US2921531A - Pressure fluid-operated pump structure - Google Patents

Description

Jan. 19. 1960 J. R. BRENNAN TAL 2.921,531

PRESSURE FLUID-OPERATED PUMP STRUCTURE Filed March 13, 1958 5 Sheets-Sheet 1 JUL 19, 1950 .1. R. BRENNAN l-:rAL 2,921,531

' PRESSURE FLUID-oPERA'rl-:D PUMP STRUCTURE Filed llarch 15, 1958 5 Sheets-Sheet 2 n ww 5% il ZJ, @ZM w 2555,55.5.25::, 5.5:-: :E z 55.55555,,E :E .zii E E 52:5. :ii ii. 5:5522.512225: y

Jan. 19, 1960 J. R. BRENNAN Erm. 2.921.531

PRESSURE FLUID-Ummm PUMP STRUCTURE 5 Sheets-Sheet 3 Filed March 13, 1958 1 1111111111 11111 1 11 111 1 1111, .11 11111 1111 1111111111. 11111111 11111 111 111 1111111111 111111111. .111. 11.11 ill .1l-..1 lili IIIIIIIIIIIIYl-lhl-i Sdin INVENToRs JOHN PEA/NA/v 111111 .1111111111 111111111111111111111111, 11111 1111. .1111111111111111111111111111. I lilHIlL-inmfhur.

Jan. 19, 1960 J.R.BRENNANE1'AL 2,921,531

PRESSURE FLUID-OPERATED PUMP STRUCTURE 5 Sheets-'Sheet 4 Filed lMarch 13, 1958 INVN'ToR E .....nJmlz .1.1, ,U

JOHN R. BRENNAN l3yr/7215715? .n OUDOFF Rgl M W ATTORNEY JID' 19 1960 J. R. BRENNAN Erm. 2,921,531

PRESSURE FLUID-OPERATED PUMP STRUCTURE 5 Sheets-Sheet 5 Filed llarch 13, 1958 75.1.; i ln| R, |l Imi-IBI i/,

INVENTOR; JOHN l?. REN/VAN 15575,? 5. LUDF/f Zaad Arron/EY United States Patent O PRESSURE FLUID-OPERATED .PUMP STRUCTURE John R. Brennan, Long Beach, and Peter S. Bloudolf, Whittier, Calif., assignors, by mesne assignments, to The National Supply Company, Pittsburgh, Pa., a corporation of Ohio Application March 13, 1958, Serial No. 721,178

24 Claims. (Cl. 103-46) This invention relates to pressure fluid-operated pump structures, the same essentially dealing with hydraulic pumps for downwell use.

The present structure comprises a sub-surface production unit consisting, essentially, of a reciprocating type hydraulically operated engine and pump combination which uses as its source of power clean crude oil (or other uid) under high pressure substantially greater than the pressure of the production of the well in which used.

The primary object of the invention is to provide a combination structure of the character referred to that is balanced hydraulically so that like amounts of high pressure operating fluid are used on both the up and the down stroke of the structure.

,Another important object of the invention is to pr vide a hydraulically-balanced pump structure which does the same amount of useful work in lifting either spent power uid or production on both upstroke and downstroke.

Another object of the invention is to provide a pump structure that for agiven size of outer casing and production tubing in a well, has a high output capacity as compared to the outputs of conventional pumps.

A further object of the invention is to provide a pump structure of the type above mentioned that, with minimum change, is adapted to a variety of different types of installations, as, for instance, installation on the end of a string of power oil tubing, both of the insert and casing type, and installation as a free pump, both of the parallel string and casing type. Thus, the present invention has for a further object to provide a pump structure adapted for such a variety of installations that the same comprises a versatile piece of equipment capable of all of the mentioned types of uses with a minimum of external changes.

A still further object of the invention is to provide a device of the character indicated that, in addition to the above-mentioned string-carried and free pump installations, is adapted to closed power oil systems. Thus, by providing an additional string of tubing, the power uid may be returned to the surface separately from the production fluid, rather than intermixed therewith.

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes, preferred embodiments of the present invention, which are given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. l, in seven sections, some of which are broken,

"ice

is a longitudinal quarter-sectional view of a pressure fluid-operated pump structure embodying a free pump installation according to the present invention.

Fig. 2 is a semi-schematic longitudinal sectional view of the pump structure shown in Fig. 1, with the reversing valve thereof in another position than the position of Fig. 1.

Fig. 3 is a similar view of said pump structure with the reversing valve in the position shown in Fig. l, the structure being modified to show a power-increasing size ratio between the engine and the pump of said structure.

Fig. 4 is a similar sectional view of another modification, the same comprising a parallel string type of free pump installation.

