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Publication numberUS2615519 A
Publication typeGrant
Publication dateOct 28, 1952
Filing dateJun 30, 1947
Priority dateJun 30, 1947
Publication numberUS 2615519 A, US 2615519A, US-A-2615519, US2615519 A, US2615519A
InventorsCarr Charles J
Original AssigneeCarr Charles J
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Plug handling head for well casings
US 2615519 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Oct. 28, 1952 c CARR 2,615,519

PLUG HANDLING HEAD FOR WELL CASINGS 2 SHEETSr-SHEET 1 Filed June 30, 1947 HTTOENEY Oct. 28, 1952 J, CARR 2,615,519

PLUG HANDLING HEAD FOR WELL CASINGS Filed June 30, 1947 2 SHEETSSHEET 2 lNVENTGQ arrow/gr patented Oct. 28 1952 UNITED smrss PATENT orrics 1 Charles J. Carr, Long Beach, Calif. Application June 30, 1947, Serial No. 758,134

- 1 This invention has to do with a plug handling head applicable to a well casing and it is a general object of the invention to provide a simple, practical, improved structure of this general character. Plugs are used in connection with or incidental to cementing operations carried on in oil wells, it being common to employ two plugs one a leading plug to precede a body of cement into a well and the other a trailing plug which follows the body of cement. Devices known as cementing heads have been proposed and used to facilitate the introduction of the plugs into the well.

My present invention is primarily concerned with a head applicable to a well casing or the like for handling plugs and through which mud, cement, or other material may be pumped or circulated in the process of carrying out a cementing operation.

It is an object of my invention to provide a H and which can be quickly moved into position over 8 the, well where it occupies a minimum of space.

A general object of my present invention is to provide a cementing head which will handle a plurality of plugs and which includes means for handling the fluid introduced into the well, which head is simple, compact, and easily handled. The head construction that I have provided is in the form of a unit requiring but two connections to be made in order to apply itto, a well for operation, one the connection between the head and the well and the other between the head and a supply hose or the like delivering fluid to the head.

Another general object of the present invention is to provide a head of the general character referred to involving a fluid handling system whereby fluid can be easily, conveniently and efiectively directed to different partsof the head as the head is operated, to the end that. fluid such as mud is initially introduced under'a lower plug in the head while cement may later bev introduced into the head above the lower plug and below an upper plug located in the head, and finally mud may be introduced into the head above the upper plug.

Fig. l is a view showing the structure of the presentinvention in-operating position on the upper end of a well casing, certain parts of the construction being broken away to show in section and the structure being shown carrying two plugs and in condition ready for operation. Fig. 2 is a plan section taken as indicated byline 2-2 on Fig. 1. Fig. Sis a side elevation of parts shown in Fig.- l, certain parts being shown in section and 3 Claims. (Cl. 166-44) the control latch which normally supports it in part of the head showing a latch mechanism included in the construction. Fig. 5 isa detailed sectional view of the part shown in Fig. 4 being a view taken as indicated by lined- 5v on. Fig. 4. Fig. 6 is a transverse sectional view of the parts shown in Fig. 4 being a view taken as indicated by line 65 on Fig. 4. Fig. '7 is a side elevation of the constructionshown in Fig. 4 certain of the parts being shown in section on the line indicated as '|--l on Fig. l, and Fig. 8 is a view similar-to Fig. 5 showing the latch released and the plug previously supported by the latch in process of passing the latch.

The construction that I have provided involves,

quick handling of the head, releasable stop means I5 supported by the body [0 and controlling movement of plugs within the head, pressure equalize ing means H5 communicating with various porsubstantially the same diameter as the well cas'e ing C to which the head is to be applied, or at,

least it is of such size as to accommodate plugs operable in the casing. The body 10, as shown in the drawings, is asimple straight tubular part with its lower end open or in communication with the upper end of the casing C and with its upper' end closed by the cap [2.

The coupling means I l is a releasable coupling:

and serves to releasably connect the-lower end of the body H) to the upper end of the casing C and since my present invention is in no way concerned with the details of. such coupling or connection I. have merely indicated a conventional "coupling. of a type that is quick acting andwhich will serve to effectively and securely couple the body l0 to the casing C. i

The cap l2 serves primarily as a closure for the upper end of the body Ii] and in practice it may be secured to the body in any suitable man- In the case illustrated the cap is shown provided with a dependingflflangel8 screw threaded to the upper end of the body-I0.

