US2481422A - Means for spotting a fluid in a well - Google Patents

Description

Sept. 6, 1949. J. D. HAYNES ET AL 2,481,422

MEANS FOR SPOTTING A FLUID IN A WELL Filed June 14, 1945 l 4 Sheets-Sheet 1 i I W 5 2 i 4 INVENTORS James D. Haynes BY or/m w Lyons ATTORNEYS fiept 6, 1949.

Filed June 14, 1945 ililllili Elililil IHHEI ANS J. D. HAYNES ET AL EIIIEHHHHIH ill! FOR SPOTTING A FLUID IN A WELL 4 Sheets-Sheet 2 INVENTORS James O Haynes y Or/l'r) 14/. Ago/IS A TTOR/VEYS J. D. HAYNES ET AL.

MEANS FOR SPOTTING A FLUID IN A WELL Sept. 6, 1949.

4 Sheets-Sheet 5 Filed Jun 14, 1945 l rilllr'li'l'lffllill /re I N V EN TORS \farn 65 0. Ha Or/ in 14 Lyons Y B E M A TTORNE Y5 Sept. 6, 1949. J. D. HAYNES ET AL MEANS FOR SPOTTING A FLUID IN A WELL Filed June 14, 1945 4 Sheets-Sheet 4 h m n v ggJf i p A i g.

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I N V EN TORS mm WUO Q 0. W

Jo Y B A TTO/QNEYS Patented Sept. 6, 1949 MEANS FOR SPOTTING A FLUID IN A WELL James D. Haynes, Kilgore, Tex., and Orlin W. Lyons, Shreveport, La., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Application June 14, 1945, Serial No. 599,450

Claims.

The invention relates to delivering a fluid to a selected elevation in a deep well. It more particularly concerns means for delivering a liquid or fluid material to a prearranged elevation or zone in a deep well through a tubing string.

In the construction and operation of deep wells, it is oftentimes desirable or necessary to deliver a charge of fluid material of one kind or another to a specific elevation in a well bore, as for example, that of the producing formation when it is to be treated with an acid solution.

The operation of deliverin a liquid or fluid to a specific elevation in a well bore is generally referred to as spotting. Spotting of liquid materials is usually attempted through the tubing and the liquid or fluid involved may be delivered from the tubing into either the uncased or cased well bore, in the latter case usually opposite perforations in the casing.

Several disadvantages inure to such practice among which are that there is no satisfactory way of determining just when the fluid, which is to be delivered from the tubing into the well, begins to emerge from the tubing, when the delivery is complete, and the exact amount of fluid delivered. Without this knowledge, accurate control of the level or elevation of the delivered liquid outside the tubing is diificult, if not impossible, to achieve. A part of the difficulty arises from the nature of the tubing in that its volume is not precisely predictable under the conditions of use due to variations in its distention under pressure, variations in the amount of space at the tubing collars or joints, and various dimensional inaccuracies in the tubing itself. In addition, the volume of fluid retained, if any, in the tubing is not predictable. Another factor militating against accurate spotting, through the tubing, is occasioned by the mixing which inevitably occurs at the interface between the fluid to be spotted and the displacing fluid which follows it. When the volume of fluid to be delivered is relatively small many of these difliculties are accentuated. For example, in the application of resin-forming liquids to sealing and plugging operations in well bores, as described in U. S. Patent 2,274,297, cases arise in which it is highly desirable to deliver a small but precisely known amount of resin-forming liquid at a specific elevation in a well bore, as in sealing a zone of water infiltration adjacent to an oil zone without sealing the latter, plugging back a short section of the well hole, and forming a seal behind the casing through perforations. In carrying out such operations, the success of the work is largely determined by the accuracy with which a precisely known volume of cementing liquid can be spotted in the well. In any event, in so far as we are aware, there is no commercially available apparatus for use in overcoming the various difficulties inherent in conventional spotting devices and methods.

The principal object of the invention is to provide an improved means for spotting a fluid in a well. Other objects and advantages will appear as the description proceeds.

