US2227539A - Apparatus for flowing wells - Google Patents

Description

:Jam 7, 1941n H. T. Dom-@N APPARATUS FOR FLOWING WELLS Filed Oct. 24, 1939 2 Sheets-Sheet l Han/ey 7.' oron.

N O T R U D L H APPARATUS FOR FLOWING WELLS Filed Ot. 24, 1939 2 Sheets-Shee; 2

floured Jan. 7, i941 NITED STATES PATENT OFFICE This invention relates .to .the control of fluid ilovv in eas and oil wells. and more particularly to methods and apparatus for selectively cont-rolling und measuring the injection of gas orother :duid

il into a plurality of diierent strata. of an oil produel sand for the purpose of artificially stimulatinu ythe recovery of oil therefrom, and for also controlling the now of oil and gas from a produclnu well by the use of a series of vertically i 1; i ced ports inthe well tubing which it is desired to selectively vary in effective size or completely close as the iiowing progresses.

in repressuring oil producing sands by the lniection oi eas iroin a pressure Well, it has been lord that the permeability of the sand varles urcutly in dierent strata, and that a materially diderent pressure muy be required for the injection oi the desired volume oi gas into one strat thun is required tor another. inasmuch as it would not be economical to maintain a series ol uuscommessors or reservoirs discharging at diii'erent pressures into a multiplicity of strings oi tubinu leading to the different strata, it n heretoiore been the practice .to control the pres sure ci the pas injected by the use oi pressure reducinu restrictions in the tubing.

it has been i'od, however. that when such restriction are installed at the Well heads, it is practically possible .to main-tuin a continuous lilou oi eas into a well when the atmospheric temperature is at or near freezing, without the applicution oi heat in some forni, because the eitpuusion oi .the gas in passing through u. dow restrictinu orihcc reduces its temperature to a point where any liquid entrained in the gas'or otherufise .present et the oridce quickly ireeucs and clous the latter. To avoid :this cuity. it has been proposed to install such restrictions in the vvell tubing at points sufficiently far below the s'iace oi .the uround to insure that .the temperature olthe expanded gas remains above freezing. The ai with this arrangement, however. is .that Whenever it becomes necessary to change the eine oi" u restricting orifice-and this is a more or less i'requent occurrence because oi the continually changing conditions in the sand dunne vieil operation-either the entire tubinu strips ust he removed from the well to enable replace meut oi the oridce litting, or .the latter must be elevated inside the tubing and another litting lovvered into place by the use of suitable tools. hoth of these procedures are time consuming and occasion the loss of substantial quantities of gas because of the necessity for blowing,r down the well euch time that the orifice fitting is changed. The

disadvantages of these prior practices are, of course, multiplied in the case where a plurality of strata in the same sand are to be repressured simultaneously, because, as far as is known, no satisfactory, commercially practicable method has hitherto been devised for this purpose which does not require the use of la separate string of tubing for each stratum.

Somewhat similar problems are also involved in restricting the production of oil and gas Wells, because oi the desirability from. the standpoint of emciency providina e. plurality of ports in the tubing at diierent levels and near .the face of the producing sand.

It is therefore one oi the objects of .the present invention .to provide new and improved procedures and apparatus ior controlling the flow of Iiuids in gas and oil Wells which will overcome the dimculties and remedy the defects heretofore encountered and existing in .the methods and means previously available to the art for attaining the same ultimate results.

Another object is to provide novel land simplilied means for regulating and metering the flow oi duid into or out of a gas' or oil well ait a piurali-ty of .points located substantial distances belou' the suriuce oi the ground, and ior readily varying from the well head the regulatory eect ot such means.

,A further object is to provide a new method and apparatus ior varying .the sizes oi a number of iioW restricting nttings in a single tubing string of a pressure or producing well winch does not reduire either the use of tools for placing and removing the ttings or the removal of the tubing string from the well. v

Still another object is .to provide an apparatus oi novel construction by which the injection of iiuid into a plurality of diierent strata of a pressure well may be selectively regulated and metered through a sinele string of tubing.