Fig. 5 is a semi-schematic longitudinal sectional view, partly in elevation, of a parallel string type of free pump, modified to show a size ratio between the engine and the pump of the structure.

Fig. 6 is an enlarged longitudinal sectional view of the pump structure, as shown in Fig. 4, the same clarifying details of the construction and their arrangement, and shown at the start of upper reversal of the valve thereof.

Fig. 7 is a further enlarged quarter-sectional view of the engine component of the structure at the start of upper reversal. v

Fig. 8 is a similar view of said engine component at the mid-point of the upper reversal.

Fig. 9 is a longitudinal quarter-sectional view showing the engine at the end of the upper reversal and the start of the downstroke of the engine.

Fig. 10 is a similar view showing the engine during its downstroke. 4

Fig. 11 is another similar view showing the engine at the start of the lower reversal.

Fig. 12 is yet another similar view showing the engine at the time the lower reversal is completed and at the beginning of the upstroke.

Fig. 13, in schematic fashion, shows a typical insert type installation of the present pump structure, the view showing a conventional system for supplying pressure fluid to the structure through a string of power oil tubing.

Fig. 14 is a schematic longitudinal sectional view of a pump structure, showing a casing type installation that may be used in connection with the system illustrated in Fig. 13.

Fig. l5, schematically, shows a pump structure in a free pump installation of the parallel string or tubing type.

Fig. 16, similarly, shows a pump structure in a free pump installation of the casing type.

The present fluid-operated pump structure comprises, generally, an outer jacket 26 that, in the case of a conventional installation, is connected to a string of power oil tubing 93 and, in the case of a free pump installation, to a swab nose assembly 25, said jacket 26 carrying such tubing or assembly at its upper end, a power subassembly 27 within said tubing 26, a pack-off 28 below the lower end of the power piston 27, a polished rod 29 extending downwardly through the pack-*off from the power piston, an outer jacket extension 30 around said polished rod, a lower pack-olf sub-assembly 31 extending downwardly from the jacket extension 30, a second outer jacket extension 32 extending from the lower packoff 31, a pump barrel 33 within the jacket vextension 32, a pump plunger sub-assembly 34 connected to the lower end of the polished rod 29 and operating in the barrel 33, and a bottom pump valve sub-assembly 35.

In a general manner, the upper end of the above structure, except for the swab nose 25, constitutes the engine section of the structure. More particularly, the power sub-assembly 2'7 constitutes said engine section.

For ease of reference, the following description will deal with two principal models which will be called the universal and the oversize. The universal model is best suited to most well'conditions `and is readily adaptable to either conventionaly or free pump installations and may be provided in either standard or ratio type forms. The standard model requires one barrel of power oil to 'displace one barrel of production, while the ratio form requires more than one barrel of power oil to displace one barrel of production. However, the latter operates at a lower power-oilpressure. v

The universal standard model is shown in Figs. 1 and 2.

The engine section V27 comprises, generally, the jacket 26, said jacket 26 enclosing a cylinder 37, a piston 38 reciprocative in said cylinder 37, a reversal spool valve 39 operative within the piston 38, the mentioned polished rod 29, and the high-pressure polishedrodpack-ol 28 previously mentioned.

vThe engine section 28 is disposed above a discharge section 40 that separates the engine section from the pump section therebelow. Said discharge section is enclosed in the outer jacket extension 30 and provides an annulus 41a into which spent power oil is exhausted from the interior of the polished rod 29 through ports 42. Ports 43 in the jacket 30 of said discharge section permit exhaust power oil to mingle with production uid in. an annulus 44 within a string of tubing 45 in which the present pump structure is disposed in a downwell position. Saidproduction is discharged from the pump section of the present structure, as will later be seen. The lower end of the discharge section 40 is provided with the low pressurepack-ot 31 previously mentioned.

The mentioned second outer jacket extension 32, the pump barrel'3'3, and the'plunger 34, constitute the pump section of the present structure. In the universal standard model, thebarrel 33Yhas the same bore as the engine cylinder 37. In the ratio'lform (see Fig. 3), the-bore of the barrelris usually smaller than that of the cylinder. However, there may be instances when smaller amounts of pressure oil are used, for making the barrel 33 `larger than the cylinder of the engine. This also constitutes a ratio form.

Actually,`the bottom sub-assemblyv 35 constitutes'the valvin'g for the pump section, the same including a flood check valve 46 that is carried by the plunger 34 Aand is spring-loaded to a closed position, opening only to pressure of ilow through a passage 46a in the plunger; an intake valve "46b; and ay discharge valve 46c. A .suitable uid passage 46d is provided between thejacket yextension 32 and 'the cylinder or barrel 33 and the valve assembly toinsure that suction pressure is effective at all times between the polished rod 29 and the portion of the barrel33 that is above the plunger.

