US3292552A - Pumping apparatus - Google Patents

Description

Dec. 20, 1966 P, E, CHANCELLOR v ET AL 3,292,552

PUMPING APPARATUS Filed June e. i964 FORREST E. CHANCELLOR ROBERT O. CHANCELLOR 46 /NVENTORS MW U/J United States Patent 3,292,552 PUMIPING APPARATUS Forrest E. Chancellor and Robert 0. Chancellor, both of 2917 Pierce Road, Bakersfield, Calif. 93304 Filed June 8, 1964, Ser. No. 373,299 8 Claims. (Cl. 10S-155) The present invention relates to a pumping apparatus and more particularly to such a pumping apparatus which is highly effective for pumping uids of relatively high viscosity. While the apparatus of the present invention is shown and described as applied to oil wells, it will be apparent that the apparatus is not restricted to such operational environment.

Many problems are encountered when pumping oil of relatively high viscosity from a well, particularly if the well is deep so as to impose high power requirements, is prone to develop gas pockets, has a well lluid of high viscosity, or has a tendency to froth to an extent interfering with pumping elliciency. It is conventional practice to immerse a pump within the well duid by suspending the pump and its associated valving on a string of tubing. The tubing provides a fluid discharge passage from the well and accommodates a string of sucker rods connected to a iluid pumping cylinder or plunger within the pump. The string of sucker rods is usually power driven for reciprocation within the tubing from the surface of the well by a conventional rocker arm type reciprocator. In such conventional installations with the pump immersed within the well fluid, the plunger thereof must reciprocate in direct engagement with such iluid. The plunger usually has a traveling valve therein which permits lluid to flow upwardly through the plunger during its downstroke with the valve closing on the upstroke to pump such lluid displaced above the plunger outwardly of the well. However, when operating in such high viscosity oil, reciprocation of the plunger is retarded thereby so that during the downstroke the plunger is not permitted to fall as rapidly as the sucker rod string in the tubing. This retarding of the pump plunger on its return downstroke causes the reciprocator to place the sucker rod string in compression which results in premature termination of the plunger downstroke. Such operation results in reduced pumping elliciency, undue wear on the sucker rod string, and frequently complete failure under such compression forces.

The conventional pumping devices are also subject to gas locking wherein gas pockets frequently develop below the pump plunger which, when attempting to pass through the plunger on its downstroke, do not have suicient force to open the traveling valve in the plunger. Such condition requires that the pump and sucker rod string be disconnected from the reciprocator and lowered for bumping the pump against the standing valve in the tub- `ing for opening the traveling valve to permit the gas pocket to pass through the pump. A similar condition frequently occurs when pumping frothy oil having a relatively high gas content. Such conventional pumping devices are also adversely 'aifected by high discharge line pressures which may occur by :clogging or other restrictions therein which hold the traveling valve within the pump plunger closed to preclude the ow :of iluid therethrough.

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Various attempts have been made to solve such problems by attempting to alter the viscosity of the well uid. Such attempts have consisted of extending hot water or steam pipes into the well for heating the oil adjacent to the pump to reduce its specific gravity. Such piping is normally disposed outwardly of the tubing string requiring larger well casings. While such devices have been effective to reduce the viscosity of the oil for improved owability, the additional piping and heating apparatus in many pumping installations is not economically feasible.

The pumping structure disclosed in our Patent No. 3,044,414 entitled Deep Well Pumping System alforded another solution to the problem by providing a heavy weight on the lower end of the pump plunger to accelerate its downward movement through the high viscosity well lluid. This device, while operationally successful, incorporated certain inherent disadvantages which it has now been recognized could be eliminated to afford an improved structure for operating more efficiently in high viscosity fluids. While somewhat alleviating the viscosity problem, none of the prior art devices successfully overcomes the problems of gas lock and high discharge line pressures without creating other disadvantages which detract from efficient pumping operation.

Therefore, it is an object of the present invention to provide an improved well pumping apparatus for pumping well iiuid of relatively high viscosity.

Another object is to provide such an improved well pumping apparatus having a pump operable at optimum eflciency irrespective of the Viscosity of the well fluid.

Another object is to provide a well pumping apparatus lhaving a pump which is actuated by a sucker rod string,

which string is maintained in continuous tension during reciprocation.

