US2679212A - Gas lift apparatus - Google Patents

Description

May 25, 1954 R. G. NISLE l-.TAL 2,679,212

GAS LIFT APPARATUS Filed June 23. 1952 5 sheets-sheet 1 INVENTOR. ROBERT G. N/SLE BY F. H. PQE r TMA/wv wm fz@ P RE 5S URE May 25, 1954 R. G. NlSLE ETAL GAS LIFT APPARATUS Filed June 25, 1952 F/GZ K/CK- OFF E PRESSURE OPERA TNG PRESSURE 5 Sheets-Sheet 2 OPERA T/NG PRESSURE PRESSURE T/ME INVENTOR. ROBERT G. N/SLE F.H.`POE7`7'MANN May 25; 1954 R. G. NlsLE ErAL GAS LIFT APPARATUS 5 sheets-sheet :s

Filed June 23, 1952 R. 0E WLM mnea7 TM mp. MH. F y# B 2 9 5 llml 7 8 6. 8

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Patented May 25, 1954 GAS LIFT APPARATUS Robert G.. Nisle; and Fred H. Poettmann, Bartlesville, Okla., assignors toV Phillips Petroleum Company, a corporation of Delaware Application June 23, 1952, Serial No. 294,986

16 Claims. (Cl. 10S-232) This. invention relates.v to gas, liftv apparatus, particularly for controlling the. rate of' flow of pressurized gas into gasV lift wells` In gas lift operations, gas is introduced into the interspace between the tubing and casing of a well. The pressurized gas'y thereby introduced aerates the oil and causes` it to flow upwardly through the tubing to the surface of the well. In such systems, the tubing advantageously extends a short distance below the level ofthe oil being. produced, or alternatively, the tubing is perforated' adjacent theY upper level of the oil to be produced.

In starting the gas lift operation, the pressure iin the interspace is initially sufficiently high as to force the oil upwardly through the tubing. Asthe operation begins, alternate pressure drops and pressure risesoccur until the pressure reaches an operating value substantially lower than the initial pressure, at which' timeoperati-on is stabilized. A similar pressure fluctuation is observed when a well dies due to a change in the operating conditions ofthe system. When the conditions change in suchmanner that the gas input rate is insuicien-t to maintain flow, the level of the oil inthe well rises above the lower end of the tubing er, alternatively, `the upper end of the perforated portionof the tubing. Thereupon, the pressure in the well increases since no gas canl pass upwardly through the tubing under these conditions. The pressure increases until the oil level is depressed' below the bottom of the tubing or, alternatively, below the perforated portion of the tubingy at which time gas will be vented out through the tubing and the pressure in the interspace between the tubing and casing drops until' the liquid level again rises to close off the bottom ofthe tubing. Successive pressure iiuctuations of this type occur with increasingly greaterV amplitude until the well ceases to flow, at which time the pressure in the interspace is ata high value above, the normal operating pressure but below the initial pressure required to start operation of the well.

It has been previously proposed to control the gas input to a gas lift well in such fashion that less gas is admitted when, the well pressure decreases and more. gas is fed automatically to the well' as the pressure increases, the advantage being that gas is conserved in that no more than the amount required to maintainow is'supplled to the well at any time.

In service, wells areY periodically visited by a purnper who makes periodic checks' of well operation. Inasmuch as both pressure rises and pressurer drops are characteristic of a: dying well, in accordance with-:this invention,y the rate ci flow of gas is increased whenever there is: either an excessive drop or any excessive, rise in pressure. In this manner, consistenti` operation. is' maiutained so long as the system operates; in. stable fashion without excessive pressure fluctuations. Although slightly more gas-,maybe required under certain conditions, ther cost of the additional gas is more than odset by the stable operation cb,- tained and positive preventionA of production stoppage. If a higher than normal` amountof gas is consumed during a period of automatic operation, the condition of the, well can be checked. bythe pumper at the next inspection and corrective steps taken.

