US2489665A

US2489665A - Pneumatic feed for gas lifts

Info

Publication number: US2489665A
Application number: US585473A
Authority: US
Inventors: Charles M O'leary
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-03-29
Filing date: 1945-03-29
Publication date: 1949-11-29
Anticipated expiration: 1966-11-29

Description

Nov. 29, 1949 c. M. O'LEARY 2,489,665

PNEUMATIG FEED FOR GAS LIFT Filed March 29,` 1945 2 Sheets-Sheet 1 Nov. 29, 1949 c. M. OLEARY 2,489,665

PNEUMATIC FEED FOR GAS LIFT Filed March 29, 1945 2 sheets-sheet 2 Gas Suiv/:ly Pressen-c )Dr-essere L51 7,5 n ,Blow aff/20e opens f f za closes Patented Nov. 29, 1949 UNITED STATS --PTENT l"Oll'il-Cll PNEUMATC FEED FOR GAS LIFTS Charles M. DLeary, Detroit, Mich.. f

Application Mal'ch '29, 1945Selial N0. 585,473

12 clams.' (ci. 10a-'2321 l v The lpresent invention .relates to means for flowing loil wells by gas under ,pressure and resides in Aan improved form of bottom hole intermitter particularly adapted :for use on large production deep wells. t

Ordinary gas lift installations are not particularly effective on large production deep wells, due to the lfact that the gas pressure required at the bottom of the well to lift the column of oil materially retards inilow yof oil from the formation. In addition, the natural flow rate of wells varies constantly, with the resul/t that it is difficult to determine or maintain the optimum gas-oil ratio for owing the well. LAccordingly, attempts have been made to relieve the bottom of the well from the pressure resulting trom the long l'column of oil and gas in lthe outflow tubing and to maintain a constant rate of oil iiow by installing iiow chambers in the bottom di the well which are equipped with --check valves past which oil may flow by gravity to lill the chamber. These chambers are then intermittently blown by gas pressure to force the `oil up into the oil outflow-tubing without applying the pressure .in the tubing to the formation. In certain of these constructions control of the blowoff and lling periods has been achieved by periodically varying the gas pressure supplied to the well at the ground surface. This expedient, however, is objectionable because of the long time required to bui'ld up the ,pressure of the llarge volume of gas 'in the tubing of a deep well. In addition, 'these prior expedients .have operated to blowr each slug of oil entirely from the wel-l,

with the result that excessive quantities of gas trolled vaive mechanisms have proved Auz'tsat'isfactory for several reasons. In 'the 'st place.,

the f ioats are subject 'to `forces resulting 'from the how or surging of 'gas and oil independent of the oil level. Secondly, the lfloat mechanism is yquickly clogged by wax and foreign matterin the oil; and, nally, if the lioa't `and float mecha' ainism are made suciently large and heavyjto a.

minimize the nrst two dnieulties, Athey require too much vspace at the bottom of the well and, therefore, cannot be installed or removed without removing `all of the oil outflow tubing. Accordingly, it is the general object of the present invention to provide a bottom hole in# termitt'er 'which will periodically blow the oil from the iling chamber'into'the oil tubing, in which it may be lifted by an auxiliary gas 'supply during the reiilling period, and 'in which the cycle oi operation is controlled by the gas sup' plied'under relatively constant pressure to the bottom of the well through a macaroni or gas tubing.

','Another object of the invention is to provide a mechanism of the type mentioned, in which the relative duration of the filling and blowen periods' may be readily adjusted to accommodate 'the nat' ural flow conditions of the well by adjusting the pressure 'o'f the gas supplied.

" Another 'object of the invention is to provide a mechanism of the type 'mentioned which incorporates no mechanism or moving 'parts in con-` tact with the oil except the conventional bali check valves associated with the 'ow chamber and which, thereiorecanno`t Vget out of order by reason of accumulations of wax vor foreign materials such as are (present in the liowing oil.y

'Another object of the present invention "1s to provide a mechanism of the type mentioned in which all of the operating and control valves are oi the Apoppet or ball check type in which a positive gas pressure operates to hold them in their closed positions and in which all of the valve operations are vcontrolled by gas pressure.

Another object o the invention is to provide a mechanism in which all relatively sliding parts are 'sealed against Contact with gas supplied to the unit and the oil in the well and tubing. *Y Another object of the invention is to provide a mechanism of the type mentioned, in which the frequency of the cycle of operation may be ati-'- jps'ted to a limited extent by changing the gas sjiipply pressure, and in which the frequency may' be' adjusted over a 'wide range to suit conditions existing in vany given well by very simple ad` jjustments. jjAnother object ofthe vinvention is to provide a mechanism of the type mentioned, all portions of which, except the flow 'chamber itself, 'may andere be Xed to the lower end of the macaroni or gas supply tubing and inserted into or Withdrawn from the oil outflow tubing Without disturbing the latter.

Another object of the present invention is to provide an improved form of valve mechanism for producing a uctuating gas pressure from a constant pressure source for use in operating a pressure responsive device.

