US2129090A

US2129090A - Gas lift pump

Info

Publication number: US2129090A
Application number: US61393A
Authority: US
Inventors: James E Hoover
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-01-29
Filing date: 1936-01-29
Publication date: 1938-09-06
Anticipated expiration: 1955-09-06

Description

Sept. 6, 1938. J. E. HOOVER GAS LIFT PUMP lFiled Janl 29, 1956 2 Sheets-Sheet 1 J. E. HOOVER GAS LIFT PUMP Sept. .6,` 1938;

Filed Jan. 29, 1936 2 Sheets-Sheetl 2 INVENTOR.l I JAMES E. HOOVER ATTORNEYS.

Patented Septc 69 `1938 einem Unirse STATES PATENT orales GAS LIFT PUW James E. Hoover, @Mahoma City, Ghia.

Application January 29, i936, Serial No. 61,393

1l Claims.

This invention relates to apparatus for raising liquids from wells.

More specically the invention relates to an improved gas lift pump for raising liquids such as oil or water from deep wells.

A further object of the invention is the provision of a device which will raise a volume of liquid from a well with a satisfactory gas-liquid ratio.

be used to operate the apparatus.

Liquids, compressed air, compressed vapors, etc., are contemplated as actuating lfluids.

It is the usual practice upon cessation of normal flow from a well resulting from a diminution of the rock pressure existing in the producing strata or reduced gas content of the fluid within the formation, to employ a gas lift to sustain and increase the flow or production of the well.

The gas lift method, either continuous or intermittent, as will be understood by one skilled in the art, comprises the introduction of a gas, generally under pressure, into the well to aid the oil flow by aerating or lightening the fluid column and thereby enabling the lowered rock pressures existing at that time to overcome the hydrostatic head of the uid column and thereby to continue the flow.

face.

It has been the general practice in the past to employ a pumping device of the so called sucker rod type. .The limitations of a pump of this type are Well recognized in the art.

In deep wells structural limitations are encountered because of the stretch inherent in any steel which will resist the corrosive effects of the fluids encountered in the Well.

A second limitation of a serious na- (Clu HB3-240) ture is the size'and Weight of the machinery at the well surface necessary to reciprocate many thousands of feet of sucker rod of sufficient size to sustain its own weight and a column of liquid of equal'length.

A third limitation of considerable importance is the sand cutting of pumps of this type. After a well has ceased to flow naturally under normal rock pressures or under the gas lift method, the remaining gas pressure from the producing formation is sufficient in many instances to maintain the liquid in an agitated condition with the result that considerable sand will be contained in suspension in the liquid. This sand exerts a very detrimental abrasive action upon the pumping elements with which it comes in Contact. because it is under the large hydrostatic head of the liquid column. It therefore is obvious that moving parts requiring fairly close fits soon will become worn to an extent that they are no longer serviceable. The pump then must be pulled from the well, at great expense, for repairs.

In applicants device the pump is actuated by gas under pressure from the well surface. The only direct connections to the surface which must be reciprocated are light rods whose sole funcn tion is to operate positively the pump valves. lt is apparent that the structural limitations encountered in the sucker rod pumps are not present in applicants device because the rods do not sustain any oil load or heavy pumping elements.A

Further advantages of applicants construction will be evident from a consideration of the specilication and claims in connection with the anneXed drawings wherein: Y

Figure 1 is a longitudinal view of applicants device in place in a well, partly in section.

Figure 2 is a longitudinal sectional view taken on the line 2--2 of Figure 3, of one embodiment of applicants device.

Figure 3 is a cross-sectional view takenv on the line 3--3 of Figure 2.

Figure 4 is a longitudinal sectional View of a device for reciprocating the valve actuating rod.

Figure 5 is a longitudinal sectional View of a second embodiment of applicants device taken on the line 5-5 of Figure '7.

Figure 6 is a longitudinal sectional view of still another embodiment, and

Figure 7 is a cross sectional view taken onthe lines 'lof Figures 5 and 6.

It should be understood that applicant has shown certain `preferred embodiments of his device in the drawings for thepurposes of illustra- Aas tion only and that other devices within the scope of the appended claims are anticipated.

Also, applicants device is not limited to use inr oil or water wells of the type shown, but may be used in other wells for raising other liquids where it is considered desirable.

Referring to Figure 1, a well casing of conventional design is shown at 20. This casing is lowered and set in the well hole by the usual methods and generally extends down to the edge of the producing strata III and cemented therein as at II, as is well understood by those skilled in the drilling art.'

