US2325138A - Hydraulic pumping jack - Google Patents

Description

July 27, 1943.

s. c. KYLE ETAL. 2,325,138

HYDRAULIC PUMPING JACK Filed April 9, 1940 3 Sheets-Sheet 1 INVENTORS July 27, 1943'. s.. c.-KYL l-:ET Al.

HYDRAULIC PUMPING JACK l 3 Sheets-Sheet 2 Marga/7 WZ |NvENToR5 (/y -Filed April 9, 1940 JUE? 2?? 43- s. c. KYLE ET AL 2,325,138

HYDRAULIC PUMPING JACK Filed April 9, 1940 s sheets-sheet s "f1-"I" I E' 75 m@ g/g/ Wm WM AT RNEY Patented July 27, 1943 HYDRAULIC PUMPING JACK Samuel Clyde Kyle, San-Francisco, and Ira Morgan White, akland, Calf., assignors to The Pelton Water Wheel Company, San Francisco, Calif., a corporation of California Application April 9, 1940, Serial No. 328,686

1 Claim.

Our invention relates to means for transmitting power from the ground surface to a pump located a great distance below the surface of the ground or at a very substantial distance away from the motive force. A usual field of 1nstallation is in connection with the pumping of petroleum products, such as oil together with some gas, from relatively great depths.

'I'he patent, literature contains a number of disclosures of arrangementsincorporating positive displacement pumps located at the bottom or adjacent the bottom of oil wells and connected by a length, usually several thousand feet-for example, 5,000 to 12,000 feet, of pump rod, to a motor or engine adjacent the surface of the ground. One of the great problems 1nvolved in such an installation arises out of the elasticity of the relatively long pump rod, which is sufcient to render inexact, both in magnitude and in phase, the correspondence between the pump stroke at the bottom of the well and the engine stroke at the surface of the ground. It happens in practice that the reciprocatory pumping motion results in the transmission of wave vibration along the pump rod so that local stresses are not only very great but are sometimes in excess of the capacity of the material and pump rod breakage occurs. Such breakage not only results in a discontinuance of the pumping operation and some damage to the pump rod which mustV be replaced, but often results in very serious damage to the motive machinery which tends to disrupt itself when suddenly relieved of the pumping load.

It is therefore an object of our invention to provide an improved hydraulic pumping jack.

Another object of our invention is to provide a pumping jack which is protected against damage due to pump rod or other operating failure.

Another object of our invention is to provide a pumping jack in which the stresses in the pumping rods are maintained below maximum amounts.

A further object of our invention is to provide a pumping jack which is versatile in its capabilities so as to minimize installation difculties of a relatively standard unit under different environmental conditions.

An additional object of our invention is to provide a hydraulic pumping jack which is susceptible of precise adjustment, not only to accord with the original installation conditions but also to accommodate variations in such conditions from time to time.

The foregoing and other objects are attained in the embodiment of the invention illustrated in the drawings, in which- Fig. lis a schematic diagram of a hydraulic pumping jack in accordance with our invention;

Fig. 2a is a cross-section on a vertical transverse plane, of the actuating unit of our hydraulic jack, a portion of the balancing unit being shown, while Fig. 2b is a continuation of Fig. 2a, being a cross-section vertically on thestated transverse plane but showing the lower portion of the balancing mechanism and the connection of the pumping jack to the casing head; y

Fig. 3 is a plan of a base plate on which the electric motor and the main pump are mounted;

Fig. 4 is a side elevation of the structure shown in Fig. 3;

Fig. 5 is a cross-section, to an enlarged scale, the plane of which is shown by the .line 5-5 of Fig. 4;

Fig. 6 is a cross-section the plane of which is indicated by the line t--t of Fig. 5; and

Fig. 7 is a detail cross-section the plane of which is indicated by the line 1`i of Fig. 6.

In its preferred form, the hydraulic pumping jack of our invention includes an actuating structure adapted for installation at the head of a Well and for connection by a pump rod to a displacement pump adjacent the bottom of the well, the pump rod itself being connected to a balancing piston and to an actuating piston which are located respectively in a balancing cylinder and in an actuating cylinder, these being provided with hydraulic connections to a balancing tank and to a controlled supply and discharge of actuating fluid. For the controlv of the actuating fluid there is provided a hydraulically actuated valve responsive to the position of the actuating piston Within the actuating cylinder, in accordance with a predetermined but variable selection thereof, the valve also being regulable to aord various rates of acceleration and `deceleration of the actuating cylinder piston. In addition, there are Various means for checking or arresting the operati-on of the structure in the event of unusual conditions or breakage.

