US1931214A - Apparatus for flowing wells - Google Patents

Description

Oct. 17, 1933. A E. L. WHELESS 1 7 APPARATUS FOR FLOWING- WELLS FiledJuhe 17, 1952 3 Sheets-Sheet 1 HlII-I "II "II" 0d. 17, 1933. E, L, WHELES 1,931,214

APPARATUS FOR FLOWING WELLS Filed June 1'7. 1932 3 Sheets-Sheet 2 z'alrmLwlL zeas,

Oct. 17,1933.

E. L. WHELESS APPARATUS FOR FLOWING WELLS Filed Jun 17. 1932 s Sheets-Sheet 5 Ea/fpuLW/zqkscs,

A 31% Snow; 5

Patented Oct. 17, 1933 v t t a I UNITED STATES PATENT.IQ Q

This application is a continuation, in part, of tion of the eduction tubeextendingdownwardly V my copending application, SerialNo. 448,275,1iled throughthe well casing and,rmore 'part'icularly .i April 29, 1930, now PatentNo. 1,867,639, July 19, of the valve structure providing one of the sev- 1932, and relates to and includes subject-matter eral ports thereof, said valve being inf'open post-j divided out of said copending application. a t on; i

My invention relates to a method and appara- Fig. ,3 is a similar view showing thefialve'of tus for flowing wells and has to do, more particu- Fig. 2'in closed position;

' larly, with the siphonic removal of liquid, such as Figs. 4a, ab and 4c constitute a di'agram'nia'ti oil or water, from wells in which the liquid issubcal illustration of ,the general principles involved ject'to extreme variationsin level because 01 inin gas li t appa a u theme-5 1 typ terrupted use or other causes. i Fig. 5'is' a vertical view, partly in section, part-1 I Under such conditions, it frequently happens ly in elevation, of a modifled form of apparatus that the wells become so flooded as to be constituting a preferred embodiment of. m'yin drowned and must be pumped by auxiliary vention, similarto that illustrated inl' ig. 1, andequipment before the operation of theconvenemploying the hydraulicliftprinciple for. auto 70 tional siphon or gas lift equipmentcan be started. matically regulating the operationof the several It is, accordingly, the primary object of my invenvalves providing ports in the eductionftuben tion to provide gas liftapparatus which will start In l fti g oil from Wells yl 8 fi flow in floodedwells and the operation of which wells are customarily tubed in such a waythat involves no special technique such as partial the oil may flow to the surface either through the 75 withdrawal of the whole, apparatus from the well tube or through the armular space between the t in orderito initiate flow. tube and the well casing. The flow is induced Another object of my invention is to provide an or assisted by forcing compressed air, gas'or other apparatus and method which is economicalin working fluid into the well under appropriate that a minimum of working gas is required, and pre su a d in sumcie t volumer either down so in which the pressures necessary to initiate flow throu t e tub g 0 t rough said annular space, in flooded wells are not materially greater than depending upon the path selected for the those'required to maintainflow when the flooded oil. .The gas so int odu db c es' ent ained condition has been corrected. in the oil .or liquid and, expanding therein, light- Another object of my invention is to provide e s O oe the l q d, 6011mm i lr a gas lift apparatus for flowing wells which ape h qu d upw rdly to the suria'ce. The paratus will initiate flow in a drowned welland ction of gas lift type of -DPM' JS 6811' best be which will automatically regulate itself toprou de stood by re n e o 88. 40, 4b" and'4c. vide a maximum efliciency at the start and as the Fig. 4a illustrates an oil well lined with well caslevel of the liquid in the well becomesdepressed 8 0 d eq pped with an eductlon till-$1511.9

due to continued withdrawal ofliquid therefrom. Duringth Period in which no oil is removed Another object of my inventionis to provide m the W h .oil rises to what .is'termed such an automatic gas lift apparatus for flowing an .equilibrium position, with the surfaceof the wells which may be furnished with compressed oil standin at h Elevation 8 above 40 gas from a remote compressor station. lower end of eduction tube 11'. This high 95 Further objects and objects relating to details static submergence of the eduction tube is and economies of construction and operation will an expressionof the magnitude .of the "rock presdefinitely appear from the detailed description to sure; or maximum exp'ulsive existing follow. In one instance, I accomplish the objects within the productive sand. "Under these, 0 5

