US2605712A - Hydraulic pumping system for producing from overlying reservoirs - Google Patents

Description

Aug. 5, 1952 L. F. DAVIS ErAL HYDRAULIC PUMPING SYSTEM FOR PRODUCING FROM OVERLYING RESERVOIRS 4 Sheets-Sheet l Filed Nov. 6, 1948 all 0. 0am

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L. F. DAVIS, ET AL Aug.y 5, 1952 HYDRAULIC PUMPING SYSTEM FOR PRODUCING FROM OVERLYING RESERVOIRS 4 sheets-sheet 2 Filed Nov. 6, 1948 U2-57' ma (fd-fm Aug- 5, 1952 F. DAvls ET AL 2,605,712

HYDRAULIC PUMPING SYSTEM FOR PRODUCING FROM OVERLYI'NG RESERVOIRS Filed Nov. e, 194s 4 sheet's-sneet 3 Aug. 5, 1952 L. F. DAVIS ET AL HYDRAULIC PUMPING SYSTEM FOR PRODUCING FROM OVERLYING RESERVOIRS Filed NOV. 6, 1948 4 Sheets-Sheet 4 Har-r Mdnsbur J1: Mar.:- alld'rarpb ler' jaw/5ML Patented Aug. 5, 1952 HYDRAULIC PUMPING SYSTEM FOR PRO- DUCING FROM OVERLYING RESERVOIRSI ALouis F. Davis, Harry N. lStansbury, Jr., and

Marshall O. Crumbaker, Dallas, Tex., assign'ors to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania Application November 6, 1948, Serial No. 58,652

This invention relates to an improved system for producing from a plurality ofsubterranean oil reservoirs. More particularly, the invention relates to a system including hydraulic'pump means for producing from a plurality of oil reservoirs through a single well without comminglmg of the fluids from the several reservoirs.l Y g The search for oilhas led to the discovery 1n certain oil fields of a number of producing zones.

Generally. the characteristics of these producing zones are dissimilar and frequently both oil and gas reservoirs are encountered. In the casejof oil reservoirs, to which the present invention 1s primarily directed, the pressure exerted on the oil contained therein may be attributable to a water drive, for example, or the presence of dissolved gaseous hydrocarbons. Further, there may be a considerable variance in the quantum of pressure exerted on the various reservoirs 1n the field.

Joint production of oil from two or more producing zones through a single casing or tubing string is likely to result in irreparable damage of the reservoirs and wastage of the uids contained therein due to drainage of fluid from one reservoirinto a reservoir of lesser pressure and the attendant pressure drive reduction in the former. For the above reasons and the fact that in substantially all States in which oil is being produced from subterranean petroliferous zones laws have been enacted imposing restrictions on the production of loil and'gas, or either, asthe case may be, from two or more Vproducing zones in an oil field, efforts have'been directed tothe development of a method and apparatusffor 1ndependently producing oil from a plurality of overlying reservoirs.

Obviously, this could be accomplished by producing separately each of the reservoirs through a well or wells communicating solely therewith;

however, relatively high drilling costs make desirable the production from the producing Zones through a single bore hole. In this regard, little difculty is experienced in the case of reservoirs having sufficient pressure exerted thereon by a Water drive, for example, to produce thel same without employment of artificial lift means. For this purpose a tubing string having a packer provided on the end thereofv is run into a bore hole which traverses the reservoirs and is lined with a well casing having periorations therein communicat-ing with each of the reservoirs. The well packer is set intermediate Van upper and lower producing zone, whereby uid from the upper producing zone will ow into the well casing and 7 Claims. (Cl. 10S- 46) v thence to the well surface through they annular space between the casing and tubing string, and uid from the lower producing zone will be directed into the tubing and will flow ltherethrough to the well surface. As the reservoirs are produced, the reservoir pressures will be reduced and this will continue until the pressure drives are insuicient to cause fiuids contained therein toflow to the well surface. Natural flow having ceased, the reservoirs may thenvbe put on artificial lift to recover an additional amount of reservoir fluid. The same situation obtains in the case of rreservoirs in which the initial pressure is insufficientv topermit natural flow of reservoir iluid. V t