The plug stop [3 that I provide is located in the upper end portion of the body i0 and serves as a positive stop to limit upward movementof'j the head. Fig. 4 is an enlarged elevation of a" the uppermost plug A in the body, the stop serving to position the plug A in the body so that there is a chamber or space X left in the body above the plug or between the plug and the cap, as clearly shown in Fig. l of the drawings. In accordance with the preferred form of my invention the stop i3 is carried by the cap [2 and when this construction is employed the stop may be in the form of a depending projection QEI'eXtending downwardly from the lower end of a shank 2| centrally threaded in the cap. A look nut 22- is shown applied to the shank to set it in the'desired position in the cap. In practice the projection 20 depends a suitable distance into the body ill from the cap and is such as to engage a suitable partof the plug. A, as for instance, the core 23 of the plug as shown in Fig. 1. It is to be observed'that'the projection 20 extends far enough down into the body I'll to-stop the plug'A so that its upper end is spacedsomewhat'below the lowermost" part of the cap, that is 'below the flange I8 of the cap.

The supporting means I' l provided-to facilitate handling of the head ispreferably a swivel connection applied to or carriedby the cap 12' and isisuclr. as to make connection with an operating linei'h; or' the like. means I4 is shown as including a yoke-shaped bracket 24 rotatably supported'on an upward extension 25' of shank 2| and carrying a horizontally disposed pivot pin' 26 which holds a rope sockettZI or the like which, in turn, receives and holds the line L. Through this construction the head? is': readily rotatable relative to the line L and. can. freely swing about the pivot pin 26, making the head easy to handle in the derrick in the. course of being applied to or removed from thecasin'g C.

The releasable" s'top means 15 includes one or more units, preferably like units, and in a typical caseiwhe're the head is to handle two plugs, an

upper plug A and a lower plug B, the structure includes two stop units. Each stop unit'is preferablyin the nature of a latch mechanism and, in accordance with the construction that I have provided each latch unit is such that it may serve either to stop downward movement of a plug, upward movement of a plug, or it may even simultaneously stop downward movement of one plug while it stops upward movement of the other plug, stopping' such plugs in spaced relation within the body.

In the particular case illustrated the head involves two stop units or two units of the means which units are alike and the uppermost of which is located toserve as a stop to prevent downward movement of the upper plug A at the same time that it prevents upper movement of the lower plug B while the lowermost unit is located to serve so ely as a stop for downward movement of the lowermost plug. In practice I may employ a plurality of units servin to stop plugs in both directions. In cases where the plugs require greater support than is afforded by one unit, for instance, when the plugs used and the head employed are of large diameter, a plurality of units l5 may "be usedat a single pointlengthwise of the head, and such units may be suitably spaced around the body H of the head.

I will describe but one of the units of means I5, for example the uppermost unit, as shown in. the drawings; it being understood that such description is applicable to both unitsor to as many units as may be included in the head.

In the case illustrated the The stop means 15 in itspreferred form in volves, primarily, a shiftable latch 30 and suitable supporting and controlling means for the latch. In the case illustrated the latch 38 is a pivoted latch, in which case it is carried on a rotatable shaft 31 and the shaft in turn is rotatably supported by a housing 32. A stop 33 on the latch positively stops the latch in full operating position where it prevents movement of a plug in either direction past it in the body In. A means preferably, a spring means, serves to normally yieldingly hold the latch in full operating position and a manually operable control means 35 controls operation of the latch, preferably through the supporting shaft 3|. In the preferred form of the invention I provide indicating means 36 whereby the operator can readily determine the position of the latch.

The latch 30 in the preferred form of. construction is in the nature of a latch plate 40 carried by the shaft 3| which is located outside of the body Ill and having aplug stopping portion normally projecting into the body l0 through a latch opening 43 provided in the side of the body. In the particular form of latch illustrated the portion which projects into the body to stop the plug or plug-s as the case may be is somewhat triangular in form and has an upper stop face 44 to be engaged by the lower end of a plug above the latch and has a lower stop face 45 to be engaged :by a plug below the latch. The top face 44 in the case illustrated is a straight or flat face shaped and proportioned to suitably engage the lower end portion of the upper plu A while the lower face 45 is a curved face concentric with the axis of shaft 3|.