Another object is to provide a well pumping apparatus of the character described which is readily adapted to slanted Well vholes without structural alteration of the pump.

Another object is to provide a well pumping apparatus which during operation is maintained substantially free of gas locks and is capable of pumping frothy oil having a relatively high gas content.

Another object is to provide a well pumping apparatus which is not materially affected by high discharge line pressures.

Another object is to provide a well pumping apparatus wherein the pump is capable of operating at an increase in strokes per minute over that which is possible in conventional pumping devices for increased well production.

Another object is to provide a well pumping apparatus which is capable of pumping such high viscosity lluids with no or a minimum increase in power needed to drive the pump.

Other objects and advantages of the present invention will subsequently become more clearly apparent upon reference to the following description in the specilication.

In the drawing:

FIG. 1 is a side elevation of a pumping apparatus embodying the principles of the present invention shown disposed within a well casing and driven through a sucker rod string by a reciprocator at the surface of the Well, the latter being shown at substantially reduced scale for illustrative convenience.

' FIG. 2 is a somewhat enlarged centralV longitudinal section through the well pumping apparatus of FIG. 1.

FIG. 3 is a fragmentary, further enlarged central longitudinal section through the valving portion of the pumping apparatus.

Referring more particularly to the drawing, a pumping apparatus generally indicated by the reference numeral is shown disposed Within a Well 11 having a casing 12 and containing a volume of well fluid 13, such as oil, 'having a relatively high viscosity. A power driven rod rreciprocator 14 is mounted on a platform 15 on the surface of the ground with the platform closing the top of the casing and providing a central aperture 16 therethrough concentrically of the casing. An elongated string of tubing 17 is suspended within the casing 12 by a flanged bushing 18 disposed in the aperture 16 in the platform. Thetubing terminates in a lowerrend 19 substant'ially below the level of well fluid 13. An elongated sucker rod string 20 is suspended from the reciprocator slidably through the bushing and downwardly within the tubing string in the well.

The pumping apparatus 10 provides an elongated pump barrel having an upper valve housing portion 27 and a relatively smaller diameter lower plunger housing portion 28. The upper valve housing portion 27 includes constricted upper Iand lower ends 30 and 32, respectively, which reduce to substantially the same diameter as the `'tubing string 17. The upper end 30 is screw-threadably connected to the lower end 19 of the tubing string by a collar 34. The upper portion 27 of the barrel and the tubing string thereby define a continuous fluid discharge passage from the .well 11. The lower plunger housing portion 28 of the pump barrel includes upper and lower ends 37 and 38, respectively, with the upper end bei-ng screw-threadably connected to the lower end 32 of the upper valve housing portion 27 by a collar 39. An elongated tubular shell 45 has a closed lower end 46 and an opposite upper end 47 screwthreada-bly connected to the lower end 38 of thelower plunger lhousing portion 28 of the pump barrel 25'by a collar 48.

An elongated tubular plunger 50 is slidably disposed Within the lower portion 28 of the pump barrel 25. The plunger provides an upper valve cage portion 51 having an axial valve bore 52 therein provided with a ciroumscribing seat 53. A spherical ball valve `55 of la diameter somewhat less than the diameter of the valve bore is disposed therein for engagement against the seat 53. The plunger is connected to the sucker rod string 20 for reciprocation therewith in alternate uid pumping and return suction strokes by an elongated .shaft 57 of a somewhat larger diameter thanthe sucker rod string. The shaft is screw-threadably connected at its lower end to the upper end of the valve cage portion of the plunger and at its upper end screw-threadably receives the lower end of the sucker rod string 20. A frusto-conical flange 59 is disposed in circumscribing relation about the shaft adjacent to its upper end for a purpose hereinafter to be described.

A iluid inlet valve 62 is mounted in the upper valve housing portion 27 of the pump barrel 25 upwardly adjacent to its lower end 32. The valve has an axial bore 64 therethrough of a diameter substantially larger than the diameter of the shaft 57 to form an elongated annular fluid passage 65 therebetween. A plurality of fluid inlet passages 67 are formed in the valve having outer nadifally disposed portions 68 and inner valve mounting portions 69 of a somewhat larger diameter. `A spherical ball valve 72 is loosely `mounted within each of the valve mounting portions 69 of the passagesv in axially sliding relation therein for engagementA with a seating Vring 73. The ball valves 72 `are constrained against axial displacement from the ball mounting portions 69 by perforate ball retainers 75 mounted on the upper ends of the valve.