Itis an object of the invention toprov-ide alitomatic control means for a gas. lift pumping system that preferably prevents the. stopping of produc.- tion under manyadverse operating conditions-` Itis av further object to provide. a gas lift pumping system which is. reliable in operationv and which can be added` tov existing pumping equipment. with little expenditure of time or material.

Various other advantages, objects andi features of the invention will become apparel-1t` fromv the following detailed description taken in conjunction with. the accompanying drawings, in which:

Figure 1 is a perspectiveview of' the gas lilft apparatus of' this invention;

Figures 2 and 3. are graphs illustrating-the operation of a gas lift pumping system;

Figure 4 isa vertical sectional view, partially in elevation, of the pressure-responsive device of Figure 1;

Figure 5 isa perspective View of a modied form of control apparatus for a gas lift system;

Figure 6 is a vertical sectional View, partially in elevation, of a still furtherv mod-ined' control system;

Figure 7 is a sectional view taken along the lines 1 1 of Figure G looking in the directionof the arrows; and

Figure 8 is adetail view of a portionof FigureV 6.

Referring now-r to Figures 2i and 3, Figure 2'illustrates pressure-variations which occur when operation of the gas lift well is initiated'. It will be noted that the pressure in the interspace between the tubing and casing first rises to an initial kick-oli pressure at which flow is initiated. Thereafter, the pressure fluctuates about the line labeled operating pressure, the fluctuations becoming 'of' progressively decreasing amplitude stable conditions areV reached at the operating pressure. Figure 3 illustrates the conditions observed when a well dies, that is, ceases to produce. It will be noted that pressure variations of progressively increasing amplitude occur about the line labeled operating pressure due to the rise and fall of the oil level in the well, as previously explained. When production stops, the pressure reaches a stable value intermediate the kick-off pressure and the operating pressure. It will be noted, therefore, that both increases and decreases in pressure relative to the line labeled operating pressure are characteristic of an unstable gas lift operation which, if not checked, will cause the well to stop flowing. In accordance with this invention, whenever such iuctuations in pressure appear, whether they are increases in pressure or decreases in pressure, the rate of ow of gas is progressively increased until stable operation is again attained.

In Figure 1, we have shown a well having casing I and tubing Il, the tubing extending through a casinghead I2 to an outlet pipe I3, and having perforations I4 formed therein adjacent the level of the oil being produced. Alternatively, it will be understood that the tubing may be mperforate and extend to a region just below the level of the oil. In order to obtain gas lift production, gas is fed to the interspace or annulus I5 between the tubing and casing through a gas input line I6, the gas aerating the oil and lifting it to the surface through the tubing I I.

operatively associated with the input line i6 is a rate of flow controller I1 which includes a dow-sensing device I8 and a valve VI3 which is opened or closed automatically to provide a rate of flow as determined by the setting of the controller. Controller Il can be of any suitable type, and preferably has a pointer which is manually set to the desired rate of flow, this pointer being moved by a flexible cable in the manner hereinafter described to control the gas lift operation. The setting, in turn, is controlled by mechanism 2li including a pressure-sensing device 2I responsive to the pressure in the interspace i5 adjacent the surface of the well. The operation of mechanism 2) is such that either a predetermined increase or a predetermined decrease in the pressure within the interspace adjacent device I causes a stepwise increase in the setting of rate of flow controller II which produces a predetermined increase in the rate of flow of gas to the well. Each time the flow is increased, there is a `possibility that operation of the well will become stable at the new gas input rate. lf such stable operation occurs, no further action of the controller is caused. However, if an increment in the ow rate does not produce stable conditions, further fluctuations will produce additional increments in the flow rate as necessary until stable operation is obtained.

It will be noted that the pressure responsive device 2| includes a laterally protruding cylindrical casing 22, Figures l and e, within which is mounted a bellows 23 exposed to the pressure existing within the interspace I5. The bellows has secured thereto a rod 24 which extends through a housing A25 and is pivoted to an arm which, in turn, is pivoted to a link 2. The position or link 2T, therefore is representative of the pressure existing within the interspace I5 adjacent the surface of the Well.