In brief, in practicing our invention, the fluid to be spotted is delivered to the prearranged zone in the well bore through a conventional tubing string to which has been fitted one or more special cylindrical constrictional elements of bores which are in axial alignment with that of the tubing string and have a, cross-sectional area of at least 20 per cent less than that of the tubing. We employ in conjunction with the foregoing devices one or more highly resilient pistonlike plugs having a diameter slightly larger than the bore of the tubing so as to form a fluid seal with the wall of the tube when inserted therein and are able to slide in the bore of the tubing when under moderate differential pressure but can be expelled through the aforesaid constrictions only under differential pressures substantially much greater than that required to bring about their longitudinal movement through any other portion of the apparatus. In some instances, the annular space between the outside of the tubing and the well bore may be packed off either at, above, or below the cylindrical constrictions so as to prevent the fluid material delivered into the well through the tubing rising above a designated elevation. Spotting may be accomplished by positioning the discharge end of the tubing apparatus at the desired elevation in the well; introducing the charge of fluid material to be injected into the Well into the tubing string, a piston-like resilient plug having been inserted in the tubing in front of the charge, so that the plug is caused to move down the tubin in pistonlike fashion as the charge moves down the tubing; inserting behind the charge a second pistonlike resilient plug; and then forcing the charge and the resilient plugs in the proper sequence through the. constrictions into the well by the application of fluid pressure behind the last resilient plug. By the foregoing method, thus briefly outlined, complete purging of the tubing string of the fluid to be introduced into the well is obtained, the amount and position of the fluid so delivered to the well is precisely determined so that spotting is accurately and efiiciently accomplished.

The invention is further exemplified in the following description and illustrated in the accompanying drawings, in which-- Fig. 1 illustrates in vertical section the upper portion of a well suitably equipped? for carrying out the invention and disclosing a-resilient pistonplug in position in the lock chamber in readiness to be driven into the well ahead of a fluid material' to be spotted. V

Fig. 2 illustrates in vertical section the lower portion of the well of Fig. 1 andi'discloses the combination of. a tubing string and cylindrical constrictional element attached theretb'; the-dis charge end being in position for spotting a liquid tinuous unobstructed tubular bore (when valve" '9 is open) connecting the lock chamber with the tubing. string. The; top of the lock chamber is provided with a removable closure plug l5 and lateral pipe. connection 16 leading to the valve I1 opposite a specific zone traversed;bythewelllborea Fig. 3 is an enlarged view partly in central vertical section of a form of resilient piston-like plug adapted to make at -sliding fit with the bore ofi thevmbing astrmg. 1

FigL l 'is a similar viewto Fig; 2-and'shows a oharge ofa'fluid material to=be spotted located betweem two resilient piston-like plugs,- the charge having been driven to: the-bottom of the tubing. by'apressuring fluid. r

Fig. 5 is a similar view to Fig. 4 and' showsa further stage inmovement-of the resilient plugs and -cliarge of fluid material;

Figifi is asimiiar view to Fig. 4 and showsthe completion of the delivery of fluidmaterial into tne well Fig.1? isa; similar view tic-the lower portion of Fig: zf'sh'owi'ng a modification'of the apparatus of E igz z and includes a packer on the tubing above the cylindrical constrictional element; 7

Fig. 8 is asimilar view to thelower portion of" the well 'of'Fig; 2" and shows a-modifi'cation or the apparatus of Fig. '2, includinga packer below amodified f orm of a cylindrical constriction'al element, themcdiiiedi element permittin 'itto f'unctio'm as aeback-pressure valve" in" combinati-on with a-hesilientpiston4ike pl ug shown in position to close th'e'va'lvez V I ii-illustrates a preferred jorm of-"the appa ratiisand-sh'ows invertical section a pair of cylindr icalconstrictional elements, the upper one being: a back-pressure valve, joined by a tubular section adapted to accommodate resilient piston;- likeplugs:

Figs.- '10 tfo-l l, inclusive; are-each similar views inzvertical:sectionof a perforated portionor thec'ementedcasin'g' of the wellofFi'gi '2, the-perforations== being opposite a zone tobe sealed with a flmd'agent'andshows the-sequence of operations of spotting: the sealing agent in 'the =zoneusi'ng the appamatus illustrated in:Fig. 9 in=cor'nbina'titznrwith aitubingstring;

Referring more particularly to the drawings; wherei'mlike reference numerals designate similar" pants-am each of: the-figures; the well 'in: which the apparatus and method may beused -may be-cased inzipart', asillustrated, and the bore traverse-one on'rn'ore g'eologicalistrataor zones; provision being made :for suitable;accessories attaclied to th e we'll above :grbundilevel for facilitating the-practice or; the invention, as 'shownin Fig.51i In -this view, thez'well' b'ore'. I iSi-diilld into the eanth 2 and providedwith' a l casing 3' cement-Jedi in place with cementilz Attached toathe topoftlfi casing -i's az oasingheadfi having valved'iconnections t and 3 respectively, leading :to the.- interior of theecasing'; lnstringroftubing. 8' issuspendedlfmom'sthacasinga Bead: and projects: above it, the upper. 'end beingi Wfilfii turn is-' connected to one side of the T it, theoppositesid being connected to the valve I3; The" T P8 is provided with the valved connection. liawhichimay lead to pumps, truck tanks, or like equipment, not shown, for supplying treatingfiui'd's, pressuring fluids, cementing materials, etc., as may be required' accordingto the treatm'erit tc bemade;- Eressure gauge 2E communica ifes with-the interior-of tlie lcck chamber l registering pressure therein applied to thatubing string: V