of my invention by the means set forth in this tion-s. if compressed airor otherrworklng' fluidjis specification. My invention is clearly defined and for ed from Supply Pi d w nt t fiwell pointed out in the appended claims. Structures between the casing and tubl'ng,jand'the latter-is constituting preferred embodiments of my invenleft openat the top bottom,.while ftheupper tion are illustrated in theaccompanying drawend of casing 10 is sealed by aIelosureQ'the 'oil ings forming a part of this specification, in level within tubers the 'oil slifl8G L-1D which; i 1 the annular space between thetubeyand Figure 1 is a verticalview, partly in section, is depressed. Fig. 4b illustrates the 'remuve opartly inelevation, of apparatus constituting a sitionsof. these twooil surfaces within and withpreferred embodiment of my invention; out the tubing when the gaspressure applied is Fig. 2 is a vertical sectional view through a porsuflicientto depressthe' oil surface between 2 two surfaces to the lower end of the tube. At this point, the high pressure gas or working fluid escapes into the lower end of the eduction tube 11 and moves upwardly toward the s n'face. In doing so, it becomes entrained and dispersed in the oil column in said tube in the form of small bubbles. The viscous condition of the oil and limited cross section of the 'tube prevent rapid translation or "slippage" of the gas through the oil. As long as this gas, which thus enters the tube, is retained within the oil, the displacement'of oil by the volume of gas serves to lower the tubing is sufllcient, the oil-gas column will be extended upwardly until it overflows at the surface, thereby establishing the flow of the oil from the well. These latter stages are illustrated 'inFigJe.

Taking up the matter of pressure conditions existing within the well at the level of the oil productive sand, the effective back pressure on the oil sand opposing the admission of oil, before gas pressure is applied to the well, is equivalent to the static fluid pressure of the oil, below its equilibrium. This, it is assumed, is a pressure substantially equal to the rock pressure within the oil sand and there is, therefore, no tendency l for additional oil to enter the well. After the 35,

gas pressurehas been applied and the condition illustrated in Fig. 4b is attained, the pressure on the productive sand will have been increased to an amount determined by the new height reached by the level of the oil surface ineduction tube 11. As gas enters the tube and aerates the oil therein, there will be an additional, but comparatively slight, increase in the pressure developed'on the oil sand until the oil overflows from the tube at the surface. The pressure developed during this stage, however, is no longer proportional to the height of the oil column, because the latter has acquired a lower density by reason of the working fluid dispersed therein. Up to this point, there hasbeen a continual increase in pressure on the productive sand which prohibits the admission of additional oil to the well, 'but as soon as the oil begins to overflow at the surface, the pressure opposing admission of oil to the well from the productive sand begins to Oil may continue to overflow at the surface only as the result of further aeration of the oil in the tube, the working fluid displacing ofl while the density of the oil-gas mixture in the tube becomes lower and lower and the pressure on the productive sand less and less until eventually the pressure on the productive sand becomes less than the original static pressure established under the starting conditions illustrated in Fig. 4a; Under the influence of this reduced pressure, oil may now begin to enter the well, and as the pressure is further diminished, due

to more eompleteaeration of the rising fluid in the 'eduction tube, the quantity of oil flowing into the well from the productive sand will increase pressure is at the start than is required for' the operationof the'gas lift after starting, 76