A modification of the system described above, which has been proposed for producing sepa. rately from two or more reservoirs having pressures such as to require artificial lift means, utilizes gas lift valves operable upon the establishment of a preselected differential in pressure thereacross'. In this system, an rinner tubing string is run inside the outer tubing string in a manner to provide an annular space therebetween and a packer is set externally of the inner tubing string and adjacent the lower end thereof, in a manner sealing the annular space betweenit and the outer tubing string, whereby reservoir fluid from the lower reservoir instead of viiowing upwardly in the outer tubing string, as in the previous system, will be directed upwardly into the interior of the inner tubing string.- Pairs of oppositely disposed gasV lift valves are provided at spaced intervals respectively in the walls of the inner and outer tubing strings for lifting independently reservoir iiuid from the lower reservoir and the upper reservoir, respectively. The gas lift valves may be actuated by injection of gas under pressure into the yannular spacebetween the inner and outer tubing strings. The valves are adjusted so as to be actuated by decreasing pressure differentials from the uppermost down to the lowermost pair of valves. The gas is injected at a pressure sufli- Cient to actuate the uppermost pair of valves whereby the gas will vpass therethrough and lift to the well surface the reservoir fluids above the uppermost pair of valves. In a similar manner, succeeding pairsof gas lift valves are actuated until the reservoirA fluids above the lowermost pair of gas lift valves have been raisedto the well surface. In practice, this system is unsatisfactory because the gas pressure at which the gas lift valves are actuated is dependent upon the pressures of the reservoir fluids in the annular space between the outer tubing string and the casing, on the one hand, and within the inner tubing string, on the other hand, and, therefore, only partial control of this system from the well surface is possible. Further, in order to repair or replacel the -gaslift valves it is necessary to pull both the innerand outer tubing strings.

Other systems have been proposed for producing independently a plurality of producing Zones through a single bore hole but none of these systems are entirely satisfactory for Various reasons.

Accordingly, one object of the invention is to provide an improved system for producing from a. plurality of subterranean reservoirs through a single bore hole, and a system thatwill obvia-te the difficulties above set forth.

Another object of the invention is to provide a system for producing from a plurality of producing zones through a single bore hole without commingling of the fluids from the several zones.

A further object of the invention is to provide a system for producing from a plurality of producingsones, the operation of which system may be controlled entirely from the surface of the well.

A further object of the invention is to provide a system includiing hydraulic pump means for separately lifting to the well surface reservoir fluid from a plurality of subterrancancil reservoirs through a single bore hole.

Other objects` and features will be apparent from the drawings and description which follow.

Figures 1, 2, 3, and 4 are viewsQpartially in section and partially in elevation, representing sequentially a well installation of apparatus constructed. in accordance with the present invention.

Figure 5 is a cross-sectional lview taken along the line 5 5 of Figure 6.

Figure 6 is a fragmentary, vertical cross-secF tional view taken along,T the 'line G B of YFigure 5 showing in detail the manifold nipple of the secondary casing.

Figure 7 is a cross-sectional view taken along the line 1 1 of Figure 6.

Figure 8 is a cross-sectional view taken along the line 2 3 of Figure 9.

Figure 9 is a fragmentary, vertical cross-sectional view taken along the line 9 53 of Figure 8 showing the upper shoe.

Figure 10 is a cross-sectional view taken along face of the earth in which is run a bore hole including casing 2 traversing oil reservoirs 3 and 4, communicating with the interior of casing 2 through perforations 5 and 6, respectively. It is the purpose of the present invention to produce a plurality of reservoirs through a single bore hole and in particular at a time when the reservoir pressures are insufficient to cause the fluid to flow to the well surface except with the use of artificial lift means. It is also the pur- 4 pose of the present invention to utilize hydraulic lift means as the artificial lift means and in a manner such that the fluids from the several reservoirs will not be commingled.