In the drawing, the following conventionsare used to indicate the different uid pressure in the structure, while operating; stippling is used to indicate high pressurethe pressure of the power oil-the same being several thousand pounds per square inch, in practice, six thousand pounds being exemplary; crosses show low or production pressure which is considerably lower than the pressure of the power oil-'in practice, labout half Vof said pressure-the same varying according to different well depths and type of production uid; and crescents show suction as created when raising the production uid. Pressure drops where they occur, are indicated by combining the above conventions or symbols of the different pressures. The foregoing-are, of course, variable. The discharge pressure is equal to the hydrostatic head of the discharge fluid (production) yfplus'any pressure drop in the line tothe surface. vThesuction pressure is governed, principally, by the submergence 'of the pump structure within the `Huid being produced. The power oil pressure should be somewhat more than twice the dilfer'ence `be tween'the discharge and suctionl pressures -to obtain pump operation.

Referring more particularly to Figs. 1, 4, and 6 to 12, the pump structure there illustrated has three methods of installation. Onethe free pump system-entails placing of the entire pump assembly into the string of tubing 45 which is provided with a tapered seating shoe 47 in its production end, with a pressure sealing means 48 at about where the tubing pack-off 28 is located, and with a parallel and smaller tubing string 49 connected to the tubing 45 between the shoe 47 and the sealing means 48, the latter extending to the well'suface as does tubing 45,

With the pump structure above in a downwell position, pressure fluid (shown by stipples) is introduced into the tubing 45. This pressure is contained by the pump 4packoff 48 (Figs. 4, 6, 9 and l0) and is theprime mover or motive force of the engine 27. 'The discharge of said engine and of the pump 34 are routed to the common annulus 44 wherein they are commingled and returned to the surface through thetubing string 49.

Operation of the universal standard model (Fig. l2)

It will be noted that because ports 50 areprovided in the lower end of the cylinder 37, the lower end of the piston 38 is, at all times, open to high pressure oil in an annulus 41. The valve spool '39, being shown in-its down position, the area above the piston 38 is-open to discharge pressure. Therefore, the oil pressure acting in annulus 41 causes the `piston-.to moverupwardly,.-displac Ving oilfrom the cylinder 37, abovethepiston, vthrough a passage 51'andfa connecting `chamber SZin said piston fandinto the through'passageSS-in the valve'spool. This displaced oil now enters theypassage-54 fin thepolished power oil but said oil is lling the annulus beneath the 1 piston.

yThe operation of the spool valve will be later described but, when said valve iscaused to move upwardly to a position comparable to that shownin Fig. 8, the discharge from chamber 37 is shut oifand high pressure oil now enterspassage 51 and thence into saidehamber above the piston. This pressure above thefpiston causes thesame to move in a downstroke since the eiective area on the top of the piston is atleast twice as great as the area on the bottom of the piston. Thus, there is a net downward force to cause a downstroke. During such downstroke, about half power of the oil entering chamber 37 will be oil which is displaced from the annulus 41. The balance will be supplied from the power oil system (Fig. 13). On the subsequent upstroke, power oil from the system will replace the oil in annulus-41. Therefore, the amount of power oil required is thesame for both the upstroke and the downstroke.

The operation of the pump section 34 during the abovedescribed engine cycle of operation is as follows: on the upstroke of thepiston, iluid is drawn into ythe pump chamber 55 through'the intake valve 46b. Half of this fluid comes into the pump past the supplemental valve 56 and half is displaced around tl'iepump barrel33 from the yannulus 46e above the pump plunger 34. On the downstroke, intake valve V46h closes and discharge valve 46c opens, permitting fluid `in chamber 55 to be displaced into the discharge annulus v44 wherel it commingles with exhaust power oil to bepumped to the surface. While Fig. 3 shows a ratio form of pump, the same also shows a typical downstroke'pressure relationship.

During said downstroke, liuid is drawn from ysuction into annular chamber 46e. It canbe seen, therefore, that suction `uid is 'entering the pump past the valve 56 on both upstroke and downstroke. Hence, valve 56 is not essential to the operationbutprovision thereof will prevent a greatly accelerated cycle rate in the event of malfunction of valve 46h.

