US2596146A - Well pumping system - Google Patents

Description

May 13, 1952 M. w. HAlNr-:s

WELL PUMPING SYSTEM 3 Sheets-Sheet l Filed March 17, 1945 May 13, 1952 M. w. HAINEs WELL PUMPING SYSTEM 3 Sheets-Sheet 2 Filed March 17, 1945 k\\\\ \\\\\\\NWN May 13, 1952 M. w. HAINES WELL PUMPING SYSTEM 3 Sheets-Sheet 3 Filed March 17, 1945 I!" lxl lllllllllllllllll Il, I I l I I I l Il lllll 3 J i fw, Z \,1\. T l WV//lwdvhnlunnwnwe Y i 2 J LA .1 n m a a a \ow\ z2 lll u z I m w M. /l M. M 3 N1 NI. -..u Iliff-' -z |||V| .ll ,i\\lq\\l\\h!mr-.l`fhd JU M 5. u 1I 3 Patented May 13, 1952 WELL PUMPING SYSTEM Marcus W. Haines, Long Beach, Calif., assignor to Vernon Tool Co. Ltd., Alhambra, Calif., a corporation of California Application March 17, 1945, Serial No. 583,355

4 Claims.

This invention has reference to the pumping of deep wells by rod operated pumps. The general object, and other further particular objects, and corresponding accomplishments, will appear from the following preliminary observations and, in greater particular, from the then following detailed descriptions of preferred forms of apparatus for my pumping system.

When oil is being pumped from a deep well by a rod actuated pump, and particularly when the oil is heavy and viscous, the pump rods sometimes sink in the oil so slowly that the rate of pumping is very much restricted. In the ordinarily used pumping system the rods are located inside the tubing through which the oil is being pumped to the surface, with the rods in direct contact with the pumping column. Attempts have been made to somewhat overcome the diiiiculty by applying force `to the upper end of the rods to force them down; but no great amount of downward force can be applied to the long slender rod without buckling the rod; so that this attempted solution does not eiectually eure the diiculty.

To completely overcome the difficulty, I provide in my system that the pumping rod shall be kept entirely out of contact with the pumping column, by utilizing a tube which immediately surrounds the rod, with the pumping column outside that tube. Then, a iiuid of low relative viscosity may be maintained in the rod-surrounding tube, either merely for the purpose of preventing entry of the Well iiuid to the tube, or for the purpose of lubricating the rod, or for both of those purposes. Broadly speaking, the fluid may be either gaseous or liquid, heated or cold, and the body of such iiuid may be maintained statically in the tube around the rod or it may be constantly forced into the upper end of the tube at such pressure and in such quantity as to continuously force some of the lubricating iiuid out into the pumping column, with various beneficial results. In this description I will speak ofthe rodsurrounding uid as the lubricating" iiuid to verbally distinguish it from the well iiuid, although in some cases (e. g. where the iiuid is a gas) it does not in itself have any positive lubricating quality; but it can be said to have a relative lubricating quality compared with the heavy and viscous well iiuid. Generally speaking, the rod-surrounding uid may be more accurately deiined as a iiuid of relatively low viscosity.

The lubricating fluid will, in general, be more fluid, or lighter and considerably less viscous than the well iiuid, and its admixture with the well fluid tends to lighten the pumping column and render it less viscous and therefore easier to pump. If a gaseous iiuid is used, its admixture with the well iiuid forms a pumping column which is lightened and acts, pro tanto, like a gas lift. And furthermore, if the fluid is pumped down the tube in heated condition, it tends to iiuidize the pumping column by raising its temperature.