A string of tubing 2| of smaller diameter than the casing 20' is then lowered therein. A second tubing string 32, which is mounted in spaced relation with the tubing string 2|, carries at one end thereof applicants improved pumping device, generally indicated at I2, and is sealed at the other end as at I3. A pipe I4 for the induction of actuating gas is mounted adjacent to and in communication with one end of the tubing string 2|.

A pipe I is in communication with the induction tube 32 and may serve to conduct pumped iiuid from the well, or operating gas to the pump, as will appear later. A machine is generally indicated at 64 for reciprocating the valve actuating rods as will be subsequently described.

Referring more particularly to Figure 2, a bull Plug 22 slotted as at 23 is fixed to the lower open end of the tubing string 2| as by screw threads 24 or by other conventional means, and rests upon or is adjacent to the bottom of the well hole and below the normal liquid level therein. A valve cage 25 is secured -as by screw threads 26 within the lower end of the tubing 2l and adjacent the bull plug 23. A standing valve 21 which may be in the form of a ball is located within the cage 25 and normally closes the aperture 28 of its own weight. Apertures 29 in the cage 25 provide for the passage of liquid from the well through the cage when the valve is in a raised position.

Applicants pumping element, generally indicated by the numeral I2, is secured to a tubing string 32 as by screw threads 33, and is lowered into the well by means of the tubing 32 which, in addition, forms a conduit for the removal of liquid to the surface.

A conical shoulder 34 is formed intermediate the length of the pump body 3| and cooperates With a seat 30 on the tubing string 2|, located at a point above the maximum liquid level in the well hole, to form a. sealed chamber 35 for the accumulation of liquid from the well.

' It will now be apparent that any liquid standing or flowing into the well hole will raise the standing valve 21. and pass into the chamber 35.

against the weight of the standing valve which is so chosen that relatively little pressure is required to operate it.

The pump lbody I2 comprises a casing 36 of generally cylindrical configuration, mounted within and spaced from the tubing 2| except at the

seat portions

30 and 34 thereby providing spaced annular chambers as at 51 and 5,8. Attached to the lower extremity of the casing 36 is a reducer 31 at one cnd of which is provided a valve cage 36 containing a standing valve 39 through which liquid within the chamber 35 may pass, under pressure, into the valve casing 36. Mounted within the valve casing 36, as by screw threads 40, is a valve cylinder or chamber 4|, provided with gas Aadmission passages 42 and liquid passages 43,

shown in Figures 2 and 3, located in an enlarged head 44 of the valve sleeve 4 I.

Gas admission ports 45 are shown in the side walls of the enlarged portion of the Valve cylinder 4| and in communication with the gas admission passages 42, and may be formed by drilling entirely through the enlarged head 44 and then plugging the aperture in the outer cylinder wall as by screw plugs 46. Other methods of forming the ports 46 will be obvious to those skilled in the art.

Other ports

41, 48 and 49 are positioned in the valve cylinder 4| at definite locations depending upon the functions to be performed, as will appear later. Similar ports or apertures 50, 5| and 52 are provided in the Wall of the valve casing 36 and in alignment with the

ports

41, 48 and 49 formed in the valve cylinder.

Tubular elements

53, 54 and 55 place the

ports

41, 48 and 49 in communication, respectively, with the apertures 50, 5| and 52. It will be noted that the apertures 50 are located in the conical seat element 34 of the casing 36. A passage 56 is provided through the seat 36 on the tubing 2| and in alignment with the aperture 50. An annular groove 56' of larger cross sectional area than the passages 56 and interconnecting the inner ends of the same is provided in the inner wall surface of the seat 30, whereby the passages 56 will be in communication with the ports 50 through the groove 56 in any relative circumferential position of the valve casing 4| within the tubing 2|. It is also apparent that the groove, because of the aforementioned difference in cross sectional area, provides for slight longitudinal misalignment of the ports 50 and passages 56 due to any inaccuracies in the machining of the

seats

30 and 34.

It will now be apparent that the valve cylinder 4| may be placed in communication with the passages 42 through the ports 45; with the annular space 59, between the tubing 2| and casing 20, through the ports 41, tubes 53, groove 56 and passage 56; and with the chamber 35 through the ports 48 tube 54 and aperture 5| and through the port 49, tube 55 and aperture 52.

