Mobilized Tail Bearing Pumpjack

Abstract

A pumpjack includes a walking beam pivotally connected to a vertical support for oscillation in a generally vertical plane about a first axis. A first end of the walking beam is connected to a sucker rod string. A carriage is movably mounted to the walking beam to move back-and-forth along a length of a tail end of the walking beam. A pitman arm has a first end pivotally connected to the carriage for rotation about a second axis and a second end pivotally connected to a crank arm. A counterweight is mounted to the crank arm and a hydraulic ram is connected to the carriage to move the carriage back-and-forth along the walking beam and establish reciprocation of the sucker rod string.

Claims

1. A pumpjack for lifting fluid in a well bore, the pump comprising: a walking beam pivotally connected to a vertical support for oscillation in a generally vertical plane about a first axis, a first end of said walking beam connected to a sucker rod string; a carriage movably mounted on a bottom of said walking beam for movement back-and-forth below the walking beam along a length of a tail end of said walking beam; a pitman arm having a first end pivotally connected to a bottom of said carriage for rotation about a second axis and a second end pivotally connected to a crank arm; a counterweight mounted to the crank arm; and a hydraulic ram connected to said carriage beneath the walking beam for moving said carriage back-and-forth along said walking beam and establish reciprocation of the sucker rod string.

2. The pumpjack of claim 1, wherein said first and said second axis is disposed vertically below said walking beam.

3. The pumpjack of claim 3, wherein said first and said second axis are disposed along a common centerline that extends between said first axis and said second axis.

4. The pumpjack of claim 1, wherein said carriage is movable equal distances on opposite sides of a crank arm centerline that extends substantially vertical from a pivot connection between the crank arm and a second vertical support.

5. The pumpjack of claim 1, further comprising: one or more carriage stops mounted to said walking beam.

6. The pumpjack of claim 1, further comprising: a programmable logic controller, a hydraulic arm position sensor operatively connected to said hydraulic ram to determine the position of an extensible shaft of said hydraulic ram and output a hydraulic ram position signal that is indicative of the determined position of the extensible shaft; a beam position sensor operatively connected to said walking beam to determine the position of said walking beam and output a beam position signal that is indicative of the determined position of said walking beam; a load sensing spool valve operatively connected to said hydraulic ram to determine a load on said hydraulic ram and output a load signal that is indicative of the determined load on said hydraulic ram, said load sensing spool valve hydraulically connected to said hydraulic ram; a valve actuator operatively connected to said load sensing spool valve; said PLC electrically connected to said hydraulic arm position sensor to receive said hydraulic ram position signal, electrically connected to said beam position sensor to receive said beam position signal, electrically connected to said load sensing spool valve to receive said load signal; and said PLC programmed to operate said valve actuator based on said hydraulic ram position signal, said beam position signal, and said load signal to cause said hydraulic ram to move said carriage back-and-forth along said walking beam.

7. The pumpjack of claim 6, wherein said PLC is programmed to perform a maintenance shut down operation.

8. The pumpjack of claim 6, wherein said PLC is programmed to perform a travel to park position operation.

9. The pumpjack of claim 6, wherein said PLC is programmed to perform a balance operation.

10. The pumpjack of claim 6, wherein said PLC is programmed to perform a check for fluid level operation.

11. The pumpjack of claim 6, wherein said PLC is programmed to perform a swab well operation.

12. The pumpjack of claim 6, wherein said PLC is programmed to perform a produce well at maximum production rate operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following drawings illustrate by way of example and are included to provide further understanding of the invention for the purpose of illustrative discussion of the embodiments of the invention. No attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Identical reference numerals do not necessarily indicate an identical structure. Rather, the same reference numeral may be used to indicate a similar feature of a feature with similar functionality. In the drawings:

[0025] FIG. 1 is a diagrammatic illustration of the difference between arc of the beam and arc the bridle of a pumpjack, illustrating areas of inherent imbalance;