because when the gas enters the eduction tube and aerates the oil, the weight of the mixture of oil and gas will be considerably less than the weight ofthe oil column before aerating, and since the pressure at the bottom of the tube depends upon the weight of the fluid therein, it is, of course, less after the oil in the tube has been aerated. Consequently, gas continues to enter the bottom of the tube at a lower pressure after aeration than ,bei'ore, so the operating pressure, or the pressure required for continuing the flow after flow has once been started, is less than the pressure required for starting. The ratio of the starting pressure to the operating pressure varies in different wells, but frequently, in commercial oil wells, the starting pressure must be two or three times as great as the operating pressure, and, in some cases, it isas much as five times as high. 3 Therefore, in addition to the machinery and equipment necessary for pumping a well with the gas lift, it is also generally necessary to maintain a considerable amount of other machinery and equipment, frequently at a cost'of several thousand dollars per well, which is used for starting purposesonly and is idle the remainder of the time. From this, it is evident that a great saving can be effected in gas lift operations by a method that will permit starting at a pressure practically equal to or very little in excess of the 'ly depressed as illustrated in Fig. in until the working fluid has access to the'uppermost port of said tube. The oil is then still further depressed until the working fluid has access to the next lower port and so on, until the working fluid is flowing through some three or four 'of the uppermost ports and aerating oil within said tube or within said casing, depending upon--whether the fluid was originally supplied to thecasing or to the tube. cess to these three or four ports, the uppermost port isclosed and the oil level further depressed until another port is uncovered and placed in operation in place of the one closed. All the ports After the fluid has gained acare progressively closed in this fashion, beginning with the uppermostport, a suflicient time interval being permitted to elapse between the closing of successive portsin order-to allow the fluid level to be depressed or to recede so as to keep one or more valves uncovered and in operation at all times. The injection of fluid through any opening of the tube will aerate the fluid above and decrease its weight, which will, as soon as the'fluid commences to flow out at the surface, decrease the'fluid pressure at the inlet point in question, and consequently at any point below it, so that less starting pressure is then required for the injection of fluid at lower points.'- The starting pressure at each successive lower port, although greater than at those above, is considerably lessthan if those above had not been in use. The ports are thus closed in order,

from the uppermost one to the lowermost, until eventually the entire flow of gas willenter the discharge pipe through the bottom opening, which may be at the bottom of the string of tube, as

shown in Figure 1, or some other form of opening at any desired point in the tube. The fluid is 1 ports at successively lower points in-the well maybe accomplished automatically by means operable by the working fluid utilized for flowing the well. In this apparatus, the upper end of casing 10 is sealed by a closure C having a packing gland c for packing material 12, through which the eduction tube 11 extends. At a point immediately below closure C, there is an inlet pipe 13 for supplying working fluid to the interior of casing 10, and at points spaced suitable distances apart longitudinally of the eduction tube 11, there are ports provided in said tube, these ports being preferably constructed as shown in Figs. 2 and 3 and claimed in my copending application, Serial No. 448,275, now Patent No. 1,867,639, Julyl9, 1932, above referred to. These ports or valves consist of a bushing 14 threaded internally so that it may be secured on one section of the tube and threaded externally for the attachment of what would be termed a port member 15. These port members are in the form of a sleeve havi an internal annular shoulder 16 against which the face of the valve member 1'! seats to close the port. Valve member 17 is carried by the tube section next above the section on which the bushing 14 is secured. The tube sections are capable of being moved longitudinally of one another to seat and unseat the shoulders 18, 17, but formed on the end face of one of these pipe sections there are one or more lugs 18 that limit the telescoping movement so as to prevent the ends of the two tube sections from coming into contact with one another. Inthis way, when the two shoulders are separated longitudinally of the tube, there is provided a space 19 between the ends of the adjacent tube sections through which working fluid may flow. These valves or ports are shown in their open position in Fig. 2, and in their closed position in Fig. 3. The threads on the exterior of bushing 14 are preferably straight threads and the bushing and port member 15 are adapted to screw together far enough to tightly compress'a gasket 20 between themso as to make a tight joint. The internal diameter of the inner member of this valve arrangement, i. e.,' that member on which shoulder or valve face 17 is formed, is practically the same asthat of the tubing string so as not to interfere with the flow of the aerated liquid. The outside diameter is practically the same as that of the tubing except for an external annular shoulder at one end to cooperate with the annular shoulder 16 on the valve member 15. Preferably, the annular shoulders 16, 17 are concave and convex, respectively, so that they will maintain complete contact even if the tubing string does not hang perfectly straight, due to mlsalinement or curvature of the well hole. The annular space between the periphery of shoulder 17 and the inner wall of member 15 is preferably made larger than the very narrow annular space between the inlet surface 184 of shoulder 18 and the exterior surface of the tubing section above shoulder 17, so thatam foreign matter which might pass through this last-mentioned e will easily pass through the first-mentioned passage. A port clearance of .010 of an inch between the shoulder 16 and the tubular portion carrying the shoulder 1'1 has been found most practical from the standpoint of efllciency as well as sufllcient to permit the tubing to conform to deviations in the well bore without interference. While the spacing of the valves in the tubing string may vary with various well conditions, a practical working arrangement uniformly satisfactory for use in general air lift operations is as follows:

Spacing from valve Distance from below bottom Lowest valve oint) oints) 14th lowest 16th lowest m' 2400 tmuao 300 feet 15 The present form of valve is exceedingly simple and very rugged. item be used at any depth; does not require adjustments; and takes up such a comparatively small amount of space that it will not interfere with flow, either in the eduction tube or in the air space between the tube and easing. Moreover, a valve of this type 3 not apt to become clogged up while in opera- In flowing a well, the lower end of the tubing string rests upon the bottom ,of the well or is supported by the well liner or other suitable support and, in starting, all of the valves 18, 17 in the string will be open, due to the weight of the "pipe, which telescopes'the. section ends to open said valves. Gas forced into the annular space between the tubing and the casing under pressure will depress the surface of the liquid in this space until it reaches the uppermost valve, at which point a portion of said gas will flow into and aerate the liquid column within the tube. The annular opening constituting these ports or the spaces between the valve members 18, 17, is made small enough-about .010 of an inch-so that a single valve can accommodate or pass only a small part of the entire amount of gas or working fluid being forced into the well casing. The liquid level in the casing will, under these conditions, continue to be depressed until a number of the valves have been opened to provide ports and the liquid column in the tube is aerated by them all simultaneously. After the flrst three or four valves have thus come into operation, the uppermost valve may be closed (preferably by means hereinafter described), and the liquid level between the casing and tubing will be further depressed until another valve is uncovered and placed in operation in lieu of the one closed, and by progressively closing all the valves in order, beginning with the uppermost one, the working fluid is forced to still lower valves and is progressively inJected into the tube through a series of points successively located at lower positions along the tube. A suflicient time interval should lapse between the closing of successive valves in order that the liquid level may recede ahead of the last closed valve sufnciently to keep several valvesuneovered and in operation at all times. The injection of the working fluid been used. The valves are closed successively,

paratus may be left entirely automatic.

one after the other, from the top, and those below are successively brought into action until eventually the entire flow of gas will enter the eduction tube through the lowermost opening in the manner shown in Fig. 40. This bottom opening may be at the bottom of the string of tubing or it may be a joint of perforated pipe or the like.

