US2628563A - Fluid-operated pump with double-acting direct-connected booster pump - Google Patents

Description

Feb. 17, 1953 c. J. coBERLY 2,628,563

FLUID-OPERATED PUMP WITH DOUBLE-ACTING DIRECT-CONNECTED BOOSTER PUMP Filed Feb. 2l, 1949 2 SHEETS-SHEET l Patented Feb. 17, 1953 FLUID-OPERATED PUMP WITH DOUBLE-- ACTING' DIRECT-CONNECTED BOOSTER PUMP Clarence J. Coberly, Pasadena, Calif., assignor, by mesne assignments, to Dresser Equipment Company,V Cleveland, Ohio, a corporation of Ohio Application February 21, `194:9, 4Serial No. 77,588

(CL 10S-5) 9-Claims.

l M-y invention relates to .duid-operated pumps for wells, and, more particularly, to a fluid-opy erated pumping device comprising a fluid-operated main pump having an auxiliary or booster pump associated therewith for increasing the pressure of the Well uid delivered to the inlet of the main pump above that obtaining at the intake of the booster pump.

Fluid-operated pumps are commonly used in the oil industry for pumping oil from wells, such a pump comprising, in general, a coupled motor and pump combination set in the well at the level from which oil is to be pumped. In such a combination, the motor comprises a motor piston which is actuated by alternatively admitting an operating fluid, such as clean crude oil, under relatively high pressure into opposite ends of a motor-cylinder in which the motor piston is disposed so as to reciprocate the motor piston. The reciprocating motion of the motor piston is communicated to a pump piston in the pump section of the combination so that the pump piston pumps ol from the Well.

The fluid being pumped from la Well may contain, in addition to oil, various other fluids such as Water and natural gas, the gas being present in solution or in suspension in the oil in varying quantities depending upon the pressure and temperature conditions prevailing i-n the well. Also, if the Well is being pumped beyond its capacity to produce, air may be present in the iluid being pumped. If the oil is saturated or super-saturated With natural gas at the conditions of pressure and temperature prevailing at the level at which the pump is set, a large portion of the gas may be released during the suction stroke of the pump piston to form a gas pocket in the pump cylinder. Also, of course, in many Wells the well fluid is merely a froth composed largely of gas with a relatively small volume of oil. In either case, or if air is drawn into the pump cylinder, a pocket of gas or air in the pump cylinder results, Such pockets result in a material reduction in the pumping load until such time as the pump piston compresses the gas or air present and strikes solid Well fluid in the cylinder.

Such fluid-operated pumps are frequently set at relatively great depths and, consequently, a large volumel of operating fluid under relatively high pressure is conned in the supply tubing between the pump in the well and the apparatus n the surface which delivers the operating iluid to the pump. Due to the appreciable compressibilitz.r of vthis large volume of operating'iiuid, and due tothe expansion of the supply tubing under the relatively high pressure at which rvthe'operating fluid is maintained, a large amount ofenergyis stored under normal operating conditions. If, because of the presence of gas or air in the pump cylinder, the load on the pump piston decreases, a sudden increase in therate of 'iiow of operating fluid to the pump occurs, 'thereby accelerating the motor and pump pistons. IIlhe speed ultimately attained may be 'excessive and the pump may race for a portion of a strokeyor for a number of strokes, which is normally detrimental to various components of the pump. Various expedients for preventing damage to the pump mechanism under such conditions have been employed. For example, oW regulators Adisposed in the supply line for vthe operating 'fluid have been employed to maintain the rate vof delivery of operating Iluid to the motor section of the pump below a value which might be harmful to the pumping equipment. While such rflow governors are practical under most conditions of operation, they have some disadvantages 'in that they increase the cost of the pumping equipment and render the equipment rather complicated. Also, there is some lag in their operation lsince they respond only after the condition requiring compensation has already developed.