By providing a port 57 in the polished rod 29 so as to communicate a passage 58 in said rod with the annulus 46e, thereby connecting said annulus and chamber 55, a flood valving arrangement is provided. When laid port 57 moves past the pack-off 31 at the top of the stroke, exhaust power oil, at discharge pressure, is admitted to the inside passage 58. This causes the check valve 46 in said passage to open and to admit the exhaust power oil into chamber 55, filling any portion of the pump that may be left unfilled due to the presence of gas or cavitation during the suction stroke. Thus, the plunger starts its downward stroke in a barrel that is completely filled with uid. Also, this flood valving means minimizes the dangers of hydraulic shock, aids valve action, and improves eciency by initially compressing (or dissolving) occluded gases to cause a more complete purging of the pump during the downstroke.

The valve 39 comprises the reversal valve and the same is located and slidably operable in the piston 38. The complete piston and valve assembly, as shown in Fig. l, comprises the piston 38, the upper valve sleeve retainer 60, the upper valve sleeve 71, the lower valve sleeve 61, the piston to polished rod adapter 62, and ythe polished rod 29. The piston 38 is tubular in form land internally threaded at both ends, the upper end con- .necting with the retainer 60 and the lower end to the 'adapter 62. The upper outer cylindrical surface 63 of -the piston is preferably coated with a hard facing ma- -tet'ial and accurately ground to insure a close t with #the cylinder 37. The bore 64 of said piston is also :accurately finished to provide precise alignment between @the upper and lower sleeves 60 and 61 and a close t "with the lands 65, 66 and 67 on the valve spool 39.

The bore of the piston 38, at 68, above the bore 64 41nd,*at 69, below bore 64, is of slightly larger diameter .and the upper end 70 of the sleeve 71 and the lower end 72 of 'the sleeve 61 are preferably slightly enlarged to prevent their entering the finished bore 64.

Actually, the sleeves 71 and 61 are held in position "by hydraulic pressure, since the difference in areas between the two O-ring seals 73 and 74 provides a force 4upward at all times on the sleeve 71 and downward on sleeve 61.

The enlarged portions 68 and 69 do not affect normal operation but the same aid assembly, prevent the sleeves from moving out of position during transportation or during pump-out of a free pump from a well under reversed pressure and, in general, eliminate the distor- `tion that results from use of clamps to retain the sleeves rather than retaining them in position hydraulically.

The cylindrical seal surfaces 65, 66 and 67 are the largest diameter lands of the spool 39 and make up the control collar of the spool. The spool is also provided with cylindrical seal surfaces 75, 76 and 77. 0f these lands, land 76 is the largest, land 77 the smallest, and

lland 75 of a size between the other two.

Operation of the reversing valve If there is no pressure difference across the seal area that includes lands 65, 66 and 67, then the position of the spool 39 depends on the pressure in the annular chamber 78. When this 'pressure is low (see Figs. 10, 1l and 12), the spool is in its low position since the high pressure is acting downward on the difference between the diameter of land 75 and the diameter of land 76. When this pressure in annular chamber 78 is high (see Figs. 7, 8 and 9), the spool will be in its raised position since the high pressure is acting upwardly on the difference between the diameter of land 77 and the larger land 75.

In the lowermost position of the spool 39 (Fig. 12),

` the land 75 shuts olf flow of high pressure through the valve but opens the area above the piston to low pressure 'piston to make an upstroke.

charged from cylinder 37, above the piston, through passages 51 and chamber 52 and passage 53 in the spool. Hence, from the position of Fig. 12, the piston 38 makes an upstroke under the force of the high pressure in annulus 41.

At the top of the piston stroke, when the ports 42 in the polished rod 29 emerge above the top of the Packoff y28, the high pressure in annulus 41 enters ports 42 and moves through an internal passage into annulus 78, causing the spool 39 to shift upwardly. This movement occurs because the land.77 has a smaller area than the land 75. Therefore, while both lands are subject to high pressure, the differential will cause the mentioned upward shift.

When the spool is in its up position, the land 75 becomes interposed between port 79 and chamber 52 and opens said ports 79 to the high pressure that enters annulus 91 from chamber or annulus 41. After a few inches of downstroke from the position of Fig. 9 to that of Fig. 10, the port 42 emerges from the pack-off 28 into the low pressure on the down side of said packoff. As a consequence, the pressure in annulus 78 drops from high to low. At this point, the high pressure acting on the intermediate land 76 (larger than the land 75) starts movement of the valve spool 39 downward. However, as soon as land 65 starts to cover port 82 (Fig. l0), there is established a pressure drop in the fluid entering through said port 82. This reduced pressure is effective on the rather large areal difference between lands 66 and 75. The pressure below the land 66 in annulus 81 remains at full high pressure, acting upwardly on the areal difference between the lands 66 and 76. Since the difference in area between said lands is many times (about one hundred) the difference in the areas of lands 75 and 76, a relatively small pressure drop is required during the downstroke to balance out the downward forces on the spool to keep the same in an up position. Thus, the spool during the downstroke will automatically assume the correct position to maintain whatever pressure drop is required to keep said spool from shifting downward. Thus, with the engine operating at high speed, the valve will stay in an up position with respect to the piston, as in Fig. 10, even after the chamber 78 has reverted to low pressure. When the engine is operating slowly, the land 65 will move down to cover all but a small opening in port 82.