ln tiie embodiment shown in Figs 2; 4, 5 arid-'6; the lower portiom of the well: bore is cased to -the casing seat; 2-ileavingth'e 'une'a se'd portion: 2 2 into whi'c the tubing: string 8 extends. Tourserk terna lly threaded end 23 of me tubing string screw threaded a tubular section'- comprising the bore constrictional element Ma This element comprises a tubular body portion lfi havihg a -reduced? diameter cyunancar bore ilii", its cross sectionalarea being between alci'out 25 -ari'd percent less than-thatoftlie tub n string. The; preferred cross sectional area isabOut-GOper'ceIit less than that of the bore of. the tubing string; Thelengthpi -thereduced diameteriore-is at least? 3 and need not exceed 10 times its-diameter. The upper-end of the-reduced diameter cylindrica hbore Z6 is enlarged to form' the mouth orfunnei sec tion 21 withsides-slbping at about 6'6 tothe axis of the'bore and an in ternally threaded section 23 adapted to engagetheexternallythreaded end-" 23 of 'tlie'tubin'g string; The funnel shaped section- 21 l provides a gradual" reduction indi'ameter from that'of theboreof the-tubing"to'tiiat=of the re duc'ed diameter cylindrical bore 2%. The discharge: end 2 9'- of the cylindrical bore is=shownf positioned-'- opposite azone 30* in which a ffuid -is tic-bespotted.

suitable form of resilient pist'on-lili'e'- plug; whiclris-illustrate'd-in'fig: 3; comprises a ma-ssof natural: or synthetic rubber; preferably rice-- 1 preney or like resilient or yijeldablematerial generally cylindrical form; the-Iengthbeing about 3 't'o 8'or preferably 6 times its diameter; The

central portion- 331's preferably solid resilient or yieldable material The ends are oountersanilr thereby providing the recesses and '3i ajnd forming annular lips 3fi and '3 l respectively. dercuii annula-rgrooves 33 and W provide-the up" wardlyd'irected lip '40' and the downwarz'i1y; Clifrecte'd lips4 respectively. The diameter of the plug is substantially the. same; or preferably slightly larg'er thamthe-irrternal diameter of -"the tubing string-inwhich the plug to travel sales to make: a sllding sealing: lit. with the: tube wallt' 'Bhe apparatus of- Figs. 2, 1, 5gand6 may ybe modified by including apacker 12- on the end -of the tubingstr ing fli as shown in- Fig: 7 ne sonstricttoiral elem'en't"- being joined; to= the; acker by'the nipple lifwhichwmay beof driliablelpipe':

such asia m'agne'siiim onaluminum alloye In his vainedzzwith the-gate; valve 9 so. assta provide a w arrangementa 'tlierei isz-a continuous unrestricted bore from the tubing string through the central bore 46 of the packer to the element 44.

The single constrictional element, shown in Fig. 8, and indicated generally by numeral 41, is similar in construction to the constrictional elements illustrated in the preceding figures in that the cross-sectional area and ratio of length to diameter of its constricted bore are as specified for the previously described bore constrictional element. It has the added features of a recessed lower end comprising an internally threaded portion 48 and a valve seat portion 4Q. As shown, the Valve seat has the form of the lower portion of an inverted cone, the base portion 58 having the same diameter as that of the bore of the tubing string 8 to which the device is attached, and seat portion 49 a slope corresponding to the flared portion 38 of a resilient plug. A satisfactory slope is one making an angle of with the axis of the bore of the constrictional element. The base 50 of the conical portion coincides with the cylindrical ring portion 52. As shown, the constrictional element ii is arranged below and screw threaded to the tubing string 8 just above and in combination with a packer 53 to which the element is joined by the tubular section 54 having an upper externally threaded end 55 engaging the internally threaded portion 48 and a lower externally threaded end 56 engaging the internally threaded coupling member 5! on the upper end of the packer 53 which may be of any conven-- tional form suitable to seal the annular space in the well. The interior of the packer is provided with a continuous tubular passage 58 having a bore of the same diameter as that of the tubing string. The tubular section 54 is made of sufficient length to accommodate from one to three or four resilient plugs within its bore. A tail pipe 59 is screw threaded to the lower coupling 60.