Although the hydraulic pumping jack of our invention is not so restricted, it is typically installed in connection with a subterranean oil well which is provided with an outer casing 6 extending from the surface of the ground to a point many feet therebelow, usually a point in the neighborhood of from flve to twelve thousand feet below the surface of the ground. Within and coaxial with the casing 8 there is an interior pipe 1 which houses a pump rod or polish rod 8 extending to the actuating element of the positive displacement pump (not shown) located adjacent the bottom of the well. The casing 6 is provided with a flange 9 having a terminus which receives a ring |2 on which a supporting collar I3, in threaded engagement with the interlor pipe 1, rests. 'I'he ring |2 is retained in place by an adapter section |4 clamped in position to the `terminus I I by fastening means I8. Extending from the chamber |6 defined by the tubes 6 and 1 and capped by the ring l2, is an outlet conduit |1 for conducting gas emanating from the well to any convenient place. Somewhat similarly, above the collar I2 and from a chamber I8 defined by such collar, the adapter |4 and a diaphragm I9 extending across and forming part of the-adapter, is a conduit 2| for conducting pumped `oil to any suitable location.

The adapter section |4 is continued in a skeleton manner above the diaphragm I9 to be open to the atmosphere. The diaphragm is pierced by the polish rod 8 which also pierces a base 22 incorporated in the adapter I4 and designed to receive a motor or driving structure. Leakage into the open adapter section is prevented by a lower packing 23 and an upper packing 24. The skeleton construction of the upper portion of the adapter facilitates access to the packings 23 and 24.

By this construction there is formed beneath the balancing piston 28 a balancing chamber, generally designated 32, communication with which is had by a conduit 33 of considerable diameter, which is joined to an adapter opening 34 integrally formed with the head 26. The conduit 33 is connected to a balancing tank 31, conveniently mounted upon a base plate 38, in turn mounted on a foundation 39, and comprising a generally closed metallic vessel having operating iiuid 4I in its lowermost portion and having in its upper portion a gas 42, such as ordinary air or an inert gas such as nitrogen which is capable of being repeatedly compressed and decompressed. In effect, the balancing tank 31 acts somewhat as a surge chamber for alternate flow from such tank into the balancing chamber 32 and from such balancing chamber 32 back to the balancing tank 31, the flow through the conduit 33 being generally unrestricted and having but slight frictional retardation. The amount of fluid 4| maintained in the balancing chamber and the pressure therein are preferably arranged so that a predetermined portion of the load upon the polish rod 8,l due to external factors, is substantially or entirely balanced. The amount of unbalance, if any, which is permitted to remain varies with diffrent installations and can be established at any desired value by appropriately regulating the characteristics of the balancing tank 31 with respect to the remaining parts of the structure.

At its upper end the balancing chamber shell 21 is fitted into an upper head 43 which is seeured with respect to the remaining part of the structure by through-bolts 44 paralleling the shell 21 and engaging the upper part of the adapter I4 to ailord a rigid assembly. The head 43 denes an enclosed chamber 46 encompassing a polish rod 41 which is,`to all intents and purposes. an extension or continuation of the polish rod 8. 'Ihe chamber 46 is terminated at its upper portion by a transverse diaphragm 48 -containing a packing 49 to preclude leakage. It is intended that normally the chamber 46 be subject to a pressure in the neighborhood of atmospheric, preferably below the actual pressure of the atmosphere and perhaps considerably below actual atmospheric pressure. This range of pressure in the neighborhood of atmospheric is referred to herein as substantially atmospheric. To prevent the accumulation of leakage oil in the chamber 46, it is provided at one side with a scavenge outlet 5| which is connected by a pipe 52 to the inlet 53 of a scavenge pump 54 which is of sufllcient capacity normally to maintain the desired pressure within the chamber 46. The pump 54 is of the positive displacement gear type and includes a drive shaft 56 which is coupled to any suitable source of power, such as an electric motor 51, mounted on the base plate 38, so that during the operation of the mechanism accumulated leakage oil within the chamber 46 is withdrawn through the pipe 52 and passes to the scavenge pump 54 from the outlet 58 of which it passes through a return pipe 59 to the balancing tank 31, joining the mass 4| of fluid therein.