It will be realized from the foregoing that the stability of the valve, on its downstroke, is a dynamic one and, if for any reason motion is stopped during this cycle, the pressure difference across land 66 will not be maintained and the valve spool will shift down, causing the The above describes the upper reversal of the valve 39.

Lower reversal of said valve begins when the port 83 moves into the relief chamber 84, as in Fig. 1l. Since it is now no longer possible to maintain the reduced pressure above land 66, the valve will move down, since pressure fluid can now circulate freely around the annular passage that is formed by said relief chamber 84. The ow is through port 83, bypassing port 82 and any restriction thereof created by the land 65. Hence, the downward force of the high pressure on the difference in area between lands 75 and 76 becomes the predominant force and the valve 29 will shift down, again permitting the piston to make an upstroke.

In summation of the foregoing, Figs. 6 and 7 show the piston 38 at the top of its stroke with the valve 39 at the beginning of its upper reversal. As the high pressure moves the valve up to the mid-point of the upper reversal in Fig. 8, the low pressure in cylinder 37 is opened to the high pressure and the upper reversal of the valve is completed (Fig. 9). Now, there will be high pressure on the top of piston 38 and the same will start its downstroke from the position of Fig. 9 through the downstroke position of'Fig. vl0 ltothe position'of Fig. l1, Where the lower reversal of valve spool 39 starts. Since thespool movesjd'own, the low pressurein passage 53 yis opened 'to `cylinder 37 kwhen the vreversal is completed, as in Fig. 12. Hence, the piston 38 will start its upstroke which continues until the upper reversal is again instituted.

Since in hydraulic systems *it is desirable to avoid hydraulic hammer or shock, the present apparatus provides for means obviating a too lrapid build-up of pressure in any chamber. For'instance, at the top reversal position of the engine, lthe 4valve changesthe pressure above the piston 38 A'fromlow to high. It will be seen that, if any portion of the ports 79 remains open to exhaust after the spool vstarts-up, there `will be some upward movement lof 'the piston. When the spool starts its upward shift, "the `land 75 rst covers thelargest of the ports`79, leaving Jopen the smaller ports above for a brief instant to cause dissipation of any hydraulic shock that would be generated lupon complete closing of all these ports at the same time. In the present case, as the spool continues to shift upwardly, the land 75 covers the upper smallertport, causing a complete stoppage-of upward movement of thepiston. Then, saidland uncovers 'the lower smalleror metering port. At this point, land 67 closes port 85 and the upward movement of the spool isslowed since iluid in annulus -'81 can be replenished only through av small metering port 86. This almost instantaneous delay permits pressure equalization at ya rate that will obviate 'generation of hydraulic hammer above the piston 38.

Now, as the spool 39 moves upwardly, so that land'75 uncovers the largest of the ports 79, land 67 uncovers port 85 so that iluid 'freely `enters annulus 81 and the valve completes its top reversal without suppression.

The ratio pumps shown in Figs. 3 and 5fshow how, by reducing theiplunger 34 in size as well as thebarrel in which the plunger ts, an appreciable reduction in operating pressure will be required. To effect pressure "balances,y the polished 'rod 29 is also reduced where connected to the plunger 34. The pack oi 31 is proportionally reduced, also.

As can be seenfrom y'Fig..l3, a power unit 90, connected with a system lof separation, settling and storage tanks 91 and a valving system 92, may be used to provide power lluid, underisuitablyhigh pressure, to the present pump to operate the same. Fig. 13 shows the pressure luid as supplied throughA a string of tubing 93 in an insert type of conventional installation in which is shown the usual outer casing 94'and. production tubing 95. The present pump is axially disposed within the tubing 95. Fig. 14 shows acasing installation'that omits the tubing 95 since the casing carries the production. The free pump installations -of Figs. l and 16 respectively use parallel production tubing 96 `and the outer casing 94 to carry the production. These forms, in lieu of pressure tubing to Valign the pump, use the mentioned swab nose assemblies, detailed in Fig. v1,and which do not form a material part of the present invention.