To accomplish these results, there is disposed within casing 2 a rst tubing string 'l in a manner providing a rst annular space 8 between it and casing 2, and a second tubing string 9 within -the rst tubing string in a manner providing a second annular space Il) between it and the first tubing string 1. As will be seen in Figures 3 and 11, the second tubing string 9 is terminated short of thefrst tubing string I and at its end is provided with conventional ball check valve II for permitting the flow of fluid in one direction upwardly into the second tubing string 9. Also disposed within second tubing string 9 are hydraulic lift pumps I2 and I3, shown in detail in Figures 12 and 13, respectively, the two pumps being identical in construction with the exception of the end fittings securing them within the tubing string, the pump I2 as exemplied in Figure 12 being shown with its pistons in the lowermost position and pump I3 as exemplified in Figure 13 being shown with its pistons in the uppermost position.v The construction and operation of these pumps will be hereinafter described.

In Figure 4, it will be noted that rst tubing string 'I is terminated short of the end of casing 2 and preferably at a point abovevupper pro-ducing reservoir 3 to permit the inclusion of flow direction means for initially directing the flow of iiuid from the several reservoirs 3 and 4, which flow direction means may consist of any one of several known mechanisms. The iiow direction means exemplied in Figure 4 utilizes the conventional crossover packer mechanism. However, it will be apparent to persons skilled in the art that an anchor type packing mechanism may be employed with equally good results.

Tre crossover mechanism shown in Figure 4 comprises nipple I4 which is threaded as at I5 to the end of iirst tubing string 1, and as at I6 to sleeve Il which terminates in ball check valve I8 for permitting the Iiow of fluid in one direction upwardly into sleeve I'I. at I9 to nipple I4 is expander 29 for cooperation with resilient packing element 2l secured as by bolts or rivets 22 to skirt 23. Screen 2t is threaded as at 25 to skirt 23 and is xedly secured with respect to casing 2 by the expansion of production packer 26 placed intermediate producing reservoirs 3 and 4. Annular ring 21 is rigidly secured to sleeve l'! and cooperates with shoulder 28 of skirt 23 to support skirt 23 and packing element 2l free of expander 2] at the time of lowering rst tubing string I and its dependent crossover mechanism into the well and until such time as production packer 2S is expanded, whence screen 24 and consequently skirt 23 will be frictionally held in fixed position for continued movement of expander 2D into packing element 2 I. Expander 20 will expand packing element 2| tightly against the inner wall of casing 2 and at the limit of its movement will be brought to rest, as at 29, against the endof-skirt 23.

Further, in reviewing Figure 4, it will be seen that the uid from reservoir 4, by reason of packer 26, will be directed through openings 3l! of screen 2d and that also due to the presst of shoulder EI 0I" skirt 3 against the outer wall of sleeve Il, will be directed through check'valve i8 into sleeve i' and thence through port 32 in nipple I into annular space 33 between the rst Also, threaded ask v tubing string 1 and a secondary-casing 34. Secondary casing 34 is pressed fitor'otherwise rigidly securedas by threading, as at 35, to nipple I4 and continues upwardly within casing 2 to a point intermediate lower hydraulic pump I3 and upper hydraulic pump I2, at which point it is terminated in a closed end `as 4by ia pressed fit against manifold nipple 31, which nipple, as seen in'Figure 6, also serves to secure successive sections of first tubing string 1, as at 38 and 39.

The fluid entering annular space 33 will continue to flow upwardly therein until reaching openings 40 in first tubing string 1 `(Figures 2 and 6), where it will pass intoy the interior of first tubing string 1, and by reason of O-rings 36 and 4I and manifold nipple 31 will be further directed through openings 42 in second tubing string 9 into the interior thereof. The iiuid entering into the interior of second tubing string 9 by. reason of a block formed by header 43, as shown in Figure 9, again will be directed upwardly and into fluid chamber 44 on the intake side of hydraulic lift pump I2, the housing 45 ofwhich is threaded on its intake side, as atv 46, and on its power side, as at 41, to tubing string 9.

It will be noted that the openings 40 and 42 are positioned in tubing strings 1 and 9, respectively, intermediate the two hydraulic lift pumps I2 and I3. Attention is also calledto the fact that O-rings, such` as ring 36, are conventional and are in common use in the industry, yand are typical of a number of such devices for'sealing the annular space between two tubes.

