US1867639A - Apparatus for flowing wells - Google Patents

Description

July 19, 1932. w ss 186E639 APPARATUS FOR FLOWING WELLS Y Filed April 29, 1930 4 Sheets-Sheet 1 ,v 0 m M July 19, 1932. L. WHELESS APPARATUS FOR FLOWING WELLS Filed April 29, 1950 4 Sheets-Sheet 2 July 19, 1932. L WHEILESS 1,867,639

APPARATUS FOR iLOWING WELLS Filed April 29, 1930 4 Sheets-Sheet 3 din m ll

July 19, 1932. E. WHELESS APPARATUS FOR FLOWING WELLS File d Ap1jil 29; 1930 4 Sheets-Sheet 4 w v g 0 tion;

Patented July 19 1932 UNITED STATES PATENT OFFICE EAKIN WHELESS, OF SHREVEPOR-T, LOUISIANA APPARATUS FOR FLOWING WELLS Application filed April 29-, 1930. Serial No. 448,275.

the starting pressure heretofore required in initiating the flowing of the well in those instances where gas or air or other working fluid is utilized in the flowing of the well.

A further object of the invention is to provide an apparatus foruse in air or gas lift wells iii which apparatus there are no ports of valves that are likely to become clogged or are likely to become inoperative by breakage of parts thereof.

In the present method and apparatus, working fluid such as air or gas is injected into the column of liquid to be elevated at successively lower points in the well, and as the fluid comes into contact with the liquid at successively lower points, the uppermost points of Contact are successively eliminated and a further object of the invention is to automatically bring about this successive elimination of the points of contact, so to speak. In other words, there is a series of vertically spaced valves through which working fluid is successively injected, passing first through the uppermost valve and then through successively lower valves, the uppermost valve and successively lower valves being automatically closed as the fluid passes through still lower valves in the well.

With these and-other objects in view, the invention consists in certain details of construction and combinations and arrangements of parts, all as will be hereinafter more fully described and the novel features thereof particularly pointed out in the appended claims.

In the accompanying drawings,

Figure 1 is a vertical view, partly in section and partly in elevation, through the Well casing;

Fig. 2 is a vertical sectional view through a portion of the tubular member that extends downwardly through the well casing, showing one of the valves therein in open posi- Fig. 3 is a similar view, showing the valve of Fig. 2 closed;

Fig. 4 is a similar view, showing a modified form of valve;

Fig. 5 is a view similar to Figure 1, showing the modified form of apparatus; and

Figs. 60;, 6b, and 60 constitute a diagrammatical illustration of the principles involved in an apparatus of the present type.

Fig. 7 shows a still further modified form of apparatus.

In lifting oil from wells by the gas lift method, wells are customarily tubed in such a way that the oil may flow to the surface either through the tube or through the annular space between the tube and the well casing.- The flow is induced or assisted by forcing compressed air, gas or other working fluid into the well under appropriate pressure and in sufficient volume, either down through the tubing or through said annular space, depending upon the path selected for the rising oil. The gas so introduced becomes entrained in the oil or liquid and lightens or aerates the liquid column and by this effort to .expand, carries the liquid upwardly to the surface. The action of gas lift types of apparatus can best be understood by reference to Figs. 6a, 6b, and 60. Fig. (iaillustrates an oil well lined with well casing 10 and equipped with an eduction tube 11. Assuming that during the period in which no oil, is

removed from the well, the oil rises to what is termed an equilibrium position, with the surface of the oil standing at the elevation S above the lower end of eduction tube 11. This high static submergence of theeduction tube is an expression of the magnitude of the rock pressure or maximum expulsive pressure existing within the productive sand. Under these conditions, if compressed air or other working fluid is forced from supply pipe P down into the well between the casmg and tubing, and the latter is left open at the-top and bottom, while the upper end of casing 10 is sealed by a closure 0, the oil level rises within tube 11 as the oil surface in the annular space between the tube and casing is vdepressed. Fig. 6?) illustrates the relative positions of these two oil surfaces within and without the tubing when the gas pressure apbetween those 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 surface. In doing so, it becomes disseminated and entrained 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 as through the oil. As long as this gas, which thus enters the tube, is retained within the oil, its volume serves to further raise the surface of the oil in the tube, and furthermore, as it rises through the tube to regions of lower pressure, it expands and its volume is appreciably increased. If-the volume of the expanded gas added to that of the oil in the tubing is suflicient,,the oil-gas column will be extended upwardly until it overflows at the surface, thereby establishing the flow 0f the oil from the well. These latter stages are illustrated in Fig. 60.