This progressive closing of the valves from the uppermost one downwardly of the well is accomplished by the' gradual raising of the tubing string. As the string is slowly raised, it effects the closure of the top valve and then of each succeeding one downwardly. of the well. This raising or elevating of the tubing may be effected in various ways, as for example, by means of a piston 21 working in a cylinder 22, mounted on the top of closure C. Piston 21 is connected or attached to tube 11 and a portion of the working fluid from supply pipe 13 is conducted by a pipe 23 to the interior of cylinder 22. A highly restrictive valve 24, preferably a needle valve, is interposed in pipe line 23 in order that the flow of working fluid to cylinder 22 may be regulated in accordance with the rate at which the liquid level in the well is depressed. A reservoir 25 connected by a branch 26 to pipe 23 may also be provided for. the reception of a portion of the gas passing valve 24, if it is found that the tubing string must be raised at an exceedingly-low rate of speed. After valve 24 has once been set to give the proper flow for the well in question, no further manipulation of that valve, by a well attendant, is necessary and the action of the ap-' v Upon starting up, all of ports 16 in the tubing string will be in their telescoped or open position, and while the major portion of the gas passes downwardly between the casing and tube to depress the liquid and uncover successive ports or valves, an appropriate portion of such gas will, at the same time, flow through pipe 23 and valve 24 into cylinder 22, slowly building up in the cylinder suflicient pressure to raise the piston 21 and the tube. As each valve is closed, the weight or load imposed upon the piston is increased so that additional pressure is required in the cylinder for continuing the elevation of the string, and when the piston has reached the top limit of its travel, the relationship provided by the valve 24 should be such that the liquid level will have reached the bottom opening in the tubing. Ordinarily, the valve 24 would be the only fitting necessary in line 23, but, if desired, other fittings may be used in this line for gauges and the like. Unless a very slow upward movement of the tubing string is desired, reservoir 25 may be dispensed with. If it is desired, either temporarily or permanently, to have the flow of liquid from a point higher in the well than at the lowermost opening, the length of the travel of the piston in cylinder 22 may be regulated by suitable means, such as adjustable stops 27. In this way, the back pressure on the productive oil sand during operation may be readily regulated. The opening of the needle valve 24 need not be changed when the gas is cut off to shut down the well, as the gas in the cylinder may flow slowly out of the cylinder through the valve, allowing the tubing to settle down gradually. Under such conditions, the tubing will return to its original position in a comparatively short time, with the several valves telescoped or open and ready for the well to be started up again. From the foregoing, it will be seen that this apparatus is automatic in that, once adjusted to the particular well, it does not require the presence of anyone at the well to attend to it, even when the gas is being furnished from a distant compressing station.

Under some conditions, it may be desirable to use a counterweight 28 connected by a flexible member 29, running over pulleys 30, with the upper end of the tubing string. At the pressures ordinarily prevailing in gas lift operations, the raising of the tubing will not require very large cylinders. For instance, a cylinder of eight-inch diameter and a pressure of three hundred pounds per square inch is sufficient to lift about four thousand feet of ordinary two-inch tubing having a weight of approximately fifteen thousand pounds.

While I have described the present invention as employed with a well easing into which the eduction tube through which the well liquid is forced to the surface is disposed, it is obvious that the procedure may be reversed, employing the well casing as the eduction duct and the inserted tube as the duct for introducing the compressed working gas. Likewise other designs of valves peculiarly adapted for either one or the other mode of liquid eduction may be employed. Two forms of valves are disclosed and claimed in my prior application Serial No.

' 448,275, now Patent N0. 1,867,639, July 19, 1932,

to which reference has previously been made.

In Fig. 5 of the drawingsI have shown a somewhat rnodifled form of tubing string elevating apparatus for appropriately governing the actuation of the several valves in accordance with pumping progress. As in the apparatus shown in Fig. 1 there is provided a piston 81 working in a cylinder 82 mounted on the topof a well casing closure or head C. Piston 81 is coupled to tho eduction tube 11 and may be limited in its upward extent of movement by threaded stops 27. A compressed gas duct 13 is threaded into the closure C and communicates with and supplies the well casing 10. For the purpose of providing a lifting effort upon the under side of the piston 81, there is provided a tank 85 for oil, glycerine or other suitable hydraulic lift fluid, the level of which is shown at x. A small duct 83 for compressed gas leads from the well casing cap C and, controlled by a highly restrictive valve 84, provides an extremely slow discharge of gas from the well casing head into the air space of the tank 85. An oil supply duct 86 leads from the sump 85a of the tank into the cylinder 82 and, as gas pressure is slowly being built up in the tank 85 by the gas passing through the highly restrictive valve 84, oil is slowly displaced from the tank 85 into the pipe 86, gradually filling the cylinder 82 and raising the piston 81. By means of appropriate adjustment of the valve 84, the piston movement may be timed to effect tube elevation in accordance with the characteristics of the well, which in most instances are fairly uniform from day to day during the active life of the well. This apparatus, once adjusted, may,

like that shown in Fig. 1, therefore be employed as an automatic system dependent solely upon the supply of compressed gas, even though from a remote source.