The rectilinear movement of link 2 is transmitted to a lever 28 pivoted at 29 to a support 3IJ, this lever carrying a set of contacts 3|, 32. Cooperating with the contacts 3i, 32 are contacts 33 and 3d, respectively, which are secured to contact arms depending from a member or assembly 35 also pivoted at 29 to the support Both contacts 33, 311 are connected in circuit with a winding 36 of a solenoid-actuated ratchet mechanism 3l, a current source, not shown, and the contacts 3 I, 32 carried by the lever 28. When this circuit is closed by engagement or contacts 3i, 33, or 32,34, the solenoid winding 3E is energized and a pawl 38 produces a stepwise movement of a ratchet Wheel 39. The position of ratchet wheel 33 is transmitted by a flexible cable il to the ilow controller Il in such fashion that the position of the ratchet wheel controls the position of the set pointer of the controller and, hence, the rate of 'low of gas through input iine it. The movement of link 2l is also transmitted to a lever 43, one end 44 of which is pivoted to link 2l and the other end 6,5 of which is supported by springs 46, Il secured to a mounting bracket d8. A lever 49 is pivoted at d@ to the lever 43, one end of the lever i5 being secured to a dash pot 5I and the other end of lever d being connected by links 52 and 53 with the pivoted member 35 so that the position of the contacts 33, 34 is controlled by the position of lever in operation, assuming that the well is operating normally and the operating pressure is stable, contacts 3l, 32 are positioned between and out of engagement with contacts 33, 3@ with the result that ratchetmechanism 3l is deenergized and rate of iiow controller causes a proper amount of gas to be supplied to the well to maintain equilibrium conditions. Should an operating variable of the system change so as to cause unstabie operation of the well, the operating pressure begins to fluctuate in the manner shown by Figure 3. Assuming that the rst fluctuation produces a pressure increase, the resulting movement or" link 21 responsive thereto causes lever 28 to move in a counterclcckwise direction, Figure l. If the increase is of greater than a predetermined extent represented by the initial spacing between contacts 3l, 33, these contacts are closed with the result that ratchet mechanism 3l is energized to cause one stepwise movement of ratchet wheel 39 with aresultant increase in the setting of the controller il and increased rate of fiow of gas through line I6.

The described movement of link 2i also produces rightward movement, Figure i, of the .lower end fili of lever d3. This rapid movement cannot be .followed at pivot pointv due to the dash pot 5I which resists any abrupt change in the lateral position of pivot point 5e. As' a result, lever pivots about point 53 in a counterclocirwise direc tion, thereby storing energy in the springs t, which thereupon tend to restore the end fr, to its original position. The energy thus stored in the springs 45, lil produces a slow clockwise pivoting of lever 43 about pivot point i4 at a rate determined by the dash pot 5 I. As a result slow leftward movement of lever [lil occurs which, by the action of links 52 and 53, causes a countercloclrwise movement of member 35 and the contacts 33, 34. That is, the initial comiterclockwise movement of lever 28 is followed by a slower corresponding counterclockwise movement of member 35. If stable conditions are obtained as a result of the described single actuation of ratchet mechanism 3l, the contacts 3 i, remain positioned intermediate the xed contacts Se and no further corrective action takes place. However, should the pressure increase continue, a further counterclockwise movement of lever 2S occurs resulting in a second closure of contacts ting: controller il..

decrease, in pressure within interspace l, leftaard'. rectilinear movement of link 21 results and lever 28. is: moved. in a clockwise direction. If the extent; of; this movement is. greater than the initial; spacing; between contacts t2@ 3A, there is an actuation ,ci ratchet, mechanism 3'! and an increase, in the gas lio-vv rate4 as a result. of resetmovement, of 2l= produces a slow clockwise tollowirlg `movement of member 3.5 due to the action of springs 45,41 and dash po-t 5l so that, the; Oigilnal, increase in flo-W- rate does not result stable. operation, there is a secondl closure of contacts 3,2,- 3.4 and a. further increase in the gas npnt rate. Such cycles continue `until stable operation of the system. is attained.