Other objects, which include the provision of an intermitter of the type mentioned which is extremely rugged, compact, and simple in construction, will become apparent from the following speciiication, the accompanying drawings, and the appended claims. l

In the drawings,

Figures l and 2 are, respectively, sectional viewsf.-

taken through the upper and lower portions or the preferred embodiment of the inventions# Figures 41 5 and 6 are pressurekldiagrams illusf trating the principle of operation of the mecha:

msm.

yReferring to the drawings, anldparticularly Fig-f usilggand 3 tnereoith inprveaintermitter mechanism comprises a, generally cylindrical valve block I, to the' lower 'end f which is xed an elongated cylindrical shell'2"forming the walls of a now chamber which Vmay be of any desired length and which is closed at its lower end by means of a plug 3. Valve block 2v also `carries a centrallyl located oil now tube '4 which projects downwardly into the low chamber and carries at'its lower end a housing Banda ball check valve 6 which operates to permit free flow of oil uph-r Wardly through theV tube, but prevents reverse flow. The plug 3 is likewise provided with a down` Wardly projecting iniiow oil tubing 'I which com" municates with a port 8 in the plug 3. The port 8"is controlled by means v4of aballcheck valvev S'positioned with reference to the port 8 by means o'f a cage I8. This ball check valve 'permits free inow of oil through tubing Ito 'the interior of the chamber 2 but prevents reverse flow. The inflow tubing 'l may be of anyde'sired length, but it"will be' appreciated that tle 'entire chamber 2 must be located below the natural oil level in the well in order to permit the gravity ow of oil into the chamber past the'y checkvalve 9. *'To the upper end of the valve block I is secured asimilar cylindrical casing II, the upper end of which is threaded, or otherwise suitably secured, to the lower end of the oil outflow tubing I2.

The remainder of the mechanism, which includes the control valves for intermittently blowing the 'chamber 2, is xed to the macaroni or gas supply tubing I3 and may be inserted or removed without 'disturbing the oil tubing I2 and the por' tions of the mechanism carried thereby. This control valve mechanism is mounted in an elongated cylindrical chamber I4 which is threaded or otherwise fixed at its upper end to the lower end of the gas tubing I3, andy which is closed at itsl lower end by means ofla conically tapered block I5 that is adapted to seatwithin, and make sealing engagement withLarcorrespondingly conically tapered recess I6 formed in the upper end of the valve block I. The b1ockI5 is provided with a'central bore I1 which is adapted to communicate with a passageway I8 in the Lvalve blocl-ry I, and the latter passageway communicates with the interior of the chamber 2. The valve block I is provided with an opening I9 in its lower face in communication with the interior of the tube 4.

which in turn communicates at its upper end with a plurality of passageways 29 which connect to the space between the housings II and I4. The conical recess I6 in the valve block I is provided with an annular groove 2| which communicates with a port 22 in the valve block which opens to the well space outside the oil outflow tubing, the housing II, and the chamber 2 at a point above the chamber 2. The channel 2! likewise communicates with passageway 23 in the block I5 which leads to the space within the housing I4.

The housing I4 is made in three sections, 24, 25, and 26. Sections 24 and 25 are connected by means 0f ablock 21, and sections 25 and 26 are connected by means of a block 28. Block 21 is fixed to an upwardly projecting cylindrical housling 29 within the housing section 24, leaving a space 30 between the walls of the housings 24 and 29. `A .cylindrical housing 3I is xed in sealing relation to and between the blocks 21 and 28, withinthe'housing section 25, and the walls of the housings 3I.and 25 are spaced apart to provide a passageway 32. The passageways or spaces 38 anrdc32 are connected through a plurality of openings 33 in the block2I, as best shown in Figure 3,-and the space 3D is inunrestricted 'coni-A mun'icati'n at its upper end with the interior of theigassupply tubing I3. Block 28 is provided with a side Vport 34 connecting the space 32v to. a valve chamber 35 having a gas blowof `valve' 36 controlling a port 31, whichris connected by a plurality of passageways. 38, through the block- 28, to the space within a eXible bellows 39, the upper end of which is i'ixed to the lower face-ofthe block 28. The bellows 39. carries at `its lower end'a plunger in the form of a'valve element indicated generallyat 4G, which is made up of a hol-` low stem 4I and a poppet type head 42, adaptedto co-operate with a valve seat 43 at the upper end of the passageway-I1 in block I5. The crosssectional area ofthe valve seat 43 is greater than the -cross-sectional area of the bellows 39, and the opening-44 in the tubular valve stern 4I isl more restricted to the passageways 38 and 23,

454 with the result that any iiow of gas through the' passageway 44 tends to elongate the bellows 33 andseat the valve 40.` `The normal length of the' bellows 39 is such as to hold the valve 48 in spaced, relation to the seat 43 when no gas is flowing'l through passageway 44, and the effective area of valve 42fis greaterthan that of bellows 39. `As a` result of the mechanism so far described, it will be apparent that normally the blowoff valve 36 closes the port 37 in block 2 in responseT to the pressure of the supply gas, thus shutting oiwow of gas through the tubular valve 4i) and causing that valve to unseat, as illustrated in the drawings. Under these conditions, the upper end v of the chamber 2 is connected to the low pressure space within'thewell by means of passageways I 8, 23, and 22, andnov gas under pressureV is vsupplied to thechamber. l When .the check valve 33 is* forced off its seat against the gas supply pressure which normally maintains it ina seated condition, gas under Apres-r sure will ow from the gas supply tubing through space 30, passageway 33, space 32, passageway 34,- port. 3l, passageway 38, bellows 39, valve 49, and passageways I1 and I8 tothe upper end of the ow chamberY 2, and therebyseat the ball lcheck valveA 9 and forcing ,any Aoilwithin vthe chamber upwardly past the check valve 6 through the tub`-,k ing 4, passageways I9 and 28 tothe space between., the housingsgl Land I4..` and `thence to the oil out-1 flow space between the oil tubing I2 and the gas ausgabe.

tubing I3. Since, during these conditions, the space within the housing section 26 is at a lower l pressure than the pressure in passageway I1 and bellows 39, and the area of valve head 42 is slightly greater than that of the bellows 39, the pressure within the passageway I1 tends to unseat the valve 49. However, a small pressure drop of the gas passing through the restricted passageway 44 in the valve overcomes that tendency and maintains the valve in a seated condition so long as the check valve 36 is unseated. As soon as the check valve 36 is seated, flow through valve `I stops, and the pressure within passageway I1, which is the pressure within the upper end of the chamber 2, unseats the valve 49. In this connection it will be noted that the pressure within the upper end of the cham-ber 2, when valve 42 tubing. It will be observed that valves 36 and 42, in combination, operate as a three-way Valve to connect the chamber 2 either to exhaust or to the full supply gas pressure. The particular construction and form of valve disclosed is peculiarly suited to an oil well insert mechanism because of its in-line arrangement, and has no relatively moving parts, except the poppet type valves and seats exposed to the gas or oil.

