US3038310A - Combined oil tank and cylinder pedestal for hydraulic pumping unit - Google Patents

Description

June 12, 1962 G. H. WILLIAMS 3,038,310 COMBINED OIL TANK AND CYLINDER PEDESTAL FOR HYDRAULIC PUMPING UNIT Filed Feb. 25, 1960 2 Sheets-Sheet 1 1 a 76 a RESERVOIR 1 v.--

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J1me 1962 G. H. WILLIAMS 3,038,310

COMBINED OIL TANK AND CYLINDER PEDESTAL FOR HYDRAULIC PUMPING UNIT Filed Feb. 23, 1960 2 Sheets-Sheet 2 lA/viA/me 649w H. Mum/w:

United States 3,038,310 Patented June 12, 1962 3,038,319 COMBINED 01L TANK AND CYLINDER PEDES- TAL F012 HYDRAULIC PUMPING UNliT Glynn H. Williams, Huntington Park, Calif., assignor,

by mesne assignments, to Dynaquip, Long Beach, Calif.,

a corporation of Qalit'ornia Filed Feb. 2.3, 195i), Ser. No. 1,3i)2 5 Qlaims. (Cl. 6052) The present invention relates generally to fluid actuated pump control units, and it relates more particularly to an improved hydraulic pumping jack for use in conjunction with a reciprocating pump in an oil well for pumping oil from the well.

It is usual practice to use a reciprocating pump for the removal of oil from an oil Well. The reciprocating pump is positioned down in the production zone of the well, and it is controlled from the surface by means of a plurality of inter-connected rods which are usually referred to as sucker rods.

Reciprocal motion is imparted at the surface to the sucker rods so as to actuate the reciprocating pump down in the Well. The necessary reciprocal motion is supplied by a suitable power operated unit. The unit most commonly used in the past to provide the desired reciprocating motion to the string of sucker rods is an actuator commonly referred to as a walking beam actuator.

The walking beam actuator is subject to certain disadvantages, however, which have limited the constructional and working efliciency of this type of actuator. One disadvantage, for example, is that the walking beam actuator imposes excessive mechanical stresses on the sucker rod string. These mechanical stresses produce progressive fatigue of the metal forming the individual sucker rods and the couplings between the rods. This fatigue often results in fracture of the sucker rod string.

Because of the inherent disadvantages of the walking beam actuator, such as described above, actuators have been developed in the past which are capable of exerting reciprocating forces on the sucker rod string, and which do not have a tendency to produce excessively high mechanical stresses on the string. The latter type of actuator usually takes the form of a hydraulic pumping jack.

The hydraulic pumping jack provides smooth reciprocal operation for the sucker rod string in both directions of travel so that the mechanical stresses imposed on the string are materially reduced, as compared with the walking beam type of actuator. Also, a longer stroke may be achieved with the fluid actuated hydraulic pumping jack, as compared with the walking beam type, and other advantages may also be realized.

The present invention is concerned with the hydraulic type of pumping jack, and it is an object of the invention to provide a novel and improved construction for an actuator system of the hydraulic type in which an improved and eflicient circulation for the hydraulic fluid is provided, this being achieved without requirement for extraneous cooling or reservoir components.

Fluid actuated pumping jacks of the type presently under consideration usually include a power cylinder and an associated piston, the piston being slidable in the cylinder and being coupled to a polish rod which, in turn, is coupled to the sucker rod string. A valve controlled hydraulic system is used, in which a circulating pump cyclically introduces hydraulic fluid into the power cylinder to drive the piston upwardly in the cylinder, and in which the valve is controlled subsequently to release the piston so that it is moved downwardly by the weight of the sucker rod string to its lower position in the cylinder. This produces the desired reciprocal motion of the sucker rod string.

