US2259019A - Apparatus for pumping oil wells - Google Patents

Description

0t.14,1941. R. H. CA R ETAL 2,259,019

' APPARA'I FJS FOR PUMPING OIL WELLS Filed June 7, 1959 A Sheets-Sheet l 6740 LBS. DEAD LOAD cormzc'ren T0 BEAM HANGER I225 L88. ZERO LOAD l9l00 LBS. WITH POLISHED ROD DIRECT 8 aw y Oct. 14, 1941. R. H. CARR ETAL APPARATUS FOR PUMPING OIL WELLS Filed June '7, 1939 4 Sheets-Sheet 2 car U-Q 0 H. rm 1 M m 4 mz 0 3 1 n E 82 1 wmmw 1 wmrM E L'H w no 4 (U v2 1 fl 1 4 W m 9 4 0 v 0 Z 1 m w 9 J a 3 a Z 2 4 9V .3 (Jhiu Z 00 M 1 F 2 R. H. CARR ETAL 9 APPARATUS'FOR PUMPING OIL WELLS Oct. 14, 1941.

Filed Julie 7, 1939 4 Sheets-Sheet 3 L1H... mmmwmfi nm wmma fimMwl 0 fi w 2 2 4 Patented Oct. 14, 1941 APPARATUS FOR PUD/[PING OIL WELLS Richard H. Carr, Chicago, 111., and Kenneth A. Covell and Charles F. Terrell, 'Jr., Tulsa, Okla., assignors, by mesne assignments, to Sullivan Machinery Company, a corporation bf Massachusetts Application June 7, 1939, Serial No. 277,844 8 Claims. (01. 255-16) Our invention relates to pumpingapparatus, and more particularly to apparatus for pumping oil wells by means of the raising and lowering of sucker rods connecting a pump in the well to an actuating device, particularly one of the beam type, upon the surface. From another aspect, our invention relates more generally to devices for minimizing'stresses between a source of reciprocating motion and devices reciprocated thereby.

For the pumping of oil wells of considerable. depth beam well pumping is by far the most common method used. This method is, as has long been recognized, subject to serious difiiculties, however, as rod breakage is very common and the resultant pulling and replacement expense may be serious. Peak loads imposed upon the rods with this type of pumping device are high. The stress range is comparatively great. The power consumption is also more than would be requisite to do the useful work accomplished. And the relative positiveness, so to speak, of the whole system contributes seriously to the reduction in sucker rod life.

It is an object of our invention to provide an improved pumping system. It is another object of our invention to provide an improved pumpactuating apparatus. It is a further object of our invention to provide an improved device for reducing sucker rod peak loads and stress ranges in beam type pumping systems. It is a still further object of our invention to provide an improved arrangement for minimizing stresses between a source of reciprocating motion and the device reciprocated. Other objects and advantages of our invention will hereinafter more fully appear. v

In the accompanying drawings, in which for purposes of illustration an illustrative embodiment and several modifications of our invention have been shown- Fig. l is an elevational view, in somewhat diagrammatic form, of a pumping system in which the preferred embodiment of the invention is incorporated.

Fig. 2 is an enlarged vertical sectional view, on the planeof the line 2--2 of Fig. 1, through the shock-reducing cyl-inderand piston mechanism of the preferred embodiment.

Fig. 4 is an enlarged vertical section on a plane corresponding to the plane of Fig. 2, showing a modifiedform of shock-absorber cylinder and piston mechanism.

Fig. 5 is a view similar to Fig. 4, showing the parts of the device of that figure in difierent relative positions.

Fig. 6 is an enlarged vertical section on a plane corresponding to the plane of Fig. 2, showing a further modified form of shock-absorber cylinder and piston mechanism.

.Fig. 7 is a view similar to Fig. 6, showing parts of the device of Fig. 6 in different relative positions;

Fig. 8 is a diagram showing superimposed'on each other dynagraph cards with and without theuse of an embodiment of our invention.

