US2064272A - Period control valve for plunger lift devices - Google Patents

Description

0. N. SCOTT Dec. 15, 1936.

PERIOD CONTROL VALVE FOR PLUNGER LIFT DEVICES Filed July 22, 1935 2 Sheets-Sheet l I I H 8 Z Clarence AZ 56055 INVENTOR Fig. 2

ATTORNEY C. N. SCOTT Dec. 15, 1936.

PERIOD CONTROL VALVE FOR PLUNGER LIFT DEV ICES F'ilegi July 22, 1935 2 Sheets-Sheet 2 n o r.' /.9Z

laz'enc'e 132'. 5:01?

INVENTOR BY ATTORNEY Patented Dec. 15, 1936 PERIOD CONTROL VALVE FOR PLUNGER LIFT DEVICES 9 Claims.

My invention relates to the operation of bored wells equipped with plunger lift apparatus in which liquid is raised by a plunger which travels from the pumping depth to the upper end of the well carrying with it a load of liquid to be discharged at the surface, said plunger being operated by pneumatic pressure, preferably gas. Devices of this kind are now well known in the art.

10 The oil and gas coming from such wells are obtained from strata of sand, porous rock, shale and similar formations in which the fluid is migratorily present. They are caused to flow from the producing formation into the well cavity or bore by removing them by natural or artificial means from said bore or cavity to the surface, thus reducing pressure in the well cavity and in the adjacent producing formation and enabling superior fluid pressure in the outlying producing formation to cause the fluid to flow towards and into the well cavity. This reduction of pressure is, as at present, continuously maintained While the well is in operation; which means that the flow of fluid from the producing formation into the well cavity is a fairly continuous and orderly flow, increasing in velocity in the said adjacent formation until maximum velocity is attained as the fluid emerges into the well cavity. This flow of fluid is through the pores, interstices and pockets which are in the producing formation.

' The fluid as it flows in the formation is generally accompanied with fine sand, lime, shale or other matter, largely in suspension and mobile 5 and so-called floating. They accumulate in and adhere to the pores, interstices and pockets of the formation through which they flow. As they accumulate they pack tightly due to the fact that the flow of the fluid is continuous in 40 movement and direction of movement and therefore holds them in a packed state. While the accumulation of this matter is slower in the zone immediately surrounding the well cavity, because of the higher velocity of the fluid flowing in it, the tendency to pack and remain packed is however greater in that zone and the obstruction thus offered to the flow of the fluid is much more eifective and serious, due to the small flow-areaway immediately surround- 50 ing the well cavity. This clogging of the producing formation naturally reduces the flow of fluid therethrough and adversely affects the production of liquid of the well.

Again: While the fluid is motionless in the 55 formation, or while the flow therethrough is orderly and without agitation, there is a process of dissociation in which the gas and liquid segregate into respective gas and liquid stratifications in the producing formation. As the fluid pressure becomes less in that zone adjacent the 5 well cavity, this stratiflcation of the gas and liquid becomes more pronounced still, with the result that the separate and independent flow of gas into the well cavity from the gas stratiflcations, without inducing or carrying along a 10 corresponding flow of liquid, is greater, but the flow of liquid into the well cavity is less, than though the liquid and gas were in intimate admixture and saturation throughout the entire thickness of the producing stratum. The more 15 open and porous the producing formation is, the more favorable it is for the flow of fluid through it, but the greater is the tendency to stratification of the gas and liquid and consequently the greater is the useless independent 20 flow of gas from the formation into the well cavity without inducing increased flow of liquid therewith. The more dissociation and separate stratification there is in the oil and gas in the adjacent formation, the more active and fluid 5 and live the gas is in its separate flow from the adjacent formation into the well cavity, but the more inert and lacking in fluidity the oil is, the less its induced flow will be from the adjacent formation into the well cavity. 36

Again: In such wells in which the plunger lift, as it is at present devised, is used for raising the liquid from the bottom to the top of the well, the liquid level in the well during the settled operation of the plunger lift remains continuously at about the elevation ofthe open lower end of the eduction tube (in which the plunger travels) with only slight cyclic variations in elevation above and below the open I lower end of the eduction tube; and gas pressure above the said liquid level during settled operation corresponds, with only slight cyclic variations, to the static pressure of the column of liquid in the eduction tube reaching from the open lower end of said tube to the surface of pressure is at its maximum and equals stabilized formation pressure, and maximum production when bottom-hole pressure is entirely removed.