The oil which flows upwardly through the outilow tubing may be lifted 'by gas supplied thereto in any desired manner, such as by the small opening 45 in the lower end of the gas tubing i3. It will be understood that any other means for supplying gas to the oil column, including `gas supply valves responsive to the pressure in the oil tubing, may be employed in accordance with conventional practice.

The ow chamber 2 is entirely immersed in the oil normally standing in the well to any desired depth except that the external pressure on inlet f 8 should not exceed the gas supply pressure inl tubing I3, since otherwise the oil would simply flow continuously through chamber 2. This is undesirable because there would then be no way of maintaining the oil flow raterconstant, with the result that it would be difficult to maintainv chamber 2 during the filling period will remain constant regardless of the depth oi immersion of the chamber in the oil since it is a function cf the size of the oil inlet port 8 and the distance (and therefore the pressure difference) between the port 8 and port 22.

Valve 36 is unseated by means of a stem 46 fixed to a plunger member 41, which is secured to and seals the lower end of an expansible bellows 48. The upper end of the bellows 48 is xed and sealed with respect to the lower surface of block 21 in communication with a passageway 49 through the block. A second expansible bellows 50 surrounds the stem 46 and is secured in sealing relation at its ends to the vplunger 41 and the upper surface of block 28. The effective crosssectional area of the bellows 59 is approximately equal to the effective cross-sectional area of the ,port 31, and the effective cross-sectional area of the bellows 48 is slightly greater than that of the bellows 50. As a result of this arrangement, ap-

plication` of pressure to the interior of bellows 48 in an amount less than that of the gas supply pressure acting on the bottom of the blowofI valve 36 will open that Valve, and the blowoff valve is balanced against the influence of pressure within the bellows 59 and port 31. The amount of pressure in belows 48 required to open valvev 36 depends upon the ratio of the area of the bellows 4B to the port 31, as hereinafter pointed out in greater detail. bellows 59 the pressure in port 31 would rise on opening of the blowoif valve 36, and the resulting increase would tend to move the plunger 41 upwardly and thereby tend to close blowoif valve 36. This would throttle down the pressure in port 31. The bellows prevents this throttling action and, therefore, insures application of the full gas supply pressure for 4blowol purposes.

Means are provided for periodically increasing and decreasing the pressure within the bellows 48 at a predetermined frequency in order to alternately fill the chamber 2 and eifect a blowoif of the oil in the lled chamber. This means comprises the aforementioned passageway 49 in block 21, a lateral bleed passageway 5I connecting passageway 49 to the oil space between housings II and I4 and an intermitter valve 52 for controlling the admission of gas under pressure to the passageway 49. The intermitter valve 52 is operated by an intermitter mechanism, the major portion of which is located within a cylindrical housing 53 xed in sealed relation to the upper end of block 21 and provided at its upper end with a small inlet bleed port 54 communicating with the supply gas under pressure in the gas tubing i3. The cross-sectional area of the bleed port 54 must be smaller than the cross-sectional area of the previously mentioned bleed port 5 l as pointed out hereinafter in greater detail. v Housing 53 is provided intermediate its ends with a block 55, to the upper surface of which is fixed a cylindrical housing 56 containing a plunger 51, which is normally urged downwardly by means of a spring 58. A stem 59 connects the plunger 51 to a plunger 69, which is fixed to the intermitter valve 52, with the result that the spring 58 normally acts to hold the intermitter valve in closed position. A flexible bellows 6I is fixed in sealed relation at its ends to the underside of block and to the plunger 60, with the result that the spring 58, plunger 51, and stem 59 are entirely sealed against contact with the gas in the housing 53. The block 55 is provided with a plurality of openings 62 providing an unrestricted communication within the housing 53, between the space above the block 55 on the outside of housing 56 and the space below the block 55 on the outside of the bellows 6|.

The operation of the intermitter valve mechanism is as follows: Gas at supply pressure in tubing i3 enters the bleed port 54 and gradually builds up the pressure within housing 53. This pressure, acting on the underside of plunger 68, tends to lift intermitter valve 52 off its seat, and that tendency is resisted by means of spring `59. The strength of the spring is so chosen with respect to the effective cross-sectional area of the plunger 60 and bellows 6I that the intermitter valve 52 is not opened until the pressure within the housing 53 reaches a pressure slightly below that of the gas supplied in tubing I3. When that pressure is reached valve 52 opens, thus per mitting a flow of the gas within the housing 53 throughthe passageway 49 of the interior bellows 48.

In the absence of thel It is desirable, although not necessary. t0-

aree/,cos

7"* reducey 'the pressure drop incident 't6-th' filli-"rlgfl bellows f'litoav minimumand, accordingly, there is illustrated a cylindrical'plug 63 fni'ed'to th plunger 41 substantially filling-'the bellows48 to'" reduce 'its volumetric capacity. Once the valvel- 52f`is opened the eective area of th'e plunger v(ill` is increased by the area of the valve 52 and, consequently, the valve 52 will remain o'pe'until theV pressure within the housing 53 drops to a valuer` belowlthe pressureat which valve 52 was opened'. It is desirable to keep the dilerence between'thei pressures at which valve 52 opens and closes toa" small value, in the order of 25 to 50 pounds per square inch.