Also, the presence of gas or air in the pump cylinder has a detrimental effect on the efllciency of such a duid-operated pump. For example, if, in a given installation, thirty percent of the 4pump cylinder of the duid-operated pump contains free gas or air, the efiiciency of the pump, i. e., the percentage of the volume of the pump cylinder which contains solid Well fluid, Will be only seventy percent. In other Words, under such conditions, the duid-operated pump Will pump well iiuid from the Well at only seventy percent of capacity.

In View of the lforegoing considerations, it is a primaryv object of the present invention to provide, in combination with a conventional fluidoperated pump, an auxiliary or booster pump which is adapted to draw Well uidirom the well and toV deliver it to the inlet of the fluid-operated pumpy at lan increased pressure such that the major portion of the gas or air in the well fluid will not flash out to form a pocket in the pump cylinder of the main pump. I accomplishY this by providing a booster pump which Will maintain the pressure of the Well fluid passing int-o the pump cylinder of the ma-inxpump` ata 'value equal to orabove the.pressureprevailingfin the well at the inlet of the .pumpingdevice. A-,further object yof the invention; is to provider a.

3 booster pump which will compress any free gas or air entrained in the well fluid to a substantial extent before it is delivered to the inlet of the main pump.

It will be apparent that employing a booster pump in combination with a huid-operated main pump in the foregoing manner will obviate, or at least minimize, the difficulties hereinbefore discussed. In other words, the employment of a booster pump will tend to obviate the racing of the main pump and to increase the pumping eiiiciency thereof. As an example, let it be assumed that the pumping efficiency of the main pump is only seventy percent when the pressure at the inlet thereof is approximately equal to atmospheric pressure. With the present invention, if the particular booster pump utilized is adapted to increase the pressure of the well fluid delivered to the inlet of the main pump to three hundred pounds per square inch, the free gas or air which otherwise would occupy thirty percent of the volume of the pump cylinder of the main pump will be compressed to occupy only approximately 1.4 percent of the volume of the pump cylinder, thereby increasing the efliciency of the main pump to approximately 98.6 percent under such conditions.

Another object of the present invention is to provide such a pumping device, i. e., such a fluidoperated main pump and booster pump combination, in which the booster pump is directly connected to the main pump so as to be operable thereby. More specifically, it is an object to provide a duid-operated pumping device wherein the booster pump includes a booster pump piston i directly connected by rod means to one of the pistons of the main pump, preferably the pump piston thereof.

A further object of the invention is to provide in such a pumping device a booster pump of the double-acting type so as to maintain substantially constant pressure at the inlet of the main pump.

Another object is to provide such a pumping device wherein the main and booster pumps are removable as a unit.

Still another object is to provide a pumping device of the character mentioned wherein the main and booster pumps are insertable into a tubular receiver which provides a seat.

A further object is to provide a booster pump having pressure relief valve means for by-passing fluid discharged by the booster pump piston to the well in the event that the pressure of the fluid delivered to the inlet of the main pump tends to exceed a predetermined value.

Another object of the invention is to provide a. pumping device wherein the rod means connecting the various pistons of the main and booster pumps is hydraulically balanced with respect to operating fluid pressure.

The foregoing objects and advantages of the present invention, together with various other objects and advantages thereof which will become apparent, may be attained through the employment of the exemplary embodiment of the invention which is illustrated in the accompanying drawings and which is described in detail hereinafter.

Referring to the drawings:

Fig. 1 is a utility view on a reduced scale showing a fluid-operated pumping device which embodies the invention as installed in a well;

Fig. 2 is a longitudinal sectional view of the upper-end of a preferred booster pump of the invention and is taken along the broken line 2-2 of Fig. 1 of the drawings;

Fig. 3 is a downward continuation of Fig. 2 and is taken along the broken line 3--3 of Fig. l;

Fig. 4 is a downward continuation of Fig. 3 and is taken along the broken line 4-4 of Fig. 1;

Fig. 5 is a tranverse sectional view taken along the broken line 4-4 of Fig. 2; and,

Figs. 6 and 7 are transverse sectional views respectively taken along the broken lines 6-6 and 'I-I of Fig. 4.