A still further object is to provide a novel method and apparatus of [the character described which are capable of effecting substantial savings in .the cost of oil endg-as Well operationswherein it is necessary to restrictively control the ilow oi duid to or from .the Well at a number of different levels therein.

These and other objects will appear more fully upon a consideration of .the detailed description of the embodiments of the invention which follows. Although two specic forms of apparatus embodying the present invention are described and illustrated in the accompanying drawings, it is to be expressly understood that these drawings are for the purpose of illustration only and are not to be construed as defining .the limits of the invention, reference being had for this latter purpose to .the appended claims. 5 Referring now .to the drawings, wherein like reference characters indicate like pants throughout the several views:

Fig. 1 is a vertical sect/lon, with certain elements shown in full and others broken away in the interest of clarity, of one arrangement of apparatus embodying the present invention adapted for controlling and metering :the flow of gas or other uid into a plurality of dlerent strata of a pressure well for Ithe purpose of artificially stimulating the lrecovery of oil from producing wells in the same eld by injecting iiuid under pressure into the oil producing sand;

Fig. 2 is a fragmentary vertical section, on an enlarged scale, of the flow controlling fittings of the apparatus of Fig. 1;

Fig. 3 is a vertical sectional view, similar to Fig. 1, of a second embodiment of the invention especially adapted for use in a producing well; and

Fig. 4 is a fragmentary vertical section, on an enlarged scale, of the ilow controlling fittings of the embodiment of Fig. 3.

In each of the two embodiments of the invention illustrated, the apparatus disclosed is adapted to restrictively control the flow of a fluid into or out of a single string of tubing through a plurality of ports located at various distances below the surface of the ground, and includes elements, hereinafter `referred to as port plugs, which determine the effective sizes of the ports, or close them entirely, and are capable of being lowered to and raised from the points of control by means of gravity 'and fluid pressure alone. In each instance, the points of 40 the tubing string at which flow regulation is required are provided with fittings forming seats for the plugs and embodying ports of a fixed maximum size, the eective sizes of which are varied by the plugs, while the upper end of the 45 well tubing is provided with a suitable arrangement of valves, pipe connections and other means by which the plugs may be raised from and lowered to their seats without the use of fishing or other tools.

Referring now more particularly Vto the embodiment illustrated in Figs. 1 and 2, there is indicated therein a pressure well Il containing a single main string of tubing I2 which is adapted to extend downnwardly to the producing strata 55 I3, I4 and I5 of the oil sand into which a repressuring fluid is to be injected. In a typical oil sand, the producing strata I3, I4 and I5 are of different permeabilities and are separated from one another by impermeable, non-productive 00 strata such as shale formations IS, I'! and I8.

Since the most eflicient recovery of oil from the entire sand is obtained by so regulating the flow of the repressuring fluid injected into the various strata that the strata of higher per- 65 meability are subjected to lower pressures than those of less permeability, suitable means are provided for selectively controlling and metering the ow of fluid into each of the strata I3, Il and I 5.

70 To this end, there are threaded into the tubing string I2 at vertically spaced points opposite the dierent producing strata iittings I9, 20

and 2|, each of which is provided with a port 22, 23 and 24, respectively, of such size that, when unrestricted, it will pass fluid from the interior of tubing string I2 at the maximum pressure which it may be desired to inject into the producing stratum. The fittings i9, 26 and 2i are all preferably of the same outside diameter as the tubing I2 so as to form a string of uniform size throughout its length, thereby enabling the use of identical packers 25 for sealing ofi from one another the individual portions of the well which communicate with the producing strata i3, ICI and i5.