In the accompanying drawings, referring first to Figs. 1, 2, 3 and 8, it will be noted that the 'polished rod l arranged atthe top of the sucker of reducing peak loads and rod stresses; and this mechanism I0 is connected through a suitable clamp mechanism I l to the polished rod line I.

Referring now more particularly to Figs. 2 and 3, it will be noted that the apparatus l0 comprises a cylinder l2 having a top head l3 and a bottom head l4, the heads and cylinder being held in assembled relation by any suitable means,

such as the tie bolts or rods [5 Within the bore.

' the clamp mechanism II with the polished rod Fig. 3 is a 'view similar to Fig. 2 but showing the parts in different relative positionsa Fig. 3 is a detail sectional view showing a: modification of the structure shown in Figs. 2 and 3.

I, while ears I9 carrying a pin 20 serve to provide a pivotal connection between the beam hanger 8 and the apparatus Ill. The lower head I4 is provided with a suitable gland 22 and packing 23 to preclude leakage of pressure downwardly along the piston rod l8 from the space below the piston H. The upper end of the cylinder bore [6 is provided with a port 24 continuously connecting the interior of the cylinder with the atmosphere .except when the piston ll in certain upper positions thereof closes the port 24. The port 24 is arranged a suitable distance below the upper end to each other of the head l3 and piston ill will be suitably cushioned. The port 26 permits breath ing of the cylinder on relative separation between the piston I l and the top cylinder head it as soon as the port 26 is uncovered.

Means'is provided for maintaining a compare.- 1

tivelyi'ligh pressure beneath the piston at all times during normal pumping, but one (a pressure) which will not fluctuate very substantially upon relative movement of the piston il and the cylinder l2 varying the distance between the pls= ton ll and the lower cylinder head M. To this end there is provided a lateral opening 271 spaced a suficient distance above the bottom of the cylinder to provide a cushion should the air pressure that normally keeps the piston H and the lower cylinder head it apart suddenly he vented. The opening 2? is connected by a suitable ilexible conduit 28 of large flow area, with an appropriate source of pressure, later to be described but which may be notedin passing to be of such large volume that relative movements between the cylinder 62 and piston ll will not cause material fluctuations in pressure.

In view of the maintenance of a comparatively high pressure below the piston H and a pressure above the piston, when thepiston ll? is remote from the head it, substantially equal to atmospheric pressure, it is evident that there may be some leakage past the packing rings 29, but such leakage will immediately be vented through the port to.

To supply pressure to the opening 21 any suitable means may be employed. And we herein disclose as illustrative of. any suitable initial source of high gaseous pressure a, compressor 85 driven by any suitable means, herein diagrammatically represented by the belt 36 This compressor is of the comparatively high pressure type and capable of pumping to a pressure of 250 pounds or more, and may desirably be multi-stage in construction. Its discharge line 31 is provided with a relief valve 38 and is connected through piping 39 with a tank 40, which may be termed, for convenience, an unloader tank. The tank 40 is connected by a. line M to a pilot valve 42 controlling any suitable type of unloading geans (not shown in detail) for the compressor of the beam 5.

vIf desired, an auxiliary control of the pressure supply system may be provided, as at 41, utilizing a pressure switch of any suitable conventional type receiving air pressure ifrom apoint beyond the pressure reducing valve 43 and controlling a circuit to an electric driving motor for the belt 36, and starting 'said motor whenever the pressure in the line 44 falls below a desired minimum value and stopping 71111011 an increase to a desired maximum value; It will be evident that thenature of the controls and even of the lib type of pressure source may be widely varied within the scope of our invention.