The power cylinder of the fluid actuated pumping jack referred to above is supported in an elevated position and its piston rod is coupled to the polish rod. The polish rod extends down into the well, and it is coupled to the sucker rod string, as mentioned above. The polish rod moves in packing glands at the top of the well, and these glands serve to remove most of the oil, water, dirt and sediment that tends to cling to the surface of the polish rod. However, a portion of these extraneous materials still cling to the polish rod, and this would have a harmful effect on the hydraulic system if they were allowed to enter the power cylinder, even in the smallest quantities. It is for that reason that the power cylinder must be held by suitable pedestals in an elevated position so that a length of piston rod may extend down from the power cylinder to be coupled to the polish rod, and so that no portion of the polish rod enters the power cylinder.

In most fluid actuated pumping jack installations, the rate of fall of the sucker rod string is controlled during the return stroke of the piston by releasing the hydraulic fluid in the cylinder under the control of the valve referred to above. The released fluid then flows through a metering orifice to reduce the rate of fall of the sucker rod string. This metering of the released fluid causes a material part of the energy of the falling sucker rod string to be transformed into heat in the hydraulic fluid, as the fluid resists the fall of the sucker rod string.

In order to provide cooling for the hydraulic fluid, and also to assure that an adequate supply of the fluid is supplied to the circulating pump of the hydraulic system, the prior art units usually incorporate some type of reservoir in the return path of the fluid. In addition, the more heavily loaded and faster operating assemblies of the prior art have required additional heat exchangers in series with the hydraulic conduit system to provide the required cooling of the hydraulic fluid.

The improved fluid actuated pumping jack of the present invention is constructed so that cooling of the hy draulic fluid is provided in conjunction with a fluid reservoir, and which cooling is in many cases adequate even for the fast operating and heavily loaded units.

In the embodiment of the invention to be described, for example, the power cylinder of a fluid actuated pumping jack is supported in an elevated position with respect to the top of the oil well with which the pumping jack is used. The elevated support of the power cylinder provides space for the usual connections and couplings to be made to the tubing, polish rod, and sucker rods which extend down into the well. The pumping jack of the embodiment of the invention to be described is supported in such an elevated position by one or more pedestals for the reasons described above. These pedestals, for example, may be cylindrical in shape, and they may each have a hollow interior. One feature of the assembly of the present invention is the provision of such pedestals, in which the hollow interiors are used to hold the amount of hydraulic fluid required by the system. These pedestals in the assembly of the present invention, therefore, in addition to performing a structural function of supporting the power cylinder in an elevated position, also serve as a fluid reservoir and provide radiation areas for the required cooling of the circulated hydraulic fluid.

The assembly of the invention described briefly above is advantageous in that the important requirements of providing a reservoir for the hydraulic fluid, and of providing a cooling means for the fluid, are met without the need for any separate extraneous components suitable for only one or the other of those purposes. Instead, these requirements are furnished by the structural pedestals themselves.

The combination of the invention is also advantageous in that the degree of cooling provided by the pedestal assembly is superior to the usual prior art arrangements which, in some instances, make use of a separate tank reservoir. The relatively long and narrow shape of the pedestal-reservoir assembly of the invention provides more radiating area per unit of volume than the usual short-length large-diameter type of prior art reservoir tank.

Moreover, the vertically disposed pedestal-reservoir assembly of the invention holds a major portion of the oil contained in the pedestals up from the ground and 1n the normal circulating air stream. This further enhances the cooling efiects realized in the assembly of the invention. More rapid cooling is also realized by the vertically disposed pedestal-reservoir assembly of the invention, as compared with the usual horizontal tank type, because the area of the pedestal-reservoir assembly actually exposed to the hot vertical rays of the sun is reduced to a minimum, and because more eflicient thermal circulation of the fluid is provided.

In addition to the features enumerated above, the use of the pedestal-reservoir assembly of the invention is advantageous because it serves to provide a relatively high pressure head for the hydraulic fluid at the intake of the circulating pump. This latter feature serves to increase the efficiency and effectiveness of the circulating pump.

It is, accordingly, an important object of the present invention to provide an improved and novel hydraulic pumping jack assembly which is eminently simple in its construction and in which adequate reservoir means for the circulating hydraulic fluid and adequate and improved cooling means for the fluid are provided under all operational speeds and loads of the assembly and without the need for additional components for these specific purposes.