As soon as the valve 52 is opened the -pressure within housing 53, passageway 49, and bellowsr48^ will begin to drop, by reason of the outflow of Ygas Y through the bleed port. I.4 Since this' bleed portV has a vlarger effective area than the bleed port 54, the gas will flow outwardly through port 5| faster than it enters port 54, and result in a graduali reduction in the pressure within the housing 53 and ythe bellows 48. After the pressure Adrops to' the point at which valve 52 closes, the pressure in bellows 48 drops rapidly7 to the pressure existing in the space between the housings l I and I4 (the pressure head at the bottom of the oil outflow tubing), and at the same time the pressure within the housing 53 begins to build up by reason of the flow through port 54.' It will be apparent that by adjusting the sizes of the ports 54 and 5l relative to the volume ofthe gas space within the housing 53 and the bellows 48, the frequency with which the valve 52 opens and closes may be readily adjusted.

. Thus, if the size of opening 54 is increased while all remaining features of the design remain un'- changed, the period of time required to build up' pressure in housing 53 will be reduced, and consequently the period of time during which the valve 52 is closed will be correspondingly reduced; and vice versa. By the same token any increase in the size of passageway 5I, all other features of the design remaining the same, will shorten the period during which valve 52 is open; and vice versa.

The frequency of each complete cycle of operation of the valve 52 for any given pressure in the gas supply tubing I3 is Xed by the strength of spring 58, the relative effective areas iof v the plunger 66 and the valve 52, the sizes of bleed,k ports 54 and 5I, and the volumetric capacity of the housing 53 and the bellows e8. However, for'. any en frequency for the complete cycle of` `operation vthe relative proportionsof the fillingv and blowo portions ofthe completecycle may bevaried by varying the relative cross-sectional areas of the bellows 48 'and 5D. In, additionfthe relative proportions of the complete cycle devoted to the filling and blowoi periods may also be materially varied for any given construction by. slight variations in the pressure supplied to tubing I3. This will be apparent from the pressurev diagrams in Figures 4, 5, and 6 which representdiagrammatically the character of the variations in pressure, which result in housing 53 and bellows 48. for one embodiment of the invention.

The pressure diagram of Figure l is based upon the assumptions/that the gas pressure in tubing I3 is 500 pounds per square inch, the pressure at the bottom of the oil outow tubing is 400 pounds per square inch, and the intermitter valve 52 and its operating mechanism are so constructed that the valve opens when the pressure in housing 53 is 475A ppundsper square inch and closes when thezpressure lsiiprdslfier square inch?Y TIihese operati ing conditions are selected more or less arbitrarily and may bevaried as desired, except that fthnlfflk pr'essure *atl which the interrriitter valve o pe'nsfi must be something less-than the full gas supply* pressure, andthe pressureat whichthe -intermitel ter valve closes must be more than the pressure irf'fr* theoiltubing.-4 3" If, with` an intermitter valve lconstructed as above described, `the'outlet bleed port 5I has an effectivecross-sectional area approximately three@ times that-of the-inlet 54', the pressure in'fthef housing 53, upon closure of the valve 52, will drop-l along the dottedline 64 until the pressure in 'the' housing53,of 425 pounds per square inch, is reached. Thereuponivalve 52 will close and the' pressurein the housing 53will'r gradually rise, 'as'LL indicated b'y the rising dotted line portion 65, junef'l til l ythe Afpressure again.- reaches "475 ylpounds p'e'rE square inch, whereupon the cycle will repeat-itself.,- The time elapse Ifor a. complete cycle ofV operation-j ofvalve52,;which#is represented `by the horizontal distance onthediagram Figure 4, determinesA the frequencyof the complete filling and blowofl cycle of the chamber 2.` While the pressure in the' chamber 53y is iluctuating-in-general accordance' with the dotted lines 64 and 65, -the pressure in.I the bellows 48 varies inaccordance with the solidy line` in the same i'lgure. Thus, when valve 52 opens,` the pressure in bellows 48 will rise abruptlyf along the vertical line 63 until it equals the pres-D sure in housing 53. The pressures in `housing '53l and the bellows 48-remain equal throughout the period that valve 52 is open, Therefore, the. pressure in the bellows 28, indicated bythe solidi line portion 66, is identical tothe pressure indi-l cated by the dotted line 64 until the pressurev reaches 425 pounds per square inch, at which the Valve 52 closes. From that point on 'the twol -curves depart from each other, since the pressure 1 in housing 53 then rises, while the pressure in the, bellows 48 continues to'drop even more rapidly-l than before, due to the outflow of gas through the opening 5I, until the pressure in the bellows 48; equals the pressure in the outow tubing, i. e.,` the space between housings I I and Id. This more, rapid portion of the pressure drop in bellows 412.,- is indicated by the solid line portion S'I. As soonv as the pressure in bellows d'8 equals the pres-- sure in the outowtubing it remains constant'at4 that pressure until;valve 52 again opens and thenimmediately rises, as indicated by the solid straight line 68, to approximately the pressure in-v housing 53 at the time valve 52 opens.y This comf pletesthe pressure cycle in the bellows I135,- and.v that cycle repeats itself in the same manner. ,z -g Given the pressure curve indicated in solid lines'.4 in Figure 4 for bellows48, itxis apparent that the duration of the blowoff vperiod may be varied with reference to the duration of the complete cyclej by varying the pressure in bellows 4.8 at which the blowo valve 36-is opened. Thus, as indicated irf; the drawing, if thecross-sectional area of the bellows48 is of such size with respect to the area; of port 3l that apressure in bellows 4'8 of 43"#Y pounds per square inch will open the valve 36,1the duration of the blowoff period will be representedy by the length of the dotted line 69 between its; points of intersection with kthe solid lines 68 and, 64, and the duration of the filling period willbe. the remainder ofthe cycle.- Thus, if the duration, of the complete cycle, as illustrated in Figure 4,. istwelve seconds the Yblowoil period will be-'three seconds, and the filling period nine seconds. Ivfon thbeothlec handthe blowoil valve was, onfv structed to open at a lower pressure, the blowoff period would be lengthened at the expense of the filling period. Accordingly, for any given pressure curve for bellows 48, the pressure in bellows 48 at which the valve 36 opens must be so chosen for any given installation as to provide the requisite illling and blowoif periods. In the example given, therefore, the size of the inlet opening of the chamber 2, the capacity of the chamber, and the distance between the inlet opening 6 and the outlet opening 22 must be such that the chamber will completely fill in nine seconds. Since the rate of filling is determined entirely by the'distance between the openings 6 and 22, the size of the opening 8 and the capacity of the chamber, the rate of filling of any givenunit will remain constant regardless of the depth to which it is immersed in the oil standing in the well.