The O-ring 36 is secured in place by commonly used assembly comprising, for example, nipple 48 lprovided with integral annular ring 49 against course, that gasket 59 serves to .prevent leakage of fluid through the threaded fittings for holding the O-ring in place.

The power liquid to pump I2 is supplied from a source, not shown, through valve controlled pipe 54 communicating with theinterior of second tubing string 9 and, successively, with the power end of hydraulic pump I2 through openings v55 in screen 56 threaded, asat 51, into the pump housing 45. Pumps I2 and I3 are of the type generally known as Kobe sub-surface production unit, and the construction vand operation of which may be described as follows.

Referring to Figures 12 and 13, and in particular at this time to Figure 12 in which the pump is shown as having completed its down Stroke, it wlil be seenthat the power fluid entering through openings 55 of screen 56 will flow into chamber 58 and through passage 59 toapply pressure to head 69 of piston 6|. It is to be understood that by down stroke is meant movement of the piston from the upper end of the cylinder, as shown in Figures 1,2 and 13, to the lower end thereof; and by up-stroke is meant movementr ofV the piston in the opposite direction. During the down stroke of piston 6 I, the power iluid previously applied against head 62 of piston6| for up--stroke movement is exhausted through passage 63 into annular opening 64 provided by valve 65 and However, upon movement of piston 6I to the end of its down stroke, the power fluid in chamber 58 is caused to flow by reason of reduced head 61 of piston rod 68 through port 69 and into the space 1I) beneath valve 65, whence valve 65 is caused to move upwardly whereby communication between passage 59 and chamber 58 and4 also between passage 63 and-port 66 is broken, and simultaneously the annular opening 64 of valve 65 is moved adjacent passage 59 to establish communication between passage 59 and port 66, and port1l in valve 65 is moved adjacent passage 63 to `establish `communication between chamber 58 and passage 63. When valve 65 is in its uppermost position it will be seen that the power iiuid then Awill be caused to move from chamber 58 through port 1I and passage 63 and to be applied against head 62 lof piston 6|, whereby pistonv 6I will be caused to move to its uppermost position rand the cycle repeated. vIt will loe-noted that valve 65` is limited in its downward movement by engagement of shoulder 12 against flange 13 formed integrally within housing 45. kkDuring movement of piston 6I to its uppermost position, communication between chamber 58 vand port 68 willbe sealed by upward movermerit of piston rod 68. However, valve 65 will remain inits uppermost position until movement of piston 6| to the limit of its up-stroke whence annular 'cut out 14 in rod 68 will move `intov registry` simultaneously vwith port 69 and bleed port15 which together with the pressure of thepower fluid against end 16 of valve 65 will cause the latter again to be moved to its lowermost position. It alsdwill be noted that during theup-stroke of piston 6I, the powerfluid previously applied against head 60 thereof will be caused to ow through passage 59 and annular opening 64, andV through port 66 into annular space I0.

Pumppiston 11 ,is integrally connected with power ,piston 6I by middle rod 18 and will be caused to operateA vin lsynchronism therewith. During Vthe down stroke of piston 11, the reservoir fluid in chamber 44 will be drawn through passage 19 past ball ,check valve 80 and into cylinder 8|. Also, `during the down stroke of pis-- ton 11, the fluid from chamber 44 previously drawn into cylinder BI at the time of the upstroke of piston 11 will be forced through passage 182 past yball check valve 83 and into annular space kIII.' v During the up-stroke of piston 11,

' check valves 88 and 83 vwill be seated by the pressureof fluidthereagainst, and at suchtime the fluid previously moved intocylinder 8| during thedown v stroke .of .piston 11 `will be forced 'throughp-assage 84l past ball check valve 85 and into annular space I0 and simultaneously additional iiuid will be rdrawn through passage 86 past check valve 81 and into cylinder 8|.

' with fluid, will serve to cushion movement of pistons 6I and 11.

Y The operation of lower pump I3 is identical withthat of upper pump I2 and differs therefrom in the drawing only in that the pumpingmechabetween skirt 23 and sleeve I'I.