Taking up the matter of pressure conditions existing within the well atthe level of the oil productive sand, the eflective 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'crock pressure within the oil sand and there is, therefore, no tendency for additional oil to enter the well. When, after the gas pressure has been applied and the condition illustrated in Fig. 6b 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 in eduction 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 has been 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 diminish. 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 oil 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 illus the fluid was original trated in Fig. 6a. Under the influence of this reduced pressure, oil now begins to enter the well and as the pressure is further diminished, due to more complete aeration of the rising fluid in the eduction tube, the quantity of oil flowing into the -well from the productive sand will increase until an equilibrium pressure condition is established.

From the above, it is seen that a higher gas pressure is required at the start than is required for theoperation of the gas lift after starting, 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 of the 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 before, 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 is as much as five times as high. Therefore, in addition to the machinery and equipment necessary for pumping a well with the gas lift, it is also generally necessary to main-' tain a considerable amount of other machinery and equipment frequently at a cost of several thousanddollars per well, which is used for starting purposes only and is idlethe 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 operating pressure, and, as before pointed out, the primary object of the present invention is to pro- I vide a method possessing this advantage and ap aratus for carrying out such a method;

tated generally, the method consists in arranging a tube within the well casing, -said tube being provided with a series of ports spaced vertically of the well. Working fluid is then supplied either to the tube or casing,

at which time all the said ports are open.

The oil is gradually depressed as illustrated.v

in Fig. 611 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 ofthe uppermost ports and aerating oil withinsaid tube or within said casing, depending upon whether y supplied to the easing or to the tube. After the fluid has gained access to these three or four ports, the uppermost port is closed and the oil levelfurther depressed until another port is uncovered and.

placed in operation in place of the one closed. All the ports are progressively closed in this fashion, beginning with the uppermost port, a suflicient time interval being permitted to elapse between the closing of successive ports in 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, whichwill, 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, in considerably less than if those above had not been in use. The ports are thus closed in order,-from the u permost one to the lowermost, until eventual y the entire flow of gas will enter 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 thus finally admitted through the bottom opening at a pressure which is very little greater than the pressure necessary to continue operation after starting.

While various forms of apparatus may be utilized for carrying out the method above outlined, the preferred form illustrated in Figures 1 to 3 is of such construction that the closing of the ports at successively lower points in the well may be 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 preferablyv constructed as shown in Figs. 2 and 3. 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 having an internal annular shoulder 16 against which the face of the valve member 17 seat to close the port. Valve member 17 is carried by the tube section next above the section on which 16, 17, but formed on the end face of one of these pipe sections there are one or more lugs 18 that limit the telescopingmovement so as to prevent thev ends of the two tube sections coming into contact with one another. In

this way, when the two shoulders are sep-' arated longitudinally of the tube, there is provided a space 19 between the ends of the adjacent tube sections through which working fluid may flow. I 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 to ether far enough to tightly compress a gas et 20 between them so 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 as that 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 misalinement or curvature of the well hole.

The annular space between the periphery of a shoulder 17 and the inner wall of member 15 is preferably made larger than the very narrow annular space between the inlet surface 16a of shoulder 16 and the exterior surface of the tubing section above shoulder 17 so between the tube and casing; Moreover, a

valve of this type is not apt to become clogged up while in operation.

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, ally of the valves 16, 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 16,17 is made small'enough 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 several of the valves or ports have been uncovered, so that the liquid column in the tube is aerated by them all simultaneously. After the first three or four valves have thus come into operation, the uppermost valve is 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 laced in operation in lieu of. the one close and times. The injection of the working fluid:

through any opening of the tube will aerate the liquid above and decrease its weight, which will, as soon as the liquid commences to flow out of the top of the tube, decrease the liquid pressure at the inlet point in question (and consequently at any point beloW,) so that less starting pressure is then required for the injection of gas at the lower points. Consequently, while the starting pressure at each successlve opening will be greater than at the openings above, nevertheless it will be less than if those openings above had not been used; The valves are closed successively, oneafter 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. This bottom opening may be at the bottom of the string of tubing or itkmay be a joint of perforated pipe or the li e.