It is apparent then, that when the maximum production of fluid is desired, bottom-hole pressure should be reduced to the minimum.

Again: With the plunger-lift device as at present constructed and in use, all the gas to raise the plunger and its load of liquid from the bottom to the top of the well must enter the eduction tube at its open lower end between said lower end opening and the surface of the liquid in the well cavity or casing and at the rate at which it is produced and flows from the adjacent formation into the well cavity, and not from any volume of storage gas, stored currently and cyclically, in the well casing. This method of introducing all the plunger propelling gas to the eduction tube at its extreme lower end, results in' conflict between the gas, entering the said tube, and the adjacent liquid and causes the upward movement of the plunger to vary in velocity and continuity of movement and prolongs the time required for said up stroke. Further, the plunger cushion stop, past which all the gas propelling the plunger must pass, obstructs the free passage of said gas.

I aim:

(A) To prevent the clogging of the said pores, interstices and pockets in the producing formation around and adjacent the well cavity and to keep them open and thereby maintain the production of the liquid (oil) from the well at the maximum, and;

(B) To prevent or reduce to the minimum, the dissociation of the gas and liquid and their consequent segregation into gas and liquid stratifications in the producing formation adjacent the well cavity, and;

(C) To restore and/or maintain intimate association and saturation and admixture of the gas and liquid in and throughout the thickness of the adjacent producing stratum, for the purpose of liVening-up and making more uniformly resilient and fluid, the liquid in said adjacent formation and minimize the useless separate flow of stratified gas into the well cavity, and;

(D) To remove from, or reduce in, the well cavity and the adjacent producing formation, to the fullest extent in percentage of total operating time and to the fullest degree in the amount of pressure reduction, the gaseous fluid pressure in the Well employed in lifting the plunger with its load of liquid to the surface. This is done in order to reduce bottom-hole pressure in the well and minimize pressure resistance to the flow of fluid into the well cavity from the adjacent and surrounding producing formation, and;

(E) To bring about the maximum output of oil from an oil well and the maximum flow of oil from the producing formation into the well cavity with efficient utilization of the minimum quantity of gas.

I have as contributing objects of my invention:

First: To effect violent and rapid automatically-actuated alternating reduction and reapplication of normal fluid pressure; or reduction of normal fluid pressure and reapplication of higher than normal fluid pressure, from and to the well cavity and the producing formation adjacent thereto. This is comparable to a breathing action of the fluid in said formation, because the volume of gaseous fluid is increased when fluid pressure is released, and is reduced when fluid pressure is restored or increased. This is due to the expansion and compression of the gas held in saturation or admixture throughout the fluid in the well cavity and adjacent formation, which makes the fluid live and resilient and compressible and expandible.

Second: To cause in the pressure reapplication period of the cycle, a return or reabsorption of a portion of the liquid from the well cavity back into the adjacent formation, accompanied by a thorough meandering or churning circulation of the same with gas and inert oil throughout the entire thickness of the said adjacent producing stratum. This is comparable to a process of continuous well washing.

Third: To effect interruptions and accelerations, disturbances and reversals or changes in direction of movement, and also agitation and meandering, of the flow of fluid in the producing formation adjacent the well cavity.

Fourth: To break-up any tendency to continuous and independent and separate stratified flow of the gas in the said adjacent formation.