In Fig. 9, a pair of bore constricting elements, instead of a single constrictional element, is provided, which may be used, in combination with a tubing string. The upper constrictional element 83 is similar to that shown in Fig. 8, its lower end 64 being screw threaded to the upper end of the tubular section 66. This tubular section is made of sufficient length to accommodate at least one or two resilient plugs and is preferably about 4 times the length of a plug. The lower end 61 of the tubular section is screw threaded to the internally threaded upper end 63 of the lower bore constricting element 69, this lower constrictional element being of the same form as that of Fig. 2.

In Figs. 10 to 14, inclusive, a portion of the cemented casing 3 in the well bore is shown having a series of perforations H opposite a zon 2 to be treated, the upper portion of the Well being equipped as in Fig. 1.

In practicing the method and in operating the various forms of the apparatus disclosed, the well is generally equipped above ground with the lock chamber apparatus shown in Fig. 1, connection being made at IQ for supplying the treating fluid and a pressuring fluid by means of which the treating fluid is to be driven into the well and spotted at a specific elevation as desired. The simple form of spotting device, illustrated in Fig. 2, in position in the well, may be attached to the tubing 8 before lowering it into the wall, the discharge end 29 being positioned at the elevation at which the treating fluid is to be delivered to the uncased portion of the well bore 22. It is usually desirable, if not necessary, to bridge the lower portion of the well hole as by filling the portion to be bridged preferably with a temporary filling or plugging material to the level above which spotting of a treating fluid is to be achieved so as to exclude the treating fluid from the well bore below the zone to be treated. One way of temporarily bridging the well hole with a filling material so that the bridge may be removed after use is described in a comp-anion application of Philip J. Lehnhard, Jr., Serial No. 594,727, filed May 19, 1945, now abandoned. According to this method, an especially graded granular material, specifically 20-80 mesh sand (referring to standard sieve sizes), is circulated into the well hole through tubing. After the sand has settled into position to form the column 3i, the ta er it is sealed with a cap 32 of a non-penetrating liquid mixture, such as drilling mud. .If desired, other bridges may be used.

After plugging back the well, when necessary, to the desired elevation and positioning the tubing and appended apparatus as in Fig. 2, so that the lower end of the tubing is adjacent the zone to be treated, spotting a fluid agent therein is carried out as follows: A first resilient pistonlike plug, such as one of the form illustrated in Fig. 3, is placed with lip 31 downward in the lock chamber 54 opened by removing closure plug 15. During this operation, valves 9 and I9 are closed and [2 opened so that fluid in the chamber, displaced by the plug, can escape from the chamber. After placing in the chamber I4 the first plug so that it occupies a position between the cross I l and the connection of valve I3, as indicated by 83, valves 52 and 13 are closed, and valves 9, H, and iii are opened. The charge of fluid material to be spotted in the well is then introduced into the tubing 8 by pumping it into the lock chamber above the first plug through the valved connection 19. The volume of the charge material to be spotted is determined in advance according to the needs of the well and may be measured accurately before introduction so that the volume delivered to the well may be thus known accurately. The pressure required at the head of the liquid column above the plug, to cause the charge and lower plug to descend in the tubing 8, is observed on the pressure gauge 28. After the charge is introduced gate valves 9 and connection l9 are closed, the closure plug l5 removed, and a second or top resilient plug is inserted in the lock chamber in the same manner as the first plug while allowing the fluid it displaces to be drained from the chamber through valve it. The closure plug !5 is then replaced and valve l2 closed. Valvecl connections I3 and t9 and gate valve 9 are opened, thereby making the apparatus ready for driving the liquid charge between their upper and lower subtending plugs into the well.

This is accomplished by introducing a pressuring fluid, such as oil or water, through connection l9 under suitable pressure into the tubing 8, thereby driving the charge and the upper and lower plugs along the tubing 8 until the lower plug reaches the constrictional element 24, as shown in Fig. 4.