The apparatus for my system may take various forms. For instance, a relatively small tube may directly and fairly closely surround the pump rods, inside the ordinary tubing; and the pumping column may then be pumped upwardly in the tubing outside the lubricating tube. On the other hand the usual tubing, or a pipe which takes its place, may be used as the lubricating tube, and the pumping column may then be pumped up to the top between the tubing and the well pipe. Such variations of the apparatus, as well as other variations of apparatus and functions are set out in typical and preferred forms in the following detailed description, referring to the accompanying drawings in which,

Fig. 1 is a longitudinal section, with parts in elevation, showing my pumping system as it may be applied to a well, utilizing the special inner lubricating tube;

Fig. 2 is a lower continuation of the parts shown in Fig. 1;

Fig. 3 is an enlarged longitudinal section of certain portions of the apparatus shown :in Fig. 1;

Fig. 4 is a similar longitudinal section. showing a modified form of apparatus in which the well fluid is pumped up through the well pipe externally of the tubing;

Fig. 5 is a similar section showing further modiiications;

Fig. 5a is a diagram showing means for ccntrolling the application of pressure to the lubricating iiuid;

Fig. 6 is a similar section showing further modiflcations; Y

Figs. 7 and 8 are longitudinal sections showing the upper and lower parts of another modified form of apparatus.

It may be noted that, for clarity of illustration, the sectional views of Figs. 3 to 6 are somewhat distorted, as compared with the relative dimensions of my working designs, the length dimension of the parts as shown in those iigures being shown at a smaller scale than the transverse dimensions.

Referring first to Fig. 1, I0 designates a well pipe or well casing within which the ordinary tubing II is shown. The pump rods are shown at I2 entering the upper end of the well through stuffing box I3. For purposes of simplicity, none of the usual joints are shown for any of these parts, nor for the inner tube which directly surrounds the pump rod, and it will be understood that whenever I refer to a 'pump rod, I .mean to include that element whethersolid or hollow, and also to include cable which is sometimes used. The inner tube is shown at I4, surrounding the pump rods more or less closely, and the space I5 between tube I4 and tubing II is, in this design, the space through which the well fluid is pumped to the top. They upper end of tubing Ilis hung from a cap 2G which closes the upper end of the well pipe, and the upper end of inner tube I4 is hung from an upper part of cap 20, or from another cap 2| seated on cap 25. VThe upper cap 2| has a pipe connection opening 22 through which Vthe rod-'surrounding fluid is inltr'o'ducedfu'n'der suitable pressure; and the lower capY has pipe connection `openings 23,1communicating Vwith the space between tube I4 and -tubing II,.to carry away the pumped oil. Fluid under 'regulated pressure and in regulated quantity may be introduced at 22 through the line indicated"-diagrammatically at 22a from the pump indicated diagrammatically at 22h.

Reference is now had more particularly to Fig.

3-which is an enlarged section showing the vapparatus from a level'just below the lower .end

-ofthe pump rod proper down to the pump plunger and its working valve. The well casing is not shown in'rthis enlarged View. The lower endf [of pump [rod I2 is shown as connected with'a special tubular connector 25, .having perforations 26 yso that the iiuidv which is forced down tube I4 underA pressure, may enter the interior .of connector 25. VExtending downwardly from connector there is tubular rod 21 through which the'uid may pass on'downwardly to a valve controlled outlet 2S at the lower end of tubular rod 21 and preferably just above 'the upper end of pump Vplunger V29. As` typically illustrated here the outlets 28 are'iormed 'in a valve? cage 30 which is attached to the lower end'of tubular'rod 21, and pump plunger 29 is attached to the lower end of 'valve` cage 30 `by the connection sleeve 3l. The pump plunger may be of any suitable kind; it is here illustrated Vvlas `one'which has the cage 32 for working valve 33 atV the topV ofthe tubular portion 34` of the plunger..