While the foregoing specification illustrates and describes whatwe'nowcontemplate to be the best modes of `carrying out our invention, the constructions are, of course, subject to modification without departing from the spirit and scope of our invention. Therefore, we do not desire to restrict the invention-to the particular forms of constructionv illustrated and described, but desire to cover all modifcations'that may fall within the scope of the appended claims.

Having thus described our invention, what We claim and desire to secure by. Letters Patent is:

l. In a pressure-iluid-operated pump .structure for downwell use having ya pump including a reciprocating plunger and valve-controlled passages to displace well fluid upwardly toward .the surface and pressure-fluidconducting means for tluid under pressure substantially greater `than the pressure of-the wall Huid and having a cylinder with its lower end open to receive the 'pressure lluid rand a piston in said cylinder connected to #said plunger and movable upwardly under force of said prossure duid, the improvement comprising a valvefmember travelling with and mounted to slide relative Vto the piston, said valve member having a through axial passage and provided with differential Varea annular faces subject -to the -rforce of -the'mentioned pressure fluid to slide-the valve memberarelative to the piston, a tubular member mounted to lmove with the piston and within which a portion `of the valve-member resides, said portion being provided with a land and said( tubular member fhaving vport means controlled by said land during'the mentioned relative-.sliding movement of the valve member, said'polt means being in communication with the upper end of the cylinder, said land, in one position thereof relative to the port means, openingthe latter to exhaust uidfrom the lupper end of the cylinder through the Amentioned passage in the valve member, and, in -anothervposition relative'to the port means opening the latter to conduct pressure 'uid,vabove-mentioned, to said upper end'of the cylinder.

2. In a pressure-uid-operated pump structure accordingfto claim 1 in which the connection between theemen- :tioned plunger'and piston has a longitudinal passagelantl Vthe axial ypassage in said valve member and said latter passage are in exhaust communication, the further improvement thatdisposesthe piston in such operative rela- =tion to the valve-controlled passages that the latter passages conduct exhaust pressure fluid from the cylinder above the vpiston to provide lower pressure above Ithe piston .than is the `pressure of the fluid upwardly onlibe piston.

V3. Iny a-pressure-'fluid-operated pumpfstructure accord- 'ingto claim y2, the further improvements that comprise .and the space within the piston inwhich the valvefmem- `ber slides to, thereby, control the rate of sliding .movement of the valve member relative to the piston.

4. In a pressure-fiuid-operated pump structure 'for downwell use having a pump including a reciprocating plunger and valve-controlled passages to displace well fluid upwardly toward-the surface and pressure-fluid-conducting means for fluid under pressure substantially greater than the pressure of the well iluid and having a cylinder with its lower end open to receive the pressure iluid and a piston in said cylinder connected to said plunger and movable upwardly under force ofsaidprcssure fluid, said connection between the plunger and piston comprising apolished rod, there being a pack-olf around the rod located between said plunger and piston, the improvement that comprises a hollow valve member travelling with and mounted to slide relative to the piston, said valve member being provided with differential area annular faces subject to the force of the mentioned pressure fluid to slide'the valve member relative `to the piston to control llow of the pressure-tluid-conducting means, a tubular member mounted to move with the piston and within which a portion of the valve member resides, said portion being provided with a land and said tubular member having port means controlled by said land during the mentioned relative sliding movement of the valve member, said port means vbeing in communication with the upper end of the cylinder, said land,-in one position thereof relative to the port means, opening-the latter to exhaust'uid from the upper end of the cylinder through the mentionedV passage in the valve member, and, in another position relative to the'port means opening the latter to conductjpressure tluid, abovementioned, t"o said upper end of the cylinder.

'5. In a prcssureuidoperated pump structure' `for downwell use having a pump including a reciprocating plunger and valve-controlled passages to displace well Huid upwardly toward the surface and pressure-lluid-conducting means for uid under pressure substantially greater than the pressure of the well lluid and having a cylinder with its lower end open to receive the pressure uid and a hollow piston in said cylinder connected to said plunger and movable upwardly under force of said pressure lluid, the improvement comprising a valve member travelling with and mounted to slide relative to the piston, said valve member having a through axial passage and provided wit-h differential area annular faces subject to the force of the mentioned pressure lluid to slide the valve member relative to the piston, said piston being provided with a tubular part interiorly thereof and axed thereto and within which a portion of the val've member resides, said valve portion being provided with a land and said tubular part having port means controlled by said land during `the mentioned relative slid- -ing movement of the valve member, said port means being in communication with the upper end of the cylinder, said land, in one position thereof relative to the port means, opening the latter to exhaust iluid from the upper end of the cylinder throughl the mentioned passage in the valve member, and, in another position relative to the port means opening the latter to conduct pressure fluid, above mentioned, to said upper end of the cylinder.