During the introduction of driving or pressuring fluid 84, the pressure exerted on it by the pumping means (not shown) is observed on gauge 2e. thereby indicating the location of the plugs in the tubing. Normally at first, there is only a small or even a negativedriving pressure depending upon the extent to which the hydrostatic head of the entire liquid column in the tubing is counterbalanced by that, if any, outside the tubing and the frictional drag of the plugs, and this pressure may remain relatively low or increase regularly as the plug descends in the tubing string until the first or lower plug proceeds to the point where the lip 31 abuts the funnel section 21, as shown at 83A; It is to be understood "that the bore of the tubing string is substantially uniform and unobstructed from end to end so convenient manner as by threaded collars. When the lower plug thus reaches the constrictional element 24, there is an abrupt rise in pressure which registers on gauge 20 and this rise in pressure indicates that the fluid charge 85 and the lower plug ahead of it is in position to begin its delivery into the well bore l The pressure applied to the driving fluid B is'then increased sufliciently to drive the lower plug from its position at 83A into and through the constricting throat or bore 26. As illustrative of the increased pressure to be surmounted, a resilient plug consisting of a 2-inch diameter grooved cylinder, 6 inches long, of neoprene with countersunk ends requires a difierential pressure of 1000 to 1800 pounds per square inch for forcing it through a constrictional element having a cylindrical bore '7' inches long and 1.187 inches in diameter. As the lower plug is driven into the constrictional bore, it contracts in diameter and elongates in conformity with the bore 26 and on emerging again expands, as shown in Fig. 5, where the lower half 86 has emerged from the constricted bore .while the upper half 81 is'shown in the compressed state, On being expelled from the constricted bore 26, the lower plug drops into the 'well hole asat 83B and the pressure gauge 20 shows a decreased reading corrresponding to the decline in pressure required to force the lower plug through the constricted bore 26, thereby in- 'dicating that the liquid charge 85 has begun to enter the well bore, the decline in pressure is generally of the same order of magnitude (1000-1800 pounds per square inch) as the differential pressure required to drive 'in 'plug through the constricted bore. The position of the upper plug in the tubing depends upon the volume of the chargefand that of the bore of the tubing. Large charges cannot always be introduced into the tubing before the first plug is driven into the well hole. The usual charge is generally smaller than the volume of the tubing so that both plugs may be present in the tubing "at one time as shown in Fi 4.

As the charge 85 enters the well bore, the top plug continues to descend under the force of the driving fluid column 84 until the upper plug comes varies mainly with the volume of the charge and that of the hole, the porosity of the surrounding earth, and the rock pressure.

Similar procedure is followed in those instances After the injection into the zone of a fluid agent.

'70 89. The depth attained by it in the well hole where the liquid or fluid charge introduced into the well is to be confined below a predetermined elevation as by including in combination with'the tubing string a packer. 'This procedure may be followed in the well already described usin such an apparatus as illustrated in Fig. '7, in which the eonstrictional element 44 and packer 42 are attached to the end of tubing string 8 of the well of Fig. 1, thereby forming a complete assembly using a short length of tubing 45 to join the packer with the constrictional element 44. The assembly is lowered into the well bore l as before until the packer 42'is at the top of the zone 30 at which a fluid charge is to be spotted and then the packer is set against the wall of the well hole, as shown, so as to preventliquid introduced into the well from rising in the bore above the zone, the hole below the bottom'oi the zone being bridged as described. The delivery of a charge of treating agent into the well is accomplished in the same manner as that already described with theapparatus of Figs. 1, 2, 4, 5, and 6. This procedure and apparatus provided enables a charge of a fluid agent to be directed without significant loss of volume through the tubing into a specific zone 36 of the well hole lying between the upper elevation 00, just below the packer .42, and the lower elevation adjacent to the top 32 of the bridge 3|.

the packer may be released and the apparatus withdrawn from the well, as desired. If the fluid agent used prevents the withdrawal of the constrictional element, as' when acementingag'ent is used, the tail pipe portion Q5 may be madeof drillable metal so that it may be drilled up after disconnecting the packer from it- If desired, a modified form of constrictional element, as shown at 41 in Fig. 8, may be placed between the end of the tubing string 8 and a packer 53 using a short length of tubing 54 to join them, thereby obtainin all the advantages of the arrangement of Fig. 7 and the further advantage of aback-pressure valve which may be closed'with the last resilient plug, thereby preventing the charge or other fluid returning once the plug is seated against the valve. In using this form of the apparatus, the procedure is generally the'same as that already described, the assembled apparatus being lowered into the well so that the packer 53.may be set at the top 90 of the zone 30 to be treated, the tail pipe 59 extending into the well hole'below the packer. The head of the well maybe equipped as in Fig. 1 and the apparatus,