In the drawings:

FIGURE 1 is a side elevational view of a fluid actuated pumping jack which may be used to control a reciprocating pump in an oil Welland which is constructed to incorporate the concepts of the present invention, this view illustrating a power cylinder supported in a vertical elevated position by a pair of pedestals, and a valved hydraulic system for controlling the operation of a piston in the power cylinder;

FIGURE 2 is a fragmentary elevational view of the system of FIGURE 1 on an enlarged scale, the latter view being partly in section to reveal the internal operating components of the power cylinder and to show a reverse valve in a first operating position and coupled to the cylinder; and

FIGURE 3 is a sectional view of the valve of FIGURE 2, but illustrating the reverse valve in a second operating position.

The fluid actuated pumping jack illustrated in FIGURE 1 includes a power cylinder which is supported in a vertical position by a pair of pedestal members 12 and 14. These pedestal members, as will be described in more detail in conjunction with FIGURE 2, are cylindrically shaped and each defines a chamber which is used as a reservoir and cooling chamber for the fluid circulating in the system.

The power cylinder 10 is mounted on an upper support member 16 which, in turn, is supported by, and structurally interconnects the upper ends of the pedestals 12 and 14. The assembly also includes a lower support member 18 which is afiixed to the bottom ends of the pedestals 12 and 14. The lower support member 18 is mounted on the upper end of a well casing 20 which extends down into the well receiving a polish rod and sucker rod string of conventional design.

The assembly of FIGURE 1 includes a circulating pump 22 which has an outlet fluid-coupled to a reverse valve 25 by means of a conduit 24.

The reverse valve 25, as will be described in more detail in FIGURE 2, causes the hydraulic fluid from the pump 22 to be introduced to the power cylinder 10 to move a piston upwardly in the cylinder when the valve is in a first operating position. When the valve is in its second operating position, the return hydraulic fluid is passed into and through the interiors of the pedestals 12 and 14, and the return fluid emerges from the lower end of the pedestal 14 through a conduit 26. The conduit 26 is coupled to a filter 28 which may be of usual construction, and the filter is coupled to the intake of the pump 22 through a conduit 30.

A valve 32 may be mounted in the conduit 26. For cleaning purposes, the valve 32 is closed and the casing of the filter 28 is opened slightly. The circulating pump 22 is operated for a brief interval so as to draw the residual hydraulic fluid out of the filter 28. The cartridge of the filter may their be removed for cleaning or replace ment purposes.

As shown in FIGURE 2, the illustrated fluid actuated pumping jack includes the vertically extending cylinder 10 which is mounted at its lower end on a base member 34 which incorporates a stufling box 36. The base member 34 is mounted on the lower support member 16 referred to above.

The top of the cylinder '10 is closed by a cap 38. A piston 46) is slidably disposed within the cylinder 10 for vertical reciprocal movement with respect to the cylinder. The piston 40 is rigidly secured by a clamp 42 to a piston rod 44, which extends down the longitudinal axis of the cylinder 10 and through the stufiing box 36. The piston rod 44 is coupled at 45 to the polish rod referred to above, and the polish rod, as mentioned, is coupled to the sucker rod string down in the well.

The circulating pump 22, which is driven by an electric motor 23, provides the pressurized hydraulic fluid for actuating the piston 40. The vertical reciprocating movement of the piston is controlled by the reverse valve mechanism 25.

The piston rod 44 extends through an upper packing gland 36a and through a lower packing gland 36b in the stuffing box 36. A chamber 36c is formed in the stuffing box 36 between the glands 36a and 36b. The gland 36b is relatively loose fitting on the rod 44 and, as will be described below in more detail, the chamber 360 is maintained at sub-atmospheric pressure to assure that any fluid leaking past the gland 36a and adhering to the rod 44 will be drawn into the chamber 36c. Various types of valves may be employed at 25 in the present system.

One such reverse valve mechanism is described, for example, in Patent No. 2,729,941 which issued January 10, 1956 to Howard E. Rose et al. and the present embodiment will be described as incorporating such a valve.