it will be evident, therefore, that either an. increase; orv decrease in pressure of greater than a predetermined extent, representedv by the initial spacing; between contacts 3-| 3.3. and 32., 34 resuits: stepwise increases in the rate. of flow of gas through line l5, such stepwise increases. contim-ting until stable. operation is resumed. The nowrate cheeked by the operator at. each inspection, and, the operator can take steps to correct any condi-tions leading tothe unstable operation. corrected by the automatic operation of the. control system which resulted in an increased or greater than normal rate of flow of gas through the line. lli.

In Figure 5. we have shown a system wherein the levers and. pivots of Figure 1 are replaced by gearing. In this, structure, the linkI 211' of Figure 1 is connected to.- a rack Eli which is shifted longitudinally in accord-ance withl changes in pressure With-in the interspaee, la. Rack 5,5 drives a spur gear 5.5. carrying a lever 5i and. contacts. 58, 59

yCorrespondingv to. the lever 28- andcontacts 3|, 32

of Figure 1. Rack 55, also dri-ves; a spur gear 6s which is connected gear 6,! to a shaft 62 coupled to a gear E3 of a dineren-tialY mechanism te. The mechanism 6,4 also includes a gear S5 to which are secured springs t@ and 6l tending to bias a shaft 68 carrying gear E5 to. a predetermined angular position. The mechanism te further includes a ring gear t9y within which is carried a pair ofpinions l!! and 'll meshing with the gears, $23 65. Rotation of the ring gear is. transmitted through gearing l2 to a shaft 73. At the upper end ci shaft.. isa spur gea-r 1:4; meshing with a rack l5. which is` operatively connected to a dash. pot i6.. Rotary movement. of shaft. 'i3 is also. transmitted.. throughl gearing 'il and 1.8, to, a member 1.9 carrying contacts 3.0. and al cooperating with the contacts 5,8. and., 55., respectively. Rotation ot shaft T3.. produces a clockwise or counterolockwisef movement of. member 19. depending upon. the direction of shaft rotation. The contactsY 58, 8.0 and 59., 8.1; are connected in circuit with thasolenoid acti-iated ratchet, mechanism 3'! and rate of flowcontroller Il, inthe manner describedinconnection withriigure 1.

f It. will ha apparent that, the lever 5ft moves, in a The described rightward counterolockwise or clockwise direction responsive.- to increases or decreases; in pressure in the manner explained connection with the lever 2s of Figure 1. Movementv of the lever 5 1 in either direction. is followed by a slovvY correspondingmovement of the member 19 se thatv successive increases in g-a-s nom rate are made until a stable; condition is reached. For example, it Will be noted that a rightvvardmovement,.Figure 5, of rack) 55 produces a. counterclockwise movement of lever 511. Such movement ofthe rack is; trans- Hritted to gear 63; of' diierential mechanism 6,4 and', as shaft 'i3 cannot move rapidlyl due to its connection to dash not 1.6i, theY motion of shaft 62 is transmitted to gear e5. and shaft t8` which rotates ina reverse direction and. stores. energy in springs 66. and 6.1. These springsf cause shaft 68: to slowly move back toward its original position- With resultant rotation of shaft 13 and gear B9 at av rate. determined by the dash pot? 'iti This slow rotation of sh-aft 13 is transmitted through gearingv 11, le to member 19 and produicesra slow counterclockwi-se movement. thereof. in the same direction as the movement of lever 5l; it will be; evident` that a. leftw-ardf movement of the rack 55 producesa clockwiseI movement of liever 51 and a slow' following clockwise movement of member 18.- due to the action of springs 66, 6l' and` dash pot is. Hence, the system functions inr the same manner as the system of Figure 1 except. that the pivots, links, and levers are; replaced by gears and shafts, which are more suitable in certain applications.