lTubular rod 21 forms in effect a downward continuation of pump rod I2. At some suitable point above valve cage 30, and preferably close tothe valve cage, tubular rod 21 passes through a double packing unit which, in this form of the device, is stationarily mounted `in the inner tube I4. As shown in detail in Fig. 3 this packing unit is mounted in a special collar member 36 which is connected between the upper-portion I4 of the inner tube and a lowerl portion I4a which extends on downwardly from collar member 36. Seeing that collar member 3S is merely structural, and forms inA effect a part of tube I4, the collar is not shown in Fig. 1, tube I4 being there shown simply as extending con- -tinuously past packing 35. The lower portionv of Atube I4, 'specically the part Ilia, as shown in Fig. 3, has openings 31 throughits wall to form 'passages leading from the inside of' :the tube to the pumping column space between the tube 1- and tubing II. y This lowerlpa'rt 7I4aof-tube Illl Y is preferably locally enlarged as illustrated and inner tube I4is lowered into the well. 'l5

at its lower end it preferably carries the pump barrel 4). The pump barrel seats, as usual, at its lower end on a suitable seating 4I which is carried by tubing II. Pump barrel 45 carries the usual standing valve 4ta. For simplicity, in Fig. l pump barrel 40 is shown as if it were simply a downward continuation of the lowerpart of tube I4. Thereason for so mounting the pump barrel on the lower end of tube I4 is to make provision for lowering the pump barrel, the pump plunger, and the tubular rod 21 assembled in packing35, all together as one unit when the After those parts ia'relowered and the pump barrel seated, Vthen the pump rods may be lowered invside tube I4. vAI special rod joint is provided so that the lower end of thepump rod may then be effectively connected to Vthe lower tubular rod 21. As shown in Fig. l, a special connector vmember 5G is mounted on the lower endvfof-.the pump rod proper I2, equipped with aspecial thread 5I whichtakes a similar thread at.` the upper end of the short piece of pump rod [72a which is immediately `connected with tting 25.

kAssuming that the pump rods and pump plunger are being reciprocated vertically, the well fluid is taken in at the lower end of the pump barrel past valve 45a and is `pumped upwardly in the usualmanner by the plunger valve 33. -This upwardly -moving pumping column first .passes upwardly into the interior o f lower. tube I4a and thenoutthrough openings :i1-into' the pumping column space I5 between tube Hand tubing II, and thus to the top of the well. The

.pumping column may be preventedY from entering the inner tube I4 simply by the pressure which is maintained on the nuid in that tube. Assuming forinstance that-packing 35 is not used, so that the interior of lower tube I4a is directly open tothe upper portion I4 of that tube `(instead of being open to it through tubular rod 21 and `valve cage 30), then ifthe fluid in tube I4 is maintained under su'icient pressure, the pumping column cannot move upward through tube I4 but must move upwardly outside that-tube.Y And the samething is true. if packing 35 is used andthe fluid is maintained in tube I4 and in-tubular rodV 21, and if no valve-is used in valve cageil. Under any such condition, ii

a static body ofuid `is maintained in tubeV I4 undera pressure just equal to the. pressurefof the' pumping column at or'just above openings 31, theV pumping Ycolumn cannot lmove Vupwardly iiuid of the-pumping column.

The' same generaloperating conditions (pre- `venting the pumping columnrfrom movingupwardly through -tube I4) may ofv course beat- Atained'by'not providing a passage for the lubricating fluid ldownwardly through rod 21 past packing 35;or by providing whatamounts tothe same thing, an upwardly closing'valve' in valve In either such arrangement, the pumpingcolurnn is prevented from moving up through tube I4 by the fact that rod 21 passes :through packing `35 and is itself closedagainst upward nowof iluid. In any such arrangement leakage of the well fluid past `packing 35 is prevented by the statically maintained uid pressure abovethe pac-king. Aside from preventing that leakage Vit would notbe' necessary to maintainapressure on the fluid in tubeI 4.

-Of al1 such arrangements I prefer at present Iso-utilize one which provides a downwardly opening valve through which the lubricating iiuid may be forced out in lesser or greater amounts into the pumping column. So I preferably provide the downwardly opening valve 60, closed upwardly by spring El, in valve cage 30. In effect this valve prohibits upward passage of pumping column fluid from lower tube |4a into the upper tube portion |4. And thus, in functional eifect the valve 60 is the equivalent of a downwardly opening annular valve which would control the annular passage which packing 35 seals off, assuming that rod 21 were solid. -I prefer however to make the arrangement as shown in Fig. 3 because of the simplicity and reliability of the valvular means thereby provided. 1