Referring particularly to Fig. 1 of the drawings, I show an oil well lined with a casing I0 having perforations II which register with an oil producing formation through which oil and other fluids may flow into the interior of the casing, the fluids entering the casing being collectively referred to hereinafter as the well fluid. Extending downwardly into the casing I0 is a production tubing I3 which is adapted to convey well fluid to the surface of the ground, and extending downwardly into the production tubing in the particular construction illustrated is a power tubing I4 having a fluid-operated main or primary pump I5 connected to the lower end thereof. Connected to the lower end of the main pump I5 is an auxiliary or booster pump I6 which is adapted to pump well fluid from the casing I0 to the inlet of the main pump at a pressure higher than that obtaining at the intake of the booster pump, as will be discussed in more detail hereinafter. The main and booster pumps I5 and I6 extend into a tubular receiver I1 which, in effect, forms an extension of the production tubing I3 and which is secured to the lower end thereof, the main and booster pump assembly seating on a tapered seat I8 at the lower end ot the receiver Il, as shown in Fig. 4 `of the drawings.

The fluid-operated main pump I5 may 4be of any conventional type, such as that shown in my Patent No. 2,081,220, issued May 25, 1937, which is adapted to pump well fluid from the casing I0 upwardly through the production tubing I3 to the surface. As shown diagrammatically in dotted lines in Fig. l of the drawings, the fluidoperated main pump I5 is provided with a motor cylinder 2| having a motor piston 22 therein, and is provided with a pump cylinder 23 having a pump piston 24 therein, the motor and pump pistons respectively being provided with longitudinal passages 25 and 26 therethrough. Connected to the upper end of the motor piston 22 and communicating with the passage 25 therethrough is an upper tubular rod 21. Connecting the motor and pump pistons 22 and 24 and communicating with the respective passages 25 and 26 therethrough is an intermediate tubular rod 29, and connected to the lower end of the pump piston is a lower tubular rod 30 for directly connecting the main pump I5 to the booster pump I6 as will be discussed in more detail hereinafter.

Briefly, the fluid-operated main pump I5 operates as follows: operating fluid, such as clean crude oil, under relatively high press-ure is alternately admitted into opposite ends of the motor cylinder 2| to reciprocate the motor piston 22 therein, such reciprocatory motion of the motor piston being communicated to the pump piston 2-4 by the intermediate tubular rod 29. The pump piston 24 discharges fluid into the production tubing I3, which conveys the uid upwardly to the surface.

Considering the pumping device in more detail, the tubular receiver Il, which, as previously indicated, is connected to the lower end of the production tubing I3, includes a plurality of Icomponents, one of these being a tubular coupling 33 which is threaded onto the lower end of the production tubing, as bestshovvn in Fig. 2 of the drawings. Threadedv into the coupling 33 is a sleeve 34 and threaded onto this sleeve is `another tubular coupling 35 havin-g a portion olf reduced diameter which is threaded into a tubular -intake iitting 36, as lbest shown in Fig. 3 of the drawings. Threaded onto the lower en-dof the intake iitting 38 is a sleeve 31 and, as best shown in Fig. 4, threaded into the lower end of this sleeve is another tubular intake fitting 3B. Another sleeve 39 is threaded into the lower end lof the intake fitting 38 and threaded ont-o the lower end of the sleeve 39 is a tubular pump seat member 43 which provides the previously mentioned pump sea-t I8.

Referring to Fig. 2 of the drawings, the main pump I5 terminates at its lower end in a tubular inlet and discharge fitting 43 which is of smaller diameter than the internal diameter of the production tubing I3 to provide an annular space 44 through which wel-l iiuid discharged lby the main pump may flow upwardly. The annular space 44 is closed at its lower end when the main and booster pumps I5 and I8 are in their operating positions by a sealing ring 45 which is carried in an annular groove 45 in the fitting 43 and which is adapted for uid-tight engagement with va sleeve 41 pressed into the tubular' coupling 33. Well fluid discharged by the main pump I5 enters the annular space 44within the production tubing I3 through discharge passages 48 in the fitting 43, only one of these ydischarge passages being visible in Fig. 2 of the drawings. The iitting 43 is also 'provided `with longitudinal passages which serve las inlet ports 49 for the main plump I5, these inlet ports being shown Kbest in Fig. 5 olf the drawings.