The section 43 above the diaphragm 48 serves as the lower head for an actuating chamber 6I deilned not only by the head 48 but by a circularcylindrical shell 62 coaxial with the polish rod 41 and held in place with respect to such rod not only by the member 43 but by an upper head 63 positioned by through-bolts 64 engaging the member 43. Operating within the chamber 6I is an actuating piston 66 having rings 61 thereon to reduce leakage and suitably secured to the polish rod 41 for reciprocatory movement Within the cylindrical shell 62. Leakage past the piston 66 is removed from the chamber 68 above the piston 66 through a. leakage conduit 69 connecting with a pipe 1I leading into the chamber 46 from whence the leakage oil can flow through the pipe 52 as previously described. In addition to the leakage pipe connection 69, the head 63 is provided with a lifting boss 12 to assist in dismantling or moving the attached structure.

Since the piston 66 is designed to be lifted by iiuid pressure, and since its stroke is variable Without mechanical restraint thereupon except what is due to the weight of the load upon the polished rod 8, We provide means for precluding severe damage in the event the polish rod 8 should break and suddenly relieve the actuating piston 66 of its load. Under these conditions, the actuating piston 66 would ascend very rapidly within the cylinder 62 until such time as it uncovered, beyond its maximum normal stroke or above the end of such maximum normal stroke, a relatively large port 13 which is connected by a large duct 14 to the conduit 1| which itself has a considerable diameter. This conduit of large diameter communicates through a large opening with the chamber 46 from which there is but the small opening of the port 5| for scavenge purposes. Hence, when the load is suddenly relieved from the rod 8 and the piston 66 rises above the port 13, the pressure fluid beneath the piston, which is tending to press it upwardly, iiows out through the port 13 through the large pipe 1| and into the chamber 46 above the balancing piston 28. This piston is consequently subjected to the full pressure of the actuating fluid as the leakage port 6| is much too small to carry off more than a fraction of the entering fluid. Since the balancing piston 28 is somewhat larger in diameter than the actuating piston 66, as soon as the port 13 is uncovered and a transfer of fluid takes place, there is an immediate and very large arresting force exerted upon what remains of the polish rod 8, so that, instead of damage ensuing, the reciprocatory mechanism, after it passes its maximum normal stroke, is quickly arrested without damage.

In the event of sudden imposition of excess load in the opposite direction, for instance if the supply of actuating fluid to the chamber 6| should suddenly fail when the polish rod 8 is fully loaded, then the piston 66 descends rapidly to its normal lower stroke limit. Butshortly below this point the piston 28 enters the bore of the lower head section 26 the outlet 34 from which is spaced above the bottom thereof and communicates therewith through a decreasingly tapered channel 15. The piston 28 and the section 26 therefore act together as an arresting dashpot, precluding damage.

If desired, the lower end of the chamber 6| can also be constructed as is the lower end of the section 26, so that, by co-operating therewith, the piston 66 will augment the dashpot effect of the piston 28 in emergencies. v

The normal entrance of motive fluid to the actuating cylinder 6| is through a relatively large conduit 16 opening into the upper portion of the structure 43 and extending into communication with a valve casing 11, so that actuating fluid alternately flows in the conduit 16 in opposite directions to and from the valve casing to lift and lower the actuating piston 66 and its attached mechanisms. Conveniently, the valve casing 11 is disposed as a part of the housing 18 surrounding and supporting a main gear-pump 19 which is mounted on the base plate 38 and which includes the drive shaft 56, so that not only is the scavenge pump 54 driven by the electric motor 51 but likewise the main pump 19 is simultaneously driven thereby. The main pump 19 includes bearings 8| for the drive shaft 56 as well as bearings 82 within the casing 18 for a pump idler gear 83. The pump gears are disposed within an interior pump casing 84 and their direction of rotation is such that a port 86 in the interior casing 84 serves as a discharge port into a chamber 81 enclosed between the interior casing 84 and the exterior housing 18.