ahead of it down the tubing. When all the charge a has been introduced, a second resilient plug is inserted and then a pressuring fluid, such as oil or water, is introduced so as to drive the charge into the well hole. When the first plug arrives at the bore constricting element 4 an abrupt increase in pressure of from about 1000 to 1800 pounds per square inch is observed on'gauge 20. Pumping or the application of pressure to the driving fluid is continued so as to drive the first plug through the constriction 41, tube 54, packer 53, and tail pipe 59 into the bore I below the packer. After II the first plug is was driven out of the tail pipe, it drops into the well hole, as indicated by numeral 92, and the pressure reading declines abruptly indicating this result. After the first plug is thus driven into the Well hole, introduction of pressuring fluid is continued, thereby delivering the charge of fluid agent into the well. The charge fills the space between the bottom 93 of the packer and the top 32 of the bridging plu 3| and if the volume of the charge exceeds that of the space the balance may be pumped into the zone 30. The pressure indicated on the gauge 2?! is observed during the introduction of pressuring fluid and when an abrupt rise of as much as 1000 to 1800 pounds per square inch, more or less occurs, it indicates that the second plug has arrived at the constriction 41 and the charge is fully expelled from the tubing. Sufficient pressuring fluid is then introduced to just drive the second plug through the constriction 41 but not into the well hole, thus allowing the second plug to remain in the tubular section 54 below the valve seat 49 as indicated at 93. In this position, the upper lip 96 of the'plllg abuts against the conical shoulder 49 which prevents the plu from being pushed upward into the constricted bore of 41 by fluid pressure acting on the lower end of the plug. Thereby, the plug acts as a back-pressure valve-closure for the tubing so that maintenance of pressure on the pressuring fluid in the tubing is unnecessary after the charge is expelled. After the charge has done its work, the packer may be released and the apparatus withdrawn.

If the fluid charge delivered into the well hole through the apparatus is a cement, the release of the packer is not always possible. However, since the cement, if used, is completely expelled from the tubing string to a point below the upper plug when in the position 93, it is customary to disconnect the nipple 54 from element 57, pull the tubing out of the Well, and then drill out the packer.

The apparatus of Fig. is especially adapted for spotting cementitious fluids, particularly of the type which by chemical change, such as polymerization or condensation, become resinous solids. Liquid compositions of this type are now well known and their use exemplified in the aforementioned U. S. Patent 2,274,297. A typical application of the apparatus is its use in spotting a sealing agent behind perforated casing as depicted in Figs. to 14, inclusive, wherein'a specific zone 12, as for example one containing water, behind the cemented casing 3 isto be sealed by injecting into the zone a charge of a resin-forming liquid sealing agent through the perforations N. This is accomplished by equipping the head of the well with the apparatus of Fig. 1 and securing the upper end 52 of the assembly of Fig. 9 to the lower end of the tubing 8, the length of which has been chosen so that the discharge end 95 of the lower constrictional element 69 will be adjacent the lowermost perforations when lowered into the casing of the well, the hole below the perforations being bridged temporarily as previously described with the bridge 10. After lowering the tubing and appended apparatus, the casing head 5 is made fast to the casing 3 and the tubing 8 to the casing head. It is advantageous usually to wash the well clean of drilling mud, if any be present, by circulating water down the casing and up the tubing, as by introducing water through valved connection 6, valves 9 and [2 being open, I, l3, l1, and l9 being closed, circulation of water strictional element 69.

.is continued until the discharge from valve I2 runs clear, valved connection 6 then being closed. Plug I5 is removed and a first resilient plug inserted in the lock chamber l4 thereafter plug i5 is replaced and valve 52 closed. Valve H is opened and a measured quantity of sealing fluid, such as a partially condensed phenol-aldehyde mixture containing a catalyst for inducing further condensation to a hard resin when in the well formations, is introduced through the valved connection l9. Accurate measurement of the volume of sealing fluid used is best accomplished by means of a calibrated tank. After introducing a suitable amount, such as 5 to gallons, more or less, depending on the amount of sealing to be done, valve 9 is closed, i2 opened, plug I 5 removed, and a second resilient plug inserted in the lock chamber Hi. The plug lt'a is replaced, valve l2 closed, valves 5 and 9 opened, and a pressuring fluid, preferably one of lower specific gravity than the sealing fluid, such as water, is

introduced through the valved connection l9,

thereby driving the two resilient plugs and charge of sealing fluid subtended by them down the tubing string. Only a moderate pressure is usually required for this operation. During the descent of the plugs and charge fluid displaced thereby from the well is al1owed to escape from the casing through valve 6.

The arrival of the first plug at the upper constrictional element 63, as shown in Fig. 10 at 96, is signalled by an abrupt rise in pumping pressure on the pressuring fluid, as indicated on gauge 20, and the charge of sealing fluid then comprises the fluid column 9'. occupying the space below the second plug 98, the pressuring fluid 93 being shown above it. The pumping pressure is allowed to increase to the extent necessary to drive the lower resilient plug into the tubular section 66, as shown at Mill in Fig. 11, whereupon the pumping pressure abruptly decreases until the downward travel of the lower plug is again arrested by the lower constrictional element 69. The pressure signals thus produced by the passage of the first plug through the upper constrictional element 63 and its abutting against the lower constrictional element 69 signify that-the sealing fluid column 97 is at the bottom of the tubing imposition to begin its entry into the casing above the bridge 19.