The stop 33 provided on the latch 30 is in the nature of a projection on the latch plate 40 at which may be termed the inner end of stop face 65 the projection being proportioned to engage a suitable fixed part to positively limit inward swinging movement of the latch plate in the manner indicated in Fig. 5 of the drawings.

The housing 32 may be a cup-shaped structure applied to the exterior of the body In at the opening 43 to provide a latch chamber 46 which is closed except for access to the interior of the body I0 through the opening 43. In the case illustrated a suitable mounting pad 50 is provided on the exterior of the body It) surrounding the opening 43 to carry the housing 32. The housing 32 is shown as including spaced vertical sides 5| and 52, an outer end 53 extending between the sides, a top 54 and a bottom 55, these various parts of the housing being preferably integrally joined, in which case the housing may bea. simple cast unit.

The shaft 3! carrying the latch plate extends through the latch chamber 46 between the sides 5! and 52 of the housing and it is rotatably supported in suitable bearing openings 56 in the sides of the housing;

The means 34 provided to normally yieldingly urge the latch to normal position may include asimple' compression spring 68 located in thelatch chamber 46 between the top 54 of the housinganda shoulder 69 on the latch plate, these parts being located and related so that the spring operates between an extended or fully operating position,. as shown in Fig. 5 and a compressed position as shown in Fig. 8.-

The control means 35 for the latch 30 preferably controls the latch through the shaft 3| and in the particularv form illustratedv in the drawings the means 35involves a latch pin that is manually operable and which is carried by the housing to cooperate with the shaft 3!. The shaft-3| is provided at one end with an enlargement or head which operates in a chamber ll provided in the wall 52 of the housing, the outer endof the chamber being closed by a removable plug12. The headflq has a flattened side 13 normally engaged by the pin. I

The latchpin is shown carried by a boss 15 on the housing and in the form illustrated it includes an inner control end portion 16 which engagesand cooperates with the fiat side 13 of head 10, and it includes a shank ll located within the boss and carrying a stem 18 which-projects at the exterior of the boss. The pin just described is slidably carried in a bore 19 provided in the boss 75 and a suitable handle orhead 80 is provided on the outer end of the portion 18 to facilitate convenient manual operation of the stem.

"When the latch pin is down or in operating position, as shown in Fig. 7,. the control end 76 is 'inengagement with the flat side 13 of the head 10 on shaft 31, thus positively preventing rotation of the shaft from a position where the latch'plateflfl is in plug stopping position as shownin Fig. 5. When the pin is operated, that is, 'when it is moved upwardly from the position just described, the control end 16 ofthe pin is ward press reon'the plug engaging the .stop face.

44 of the'latch plate will cause the latch plate to bejdepressed or released to the position shown in "Fig. 8, whereupon the plug is free to slide past thelatch in orderto enter the well casing to which the head' is connected. i

Inthe preferred form of my invention I provide detent means for releasably holding the latch pineither in the operating or down position, or in the released position. In the case illustrated a spring presseddetent 81 is carried bythe'boss T5 and cooperates with reduced-parts or recesses 82 in the shank of the latch pin. The recesses'82 are spaced so that .when the detentis engaged in. one recess the pin is down as shown in Fig. '7, whereas when it is engaged in the other recess the pin is up'and the latch free to release the plug;

In practice I preferably provide against leakage around the shaft 3]. For instance, I may provide packing 83 around the shaft or in engagement with the head H! of the shaft, as shown in Fig. 6, and I may provide suitable packing 84 around the other or projecting end of the shaft.

The indicating means 36 preferably provided in the construction may include a simpleindicater- 85 fixed on the projecting end of the shaft which indicator may be in the form of a pointer asshown in=the drawings indicating therotative position of the shaft so that the operator can readily. determine whether the latch plate on the shaft isup'as shown in Fig. 5 or down as shown in;- Fig.-8. -'-In the preferred construction aguard flange 86' is provided on the housing to surround or protect the indicator 85, preventing accidental injury thereof.