In order to suitably restrict-and, when desired, completely shut o--the ow through ports 22, and 2d of the gas or other fluid used for injection, ilttings l, 2@ and 2i are provided with internal, downwardly tapered seats 25, 2l and 28 which are adapted to receive and support in readily removable association therewith members known as port plugs 23, 39 and 3i, respectively. In the case of fittings i9 and 2t, the ports 22 and 23 entend horizontally and intersect the tapered surfaces of seats 2@ and 2l intermediate the upper and lower ends thereof, while in fitting 2i the port 2li is located below the tapered seat 38. In order that the plugs 29, 3@ and 3I may be seated and removed in the manner contemplated by theI present invention, the minimum internal diameters of the tapered seats and the maximum external diameters of the port plugs decrease correspondingly to their relative positions with` respect to the top of the well. That is, the mammum outside diameter of the plug 33 adapted to cooperate with tapered seat 2l is less than the minimum internal diameter of tapered seat 26, although greater than that of tapered seat 27, so that said plug may pass freely through fitting I3, but not through tting 2li. Similarly, the maximum outside diameter of the plug 3i adapted for cooperation with tapered seat 23 ise less than the minimuminternal diameter of tapered seat 21, but greater than that of seat 23.

All of plugs 29, 30 and 3l are generally cylindrical in form, have their bottom ends tapered as indicated to make tight ilts. with tapered seats 2E, 2l and 23, and are provided with vertical bores 32, 33 and 34 through which the fluid passes. Each of the plugs is also preferably rounded or tapered at its upper end as shown, and the lower surface of each tapered seat is similarly rounded or tapered, so as to insure that the plugs will pass freely upwardly through the tubing string without hanging when elevated in the manner later to be described. As is obvious from the drawings, the plugs are maintained in engagement with the tapered seats by gravity and fluid pressure alone, the tapered surfaces of the plugs and seats being accurately ground and formed of non-corrosive materials so as to insure at all times tight, but non-sticking, joints between these elements.

In order to selectively control or meter theiiow of repressuring fluid through the ports 22 and 23, the lower tapered ends of plugs 29 and 30 are so designed as to overlap ports 22 and 23 and thereby reduce the eiective size of said ports, as desired. In this connection, it will be understood that, in order to enable the desired variations in flow, a plurality of port plugs is provided for use with each tting, the plugs of each set being identical in construction except that the tapered lower ends thereof are of varying lengths so as to cover more or less of the port with which they are adapted to be used. The vertical bores 32 and 33 of all plugs belonging to the Same sets as plugs 23 and 30 are suficiently large to offer until the pressure within the tubing string equalizes and the plugs drop into position on their respective seatsv by gravity. This replacement of the plugs may be done either all at one time or one by one. Should the Velocity of the dropping plugs become so great as to involve the possibility of injury to their lower tapered ends or the seats 26, 2l and 28, this velocity may be reduced by manipulating release valve 38 so as to produce a oounterflow upwardly through the tubing string which will check the fall of the plugs and permit them to be seated as lightly as desired. As is above pointed out, the maximum outside diameter of each plug is made smaller than the minimum internal diameters of the tapered seats of all of the fittings positioned above that with which said plug is adapted to cooperate, so that the plugs will pass freely through the tubing string to and from their proper seats. When the plugs reach their seats, release valve 3@ is tightly closed and the repressuring operation continued by opening inlet valve 36.

When it is desired to regulate or meter the ilow into the various producing strata of the well, the following procedure may be followed. After first installing a suitable meter in the inlet line 35, a port plug 3i having a vertical bore 34 of selected size, and plugs 29 and 30 having lower tapered ends of sufilcient lengths to completely close ports 22 and 28, are dropped into place on their respective seats in the tubing string I2. When inlet valve 36 is then opened, all of the repressuring fluid ows downwardly to the lowermost fitting and outwardly through port 24 into the associated productive stratum i5, thus giving a direct indication on the meter at the well head of the Velocity of iiow of the fluid into this stratum. If the plug 8| selected does not produce the desired rate of iiow, it is a simple matter to bring all of the plugs to the surface, substitute another plug 3l of diierent size bore, and repeat the metering operation until the plug of proper size is identified. The ow into the next higher stratum It is then regulated in like manner, again using a plug 29 on seat 26 which completely closes port 22 but retaining the plug 3i which was found to provide the desired iiow into the lowermost stratum i5. After the iiow into the middle stratum id has been properly regulated, the procedure is again performed with respect to the uppermost stratum I3, this time using for both of plugs and 3i those which have been identied as giving the desired rates of iiow through their associated ports 23 and 24.