[0026] FIG. 2 is a diagrammatic view of a pumpjack constructed in accordance with the principals of an embodiment of the present invention;

[0027] FIG. 3 is a diagrammatic end view of a carriage and walking beam of the pumpjack illustrated in FIG. 2;

[0028] FIG. 4 is an enlarged, diagrammatic partial side view of the carriage and walking beam illustrated in FIG. 3;

[0029] FIG. 5 is an enlarged, diagrammatic partial side view of the walking beam and a saddle bearing spacer of the pumpjack illustrated in FIG. 2;

[0030] FIG. 6 is a block diagram of an exemplary control system of the pumpjack illustrated in FIG. 2; and

[0031] FIG. 7 is a diagram illustrating power regeneration (conservation) operation of a pumpjack in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring to FIGS. 2 through 5, there is representatively illustrated a pumpjack 10 that is constructed in accordance with the principals of an embodiment of the present invention. The pumpjack 10 includes a walking beam 12 that is pivotally connected to a vertical support 14 by a saddle bearing 16 so that the walking beam is able to oscillate in a generally vertical plane about the saddle bearing's rotation axis, similar to a conventional pumpjack. A horse head 18 is connected to front end 20 of the walking beam 12. And the horse head 18 is connected to a sucker-rod string 22 in a conventional manner by a bridle 24.

[0033] A carriage 26 is movably mounted to the tail end 28 of the walking beam 12 to move back-and-forth along a length of tail end 28. A tail bearing 30 is mounted to a lower end of the carriage 26 is pivotally connects an end of a pitman arm 32 to the carriage to rotate about the tail bearing's rotational axis. The opposite end of the pitman arm 32 is pivotally connected to a crank arm 34 and the crank arm is rotatably connected at one end to a vertical support 36. A counterweight 38 is attached to the opposite end of the crank arm 34.

[0034] A hydraulic ram 40 is mounted, for example, to the walking beam 12 and includes an extensible shaft 42 that is connected to the carriage 26.

[0035] As discussed further below, the hydraulic ram 40 operates to move the carriage 26 back-and-forth along the walking beam 12 by extending and retracting the extensible shaft 42. In an embodiment, the carriage 26 is movable equal distances on opposite sides of a centerline 44 that extends substantially vertically from the pivot or bearing connecting the crank arm 34 and vertical support 36. Further, the rotational axis of the tail bearing 30 and the saddle bearing 16 are disposed on a common centerline 46 that extends between the two bearings. In an embodiment, the tail bearing 30 and the saddle bearing 16 are positioned a same distance from the bottom of the walking beam 12. These arrangements, as will become apparent, permit certain operation of the hydraulic pump 10.

[0036] In the illustrated embodiment, the hydraulic ram 40 is mounted to a saddle spacer 56 that is disposed between the saddle bearing 16 and the walking beam 12. Saddle spacer 56 is sized so as to align centerline 46 generally horizontal along the bottom of the walking beam 12. And at initial setup, the walking beam 12 is balanced with the carriage 26 positioned so that the tail bearing 30 is located on the centerline 44 of the crank arm 34.

[0037] Alternatively, the hydraulic ram 40 could be replaced by an electrically power operator to move the saddle bearing along the walking beam in the manner discussed above.

[0038] As best seen in FIGS. 3 and 4, and in an embodiment, the walking beam 12 is an I-beam and the carriage 26 is movably mounted to the bottom flange of the I-beam by a system of rollers. Particularly, the carriage 26 includes two pairs of running wheels 48 and 50, one pair disposed along each side of the carriage and in rolling contact with a top surface of the bottom flange of the walking beam. Additionally, carriage 26 includes two pairs of up-stop wheels 52 and 54, one pair disposed along each side of the carriage and in rolling contact with a bottom surface of the bottom flange of the walking beam 12. The running wheels 48 and 50 bear the weight of the carriage 26 on the walking beam 12 and the up-stop wheels 52 and 54 prevent the carriage from coming up off the walking beam.