The pressure equalizing means l6 that I have provided may be any suitable form of fluid piping a T' fitting: I 9 i communicating with Jthe cham-* ber Y, and suitable pipe connections "Hi2 be-} tween and joining the fittings- The fiuidsupply means 1 1 that-I have provided 1 preferably includes a vertically disposed stand pipe spaced to the one side of the body 10, a releasable coupling 9| -on theilower end of the stand pipe for coupling it to a'supply line such as a hose. H, I or thelike, and a, plurality of lat eral branches 92, 93 and 94-couplingthe stand' pipe to the body- In at different points vertically prefer-' ofthe'body, each of which branches ably undercontrol of a valve'or'th'e like; f

.The coupling 9 I like the coupling 1 I "provided on the body l0 may be any suitable quicklyoper able coupling .and'is provided primarily to serve as a means for making connections with a suitable supply'line such as a pipe orhose; In' the particu I lar case illustrated the stand pipe is an assembly ofparts orfitting selected to best-suit the-par ticula'r design illustrated. --The number of lateral branches provided in the means l'l may'varywith the number o f'plugsto be handled by 'the'g'. head. and in a case-where tw plug areto be handled, as shown in the drawings itis desirable" to provide three'such branches. I have shown a branch 92' between pipe andthe chamber X provided'between the upper end of plug A and the cap 12. "I haveshown a branch 93 between the stand pipe and" the body ID at a point'to enterthe-bOdy be tween-the lower end'of the upper plug Aand'theupper end of the lower plug B, it being important to observe that the latch engagedby both plugs serves to hold the'plu-gs s'eparated'so that there" is a space Y 'between'them, with which the The third branch 94" branch 93' communicates. I extends between the standpipe and the body I 0 ata point below the lower end-of the lower;

plug B;

Thestand pipe, like the several branches, "is preferably a simple fluid conduit and these ele ments may be made up of suitable pipe fitting'sor connections. Inthe preferred form of the invention I provide a controlvalve for each branch of the means I! and in the drawings I have shown a control valve 95. for the branch 92, a control valve 96 for'the branch 93 and a control valve 9'! for the branch 94. The valves 96 and 91 are directly connected in the branches 93 and 94'r'espectively, whereas inthe preferred arrangementthe valve controlling' branch 92 is located'in the upper portion of the stand pipe above" the branch 93, in which caseasuitable connection-j orunion 98 may be provided in the branch 92 as To facilitateshown in Fig. 1 of thedrawings. assembly I provide a union 99 in the stand pipe between the branches 93 and 94; In practice the the stand tozestablishsthechamber; Y, this unitfof means l serving.- to: positively prevent downward move-- ment of pluggA and upward movement-of-plug B. The stop l3 positively j-prevents; upwardmoveement :of-J-plugsAa andjth'e zlower: unit of means l 5 positively preventsidownward movement-s of: 1 L

lowenplugtBn .v

As the head- .is {putt into ,operatiomfluidcsuchz; asZ-mudris circulated to: the; stand piper-8B from theisupply lineland; the :valvei- 9'! 1 is 'openedtas:

indicated in' Fig; 1 admitting such mud-into the;

body; ID-qben'eath thewlowerf: plugwB so, that the; mudiis circulatedg-from s the head; down into the casing. The pressure; equa-lizingsmeans that I: have provided equalizes the-pressurebetw een the several chambers:- When -.it is desired tofintroducesothjer fluid such as-cement into :the-rwell the: valve 91 isq closed; thevalve -96=:- is opened eand" the control zpin oiath'ejmeansq I51 supportingithe lower; plugg-B is relea'sed as qindicated in Fig: 3.-