The valve mechanism includes a block having therein a vertically extending cylindrical chamber 52, and a horizontally extending cylindrical pilot valve chamber 54. A control valve element 56 is slidably disposed within the vertical chamber 52 for reciprocal movement and pilot valve element 58 is slidably disposed Within the horizontal chamber 54 for reciprocal movement in the latter chamber.

The control valve element 56 includes a head 60 at its lower end and a collar 62 formed at its upper end. The head 60 and the collar 62 are substantially equal in diameter. The control valve chamber 52 is fluid-coupled to the lower end of the cylinder 10 by a conduit 64. The chamber 52 is also fluid-coupled to the outlet of the circulating pump 22 by the conduit 24 referred to in conjunction with FIGURE 1 and also indirectly to the intake of the circulating pump 22 by a return circuit including a conduit 66 which extends into the interior of the pedestal 12.

As illustrated in FIGURE 2, the conduit 66 is coupled to the chamber in the pedestal 12 so that the return hydraulic fluid enters the interior of the pedestal 12 through the pipeline 66 and fills that pedestal and (as will be described the pedestal 14 to a desired operating fluid level. This level is normally above a lower limit established by a pressure valve 68. The pressure valve 68 senses the static pressure of the fluid in the pedestals 12 and 14 and shuts off the system if the level falls below the lower limit.

An air filter 72 is mounted on the top of the pedestal 14 and provides an air path from the interior of the pedestal. Lower and upper conduits 70 and 76 intercouple the interiors of the pedestals 12 and 14 to equalize the fluid levels therein. The conduit 26 is coupled through the valve 32 to a point in the pedestal 14 near the bottom of that pedestal, as mentioned above. The small lower conduit 70 functions merely to equalize the fluid levels in the pedestals 12 and 14 when the system is drained.

Adverting to a description of the reverse valve, it will be seen that the control element 56 is continuously biased downwardly by a helical compression spring 80. This spring is positioned within a cavity 82 which is connected by a passageway 84 to the return conduit 66.

The left end of the pilot valve chamber 54 communicates with the lower end of the cylinder by a passageway 86 and .a connecting conduit 88. The passageway 86 is also coupled to the pipeline 64 by a vertical passageway 90. The passageway 90 is normally closed by an upwardly acting spring loaded pressure release valve 92.

The left hand portion of the pilot valve chamber 54 communicates with the lower end of the control valve chamber 52 by a passageway 94. Another passageway 96 connects the lower end of the control valve chamber 52 with the intermediate portion of the pilot valve chamber 54. A vertically extending passageway 98 connects the lower end of the control valve chamber 52 and the pilot valve chamber 54, joining the latter at a point spaced to the right in the drawings of the junction of the passageway 96 with that same chamber 54. The last mentioned chamber 54 is in constant communication with the return pipe line 66 over a limited region through another vertically extending passageway 99. Connection of the passageway 99 and the chamber 54 is at a location spaced slightly to the right in the drawings of the connection of passageway 98 and the chamber 54. The right end of the pilot valve chamber 54 is connected by a pipeline 100 to the interior of the power cylinder 10 at a point just above the lowest point normally reached by the top of the piston 40 during its downward stroke.

The pilot valve chamber 54 includes an enlarged portion 102 between the junction of passageway 99 and the right end of the chamber. This enlarged portion 102 is connected by a pipeline 104 with the interior of the cylinder 10 just below the highest point reached by the piston 40 during its working upward stroke.

The pilot valve element 58 includes a main land 106, a second land 108 formed at its right hand end, a collar 110 formed to the left of the second land 108, a stem 185 between the main land 106 and the collar 110, and annular grooves 186 and 188 formed in the stem 185. The latter grooves are adapted to receive a ball detent 190 which is constantly biased upwardly by a helical compression spring 192. This spring 192 is disposed within a pocket 194 formed in the control valve block 50.

During operation of the pumping jack the piston 40 reciprocating in the cylinder 10 acts not only as a primemover for the sucker rods but may be considered as a pump alternately increasing and decreasing the air pressure in the cylinder above the piston. This pumping action is employed to evacuate the chamber 360 in the packing box 36. This is accomplished by fluid connecting the upper interior of the cylinder 10 with the chamber 36c through conduits 196 and 196a, each having a check valve in it as indicated at 196b and 196d.

