversible drive motors mounted on the platform, with each reversible drive motor having a rotating drive shaft coupled to an associated rotatable drive component in a direct drive arrangement, such that actuation of the drive motor will cause the associated rotatable drive component to rotate at the same rate as the drive shaft; (c) in association with each reversible drive motor, an elongate flexible drive element having a first end and a second end, said flexible drive element being tractively engageable with the associated rotatable drive component, and said flexible drive element being trained over and tractively engaging the associated rotatable drive component such that: c.1 the first end of each flexible drive element extends below the platform and is connected to a counterweight assembly; and c.2 the second end of each flexible drive element extends below the platform and is directly connected to a pump rod associated with a wellhead, wherein the direct connection between the second end of the flexible drive element and the pump rod is made via rod engagement means without any component having a non-pump-rod-connection-related function intervening between the flexible drive element and the pump rod; c.3 rotation of all of the two or more reversible drive motors in a first cooperative sense will raise the first ends of all of the flexible drive elements and in turn will raise the counterweight; and c.4 rotation of all of the two or more reversible drive motors in a second cooperative sense opposite to said first cooperative sense will raise the second ends of all of the flexible drive elements and in turn will raise the pump rod; and (d) a power and control system for regulating the operation of the reversible drive motors.

14. A well pumping unit as in claim 13 wherein the rotatable drive components associated with the two or more reversible drive motors are arranged on the platform such that the flexible drive elements will carry equal percentages of the weight of the counterweight assembly, and will carry equal percentages of the total weight of the pump rod and loads carried thereby.

15. A well pumping unit as in claim 13 wherein: (a) the pump rod extends from the wellhead in a vertical orientation; (b) the counterweight assembly defines a vertical passage through which the second ends of the flexible drive elements extend for connection to the pump rod; and (c) the center of gravity of the counterweight is concentric with the pump rod.

16. A well pumping unit as in claim 13 wherein the pump rod extends from the wellhead in a non-vertical orientation.

17. A well pumping unit as in claim 13 wherein: (a) the pump rod extends from the wellhead in a vertical orientation; and (b) the counterweight assembly is laterally offset from the pump rod.

18. A well pumping unit as in claim 13 wherein at least one of the two or more reversible drive motors is a hydraulic motor.

19. A well pumping unit as in claim 13 wherein one of the rotatable drive components comprises a drive sprocket, and wherein the flexible drive element associated with said drive sprocket comprises a drive chain.

20. A well pumping unit as in claim 13 wherein one of the rotatable drive components comprises a drive sheave, and wherein the flexible drive element associated with said drive sheave comprises a drive belt.

Description

BRIEF SUMMARY OF THE DRAWINGS

[0030] Embodiments in accordance with the present disclosure will now be described with reference to the accompanying Figures, in which numerical references denote like parts, and in which:

[0031] FIG. 1 is an elevational perspective view of a first embodiment of a counterweighted pump jack, shown with the counterweight assembly in a raised position, and with the pump rod string near the bottom of its downstroke.

[0032] FIG. 2 is a top view of a counterweighted pump jack as in FIG. 1, showing multiple drive motors attached to bearing blocks and drive sheaves via drive shafts.

[0033] FIG. 3 is an oblique top view of the equipment platform of a counterweighted pump jack as in FIG. 1, shown with exemplary embodiments of counterweight lockout means and rod string lockout means installed.

[0034] FIG. 4 is a perspective view of a second embodiment of a counterweighted pump jack in accordance with the present disclosure.

[0035] FIG. 5 is a perspective view of a third embodiment of a counterweighted pump jack adapted for operation in association with an angled wellbore.

[0036] FIG. 6 is a perspective view of a pump jack similar to the pump jack shown in FIG. 5, but with an alternative embodiment of the drive system.

[0037] FIG. 7 is a perspective view of a fourth embodiment of a counterweighted pump jack in which the counterweight is laterally offset from the wellbore in association with which the pump jack has been installed, shown with the counterweight assembly in a raised position, and with the rod string near the bottom of its downstroke.