The, desired: :fiuid; say: for: instance-cement; iis-in= troduced through the supply-line H and :the 'DIGSx-J surge thereof on the top: of plug Briorces the latch plate of the -means ii 5-:supporting-the"loweriplu to the position shown ill-Fig. 8-, so :that the plug? passes =out of;;the head randilinto *the'lcasi-ngi When the desired amountmf'cement' has-:been introduced the valveSli-iswlosed vand the: valve 95 =is opened and-the control" t'pin' ofthe -upper-T mostunit of meanstli is;-released;- Mud on othersuitable: fluid introduced through the -line 40 1 then conducted: up through the: stand pipe: throughthe branch -92 and into =the chamber-X aboveatheuppermostplug{Asethis plug is-forced down through-the bodyv l O-pa st both of theaunits of;=-' the means l 5- to enter the-:casing- C 1 and: 1501- low-:- the-body :of Y cement "down in the wel-Lasep rating the cement: and the mudintroducedthrough. the rbranch-s 93 Byproviding: equalizing means Il-p event damaging 0f :the: plugs: while: in the head due to differentials in pressure above-"- and below: the plugsmhich pressure might otherwiseoccun;

- It will be apparen-tfrom ithe gforegoingydescriptioxrthat with mymonstruction the-"plugs;are reffectively; and -dependablyy supported in :the: head a 5 5 ready; Flor; operatiomwheneverfi the-1 control" pins-- are rreleasedfiandit willjbe noted that the-i-indicators of the meansgw l 5- are such rthatjthe operator canreadilvdetermine when the latchrzplates,:are5v movedgjto lathe; releasedsppsitionibvs thezsplugsu '60 ordento-make certain-thatthe plugszhavetpassed out ofnthehead and';intozthecflslngry' Haitinggtdescribedronly a typic al-r piieferredrform andiapplicationrof myiiinventiom I :do not wish to be elimitedwon restricted-toxthe specific ,de'tailszherein set forth; butnw-ish to reserveitor myselfany wa-ria-tions -or-.-modifications-thatmay1appear tootlioseaskilledin: :theart andofall: within the: scope of the iollowingclaims.

Halvinggdescrib'ed myvinvention lolaim: s 1.", head offll'the character described including,

a1. vertically disposed tubular body' adapted to' carry a plug andi having. a; side: opening; and latch-means carried by -the' body'for" preventing movement- 0f the plug' tl-iere in includin'g; 'a hous in'g se'curedto-the exterior of the body and form int'erior df-the body through said opening, ashaffl rotatably supported by the housing, azla't'ch' plate in the housin'g and-fixed on the shaft to =l5ep'rojectable into the body; a spring normallyyield ing-lyf holding-the latch plate "positiomproject ring into the body and beneath the -plug w sup port it in the body, anda =relea'sable member car ried'- by the' housing engaging the shaft to positiv'elv holdit against 'rotation withth'e latch' plate-i in said po'sition.

2. A liead of-the'cha'racter described including;

a vertically disposed tubular body adaptedfto carry a plug and having" a side'opening; and

latch means carried by the body for preventing movement of the plug therein including; a" h"ousing secured to the body' at n the exterior thereof andiforminga latch" chamber incommun'ication with the interior of the body through said opening; ashaft rotatably supported" by theh0usln'g;.

a latch plate fixedon" the'shaft withinth'e: hous ingTto be --pr0j ectableinto' the body, a sprin'gnor mally *yieldinglyholding the latch plate in" pro'-."

jecting position" where it extends" intothe'" body? to'engage beneath an'd stop the plug; indicating;

means on "the shaft" at the exterior of the "housing revealingthe positional. the latch plate; a'n'di areleasable member. carried byr'the housing nor mally" engaging the shaft" to positively hold" it"; against rotation with the latch plate in saidlpo sition; v

3. Ahead of the character described inciuding; a vertically disposedtubular body adaptedtoi. carry "a--plug"and having a side openingyand latch means carried by. the body for preventing.

movement of the 'plug therein including, a; hous ing secured to the body" at the" exterior thereof and forming a latch chamber in communication" with theinterior of the body through said open ing; a shaft rotatably supported by thehousin'g;v

a latch-plate fixed-on the shaft in the housing; a".

spring normallyyieldinglyholding the latch'platet in projecting position where it extends'into' body;--Whe reit engages? beneath and. stops the' -plug and a pinslidablycar'riedby theh'ouslnglt and manually shiftable intoand out ofiposltion where it engages a flat side ontheshaftto posi-.

tiv'ely prevent rotationof theshaft from the-p0 Y sition= where the latch plate stops"the' plug;

CHARLES J.