Thus on the down stroke of the piston 40, air and hydraulic fluid leakage is drawn out of the chamber 36c 6. and into the upper part of the cylinder 10. On the next up-stroke of the piston such hydraulic fluid plus any that leaks past the piston 40 is discharged through the conduit 196 and a branch conduit 1960 into the upper end of the pedestal 12.

The branch conduit 1960 discharges tangentially into the interior of the pedestal 12 so that the hydraulic fluid flows spirally down the interior surface thus to remove foam therefrom and enhance the cooling thereof.

The details of operation of the valve assembly 25 are described in the aforementioned'Patent No. 2,729,941. Suflice it to say for the present purposes, the pilot valve member 58 is shuttled back and forth in the horizontal chamber 54 thus effecting vertical reciprocation of the control valve element 56 to alternately admit and release power fluid under the piston 40.

The pilot valve member 58 is actuated as aforesaid by pressure alternately applied through conduits and 104 as the piston 40 passes the points at which said conduits connect to the cylinder 10.

The head 60 of the control valve element 56 is tapered so as to throttle the fluid discharged through the return conduit 66. The amount of throttling on the return fluid may be controlled by a threaded set screw 195. This action reduces the speed of the return stroke of the sucker rod string to a desired slow rate. However, the reduction in the speed of the return stroke of the sucker rod string by the throttling of hydraulic fluid creates heat in the return fluid.

The return hydraulic fluid passing through the conduit 66 as mentioned above, absorbs heat in its resistance of the downward movement of the piston 40 and the attached sucker rod string. The heated return fluid enters into the interior of the pedestal 1 2 and fills that pedestal and the pedestal 14. The hotter fluid in the interior of the pedestal 14 rises in the pedestal and circulates through the conduit 76 to the pedestal 12. The cooler fluid at the bottom of the interior of the pedestal 14 is drawn by the conduit 26 back to the intake of the circulating pump 22.

The disposition of the pedestals 12 and 14 in the return path of the hydraulic fluid forms a reservoir for the fluid to assure an adequate supply of fluid to the circulating pump 22 at all times. In addition, the pedestals 12 and 14 form an improved cooling means for the return hydraulic fluid.

Although the illustrated system has been described as incorporating a pair of pedestals 12 and 14, it is obvious that any desired number of pedestals may be used. Many constructional embodiments of the invention are presently in use which have three such pedestals fluid-connected to one another so that the return hydraulic fluid circulates up and down through successive pedestals before being returned to the circulating pump.

The high ratio between the length and diameter of the edestals provides a high radiating area per unit volume of the hydraulic fluid circulated through the pedestals. In addition, the vertical disposition of the pedestals causes any circulating air streams to have an optimum cooling effect on the fluid circulating through them.

Also, and as mentioned above, the disposition of the pedestals is such that they present a minimum area to the direct vertical rays from the sun. This latter feature is important in that the pedestals preserve their cooling capabilities even in sunlight.

Also mentioned, the circulating pump 22 may be positioned, as shown in FIGURE 1, to be below the bottom ends of the pedestals 12 and 14 so that a pressure head of fluid may be formed for the pump so as to increase its efliciency.

I claim:

1. In a fluid actuated control apparatus which includes a pump having an intake and an outlet and providing a source of pressurized hydraulic fluid, a vertically positioned power cylinder, and a piston slidably disposed in the cylinder for axial reciprocal movement with respect thereto; the combination of; first fluid conducting means including a valve and coupled to the cylinder and to the outlet of the pump for introducing the pressurized hydraulic fluid from the pump to the lower end of the cylinder in a first operating position of the valve so as to drive the piston upwardly in the cylinder and for conducting the return hydraulic fluid from the cylinder in a second operating position of the valve and upon the downward return of the piston in the cylinder, a plurality of upright hollow cylindrical-shaped pedestal members aflixed to the power cylinder for supporting the power cylinder in an elevated vertical position, each of the pedestal members having a length which is long with respect to the diameter thereof, second fluid conducting means coupled to the first fluid conducting means and to at least one of the pedestal members for introducing the return hydraulic fluid into the hollow interior of such pedestal members, third fluid conducting means coupled to the pedestal members for causing the return fluid to circulate through the pedestal members, and fourth fluid conducting means coupled to at least one of the pedestal members and to the intake of the pump for passing the return hydraulic fluid from the hollow interior of such pedestal member to the intake of the pump.