Considering the booster pump I6 in more detail, it includes a tubular fitting 52 which is seated against the lower end of the tting 43, the ttings 43 and 52 respectively being provided with registering annular grooves 53 and 54 which communicate with the inlet ports 49 in the iitting 43. The tting 52 is provided with a plurality of longitudinal passages 55 therethrough, only one of which is visible in Fig. 2 of the drawings, which also communicate with the registering annular grooves 53 and 54.

Seated against'the lower end of the fitting 52 is a tubular iitting 58 having a stem 59 which is threaded into the tting 52. Also seated against the lower end of the iitting 52 is another tubular tting 60 having an internal diameter which is greater than the external diameter of thewtting 53 tok provide an annular passage 6I therebetween, the passage 6I communicating with the lower ends of the longitudinal passages 55 through the tting 52.

Seated against the lower end of the iitting 60 is la tubular discharge B2 having a plurality of longitudinal passages 63 therethrough which communicate at their upper ends with the annular passage 6I, the passages 63 being regarded as discharge ports for the booster pump I6 as will be discussed in more detail hereinafter. A sleeve 64 encloses the fittings' 52 and 80 and is threaded at its ends onto the fittings 43 and 62 to clamp the fittings 43, 52, 6G and 62 together.

Referring particularly to Fig. 3 of the drawings, threaded'onto the lower end of the discharge iitting'62 is a booster pump cylinder 61. The external diameter of the booster pump cylinder approachesthe internal diameters of themtake fittings 36 f andA 38 .so yas to make ysubstantially fluid-tight contact therewith,.but isislightly less than the internal diameters of they intake fittings so as tor permit insertion ofl the'booster pump I6 into and withdrawalth'ereof from the tubular'receiver I1.

Threaded into the lowerV end of the booster pump cylinder 61' isia tubular tting and connected to the' lower end of this fitting by acoupling 69 is. a. member 10 having a tapered external surface 1I which is adapted to engage the pump seat I8 to support the main and booster pumps I5 and I6. l

Referring particularly to Figs. Zand 3 ofthe drawings, the lower tubularV rod 30 ofi the'` main pump I5 extends downwardly from thelpump piston 24 ofthe main pump through the` tubular fittings 43.5258 and 62v into the booster pump cylinder. 81 wherein it is threaded into a tubular booster pump piston 15,Y suitable packings 16 and 11 respectively'being provided between the rod 30 and the fittings 43,152 andbetween therod: 30 and the ttings 82. As best shown in Figs. 3 and 4 of the drawings, a tubular rod 18 isthreaded into the lower end of the tubular pumpy piston 15 and projects from the lower end of the booster pump cylinder 61 through the tubulartting 68 into a balance chamber 19 which is threaded into theV iitting 68, suitable packing being provided between the rod 18 and thefitting 68.

It will be apparent that with thisconstruction, the main and booster pumps I5 and I6 are hydraulically balanced insofar as the transverse rod areas are concerned, the upper end of the upper tubular rod 21 of the ymain pump being exposed to operating iiuid pressure in theipo'wer tubing I4, as shown in. Fig. lof the drawings, and the lower end of the tubular rod 18 being exposed to operating iluid Ypressure in the balanceA chamber 18, as shown in Fig. 4 of the drawings. Operating fluid enters the balance chamber 19 through the upper tubular rod 21, the passage 25 through` the motor piston 22 of the main pump, the intermediate tubular rod 29, the passage 26 through the pump piston 24 of the main pump, the lower tubular rod 30, the tubular booster pump piston 15 and the tubular rod 18.