REFERENCES CITED- The following: referencesare of ree'ordi-in the STATES" PATENTSK

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US54867 *May 22, 1866 Improvement in sand-pumps
US1662311 *Apr 4, 1923Mar 13, 1928Leland S HamerWell-capping device
US1735330 *Jun 18, 1924Nov 12, 1929Mabel McmahanOil-well-sealing device
US1743626 *Jul 11, 1925Jan 14, 1930Dyer Zeb ACementing head
US1750143 *Sep 18, 1928Mar 11, 1930Perkins Cementing IncCementing head
US1791874 *Feb 21, 1927Feb 10, 1931J W TannerSpecial fitting and plug magazine for cementing oil and gas wells
US2196652 *Oct 10, 1936Apr 9, 1940Baker Oil Tools IncApparatus for cementing well bores
US2246802 *May 22, 1939Jun 24, 1941KehmHeating system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2768695 *Apr 27, 1953Oct 30, 1956Baker Oil Tools IncApparatus for controllably filling well casing
US2854079 *Jul 27, 1953Sep 30, 1958L L RectorWell cementing apparatus
US2984301 *Apr 11, 1957May 16, 1961Bj Service IncHydraulic releasable latch pin
US3076509 *May 26, 1958Feb 5, 1963Erwin BurnsCementing head
US3216500 *Sep 18, 1962Nov 9, 1965Dow Chemical CoPlug injector apparatus
US3507325 *Apr 16, 1968Apr 21, 1970Byron Jackson IncWell cementing apparatus
US4047566 *Feb 27, 1976Sep 13, 1977Duke John AWell cementing method and apparatus
US4290482 *Apr 29, 1980Sep 22, 1981Halliburton CompanyPlug container
US4782894 *Jan 12, 1987Nov 8, 1988Lafleur K KCementing plug container with remote control system
US4917184 *Feb 14, 1989Apr 17, 1990Halliburton CompanyCement head and plug
US5040603 *Apr 30, 1990Aug 20, 1991Halliburton CompanySequential remote control plug release system
US5050673 *May 15, 1990Sep 24, 1991Halliburton CompanyLift through plug container for slant rig
US5095808 *Apr 1, 1991Mar 17, 1992Halliburton CompanySequential remote control plug release system
US5203408 *Dec 2, 1991Apr 20, 1993Frontier Oilfield Sales Ltd.Tool saver
US6360769 *Aug 14, 2001Mar 26, 2002Halliburton Energy Services, Inc.Multiple plug container
US7669663 *Apr 16, 2009Mar 2, 2010Hall David RResettable actuator for downhole tool
US8267196May 28, 2009Sep 18, 2012Schlumberger Technology CorporationFlow guide actuation
US8281882May 29, 2009Oct 9, 2012Schlumberger Technology CorporationJack element for a drill bit
US8297375Oct 31, 2008Oct 30, 2012Schlumberger Technology CorporationDownhole turbine
US8360174Jan 30, 2009Jan 29, 2013Schlumberger Technology CorporationLead the bit rotary steerable tool
US8365842Oct 29, 2009Feb 5, 2013Schlumberger Technology CorporationRatchet mechanism in a fluid actuated device
US8365843Feb 24, 2009Feb 5, 2013Schlumberger Technology CorporationDownhole tool actuation
US8371400Feb 24, 2009Feb 12, 2013Schlumberger Technology CorporationDownhole tool actuation
US8408336May 28, 2009Apr 2, 2013Schlumberger Technology CorporationFlow guide actuation
US8522897Sep 11, 2009Sep 3, 2013Schlumberger Technology CorporationLead the bit rotary steerable tool
US20130161005 *Dec 27, 2011Jun 27, 2013Vetco Gray Inc.Modular dart launcher with status indicator
EP0023383A1 *May 20, 1980Feb 4, 1981The Dow Chemical CompanyCementing head apparatus and method of injecting a cementing plug into a well casing
EP0274162A2 *Dec 28, 1987Jul 13, 1988Pumptech N.V.Adjustable cement head manifold
EP0377255A1 *Dec 22, 1989Jul 11, 1990Sofitech N.V.Cementing head for oil wells
Classifications
U.S. Classification166/70
International ClassificationE21B33/05, E21B33/03
Cooperative ClassificationE21B33/05
European ClassificationE21B33/05