Within the valve casing 11, which is integral with the outer pump housing 18, there is disposed a sleeve 9| which has various ports therein for regulating flow to and from the pump. Thus, there is centrally disposed a low-pressure port 92 open to the pump inlet and, adjacent lthe ends of the sleeve, a pair of high- pressure ports 93 and 94 which latter communicate with the chamber 81. Also piercing the sleeve 9| is a port 96 forming the outlet of the pipe 16 which leads to the actuating chamber, as Well as a port 91 which is capable of establishing communication with the balancing tank V31 through a pipe 98 extending .from the port to a junction with the transfer pipe 33.

Adapted to operate within the sleeve 9| to govern the fluid flow between the various ports, there is provided a piston valve, generally designated IUI, which includes an axial stem |02, a

center `land |83, and end lands |04 and |86. When the piston valve |8| is inv one extreme position, as shown in Fig. 6 of the drawings, the pipe 98 is placed in communication with the low-pressure side 82 of the pump, while the conduit 16 is placed in communication with the high-pressure chamber 81 thereof. Thus, fluid is extracted fromthe balancingtank 31 by the pump and is forced into the actuating cylinder 62, thereby lifting the piston 66 therein and eiIectuating an oil pumping stroke. But, when the piston valve 'IGI is in its opposite extreme position, as shown in Fig. l of the drawings, then the conduit 16 is in communication with the low-pressure port 92, while the conduit 98 is placed in communication with the high-pressure chamber 81, and the pump is effective to withdraw uid from the chamber 6| and to transfer or discharge it into the balancing tank 31, thus permitting the piston 66 to lower by gravity but at the rate of withdrawal of the" actuating fluid by the pump 18. Thus, if the piston valve |8| ls made to reciprocate between its extreme positions, there will be a corresponding reciprocation of the pis'-v ton 66 and a resulting pumping action.

The maximum downward acceleration is normally limited bythe liquidwithdrawing or evacuating capacity of the main pump 19 acting through the pipe 16, and the maximum upward acceleration may be similarly limited or may be established by a by-pass valve |81 set to allow flow through a pipe |88 from the pipe 16 directly to the conduit 98 leading to the tankv 42 whenever the pressure within the pipe 16 is twice the pressure within the tank 42, for example.

We preferably provide means for controlling the piston valve |0| in accordance with several factors, some at least of which are adjustable or variable. For example, under variable conditions at one installation, or even under varying conditions in different installations, itis desirable to vary the length of stroke ofthe piston 66. This is for several reasons, one of which is that different stroke pumping units may be disposed at the bottom of the well to which the operatingl structure is to be connected, and another of which is the amount of'stretch or yield of the long pumping rod. That is, under some conditions, a required stroke of eight feet in a pump at the bottom of the well, because of the elongation of the rod, requires a considerably greater stroke of the actuating unit. Furthermore, conditions of pumping change; for example, the relative proportion of gas and oilln the pumped uid, which render a variation in stroke desirable. While a normal stroke is in the neighborhood of approximately ten feet, and any fraction of that or a similar quantity can be utilized, we have illustrated herein an arrangement in which five various strokes are possible in accordance with the operators selection. We therefore provide means which are responsive to a selected position of the piston 66 within the cylinder 82, for affecting the piston valve |0| to end the upstroke of the piston 66.

At appropriately spaced intervals along the walls' of the cylinder 62, we provide a plurality of conduits ||2 and the like, all of which preferably extend to a ported casing ||3 wherein a selector H6 is disposed. The selector is always connected by a duct ||6 to the'piston valve |0I, albeit sometimes indirectly, so that by appropriately positioning the selector I4 the device can be made responsive to any selectedposition of the p iston 66. That is, when the piston Il in rising uncovers the selected one of` the conduits III, ||2 and the like, the pressure iluid within the cylinder 62 then flows through the connected one of the conduits I I I, II2 and the like and, through the selector II4, into the conduit IIB.