It will be obvious thatI the apparatus just de scribed is also capable of use in such a manner as to enable measurement of the relative permeabilities of the different producing strata. For this purpose,'plugs eiecting complete closure of their associated ports are used for the ttings or all strata except that of which the permeability is to be measured, the tting corresponding to the latter stratum being provided with a plug of any de.. sired dow restricting characteristics and a direct measurement being made of the amount of uid which it is necessary to owinto the main tubing string in a given period of time in order to maintain the pressure in the tubing string constant at the well head.

In Figs. 3 and 4 there is disclosed another embodiment of the method vand apparatus of the present invention which is particularly adapted for use in controlling theow oi oil and gas from a producing well, but which embodies the same fundamental structure and mode of operation as the embodiment of Figs. 1 and 2. For simplicity, the following description will be limited to the use of the invention in connection with an oil producing well of the character wherein the oil is produced by gas lift, although it will be obvious that the same method and apparatus is equally well adapted to gas well operation. In oil wells 0f this type. it has been found that the flow of oil may be substantially accelerated if the main tubing string is provided with a plurality of ports at dierent levels through which may enter the gas which collects in the Well above the oil. As the ow from the well progresses and theuid column in the well is lowered, less energy is required from the gas entering the ports in order to lift the oil. Accordingly, it is desirable to provide means for reducing the effective sizes of the ports, or completely closing them, as desired, dining the operation of the well. The present invention is particularly well adapted for this latter purpose.

In the form illustrated, the main tubing string dil is paralleled by an auxiliary string it which is provided at its upper end with control valves 31 and 3S, inlet line 3a and valve 3e, and cushioning cage 39 similarly to the tubing string l2 of the embodiment of Figs. 1 and 2. The main tubing string lil of this second form of the invention, however, ls closed at its upper end by a blank sealing disk s2, and is provided with a. take-ofi line 48 and a valve 44 for controlling the ow of oil out of the main tubing string into said line, the latter constituting the eld line into which is delivered the oil recovered from the well.

As shown, the main tubing string I0 extends downwardly in the well 45 all the Way to the shot hole s6 in the lowermost producing stratum l 5 of the sand while the auxiliary string may terminate a suitable distance above the shot hole, there being interposed in the tubing strings at predetermined, vertically spaced locations a plurality of ported iittings 4l. i8 and 49 which are adapted to control the ilow of gas from the well into the main tubing string it in order to assist in lifting the oil from the shot hole whence it enters the main tubing string Q@ through the perforated lower end of the latter. These ported fittings are preferably detachably secured to the tubing strings by threaded connections, as shown, and a suitable packer titi is provided at or above the position of the uppermost fitting si for sealing oi the producing stratum or strata from the upper portion of the well.

The iittings il and d@ are of similar construction, each being adapted for connection into the tubing intermediate the ends thereof, and are respectively provided with chambers 5i and E2 of the same internal diameter as, and coaxial with, the main tubing string lit, and chambers 53 and 513 coaxial with auxiiiary string di and of the same interior diameter as the latter except for the restrictions introduced therein by the tapered seat members 55 and 56 which are adapted to receive and Support plugs 5i and te, respectively. Fittings dl and it are also provided with ports 59 and 6@ connecting the chambers lit and 52 with chambers E3 and 54, respectively, and with secondary parts tt and 62 coaxial with and of the same diameters as ports 53 and 5, and passing through the outer walls of said fittings so as to provide communication between the linterior of the well 45 and the chambers 53 and 54. Each of ports 59 and 80 and its associated secondary port Aextend horizontally and intersect the tapered surthe tubing in other ways than by the threaded connections shown. Similarly, the Yparticular arrangement of valves and connections at the well head which enable the port plugs to be raised by uid pressure alone may be varied somewhat from the embodiment illustrated. it should also be clearly understood th'at it is not necessary that plugs beused with all of the ported fittings at all times, since, when unrestricted flow through any particular port or ports is desired, that fitting may be used without a plug without in any way interfering with the herein described method by which whatever plugs are used may be raised and lowered from and to their respective seats.