A standing valve is disposed within the upper valve housing portion 27 in axially spaced relation to the inlet valve 62 adjacent to the upper end 30 of the upper housing portion 27 of the pump barrel 25. The valve includes a counterbore 82 within which is disposed a sleeve type bearing seal 84. The sleeve slidably embraces the shaft 57 in fluid sealing relation. An annular O-ring seal 85 is disposed within an annular groove 86 in the outer periphery of the sleeve intermediate its ends which compressibly engages the counterbore 82. The sleeve is axially constrained within the counterbore by a locking bushing 87 screw-threadably received into the counterbore at the lower end of the valve. The valve includes a plurality of axial bores or iluid passages 88 therethrough having enlargedv diameter upper ends 89 which individually receive ball valves 90 identical to the ball valves 72 of the inlet valves 62. rested against seating rings 91 in closing relation to the passages and are captured within their individual passages by perforate lball retaining members 92 mounted on the upper end of the valve.

A predetermined amount of nonviscous uid 94, such as water or the like, is disposed within the pump barrel 25 in partially `filling relation within the space between the plunger 50 and the inlet valve 62 to serve as a noncompressible, substantially nonrniscible force -t-ransmitting element between the plunger and well uid entering the barrel through the inlet valve 62. A similar nonviscous iluid 96 is disposed in substantially filling relation Within the shell 45.

Operation The operation of the described embodiment of the subject invention is believed to be clearly apparent and is brieily summarized at this point. The pumping apparatus 10 is substantially completely assembled at the surface of the earth above the well except for connecting the sucker rod string 20 to the .plunger shaft 57. The appara-tus is lowered into the well casing 12 in submerged relation within the well fluid 13 to a position closely adjacent to the bottom of the well, not shown, which may be several thousand feet below the surface of the ground. During such positioning of the pumping apparatus, the pump plunger 50 and shaft 57 are supported within the pump barrel 25 by engagement of the ange 59 with the upper end of the standing valve 80. The sucker rod string is then extended downwardly through the tubing string 17 and the connection between the lower end thereof and the shaft 57 is completed by appropriate rotation of the sucker rod string. The upper 'end of the sucker rod string is then connected to the reciprocator 14 which raises the plunger and shaft t the position shown in FIG. 2.

To begin the pumping operation, the reciprocator 14 is actuated to reciprocate the sucker rod string 20 and the pump plunger 50 in alternate upwardly traveling pumping and downwardly traveling return suction strokes. During each downstroke of the plunger, the pressure of the nonviscous uid 94 within the pump barrel'25 kbetween the plunger and the inlet valve 62 is lowered to provide a pressure differential between such chamber and the well fluid 13 externally of the barrel within the well casing `12. Such pressure kdilerential causes the ball valves 72 to be unseated and permits the well fluid to be drawn into the inlet passages 67 and to fill the pump barrel between the standing valve 80 and the plunger. It is important to note that the `hydrostatic head of then entire column of well uid in the casing 12 is exerted against the non-viscous Huid 94l which pressure is transmitted therethrough against the plunger for accelerating its downward movement ahead of the sucker rod string 20. Such downward force on the plunger is subsequently further augmented by the hydrostatic head pressure of the column of well fluid in the tubing string 17 being exerted against Ithe plunger shaft The valves 90 areV 57 and the ilange 59. Because of the relative densities of the high viscous well iluid 13 and the nonviscous uid 94, there is only slight intermixing therebetween so that during operation such high viscous well fluid never directly contacts the plunger as in conventional pumping devices. The non-viscous fluid 94 as well as the similar fluid 96 in the shell 45 further provide light lubrication of the plunger for substantially frictionless reciprocation within the barrel.

During the upstroke of the pump plunger 50, the trapped well fluid previously drawn into the pump barrel 25 is elevated, by upward movement of the nonviscous uid 94, through discharge passage 35 by way of the passage 65 in the inlet valve 62. The trapped Huid exerts a downward force against the ball valves 72 to dispose them in seating relation against their respective seating rings 73 to block reverse ow through the inlet passages 67. Concurrently, the trapped well fluid continues to be elevated through the discharge passage 35 by way of the passages 88 in the standing valve 80 with suicient force to open the ball valves 89 to permit upward flow of such well fluid into the tubing string 17 and outwardly of the well.