While the apparatus and method constituting the present invention have been described as being used essentially for starting gas lift wells itwill be appreciated that the same apparatus and the same method may also be utilized for what is termed the deliqueflcation of gas wells. One of the major problems in the operation of natural gas wells is the removal of liquids such as oil or salt water which continue to flow or seep into the bottom of the well from the gas sand along with the gas. It allowed to accumulate this liquid will eventually flll the well to a point where the flow of gasfrom the sand will cease and the well become dead. This point will be reached when the fluid pressure upon the producing sand, due to the weight of the accumulated column of liquid in the well, approximately equals or exceeds the gas pressure in the same. The rate of gas production. will, of course, decline in proportion to this pressure of the liquid if the liquid level rises in the well. It will, also, be understood that the rate of accumulationoi' the liquid in various wells varies with each particular well and the conditions of operation thereof. For instance, if a high back pressure is maintained upon the sand the inflow of liquid will be less, and when the back pressure is lower, by increasing the rate of gas discharge from the well, the liquid will flow faster and, therefore, accumulate more rapidly. Ordinarily, this accumulated liquid is removed by means of a siphon line constituted by a string of comparatively small pipe run from the top of the well to the level from which it is desired to remove the accumulated liquid, and open at the top to permit free discharge of the gas to the atmosphere. If a small pipe is used the flow of gas will be kept to a minimum, but on account of internal friction the velocity may not be great enough to get the greatest efficiency in the lifting of the entrained liquid particles. The size of the pipe must, therefore, be determined by the conditions of the well, depth, pressure, amount of fluid to be removed, etc., and a pipe chosen thatwill remove the desired amount of fluid with the least expenditure of gas. The simplest form of siphon contains no other openings than those at the two ends, the gas entering at the lower end and disc a ging with the liquid atthe mend.

when the fluid level rises as high as the lower end of the siphon, gas flowing through the siphon will pick up small particles of the liquid and carry them up and out in. much the same way that particles of moisture are carried in wet stream, that is, the liquid is in the disperse phase and supported in and raised by the gas by virtue of its velocity. If the water should enter the well faster than it is removed the liquid level will, of course, build up to the point at which the siphon will become inoperative and the liquid will socumulate still faster thereafter until the well is' dead. This frequently happens when the back.

pressure in the well is lowered by withdrawing the gas at anunusually high rate, during peak loads or other unusual conditions. The remedy usually is to raise the siphonfrom above until the lower end is near enough the surface of the fluid to permit the siphon to operate and then to lower it again after enough water has been removed to permit it to operate at a lower position. This, of course, is a slow, troublesome and spacing of approximately 20 feet at and above' around it, and these packing members must be removed to permit the passage of pipe couplings. Also, equipment for the raising'and lowering of: the tubing must be procured, or kept on hand for the purpose. If the well is not entirely dead it may be deliqueiied in this way with its own gas; but if its own flow has practically stopped, gas must be introduced into it from some other source.

Thereare other varieties of siphons in general use following the general principle of admitting. water into the siphon at the lower end and the gas at points somewhathigher, the gas openings being small enough to maintain the necessary pressure differential to causes. column of fluid to stand in the siphon and thelowest gas inlet being near enough the bottom of the siphon to cause the gas entering through it topass through the water column. Additional openings are located somewhat higher so that if the fluid level rises and seals off the lower opening, gas will still be admitted to the siphon line and pass through the water column therein. The utility of these higher openings under ordinary conditions, that is, when the lowest opening is in operation seems to be in dispute, but it would seem that they would really be worse than useless until those openings below were closed, because the gas entering through the higher openings'would 106 not pass through the solid water columnto nebulize it but instead is passed above the water, not only not doing an'v useful work but increasing the back pressure inside the lower end of the siphon and thereby decreasing the velocity and rate'of-xllo expansion of the gas at the lower end, and-therefore, decreasing its ability to nebulize and pick up water.