. 7 nism of pump I3 is shown in Figure 13 lat the end of its up-stroke, whereas pump I2 is shown in Figure 12 at the end of its `down stroke. Upon repetition of the cycle of operation of hydraulic lift pump I2, the -spent power fluid and also the packer 26. Such being the case, it will flow upwardly in casing 2, whence it will pass through openings 9S in skirt 23 into annular space 91 The fluid then will be directed through `passage 98 provided in nipple I4 and into rst tubing string 1. However,

by reason of lower shoe 99 threaded, as at |00 andas at IBI, to successive sections I62 and |03 of first tubing string 'I and also sealed, as at |04, against the end of second tubing string 9, it will be noted that continued passage of the fluid up- Vwardly into first tubing string 'I will be blocked and that instead such fluid will be directed through check valve Il and into the intake end IUE of lower hydraulic pump I3 through the medium ofv landing nipple IBB in which hydraulicV pump I3 is seated-within second tubing string 9.

The operation of hydraulic pump, I3 is identical with hydraulic pump I2, and is adapted to -lift to the well surface fluid from upper reservoir 3. By reference to Figures l to 3, inclusive, and in particular to Figures 5 to 1l, inclusive, of the drawings, it will be Seen that the power fluid to pump I3 is admitted froma source, not shown, through Valve controlled pipeY I'I which is run initially into first annular space 8 and thence through annular space 33, and terminates as by threading, as at IOS, `in `upper shoe |99 in communication with interconnecting kpassages IIil and III. From passage III the fluid will pass into second annularspace yIII, and due to O-ring 6I and O-ring I I2 will be caused to enter through a Series of ports H3 provided in header 43 into interconnecting longitudinal bore I I4 and sleeve H5 and thence into the power side II6 of hydraulio pump I3.

Also by reference to Figures 1 to 3, inclusive, and in particular to Figures 5 to 11, inclusive, of the drawings, it will be seen that the fluid from reservoir 3 exhausted from hydraulic pump I3 will empty into that portion of second annular space IG between O-ring II2 and landing nipple I, whence it will be directed throughinterconnecting passages II'I and II8 provided in lower shoe 99 and through pipe H9 threaded as at IEB in shoe S9. PipeV I I9 continues upwardly in annular space 33 to a point above manifold nipple k3l whence it is terminated'in a free end i'2I in first annular Space 8,as shown in Figure 6. The fluid delivered from pipe I I9 will continue to be forced upwardly in annular space 8 Ythrough the action of hydraulic pump I2, and upon reaching the well surfacev/ill be drawn oif through valvecontrolled pipe |22.

Although any suitable, available liquid may be employed as the power liquid, it is preferable to employ clean crude oil which 'previously has been produced from the reservoirs. This not only provides a readily available source of power liquid but also obviates the vproblem of separating the '-commingled' power 'liquid and reservoir Aliuid producedfromth'e well.

Each of the hydraulic pumps are disposed at a suitable position along the' length of the seclond-v tubing string such that fluid from its associated reservoir can enter the pump chamber during operation of the pumppiston. It is understood `that the power liquid is under sufcient pressure to actuateeach of the pumps against the back pressure exerted thereupon by the col- V'urnnof liquid exhausted therefrom.

It is also understood that the invention is not to be limited to the particular hydraulic pump illustrated, but that any suitable conventional hydraulic pumping means may be employed.

We claim: y

l. In a system for producing from a plurality f subterranean vreservoirs through Va single bore hole'traversing the reservoirs and including a well casing' disposed inthe bore hole and provided with perforations adjacent an upper and a lower reservoir, and a'first tubing string Adisposed in vthe well casingin a manner to provideva first annular space therebetween, the combination of a second tubing string disposed in the first tubing string in a manner to provide .a second annular space therebetween and havingV connected intermediate its lengthfand at the lower end thereof respectively an. upper hydraulic pumping means vhaving exhaust ports inthe walls thereof, and a header from which issuspended a lower hydraulic pumping meanshaving exhaust ports in the walls thereof, each of said hydraulic pumping means'being operable upon the application thereto of power liquid to lift to the surface of the earth reservoir fluid entering thereinto, meansA forY directing .the flow of uid from the -upper reservoir into one of the pumping means, means for directing the flowof fluid v.from the lowerreservoir into the other pumping means, means for applying power liquid to the upper andl lower pumping means under suiflcient pressure to operate the pumps, packing means for isolating the exhaust ports of the upper and lower pumping means, means for directing flow of fluid exhausted from the upper vpumping meansA upwardly through the second annular space, and means for directing the flow of fluid exhausted from the lower pumping means upwardly, through the first annular space whereby reservoir fluids from the upper and lower reservoirs will bel lifted to the surface of -the earth, without the comminglingv thereof.