Also, during such upstroke of the plunger 50, the pressure of the nonviscous fluid 96 within the shell 45 is lowered with respect to the pressure of well fluid within the casing 12. The shell is preferably thirty feet in length so as to minimize the pressure differential or partial vacuum therein. It is noted that the downward force on the plunger imposed by such partial vacuum does not signilicautly retard plunger movement on its upstroke as the sucker rod string is then in tension and the reciprocator has an abundance of power readily to overcome such slight downward force. However, even though slight, such low pressure iiuid has a tendency to initiate return downward movement of the plunger on its downstroke. The bodies of nonviscous uid 94 and 96 thereby combine continually to urge the pump plunger downwardly within the barrel so as to maintain the sucker rod string in continuous tension and to lubricate the plunger as well.

It is furtherl signiiicant that during the above described operation the ball valve 55 within the plunger remains closed. The ball valve is only opened in the event that a sufficient quantity of the non-viscous fluid 94 leaks downwardly past the plunger into the body of uid 96 within the shell 45. If such leakage fills the shell and the lower portion of the barrel, the ball valve 55 is unseated during the plunger downstroke to bypass and return such accumulation of fluid upwardly into the body 94 of nonviscous iluid. Since the plunger and valve 55 are completely isolated from well iluid by the body of non-viscous iluid 94, gas pockets and high discharge line pressures have no adverse affect on pump operation as experienced with conventional pumping devices.

In view of the foregoing, it is readily apparent that the structure of the present invention provides an improved well pumping apparatus which enables the pump thereof to operate at maximum eciency irrespective of the viscosity of iluid within the well. The Huid inlet passages to the pump barrel are located above the pump plunger so that no well uid passes through the plunger as in conventional pumps and the hydrostatic head pressure of the well iluid entirely above the plunger is utilized to impose a downward force through the upper body of non-viscous fluid on the plunger. Such force positively propels the plungerdownwardly on its return suction stroke ahead of the sucker rod string so as to maintain the sucker rod string under continuous tension. Furthermore, the pump plunger is completely isolated from the well fluid and is reciprocated within the upper and lower bodies of non-viscous uid which maintain such separation of the plunger from the well uid and act as a lubricant for the plunger for substantially frictionless reciprocation.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A well pumping apparatus, for a well having a uid therein, an elongated string of tubing extended into such fluid in the well, and a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel connected to said tubing string and immersed within the fluid in the well, said pump barrel and tubing string providing a iluid discharge passage from the well; a plunger mounted in said barrel and connected to said sucker rod string for reciprocation therewith in alternate fluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well iluid therepast; rst valve means disposed within said barrel in upwardly spaced relation to the plunger alternately to open permitting ilow of well fluid therethrough into the discharge passage during said return suction stroke of the plunger and to close blocking reverse ow of well iiuid therethrough under uid pressure in the discharge passage during the pumping stroke; second valve means disposed within said luid discharge passage in upwardly spaced relation to said rst valve means alternately to open said discharge passage under iluid pressure therebelow during said pumping stroke and to close blocking reverse ow therethrough under weight of uid in the discharge passage during said return stroke, and force transmitting means disposed within said barrel between the plunger and said first valve means so as substantially to isolate the plunger from said well fluid in the discharge passage.

2. A well pumping apparatus, for a well having a fluid therein, an elongated string of tubing extended into such uid in the well, and a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel connected to said tubing string and immersed within the fluid in the well, said pump barrel and tubing string providing a fluid discharge passage from the well; a plunger mounted in said barrel and connected to 4said sucker rod string for reciprocation therewith in alternate uid pumping and return suction strokes; rst valve means disposed within said barrel in upwardly spaced relation to the plunger alternately to open permitting ow of well fluid therethrough into the discharge passage during -said return suction stroke of the plunger and to close blocking said reverse flow of well uid therethrough under iluid pressure in the discharge passage during the pumping stroke; second valve means disposed within said iluid discharge passage in upwardly spaced relation to said iirst valve means alternately to open said discharge passage under fluid pressure therebelow during said pumping stroke and to close blocking reverse flow therethrough under weight of fluid in the discharge passage during said return stroke, and plunger biasing means mounted on said barrel below the plunger to facilitate movement thereof during said return stroke.