[0039] Further illustrated in FIG. 3, carriage limit stops 56 (only one is illustrated, the other is positioned on the opposite side) are mounted to the walking beam 12 to limit the carriage's forward travel along the walking beam. In an aspect, each limit stop 56 is wedge shaped and taper from narrow to wide in a direction from the tail toward the front of the walking beam and has a positive stop at the wide end. In an over travel condition, the limit stops 56 wedge between the up-stop wheels 52 and 54 and the walking beam 12 to prevent forward movement of the carriage.

[0040] Also illustrated in FIG. 4 is a carriage lock 58 that includes a structure 60 mounted to the walking beam 12, a corresponding structure 62 mounted to the carriage 12, and a pin or bolt 64 that can be inserted through apertures in structures 60 and 62 so as to lock the position of the carriage along the walking beam.

[0041] Referring to FIG. 6, there is diagrammatically illustrated an exemplary control system 66 for operating the hydraulic pumpjack 10. Control system 66 included a programmable logic controller (PLC) 68, a hydraulic ram position sensor 70, a beam position sensor 72, a load sensing proportional valve 74, and a valve actuator 76. The hydraulic ram position sensor 70 is operatively connected to the hydraulic ram 40 and outputs a signal that is indicative of the position of the ram's extensible shaft 42. The beam position sensor 72 is operatively connected to the walking beam 12 and outputs a signal that is indicative of the position of the walking beam. The load sensing proportional valve 74 operates to determine the load on the hydraulic ram and output a signal that is indicative of this sense load. The load sensing proportional valve 74 is also hydraulically connected to the hydraulic ram 40 and is operated by valve actuator 76 to control the hydraulic ram.

[0042] The PLC 68 is electrically connected to the hydraulic ram position sensor 70, the beam position sensor 72, the load sensing proportional valve 74, and the valve actuator 76. The PLC operates the valve actuator 76 as a function of the signals received by the hydraulic ram position sensor 70, the beam position sensor 72, and the load sensing proportional valve 74 to move the carriage 26 back-and-forth along the walking beam to drive the pump and reciprocate the sucker rod string.

[0043] Generally, reciprocation of the sucker rod string is accomplished using gravity by alternating the balance of the walking beam 12 between a tail heavy condition and a head heavy condition by moving the carriage 26 back-and-forth along the walking beam 12, which positions counterweight 38 to create either the tail heavy or head heavy condition.

[0044] With reference to FIG. 7, the pumpjack 10 is able to regenerate power throughout rotation of the counter weight crank arms, which is illustrated in four separate quadrants of rotation. Starting with quadrant one, the head is down and the pumpjack is head heavy. The carrier moves rearward causing the pumpjack to be tail heavy and to start lifting the head to horizontal (9:00 position). The bridle moves back to arc of head as the crank approaches horizontal (9:00 position), thereby making the pumpjack head light.

[0045] Continuing in quadrant two, the head is horizontal and weight on the bridle is following arc of the head, the head becomes lighter as the crank arms fall vertical (6:00 position). The carrier moves forward to shift from tail heavy to head heavy.

[0046] Continuing in quadrant three, the head is upward carrier moves forward to locate balance point (3:00 position) with the beam on the horizontal plane.

[0047] In quadrant four, the head falls below the horizontal, the bridle swings away from the beam, the head increasingly becomes heavy, and the crank arms accelerate (between 3:00 and 12:00 position). The carrier moves rearwardly to shift from head heavy to tail heavy.

[0048] Input energy required in quadrant three and one to move the carrier, crank arms accelerating in quadrant two. Inertia generated in quadrant two is conserved in quadrant three, so the more inertia gained in quadrant two (speed of rotation+unbalance), the deeper into quadrant three the crank arms will rotate. Therefore, less work is required in quadrant three to move the carrier to the balance point. Energy caused by unbalance in quadrant two is regenerated (conserved) into quadrant three. The same principal occurs between quadrants one and four. Further, inherent unbalance caused by the bridle arc is regenerated into input side of energy requirement.