Considering the booster pump piston 15 in more detail and referring particularly to Fig. 3

of the drawings, it includes a tubular core4 83 into which the tubular rods 30 and 18 areV threaded, this core having an external ange 84 thereon intermediate its ends. Seated. against opposite sides of the ange 84 are oppositely .disposed packing cups 85 whichare formed of a'exible and resilientmaterial suchas' leather. oil-resistant rubber, or the like. Extending into and seated against the base wall of each packing cup 85 is a spacer 86 and seated againsteachl spacer 85 is a packing cup 81, the packing cups' 81 being oppositely disposed and. being identical Ato the packing cups 85'. Extending intoiand seated against the base walls of the packing cups 81 are spacersv 88,'the latter being engaged rby` nuts 89 threaded on the ends of the cores 83 to Yhold the components of theboos'terpump piston in assembled relationship.

Referring particularly to Fig. 3 of the :drawings, threaded into thetubulariitting 62 at the upper end of the booster pump'cylinder 61 and encircling the rod 30 is a sleeve 92 and threaded onto this sleeve is yan insert 93 which is embedded in an kintake lvalve '94 of the cup' type, the intake valve being formed of ainexibieand resilient nia-- terial. Preferably, the valve 94 is formed of a rubber-like material of an oil-resistant nature, such as neoprena for example. The intake valve 94 is provided with a skirt which is adapted to close intake ports 95 in the booster pump cylinder 61 when the pressure within the booster pump cylinder exceeds that in the intake ports and which is adapted to be deformed inwardly to open the intake ports when the pressure in the cylinder 61 is reduced below that in the intake ports. The intake ports 95 communicate with an internal annular groove 96 formed in the upper intake fitting 36, the groove 96 in turn communicating with the well through intake ports 91 in the tting 36.

The intake valve 94 is provided with a plurality of longitudinal passages therethrough which communicate with the discharge ports 63 through an annular space |0| between the fitting 62 and the valve 94. Disposed in the annular space IOI and encircling the sleeve 92 is a discharge valve |02 having projections |03 which are insertable into the passages |00 in the intake valve 94 to close them, the discharge valve being biased toward its closed position by a spring |04 which is seated against the lower end of the discharge tting 62. The spring |04 is adapted to permit the discharge valve |02 to open when the pressure in the booster pump cylinder 61 above the booster pump piston 15 exceeds the pressure in the discharge ports 63, and to close the discharge valve when such pressure is less than that in the discharge ports.

Referring now to Fig. 4 of the drawings, threaded into the tubular tting 68 at the lower end of the booster pump cylinder 61 is a sleeve |01 onto which is threaded an insert |08 embedded in an intake valve |00 which is identical to the intake valve 94, the intake Valve |09 controlling flow through intake ports I|0 in the booster pump cylinder. The intake ports ||0 communicate with an internal annular groove |I| in the lower intake tting 30, which groove in turn comunicates with the well through intake ports I |2 in the tting 38.

The intake valve |09 is provided with longitudinal passages |I5 therethrough which correspond to the longitudinal passages |00 through the intake valve 94 and which communicate with an annular space |I6 between the tting 68 and the intake valve |09. Disposed in the annular space |I6 and encircling the sleeve |01 is a discharge valve ||1 having projections IIB which are insertable into the longitudinal passages I|5 to close them, the discharge valve I1 being identical to the discharge valve |02 and being biased toward its closed position by a spring II9 which is seated against the fitting 68.

Referring to Figs. 4 and 7 of the drawings, communicating with the annular space |I6 containing the discharge valve ||1 is a plurality of radial ports |22 in the booster pump cylinder 61, these ports communicating with an annular groove |23 in the lower intake itting 30. Formed in the tting 38 and communicating at their lower ends with the annular groove |23 are longitudinal passages |24 which, as best shown in Figs. 3 and 4 of the drawings, communicate at their upper ends with an annular passage |25 between the sleeve 31 of the tubular receiver I1 and the booster pump cylinder 61. rIhe annular passage |25 communicates at its upper end with the lower ends of longitudinal passages |26 in the upper intake fitting 36, the passages |26 communicating at their upper ends with an annular 8 groove |21 in the fitting 36. The groove |21 communicates with the annular space |0I containing the discharge valve |02 through radial ports |28 in the booster pump cylinder 61.