3. A well pumping apparatus, for a well having a uid therein, an elongated string of tubing extended into such fluid in the well, and a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel connected to said tubing string and immersed within the Huid in the well, said pump barrel and tubing string providing a fluid discharge passage from the well; a plunger mounted in said barrel and connected to said sucker rod string for reciprocation therewith in alternate fluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well uid therepast; a uid inlet valve disposed within said barrel in upwardly spaced relation to the plunger alternately to open permitting flow of well iluid therethrough into the discharge passage during said returnY suction stroke of the plunger and to close blocking reverse flow of well iluid therethrough under fluid pressure in the discharge passage during the pumping stroke; a standing valve disposed within said fluid discharge passage an upwardly spaced relation to said inlet valve alternately to open said discharge passage under fluid pressure therebelow during said pumpingstroke and to close blocking reverse llow therethrough under weight of fluid in the discharge passage during said return stroke; a force transmitting element disposed within said barrel between the plunger and said inlet valve so as substantially to isolate the plunger from said well fluid in the discharge passage; and plunger biasing means mounted on said barrel below the plunger to facilitate movement thereof during said return stroke.

4. A well pumping apparatus, for a well having a iluid therein, an elongated string of tubing extended into such lluid in the well, and a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel connected to said tubing string and immersed within the lluid in the well, said pump barrel and tubing string providing a fluid discharge passage from the well; a plunger mounted in said barrel and connected to said sucker rod string for reciprocation therewith in alternate lluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well iluid therepast; a iluid inlet valve disposed within said barrel in upwardly spaced relation to the plunger alternately to open permitting tlow of well fluid therethrough into the discharge passage during said return suction stroke of the plunger and to close blocking reverse flow of well iluid therethrough under lluid pressure in the discharge passageV during the pumping stroke; a standing valve disposed within said lluid discharge passage in upwardly spaced relation to said inlet valve alternately to open said discharge passage under fluid pressure therebelow during said pumping stroke and to close blocking reverse flow therethrough under weight of fluid in the discharge passage during said return stroke; a force transmitting element disposed within said barrel between the plunger and said inlet valve so as substantially to isolate the plunger from said well lluid in the discharge passage; enclosure means downwardly extended from the barrel; and plunger biasing means disposed within said enclosure means below the plunger to facilitate movement thereof during said return stroke.

5. A well pumping apparatus, `for a Well having a fluid therein, an elongated string of tubing extended into such uid in the well, a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel having an upper end connected to said tubing string and immersed within the fluid in the well and an opposite lower end, said pump barrel and tubing string providing a fluid discharge passage from the well; a plunger slidably disposed within said barrel adjacent to said lower end thereof and connected to said sucker rod string for reciprocation therewith in alternate fluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well fluid therepast; valve means disposed within said barrel intermediate its ends in upwardly spaced relation to the plunger alternately to open and to block llow of well fluid therethrough in said discharge passage incident to reciprocation of the plunger; force transmitting means disposed withinsaid lluid discharge passage between the plunger and said valve means so as substantially to isolate the plunger from well fluid therein; an elongated imperforate tubular shell connected to said lower end of the barrel and downwardly extended therefrom in closing relation to said lower end; and plunger biasing means disposed within said shell for movement with the plunger to facilitate downward travel of the plunger during said return stroke.

6. A well pumping apparatus, for a well having a uid therein, an elongated string of tubing extended into such uid in the well, a sucker rod string disposed in the tubing for reciprocation therein, comprising a pump barrel having an upper end connected to said tubing string and immersed within the tluid in the well and an opposite lower end, said pump barrel and tubing string providing a fluid discharge passage from the well; a plunger slidably disposed within said barrel adjacent to said lower end thereof and connected to said sucker rod string for reciprocation therewith in alternate lluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well lluid therepast; valve means disposed within said barrel intermediate its ends in upwardly spaced relation to the plunger alternately to open and to block flow of well fluid therethrough in said discharge passage incident to reciprocation of the plunger; a force transmitting nonviscous fluid disposed within said barrel between the plunger and said valve means to lubril ing for reciprocation therein, comprising a pump barrel` having an upper end connected to said tubing string and immersed within the fluid in the well and an opposite lower end, said pump barreland tubing string providing a lluid discharge passagerfrom the well; a plunger slidably disposed within said barrel adjacent to said lower end thereof and connected to said sucker rod string for re,-`