DETAILED DESCRIPTION

[0038] FIGS. 1-3 illustrate a first embodiment 100 of a well pumping unit in accordance with the present disclosure. Pumping unit 100 comprises a support structure 120 that may be positioned over a wellhead 10 associated with a wellbore. Wellhead 10 will typically include a stuffing box 12 through which and upward from which extends a polished rod 15 associated with a pump rod string connected to a downhole pump (not shown) disposed within a production tubing string installed in the wellbore. Wellhead 10 also includes a flow tee 14 for drawing off fluids produced from the well.

[0039] In FIGS. 1-3, support structure 120 is shown as comprising a plurality of vertical columns 20, with a perimeter support member 25 connecting columns 20 at about mid-height. This depiction is solely for conceptual illustrative purposes; the configuration of support structure 120 for a given application will be a matter of design choice, and embodiments of well pumping units in accordance with the present disclosure are not limited to support structures as shown in any illustrated embodiment or to support structures of any other particular configuration.

[0040] An equipment platform 30 is provided at the top of or in an upper region of support structure 120. In FIGS. 1-3, platform 30 is shown as a generally solid platform (with openings as needed for functional purposes described later herein), but this is by way of non-limiting example only. In alternative embodiments, platform 30 could have an open-grated surface or could comprise an open structure.

[0041] As most clearly shown in FIG. 2, a plurality of drive motors 70, each having an output drive shaft 72, are mounted on platform 30 in a generally symmetrical pattern around a central opening 32 provided in platform 30 for passage of polished rod 15. Each drive shaft 72 operatively engages a rotatable drive component 80 (shown in the Figures in the form of a drive sheave) in association with a pair of suitable bearings 82. Trained in operative engagement over each rotatable drive component 80 is an elongate flexible drive element 60 (shown in the Figures in the form of a drive belt) having a first end 60C and a second end 60R, both of which extend downward on either side of the associated rotatable drive component 80 through a secondary opening or openings 35 in platform 30.

[0042] As best seen in FIG. 1, the first ends 60C of all flexible drive elements 60 are connected to a counterweight assembly 50 by means of suitable counterweight connection components 54. In the embodiment shown in FIG. 1, counterweight assembly 50 comprises a cradle structure 51 of generally toroidal configuration with a central vertical opening 55. Cradle 51 is configured to receive removable arcuate counterweight plates 52, and is disposed within support structure 120 so as to be vertically movable therewithin. Also shown is vertical guide means (shown in the form of guide rollers 56 engageable with columns 20) for guiding the vertical movement of counterweight assembly 50 within support structure 120. This illustrated configuration of counterweight assembly 50 is by way of non-limiting example only, and counterweight assembly 50 can be provided in alternative configurations to suit specific operational requirements.

[0043] Also as seen in FIG. 1, the second ends 60R of all flexible drive elements 60 are extended downward through central opening 55 in counterweight cradle 51, and are connected to a rod engagement member 40 by means of suitable rod clamp connection components 42. Rod engagement member 40 securely engages polished rod 15 by means of a suitable polished rod clamp or clamps 44.

[0044] It can thus be seen that actuation of all drive motors 70 in a first cooperative sense will cause counterweight assembly 50 to be lifted (while rod engagement member 40 and the associated rod string move downward), and that actuation of all drive motors 70 in a second cooperative sense (opposite to the first cooperative sense) will cause rod engagement member 40 and the associated rod string to be lifted (while counterweight assembly 50 moves downward).

[0045] A power and control system (conceptually illustrated in FIG. 1 and indicated by reference number 110) is provided for actuating drive motors 70. Strictly speaking, drive motors 70 form part of power and control system 110, but for purposes of the present discussion, power and control system 110 is considered as comprising means for actuating drive motors 70 and for controlling their operative functions. In preferred embodiments of pumping units in accordance with the present disclosure, drive motors 70 will comprise hydraulic drive motors, and in such embodiments power and control system 110 will comprise one or more prime movers (not shown) actuating one or more hydraulic pumps that circulate hydraulic fluid to and from drive motors 70 by means of suitable hydraulic lines (indicated conceptually in FIG. 1 by reference number 115).