Fifth: To force more intimate and more complete circulation and admixture of the liquid and gas in and between oil and gas stratifications and in and between the pores, interstices and pockets of the said formation.

Sixth: To cause frequent, fairly regular, and violent cyclic reductions or removals of pressure in and from the well cavity and adjacent formation, to reduce in or remove from them intermittently, pressure resistance to the flow of fluid into them from the surrounding formation.

Seventh: To cause violent, regularly-recurring pulsations in the flow of fluid in and from the adjacent formation.

Eighth: To reduce the time consumed in the upstroke of the plunger and so increase the number of strokes or plunger cycles per unit of time, to reduce the load carried by the plunger per stroke and consequently reduce the gas pressure required to propel the plunger.

The present invention is a modification of the inventions disclosed in my prior Patents Nos. 2,013,111 and 2,013,112, both issued September 3, 1935.

I have illustrated the invention as applied to a pumping well equipped with a plunger lift for raising the oil to the surface of the ground.

In the drawings herewith:-

Figure l is a central longitudinal section through the upper portion of a well installation embodying my invention.

Figure 2 is a similar section through the lower portion of the same well installation.

Figure 3 is a similar section through an intermediate portion of the same well installation and shows the well casing space partitioned into three compartments by two packers which is my preferred plan.

Figure 4 is a sectional detail of that preferred form of my period control valve used in that preferred well arrangement or plan which has two packers partitioning the well casing space into three compartments, an upper, a lower and an intermediate (gas storage).

Figure 5 is a sectional detail of the period control valve device and shows an alternative arrangement or adaptation in which one packer is used partitioning the casing space into two compartments only, a lower and an upper (gas storage). In this alternative arrangement the packing in the upper packer is installed in the inner stufiing box instead of in the outer to pack 01f the space between the eduction tube and body of the upper packer, to separate the control valve chamber and its passage from the upper compartment which latter in this alterna tive arrangement is connected and combined with the intermediate compartment, (the two forming the gas storage compartment).

Figure 6 is a central longitudinal section through the intermediate portion of the well installation and corresponds with Fig. 3 but shows that adaptation in which only one packer is used to partition the casing into only two compartments, a lower and an upper (gas storage).

Figure 7 is a fractional vertical cross section through a part of the lower end of the sleeve valve and shows a relief valve for relieving accumulated pressure in the closed chamber above the sleeve valve when the two compartment arrangement of the casing space is in use.

The well is shown as equipped with a well casing I having a casing head 2 thereon. Above said casing head is a flow head 3 secured to the casing head by the bolt and flange connection 4 and having a lateral fluid outlet port 5 leading to a separator or place of storage not shown.

The upper end of the flow head is formed into an eduction tube extension 5 in which I may connect a gate valve i. The upper end of the extension is closed by a bushing 8 having a cap 9 thereon and having a shock absorber it. There is an outlet port it at the upper end of the cap 9' normally closed by a valve l2.

A plunger latch and its automatic control mechanism is secured upon the flow head. The latch bolt I3 is extended into an opening in the side of the flow head and has a stem M projecting outwardly through the wall of the housing 21 to connect at IE to a bell crank lever pivoted upon a support at E5. The outer arm of the lever engages the rod H upon a piston l8 movable within a cylinder l9 and held resiliently downward by a spring as.

The cylinder has a port below the piston to which is secured a pipe 2i which connects at its outer end with a port 26 in the flow head. There is a check valve 22 in this line allowing passage of fluid from the head to the cylinder. I provide a bypass around the check valve 22 by way of a small pipe 23 in which is a hand adjusted choke valve 24.

The eduction tube 28, 28, 28" is secured at its upper end to a flanged supporting coupling 29 which is anchored in the coupling 4 in the casing and acts to close the space between the eduction tube and the casing at that point. Above the coupling 29 is a perforated nipple 313 connecting the eduction tube with the tube extension 6. The plunger is thus allowed to move past the fluid outlet formed by the perforations in the nipple.