A valve piston shown at 66 is slidably received within the valve cylinder-4I and has a fit suiciently snug to form an efficient seal, or if desired, suitable packing rings, not shown, may be employed. A plug 6| is suitably secured in the upper end of the piston 60, as byscrewthreads 62, in which a rod 63 is fixed in any convenient manner. Rod 63 extends to the top of the well and may be reciprocated by the device shown generally at 64, as will be developed later.

Spaced ports 65 and 66 are provided in the wall of the piston 60 which in turn communicate with annular grooves 65' and 66 formed in the outer surface of the piston. It will be noted that the grooves are larger in cross-sectional area than the ports and are continuous to provide for continuous communication regardless of circumferential or longitudinal mis-alignment as previously described.

This valve piston 4I controls the flow of an actuating iiuid such as gas or other suitable medium, and to this end the ports 65 and 66 are so spaced that in certain positions of the piston these ports are in1 communication with certain of the ports in the valve cylinder 4|. With the valve piston at the upper limit of its travel, the position indicated in Figure 2, it will be observed'that the port 48 is in communication with the port 45 through the ports 66 and 65 and a chamber 61 formed in the piston 4|. It will be apparent that in the position shown, a fluid under pressure withtiti aiaaoco in the tubing 2l may pass through the passages d2, port t5, piston port 65, chamber t'l, piston port B6, a tube 5d, aperture 5| and annular space 5b to the liquid accumulation chamber 35. Also, with the piston at the other extremity of its travel, ports tb and t5 will be Ain communication with ports tl and t@ respectively, thus providing for the passage of trapped gas in the chamber t5 through the aperture 52, tube 55, portt, port tti, chamber lil, port t5, port 4l., tube 53 and passage 5t to the annular space 59 between the tubing ti and casing til.

The valve piston t is operated ina positive manner from the welll surface by means of the rods tt which are actuated by a machine generally indicated at t4, located at the well surface.

The machine till comprises a cylinder lit provided at one end with a stuffing box tt of any conventional construction, through which the rod @t slidably passes. d piston it provided with sealing grooves 'il is slidably mounted within the cylinder tit and the rod t3 is connected to the piston liti by means of a wrist pin l2. An inlet pipe it communicates with the cylinder for the conveyance of a fluid under pressure thereinto which may be controlled by any suitable valvc means, not shown. A bleeder passage 'lit and an exhaust pipe 'lli is formed in the piston llt and an end wall 'it of the cylinder, respectively. ln practice, it may be desirable to attach the cylinder lid directly to the end of the gas induction tube El thereby eliminating the stufiing.v

box. In that case, the pipe 'lli would be eliminated and gas from the intermitter would be admitted to one side of the piston il@ through the pipe lli and would operate to force the piston downwardly due to the difference in areas of the opposite sides of the piston which produces a differential pressure on the upper surface of the piston.

lit will be readily understood that huid under pressure is admitted to the cylinder lit through the pipe liti to force the piston l@ to the upper end of its travel and thereby raise the valve piston Gili by means of the rod t3 to the upper limit oit its travel. Upon cessation of the fluid pressure supply, that portion of the fluid trapped in the cylinder tu may pass out through the bleed port 'lil and pipe l5 to a region of reduced pressure, whereupon the weight of the valve piston titl and rod @il returns the piston to the lower extremity` of its travel.

The device is generally assembled as follows: The tubing 2l with theseat 3u formed therein is lowered into the well casing 20, which already is set in the hole, until the bull plug 2t rests at or near the bottom of the well hole. The pump body t l which has been previously assembled, together with the valve piston 50 and rod 63 is lowered by means of the tubing string t2 until the seat t@ contacts the seat 30. The valve operating machine M is then attached to the upper end of the rod t3 at the Well surface.

In operation, liquid such as oil or water is -lorced from the producing strata into the bottom hole under the normal rock; pressure and builds up to a certain level in the well bottom at which time the head developed is sufiicient to raise the standing valve 21 thereby admitting theA liquid to the cham-ber 35 wherein it will assume its normal level dependent upon the rock pressure existing in the producing strata. This level will, of course, Vary in diierent wells. At this point actuating iluid under pressure is admitted to the tubing 2l at the well surface. The pressure in this tubing is generally maintained at a near constant level, dependent upon the hydrostatic head of the :duid in the eduction tube which in turn is dependent on the well depth and fluid gravity.