One of the reasons for using an upwardlyclosing valve, such as that shown at 60, or one which will perform the same functions as-above outlined, and particularly for using a valve which is closed upwardly by some spring pressure, is to control the discharge of the lubricating fluid into the pumping column. Assuming for instance that spring BI puts an equivalent pressure of 25 lbs. per sq. in. on valve 60, then valve 60 will only open downwardly if the pressure on the lubricating iiuid is raised to a point equal to the pressure of the pumping column at the valve plus 25 lbs. per sq. in. or more. Thus, if it is not desired to discharge any of the lubricating fluid into `the pumping column, the lubricating fluid may be maintained at a pressure (at the valve) which is either equalto the pressure of the pumping column at that point, or in excess of that pressure by an amount less than 25 lbs. per sq. in. The spring pressure imposed on the valve thus provides for variations or inaccuracies of the lubrieating fluid pressure with relation to the pumping column pressure. the latter being of course subject to variation in the pumping operation.

On the other hand, if it is desired to discharge lubricating fluid into the pumping column in any quantity, large or small, the pressure on the lubricating fluid is raised tc a point suiiicient to open valve 60. If it is desired merely to maintain tube I4 full of lubricating iiuid, it may be desirable to raise the pressure to the point where a small amount of that fluid is constantly or intermittently discharged past valve 60, in order to be assured that tube I4 is lled with the uid.` Maintenance of a higher pressure on the lubricating iluid, and introduction of a commensurate volume of that fluid, will cause a discharge past valve y6|) of a correspondingly larger volume of that fluid into the pumping column.

As I have stated before, the lubricating fluid may be either gaseous or liquid. If it is gaseous, and introduced under sufficientA pressure and in sufficient quantity to discharge into the pumping column in any appreciable volume, it will act to lighten the pumping column as well as to fluidize it, and in fact it will, in proportion to the volume of introduction act like a gas lift on the pumping column.

On the other hand, a suitable lubricating liquid of relatively low Vviscosity will, if discharged in any appreciable quantity in the pumping column, tend to uidize the pumping column. Suitable lubricating liquid for the purpose may be for instance oils which are more fluid or lighter and less viscous than the well iiuid; or the lubricating liquid may be any suitable low viscosity liquid, preferably but not necessarily, miscible with the well fluid. and which has the funtcion of rendering the well uid more liquid and less viscous. Generally speaking, a liquid of lower viscosity than the Well fluid, and miscible with it, or forming a more fluid solution with it, is suitable.

With any kind of lubricating fluid.. pumped down the lubricating tube in any substantial quantity, heat may be carried to the pumping column to reduce its viscosity. For that purpose, a lubricating liquid is preferable to gas, having a greater heat carrying capacity than :a gas. If such a liquid is heated to a fairly high temperature and is pumped down and into lthe pumping column in fairly large quantity, the pumping column may be appreciably heated and reduced in viscosity throughout its length by rise in temperature alone. The heat may be transferred to the pumping column by conduction and radiation through and from the inner tube I4, and by conduction when the lubricating fluid finally discharges into the pumping column.

In the preceding discussions of operation of my system it has been assumed that the discharge of the lubricating fluid or gas into the pump column is close to the pump. The level at which that takes place is determined, in the apparatus form of Fig. 3, by the relative position of openings 31. That level may be at any suitable or desired distance above the pump.