Various other changes, which will now suggest themselves to those skilled in the art, may be made in the procedural steps of the method, and in the form, details of construction and arrange,- ment of the parts of the apparatus, without departing from the spirit of the invention. Reference is therefore to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In gas or oil well apparatus of the character described, the combination of a string oi7 tubing through which iiuid may be injected into or removed from the Well, means connected to said tubing at a plurality of vertically spaced points below the surface of the ground providing ports of xed size through winch uid may Dass from or to the interior of said tubing, means including plug members associated withA said ports for restricting the flow of fluid through the latter, and means for producing an upward ow of uid from said well of sucient force to raise said plug members from their ow restricting positions to the well head by uid pressure alone.

2. In gas or oil well apparatus of the character described, the combination of a. string of tubing through which fluid may be injected into or removed from the well, means connected to said tubing at a plurality of vertically spaced points below the surface of the ground providing ports of nxed size through which fluid may pass from or to the interior of said tubing, a tapered seat associated with each of said ports, a plug having a tapered lower end adapted to engage each of said seats and to obstruct the ow of Huid through the associated port, the maximum external diameter of each of said plugs being less than the minimum internal diameter of each oi' said tapered seats above that with which said plug is adapted to cooperate, and means for prdducing an upward flow of uid from said well of suiilcient force to unseat said plugs and raise them to the well `head by uid pressure alone.

3. In gas or oil well apparatus of the character described, the combination of a single string of tubing having therein a plurality of vertically spaced ports of xed size through which fluid may be injected into or removed from the well at a plurality of different levels, and means for con1 trolling the iiow of fluid through said ports comprising a tapered seat associated with each of said ports and a plurality of plug members having tapered lower ends adapted to engage said seats, said plug members being `so constructed and arranged as to offer resistance to the flow of iiuid through said ports when in engagement with said seats, the minimum internal diameters of said seats decreasing in order toward the bottom of the tubing string and each of said plug members having a maximum external diameter which is smaller than the minimum internal diameter of mamas each of vthe seats located above that with which said plug member is adapted to cooperate.

t. The combination according to claim 3 wherein said tapered seats are coaxial with the tubing, string and each of said plug members has an axial bore therethrough of a diameter which is smaller than the minimum internal diameter of the tapered seat with which it is adapted to cooperate. v

5.-A The combination. according to claim 3 wherein said tapered seats are coaxial with the tubing string and each of said plug members has an 'axial bore therethrough of a diameter which is smaller than the minimum internal diameter of the tapered seat with which it is adapted to cooperate, and including means for producing a ow of uid upwardly through said tubing string of suicient force to raise said plug members from their seats to the upper end of said tubing by fluid pressure alone.

6. The combination according to claim 3 wherein said tapered seats are coaxial with the tubing string and each of said plug members has an axial bore therethrough of a diameter which is smallerthan the minimum internal diameter of the tapered seat with which it is adapted to cooperate,'the bore of each plug member except that adapted to cooperate with the lowermost seat in the tubing string being suiiciently large to oier no substantial resistance to the ow of fluid downwardly to those ports which are located below that withl which said adapted to cooperate.

7. The combination according to claim 3 wherein said tapered seats are coaxial with the tubing string and each of said plug members has an axial bore therethrough of a diameter which is smaller than the minimum internal diameter of the tapered seat with which it is adapted to cooperate, the lowermost port in said tubing string'being located below its associated tapered seatand having a greater cross sectional area than the bore of the plug member adapted to cooperate with said seat, whereby the flow through said port is controlled by the size of the bore in said plug member, each of the other ports in said string intersecting the tapered inner surface of the associated seat i-n such position as to be obstructed by the tapered lower end of the plug cooperating with the latter.