The lower end of the eduction tube 28 is connected to a housing 3| for the stop plate 32 which is held resiliently upwards against a seat 33 by a spring 3t supported upon a washer 35 which rests upon the eduction tube 28", and strainer 31 through which the liquid and gas may enter the well. Or strainer 31 may be omitted and the lower end of tube 28 be left open.

At a point well above the level of the oil in the well I connect in the string of eduction tube 28 a control valve device. The control valve itself is preferably housed in an outer housing or barrel IEH. As shown in Figs. 4 and 5 I couple a special joint of tubing 28' in the string of eduction tube 28. This special joint 28 has provision made at 23A for the attachment of the housing Mi which is closed inwardly at its lower end at 28A and is also closed outwardly against casing i just above openings E90 by a packer or seal it: which together with a portion of the housing HH separates the lower casing compartment i2 3 from the gas storage (intermediate) casing compartment !25.

On the upper end of housing H)! above packer MI is a housing extension I02 consisting of a reducer attached to the top of HM and as many coupled tubular members (or joints) as are needed for the required volume of the said intermediate compartment. The said tubular members of extension m2 are spaced from the eduction tube 28, 28 to form passage ill which together with the open alternative packing space connects chamber lit with the upper compartment H3. They likewise are spaced from casing l to form between their perimeter and the inside surface of casing i, the said intermediate compartment I25.

Attached to the upper end of housing extension M32 is a packer body Ml} intended for use as a male or female packer. When the threecompartment arrangement or plan is in use the packing rings we are installed in the space between the packer body M!) and the casing l as shown in Fig. 4 and gland N50 is used and thus separates the upper and intermediate compartments. When the two-compartment arrangement or plan is in use the packing rings I50 are installed in the alternative packing space Ill] and the gland I62 is used as shown in Fig. 5 and the packer closes the space between the eduction tube 28' and the packer body it!) and separates chamber Hi and passageway Hi from the upper compartment I23 and connects together, through passageway NH, and combines the upper compartment I23 and the intermedi ate compartment I25 into one gas storage compartment of larger volume, as shown by Figs. 5 and 6.

Housing IQ! has a port or plurality of openings 598 located just below packer ll. They make communication, through the tubular body or housing Mil, between the lower compartment and the chamber Hi. Housing is! also has a port or plurality of openings 19! located just above packer IM. They make communication, through the tubular body of housing lfll, between the lower end of the gas storage compartment and the annular passage H2.

Within the chamber 'lH is an annular or sleeve valve [8i shown in Figs. 4 and 5 in normal closed position corresponding with the pressure-reapplication period of the cycle. It consists preferably of three consolidated members; a lower annular one of such vertical length as to close openings I90 with proper overlap; and an upper annular one having its lower edge (in the normal closed position of the valve as shown) above the uppermost oi the openings IN and oii such length as to prevent harmful leakage of gas past it; and a concentric tubular body connecting the two said annular members and forming an annular passage H2 connecting openings l9i with the uppermost of the openings I90 and partitioning said port H2 from chamber IH.

Above the openings WI and below the upper end of housing IOI are openings or a port I92 making communication between the gas storage compartment and the upper end of chamber I I I. They are closed from chamber III by valve I8I in all positions of same except when it is moved to a sub-normal position with spring I22 compressed by strong pressure admitted to the upper compartment (when the three-compartment arrangement or plan is in use) and acting on the annular area of valve I8! which moves it downward and uncovers openings I92 and admits said strong pressure from the upper compartment into the intermediate compartment from which it escapes, through those openings I9I which are still uncovered and valve port H2 and the uppermost openings I90, into the lower compartment above the liquid in same; as when putting the well back to pumping after a shutdown.

Tubing section 28 has a port or openings 2I9 through its tubular body registering approximately with the port or openings I90 in the housing IOI and making communication between chamber III and the interior of eduction tube 28'. When the sleeve valve MI is in full open position it uncovers all of the ports or openings I90 and Eli! and thus opens communication between the lower compartment and the interior of the eduction tube 28, 28', through chamber III under the lower edge of the open valve I8I.