2. In a fluid actuated pumping jack for use at the surface of an oil well and for actuating a reciprocating pump positioned down in the well, and which pumping jack includes a circulating pump having an intake and an outlet and providing a source of pressurized hydraulic fluid, a vertically positioned power cylinder, a piston slidably disposed in the cylinder for reciprocal movement with respect thereto, and means including a string of sucker rods for coupling the piston to the reciprocating pump; the combination of: first pipeline means coupled to the power cylinder and to the outlet of the circulating pump, a valve interposed in the first pipeline means for causing pressurized hydraulic fluid from the circulating pump to be introduced to the lower end of the power cylinder in a first operating position of the valve so as to drive the piston upwardly in the cylinder and for causing the return hydraulic fluid to be conducted out of the cylinder in a second operating condition of the valve and upon the downward return of the piston in the cylinder, a plurality of upright hollow cylindrical-shaped pedestal members aflixed to the power cylinder for supporting the power cylinder in an elevated vertical position, each of the pedestal members having a length which is long with respect to the diameter thereof, second pipeline means coupled to the valve and to at least one of the pedestal members for introducing the return hydraulic fluid into the hollow interior of such pedestal member, third pipeline means coupled to the pedestal members for causing the return fluid to circulate through the pedestal members, and fourth pipeline means coupled to at least one of the pedestal members and to the intake of the circulating pump for passing the return hydraulic fluid from the hollow interior of such pedestal member to the intake of the circulating pump.

3. In a fluid actuated control apparatus which includes a pump having an intake and an outlet and providing a source of pressurized hydraulic fluid, a power cylinder, and a piston slidably disposed in the cylinder for axial reciprocal movement with respect thereto; a combination of: first fluid-conducting means including a valve and coupled to the cylinder and to the outlet of the pump for introducing pressurized hydraulic fluid from the pump to one end of the cylinder so as to drive the piston in one direction in the cylinder and for conducting return hydraulic fluid from the cylinder in a second operating position of the valve and upon return movement of the piston in an opposite direction in the cylinder, two upright hollow cylindrical-shaped pedestal members aflixed to the cylinder for supporting the cylinder in an elevated position, each of said pedestal members having a length which is long with respect to the diameter thereof, second fluid-conducting means coupled to the first fluidconducting means and to one of the pedestal members adjacent its lower end for introducing the return hydraulic fluid into the hollow interior thereof, third fluid-conducting means coupled to the pedestal members adjacent their upper ends for circulating fluid therebetween, and fourth fluid-conducting means coupled to the other of said pedestal members adjacent its lower end and to the intake of the pump for passing the return hydraulic fluid from the hollow interior of said other of said pedestal members to the intake of the pump.

4. The subject matter of claim 1 further characterized in that said second fluid conducting means is coupled to a given one of said pedestal members and said fourth fluid conducting means is coupled to another of said pedestal members.

5. The subject matter of claim 2 further characterized in that: said third pipeline means includes upper and lower conduits coupled to said pedestal members adjacent their upper and lower ends, respectively; said second pipeline means is coupled to a given one of said pedestal members intermediate the couplings of said upper and lower conduits; and said fourth pipeline means is coupled to another of saidpedestal members below the coupling of said lower conduit.

References Cited in the file of this patent UNITED STATES PATENTS 1,035,431 Ericson Aug. 13, 1912 1,815,399 Curnutt July 21, 1931 2,131,910 Vernon et al Oct. 4, 1938 2,136,986 Vernon et a1 Nov. 15, 1938 2,279,057 Reed Apr. 7, 1942 2,540,347 Pounds Feb. 6, 1951 2,581,430 Mork et al Jan. 8, 1952 2,729,941 Rose et a1. Jan. 10, 1956

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