CA3062084C

CA3062084C - Pump jack assembly

Info

Publication number: CA3062084C
Application number: CA3062084A
Authority: CA
Inventors: Gordon Abram; Tyler Haarstad; Everett Haarstad
Original assignee: Abram Gordon; Haarstad Everett; Variable Speed Hydraulics Inc
Current assignee: Variable Speed Hydraulics Inc
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2022-07-12
Anticipated expiration: 2039-11-20
Also published as: CA3062084A1

Abstract

ABSTRACT A pump jack assembly provides hydraulic operation of a pump jack by using a hydraulic motor that is driven by a hydraulic pump. The hydraulic motor is operatively connected to a crank arm to rotatingly drive the crank arm, which then drives a horse head of the pump jack through a walking beam. The hydraulic motor and hydraulic pump are connected in a closed- loop hydraulic system, rather than an open-loop hydraulic system. The hydraulic pump is operatively connected to a prime mover, which operates to drive the hydraulic pump. The hydraulic pump may include an internal hydraulic brake. The hydraulic pump may include an internal flow control valve. CA 3062084 2019-11-20

Description

PUMP JACK ASSEMBLY
FIELD OF THE INVENTION
[0001] The present disclosure relates to pump jack assemblies.
BACKGROUND OF THE INVENTION

[0002] Pump jacks are used to pump oil and fluids out of wells across the world. Pump jacks are powered by electric or fuel-powered engines connected to a transmission using belts or sheaves. The transmission turns a crank that rocks a horsehead back and forth.
The rocking horsehead reciprocates a polished rod connected by sucker rods to a downhole pump. Oil is returned up the well tubing and gas returns through the annulus between the tubing and casing. Vertical stroke pumping systems like the RotaflexTM system have been developed as a replacement for pump jacks.
SUMMARY OF THE INVENTION

[0003] The disclosure that follows describes a pump jack assembly having an improved hydraulic power system for a driving a pump jack.

[0004] Objects of the present disclosure is to provide a pump jack assembly with an improved hydraulic power system that has less moving parts, less hydraulic oil, fewer hydraulic hose connections, is more efficient, and is a closed loop hydraulic system as compared to an open loop hydraulic system.

[0005] In general, in one aspect, a pump jack assembly is provided. The pump jack assembly includes a walking beam pivotally mounted to a frame, a horsehead attached to a first end Date Recue/Date Received 2021-07-22 of the walking beam, a lever arm attached to a second end of the walking beam, and a crank arm operatively attached to the lever arm, the crank arm having one or more counter-weights, wherein rotation of the crank arm causes the walking beam to pivot and rock the horse head. A hydraulic motor is operatively connected to the crank arm to rotating drive the crank arm. A hydraulic pump is operatively connected to the hydraulic motor to drive the hydraulic motor by a fluid supply line and a fluid return line. A prime mover is operatively connected to the hydraulic pump to drive the hydraulic pump. And the hydraulic pump having an internal hydraulic brake that operates to restrict a flow of hydraulic fluid through the hydraulic pump to prevent the hydraulic motor from speeding up between an upstroke and a down stroke of the crank arm.

[0006] Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings.
The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

[0007] As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such Date Recue/Date Received 2021-07-22 equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

[0008] For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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:

[0010] Figure 1 illustrates side schematic view of a pump jack assembly; and

[0011] Figure 2 illustrates a top, partial view of a connection between a hydraulic motor and crank arm of the pump jack assembly.

Date Recue/Date Received 2021-07-22 DETAILED DESCRIPTION OF THE INVENTION

[0012] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

[0013] A pump jack (also called a nodding donkey, pumping unit, horsehead pump, rocking horse, beam pump, dinosaur, sucker rod pump, grasshopper pump, thirsty bird, or jack pump) is the overground drive for a reciprocating piston pump in an oil well.
Pump jacks are used to mechanically lift liquid out of the well when there is not enough bottom hole pressure for the liquid to flow all the way to the surface. Pump jacks are commonly used for onshore wells producing little oil.

[0014] Depending on the size of the pump, a pump jack generally produces five to forty litres of liquid at each stroke. Often this is an emulsion of crude oil and water. Pump size is also determined by the depth and weight of the oil to remove, with deeper extraction requiring more power to move the increased weight of the discharge column (discharge head).

[0015] A pump jack converts the rotary mechanism of a motor to a vertical reciprocating motion to drive the pump shaft and is exhibited in the characteristic nodding motion.
The engineering term for such a mechanism is a walking beam.

[0016] Modern pump jacks are powered by a prime mover, which is an electric motor or internal combustion engine. Common off-grid pump jack engines run on casing gas produced from the well, but pump jacks have been run on many types of fuel, such as propane and Date Recue/Date Received 2021-07-22 diesel fuel. In harsh climates such motors and engines may be housed in a shack for protection from the elements.