At the lower end of chamber III are ports or openings 220 through the tubular body of the eduction tube joint 23 and making communication between the chamber II I and the interior of the eduction tube 28' below valve I8I in all of its operating positions.

Above the sleeve valve I8! is a spring I2I which offers resistance to the opening of said sleeve valve and acts to close it against reduced pressure in the lower compartment and in eduction tube 28, 28 and in the lower end of chamber III under sleeve valve I8I. Under the sleeve valve I 8I, in the lower end of chamber II I, is a spring I22 of materially greater resistance than spring I2I. This spring I22 fixes the normal closed position of valve I8I when substantially uncompressed. I may provide a relief valve in a passage through the lower end of valve I8I from passage III when the valve is in raised position.

Tubing section 28' has an exterior cylindrical surface 8I, extending from edge 22I to below the lower end of valve I8I in its normal closed position, which has sliding contact with its companion surface, the inside cylindrical surface of the valve I8I. The lower edge of the valve in its full open position is intended to uncover the uppermost openings 2I9 and the edge 2 is placed at such distance above the said openings as to provide overlap sufiicient to prevent harmful leakage of gas.

The normal closed position of valve I8I is shown in Figs. 4 and 5, having closed communication through openings I90 and 2| 9 between the lower compartment I24 and the eduction tube 28, 28 and having opened communication, through openings I9I and valve port II 2 and uppermost openings I90, between the gas storage compartment I25 and the lower compartment I 24.

I have shown packer I4I fitted with pressure cups I42 held in by gland I43. As in the case of packer I40, any preferred form oi] packer or seal may be used.

My invention includes the placing of superior fluid pressure upon the adjacent formation and then releasing such pressure. This may be alternated repeatedly. When a sufiicient flow of gas from the producing formation results, operation thereafter will be automatically as follows:

Valve I8I as shown in Figs. 4 and 5 has just closed openings I90 and 2!!! from chamber III and thus interrupted communication between the lower compartment I24 and the interior of the eduction tube 28, 28', concluding the pressure-reducing period and initiating the pressure-reapplication period of the cycle. It has at the same time uncovered the uppermost openings I90 to valve port II2 making communication, through openings I9I and port H2 and uppermost openings I90, between the gas storage compartment (which is filled with gas at maximum built-up pressure) and the lower compartment (which has minimum gaseous pressure and the {desired maximum built-up level of liquid in it).

Static pressure of the built-up column of liquid in the lower compartment now approaches fluid pressure in the formation. Maximum stored up gas pressure from the gas storage compartment enters the lower compartment (through I9I, H2 and uppermost I90) on top of the built-up liquid level in same and adds its equalized pressure of gas to the static pressure of the built-up column of liquid, making the resulting increased bottom-hole pressure largely predominate over normal formation pressure. This causes a rapid depression of the level of the liquid in the lower compartment with reabsorption and reversed flow of liquid back into the adjacent formation from the well cavity. Gas continues to flow into the lower compartment from the well cavity and adjacent formation and (lower openings I90 and openings 2I9 being closed) accumulates and builds up to the desired maximum gas pressure in both the gas storage and lower compartments and continues to depress the liquid level in the lower compartment still further. Finally the depressed liquid level reaches the desired low level, corre sponding with the elevation of the open. lower end of the eduction tube, and uncovers same (or the upper perforations of the strainer 31 if used) and admits gas from above the depressed liquid level in the lower compartment into the eduction tube 28", dumping and displacing the liquid in same underneath the plunger 54 which is in its lowest position with valve 51 closed by the engagement of stem 58 with stop plate 32 (sometimes called cushion stop). Dumping the liquid from the lower portion 28 of the eduction tube and displacing it with gas lightens the column of liquid in the eduction tube so that gas pressure above the depressed liquid level in the lower compartment predominates over the lightened column of liquid in the eduction tube and moves the plunger, with its load of liquid above it, on the initial stage of its up-stroke; the propelling gas entering the open lower end of the eduction tube. As the plunger rises and passes openings or ports 220 fluid pressure from above and below the plunger enters the lower end of chamber I I I through these ports or openings and acting under sleeve valve I8I moves it up until its lower edge uncovers lowermost openings I90 and 2I9, exposing the lower annular area of the valve to full gas pressure from the lower compartment I24 which moves the valve up into full open position and admits full pressure gas from the lower compartment into .thatgas pressure in the lower compartment may the eduction tube under the rising-plungento complete its up-stroke. As'the sleeve valve .18! moves up from its normal closed position to uncover thelowermost openings. I90 and 2M, it closes the uppermost openings i99 closing off the gas storage compartment from the lower compartment and thus trapping thestored gas under maximum built-up gas pressure in the gas storage compartment while built-rup gas pre sure is being released, in the pressure-reducing period, from the lower compartment above the the top of the tubing, the load of liquid will have depressed liquid level in same.