It is important, in order that the stresses imposed on the suclrer rod line shall not be great, that while the apparatus it must provide for the transmission of a sucker rod raising force adequate to raise the rods under all circumstances, yet there should bee. yielding within the device ill which will preclude the transmission of excessive pressures to the sucker rod line. It is therefore important that relative separation of the piston ll and the upper cylinder head It shall not be attended by the building up of a high pressure through the compression of the fluid below the piston; and for this reason the receiver '66 is made of very substantial volume and will have its conduit 28, through which it is connected to the cylinder M, of substantial flow area, so that upward movement of the cylinder it at a faster rate than the upward movement of'the piston ll shall not be able to cause the building up of a substantially higher pressure than prevails during down strokes beneath the piston ll. It will be understood that by the proper predeterminatlon of the pressure within the beam receiver (i6 and the effective cross sectional area of the piston Ill, the device it may be caused to be certain to possess the capacity to raise the full load of the sucker rods and the oil without the necessity of the piston resting on the lower head it; while by approprlamly proportioning the pipe 28 and the receiver ($6 the avoidance of excess stresses may be realized.

It will be evident that under the action of gravity the piston il, unless prevented, might, with the apparatus shut down and the air pressure reduced through leakage or otherwise, assume a position resting upon the bottom cylinder head It. If the pressure in the receiver tank 36 be built up a sufficient time before the apparatus is put in operation, leakage downward past the rings 29 would ultimately produce a pressure below the piston sugficient to uncover the port 21; and thereupon the piston would promptly move to approximately the position shown in Fig. 3. If it is not desired to depend upon leakage past the rings,- other expedients might be resorted to,

'21 would be covered, or to permit very quickly a temporary initial delivery of fluid to the bottom of the cylinder bore it. As one mode or assuring the presence of pressure beneath the piston ll there might be mentioned the employment of a rod clamp such as is shown at 34 in Fig. 1. This rod clamp could be applied temporarily or permanently, as desired, to the polished rod at a position thereon in which it would prevent downward movement of the piston ll relative to the cylinder I2, below a. position in which in the lowermost position of the lifting end of the beam the cylinder I! will not have its pressure supply opening 21 at least partially below the lower edge or the piston. 01 course as soon as adequate pressure is built up beneath the piston there will be no further movement or the piston downward again, so long as the system operates normally, for enough to permit engagement oi the rod clamp 34 with the stalling box or any special abutment that may be provided for engagement thereby, to

limit the downward movement of the polished rod and the-parts connected thereto. As may be more clearly apparent following a discussion, which will shortly be presented, or the mode of operation or this device, when the cylinder I 2 is pumping.

just attaining its lowest position the piston I'I will ordinarily be in its highest position in the cylinder .I2, and thus there will be no tendency for the rod clamp ever to contact the stuffing box or other abutment means therefor during normal In Fig. 3 there is shown a bypass 49 opening through the lower head I4 and having a manually operable stop valve 50 between its ends for conducting at will fluid from the conduit 28 directly to the bottom of the cylinder bore l6. If it is not desired to use a rod clamp or to rely on leakage past the rings 29, this arrangement shown in Fig. 3 will permit, by the opening of the valve 50, the delivery of high pressure fluid substantially instantly beneath the bottom of the piston l1, and the raising of the latter above the port 21; and as soon as the piston has been raised above the port 21 the manually operable valve 50 can be immediately closed and the presence of a cushion at the bottom of the cylinder assured.

If it be assumed that in Fig. l the beam is stationary and that air has been delivered in some The mode of operation of the structure so fardescribed will be self-evident. At the beginning of each full upward movement of the right-hand end of the beam 'S'the piston II will be adjacent the top of the cylinder l2. By the time the beam has assumed a horizontal position the piston I! will have lagged behind the cylinder a substantial amount. By the time, however, when the righthand beam end reaches its uppermost position, the piston I! will again be adjacent the top of the cylinder. On the down stroke of the right-hand end of the beam the piston I! will of course remain adjacent the top of the cylinder l2, as the pressure below the piston will be more than ade-' quate to support the weight of the rods on the down stroke. l

Now, the mode. of operation of the whole system may be briefly described. Before starting up the beam, the compressor 35 will be operated to build up the pressure in thesystem to the requiredyalue, and through the excess of pressure beneath the piston the latter will be raised to approximately the position shown in Fig. 3. The beam may then be placed in normal operation, and from then on the pressure is automatically maintained by the compressor control system. With a suitable pressure in the system the piston I! will remain adjacent the top of the cylinder I 2 the clearance tank, the volume of the latter, and,

the magnitude of the well load.