Fig. 4 shows a modification which is, in general structure, similar to the structure shown in Figs. 1 and 3, but in which the well fluid is pumped out in the annular space immediately inside the well pipe IDI. In this arrangement the pumping column immediately surrounds the tube or tubing which carries the lubricating fluid; and that tube or tubing may be of any suitable size. For instance it may be the same pipe or the same size pipe which is ordinarily used as tubing in a-well, or it may be a pipe of special or smaller than tubing size. The lubricating tube |4| shown in Fig. 4 will communicate at its upper end to the fluid introduction opening 22 of Fig. 1. The rod (corresponding to rod |2a) is shown at |2|a, the tubular perforated connector is shown at 25| and the tubular rod extension at :21| passing through the packing 35|, all substantially similar to the corresponding parts in Fig. 3. The valve cage at the lower end of tubular rod 21| is shown at 30| with its upwardly seating ball valve 60| and discharge opening 28|. The lower end of tube |4|a carries a packer |30, illustrated here diagrammatically, of any suitable type to tightly and sealingly engage the inner Wall surface of well pipe I 0 I. The pump plunger is shown at 29|, carrying the plunger valve 33|, and connected to the lower end of valve cage 30| in the same manner as before described. The pump barrel 40| is in eiiect carried by the lower end of tube I4Ia, being shown here as carried by the packer unit |00 which is carried by that tube.

The operation of this form is substantially the same as that of Fig. 3 except that, from the practical standpoint, the pumping column is moved upwardly inside the pipe which is ordinarily the well pipe instead of ordinarily the tubing. The lubricating iluid is introduced into and maintained in, or is pumped down, the lubricating tube 4I in the same manner as before described, and out past valve 60| into the space between 30| and |4|a, and thus into the upwardly moving well iiuid which is moving out through openings 31|. In fact. the mode of operation of the form shown in Fig. 4 is exactly the same as that shown in Figs. l, 2 and 3, as tube |4| is functionally the same as tube I4, and well pipe |0| is functionally VV22ml and with an exhaust outlet line 22|e.

an 'illustrationvalve arm 22 lf will be in the position shown in full lines to connect line 22m with l"pressure line 22H1 during the-down stroke of the "rod The rods are shown, for instance, at the ""upperend of "the stroke. where a pin or lug 99 ij'hascontacted and raised theV lever 'arm 98, coni'cfedlbylinkSl to valve' arm22lf', to raise it to escenas tube I4 Vand wellpipe rml, or thesealingbetween pump barrel 40| and well.4 pipe =||,-isfaccom pli'shed by packing Hill.

'.The'structure ofFig; 5.'.is in the mainthe same 'as-'that shown in Fig. ,4, withnthe exception of the packing, so the other parts of Fig. 5 aredesignated with the same numerals as applied to Fig. 4.

f Instead of utilizing a the packing I which .is stationarilwset in tube -illlasin Fig; 4l, .thefdevice of Figutilizes a packingunit in the form-,of a Y piston 35m which'is fixed ontubularfrod 2li and moves through the pumping stroke .withthat rod. The result isi that the Apressure or" the lubricating -Yiiuid is Ymaintaineddownwardly on the piston-and thus exerts avfcrce tending to move-the pump plunger downwardly andtending to stretchthe rods. 'The-amount of that positive downward toreedepends-upon'the effective area ofpiston Silla and also on thepressure which is maintained on thelubricating fluid. That pressure Vmay be Vconsiderably higher than the well fluid lpressurepbeing controlled by the strength `of Aspring lill. VIDue to the presence of valve A66|, the effective area on which the downward pres- -sure` of the lubricating fluid isexerted, is equal tothe total areaof a circle whose diameterris the. diameter of .packing piston 35m minus the cross-sectional area of pump rod |2|a.

This downwardly exerted force may be utilized 'simply for-.keeping the rod in stretchedcondition -andto accelerate the downward movement of theA rods and pump; or it may be utilized to operate a double-acting pump on the downward :stroke- Double-acting pumps are well known and need no particular description here. In gen eral, they -arel pumps with special valvulararrangements in their plungers, so that theyV pump fluid upwardly .on the down stroke as well as the 'upl stroke. To pump on the down stroke the plunger of course must be forced down, and the downward pressure on packing 35m may be uti- .x

lized for that function. This form of .myapparatus also facilitates the use of a cable as the pump` rod.

`Also,l,in the arrangement of Fig. 5, the pressure on the lubricating fluid may either be maintained ,p

constantly or may be applied at the top of the Fig. 5aV shows 'diagrammatically how this may be accomplished.