Considering the operation of the booster pump I6, during the upward stroke of the motor and pump pistons 22 and 24 of the main pump I5, the booster pump piston 15 is moved upwardly in its cylinder 61 by the rod 30, the booster pump piston being shown in its uppermost position in Fig. 3 of the drawings. During its upward stroke, the booster pump piston 15 discharges well fluid contained in the cylinder 61 thereabove into the annular space |0I containing the discharge valve |02, the discharge valve unseating to permit this to occur. Outow into the well through the intake ports is prevented by the skirt of the cup-type intake valve 94. From the annular space I0 I, the well duid discharged by the booster pump piston 15 enters the discharge ports 63 and ultimately reaches the inlet ports 49 of the main pump I5 through the previously-described intervening passages.

Also during the upward stroke of the booster pump piston 15, well fluid is drawn into the booster pump cylinder 61 beneath the piston through the intake ports I I2, the annular groove I I I and the intake ports I I0, the skirt of the cuptype intake valve |09 deforming inwardly to permit this to occur. At the same time. the discharge valve I I 1 closes the longitudinal passages H5 through the intake valve |09.

During the downward stroke of the motor and pump pistons 22 and 24 of the main pump I5, the rod 30 moves the booster pump piston 15 downwardly in its cylinder 61. During its downward stroke, the booster pump piston 15 discharges well fluid contained in the cylinder 61 therebeneath through the longitudinal passages H5 in the intake valve |09 and into the annular space ||6 containing the discharge valve II1, the discharge valve ||1 opening to permit this to occur. During the downward stroke of the booster pump piston 15, the intake valve |09 closes the intake ports I I0 to prevent outiiow into the well. From the annular space II6, the well fluid discharged during the downward stroke of the booster pump piston flows upwardly to the discharge ports 63 by way of the radial ports |22 in the booster pump cylinder 61, the annular groove |23 in the intake fitting 38, the longitudinal passages |24 in this fitting, the annular passage |25 between the sleeve 31 and the booster pump cylinder, the longitudinal passages |26 in the intake fitting 36, the annular groove |21 in this fitting and the radial ports |20 in the booster pump cylinder. From the discharge ports 63 the uid discharged during the downward stroke of the booster pump piston 15 ows upwardly through the previously-described intervening passages to the inlet ports 49 of the main pump I5.

Thus, by discharging well uid on both strokes of the booster pump piston 15, the booster pump I6 delivers well uid to the inlet ports 49 of the main pump I5 at a substantially constant rate and at a substantially constant pressure, which is an important feature of the invention.

Referring particularly to Fig. 4 of the drawings, the booster pump I6 includes pressure relief valve means |35 for by-passing duid discharged by the booster pump piston 15 into the well in the event that the pressure of the well fluid delivered to the inlet ports 49 of the main pump I5 exceeds a predetermined value. The pressure relief valve means |35 is ycarried by `the member 'I0 which is seated on the pump seat I8 and includes a ball valve |36 carried by a retainer |31 and urged into engagement with a seat |38 by a spring |39'.v The seat |38 encircles a passage |40 which communicates with a vrecess |4I in the member "Id, the fitting 6B being provided with longitudinal passages |42 which connect the recess |4I to the annular space I i6 containing the discharge valve III. The member I is also provided with radial passages |43 which connect the recess I4i toan annular passage |44 between the booster pump I6 and the tubular receiver I'I, the annular passage |44 communicating at its upper end with the annular groove |23 in the fitting 38. Thus, well duid discharged by the booster pump piston 'I5 may flow into the passage |40 controlled by the ball valve |36 through the longitudinal passages |42 in the fitting 68, or through the .annular passage |44.