The fluid pressure in the flow head, as the plunger approaches the upper end ofthe tube, will be sufficient to force the piston it in the cylinder 19 upwardly so as to permit the 'latch I3 to be moved to plunger engaging position by the spring behind it. When the plunger reaches pelling gas will, then escape through the o-penings in the nipple 3i! and flow pipe 5 from the eduction tube 28, terminating the pressure-reapplication period of the cycle and beginning the pressure-reducing period.

As the fluid pressure in the flow head is relieved, the fluid below the piston-l3 will gradually exhaust through the choke valve 24 and bypass 23 to the flow head and allowthe piston M3 to bemovedto position to release the latch l 3 and allow the plunger to drop. 7 By the proper adjustment of the choke valve 24, this release-of the plunger may be timed to suit conditions in the well so that the plunger will not reach'bottom until the proper level of the plunger loading liquid in the lower portion of the eduction tube 28 has been reached by the incoming fluid.

Gas will continue to escape, through the eduction tube, from the lower compartment I2 1 I through openings I90 and 2l9 and-chamber Hi, i

and quickly reduce the pressure of the gas in the lower compartment above the depressed liquid level in same.

This reduction in gas pressure above the reduced (depressed) column of f liquid in the lower compartment, causes a corresponding reduction in bottom-hole pressure in the well cavity and the adjacent formation and brings about a rush of fluid from the adjacent and surrounding formation into thewell cavity and lower compartment; the liquid content of v the entering fluid building up liquid level in the well cavity and lower compartment and the gas content of the entering fluid passing on out from the lower compartment through openings I90 and 2l9 and chamber H i and eduction tube is 28' and 28 -and.flow pipe 5-or-other surface loading, when spring 12! moves valve l8! down into closed position against reduced gas pressure under same; and again terminates the pressure- -reducing period and again initiates the pressure- -reapplication period.

The operations by periods and cycles are continuously repeated. It should be understood be built-up by gas entering the well currently from the producingformation; or by'gas and/or air from a surface source, or by both.

It willbe noted that valve ltil is remotely actuated into opening (to admit built-up gas pressure to the eduction tube 23', 28 under the rising plunger, to continue and complete its upstroke and release gas pressure from the well cavity). by the predetermined low level of the liquid in the lower compartment, as fixed by the elevation of the .open lower end of the eduction tube; that it is directly actuated and moved into opening position by fluid pressure in the eductiontube, immediately above and below therising plunger as it passes the said valve in the initial stage of its up-stroke'; and that it is actually opened by gas pressure in the lower compartment admitted to the underside of said valve after it has been actuated into opening-- position by fluid pressure from the eduction tube.