In that ligure the .pump rod is represented at |2i and the upper end of tube Mi is shown as hang- "ing from the head 2H so'that opening 22| oommunicates with the tube. Fluid supply line 22 la connects the line 22m with pump pressure' line AS 'well only during the downward stroke, being re- .lieved 'during' the upward stroke.

theffull line position-atthe endoftheupstroke.

On the. down -stroke the vValve :remains in.v that position until, at thependrof the down stroke, the rod lug :9S contacts lever' .58v and moves itdown to'throwsthe valve to the dotted line position,

Fig.x6. .shows another variant *whichV Y.may be applied Ato Hany yof the forms hereinbeforedescribed; the modication havingto dosolelywith thelocation .ofl the -valve vwhich relieves.. the lubricating fluid. intothe pumping column. The

Houter pipe,fis.in this-.instanceshownas well, pipe |02. .Theinner .tubeisfs'hownat |42. andfethe lowerpart of .the 'pump rod, -solid i. in .this-instance, is l.shown at 22. A s pecialftting-B .is inserted `in thevlengthoftube |42.and carries valvular means 602 whichopens toallow passage of lubricating uid fronithe.tube .|42 into-the pumping column in pipe .|162 but tvcloses.against passage ofi-fluid in the opposite direction. `..T,his valvular. means is. inserted in .tube |.42..above .the packing unit..352. y -Below the v packingunitlthe lower extension y| 42a of.. the .tube .has the .opening 312V and carries the packer |09. The remainder of the pumping mechanismis nothere illustrated asit is or may be the same .as showntor instance-in'Fig. 4.

.All of. .the foregoing apparatus designs have been designed in particulars to :suit a `pumpfoi the. type known as a tubingpump; .that .is, one

in which the pump barrelislowered wththe Y tube which .surrounds the .rods-'or gin usual pumping practice is .lowered withlthe tubing.

Figs.` 7 .and 8 show .a design of myapparatus specicallyadapted for utilizing a-` pump ofthe type known. as an insert pumpwherelthe whole pump apparatus, includingl the .pump'barreL is Y into the space between',V pipe w3 and tube' |43.

The pump barrel or liner M3, inthisiform of the, apparatus, extendsfon upwardly ,asl illustrated, and it has openings'3l'3a registering withopenings' 313.

Hollow .pump rod`2'13,.equipped withthe downwardly opening valve .693. which acts' like.that of Figs. 3 and 4, extends upwardly'from .pump

.plunger 293 for some4 distance .andatlits upper end, wherelit hasthe openingsor. perforations vl2&3, itis joined tothe pump rodv |23.

..1n this form ortho apparatus. I.providea packing. which` forms afseal between'. the.,up

wardly extended .pump linen-.433 jand' .r'od l'2713,

.to perform'the same .generalfunction which is performedbypacking of Fig.,3. InlFigs. 'land 8 however I show a different form of packing. And I also -provide Vanotherpackingor'seal to close .oi the. space .between pump? liner i483.. and

tube |43` to` preventthe lubricating.. uidfrom passing Ydownwardly around liner4|l3 `.andthus into the pump columnwithout being controlled by valve 603. Y

The first mentioned packing ishere shownas being in theform ofa series of` tubular -metal linersimmediately surrounding `pump rod 313 andi held endwise ,between ,.a ".shoi'il'der.v ring.' `84 which is xed in pump liner 403 and the lower end 83 of a packing carrying fitting 02 which is threaded into the upper end of pump liner 403. The liner sections 35 are held in a sleeve 8| which is also confined endwise in the same manner. Other details of this type of metal liner packing are well known and need no further description.

The fitting 32, at the upper end of the pump liner 403, carries a seal 80 of the well known double flange type which is expanded `by pressure. Seals of this type are usually made of metal or leather and are expanded by pressure exerted upon them in either direction. When expanded by the pressure of either the lubricating iluid or of the pumping column, this seal will sealingly engage the inner wall of tube |43; but when the pressures are relieved the seal will be loose so that it, together with the other parts of the apparatus, may be withdrawn upwardly through tube |43.