[0046] FIG. 3 illustrates pumping unit 100 with the upper end of polished rod 15 extending above platform 30, with suitable polished rod lockout clamps 46 installed as a safety precaution to prevent vertical movement of the pump rod string during service and maintenance operations. For similar purposes, suitable counterweight lockout means (illustrated by way of example as structural beams 90 supported on perimeter support member 25) are shown installed to prevent downward movement of counterweight assembly 50 during service and maintenance operations.

[0047] FIG. 4 illustrates a second embodiment 200 of a pumping unit in accordance with the present disclosure. Pumping unit 200 differs from pumping unit 100 in FIGS. 1-3 only in that pumping unit 200 is shown with a support structure 210 having square columns 220, a square equipment platform 230, a square counterweight assembly 250 with L-shaped counterweight plates 252, and an alternative layout of drive motors 70. Operationally, pumping unit 200 is essentially the same as pumping unit 100.

[0048] FIG. 5 illustrates a third embodiment 300 of a pumping unit in accordance with the present disclosure, adapted for use with slanted wells. Pumping unit 300 has vertical columns 320 and inclined columns 325 supporting an equipment platform 330, with drive motors 70 arranged (by way of non-limiting example) similar to the layout in FIG. 4. The counterweight assembly 350 in FIG. 5 is similar to the counterweight assembly 250 shown in FIG. 4, but modified to avoid interference with the sloped portions of flexible drive elements 60 that connect to rod engagement member 40 engaging polished rod 15 projecting from the inclined wellhead 10.

[0049] FIG. 6 illustrates an alternative layout for drive motors 70, shown in the context of pumping unit 300 for a slanted well as in FIG. 5. In this layout, there are four flexible drive elements 60 as in the other illustrated embodiments, but only two drive motors 70, each of which has an extended drive shaft 72E to engage two rotatable drive components 80. Although illustrated in association with slant-well pumping unit 300, this and similar drive motor layouts could of course be used with other pumping unit embodiments.

[0050] FIG. 7 illustrates a fourth embodiment 400 of a pumping unit in accordance with the present disclosure, having a counterweight assembly 450 that is laterally offset from wellhead 10. Pumping unit 400 has a support structure 420 with columns 425, a first cantilevered platform 430C carrying drive motors 70C associated with counterweight assembly 450, and a second cantilevered platform 430R carrying drive motors 70R associated with polished rod 15. In the illustrated embodiment, intermediate connectors 65 are provided for splicing flexible drive elements 60, but such connectors are optional.

[0051] The embodiment shown in FIG. 7 features two drive motors 70C coupled by means of a common drive shaft 72C for jointly rotating a pair of drive sheaves associated with counterweight assembly 450, and two drive motors 70R coupled by means of a common drive shaft 72R for jointly rotating a pair of drive sheaves associated with the rod string. This alternative drive motor arrangement could of course be used with other pumping unit embodiments.

[0052] It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the scope and teaching of the present teachings, including modifications which may use equivalent structures or materials hereafter conceived or developed. It is to be especially understood that the scope of the claims appended hereto should not be limited by any particular embodiments described and illustrated herein, but should be given the broadest interpretation consistent with the description as a whole. It is also to be understood that the substitution of a variant of a claimed element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure.

[0053] In this patent document, any form of the word “comprise” is intended to be understood in its non-limiting sense to mean that any item following such word is included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one such element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements in question, but may also extend to indirect interaction between the elements such as through secondary or intermediary structure. Relational terms such as “parallel”, “perpendicular”, and “concentric” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially parallel”) unless the context clearly requires otherwise. Wherever used in this document, the terms “typical” and “typically” are to be interpreted in the sense of representative of common usage or practice, and are not to be interpreted as implying essentiality or invariability.