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, but preferabl 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' 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 is necessary and the action of the apparatus is entirely automatic. Upon starting up, all of ports 16 in the tubing string may be left 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 wil 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 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 ofthe 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' shutdown the well, as the gas in the cylinder may flowslowly out of the cylin-' der 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 bestarted up again. From the foregoing, it will be seen that this method and'apparatus is'entirely automatic and 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 might be desirable to use a counterweight 28 connected by a flexible member 29, runnin over pulleys 30, withthe upper end of the tu ing string. At

'the pressuresordinarily reva'iling in gas lift operations, the raising o the tubing will not I require very large cylinders. For instance, a cylinder of eight-inch diameter and a pressure of three hundred pounds per square inch is suflicient to lift about four thousand feet of ordinary two-inch tubing having a weight of approximately fifteen thousand pounds- The type of valve illustrated in Figs. 2 and 3 is adapted to use where the working fluid is supplied to the space between the tube and the casing. In some instances, this working fluid is supplied to the tube and the flow of j liquid is upwardly through the annular space 7 above section of the string. As in the case of the valve shown in Figs. 2 and 3, the space between shoulder 48 and sleeve 52 is greater than that between shoulder 51 and the interior of bushing 49. The movement of pipe sections toward one another, in this modified form of valve, is also limited by lugs 54. Where the liquid is flowed from the well upwardly through the space between eduction tube 11 and casing 10, the gas or other working fluid for operating piston 21 ,may be supplied to the cylinder-22 from the compressors or feed line .(not shown) through a pipe 23a, as shown in Fig. 7. The pipe 23a may be provided with a valve 70 for control ling the flow of compressed air to cylinder 22, and said pipe may also be provided with a branch pipe 71, controlled by valve 7 2, for exhausting the compressed air from said cylinder. An arrangement like this, or the equivalent thereof, is necessary in lieu of the connections, shown in Fig. 1, where the compressed air is being admitted through the tube 11 instead of through the inlet pipe 13. It will be understood that where the apparatus is used as shown in Fig. 7 pipe 13 is, in reality, the outlet for the liquid and the tube 11 is the feed line for the compressed air.

In the form of apparatus shown in Fig. 1, the cylinder and piston for elevating the tubing string is shown mounted on the s tufling box constituting the closure for the upper end of the. Well casing. It will be appreciated, however, that these operating portions may be located at other points. For instance, as

shown in Fig. 5, the cylinder may be disposed at the side of the casing and the piston 61 connected with the upper end of the tubing 11 by a cable 62, running over pulleys 63. A counterweight 64 may also be secured on the reach of cable 62 between the cylinder and the pulleys 63, if desired.

While the apparatus and method constituting the present invention have been described as being used essentially for starting gas lift wells it will be appreciated that the same apparatus and the same method may also utilized for what is termed the deliquefieation of gas wells. One of the major problems in the operation of natural gas wells is the removed 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. If allowed to accumulate this liquid will eventually fill the well to a point where the flow of gas from the sand will cease and the Well become dead. This point will be reached when the fluid pressure upon the pro ducing sand, due to the weight of the accumulated column of liquid in the well, approximately equals or exceeds the gas pressure in the sand. 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. Itwill, also, be understood that the rate of accumulation of the liquid in various wells varies with each particular well and the conditions of operation thereof. For

instance, if a high back pressure "is main-' tained 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 very small pipe is used the flow of gas will be kept to a minimum, but on account of internal friction,

entrained liquid particles. The size of the.

pipe must, therefore, be determined by the conditions of thev well, depth, pressure,

amount of fluid to be removed, etc., and a pipe chosen that will 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 discharging with the liquid at the upper end.