Likewise, in the example given, the rate of blowoii' of the oil from the chamber must be completed in three seconds. This is controlled by the difference in pressure between the gas supply and the pressure in the oil tubing, the size of the oil outletpassages I9 and 20 and the volume of oil in the chamber. These factors may be so correlated as to provide a complete blowof in the blowoff period available.v If, for any reason, a greater proportion of each cycle is required for blowoif and less forv filling it is only necessary to reduce the pressure at which the blowoff valve opens to achieve that result, l

It will be observed that the mechanism so far described provides a means for maintaining a uniform feed of oil to the oil tubing regardless Y.

of variations in the natural level of the oil in the well. Consequently, it is possible to maintain, by means of a constant flow'of lift gas through the bleed opening 45, or otherwise, the ideal gas-oil ratio to produce the most efficient gas lift conditions in the oil outiiow tubing,v and there is no possibility of this ratio being upset by surges of variations in the oil ow. In addition,` the rmechanism entirely relieves the oil formation of the pressure necessary to lift the gas through the oil outflow tubing and, conse'- quently, materially increases the production of the well over conventional gas lift arrangements.

An important feature of the invention resides in the fact that the relative portion of each l complete cycle which is devoted to blowoff and/or the filling period may be materially adjusted by small changes in the pressure of the gas supplied through tubing I3. The effect of such'changes upon the performance of the apparatus depends upon the relative sizes of the openings 5| and 54. If the size of those openings is such that the pressure cycles approximate those illustrated in Figure 4, it is possible, by small adjustments in the gas supply pressure to vary the blowoif period without any appreciable change in the lillng period. This arrangement is advantageous, since the lling rate may be -more easily controlled by the design and construction oi?l the chamber and, being usually a longer period than the lblowoff period, is less sensitive to small vari ations. Moreover, the eiliciency of the unit is less seriously affected by a filling period `which is slightly too long or too short than by a blowoff period which is tooV long.

The manner in which the above mentioned adjustment in the blowoiT cycle is achieved is illustrated diagrammatically in Figures 5 and 6, in which Figure 5 shows the effect of an increase in the gas supply pressure to 510 pounds per square inch, and Figure 6 shows the effect of a decrease in the gas supply pressure to 490 pounds per square inch for the unit, the performance characteristics of which are illustrated in Figure 4.

Referring to Figure 5, it will be seen that the dotted line 10 and the solid line ll, which represent, respectively. the pressure dropping curves for the housing 53 and the bellows 46 after the intermitter valve 52 opens, have a slightly more gradual slope than d o the corresponding lines 64 and 66 in Figure 4, due to the fact that the slight increase in gas supply pressure increases the quantity of gas which enters port 54 during the period that valve 52 is open. Likewise the dotted line 12, which represents the ascending pressure curve for housing 53 when the valve 52 is closed, is steeper than the corresponding line 65 for the same reason. One result of the pressure change in the illustrated diagram is a slight reduction in the period required for the complete cycle. In addition, the increase in gas supply pressure, which is effective on the underside` of valve 36, results in an increase ln the pressure in bellows 48 necessary to open the valve 36. This increase is represented by the higher position of the horizontal line 13 which represents the pressure in bellows 48 at which the blowofi valve 36 opens and closes. As a result of the increase in the height of line 63, as compared with the'height of the corresponding line Ilill in Figure 4, the blowoff period is reduced from three seconds to two and one-half seconds. However, since the complete cycle was slightly shortened the filling period remains approximately the same, or about nine seconds. The slight decrease in the period for the complete cycle, which results in an increase in the frequency of the cycle, slightly increases the rate of flow of oil to the outiiow tubing, thus compensating for the additional supply of lift gas which will be supplied through port 45 as a result of the increase in gas supply pressure.

The blowoil period may be similarly increased, as compared withv that represented in Figure 4, by reducing the gas supply pressure to 490 pounds. Thus, as shown in Figure 6, the reduc tion in gas supply pressure reduces the pressure in bellows 48 required to open the blowoi! valve 36, as indicated by the lower position of the horizontal line 14 as compared with the corresponding line 69 in Figure 4. This increases the blowofl period to three and one-half seconds. In this case the reduction in gas supply pressure slightly increases the period for the complete cycle and' consequently the filling period remains substantially the same, or about nine seconds. The slight reduction in the frequency of the cycle resulting from the reduction in gas supply pressure reduces the rate of flow of oil to the oil outflow tubing to compensate for the reduction in lift gas, which will result from the lower gas supply pressure.

It is apparent from the above that a final adjustment of the blowoff period may be readily made after the mechanism is positioned within the well, by making a small adjustment in the gas supply pressure. Consequently, it is possible to so control the operation of the mechanism by the gas supply pressure as to insure optimum blowoi conditions.