Usually it is not necessary to have any stroke variation at the bottom portion of the piston travel, and but a single control point is necessary there. At the same time, if desired, the plurality of portsutilized at the upper end of the cylinder and their selector valve can be substantially duplicated at the lower end. As illustrated, however, there isa single lower control port |I8 which is uncovered when the piston approaches the lower portion of its stroke, so as to subject such port to substantially atmospheric pressure. When the piston is above such port it is subjected to the same pressure that existswithin the line 16, for example, which is considerably above atmospheric. In order that the higher pressure will not be eiective upon thev control instrumentality as the piston in rising uncovers the port I I8, but will be eiective only as the piston in rising uncovers the selected one of the ports II I or |I2, we provide a pipe |I9 connecting the port III with the pipe I6 but interpose a check valve |2| in the pipe |I9 which is closed Iby higher pressure in the chamber 6|, and also interpose a check valve |22 in the pipe II6 between the selector valve ||4 and the junction of the pipe I I9, which check valve is closed by higher pressure on the side ofthe pipe II9. Thus, whether or not the high pressure in the pipe I I6 drops to its lower value depends upon the uncovering of the port II8 by the descending piston 66 adjacent the lower part of the stroke, while the increase of pressure within the pipe IIB from the lower value to the higher value depends only upon the uncovering of the selected one of the ports ||I and ||2 by the ascending piston 66 adjacent the upper portion of the stroke.

In accordance with our invention, we do not actuate the piston valve directly but utilize a pilot valve or servo mechanism for this purpose in order to increase the sensitivity of response of the mechanism. For that reason the pipe IIS is connected to a chamber |23A formed in a pilot valve body |24 secured to one end of the housing 11. Within the chamber |231 is a diierential piston plunger |26 which has a relatively large piston head 21 operating within the chamber |23 and subject to the pressure variations in the line ||6. Acting upon the opposite side of the piston head |21 is pressure fluid within a chamber |28 which is in communication through a duct |29 with the high-pressure chamber 81 of the main pump. But the entire face of the piston |21 is not effective within the chamber |28 since there merges therewith a smaller piston |3I operating within a cylinder |32 of reduced diameter, which cylinder is then enlarged for communication through a. pipe |33 with the inlet 53 of the scavenge pump 54. Leading from the cylinder |32 through a port |4| is a. duct |42 the pressure in which is utilized to control the ypiston valve I8 I To determine the particular pressure from time to time existing within the duct |42 in co-operation with the piston I3I, there is a piston head |43 on the stem of the plunger |26 of substantially the same diameter as the head I3I. The relationship of the piston heads |3| and 43 is such that in one extreme position thereof the high-pressure conduit |29 communicates through the cylinder |32 with the pipe |42 and consequently subjects the pipe |42 to the relatively high pressure of the discharge of the main pump; whereas in the other extreme position of the piston heads I3I and |48 the pipe |42 is in communication through the cylinder |32 with the pipe |33 extending to the scavenge pump 54, thus subjecting the pipe |42 to a relatively low pressure.

The action of the diierential piston plunger |28 in occupying either of its extreme positions is subject to the pressure existing within the duct II6. For example, when the duct I|6 is substantially at atmospheric pressure, then the much higher pressure from the pump 81 through the pipe |28 is eiective to displace the head |21 within the chamber |23 toward the left in Fig. 1 and to permit immediate communication between the duct |29 and the pipe |42. When, however, the pressure in the pipe I I6 is increased due to uncovering of the selected one of the ducts III, |I2 and the like by the ascending piston 66, then such superior pressure is effective upon the entire face of the head |21 to displace the differential piston valve toward the right, as seen in Fig. 1, within the chamber |23, not only to cut off communication between the pipes |29 and |42 by the action of the piston head |3I but also to uncover direct communication between the pipe |42 and the pipe |33 by displacement of the piston head I 43, so that the pressure within the pipe |42 is immediately varied from its maximum value to its minimum value. When the pressure inthe pipel I6 drops, the reverse action of the plunger |24 occurs and the pressure in the pipe |42 is immediately increased to the higher value. The extreme pressure variation in the pipe |42, which occurs almost instantly despite the relatively gradual uncovering of the ducts I I and ||2 or II8, is effective to produce acorresponding operation of the main piston valve IIJI, although, in the event a slower operation of the main valve is indicated-which it usually is to afford a smooth reversal of stroke, we provide in the duct |42 a regulable needle valve |46 for governing the rate of flow therethrough to the conjoined portion of the pipe |42.