In Figures 6,. 7, and 8, We have` shown a system wherein the electrically-actuated' ratchet mechanism. isreplaced by a pneumaticallyactuated ratchet mechanism., thereby permitting the control device to be used at. Well locations where electric current is not available. In this modification, the link 21. of Figure l is connected to a rackv 8.5 meshing with teeth formed on a disk 8,6. Formed in the disk 36 is a nozzle 31 to Which instrument airor other gas under pressure is ed.. through a line 83 Slidabl-y mounted outside the disk i8 is a sector-shaped member 89 which carries. a pair of communicating ports si! and 9 1, both ports. communicating with a passage 9 2, leading. tov an outlet line. 93.. The angular position of sector-shaped member Bef-is controlled by a rack 94 meshing with teeth formed on the outer surface of sector-shaped member Se.. Outlet. line. 5.3 leads. to. a. piston chamber 15 having a piston roots.' protruding therefrom. which is connected by a. lever 5J pivoted at 98 to a sup.- port 99., Also. pivoteol to the.. lever al. is a pawl l'llll which cooperates, with a. ratchetv Wheel lill.

ln operation ratchet Wheel l0 E. is mechanically connected; to the set. pointer of unit l1 asv in Figure 1,. so. that the setting of the controller is rdepenclent upon the. angular position of the ratchetv Wheel.. Rack. as connected to a, suitable. dashpot. and spring mechanism of the character described, in Figures 1 and 5 so as to produce a Slow angular movement. of sector-shaped member 5,9. in the, same. direction as movements o disk Bloaused by pressure. changes. in the interspaoe. l5; For example., rack a5 can be conheated, to, the pivot point. 41S.' ofl lever i3 of Figure l.. and rack 9i?, can be vconnected to. the lever A9 of Figure.' 1.VV In. this modiication, an increase in pressure causes a rightward movement, Figure- 6 of rack fk5, and. acounterclookwise movement, of disli- 85. It this movement is. of sumeient extent as to cause nozzlefti te register with portv di), air under pressure is fed through line 93 to piston chamber 95 with the result that a stepwise movement of ratchet wheel I l is produced by pawl mi). Thereafter, port 90 moves slowly in a leftward direction, Figure 6, so that the nozzle 3l is once more positioned intermediate the ports 99, 8! and no air is transmitted to piston chamber N1. li the increase in gas now rate caused by the den scribed movement of ratchet Wheel IUI produces stable operation, no further operation oi the system occurs. However, if there is a further increase in pressure, a further counterclockwise movement of disk 8S occurs and the system passes through another corrective cycle. lt will be evident that a decrease in pressure produces a clockwise movement of disk 3S which causes operation of the ratchet wheel and now controller if the pressure change producing rota tion of the disk is of sufficient magnitude as to cause nozzle 8l to register with port 9 i. Further, responsive to such clockwise rotation of the disk 8B, there is a slow clockwise movement of sectorshaped member 89 so that the apparatus is in readiness for a new cycle of operation if stable operation is not caused by the initial operation of the ratchet mechanism and flow controller.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and is not intended to limit the invention.

We claim:

l. in gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a pressure-responsive device having a sensing element in said interspace adjacent the surface of the well and producing an output representative of 'pressure in said interspace, a rate of flow controller in said line determining the rate of flow of pressurized gas into said interspace, and mechanism operatively connected to said controller and responsive to the output of said device, said mechanism actuating said controller so as to increase the rate of flow of gas responsive both to a predetermined increase and a predetermined decrease in the pressure represented by the output of said device.

2. ln gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well, and oil is aerated and lifted through the tubing by such gas, in combination, means for producing an output representative of the pressure in said interspace, and mechanism controlled by said last-named means to increase the rate of flow of gas into said interspace responsive both to a predetermined increase and a predetermined decrease in the output of said pressure-responsive means.

3. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a rate of iiow controller in said gas input line, a pressure-responsive device producing an output proportional to the pressure in said interspace, and control mechanism operatively connected to said rate of ow controller and responsive to the output of said pressure-responsive device, said mechanism including means for establishing an initial maximum allowable pressure above the normal operating pressure in said interspace, means for establishing an initial minimum allowable operating pressure below the normal operating pressure, and means for operating said controller so as to increase the rate of flow of gas into said interspace when the pressure rises above said maximum allowable value or falls below said minimum allowable value.

Il. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a rate of flow controller in said gas input line, a pressureresponsive device producing an output proportional to the pressure in said interspace adjacent the surface of the wall, and control mechanism operatively connected to said rate of flow controller and responsive to the output of said pres sure-responsive device, said mechanism including means for establishing an initial maximum allowable pressure above the normal operating pressure in said interspace, means for establishing an initial minimum allowable operating pressure below the normal operating pressure, means for operating said controller so as to increase the rate of ilow of gas into said interspace when the pressure rises above said maximum allowable value or falls below said minimum allowable value, and means responsive to such rise or fall of pressure to reset said initial maximum value and said initial minimum value to new values which are different from the initial values by an amount corresponding to the pressure increase or decrease.

5. In gas lift apparatus for a system wherein gas is introduced into the interspaoe between the tubing and casing of a well, and oil is aerated and lifted through the tubing by such gas, in combination, a pressure-responsive device communicating with the interspace between the tubing and casing adjacent the surface of the well, said device including a movable member whose position is representative of said pressure, means cooperating with said member and actuatable upon a predetermined movement thereof either in a direction representing a pressure increase or in a direction representing a pressure decrease, means controlling said cooperating means to cause it to follow the movement of said member, said last-mentioned means including a damper, whereby the following movement of the cooperating means is slower than the corresponding movement of said member, and means responsive to the actuation of said cooperating means to increase the rate of flow of gas into said well by a predetermined amount.

6. In gas lift apparatus for a system wherein is introduced into the interspace between the tubing and casing of a well, and oil is aerated and lifted through the tubing by such gas, in combination, a pressure-responsive device communieating with the interspace between the tubing and casing, said device including a movable member whose position is representative of said pressure, means cooperating with said member and actuatable upon a predetermined movement thereof either in a direction representing a pressure increase or in a direction representing a pressure decrease, means controlling said cooperating means to cause it to follow the movement of said member, said last-mentioned means including a dash pot operatively connected to said cooperating means, a spring, means responsive to movement of said member to store energy in said spring, means for releasing the energy stored in said .spring so as to move said cooperating means at a speed determined :by :said dash pot. whereby the following movement of the cooperating means is slower than the y:corresponding movement of said member, and means responsive to each actuation of fsaid cooperating means to increase the rate oi flow Aof gas into said well by a predetermined amount.

7. In gas lift apparatus for a system wherein gas is introduced into the interspaoe between the tubing and casing vof a well through a gas input line, and foil .is aerated `'and lifted tinough 'the tubing by such gas, in combination, a pressureresponsive device 'communicating with the interspace between the tubing :and casing, said 'device including a movable member whose position is representative of said pressure, rneans cooperating with said member andactuatable upon a predetermined movement thereof :either in a .direction representing a pressure increase or .in 4a direction representing 'a pressure decrease, means controlling 'said coope'rating means to cause it to follow the movement Yof said member, 'said .lastmentioned means including 'a damper, whereby the following movement of the cooperating means is slower than thc correspond-ing movement of said member, a rate 'of iiow controi'l'erop:r

eratively connected to 'said .gas `input line, `and pawl and ratchetmeans responsive to `each factuation of said Acooperating means 'to increase the setting of said 'rate of fiow controller and thereby the gas input rate in 'a lvstepwise manner.