[0017] The prime mover of the pump jack runs a set of pulleys or belts on sheaves to the transmission, which drives a pair of cranks, generally with counterweights on them to assist the motor in lifting the heavy string of rods. The cranks raise and lower one end of an I-beam which is free to move on an A-frame. Positioned on the other end of the beam is a curved metal box called a horse head or donkey head, so named due to its appearance. A cable made of steel or fiberglass, called a bridle, connects the horse head to the polished rod, which is a piston that passes through the stuffing box.

[0018] The polished rod has a close fit to the stuffing box, permitting the rod to move in and out of the tubing without permitting fluid escape. The tubing is a pipe that runs to the bottom of the well through which the liquid is produced. The bridle follows the curve of the horse head as the head lowers and raises to create a nearly vertical stroke.
The polished rod is connected to a long string of rods called sucker rods, which run through the tubing to the down-hole pump, usually positioned near the bottom of the well.

[0019] At the bottom of the tubing is a down-hole pump. This pump usually has two check valves: a stationary valve at bottom called the standing valve, and a valve on the piston connected to the bottom of the sucker rods that travels up and down as the rods reciprocate, known as the traveling valve. Reservoir fluid enters from the formation into Date Recue/Date Received 2021-07-22 the bottom of the borehole through perforations that have been made through the casing and cement.

[0020] When the rods at the pump end are traveling up, the traveling valve is closed and the standing valve is open (due to the drop in pressure in the pump barrel).
Consequently, the pump barrel fills with the fluid from the formation as the traveling piston lifts the previous contents of the barrel upwards. When the rods begin pushing down, the traveling valve opens and the standing valve closes (due to an increase in pressure in the pump barrel). The traveling valve drops through the fluid in the barrel (which had been sucked in during the upstroke). The piston then reaches the end of its stroke and begins its path upwards again, repeating the process.

[0021] Referring to FIGS. 1 and 2, a pump jack assembly 10 is illustrated, having a horsehead 12, a polished rod 14, and a hydraulic motor 16. Horsehead 12 is mounted to rock back and forth on a frame such as an A-frame 18. Horsehead 12 may be connected to frame 18 through a walking beam 20. Polished rod 14 is connected to horsehead 12 and may be inserted through a stuffing box (not shown) into a well 22. Rod 14 may connect to horsehead 12 through a carrier bar (not shown) and cables (not shown).

[0022] Hydraulic motor 16 is connected to rock the horsehead 12. In the example shown, hydraulic motor 16 connects to crank arm 24, having one or more counterweights 26, through a belt and sheave assembly having a drive pulley 28, a driven pulley 30, and a belt 32 connected therebetween. The hydraulic motor 16 is connected to the drive pulley 28 by a conventional jackshaft 34 that is supported for rotating by bearings 36. While not Date Recue/Date Received 2021-07-22 shown, a transmission may be connected between the hydraulic motor 16 and the drive pulley 28 or a transmission may be connected between the driven pulley and the crank arm 24. The crank arm 24 may connect to beam 20 through one or more lever arms 38.

[0023] Thus, hydraulic motor 16 is connected to transmit rotational energy to crank arm 24, which converts such energy into reciprocal motion of horsehead 12, thus reciprocating rod 14 in and out of the well 22.

[0024] Hydraulic motor 16 may form part of a hydraulic power system 40. System 40 may include a hydraulic pump 42 and fluid supply and return lines 44 and 46, respectively, between the hydraulic pump and hydraulic motor 16 in a closed-loop hydraulic connection. Pump 40 may be driven by a motor 48, which may be a diesel, natural gas, or electrical motor. In the example shown motor 48 is powered by gas takeoff from well 22 through gas line 50. The motor 48 may be connected to the hydraulic pump 42 through a transmission 52.

[0025] As further depicted, a hydraulic oil reservoir 54 may be connected to the hydraulic pump 42 to supply hydraulic oil to the hydraulic pump. Additionally, an oil cooler or radiator 56 may be connected to the hydraulic oil reservoir 54 and the hydraulic pump 42 and operate to cool hydraulic oil circulating from the hydraulic pump to the hydraulic oil reservoir. An oil filter 58 may be connected between the radiator 56 and the reservoir 54.
Further, a crankcase vent line 60 may be connected between the hydraulic motor 16 and the hydraulic pump 42.