It will also be noted that this valve i8! performs several functions, namely:

First: That of a gas supply valve opening to:

admit gas to liftthe plunger and its load of liquid throughout the major portion of its upstroke, and;

' Second: That of a gas releasing valve, remain- -ing open and releasing, if so desired, substantially all the gas which was shut-in, in the lower compartment and well cavity and adjacent formation, during the preceding pressure-,reapplication period, and;

Third: That of a minimum-pressure regulat ing valve, closing and preventing further escape of gas from the lower compartment to the eduction tube and flow lines when gas pressure has .beenreduced in said lower compartment above the liquid in same to a predetermined minimum,

as fixed by the force of spring IZI actingto close the valve against the said minimum gas pressureactingron the underside area of the valve to resist its closing, and;

, Fourth: That of a gas-admission valve, and

gas discharging valve, serving the gas storage compartment; opening to discharge gas stored in said compartment under maximum built-up pressure and admit same tothe lower compartment above the built-up column of liquid in it; remaining open to again charge the gas storage compartment with built-up gas pressure from above the depressed liquid level in the lower compartment; then closing to store or hold the builtup gas pressure in the said gas storage com-1 partment,.. while gas pressure is being released from thev lower compartment in the pressurereducing period.

Fifth: That of a hand controlled pressure-admitting and pressure releasing valve for admite ting and releasing pneumatic pressure from a surface supply to the lower compartment above the dead liquid in same, as when putting the well back to pumping after a shutdown.

It will be further noted, that a characteristic and requisite feature of this valveit! is: that while gas pressure in the lower compartment in the pressure-reducingperiod, only slightly above the predetermined minimum, must prevent the said valve from entirely closing, gas pressure in said compartment throughout the pressurereapplication period much greater than the said minimum pressure in the pressure-reducing period must not'cause the valve to reopen. In

other words; the valve which must remain open or partly open throughout the pressure reducing period, while gas pressure in the lower compartment above the liquid is changing from maximiun to minimum must not reopen in the pressure-reapplication period while the pressure is changing back from minimum to maximum.

What I claim as new is:

1. In a plunger lift device, a well casing, an eduction tube spaced therein, packers between said tube and easing dividing the space between said tube and casing into upper, intermediate and lower compartments, a valve normally closing openings from said lower compartment to said tube but permitting passage of fluid between said lower and said intermediate compartments, a plunger in said tube freely movable from the lower to the upper end thereof, said valve being movable to open communication from said lower compartment through said openings to said tube under said plunger and close the passage of fluid between said lower and said intermediate compartments in response to an adequate increase of fluid pressure in said tube, said upper chamber acting as a storage chamber adapted to be placed in communication with said intermediate chamber in response to a preponderance of pressure in said upper chamber.

2. In a plunger lift device, a well casing, an eduction tube spaced therein, packers between said tube and casing dividing the space between said tube and casing into upper, intermediate and lower compartments, a valve normally closing openings from said lower compartment to said tube but permitting passage of fluid between said lower and said intermediate compartments, a plunger in said tube freely movable from the lower to the upper end thereof, said valve being movable to open communication from said lower compartment through said openings to said tube under said plunger and close the passage of fluid between said lower and said intermediate compartments in response to an increase of fluid pressure in said tube, and means to move said valve to close said openings and open the passage of pressure fluid between said intermediate and said lower compartments when the reduced gas pressure in said lower compartment reaches a predetermined minimum value and the liquid level in said lower compartment has built-up to the desired elevation, said upper compartment being connected with said intermediate compartment when a predetermined preponderance of pressure in said upper compartment is reached.

3. In a plunger lift device, a well casing, an eduction tube within said casing and spaced therefrom, upper, lower and intermediate compartments between said casing and tube, a plunger operated in said tube by fluid pressure, a valve normally closing the passage of fluid from the upper end of said lower compartment to said tube but opening a passage between said lower and intermediate compartments, said valve being actuated by an increase in fluid pressure in said tube to open and allow passage of gaseous pressure fluid from said lower compartment to said tube and to trap gaseous pressure fluid in said intermediate compartment, and means to return said valve to normal position when the pressure of gaseous fluid in said lower compartment has exhausted to a predetermined amount, said upper compartment being connected with said intermediate compartment when a predetermined preponderance of pressure "in said upper compartment is reached.