At the same time fluid pressure from. the intermitter is admitted to the machine tt thereby raising the rod t3 and valve piston @d in a manner heretofore'described. 'When the valve piston 6U reaches the upper limit of travel, gas under pressure in the tubing 2i passes through the passage tt, port 45, port 65, chamber til, port tt, port tt, tube 54, aperture l, annular space 5t into the ,chamber 35 above the fluid level therein. The fluid pressure exerted upon the liquid surface forces the standing valve 2li closed against the 'liquid pressure in the well and opens the standing valve 39 in the reducer di? whereby the liquid under urging by the uid pressure may pass up through the annular space between the pump casing tt and the valve sleeve di, through the ports and into the eduction tube t2.

The intermitter will generally-be set to maintain the valve piston in the raised position long enough to allow a slug of gas to pass into the eduction tube below the slug of oil thus lightening the oil column, although this is not necessary to thev operation of applicants device.

Upon closing of the input valve by the intermitter, the valve piston returns under the action of gravity to the lower extremity of its travel. In the lowered position, not shown in the drawings, the ports l5 and it are closed thus closing oif the supply of uid under pressure to the accumulation chamber, and at the same time the ports tti and @t are placed in registry with the ports lll and dt, respectively.

llt will now be apparent that that portion oi the actuating gas entrapped under high pressure in the accumulation chamber 35, may pass through the ports 52, tubes t5, ports lti, ports tt, chamber til, ports tb, ports di, tubes titl, and ports tt to the annular space t@ and thence to the surface of the well. It is evident that as this procedure taires place, the pressure in the chamber 35 is reduced to near atmospheric. At this time the standing valve 3d closes and acts as a check valve to prevent the return of liquid in the valve body di and eduction tube t2.

`When the pressure in the chamber 35 is bled to an extent that it is sufciently lower than the liquid pressure within the well bottom plus the force necessary to operate the standing valve tl, liquid from the well bottom will again flow into the accumulation chamber.

After sumcient liquid has collected in the accumulation chamber, as determined by the normal well production, the intermitter again admits fluid to the machine 64 to repeat the cycle.

It can now be appreciated that a series of slugs of/ fluid comprising actuating gas and pumped liquid will be forced up through the eduction tube to the well surface from which it is conducted to the usual separators andstorage tanks as will be understood by those familiar with the operation of such wells. y

One important advantage of` the construction described above resides in the fact that only so much of the actuating iluid as is trapped in the accumulation chamber is exhausted to the surlface. In many previous devices of this general type known to applicant, it has been necessary to bleed the pressure iluld in the entire tubing string, and since these strings may be as long as six thousand feet or more, it will be appreciated that a great amount of gas pressure will be con- 'I5V served with a consequent lowering of the fluidliquid or gas-oil ratio and a large increase in operating efficiency.

In the embodiment illustrated in'Figure 5, elements common to both devices are referred to by similar reference numerals.

In this form of applicants invention, the pump body indicated generally at 80, differs in construction from the pump body of Figure 1, and the liquid eduction tube 32 is of a larger diameter. Only those parts which differ from those previously disclosed and their mode of operation will be set forth here.

'Ihe pump body 80 is provided with a shoulder 8| having a conical seat 82 formed thereon to cooperate with the tubing seat 30 to form a seal between the annular space 58 and a chamber 83 formed between a reduced portion 84 of the pump body and the tubing string 2|, and is secured at its upper end to the tubing string 32 as by screwthreads 85.

The standing valve and

cage

38 and 39 are secured to the pump body 80 by means of a pipe 86 and union 81 provided with a shoulder 88. A packing 89 of any suitable material is placed between said shoulder and the lower end of the pump body.

A central bore 90 extends longitudinally of the pump body 80 and communicates at its lower end with the pipe 86 and at its upper end with the eduction tubing 32.

Gas inlet bores 9| are formed in the pump body 80 and extend longitudinally through the major portion thereof, communicating adjacent their upper ends with the inlet ports 92 and adjacent their lower ends With the apertures 93, the extreme lower ends of said bores being sealed by the packing 89. A series of exhaust bores 94 surround the central bore 90 intermediate the bores 9|. These bores extend from the lower 'extremity of the valve body 80 and longitudinally thereof, to a point adjacent the shoulder 8|, and communicate at one end with ports 95 formed therein. Aniannular groove 96 interconnects the outer ends of the ports 95 and is of largercross sectional area than the individual cross sectional areas of the ports 55 for the purpose set forth above in describing the groove 56. Adjacent their lower ends the bores 94 communicate with apertures 91 in communication with the chamber 35, and the extremities thereof are sealed by the packing 89.