Date Recue/Date Received 2021-07-22

[0026] In certain embodiments, the hydraulic pump 42 may include an internal hydraulic brake 62 that is operable to restrict flow speed of fluid returning from motor 16 to the pump. In a conventional pump jack assembly that contains a non-hydraulic motor, rotational speed of crank arm 24 speeds up as counterweights 26 being a downstroke from the position shown and slows down as counterweights 30 begin an upstroke. Such imbalanced rotation wears down the belt and sheave system over time. However, in assembly brake 62 restricts or eliminates motor 16 from speeding up or slowing down as a result of crank 24 action, thus serving to correct and restrict rotational imbalances caused by counterweights 26. Smoother operation results. The brake may be adjustable, for example depending on the balance of the weights 26 compared to the rod weight.

[0027] In certain embodiments, the hydraulic pump 42 may include an internal flow control valve 64 to provide variable speed drive. Flow control valve 64 may be used to speed up or slow down pump jack speed on demand, for example by adjusting the set point. Thus, pump jack speed can be sped up or slowed down in seconds, permitting the pump speed to be tailored to match the rate at which the well 22 is producing. By contrast, speed changes in a belt and sheave system may require manually changing the size of the sheaves. One of ordinary skill in the art can select a suitably powered a hydraulic pump 42 to operate the hydraulic motor 16 to meet production demands. This hydraulic pump may include an internal hydraulic brake and/or a flow control valve. An example of a hydraulic pump may be a 90 Series hydrostatic pump made by Sauer.

[0028] Pump jack assembly 10 may be mounted at least partially on a pump jack 66 as shown. In a conventional pump jack system, pad 66 mounts the prime mover or motor (not shown).

Date Recue/Date Received 2021-07-22 In assembly 10, pad 66 may mount all, some, or none of the components of hydraulic system 40, thus providing flexibility in the location of components. In some cases, the components of system 40 may be provided on a separate skid or trailer (not shown).

[0029] In some cases, a conventional pump jack assembly may be retrofitted with hydraulic motor 16 to produce assembly 10. For example, an existing non hydraulic pump jack motor may be replaced by hydraulic motor 16.

[0030] While the invention has been particularly shown and described with respect to the illustrated embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

Date Recue/Date Received 2021-07-22

Claims

What is claimed is:

1. A pump jack assembly comprising:
a walking beam pivotally mounted to a frame;
a horsehead attached to a first end of said walking beam;
a lever arm attached to a second end of said walking beam;
a crank arm operatively attached to said lever arm, said crank arm having one or more counter-weights, wherein rotation of said crank arm causes said walking beam to pivot and rock said horse head;
a hydraulic motor operatively connected to said crank arm to rotating drive said crank arm;
a hydraulic pump operatively connected to said hydraulic motor in a form of a closed-loop hydraulic system to drive said hydraulic motor by a fluid supply line and a fluid return line;
a prime mover operatively connected to said hydraulic pump to drive said hydraulic pump; and said hydraulic pump having an internal hydraulic brake that operates to restrict a flow of hydraulic fluid through said hydraulic pump to prevent said hydraulic motor from speeding up between an upstroke and a down stroke of said crank arm.

2. The pump jack assembly of claim 1, wherein said hydraulic pump further includes an internal flow control valve that has an adjustable setpoint that controls a rotational speed of said hydraulic motor without changing a rotational speed of said prime mover.

3. The pump jack assembly of claim 1, further comprising a belt and sheave assembly operatively connecting said hydraulic motor and said crank arm.

4. The pump jack assembly of claim 3, further comprising a jack shaft operatively connecting said hydraulic motor to a drive pulley of said belt and sheave assembly.

5. The pump jack assembly of claim 1, wherein said prime mover is a combustion engine.

6. A pump jack assembly comprising:
a walking beam pivotally mounted to a frame;
a horsehead attached to a first end of said walking beam;
a lever arm attached to a second end of said walking beam;
a crank arm operatively attached to said lever arm, said crank arm having one or more counter-weights, wherein rotation of said crank arm causes said walking beam to pivot and rock said horse head;
a hydraulic motor operatively connected to said crank arm to rotating drive said crank arm;
a hydraulic pump operatively connected to said hydraulic motor in a form of a closed-loop hydraulic system to drive said hydraulic motor by a fluid supply line and a fluid return line;
a prime mover operatively connected to said hydraulic pump to drive said hydraulic pump;

said hydraulic pump having an internal hydraulic brake that operates to restrict a flow of hydraulic fluid through said hydraulic pump to prevent said hydraulic motor from speeding up between an upstroke and a down stroke of said crank arm;
wherein said hydraulic pump further includes an internal flow control valve that has an adjustable setpoint that controls a rotational speed of said hydraulic motor without changing a rotational speed of said prime mover; and a belt and sheave assembly operatively connecting said hydraulic motor and said crank arm.