The pumping pressure is then increased so as to expell the lower plug into the casing and the fluid charge, the complete expulsion of which is signalled by an abrupt rise followed by an abrupt fall of the pumping pressure as the second plug is driven into the tubular section 66 as shown in Fig. 12. The pressure then abruptly rises again as the upper plug abuts the lower con- The pressure is not permitted to increase sufficiently to expell the second plug; instead this plug is allowed to remain in the tubular section 66 to act as a back-pressure valve-closure preventing return of sealing fluid from the. easing into the tubing string.

During the delivery of the sealing fluid into the casing, a corresponding volume of displaced fluid is usually discharged from the casing head through valved connection 5. It is advantageous to measure this volume as it serves as a means of approximately computing how much of the sealing agent has entered the formation through the perforations H, as the volume of fluid discharged from the casing corresponds to the volume of the space ocupied in the casing by the sealing fluid. I

behind'thefluidlnaterial being' s V H V ,a back-pressure valve-closure by lbdg'ihgin the a a-ease the cas e i1liistfated, the 'sealih fluid is she wh te 'have risen in" the easing outside the tubing to a level 'l-fiil well above t lie perfdrations. "After discharging the -sealihg fluid into 'the cas- "ing,the tubing isrelevated so -that tlie "discharge I end 9531s raised above the 156p "ill l of the oluinn "ofsealingfiuid infthe 'casihg as'in li'ig. 13. 'The casinghead valve fi 'is then cIosedand pumping *of pressuring fluid throug h 'valve'd eam-anon i is is then continued so as 'to Xpll "the f la's't refisilient plug from the thbular section 66, 3 the extpu'lsion of this plu g 'being signalled -by area-tram j decrease in pumping pressure. -After e'z'qrielling 'j the last plug which drops into the war hole, 1 as 'show nin Fig. 'l4;pressuring 'fluid is introduced a pended constrictional' elements 'withdrawn froml th'ewell. Any sealing fluid set up i-n-the' casing 7 is removed as by" drilling v 7 I It will be understood that-while the use 'of' the apparatus and method of the inv'ention has been I described and illustrated largely as being applied f to different zones of the same'welL this'isnot to be construed as limitingthe invention either'to V such applications OIILt O wells having the-{Zones illustrated, as the invention-may be used-invarious types of'wells-whether cased or*nbtaridfirrespective of the number and kinds' of'zonestravversed by the well; bore.

' Furthermore; although in "the preferred {em- .bodiment of the invention its useis illustrated in spotting a sealing fluid, itwill'be understood that other treating fluids, such'as acidiz'ing stamens,-

e. g. "Er-25 per cent 'l' y 'drochloric' acid solutions, may be spotted similarly.

It will be apparent,- also; that the-'apparatus-of Fig. 9 may be used inconibinationwithfa packer or drillableretainer suchas a conventional cenient retainer, for example ,-a model fK cejm'ent retainer manufactured by Baker Oil Ifo0ls,Inc., the lower-end @5' being connected 'preferably'to the top of 'the' retainer, The bore throughthe mandrel of the retainer "should be substantially the same as that'of the tub'irig 'stri ngfso' that' "fluids and plugs driven through the tubing string "and constricted 'bores63 and" 59 havea *continu- ,ous unobstructed passage through 'the' retainer.

With such combination, it-is 'advantageo'us to "provide circulation" jars on the tubing 9' string above the retainer although the apparatus" may be usedwithout them. 7 V

v, The" apparatus "of Fig. "9 is "also -signilarly adapted for use with a conventional retractable retainer or packer in's'teadof drillable yang-ere or packers. The apparatus is assembled in'the tubing string either above "orbe1"o w the packer or retainer. If assembled" above the retainer: it

is advantageous to provide a sufficient lngthof tailpipe below the retainer to prevent "cementitious fluids delivered 'through the' apparjatusf'into the well'irom rising upward fin the bore'to "the retainer, thereby getting'intd"tl*ifslipsIahfl other working parts of the retain'en With "such. an arrangement, the @last "resilient pluglfifntro'diiced r 1 2 sectionbt, theupper elid czf theipliig abutting' th'e valve seat portion of the A constricted -bore Element -6-3. After the fiuid is spotted, the last plu g -m V applying 's'u'fiicient fiuid -pressure through the wen isf m-ai'nt'ain'ed until the material has "st. Tl' eh the retainer" is release'd and the-"apparatus withdrawn n-omthe' wen. We eia m: 1. 'n appar t' s for s'p'ottin'g afluidni'aterial ewe iselecte'd' Zonejin a well comprising the com- Y in'atidn of a jtuhingstring' havinga substann'di an upper tubular "membe havingfa'n unbstructeu Eyli'n'drical bore to per centless thehpperend "of'the s'aidiipp'er' tubular member eing secured to the ilowerendpf the tubing ring a tubular-section on the lower end of the l ng substantially the same bore as the "tubing string; a lower tubular member on g the lower end L of the tubulars'ect'ion, said lower tubumfmemher having "an unobstructed cylindrical "bore 25 to 70" per cent less "in'cross sect'io'nal area? than that "of theftubulansection, the combinationbe- '-'ing' adapted to be lowered into the I Well so: that :"the last mentioned tubular member "is opposite the-selected'zone. e