Because of the selected ratio to the sucker rod line load of the product of the pressure below the piston and the area of the piston, when the linev tension tends to increase, the pressure under the piston will be ineffective to sustain the load, and the cylinder moves upwardly relative to the piston until the point in the stroke of the beam is' crease is passed. In this manner, peak loads which are encountered. in conventionah beam pumping are avoided. The pistonwill be adjacent the top of the cylinder at the beginning and at the end of each up stroke, but will be at some lower position during the range of high peak loads occurring in the middleof the'up stroke. 0n the down stroke the piston will of course remain adjacent the top of the cylinder, as the pressure carried will overcome the weight of the rods on the down stroke.

From the foregoing description, it will be evident -that we have provided an apparatus which will greatly reduce the rod loads and which will, further, substantially reducethe stress range in the rods. There will also be a reduction in the power required to operate the pumping system.

Before describing the other modifications of the invention which are herein disclosed for purdynagraph cards superimposed upon each other,

. one reproduced in heavy line and one in lighter line, the card in light lin showing the results obtained witha solid connection betweenthe beam line and the polished rod, and the one in heavier line corresponding to the card obtained with the use of our present invention. It should be pointed out that the latter card was not made with a device corresponding exactly in all details to the illustrative embodiment which has been hereinabovedescribed, and the lighter card was also not made with a'beam type pumping apparatus corresponding precisely in dimension to the one shown. However, these cards ll Serve to depict fairly the comparative results of the use of our invention, and the actual structure used in the production of the heavy-lined card embodied in our invention.

' 36.3, in the particular test made, to 29.6.

It will be observed that by somewhat increas-.

ing the pressure below the piston I'I. a reduced relative motion between the piston and cylinder is obtainable, but that this results in a higher rod load. In general it has been observed that the more the pressure is lowered,-within limits, v

below the piston l1, and the greater the relative piston motion, the lower the maximum polished rod load, the greater the load reduction, the lower the rod stress in pounds per square inch, and the lower the stress range. At any given installation the pressure utilized will be determined to provide the best results for the particular conditions encountered.

Referring now to the embodiment of the inventionshown in Figs. 4 and 5, it will be observed that there is a general correspondence b tween the structure of these figures and that of Figs. 2 and 3 and corresponding parts have been given like numbers. There is a cylinder l2 having an upper head l3 and alower head M, and suitable holding means l5 holding the heads and cylinder in assembled relation. The piston l1, which is reached where the tendency of line tension to 111-.75 reclprocably arranged within the bore l6 of the cylinder I2, differs somewhat in proportion and in construction from the piston I1. It will be observed that herein the piston I1 is shown somewhat longer than the piston I1 and is surrounded between its ends by an annular groove 5I connected to atmosphere by a radial passage 52 and a passage 53 extending longitudinally through the piston rod I8, and having a vent port 54 opening to atmosphere through the wall of the piston rod at a point which is never covered by the gland 22 associated with the lower head I4. A lateral port 21 and a breather port 56 open through the walls of the cylinder at points spaced, respectively, from its lower and upper ends. The breather port 55 is arranged in such relation to the upper head I3 of the cylinder I2 that in the uppermost position of the piston H the annular groove 5I never attains to communication with the port 56; and the groove 5I never attains communication, in the lowermost position of the piston I1, with the port 21. The port 56 is not at all times in free communication with the atmosphere, but instead is provided with a check valve device 51 having a swinging valve element 58 therein. The valve 58 is of the inwardly opening type. It will be evident that if the valve 58 were to become closed and the pres sure above the piston I1 were to build up through leakage past the rings 29 upon the piston, there would, in the absence of the annular groove 5| and the venting means provided therefor, build up in time such a pressureabove the piston-as to preclude the intended mode of operation of the there will be, during a portion of the upward travel of the cylinder, a movement of the latter upwardly relative to the piston and the taking in of a small quantity of air, ordinarily, through the check valve device 51 into the space above the piston. As the upward movement of the device. However, any leakage of fluid upwardly I from the comparatively high pressure space below the piston I1 past the rings 29 is prevented from tending to equalize the pressure above and below the piston, since as soon as the fluid passing upwardly between the piston and cylinder walls attains to the groove 5|, it is immediately vented through thepassages 52 and 53 and the port 54.