2. In a system for producing from a plurality of subterranean reservoirs through a single bore hole traversing the reservoirs and includingY a well casingdisposed in the bore hole and provided with perforations adjacent anupper and a lower reservoir, and a first tubing string'disposed in the well casing in a manner to provide a first annular space therebetween, the combination of a second tubing string disposed in the first tubing string in a manner to provide a second annular space therebetween and having connected intermediate its length and at the lower end thereof respectively an upper hydraulic pumping means having exhaust ports in the walls thereof, and a header from which is suspended a lower hydraulic pumping meanshaving exhaust ports in the walls thereof, each of said hydraulic pumping means being operable upon the application thereto of power liquid to lift to the surface of the earth reservoir iiuid entering thereinto, means for directing the now of fluid ,from the upper reservoir into one of the pumping means,

means for directing the fiow of fiuid from the lower-pumping means, means-associated with thel exhaust ports of the upper pumping means .for directing the flow of fluid exhausted therefrom upwardly through the second annular space, and means associated with the .exhaustports of the lower pumping means for directing theflow of fluid exhausted therefrom upwardlythrough the first annular-space whereby reservoir fluids from the-upper and lower reservoirs will be liftedto thesurface of the earth, without the-"com-gVV 3. In a system for producing from a plurality of subterranean reservoirs-through a single bore hole traversing the `reservoirs andv including a well casing disposed in the bore hole and provided with perforationsr adjacent an upper and a lower reservoir, and a first tubing string disposed in the well casing in a manner to provide a first annular space therebetween, the combination of a second tubing string disposed in the first tubing string in a manner to provide a second annular space therebetween and having connected intermediate its length and at the lower end thereof respectively an upper hydraulic pumping means having` exhaust ports in the walls thereof, and a header from which is suspended 'a lower hydraulic pumping means having exhaust ports in the walls thereof, each of said hydraulic pumping means being operable upon the application thereto of power liquid to lift to the surface of the earth reservoir fluid entering thereinto, means for directing the iiow of fiuid from the upper reservoir into the lower pumping means, means for directing the flow of fluid from the lower reservoir into the upper pumping means, means for applying power liquid to the upper pumping means through the second tubing string, a third tubing string disposed in the first annular space and adaptable for applying power liquid to the lower pumping means, packing means for isolating the exhaust ports of the upper and lower pumping means, means associated with the exhaust ports of the upper pumping means for directing the fiow of fiuid exhausted therefrom upwardly through the second annular space, and means associated with the exhaust ports of the lower pumping means for directing the flow of fluid exhausted therefrom upwardly through the first annular space whereby reservoir fluids from the upper and lower reservoirs will be lifted to the surface of the earth, without the commingling thereof.

4. In a system for producing from a plurality of subterranean reservoirs through a single bore hole traversing the reservoirs and including a well casing disposed in the bore hole and provided with perforations adjacent an upper and a lower reservoir, and a first tubing.` string disposed in the well casing in a manner to provide a first annular space therebetween, the rcombination of a second tubing string disposed in the first tubing string in a manner to provide a second annular space therebetween and having connected intermediate its length and at the lower end thereof respectively an upper hydraulic pumping means having exhaust ports in the walls thereof, and a header from which is suspended l0-` a lower hydraulic .pumping means having exhaust ports in the walls thereof, each Vof said hydraulic pumping means being operable upon the application thereto of power liquid to lift to the surface of the earth reservoir fluid entering thereinto, meansfor directing the flow of fluid from the upper'reservoir into the upper pumping means, means for directing the flow of fluid from the lower reservoir into the lower pumping means, means for applying powerliquid to the upper pumping means through the second tubing string, a third tubing-string disposed-in the first annular space and adaptable for applying power liquid to the lower pumpingv means, packing means `for' isolating the exhaust ports of the upper andrlowervpumping means, ymeans associated with the exhaust ports of theupperl exhausted therefrom upwardly through thesec-` Lond annular space, and means associated with the exhaust ports of Lthe lower pumping means for directing the flow of fluid exhausted therefrom upwardly through the first annular space wherebyreservoir--fiuids from vthe upper andl lower reservoirs Ywill be lifted to the surface of the earth, .without the commingling thereof.