[0049] The PLC 68 can be programmed to perform many different operations, several operations are discussed below.

[0050] 1. Maintenance Shut Down (ESD).

[0051] In this mode, the PLC 68 operates the hydraulic ram 40 to move the carriage 26 to the most rearward position, e.g., by fully extending the hydraulic ram so the pumpjack is maximum tail heavy and crank arm 34 is disposed at the 6 o'clock position. Indication is given to the operator to install carriage lockout pin and positive lock the crank arms. ESD the hydraulic supply. Await operator reset commands.

[0052] 2. Travel to Park Position.

[0053] In this mode, the PLC 68 operates the hydraulic ram 40 to move the carriage 26 forwardly along the walking beam toward the saddle bearing 16 until the crank arm 34 moves counter-clockwise to the 1 o'clock position. In this position, the walking beam 12 is head down and the pitman arm 32 is parallel to the crank arm 34. The pumpjack 10 is placed in this position when it shutdown to protect the sucker-rod string and polish rod inside the wellbore. Further, operation of the pumpjack 10 is most easily started from this position.

[0054] 3. Balance.

[0055] In this mode, and from the park position, the PLC 68 operates the hydraulic ram 40 to move the carriage 26 is rearward along the walking beam 12 until the crank arm 34 rotates in a clockwise direction and stabilize in the 3 o'clock position. (When the unit is first installed the physical weights are adjusted on the crank arms so that the full string weight and a full column of fluid with no fluid below the pump are balanced with the centerline of the tail bearing carrier on the centerline of the crankshaft).

[0056] 4. Check for Fluid Level.

[0057] In this mode, the PLC 68 operates to determine if the balance point determined in #3 above is forward of the crankshaft centerline it indicates that fluid has entered the wellbore in the annular space outside the production tubing. This will create buoyancy in the tubing string and make the pumpjack lighter at the head end. If no fluid is detected the pumpjack will shut down and go back to the park position #2 above.

[0058] 5. Swab Well.

[0059] In this mode, the PLC 68 is operates the hydraulic ram 40 to alternate moving the carriage 26 forward and rearward causing the pumpjack 10 to oscillate at a set speed. The pumpjack 10 can run in this configuration until the balance point has moved back to the centerline of the crankshaft (indicating a pumped off condition), at which time, the PLC will operating the park position mode. On a gas well that makes water, the jack can be instructed to swab by the external gas flow chart differential as well.

[0060] 6. Produce Well at Maximum Production Rate.

[0061] In this mode, the PLC 68 operates the hydraulic ram 40 to move the carriage 26 back-and-forth along the walking beam 12 to accelerate rotation of the walking beam until the sucker-rod string starts to float (hydraulic ram will see the floating if the rate begins to exceed buoyancy or friction factors present in the well). This is the maximum production rate possible with the least amount of energy expended. If the pumpjack 10 cannot attain this condition then the PLC instructions the operator to lengthen the stroke or in an extreme case require the well to be equipped with a bigger jack. This feature will allow the manufacture of the pumpjacks to reduce the number of jack sizes offered as the production rates attainable with any given stroke length can be optimized. The PLC is capable of learning to slow down pumping as the well approaches pumped off conditions and speed up to optimize production rates.

[0062] 7. Conduct Wellbore Diagnostics.

[0063] At all times during operation, the PLC 68 can detect wellbore conditions, pump efficiency, holes in production string, leaking travel balls, broken rods, tight packings, etc. by monitoring pressure balances across the hydraulic ram 40. The pumpjack 10, in essence, becomes its own dynamometer. The PLC 68 can easily be tied to SCADA control or even monitored with a mobile computing device.

[0064] A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. Preliminary Amendment