6. In a pressure fluid-operated pump according to claim in which the pack-off comprises longitudinally spaced pack-oil sleeves defining a space therebetween and the mentioned rod is provided with ports and passages that conduct spent pressure uid from said cylinder to the space between the pack-off sleeves, and an additional passage in the connection communicating the.

cylinder below the piston with areas within the piston and open to said annular faces of the sliding valve member.

7. An engine for a well pump, said engine comprising a cylinder closed at the top and open at the bottom to ingress of high pressure liquid having a pressure substantially greater than the Apressure of the fluid displaced from the well, a piston reciprocatively mounted in said cylinder and provided with an axial bore having diierent sized bore diameters along its length a low pressure discharge passage below the cylinder, a set of ports communicating the bore of the piston and the annular areas around the piston and inward of the cylinder, and a sliding valve member having a through axial bore in communication with said low pressure discharge passage, said valve member being provided with lands to slidingly t the respective dierent bore diameters to, thereby, control ow through the different ports in a first position permitting lluid to exhaust from the upper end of the cylinder through said axial bore and in a second position admitting high pressure lluid from the annular area below the piston to the upper end of the cylinder.

8. An engine according to claim 7 in which the diierent sized lands dene different sized annular end faces subject to the force of the high pressure liquid.

9. An engine for a well pump according to claim 8 in which the pressure in the closed end of the cylinder changes between high and low according to the control by portions of the valve member of flow through the ports under different positions of the valve member relative to the piston.

10. An engine according to claim 7 in which the valve member is formed as a cylindrical spool in which is provided an intermediate set of lands that control ports only, and an upper and two lower lands that deline the mentioned annular end faces.

l1. In an engine for well pumps and having a reciprocative piston provided with an axial bore, a set of ports communicating said bore and the outside of the piston, an axially hollow sliding valve member reciprocatively lt') disposed in the piston bore, cooperating bore sections 6d the piston and lands of the valve member guiding the latter in movement axially of the piston, and a set of longitudinally spaced lands of differential areal size on the valve member in position to control said set of ports' during the mentioned relative axial movement.

12. In an engine according to claim 1l, the longitudinally spaced lands being disposed between the upper of the first-mentioned lands and two other such lands.

13. In an engine according to claim 1l, the longitudinally spaced lands being disposed between the upper of the irst-mentioned lands and two other such lands, said upper land being intermediate in size between the twolower lands, and the upper of the lower lands being largest of the three.

14. A reciprocating fluid-operated pump structure comprising a pump, an engine above the pump to operate the same, an elongated connection between the pump and the engine, a pack-off through which the connection extends, and a tlood valve means controlled by the connection and movable by the engine between positions above and below the pack-oil, the llood valve means being arranged relative to the pack-off means to cause fluid communication around the pack-off means between the engine and pump when the latter approaches the top of its stroke.

l5. A reciprocating Huid-operated pump structure according to claim 14 in which the elongated connection comprises a polished rod and the pack-off comprises a sleeve having a sliding sealing engagement with said rod, and said llood valve means comprises a port and a cornmunicating longitudinal passage in the rod and opening into the pump.

16. A reciprocating Huid-operated pump structure according to claim 14 in which the elongated connection comprises a polished rod and the pack-off comprises a sleeve having a sliding sealing engagement with said rod, and said llood valve means comprising a port and a communicating longitudinal passage in the rod and opening in the pump, the port opening into the .engine when the latter approaches the top of its stroke.

17. A reciprocating fluid-operated pump structure comprising, in combination, a pump having a plunger, an engine above the plunger and having a piston, said engine being operated by pressure iluid that becomes spent after such operation, an elongated connection between the plunger and the piston whereby the same reciprocate. together, the pump being subject to suction pressure of at well in which placed, two longitudinally spaced pack-offs between the pump and the engine and through which the connection extends, said pack-offs defining a chamber therebetween, said chamber being receptive of spent iluid from the engine, and a discharge from the pump independent of the mentioned chamber, the lupper pack-off separating the mentioned engine-operating pressure iluid from spent pressure in said chamber and the lower` packofi separating said spent pressure from the mentioned suction pressure of the well.

18. A pump structure according to claim 17 in which a ood valve means controlled by the connection is provided and the same is movable with the connection into and out of communication with the chamber.

19. An engine according to claim 7 in which two lands are provided one above the other and the upper land being larger than the lower land, the bore in which the upper land is slidingly fitted being provided with ports controlled by the latter land to reverse the ow of lluid through said ports and opening the area above the piston to high pressure and low pressure alternately during strokes of the piston.