While, as indicated above and illustrated diagrammatically in Figures 4, 5, and 6, it is possible to so construct the mechanism as to permit a variation in the blowoff period without any appreciable change in the lling period by suit- -121 ablyproportioning*the openings 5l andpityis Alikewise pc,ssib1e,'byjchanging the .relative sizes ofthev openings 5L! and .5 74,.to provide a unit l,in which a reduction in 'blowoi period incident to ,changes in the gas supply. pressure will result in a 'morfeor less corresponding. increase in the lling period, and vice versa. This can be accomplished, V: for example, by decreasingthe size of theopening 5l so that the opening of theintermitter valve ,isr delayed to a greater extent than that illustrated'in Figure/l. It will be understood, however, ,thatin allrcases Athe Yopening 5| mustbe larger lthan-the opening .54. "'It willv also beappreciated vthat the frequency of. .-the.1 cycle maybelchanged by changing the will not rise and fall in straight lines, as indicated .on the drawings, and as a practical matter' the 'proper sizes for the bleed openings 5| and 54, as `best determined by trial for any given installation. Since the openings Y arer formed in removable plugs, it is a simple matter to substitute plugs 3 0 having-openingsiof different sizes. In this manner'anyj desired frequency andthe character of pressure cyclesmay be established in the eld beforethe unit is yinstalled. in the well.

12 `4AT gas, operated bottom hole,inter1nitter,. f.or thel uplift of oil through an oil tubingby'ga's under ,pressure in a gas .tubing associated with vsaid `oil tubing, comprising' an oil chamber having nlet and outle'tbil passages adapted to communicate respectively withthe oil standing in tle'well and the .interior oithe oil tubing, a gas pressure pperated valvelmechanism for controlling thefgas pressure intheoil chamber, said mechanism .including a gas chamber and being effective when the gas pressure insaid gaschamber is atone valueto,admitI gas'hunder pressure to saidjoil chanibentodischarge oiltherein and being'eietive when the gas pressure in said gaschavmber is at ,alloy/'er rvalue tp v.disconnect the oil chamber from the gas tubing 'to permit gravity llinggfof saidioil chamber, and pneumatic means kadapted to be connected to the lower endof the gas tubing to elect a periodic jfluctuationdinthe gas pressure lin saidigclambenfrom a relatively constant pressuregas supply lin the gas tubingrfrom vone ,of said twopressures'to the other, said pneumatic nieansinludingnmeans providing a lbleed passage I',ijm...tl-1e,lower endofy the gas tubing into the gas chamber and meansfproviding Va restricted pas,- fsagewofmlarger size than said bleedpassage and cfonnecting the gas chamber to the lowerrrendj'oi thejil tubing and a `,valveloperabl'e' to open said gtriete'djlpassag'e only whenthe pressurein ,the ygas, chamber reaches saidone'value. l' A '2.' A",gas ,operated bottom hole intermitter for I,tliejfiplliit of oil through anoil tubing bygas ,underf lressure in`a"g'as` tubingvassociated with An important'feature of the .invention resides 3.5

iny the' fact that all portions'of theimechanism, .except the filling chamber itself and the ltwo check valves associated therewith, is `fixed to and `removableasa. unit with the macaroni or gas tubing I3, andco'n'sequently, may be removed from A.the well without disturbing the oil tubing. It is thus a relatively simple matter to remove the mechanism for repair` or adjustment.

Another 'important feature lof the invention resides inthe fact that all of lthe relatively slid- .ing parts are entirely sealed againstconta'ct with either` oil or gas.- It is for this'reason that bellows`- are employed in connection with Ithe three valves 52,35, and 42..'7It-will be Vappreciated(,that

from affurictionalY standpoint v ordinary piston operated plungers would servethe same purpose as the bellows but would,vof course, involve relaltive-slidingmemberswhichfare in Contact with the-gas and hence maybecome vcontaminated or 'clogged by waX and other accumulations. ,f Itwillbe understoodvthat theproportions of the mechanism,as shown in the drawings, are distorted to facilitate:illustratin. lztiiall'y the mechanis'mv'shuld be muchY longer, as compared With-its diameter, thanappears from the drawing.' Thus the Vlling chamberrnay be any desired length up to several hundred feetL depending upon thevheight of thelnlatur'al 'oil'level in the well and the rate of production.' All of the expansible 'bellows' employed in the valve `mechanism should be materially/'elongated to reduce the stresses thereondue'rto the small movement required to operate'the valves, and the gas exl haust outlet '22y is preferably located fat a substantial distance above,V the topfot the. lling chamber in order to 'reduce 'the enhaustpressure and thereby increase'the` filling rat f 'the chamber' f "l; ..Q c

' what is claimed ',Saidif'oftubing, Vcornprisinga chamber having ,inlet"and outlet oil passagesV adaptedto communicat respectively' 'with the foil standingin 'the vwe1'1 and une interior of the eil tubing, cheek valves,`A in said Vpassageways, meansv forming a 1rd.. passagewayconnecting the chamberv at. ,a pom't above v'said inlet with fthe low pressure :space outside saidoilfand gasv tubings, said third pss'age-w'ay including a valve seat, a member having a gasl supply passage-adapted to-receive gas from vthe lower end `of the gas tubing, a flow responsive valve-member adapted toV engage said valveseat, said valve member having an opening Ytherethrough communicating with said gas sup- I.ply-,passage whereby said Valve is seated by llow from' said Ygas supply passageV through said .'Valve,land whenlsoseated connects said gas supplypassage to saidrst chamber, said valve when seatedbeing' elective to block` ow from said fstjchambertmsaid lowy pressure space,` and lmean'sdor periodically supplying gas under pressure :to .said Agas vsupply rvpassage from said gas Ltub'ing to cause said valveto periodically engage saidseat.: -f I -y 31A gas operated bottom hole intermitter.y for the .uplift of oil throughr anloil tubing by gas vunder pressure in a gasltubing associated with ,said oiltubing, comprising-a chamber having inlet and outletroil passagesadapted to com-A municatefyrespectively with the oilv standing in .thec-well'andthe interior of the' o iltubing, check valves. .in said passageways, means forming 'a ,third passageway connecting the chamber at a ,point above said inlet with the low pressure space ,outside said. oil and gas tubings, said third 'passageway including Viau/valve seat,- a valve adaptedto eng-age saidseat and thereby block .dow through said passageway between the chamber and said low pressure space, an expanslble ,bellows having one end fixed to said valve in ,axialalignment therewith, a support for the upposite'end of thegbellows, said valve and sup-l port having openingsV communicating with the interior of said bellows, and means for periodically supplying gas under pressure to said opening insaid support from said gas tubing to cause said valve to periodically engage said seat, said valve and seat being so arranged that when the-valve is seated the gas supplied to .said support opening flows through said bellows and said valve into said chamber and such now holds said valve seated.