The mode of operation of this device can be readily understood, for it will be appreciated that the port 21 is connected by a suitable connection 28 with a receiver tank corresponding to the tank 46 of Fig. 1.

The disposition of the port 56 at a definite distance below the upper head I3 of the cylinder makes certain the existence of a definite cushioning action under all circumstances, as there is relative approach between the head l3 and the piston I1; and even were the valve mechanism 51 not to function as intended, there would be a positive entrapment of air during atileast the last portion of the relative upward movement of the piston within the cylinder. The valve 51, as has been noted, is of a type adapted to let in air to, but to hinder escape of air from, the upper end of the cylinder; Obviously, on relative separation of the head I3 and the piston I1, when the pressure within the space above the piston becomes materially less than atmospheric, the valve mechanism 51 will permit air to enter the upper end of the cylinder; and the pressure at the upper end of the cylindenwfll not exceed the value which will be attained by the compression of the air that will enter the upper end of the cylinder when the piston I1 is at its maximum distance from the head I3. I

It will be understood now that upon the attainment of air at the pressure within the tank 46 cylinder slows down, as the right end of the beam approaches its uppermost position, the piston will overtake, so to speak, the cylinder and there will be a somewhat greater cushioning than in the form of the invention first described, due to the presence of the check valve device 51. With this exception-and it will be understood that any change in proportions which may be occasioned by this difference in cushioning action will be duly made-the general mode of operation of the structure of Figs. 4 and5 will be the same as that with the structure of Figs'." 2 and 3. It is therefore believed unnecessary to describe in further detail the specific operation of this embodiment of the invention.

In Figs. 6 and 7 still another embodiment of certain aspects of the invention is shown. In this embodiment parts corresponding generally to parts in Figs. 2 and 3 and/or Figs. 4 and 5 are indicated by reference characters which are double primed, and corresponding parts are indicated by like reference characters. The essential difference, aside from a somewhat shortening of the piston I1" from what is shown in Figs. 4'and 5 (this shortening being made possible by reason a nections 21 are replaced by a passage 60 opening directly through the bottom of. the cylinders lower head I4, and the connection 28 enters the head of the cylinder and communicates with the port instead of being connected to the side of the cylinder proper.

A detailed description of the mode of operation of this species of the invention is not necessary, because afull understanding will be had by simply noting the fact that there is'no dashpot type cushioning with this embodiment of the inven- ;tion possible at the lower end of the cylinder,

because this elimination of the side connection with the tank 46 and the substitution of the bottom passage 60 do not permit the complete pressure below the piston I1, are necessary.

beneath the piston I1, the latter will be moved upward to approximatelythe position shown in Fig. 5. Then during the lifting stroke of the beam, with resultant raising of the cylinder I2,

From the foregoing description of the various embodiments of our invention from its structural aspects, it will be apparent that we have provided simple and highly practical devices for the purposes set forth, some possessing certain advantages and others others; that these devices reduce the peak polished rod loads; that they reduce polished rod horsepower; reduce stress range: and do not result in any loss of stroke,

based on experience to date, that rod partings may be reduced by ninety percent, and the ex;

departing from its spirit or the scope of theappended claims. What we claim as new and desire to secure by Letters Patent is:

1. In an apparatus of the nature described. a cylinder, a piston therein, a connection with a substantial volume of gaseous fluid underpressure exceeding atmospheric opening through the side of the cylinder at a point spaced from one end of the latter, and a lateral opening communicating with atmosphere for the influx and discharge of fluid spaced from the other end of the cylinder a distance less than the length of said piston.