ciprocation therewith in alternate fluid pumping and return suction strokes with the plunger substantially sealing the barrel to passage of well fluid therepast; valve means disposed within said barrel intermediate its ends in up wardly spaced relation to the plunger alternately to open and to block llow of well iluid therethrough in said discharge passage'incident to reciprocation of the plunger; a force transmitting body of nonviscous lluid disposed within said iluid discharge passage between the plunger,

and said valve means to lubricate and substantially to isolate the plunger from well lluid therein; an elongated imperforate tubular shell connected to said lower end of the` barrel and downwardly extended therefrom in closing relation to said lower end; and a body of nonviscoustluid disposed within said shell for movement with the plunger to lill the space vacated thereby creating a partial vacuum within said shell during said pumping stroke to facilitate downward travel of the plunger dnringsaid return stroke.` 8. A well pumping apparatus for a well having a vis.

cous fluid therein comprising an elongated barrel adapted to be immersed within the fluid of the well and having upper and lower ends; a plunger mounted in the barrel for reciprocation longitudinally thereof in alternate upwardly traveling fluid pumping and return downwardly traveling suction strokes with the plunger substantially sealing the barrel to passage of well lluid therepast; an elongated tubing string connected to said upper end of the barrel and upwardly extended from the well, said tubing string and said upper end of the barrel defining a fluid discharge passage for well lluid, said barrel having a fluid admitting port in the well tluid intermediate its ends and above said plunger; means for reciprocating the plunger in the barrel; an inlet valve disposed in the barrel above the plunger adapted to close said port under uid pressure within the discharge passage during the pumping stroke of the plunger and to open under the weight of lluid in the well externally of the barrel during the Suction stroke of the plunger; a standing valve in the barrel within the discharge passage in upwardly spaced relation to the inlet valve adapted to close under weight of fluid in the discharge passage during the return suction stroke of the plunger and to open under uid pressure therebelow within the discharge passage during the pumping stroke of the plunger; a body of nonviscous fluid disposed within said barrel between the plunger and said inlet valve to lubricate and substantially to isolate the plunger from well uid in said discharge passage; an elongated imperforate tubular shell connected to said lower end of the barrel and downwardly extended therefrom in closing relation to said lower end; and a body of nonviscous iluid 10 disposed within said shell for movement with the plunger during its pumping stroke to lill the space vacated thereby for creating a partial vacuum within the shell to facilitate said downward travel of the plunger during said return stroke.

References Cited by the Examiner UNITED STATES PATENTS Lewis 103-155 Montgomery 103-155 ONeil 103-206 ONeil 103-206 Martin 103-156 Francis 103--155 Sutlii 103--155 DONLEY I. STOCKING, Primary Examiner.

WARREN E. COLEMAN, LAURENCE E. EFNER,

Examiners.

Claims (1)

1. A WELL PUMPING APPARATUS, FOR A WELL HAVING A FLUID THEREIN, AN ELONGATED STRING OF TUBING EXTENDED INTO SUCH FLUID IN THE WELL, AND A SUCKER ROD STRING DISPOSED IN THE TUBING FOR RECIPROCATION THEREIN, COMPRISING A PUMP BARREL CONNECTED TO SAID TUBING STRING AND IMMERSED WITHIN THE FLUID IN THE WELL, SAID PUMP BARREL AND TUBING STRING PROVIDING A FLUID DISCHARGE PASSAGE FROM THE WELL; A PLUNGER MOUNTED IN SAID BARREL AND CONNECTED TO SAID SUCKER ROD STRING FOR RECIPROCATION THEREWITH IN ALTERNATE FLUID PUMPING AND RETURN SUCTION STROKES WITH THE PLUNGER SUBSTANTIALLY SEALING THE BARREL TO PASSAGE OF WELL FLUID THEREPAST; FIRST VALVE MEANS DISPOSED WITHIN SAID BARREL IN UPWARDLY SPACED RELATION TO THE PLUNGER ALTERNATELY TO OPEN PERMITTING FLOW OF WELL FLUID THERETHROUGH INTO THE DISCHARGE PASSAGE DURING SAID RETURN SUCTION STROKE OF THE PLUNGER AND TO CLOSE BLOCKING

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