In view of this the apparatus and the method of the present invention may be advantageously used for the siphoning or deliquefying of gas wells. For instance, the tube 11 with the multiplicity'of longitudinally spaced ports may be lowered inthn well with its lower end slightly off the bottom so that all the valves may be closedfiunder which circumstances the tube will serve as a'siphon to elevate liquid entering its lower end. If, however, the liquid level in'thewell rises sothat the siphon ceases to operate, the string of tubing 11 is lowered, opening successively from the upwardly as many-ofthe in the string as may be neoessaryto again start the siphon'in action, itbeing that the gas produced inthe wellwillsntertheopenedportstoproduce the siphon action. when enough water has been-.130 thusremoved, the siphon string or the strlng of tubing 11 is again raised, closing one or more'of the valves or ports and diverting the gas to a lower point of entry and so on until the tubing is finally raised to its original position. In other words, where the present apparatus is used as a siphon instead of air orgas under pressure being supplied to the well, the natural gas, commonly under natural pressure, is utilized. When using the present apparatus and method for re-, moving water from drowned gas wells, it is preferable to arrange the valve spacing in the inverse order, that is, with a spacing of from 40 to 60 feet at the bottom, graduating upwardly to. a

the high water level. A practical working arrangement for use in a siphon system requiring a tubing string having a fifteen valve ported portion of 600 feet is as follows: 60 foot spacing (3 Joints) 'between-each of the five lowermost valves. 40

foot spacing (2 joints) between each of the five intermediate valves, and 20 foot spacing (1 joint) between each of the five uppermost valves. This diiference in spacing order over that found most expedient in the air lift pumping of oil wells is due primarily to the fact that the natural pressure of the gas will ordinarily increase as the well is being drained. Moreover, flooding troubles requiring the present system most commonly occur in old gas wells in which production and pressure has declined due to partial exhaustion.

I am aware that the form and mode of operation of my preferred apparatus may be varied considerably withoutdeparting from the scope of the invention. For example, instead of relying upon the needle valve 84 in the gas line 83 of my apparatus illustrated in Fig. 5 as the piston movement-determining element, I may employ the valve 87 in the oil supply duct 86 for the same purpose. Due to the greater restriction capable of attainment upon a liquid, the use of a highly restrictive needle valve in the duct 86 is not so essential, though, under some circumstances, it may be desirable.

What I claim is:

1. The method of initiating and maintaining flow from a well in which the liquid stands at a level higher than that normal to the operation of the well, which comprises extending an openended liquid eduction tube into the well to the level to which the liquid in the well is to be lowered, maintaining gas under pressure in the well,.,space about said eduction tube and upon the surface of the liquid in said space to depress thelevel of said liquid therein and raise the level of the liquid in said eduction tube providing a static column of liquid in said tube above the depressed level of the liquid in said well space, simultaneously injecting gas under pressure from said'well space into said liquid column in said tube at a plurality of vertically spaced points, permitting said injected gas to rise through, expand, and aerate said liquid column, reducing the density thereof to such an extent as to enable the pressure in said well space to so raise said aerated liquid in said tube as to cause flow therefrom, continuing the injection of said gas from said well space into said tube at said vertically spaced points to lower the liquid level in said well space, and progressively lowering the injection points as the level of the liquid in the well space is lowered.

2. The method of initiating and maintaining flow from a well in which the liquid stands at a.

level higher than that normal to the operation of the well, which comprises extending a pair of open-ended tubular members into the well bore,

to the level to which the liquid in the well is to be lowered, one of said tubular members being disposed within the other, thus providing distinct inner and outer ducts, maintaining gas under pressure in one of said ducts, thereby depressing the level of the liquid therein and raising the level of the liquid in the other duct simultaneously, injecting small streams of the gas from the gascharged duct into the column of liquid in the other duct at a plurality of vertically spaced points to aerate said liquid column and so decrease its density as to cause the upward pressure upon the bottom thereof due to the greater weight of the liquid in said gas-charged duct and the gas pressure thereon to effect discharge of the aerated liquid from its duct, continuing the injection of said gas into said flowing column of liquid to reduce the amount of liquid in said well, and progressively lowering the points of injection as the level of the liquid in the gas-charged duct is lowered.