Some means is provided for limiting the upward movement of the pump rod and plunger above the normal pumping stroke with relation to the pump barrel or liner. For instance, this may be provided by an upwardly facing shoulder 213a on rod 213 adapted to engage shoulder ring 84. To remove the whole pumping apparatus, including the pump barrel from the well, it is only necessary to pull upwardly on the pump rods, and when shoulder 213e engages shoulder ring 84, the pump barrel and all parts connected with it will be lifted off the pump barrel seat 4| 3, so that the whole pump apparatus may be removed from the well on the pump rods. Correspondingly, the whole pump apparatus may be inserted in the well on the pump rods.

One of the characteristics of the several structures described is that the pump (the pump barrel) in operative position is carried or supported on the inner tube and that, regardless of how the pump barrel is so carried, there is an eiective seal between the outer tube and the pump barrel. It is that seal that functionally associates the pump (the pump barrel and the standing valve) with the outer pipe by forming a base for the pumping column in the outer pipe. In the several described structures, the seal is formed in different manners. In Figs. 7 and a where the pump barrel proper is mounted Within a lower extension of the inner tube, the seal between the outer pipe and the pump barrel is physically formed of the seal between the outer pipe and the inner tube, and the seal (or fit) between the inner tube and the pump barrel proper. In Figs. 1 to 3 and 4, 5, where the pump barrel proper forms a lower extension of the inner tube, the seal is a single one directly between the pump barrel (or the tube) below openings 31 or 31|. In Figs. 1 to 3, the seal is formed by the pump barrel fitting in the outer pipe (the tubing). In Figs. 4 and 5 the seal is the packer |00. In any of these cases it is only necessary that the seal be below openings 31, 31|, 312 or 313, and consequently the seal may actually contact either the pump barrel proper or the lower part of the inner tube. Seeing that the function of the seal is to associate the barrel with the outer pipe, the seal will be broadly referred to as a seal between the barrel and outer pipe, and for that purpose the barrel will be considered broadly as extending up to the openings 31 etc.

I claim:

l. Apparatus for pumping liquids irolm wells comprising the combination of, an outer pipe extending from the surface down into the well, a rod-operated pump of the reciprocating displacement member type associated with the outer pipe and adapted to raise a column of Well luid through that pipe to the surface, a pump operating rod extending down within the outer pipe and connected to the displacement member of the pump to operate it by vertical reciprocation, an inner tube immediately surrounding the pump rod throughout a substantial portion of its vertical length, an imperforate piston xedly mounted on the pump rod to reciprocate with the rod in and near the lower end of the inner tube above the displacement member and exposed on its upper face to the pressure of iiuid above it in the inner tube, and means for maintaining a body of relatively non-viscous fluid above the piston in the inner tube around the pump rod at a pressure which at least substantially balances the pressure of the well iiuid column at the lower end of the inner tube.

2. Pumping apparatus as dened in claim l and also including means for supplying non-viscous fluid under pressure to the upper end of the inner tube, and valvular means operated in consonance with the reciprocation of the pump rod and controlling the supply of said iluid under pressure.

3. Pumping apparatus as dened in claim 2 and in which there is a passage communicating the interior of the inner tube above the piston with the wellA iluid column in the outer pipe, and a loaded check valve controlling said passage and opening at a predetermined pressure to pass uid from the interior of the inner tube to the pump column.

4. Pumping apparatus as dened in claim 1 and in which there is a passage communicating the interior of the inner tube above the piston with the well fluid column in the outer pipe, and a loaded check valve controlling said passage and opening at a predetermined pressure to pass fluid from the interior of the inner tube to the pump column.

MARCUS W. HAINE'S.

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

UNITED STATES PATENTS Number Name Date 1,206,706 Holmes Nov. 28, 1916 1,376,877 Herron -l May 3, 1921 1,412,146 Stone Apr. 1l, 1922 1,614,865 Boden Jan. 18, 1927 1,901,031 Humason Mar. 14, 1933 2,530,673 Zinszer Nov. 2l., 1950

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