4. A gas operated bottom hole intermitter for the uplift of oil through an oil tubing by gas under pressure in a gas-tubing associated with said oil tubing, comprising a chamber having inlet and outlet oil passages adapted to -communicate respectively with the oil standing in the well and the interior of the oil tubing, check valves in said passageways, means forming a third passageway connecting the chamber at a point above said inlet with the low pressure space outside said oil and gas tubings, said third passageway including a valve seat, a valve adapted to engage said seat and thereby block flow through said passageway between the chamber and said lowfpressure space, an expansible bellows having one end fixed to said valve inaxial alignment therewith, a support for the opposite end of the bellows, said valve and support having openings communicating with the interior oi said bellows, said valve and bellows assembly including resilient means norvmally tending to disengage said valve from its seat, and means for periodically supplying gas under pressure to said opening in said support from said gas tubing to cause said valve to periodically engage' and disengage said seat, said valve and seat being so arranged that when the valve is seated the gas supplied to said support opening flows through said bellows and said valve into said chamber and such flow holds said valve seated.

5. A gas operated bottom hole intermitter for the uplift of oil through an oil tubing by gas under pressure in a gas tubing associated with said oil tubing, comprising a chamber having inlet and outlet oil passages adapted to communicate respectively with the oil standing in the well and the interior of the oil tubing, check valves in saidY passageways, means forming a third passageway connecting the chamber at a point above said inlet with the low pressure space outside said oil and gas tubings, said third passageway including a valve seat, a gas supply passage, a flow responsive valve member adapted to engage said seat, said valve member having an opening therethrough communicating with said gas supply passage whereby said valve is seated by flow from said gas supply passage through said valve and when so seated connects said gas supply passage to said first chamber, said valve when seated being effective to block flow from said first chamber to said low pressure space, and means for periodically supplying gas under pressure to said gas supply passage from said gas tubing to cause said valve to periodically Aengage said seat, a second valve for controlling said gas supply passage, and pressure operated means for periodically opening and closing said second valve including -a second chamber communicating with said means, said second chamber having a restricted inlet communicating with said gas tubing and an outlet having less restrictive effect than said inlet, a third valve for controlling communication between said inlet and outlet of the second chamber, and means operable in response to a predetermined pressure in said second chamber for opening said valve and eilective when the pressure drops to a lower value to close said valve.

6. A gas operated bottom hole intermitter for the uplift of oil through an oil tubing by gas under pressure in a gas tubing associated with said oil tubing, comprising a chamber having inlet and outlet oil passages adapted to communicate respectively with the oil standing in the well and the interior of the oil tubing, check valves in said passageways, means forming a third passageway connecting the chamber at a point above said inlet with the low pressure space outside said oil and gas tubings, said third passageway including a valve seat, a valve adapted to engage said seat and thereby block flow through said passageway between the chamber and said low pressure space, an expansible bellows having one end fixed to said valve in axial alignment therewith, a support for the opposite end of the bellows, said valve and ysupport having openings communicating with the interior of said bellows, said valve and bellows assembly including resilient means normally acting to disengage said valve from its seat, a fourth passageway connecting said opening in the support with the gas tubing, a second valve for controlling the fourth passageway, and pressure operated means for periodically opening and closing said second valve including a second chamber communicating with said means, said second chamber having a restricted inlet communicating with said gas tubing and an outlet having less restrictive effect than said inlet, a third valve for controlling communication between said inlet and outlet of the ysecond chamber, and means operable in response to a -predetermined pressure in said second chamber for opening said valve and effective when the pressure drops to a lower value to close said valve.

7. A gas operated bottom hole intermitter for the uplift of oil through an oil tubing by gas under pressure in a gas tubing associated with said oil tubing, comprising a chamber having inlet and outlet oil passages adapted to communicate respectively with the oil standing in the well and the interior of the oil tubing, check vvalves in said passageways, means forming a third passageway connecting the chamber at a point above lsaid inlet 4with the low pressure space outside said oil and gas tubings, said third passageway including a valve seat, a valve adapted to engage said seat and thereby block flow through said passageway between the chamber and said low pressure space, an expansib-le bellows having one end xed to said valve in axial alignment therewith, a support for the opposite end of the bellows, said valve and support having openings communicating with the interior of said bellows, said valve and bellows assembly including resilient means normally acting to disengage said valve from its seat, a fourth passageway connecting said opening in the support with the gas tubing, a second valve for controlling the fourth passageway, and pressure operated means for periodically opening and closing said valve including a second chamber communicating with said means, said second chamber Ihaving a restricted inlet communicating with said gas tubing and an outlet having less restrictive effect than said inlet, a third valve for controlling communication between said inlet and outlet of the second chamber, means operable in response to a predetermined pressure in said second chamber for opening said valve andv eiective when the pressure drops to a lower value Ato"clo'se;said valve, said last meansincluding a flexible'bellows in said second chamber having fone end connected to the third valve, a support for the other end of said bellows, the cross-sectional area of said bellows being greater than the effective area of said valve, the space within said bellows being completelyy sealed from the space `Within said chamber, and means resiliently urging said valveltoward closed position.