8. In gas or oil well apparatus of the character described, the combination of a single main string of tubing having therein a plurality ofvvertically spaced ports oi iixed size through which uid may iow into or out of said tubing at a plurality of dierent levels, and means for controlling the flow of uid through said ports comprising an auxiliary string of tubing paralleling said main string-and into which said ports lead, a tapered seat formed in said auxiliary tubing string adjacent each of said ports, a secondary port associated with each of said seats providing communication between said auxiliary tubing string and the well, and a plurality oi' plug members having tapered lower ends adapted to engage said seats and to obstruct the iow of iiuid through said first named ports, the minimum internal diameters .of said seats decreasing in order toward the bottom of the auxiliary tubing string and each of said plug members having a maximum external diameter which is smaller than the minimum internal diameter of each of the seats located above that with which said plug member is adapted to cooperate.

9. The Combination accordi-ng to claim 8 in-l plug member is' cluding means for producing a flow of fluid upwardly through said auxiliary tubing of sufiicient force to raise said plug members from their flow obstructing positions to the upper end of said auxiliary tubing string by fluid pressure alone.

lil. The combination according to claim 8 wherein at least the lowermost one of said plug members is imperforate longitudinally and the lowerrnost secondary port in said auxiliary tubing string is positioned below its associated tapered seat in such position that the bottom end of said lcwermost plug member may always be subjected to the fluid pressure existing in the well adjacent said secondary port. l

il. lin gas or oil well apparatus of the character described, the combination of a string of tubing through which uid may be injected into or removed from the well, a fitting connected to said tubing forming a tapered seat therein and having a port intersecting the tapered surface of said seat through which fluid may pass from or to the interior of said tubing, and a plug having a tapered lower end adapted to engage said seat and to obstruct at least a portion of said port so as to restrict the iiow of iiuid therethrough, said plug also having a vertical bore therethrough ofsmaller diameter than the minimum internal diameter of said tapered seat.

l2. lin gas or oil well apparatus of the character described, the combination of a main string or tubing through which fluid may be injected into or removed from the well, an auxiliary tubing string associated with said main string, means connected to said tubing strings at a point a substantiail distance below the well head forming a tapered seat in said auxiliary string and providing a port intersecting the tapered surface of said seat through which fluid may pass between the interiors of said main and auxiliary strings, a secondary port associated with said seat.. providing communication between said auxiliary string and the well, and a longitudinally imperforate plug member having a tapered lower end adapted to engage said seat and to obstruct at least a portion of said iirst named port so as to restrict the iiow of fluid therethrough.

13. In a pressure well, the combination of a single string of tubing through which a repressuring fluid may be injected into the well, a connection to the upper end of said string for supplying repressuring fluid thereto, a plurality of fittings connected to said string at vertically spaced points below the well head each having a port through which the repressuring fluid may iiow from said string into the well, means for selectivelyregulating the flow of fluid through said ports including a removable plug member associated with each of said ports and at least partially restricting the flow therethrough, and means for producing a back flow of iiuid from the well into and upwardly through said tubing string of sufficient force to raise said plug members from their flow restricting positionsto the well head by iluid pressure alone.

14. In a producing well, the combination of a main string of tubing through which the iluid to be recovered from the well may be raised to the well head, an auxiliary tubing string associated with said main string and having a plurality of vertically spaced openings in the wall thereof through which fluid may iiow from the well, means providing communication between the interiors of said main and auxiliary strings including a port positioned at substantially the same level as each of said openings in the auxiliary string, means including a removable plug member associated with each of said ports for restricting the flow ci' fluid through the latter, and means for producing a flow of fluid upwardly through said auxiliary string of suicient force to raise said plug members from their flow restricting positions to the top of said auxiliary string by fluid pressure alone.

HARVEY T. DORTON.

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