5. In a system` for producing independently from twov subterranean reservoirs through a single well including a well head, a casing traversing the reservoirs and f communicating therewith, a first tubing string disposed in the casing'in a manner to provide a first annular space therebetween, and a secondtubing string disposed in the first tubing string inra manner to provide a second annular space therebetween, in combination therewith a rst and a second hydraulic lift means, each having a power liquid and a reservoir uid inlet and exhaust ports,

the power fluid inlet of the first lift means being connected to the second tubing string whereby power fluid may be delivered through the second tubing string to the first lift means and the exhaust ports of the first lift means communicating with the first tubing string through which exhausted iiuid is conducted to the well head, means associated with the reservoir iiuid inlet of the first lift means for directing fluid from one of the reservoirs into the first lift means, a third tubing string disposed in the first annular space and communicating with the power liquid inlet of the second lift means for conducting power liquid to the second lift means, means for directing fiuid from the other reservoir into the reservoir fluid inlet of' the second lift means, and means communicating with the exhaust ports of the second lift lmeans for conducting fluid into the first annular space through which such fluid flows to the well head.

6. In a system for producing independently from two subterranean reservoirs through a single well including a well head, a casing I traversing the reservoirs and communicating therewith, a first tubing string disposed in the casing in a manner to provide a first annular space therebetween, and a second tubing string disposed in the first tubing string in a manner to provide a second annular space therebetween,

' in combination therewith a first and a second the first annular space and communicating withV the power liquid inlet of the second lift means for conducting power liquid to the second lift means, means for directing uid from the other reservoir into the reservoir iluid inlet of the second lift means, and means communicatingv with the exhaust ports of the second lift means for conducting fluid into the first annular space through which such uid flows to the Well head.

7.- In a system for producing from a plurality of subterranean reservoirs through a ,single well including a casing 'securedl within theV well and traversingthe reservoirs, aA-drst` tubing string disposed within the casing in a manner provid-y ing a rst annular space between it and the casing, a secondrtubing string disposedl within theA rst tubing string in a manner providing a second annular space between itand the rst tubing string, a rst hydraulic lift means rinterposed in said secondV string intermediate itsiends, a second hydraulic liftl means suspended from the lower end of said second string, each of said hydraulic lift means having power liquid inlet and outlet ports and welliluid inlet and outlet ports, means providingVv communication between one of said reservoirs andthe well'fluid inlet port of one of said lift means, means providing communication betweeny another ofsaid reservoirs and the VWell uid inlet port of the other of said lift means, packing means for isolating the well fluid inlet ports of the two lift means from each other, means comprising the interior of said second string for supplying power liquid from the top of the well to the power liquid inlet port of one of said lift means, means comprising a third tubing string disposed in the rst annular space for supplying power liquid to the power liquid inlet of the other of said lift means, packing means for isolating the power liquid inlet ports of the two lift means from each other, means for directingtheflow of fluid exhausted from the exhaust portsof one of said lift means upwardly through the first, annular space,A means for directingthe ilow of uid exhausted from the exhaust ports of the other of said lift means upwardly through the second annular space, andv packing means for isolating from each other the,

fluids eXhauSted by the two liftmeans.V

LOUIS F. DAVIS. HARRY N. STANSBURY, JR. MARSHALL O. CRUNLBAKER.

, REFERENCES oigan rShe following references are of record in the ille or" this patent:

UN ITED' STATES PATENTS

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