A spider 98 is secured to the lower end of the rod 63 as by nuts 99 and lock nuts |00, or in any suitable manner. each arm of the spider 98 and is secured thereto in like manner, and is slidably mounted in bores formed in the head |02 and shoulder 3| of the valve body 80. A stung box |03 in the head |02 seals the chamber 83 from the eduction tube 32.

Slide valves |04, secured to the valve rod as by pins |05, slide upon the reduced portion 84 of the valve body and serve to close and open the gas inlet ports 92. A slide valve |06 in the form of a collar is secured to the lower ends of the valve rods |0| and is provided with valve inserts |01 suitably positioned Within the valve |06 and serving to close and open the ports 91.

It should be noted that the valve collar |06 in its lower extreme position will close the ports 91 but not the ports 93 because the inserts |01 are so -spaced to leave these ports open.

The device is assembled in the well in the same manner as that shown i-n Figure 1.

A valve rod |0| depends from l It will of course be understood that the rod 63 is reciprocated by the means and in the manner previously set forth. Also, liquid will pass into the accumulation chamber 35 as in the former device.

In operation,` actuating fluid under pressure is introduced between the tubing 32 and the tubing 2l from whence it passes into the chamber 83.

At this point the supply of gas will be cut off from the valve actuating machine, an opposite procedure to that previously described, whereupon the slide valve |04 will be lowered to uncover the ports 92 and at the same time the slide valve |06 will be lowered to close ports 91. The actuating gas may now pass through the ports 92, bores 9|, and ports 93 to the chamber 35 above the liquid level therein thus forcing the liquid through the standing valve 39, pipe 86, central bore 90 into the eduction tube 32. The gas is admitted until a slug passes into the eduction pipe below the oil slug as in the previous constructions.

Pressure gas will now be admitted to the rod actuating machine which will raise the rods, cover the ports 92 and open the ports 91. The entrapped pressure gas can now pass through the apertures 91, bores 94, ports 95, and ports 56 to the annular space 59 and thence to the well surface and atmospheric pressure. As above set forth, liquid again passes into the eduction chamber 35 and the cycle is repeated.

In the embodiment illustrated in Fig 6, the structure of Fig. is modied to permit induction of actuating gas through the central tubing string 32 and the eduction of liquid through the annular space between the tubing 32 and tubing 2|. v

To accomplish the above mentioned result, the pump body 80 is secured to the tubing 32 at the shoulder 8| as by screwthreads and the head |02 is provided with ports |08 in communication with the chamber 83. The central bore 90 extends only partially through the pump body 80 and a second port |09 places the bore 90 in communication with the annular space utilized as a. liquid eduction passage.

In operation, actuating fluid under pressure is admitted to the tubing 32 from whence it passes through the ports |08, chamber 83, ports 92 (assuming that the slide valve |04 is lowered), bores 9|, ports 93 to the accumulation chamber 35, thereby forcing the liquid therein through the pipe 86, central bore 90, and port |09 to the annular space between

tubing

32 and 2 After the chamber has been emptied of liquid and a suiiicient slug of gas has entered the eduction space, the valves |04 and |06 are operated in the manner previously described to close the inlet port 92 and open the outlet port 91, whereupon the entrapped gas in the chamber may be exhausted as described in connection with the embodiment of Fig. 5.

I claim:

1. In a device of the class described, a Well, a tubing string including a standing valve adjacent one end thereof, a seat formed in said string spaced from said valve, a second tubing string within said first named string, a pumping element on said second named string provided with a shoulder cooperating with said seat to form a chamber for the accumulation of liquid, said element having gas inlet ports formed therein, a positively operated valve'adapted to close and open said ports to control the admission of gas to said chamber, and the said second tubing string connecting with the chamber through the pumping element to serve as a liquid eduction pipe for the liquid being raised from the Well.

2. In a device for raising liquid from a well, a tubing string including a standing valve adjacent one end thereof, a seat spaced from said valve, a second tubing string within and spaced from said iirst named string, a pumping element attached to said second string and having a shoulder cooperating with said seat to form a chamber for the accumulation of liquid,'said element having ports for the admission of gas to said chamber, ports for the exhaust of gas thereand opening said admission and exhaust ports,

and the said second tubing string connecting with the chamber through the pumping element to serve as a liquid eduction pipe for the liquid being raised from the well.

3. In a pumping device of the class described, a tubing string adapted to extend into a well, a valve adjacent one end thereof, a seat spaced from said valve; a second tubing string within said first named string; a pump element attached thereto and having a shoulder cooperating with said seat to form a closed chamber with said rst tubing string, a gas induction conduit in said element communicating with said chamber, a liquid eduction conduit in said element joining said chamber and said second named tubing string, a slide valve within said element adapted to open and close said induction conduit, and` means for positively operating said slide valve.