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 steam, 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 accumulate 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 an unusually high rate, during peak loads or othenunusual conditions. The remedy usually is to raise the siphon from above until the lower end is near enough the surface of the fluid to permit the siphon to operate 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 expensive process, since the siphon line is packed 01f at the top of the well to prevent leakage 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 deliquefied 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.

There are 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 somewhat higher, the gas openlngs being small enough to maintain the necessary pressure diiferential to cause a column of fluid to stand in the siphon and the lowest .gas inlet being near enough the bottom of the siphon to cause the gas entering through it to pass through the water column. Additional openings are lo cated 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 not pass through the solid water column tonebulize it but instead'is passed above the waterjnoi only not doing any useful work but increas ing the back pressure inside the lower end of the siphon and thereby decreasing the velocity and rate of expansion of the gas at the lower end, and, therefore, decreasing its abil ity tonebulize and pick up water.

In view of this the apparatus and the method of the present invention may be advantageously used for siphoning or deliquefying of gas wells. For instance, the tube 11 with the multiplicity of longitudinally spaced ports may be lowered in the well with its lower endslightly off the bottom so that all the valves may be closed, under which circumstances the tube will serve as a siphon to ele vate liquid entering its lowerend. If, however, the liquid level in the well rises so that the siphon ceases to operate, the'string oftubing 11 is lowered, opening successively from the bottom upwardly as many of the thus removed the siphon string on the string 7 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 raisedto its original position. In other words, where the present apparatus is used as a siphon instead of air or gas under pressure being supplied to the well, the natural gas, commonly under natural pressure, is utilized. I The method herein disclosed and automatic equipment for effectively carrying out the method are disclosed and claimed in my copending application, Serial No. 617 ,840, filed June 17, 1932, as a division and continuation in part of the present application.

What is claimed is:

1. A port valve for use intermediate a sectional string of tubing, comprising a tubular member having means at one end for attachment to one section of said string and having at the other end a radially outwardly extending annular shoulder, and a sleeve member having at one end means for attachment to the other section of said string, said sleeve member being loosely telescoped about the shoulder portion of said tubular member and having an inwardly extending annular shoulder, with which the shoulder of the tubular member is engageable by extension of the members to constitute a continuous tubular section, or separable by relative telescopic movement of the members to constitute a port, said shoulders having concavo-convex engaging surfaces thereby providing perfect seating despite misalinement of the sections of the tubing string.

2. A port valve for use intermediate a sectional string of tubing, comprising a tubular member having means at one end for attachment to one section of said stringand having gageable by extension of the members to con-' stitute a continuous tubular section, or separable by relative teles copic movement of the members to constitute a port.

3. A port valve for use intermediate 8. sectional string of tubing, comprising a tubular member having means at one end for attachment to one section of said string and having at the other end a radially outwardly extending annular shoulder provided with a convex surface, and a sleeve having at one end means for attachment to the other section of said string, said sleeve member being loosely telescoped about the shoulder portion of said tubular member and having an inwardly extending annular shoulder provided with a concave seating surface with which the convex surface of the tubular member is en'- gageable by extension of the members to constitute a continuous tubular section, or separable by relative telescopic movement of the members to constitute a port, and means carried by one of said members for spacing the shoulder of said tubular -member from the sleeve member and the section of the tubing carrying said sleeve member when the seating surfaces of the sleeve and tubular members are disengaged to constitute a port.

4. A port valve for use intermediate a sectional string of tubing, comprising a tubular member having means at one end for attachment to one section of said string and having at the other end a radially outwardly extending annular shoulder provided with a convex surface, and a sleeve having at one end means xfor attachment to the other section of said string, said sleeve member being loosely telescoped about the shoulder portion of said tubular member and having an inwardly extending annular shoulder provided with a concave seating surface with which the convex surface of the tubular member is engageable by extension of the members to constitute a continuous tubular section, or sep- 2 arable by relative telescopic movement of the membersto constitute a port, and spaced lugs on the shouldered end of said tubular member for spacing the shoulder of said tubular m member from the sleeve member and the section of the tubing carrying said sleeve member when the seating surfaces of the sleeve and tubular members are disengaged to constitute a port.

5 EAKIN L. WHELESS'.

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