2. In an apparatus of the nature described, a cylinder, a piston therein, a connection with a substantial volume of gaseous fluidunder pressure exceeding atmospheric opening through the side of the cylinder at a point spaced from the 4 bottom of the latter less than the length of the piston, and a lateral opening communicating with atmosphere for the influx and discharge of fluid spaced from the top of the cylinder less than the length of said piston.

3. In an apparatus of the class described, a cylinder having a piston movable therein and dividing the interior of said cylinder into spaces that change in volume on relative movement between the cylinder and piston, said cylinder and pansible chamber having a communication with said. confined volume of fluid subject to interruption of flow from the former to the latter automatically in the event of diminution of said chamber size below a predetermined minimum.

5. In an apparatus of the character described, the combination with a member to be reciprocated and a'walking beam for reciprocating said member, of apneumatic shock absorber pivotally suspended from the operating end of said beam and operatively connected to said member to be reciprocated-and comprising a fluid cylinder containing a reciprocable piston and means for controlling thepressure of the fluid in the ends of the cylinder at the opposite sides of said piston, said pressure-controlling means including a source of high pressure fluid communicating with the cylinder at the lower'side of said piston, and

means including passage means 'having check valve means associated therewith for controlling the supply of fluid at atmospheric pressure to the space within the'cylinder at the upper side of said piston, the points-of communication of said high pressure fluid source and said passage means with said cylinder being spaced from the ends of said cylinder to provide cushioning spaces for said piston.

6. In an apparatus of the character described,

a cylinder, a piston therein, a connection with a v Q substantial volume or fluidcon'tinuous'lyunder pressure exceeding atmospheric and. openingthrough the side of the cylinder at apoint spaced from the bottom of the latter less than'the length of the piston, valve controlled passage means for placing said pressure volume in communication with the bottom of said cylinder, and an opening communicating with atmosphere forthe influx and discharge of fluid to the top of said cylinder.

piston having provision for the connection of one of them to a sucker rod line and of the other of them to a walking beam, means for subjecting the space within said cylinder which diminishes in volume during raising of the sucker rod, to a pressure, and means for precluding leakage of said pressure past the piston to the opposite side of the latter, including a peripheral groovein the piston and means for venting said groove to the exterior of said cylinder.

4. In combination, a beam-type pumpingapparatus, a sucker rod line,'-and a load-limiting connection between' the beam and the sucker rod line including means forming an expansible chamber containing an expansible fluid through which lifting force is exerted on said sucker rod line, and means for confining so relatively large a-volume of expansible fluid under pressure in such substantially free communication with said chamber that any diminution of the size of said chamber. during lifting by said beam will not largelyincrease the chamber pressure, said ex- 7. In an apparatus of the character described, relatively reciprocable cylinder and piston elements; a connection with a substantial volume of fluid continuously underpressure expeeding atmospheric opening through the side of the cylinder element at a point spaced from one end thereof but in such proximity to said end that when said piston is at said end it completely occludes said 'side opening, and an opening communicating with atmosphere'for the influx and discharge of fluid relative to the other end ofsaid cylinder.

8. In an apparatus of the nature described, a cylinder, a piston therein, a connection with a substantial volume of gaseous fluidunder pressure exceeding atmospheric opening into one end otthe cylinder, and a lateral breather opening in the cylinder adjacent tobut spaced from the other end thereof, said opening being spaced in its entirety a distance less than the length of said piston from the other end of said cylinder.

RICHARD H. CARR. KENNETH A. COVELL. CHARLES F. 'IERRELL, JR.

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