4. In a plunger lift device, a well casing, an eduction tube spaced therein, a packer between said tube and casing dividing the space between;

plunger and close the passage of fluid between:

said lower and said upper compartments in response to an increase of fluid pressure in said tube.

5. In a plunger lift device, a well casing, an eduction tube spaced therein, a packer between said tube and easing dividing the space between said tube and easing into upper and lower compartments, a valve normally closing openings from said lower compartment to said tube but permitting passage of fluid between said lower. and said upper compartments, a plunger in said tube freely movable from the lower to the upper end thereof, said valve being movable to open communication from said lower compartment through said openings to said tube under said plunger and close the passage of fluid between said lower and said upper compartments in response to an increase of fluid pressure in said tube, and means to move said valve to close said openings and open the passage of pressure;

fluid between said upper and said lower com.- partments when the reduced gas pressure in said lower compartment reaches a predetermined minimum value and the liquid level in said lower compartment has built-up to the desired eleva-- tion.

6. In a plunger lift device, a well casing, an eduction tube within said casing and spaced therefrom, upper and lower compartments between said casing and tube, a plunger operated partment, and means to return said valve tonormal position when the pressure of gaseous fluid in said lower compartment has exhausted to a predetermined amount.

7. In a plunger lift device, an eduction tube adapted to be inserted into a well, a'plunger movable in said tube from the lower to the upper end thereof, there being openings in said tube at a point spaced from the lower end thereof, a valve normally closing said openings, said valve opening to allow passage of pressure gas from the lower end of the well to said tube in response to an increase of pressure of fluid in said tube, means controlled by said valve when in open position to trap built-up pressure gas above said valve outside said tube, and means to close said valve when: the gas pressure in said lower well end has decreased to a predetermined value and release the trapped pressure gas to the said lower end of the well and consecutively to admit building-up pressure gas from said lower well end into said pressure-gas trap.

8. In a plunger lift device, a well casing, an eduction tube therein, a pneumatically operated plunger in said tube, perforations in said tube intermediate its ends, a housing closed against, said tube below said openings, there being openings in said housing opposite the perforations in said tube, a packer on said housing engaging said casing to provide a gas storage chamber, a valve on said tube and inside said housing normally closing said perforations and providing a passage between said gas: storage chamber and the casing space above the liquid in the well for gaseous fluid, said valve operating in response fluid pressure to open the entrance of gaseous pressure fluid to said tube from said casing space and to trap gaseous fluid in said gas storage chamber, and a spring to close said valve and open the passage from said chamber to the said casing space above the liquid in the well when the pressure of gaseous fluid in said casing space above the liquid is diminished to a predetermined value and the liquid level in the said space has built-up to the desired elevation.

9. In a plunger lift device a well casing, an eduction tube therein, a pneumatically operated plunger in said tube, perforations in said tube intermediate its ends, a housing closed against said tube below said openings, there being openings in said housing opposite the perforations in said tube, packers on said housing engaging said casing to provide a gas storage chamber, a valve on said tube and inside said housing. normally closing said perforations and providing a passage between said gas storage chamber and the casing space above the liquid in the well for gaseous fluid, said valve operating in response to fluid pressure to open the entrance of gaseous pressure fluid to said tube from said casing space and to trap gaseous fluid in said gas storage chamber, and a spring to close said valve and open the passage from and to said chamber when the pressure of gaseous fluid in said casing space above the liquid is diminished to a predetermined value and the liquid level in. said space has built-up to the desired elevation, said valve being movable downwardly below normal position to provide a passage through said housing for superior pressure fluid admitted above said packers to the space below said packers.

CLARENCE N. SCOTT.

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