8. In a gas lift apparatus .for a system wherein gas in introduced into the interspace between the tubing Aand `casing of fa well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, .a pressureresponsive device communicating with the in'terspace between the tubing 'andfca'sing adjacent the surface of the well, said device including fa '.-movable member `whose position is 'representative of said pressure, means cooperating with 'said mfember and actuatable upon a predetermined movement thereof either in L'a direction representing a pressure increase 'or in a direction representing 2a pressure decrease, 'means fcontrollin'gsaid cooperating means to cause it to Ifollow the movement of said member, `said last-mentioned means iincluding a dash `pot operatively .connected to said cooperating means, a spring, means responsive to movement of said .member to store renergy iin said spring, means for releasing the energy stored in said spring so as to 'move said cooperating means at a speed determined by said dash pot, whereby the following movement of the cooperating means is slower than the corresponding movement of said member, a vrate vof flow controller operatively connected to `said vvgas .input line, and pawl and ratchet means responsive to each actuation 'of said cooperating :means to increase the setting `of Vsaid vrate :of flow controlier and thereby the gas input irate ina-stepwise imanner.

9. In gas lift apparatus for a 'system wherein gas is introduced into 'the 'interspace between the tubing and casing of .a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a pressure-responsive device communicating with the interspace between the tubing and casing adjacent the surface of the well, said device including a lever whose position is representative of said pressure, said lever carrying a pair of electrical contacts, a movable pair of contacts cooperating with the contacts on said lever and actuatable upon a predetermined .movement thereof either in a direction representing a pressure increase or in a direction repersenti-ng :a pressure decrease, a rate ci now controller operatively connected with said gas input line, solenoid operated ratchet mechanism actuatable to increase the setting of said contro-lier ina stepwise `manner so as to increase the rate or ilow of fgas, and a circuit including a current source, said solenoid, said lever and said movable contacts, said circuit being arranged to actuate Asaid solenoid mechanism each time the lever engages one oi said contacts.

i0. In gas ii-ft Vapparatus for a system wherein gas in introduced into the interspace between the tiring and casing of a well through a gas input line, and 'cil is aerated and lifted through the tubing by suc-h gas, in combination, a pressure-responsive device communicating with the interspace .between the tubing and casing, said device including a Alever whose :position is representative of said pressure, said lever carrying a pair ci contacts, a pivoted member carrying a pair of contacts vcooperating with -contacts on said lever, one set of contacts being closed upon a predetermined movement of said lever in a direction representing a pressure increase, and the other set Aof contacts `being closed upon a predetermined movement of said lever in a direction representing a pressure decrease, means controlling said pivoted member to cause it to follow the movement of said `lever at aslower rate than the corresponding movement of said lever, said controlling means including a spring, means responsive to movement of said lever for storing energy in said spring, a dash `pot operatively connected to said ,pivoted member, means for imparting the energy of said spring to said pivoted member at a rate deter-mined by said dash pot so as to effect sai-d following .movement of the pivoted member, a rate of flow controller operatively connected in sai-d gas input line, solenoid operated ratchet mechanism to increase the setting of said controller in va stepwise manner responsive to each soienoid actuation, and a solenoid-'actuating circuit including said solenoid, a current source, said lever cont-acts, and the contacts on said pivoted member, said -circuit being closed upon each engagement of either of said sets of contacts.

ii. In Igas .lift apparatus for a system wherein gas in introduced into the interspace between the tubing and casing of `a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a bellows communicating with the interspace between the tubing and casing adjacent the surface of the well, a vpivoted lever bearing a pair of contacts, a linl connecting lsaid bellows to said lever, an arm pivoted to said link, a spring assembly connected to said arm in such fashion that movement rof the 'arm in either direction stores energy in said springs and tends rto return said arm to its original position, a rod pivoted upon said arm, a dash pot connected to one end of said rod, a pivoted :movable contact assembly secured to the other end of said rod, said assembly including a pair-oi contacts cooperating with the contact set. upon said lever, solenoid-actuated ratchet mechanism having a solenoid winding connected in circuit with both` contacts of said assembly and the contact set of said lever, a rate of iiow controller in said gas input line, and means for transmitting rotation of the ratchet to said controller so as to vary the setting thereof.