3. A semi-automatic apparatus for intermittently flowing a well subject to flooding when not continually pumped, comprising a well casing, a liquid eduction tube extending downwardly within said casing to the level to which the well isto be pumped, means for providing gas under pressure in the space between the well casing and said tube, a plurality of telescoping valves disposed at vertically spaced positions. along said tube, associated therewith to provide vertically spaced gas injection ports at said positions, closed when said tube is suspended and successively openable in upward order by progressively supporting more and more of the weight of the tube upon its lower end, a cylindena piston in said cylinder and coupled to said tube to raise and lower the same and control the adjustment of said valves so that gas is injected through several valves simultaneously,. a cylinder charging duct communicating with said gas space between said well casing and said tube, and a restriction in said duct automatically regulating the rate of cylinder charging to provide valve actuation by said piston and lowering of the gas injection points in conformity with the rate, of depression of liquid level in said well casing.

4. A semi-automatic apparatus for intermittently flowing a well subject to flooding when not continually pumped, comprising a well casing, a liquid eduction tube extending downwardly within said casing to the level to which the well is to be pumped, means for providing gas under pressure in the space between the weli casing and said tube, a plurality of telescoping valves disposed at vertically spaced positions along said tube, associated therewith to provide vertically spaced gas injection ports at said positions, closed when said tube is suspended and successively openable in upward order by. progressively supporting more and more of the weight of the tube upon its lower end, a cylinder, a piston in said cylinder and coupled to said tube to raise and lower the same and control the adjustment of said valves so that gas is injected through several valves simultaneously, a-cyiinder charging duct communicating with said gas space between said well casing and said tube, and an adjustable, highly restrictive valve in said duct automatically regulating the rate of cylinder charging to provide valve actuation by said piston and lowering of the gas injection points 'in conformity with the rate of depression of liquid level in said well casing.

5. A semi-automatic apparatus for intermittently flowing a well subject to flooding when not continually pumped, comprising a well casing, a

liquid eduction tube extending downwardly within said casing to the level to which the well is to be pumped, means for providing gas under pressure-in the space between the well casing and said tube, a plurality of telescoping valves ,disposed at vertically spaced positions along said tube, associated therewith to provide vertically spaced gas injection ports at said positions, closed when said tube is suspended and successively openable in upward order by progressively supporting more and more of the weight of the tube upon its lower end, a cylinder, a piston in said cylinder and coupled to said tube to raise and lower the same and control the adjustment of said valves so that gas is injected through several valves simultaneously, a cylinder charging duct communicating with said gas space between said 1,981,214 well casing and said tube, a flow-restricting valve in said duct, and a gas reservoir having connection with the portion of said duct intermediate said valve and cylinder, said cylinder, flow-restricting valve and reservoir being so proportioned with respect to the rate of flow of liquid and gas into and out 01' said well and the weight of the eduction tube as to provide valve actuation by said piston in conformity with the rate of depression oi liquid level in said well casing.

6. A semi-automatic apparatus for intermittently flowing a well subject to flooding when not continually pumped, comprising a well casing, a liquid eduction tube extending downwardly within said casing to the level to which the well is to be pumped, means for providing gas under pressure in the space between the well casing and said tube, a plurality of telescoping valves disposed at vertically spaced positions along said tube, associated therewith to provide gas iniection ports at said positions, closed when said tube is suspended and successively openable in upward order by progressively supporting more and more of the weight 01 the tube upon its lower end, and oil lift means for eii'ecting raising of said eduction tube to provide accurate actuation of said valves in accordance with draining of the well and depression oi oil level in said well casing, said means comprising a cylinder, a piston disposed therein and coupled to said eduction tube, a reservoir for a quantity of oil, a cylinder charging oil duct. communicating with said reservoir, a reservoir harging gas duct communicating with said well casing, and a highly restrictive valve regulating displacement or oil from said reservoir into said cylinder.

EAKINLWHELESS.

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