V 2. An ap aratus v a selected zone in'a well omprising the combination of atubing' string having'a'subs'tantiallyluni Y form -uni'ibstructe'd' hore' from end" to end a first tubular member having anunobstructed cy'lindrie cal bore 25 120 70 'per cent less in'cross-sectional j-areaithan that of the tubing string, the upperend of said first tubular memberbeingsecured' tothe lowerrend of the tubing string; atubular section "on the lower end of the first tubular'memb'er said V f tubular section having substantially the same bore as the tubing string; a'second tubular mem-f sectional area than that of the tubular section, V

the lower end of'the-boreof-theffirst tubular member having a recess forming-a valve seat whereby V a resilient piston-like plug-lodged in the tubular "wardly'against the seat, the combination being a section formsa closure therefor whenurge'd upadapted'to be'lowered i'nto' the well so that the second tubularmember is-opposite the selected 'zone. a I m 3. An apparatus for spotting a fluid material in'a'Well adapted for'useon the lower end'ofa' 'string Oftllbihg having an unobstructed bore from end to end. comprising a pair of sho rt*tubularj I 7 members;eachh'avingan unobstructed relatively" small bore' compared to that of the tubingstring, j and a "short 'section ioftubing 'joining' t he said tubuIar me'mbers and having'ythe same bore-as 'the' tubing strin said tubular membersand tu- ""bular section being" in. axial alignment and formthen be driven into the well by allyhniform imobstructed bore from endfto eeuonai areathan that'of the tubing string and a length at least 3times its diameter pper tubularimember said tubular section ha'v- V for spotting a fiuid'rnaterial at "'ing' a eontmuous passage fonfluidiaiid' forare- V 13 silient compressible tubing plug making a sliding sealing fit with the bore of the tubing string.

4. An apparatus for spotting a fluid in a well for use on the lower end of a string of well tubing in combination with a resilient compressible tubing plug driven by a driving fluid through the bore of the tubing behind the fluid being spotted, the plug producing a pressure increase on being driven into the apparatus signalling completion of spotting and there acting as a back-pressure valve preventing the return to the tubing of the spotted fluid, comprising a tubular assembly having an upper, a middle and a lower section all connected in tandem forming a continuous passage from end to end, the upper end of the tubular assembly having means for attachment to the lower end of the string of well tubing, the crosssectional area of the bore of the said upper and. lower sections being between about 25 and 70 per cent of that of the said middle section, the cross-sectional area of the bore of the said middle section being substantially the same as that of the tubing string, said middle section having a length sufiicient to accommodate in its bore the resilient compressible plug driven thereinto through the upper section by the driving fluid, the lower end of the said upper section having a shoulder adapted to engage the upper end of the resilient plug to close the passage when urged upwardly in the said middle section.

5. An apparatus for spotting a fluid material in a well for use on the lower end of a string of tubing suspended in the well comprising an upper tubular member having a constricted axial bore therethrough, means at the upper end of said upper tubular member for attachment to the lower end of the tubing string, said upper tubular memher having an annular recess in the lower end; a coniform projection in the annular recess; a lower tubular member having an axial bore therethrough; an intermediate tubular member connecting the upper and lower tubular members said intermediate tubular member having a crosssection substantially the same as that of the string of tubing, the cross-section of the bore of said upper and lower tubular members being about 25 to per cent of that of said intermediate tubular member, whereby a resilient compressible plug making a sliding sealing fit in the bore of the string of tubing requires the application of a substantial additional driving pressure to force the plug from the tubing through the said tubular members as the fluid material is delivered to the well through the tubing string.

JAMES D. HAYNES. O'RLIN W. LYONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,057,789 Wigle Apr. 1, 1913 1,791,874 Rodgers Feb. 10, 1931 1,994,072 Hardcastle Mar. 12, 1935 2,071,389 Crowell Feb. 23, 1937 2,268,010 Baum Dec. 10, 1941 2,295,822 Armentrout Sep. 15, 1942 2,370,833 Baker Mar. 6, 1945 2,382,578 Penick Aug, 14, 1945

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