In the event that the pressure .of the well fluid discharged by the booster pump piston l rises above a predetermined value for any reason, the spring |38 is compressed toA permit the 'ball valve |36 to unseat, thereby permitting fluid to flow through the passage |40 into a recess |45 containing the ball valve |36, the retainer |31 and the spring |39. The member is providedwith radial passages |46 through which uid may flow from the recess |45 into the well upon unseating of the ball valve |36. I

Thus, the auxiliary or booster pump I6 delivers well duid to the inlet ports 49 of the fluid-operated main pump I5 at an elevated pressure to minimize the formation of gas or air pockets in the pump cylinder 23 of the main pump, whereby to increase the eiciency of the main pump and to minimize'the possibility of damage to the components thereof which may result from the formation of gas or air pockets in the pump cylinder 23 as Apreviously discussed. The booster pump I6 preferably delivers a relatively large volume .of well fluid to the main pump at a relatively low pressure, the effective cross sectional area .of ythe booster pump piston 'I5 being substantially larger than that of the motor piston 22 of the main pump to accomplish this. In practice, the ratio of booster pump piston area to motor piston area may be four to one, for example. Thus, the major portion of the work necessary to pump well fluid to the surface is performed by the main pump I5, the function of the booster pump I6 being to deliver the well uid to the main pump at a pressure sufficient only to prevent excessive formation of gas pockets in the pump cylinder 23 of the main pump, which pressure preferably exceeds the pressure obtaining at the intake ports 95, 9i and IIB, |I2 of the booster pump.

In the event that the pressure developed by the booster pump I6 rises above the value determined by the spring |39 of the pressure relief valve means |35 for any reasons, the ball valve |36 will unseat to by-pass fluid to the well, as hereinbefore discussed.

As will be apparent, the main pump I5 and the booster pump I6 may be installed in or removed from the well as a unit, the booster pump being slidably positioned in the tubular receiver II. As hereinbefore discussed, when the main and booster pumps are in their respective operating positions with the booster pump in engagement with the pump seat I8, the sealing ring 45 carried by the main pump provides a fluid-tight seal between the main and booster pumps.

Although I have disclosed an exemplary embodiment of the inventionv for purposes ,Ofjillus tration, it will be understood that various changes, modifications and substitutions maybe incorporated in the specific embodiment' 4dis"- closed without necessarily departing 'from the spirit of the invention and I hereby" reserve .the right to all such changes, modifications and substitutions.

I claim as my invention:

1. In a fluid-operated pumping device, the combination of: ,a fluid-operatedmain pump"Y of. the reciprocating type a'clap'tedto be ppsi'tidnd in a well and to pump well fluid fromtie' ,Well to the surface, said main. pump being" provided with an inlet port.; a double-acting auxiliary pump of the reciprocating vtype' provided'lWith intake port means which is vadapted'to come municate with the well and provided, with rdisgcharge port means; means providing a LIgised,V communieatinjg pressure-maintaining` passage only with said inlet port and 'saiddiseharge' `port means so as to maintain rfluid'pressure in said inlet port substantially .equal to that in saiddischarge port means; .and means mechanically connecting said auxiliary pumpk to said main pump lfor operating said auxiliary pump so as to pump well fluid from the well to said'inlet port at a `pressure higher than .that in said'jintafke' port means.

2. In a fluid-operated pumping device, the combination of: auid-operatedpmain Dump' of the reciprocating type adapted'to Depositioned ina well and to pump well fluid from thewell to the surface, said .main pump` including .Qonnected motor and pump. pistons and "being provided with 1an inlet port.; a .doublelactingfauxiliary pump of ,the reciprocating type axially aligned with `the. main pump. and inc'ludirjig''yav pump piston, said auxiliaryspum'p being provided with intake port means,y adaptedjto lconimunicate with the well .and discharge port.

means; means providing a. closed, pressureport substantially .equallto .that in. said ,discharge port means; and rod means 'directly/connecting' said pump piston of said auxiliary pump to one of said pistons of said main pump for operating said auxiliary pump so as to pump Well fluid from the well into said inlet port at a pressure higher than that in said intake port means.