20. In an engine for well pumps, a hollow piston, a pair of longitudinally spaced sleeves, a hydraulic seal between each said sleeve and the interior wall of the piston hollow, an abutment on the end of each sleeve, said abutments being opposite and locating said sleeves in the.

mesma-1 pistonfagainst pressure in the spacebetwe'en 'the sleeves and :effective to bias lthem in avdirection toward Vtheir respectivelabutments, and ja valve spool slidingly 4guided by said sleeve.

-2l-. In a prefssure-uid-'operated vpump structure for downwell use having -aV pump including a `reciprocating plungerv and valve-controlled passages/:to displacewell uidupwardlygtoward the surfaceand pressure`uid-con ducting means for fluid under pressure substantially greater than the pressure of `the well uid and having a cylinder with its lower-end open to receive the pressure fluid-and a hollow 'piston in said cylinder connected to said iplunger and movable upwardly lunder force` of said pressureruid, the improvement-that comprises a `sleeve within the hollow of the piston, a memberl xedlyconnesting `said sleeve and 4"theupper end of the piston and defining an annular chamber, said chamber being in communication with Vthe cylinder 'above the piston, said sleeve having port means connecting said chamber and the fsleeve interior, a valve member travelling withand mounted to slide in `the hollow of and relative to `the piston and having a through axial passage and provided with differential area annular faces `subject to the force of the mentionedpressure fluid-to slide the valvemember relative to the piston, the upper end of the valve member being slidingly engaged in said sleeve, said end being provided with a landrto control low in said port means during the mentionedrela't'ive sliding movement offthe valve member, said land, in one 'position thereof relative to the port means, opening the llatter to Aexhaust uid from the upper end of the cylinder through the mentioned passage in thevalvemember, and, in another position relative to the port means opening .the latter to conduct pressure fluid, above mentioned, to said upper end of the cylinder.' i

22. In a pressure-iluid-operated pump according to claim 2l, the mentioned sleeve being provided with a downwardly-facing end, asecond sleeve lxedly connected to .the lower portion of the piston and directedto'have anupwardly-facing end in spaced 'opposition tothe ymentioned end of the first sleeve, the portion of the valve that slides in the hollow of the piston beinggmovable between said sleeve ends and in limiting abutmentengagement with said ends according to the mentioned 'two positions of ythe mentioned port-controlling'land.

23; Ina pressure-Vuid-operated pump structureA for downwell use having a; pump including a reciprocating plunger and valve-controlled passages to displace well uidupwa'rdly toward the surface and pressure-ud-conducting means for `luid under pressure substantially greater than the pressureVV ofthe well uid and havli'ngfa cylinderwith its lowerend open to receive the pressure uid and a piston in said cylinder connected to said plunger and movable upwardly under force of saidpres` sure Huid, -saidf connection between the plunger and the piston Acomprising a polished rod, there being a pack-o5 around the-rod located between said plunger and piston and Va set of Huid-passing ports in said piston, the iin,- provement that comprises asleeve within the hollow lof the piston, a member Xedly connecting said sleevev and the upper end ofthe pistonand defining an annular chainber, saidffchamber beingin communication with the cyl# inder above the piston, said sleeve having port means connecting saidechamber and the sleeve interior, a valve member travelling with and mounted to slide in theholflow of and relative to vthe piston and having a through axial passage and provided with differential area annular faces `subject to the-'forceof the mentioned pressure fluid to slide-the valve member relative-to the piston, the upper end of the valve member being slidingly engaged-in `said sleeve, said end ybeing provided with a land to control flow in said port means during the mentioned relative sliding-movement 'of the valve member, said'land, in one position thereof relative to the port means, opening the latter to exhaust lluidffiom the upper end of thecylinder through the mentioned passage in the valve member, and, in another position relative to the port means opening the latter to conduct pressure fluid, above mentioned, to said'upper end fof the'cylinder.

24. In a vpressure-iluid-operated pump according'to claim 23, the mentioned 'sleeve being provided with'fa downwardly-facing end,l a'second sleeve fixedly connected to the lower portion of the piston and directedto have an upwardly-facing end in spaced opposition to the mentioned 'end 'of the first` sleeve, the portion of `the valve that slides inthe hollow of` the piston being movable between said sleeve ends and in limiting abutment 'engagemen't with said ends according to the mentioned two positions of the mentioned Vport-controlling land.

References-Cited in the le of this patent UNITED STATES PATENTS 2,276,783 Kennedy etal. i Mar. 17, 1942 A2,473,864 Coberly' June 2l, V19219 2,497,348 Ecker at Feb. 14, 1950 2,631,572 Dempsey Mar. 17, 1953

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