8."A gas operated bottom hole intermitter for .".the uplift of oilthrough an oil tubing by gas runder pressure in a gas tubing associated with said oil tubing, comprising a chamber having in- Vlet and outlet oil passages adapted to communi- "cate vrespectively with the oil standing in the .ifwell and the interior of the oil tubing, check valves in said passageways, means forming a third passageway connecting the chamber at a point above 'said inlet with the low pressure space outside said `oil vand gas tubings, said third passageway in- ;cluding a valve seat, a valve adapted to engage said seat and thereby block flow through said rpassageway between the chamber and said low pressure space, an expansible bellows having one endxed to said valve in axial alignment therewwith, asupport for the opposite end of the bellows, said valve and support having openings communicating with the interior of said bellows, .said valve and bellows assembly including resilient means normally acting te disengage said rvalve from its seat, a fourth passageway con- :necting said opening in the support with the gas tubing, a second valve for controlling the fourth passageway, and pressure operated means for --periodicallyopening and closing said Valve rincluding a second chamber communicating With svaid means, a third chamber having a restricted rvinlet communicating ywith said gas tubing, a port v,connecting the second and third chambers, a third valve for controlling said port, said port Ywhen open offering less restriction to gas flow than said inlet opening for the third chamber, an-outlet for the second chamber communicating with a low pressure region in said well and hav- ,ing a, restrictive-eiect intermediate that of said third chamber inlet and said port, and means Vfoperable in response to a predetermined pressure in said second chamber for opening said third valve and eflective when the pressure drops to a lower Value to close said valve.

9. A gasoperated bottom hole intermitter for Lthe uplift of oil through an oil tubing by gas un- `der pressure in a gas tubing associated with said pil tubing,vcomprising a chamber having inlet and outlet oil passages adapted to communicate respectively with the oil standing in the well and the interior of the oil tubing, check valves in said passageways, means forming a third passageway connecting the chamber at a point above said inlet with the low pressure space outside said oil and gas tubings, said third passageway including a valve seat, a valve adapted to engage said seat -and thereby block flow through said passageway 'between the chamber and said low pressure space,

`an expansible bellows having one end fixed to Isaid valve in axial alignment therewith, a support for the opposite end of the bellows, said valve and support having openings Vcommunicating with the interior of said bellows, said valve and bellows assembly including resilient means normally acting to disengage said valve from its seat, a fourth passageway connecting said opening in the support with the gas tubing, a second valve for controlling the fourth passageway, and pressure operated means for periodically opening :and closing said valve including a second'chamber' communicating with said means, a third chamber -having a restricted inlet communicating with said gas tubing,'a port connecting the second and third chambersa third valve' for controlling said .port,lfsaid-port when open offering less restriction to gas ow than said inlet opening for thethirdchamber, an outlet `for theseczond chamber communicating with a low pressure region in said well and having a restrictive eiect 4intermediate that of said third chamber inletv -and Asaid port, means operable in response to-a predetermined pressure in Vvsaid second chamber for opening said third valve and effective when the pressure drops to alower value to close said valve,

" :said ,last means including a exible bellowsf in said thirdchamberlhaving one end connected to the third valve, a support for therother end of said bellows, the cross-sectional area of said bellows being greater than the effective area ofy said `thirdval-va thespace `within said bellows ybeing `completely sealed from the-space within lsaid third chamber, and, means resiliently urging said valve toward closed position. s l

10l -A'gas operated-bottom hole intermittergior the uplift of. oil throughan oil tubing by gas under pressure in a gas tubing associated withsaid oil tubing, comprisingfachamber xed to the oil .tubing and having.. an inlet communicating with the oil standing in-lthewell; said chamber having a top closure wall :provided with apassagetherethrough for the flowofoil into said oil tubing, an outflow. tube in4 said; chamber connecting/said oil passage to the lower portion of the-chamber, agas ow passage,throughl said wall, a lthird passage connecting.-the space above said ywall with the spaceoutside-said-oil tubing, v'and -a gas supply valve mechanism fixed to the gastubing Tand removabletherewith independently ofl ,the oil-tubing, said `mechanism .including-means to alternatively supply gas under pressure-to=said gasl flow passage and then connect said gas flow passage to said thirdpassage. fr

.1 11.'A- gas-operated-bottom hole intermitter I or .the upliftA of oil through'an-oil tubing by gas under pressure in a gas tubing'associated with said ,oil tubing-comprising a chamber Xed to the oil tubing and having f anginlet communicating with theoil standing in the well, said chamber having a top closurelwall provided with a passage therethrough for the flow of oil into said oil tubing, an outflow :tubeinsaid` chamber connecting said oil passage to the lower portionof the chamber, a gas flow passage through said wall, a third passage connecting-the space vabove said wall ,with the space outside said oil tubing, and a gas supply valve mechanismv xed to ythe gas tubing and removable therewith independently of the oil tubing, said mechanism including means to alternatively supply gas under pressure to said gas flow passage, then connect said gas flow passage to said third passage, and check valves in said oil inlet and said oil outflow passages.

12. A gas operated bottom hole intermitter for the uplift of oil through an oil tubing by gas un- Ader pressure in a gals tubing associated with said l'oil tubing, comprising a chamber fixed to the oil tubing and having an inlet communicating with the oil standingv in the well, said chamber having a top closure wall provided with a passage therethrough for the flow of oil into said oil tubing, an outflow tube in said chamber connecting said oil passage to the lower portion of the chamber, a gas flow passage through said wall, a third passage connecting the space above said wall REFERENCES CITED The following references are of record in the le of this patent:

Number UNITED STATES PATENTS Name Date Pohle Aug. 10, 1886 Makinster Oct. 13, 1931 Clark Apr. 27, 1937 Stephens et al, Jan. 3, 1939 Crites Jan. 3, 1939 Jennings Jan. 3, 1939 Watson Jan. 23, 1941 Benard Deo. 25, 1945