3. In a fluid-operated pumping device, the combination of: a fluid-operated main pump of the reciprocating type adapted to be positioned in a well to pump well fluid from the well to the surface, said main pump including connected motor and pump pistons and being provided with an inlet port; a double-acting auxiliary pump of the reciprocating type axially aligned with said main pump and provided with a pump cylinder having a pump piston reciprocable therein, said auxiliary pump being provided with intake port means adapted to communicate with the well and communicating with the ends of said auxiliary pump cylinder, and being provided with discharge port means communicating with the ends of said auxiliary pump cylinder, said auxiliary pump having intake valve means controlling flow of fluid through said intake port means, and having discharge valve means controlling flow through said discharge port means; means providing a closed, pressure-maintaining passage communicating only with said inlet port and said discharge port means so as to maintain uid pressure in said inlet port substantially equal to that in said discharge port means; and rod. means directly connecting said auxiliary pump piston to one of said pistons of said main pump for operating said auxiliary pump so as to pump well fluid from the well into said inlet port at a pressure higher than that in said intake port means.

4. A fluid-operated pumping device as set forth in claim 2 wherein said auxiliary pump includes a balance chamber and wherein said rod means is tubular and extends into said balance chamber.

5. In a duid-operated pumping device, the combination of: a iluid-operated main pump of the reciprocating type adapted to be positioned in a well to pump well fluid from the well to the surface, said main pump including connected motor and pump pistons and being provided with an inlet port; a double-acting auxiliary pump of the reciprocating type axially aligned with said main pump, said auxiliary pump including a pump cylinder having a pump piston reciprocable therein, said auxiliary pump being provided with intake port means adapted to communicate with the well and discharge port means; means providing a closed, pressure-maintaining passage communicating only with said inlet port and said discharge port means so as to maintain fluid pressure in said inlet port substantially equal to that in said discharge port means; rod means directly connecting said auxiliary pump piston to one of said pistons of said main pump for operating said auxiliary pump so as to pump Well iiuid from the well into said inlet port at a pressure higher than that in said intake port means; and pressure relief valve means carried by said auxiliary pump cylinder for by-passing fluid from said discharge port means to the well.

6. In combination with production and power tubings set in a well and a tubular receiver which is connected to one of said tubings and which is provided with a seat, a fluid-operated pumping device adapted to be inserted into said receiver and to seat on said seat, comprising: a fluid-operated main pump of the reciprocating type provided with connected motor and pump pistons and an inlet port; a double-acting auxiliary pump axially aligned with said main pump, said auxiliary pump including a pump cylinder having a pump piston reciprocable therein, and said auxiliary pump being provided with intake port means adapted to communicate with the Well and discharge port means; means providing a closed. pressure-maintaining passage communicating only with said inlet port and said discharge port means so as to maintain fluid pressure in said inlet port substantially equal to that in said discharge port means; and rod means directly connecting said auxiliary pump piston to one of said pistons of said main pump for operating said auxiliary pump so as to pump well fluid from the well into said inlet port at a pressure higher than that in said intake port.

7. A huid-operated pumping device as defined in claim 2 wherein said auxiliary pump is secured to said main pump so that said main and auxiliary pumps are installable in and removable from the well as a unit.

8. A Huid-operated pumping device as defined in claim 6 wherein said auxiliary pump is secured to said main pump so that said main and auxiliary pumps are insertable into and removable from said receiver as a unit.

9. A fluid-operated pumping device as defined in claim 6 including annular sealing means carried by said pumping device intermediate said main and auxiliary pumps and adapted to engage said receiver in fluid-tight relation therewith.

CLARENCE J. COBERLY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,022,781 Pigott Dec. 3, 1935 2,081,223 Coberly May 25, 1937 2,134,465 Lacy Oct. 25, 1938 2,255,305 Zehner Sept. 9, 1941 2,284,505 Zehner May 26, 1942 2,314,583 Kitsman Mar. 23, 1943

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