4. In a well pumping device, a tubing string extending within the well, a chamber at one end of the tubing string, a second tubing string within said first named tubing string, a gas induction conduit in communication with said rst named tubing string and said chamber, a liquid eduction conduit in communication with said second tubing string and said chamber, a gas exhaust conduit in communication with said cham- 'ber and the exterior of said first named tubing string, valve means to control the admission and exhaust of gas lthrough said induction and exhaust conduits comprising a cylinder in the second tubing string and a piston member suspended independently of said second tubing string. 4

5. Ina well pumping device, a tubing string extending within the well, a liquid accumulation chamber at one end of the tubing string and solely supported thereby, a second tubing string within and independently removable from said first named string, a gas induction conduit in communication with said second tubing string and said chamber, a liquid eduction conduit formed by the space between the first named tubing string and the exterior of the second string, said space being in communication With the chamber, `a gas exhaust conduit in communication with said chamber and the exterior of said first namedA tubing string, and valve positively operated from the well surface to control the admission and exhaust of gas through said conduits.

6. In a device for raising liquid from a well, a tubing string, a liquid accumulation chamber adjacent the lower end of -said tubing string, a

second tubing string within the first named tub- Ying string, a pump element on said second tubing string, means providing a seal between said element and said rst named tubing string to form a liquid accumulation chamber, said second named tubing string being movable relative to said first named string, a gas induction conduit in said element placing one of said tubing strings in communication with said chamber, a liquid eduction conduit in said element placing the other of said tubing strings in communication with said chamber, and valve means for controlling the admission of gas to said chamber positively operated from the well surface.

7. In a device of the class described for raising liquid from a well, a tubing string including a standing valve adjacent one end thereof, a second tubing string within the iirst named tubing string, a pumping element on said second named string, means providing a seal between said element and said second string to form a chamber for the accumulation of liquid, said element having gas inlet ports formed therein, ports in the element connecting the said second tubing string with the chamber for the eduction of liquid from the chamber, and a positively operated valve adapted to close and open said ports to control the admission of gas to said chamber.

8. In a device for raising liquid from a well, a tubing string including a standing valve adjacent one end thereof, a second tubing string within and spaced from said rst named string, a pumping element attached to said second string, means providing a seal between said pumping element and said rst string to form a chamber for the accumulation of liquid, said element having ports for the admission of gas to said chamber, ports for the exhaust of gas therefrom, ports connecting the said second tubing string with the chamber for the eduction of liquid from the chamber, and positively operated valve means for closing and opening said admission and exhaust ports.

9. In a pumping device of the class described, a tubing string adapted to extend into a well, a valve adjacent one end thereof, a second tubing string within said first named string, a pump element attached thereto, means providing a seal between said element and said iirst named string to form a chamber for the accumulation of liquid, a gas induction conduit in said element communicating with said chamber, a liquid eduction conduit in said element joining said chamber and said second named string, a valve within said element adapted to open and close said eduction conduit, and means for positively operating said valve.

10. In a device for -raising liquids from a well, a tubing string including a standingvalve adjacent one end thereof, a second tubing string within said first named string, a pumping. element on said second named string, means providing a seal between said element and said first named string forming a liquid accumulation chamber, said pumping element having a cylinder formed therein, a series of ports in said cylinder, a hollow sleeve valve within said cylinder provided with a series of ports adapted to cooperate with said cylinder ports alternately to place said chamber in communication with the interior and exterior of said iirst named tubing string for the admission of gas thereto and the exhaust of gas therefrom, respectively, means for positively operating said valve, and a valved conduit in said element placing said chamber in communication with said second tubing string for the eduction of liquid therefrom.

11. In a device for raising liquids from a well,

a tubing string extending Within the well provided with a standing valve adjacent one end thereof, a second tubing string within said first named string, a pump element in said second string, a seal between said pump element and said rst named string to form a liquid accumulation chamber, said element having a gas induction conduit therein by-passing said seal to place said chamber in communication with said first named string, a gas eduction conduit therein placing said chamber in communication with the exterior of said rst named conduit, a liquid eduction conduit therein placing said chamber in communication with said second tubing string, valve means located above said seal for controlling admission of gas to said chamber, valve means below said seal for controlling the exhaust of gas from said chamber, and means positively operated from the Well surface simultaneously to open one valve and close the other.

JAMES E. HOOVER.