The regulated flow into and from the pipe |42 is utilized differentially to actuate the piston valve IUI. The valve at this end operates within the sleeve 9| to dene a chamber |48 in communication with the duct |42 so that the entire cross-sectional area of the valve piston is subjected to the pressure transmitted by the pipe |42 to the chamber |48. Extreme movement of the valve IIlI toward one end of the chamber |48 is regulated by an adjustable set-screw |49 enclosed in a cap I5| to preclude external leakage.

At its opposite end, the valve I IlI is likewise limited in stroke by a similar adjustable setscrew |52 which is enclosed in a leakage-preventing cap |53 and which is effective against a reduced stem |54. This stem is part of the valve I 0| and is slidable within a chamber |56 always in communication with the high-pressure charnber 81 of the main pump through a conduit |51. A chamber |58, intervening between thev differentia1 area of the land IilG and the body |59 within which the stem |54 operates, is connected to the scavenge pump 54 by a pipe |6| extending from the chamber |58 to a junction with the pipe 52.

When the relatively high pressure from the main pump is solely e'ective within the chamber |56 upon the stem |54, the valve IOI is translated to an extreme position against the stopscrew |49, and this is the case when the pressure within the pipe |42 is relatively low, which occurs just after the rising piston 66 has uncovered one of the ports1 such as ||2, for example. This is the condition illustrated in Fig. 1, in which the valve IUI places the actuating cylinder 62 in communication with the low-pressure side of the main pump so as to return the piston. But, although the high pressure continues to act within the chamber |56 against the stem |54 during most of the descent of the piston 66, when the piston` 66 approaches the lower end of its stroke and uncovers the port ||8 to the atmospheric pressure existing above the piston 66, then the pressure within the chamber |23 drops, and the pilot valve |26 is translated so as to connect the high-pressure pipe |29 through the pipe |42 to the chamber |48, thus subjecting the relatively large end of the piston valve to high pressure. This `pressure is substantially the same as that in the chamber |56, but since the area of the end of the piston |0| is considerably greater than the effective area of the stem |54, the valve |0| is translated into a position connecting the pipe 'I6 with the high-pressure chamber 8l of the main pump. Consequently, again there is exerted an upward pressure on the piston 66 to begin a new stroke in an upward direction.

ySince the rate of translation of the main valve from one extreme position to the other is dependent upon the rate at which fluid can ow into and out of the chamber |48 through the pipe |42, and since this rate of oW isunder the control of the needle valve L46, the rate of reversal of the piston 66 'at the top and at the bottom of its stroke can be set at any desired value, thereby precluding the occurrence of excessive stresses in the polished rod 8. None of the various valves is balanced in any intermediate position but all are positively impelled from one extreme position to the other so that they cannot stick or balance in any intermediate location to stall operation. Thus, the ordinary operation of the structure is very smooth and exactly as adjusted and regulated, although the y length of the stroke can readily be altered by changing the selector valve position. Yet if an accident should occur and the polish rod 8 should break, the structure is automatically arrested at the upper extremity of the stroke by virtue of by-passing of the actuating fluid to form an ar` resting cushion; or, if there should be a sudden actuating fluid failure, the construction of the lower part of the actuating cylinder is such as to arrest the piston if it should move accidentally in that direction beyond its maximum stroke.

We claim:

A hydraulic pumping jack comprising a polish rod, a balancing cylinder of predetermined diameter coaxial therewith, a balancing piston in said balancing cylinder and fast on said rod to provide a balancing chamber below said piston and retarding chamber above said piston, an actuating cylinder of smaller diameter coaxial with said rod, an actuating piston in said actuating cylinder to provide an actuating chamber below said actuating piston and another chamber above said actuating piston, means for supplying working uid under pressure to said actuating chamber and means for supplying fluid under a lower pressure to said balancing charnber, means including a restricted conduit for withdrawing fluid from said retarding chamber, a conduit having a diameter relatively large with respectto said first-mentioned conduit and connecting said retarding chamber and said other chamber and means for connecting said working chamber with said retarding chamber and said other chamber upon an upward stroke of said actuating piston above the normal maxinium stroke thereof, said restricted conduit constituting the sole outlet for fluid from said retarding chamber and said other chamber during said upward stroke above said normal maximum stroke.

SAMUEL CLYDE KYLE. IRA MORGAN WHITE.

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