12. In gas lift apparatus for a system wherein- 1l gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a bellows communicating with the interspace between the tubing and casing adjacent the surface of the well, a rack movable by said bellows, a lever bearing a pair of contacts movable by said rack, diierential gear mechanism having three members, one member being geared to said rack, a spring assembly connected to another member of said differential gear mechanism in such fashion that movement or" said last-mentioned member in either direction stores energy in said springs and tends to return said member to its original position, a dash pot geared to a third member of said dierential gear, a pivoted movable contact assembly geared to said third member, said assemthe contact set upon said lever, solenoid-actuated ratchet mecha-nism having a solenoid winding connected in circuit with both contacts of said assembly and the contact pair on said lever, a rate of rlow controller in said gas input line, and means for transmitting rotation or the ratchet to said controller so as to vary the setting thereof.

13. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a pressure-responsive device communicating witn the interspace between the tubing and casing adjacent the surface of the well, said device including a movable member whose position is representative of said pressure, a rotatable nozzle whose position is controlled by said member, a pivoted assembly having a pair of ports cooperating with said nozzle so that communication is established between one of said ports and said nozzle upon a predetermined movement oi the nozzle in either direction, means for supplying fluid under pressure to said nozzle, a rate or" iiow controller in said gas input line, and pneumatically-operated ratchet mechanism actuatable to increase the setting of said controller in a stepwise manner so as to effect an increase in the rate of flow of gas, said ratchet mechanism being pneuniatically connected to both of said ports so as to be actuated when said nozzle registers With either port.

14. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a pressureresponsive device communicating with the interspace between the tubing and casing adjacent the surface of the well, said device including a movable member whose position is representative oi said pressure, a rotatable nozzle whose position is controlled by said member, a pivoted assembly having a pair of ports cooperating with said nozzle so that communication is established between one of said ports and said nozzle upon a predetermined movement of the nozzle in either direction, means for causing said pivoted assembly to follow the movement of said nozzle, said last-mentioned means including a damper constructed and arranged to slow down said following movement of the pivoted assembly, means for supplying fluid under pressure to said nozzle, a rate of flow controller in said gas input line, and pneumatically-operated ratchet mechanism actuatable to increase the setting of said controller in a stepwise manner so as to eiect an increase in the rate of flow of gas, said ratchet mechanism being pneumatically connected with both of said ports so as to be actuated when said nozzle registers with either port.

15. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by such gas, in combination, a bellows communicating with the interspace between the tubing and casing adjacent the surface of the well, a rack movable by said bellows, a rotatable nozzle, the position of which is determined by the position of said rack, a cooperating rotatable member including a pair of ports which register with said nozzle upon a predetermined movement thereof in either direction, means controlling said cooperating means to cause it to follow the movement of said nozzle, said last-mentioned means including a damper, whereby the following movement of the cooperating means is slower than the corresponding movement of said nozzle, a :fate of ow controller in said gas input line, and pneumatically-operated ratchet mechanism actuatable to increase the flow setting of the controller in a stepwise manner, means for supplying air under pressure to Said nozzle, and means for eecting communication between both ports and said pneumatically-actuated ratchet mechanism.

16. In gas lift apparatus for a system wherein gas is introduced into the interspace between the tubing and casing of a well through a gas input line, and oil is aerated and lifted through the tubing by Such gas, in combination, a bellows communicating with the interspace between the tubing and casing adjacent the surface of the well, a rack movable by said bellows, a rotatable nozzle, the position of which is determined by the position of said rack, a cooperating rotatable member including a pair of ports which register with said nozzle upon a predetermined movement thereof in either direction, means controlling said cooperating means to cause it to follow the movement of said nozzle, said last-mentioned means including a differential mechanism having a first gear member geared to said rack, a second gear member geared to said cooperating rotatable member, and a third member, means biasing said third member to a predetermined angular position, and a dash pot operatively connected to said second member, a rate of now controller in said gas input line, and pneumatically-operated ratchet mechanism actuatable to increase the iiow setting of the controller in a stepwise manner, means for supplying air under pressure to said nozzle, and means for eiecting communication between both ports and said pneumaticallyactuated ratchet mechanism.

No references cited.

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