US2630179A - Method of and apparatus for cementing wells - Google Patents

Description

March 3, 1953 c. c. BROWN 2,630,179.

METHOD OF AND APPARATUS FOR CEMENTING WELLS March 3, 1953 c. c. BROWN 2,630,179

- METHOD OF AND APPARATUS FOR CEMENTING WELLS Filed June 24, 1949 4 sheets-sheet 3 uuuwilguuumm @fw A( Bg@ E723@ ATTORNFYJ March 3, 1953 c. QBROWN 2,630,179

METHOD OF ANO APPARATOS FOR OEMENTING WELLS Filed June 24, 1949 4 Sheets-Sheet 4 C/cero C. Brown J/vl/f/vO/ffI ATTOR/VfYJ Patented Mar. 3, 1953 UNITED STATES Pure-,NT

oFF!- adwarev1 METHOD oF] AND APPRATUS'FORE CEMENTING WELIas-f Cicero C'. Brown, Hoiistonguflcxi Application .Time 24, 1949, s'riarN. 10110'50' is" oiaimsa (c1.'16e-'14) This invention' relates to new and" useful'll'improvements in methods of and apparatus' for cementing wells.

As is well known, the usual cementin'g operation is carried out` by introducing the cementv slurry into the upper portion ofthe Well' p'ip'e or casing and pumping the same downwardly 'therethrough with the cement bein'g'for'ced outwardly from the pipeV or casing through a backep'ress'ure' cementing Valve' at `the lower portion ofthe'j pipe or in the case of a squeeze cementing" opera'- tion outwardly through perforations in. the pipe, or casing wall. The well is-lled with fluid or mud yand thecement slurry is introduced asl by pumping and under the pump pressure forces the fluid outwardly in advance offtlie cement. After the required amount of cement has'been introduced a motivating or driving u'idfollows said cement and is-pumped-behind the cement column` to pump said cement downwardly tothe point or. elevation off its discharge, fromthe well pipe.

In order to separate the cement column from the fluid in'advance thereof as well as from the following or'motiv-ating fluid behind said` `column to prevent contamination of the cementcolumn and to` allow consolidation,thereofit is` desirable to introduce separation plugsii'otadvance` of and behind said column. Because the Well pipe must be closed duringA the introduction ofthe cement under pressure, the' introductionof the separation plug elements has presented a problem because obviously,` the pumping. operation must be interruptedv and the system" opened' to' allow insertion of said plugs. Not only-'is the interruption of the pumping operation-undesirable but` also accurate determination of the. exact' time of insertion of the plugs" is diifcult, with the result that the plug elements may loe` erro,- neously placed with' respect to the',cernentcolinn'.`

In the copending application', Serial No. 75,451,

ledFebruary 9, 1949, an improvedmethodof' ing a' plurality of separation plugs'intoa" well pipe which method is an improvementon my copending application above' referred to.

An* important object of"y the invention;` is"` to provide an' improved." well cementing" method wherein a' plurality of"separationplugs may be' selectively introduced into aA well" pipe without halting the pumping operation or opening the system', whereby'a continuous cementing opera.- tion-maybecarried'outa Another object' is; to 'provide an improvedcontinuous" cemen'ting method" which comprises, starting thepumping'operation, inserting aseparation plug, int`o-the` Well" pipe inl advance-of the cement'` slurry; withoutinterruptingf the` pumpingpperation, continuing the pumping operation to 'pump the cement' slurry under pressure downwardly through the well,` pipe, andthen introducing a sep-aration 'plug :behind the cement: without interrupting'` said pumping, wherebyl b'oth plugs are properlyplaced" andthe cement is pumpediin'tothewell'bo're in a continuous opera,- tion. l

A further object ofthe' invention is to provide ariirnproved' apparatus" for' introducing a` plu r'alityt'ofseparation plugs ina wellpipe in. a desired` relationship with respect toa cement column'a'sfthelattefis b'eingiintroducedinto a well pipe' under pressure,` which apparatus includes means'for" supporting the plugs in` position for ini'iro'ductiori` into the well pipe, together` with manually actuated control means operable'from exteriorly of the" apparatusfor" selectively introducingl the' pliigsfnto' said'v pipe at the desired instant',v whereby' proper positioning of the plugs relative to' the' cement column may be `accomplished without" halting the pumping'operation;

Still' anotherA object is to provide anl apparatus, of the character described, wherein the plugs areinitiallyflat'c'h'ed' in position within a' chamber; which communicates with the wellppe, but which is outof" thesdirect line'of inlet lowto thei'pipe, together' with means" for utilizing the linepressure for assuringa release of theplugs andintroductionthereof into the well pipe at the predetermineddesiredftimes Pr particular' object is to provide an improved apparatus; ofthe-character described, whereina manually operablejvalvewrneansis associated with each separation plugandsaidvalve means functions to control the application of line-` pressure to'the"separation` plug whereby said line'pressure may act againstthe plug to assurelits introduction* into the wellpipef.

K A still furtlienobject is toprovide an apparatus; ofthecharacter described', wherein the valve means f associatedr'withf adjacent separationv plugs co`a`ct` with eachother"to` control thev flow from the 'inlet'l line Yto th'ewell' pipe; with such control selectively' directing the line pressure against 3 each plug as the same is to be introduced, whereby a continuous uninterrupted cementing operation may be carried out.

Other and further objects of the invention will appear from the description of the invention.

In the accompanying drawings, which form a part of the instant specification, which are to be read in conjunction therewith and wherein like reference numerals are used to indicate like parts in the various views:

Figure 1 is a schematic view of a well bore and well pipe or casing and showing an apparatus constructed in accordance with the invention mounted on the upper portion of said pipe,

Figure 2 is a similar view illustrating the lower separation plug in position within the well pipe and illustrating the cement slurry being introduced,

Figure 3 is a similar view illustrating the upper plug introduced behind the cement and showing said cement being pumped through the lower plug which has reached a position in the lower portion of the well pipe,

Figure 4 is an enlarged transverse vertical sectional view of the upper portion of an apparatus constructed in accordance with the invention, and illustrating both plugs latched in position prior to introduction into the well pipe,

. Figure 5 is a continuation of Figure 4,

Figure 6 is a horizontal cross-sectionalV view taken on the line 6--6 of Figure 4,

Figure 7 is a horizontal cross-sectional view taken on the line 'I-I of Figure 4,

Figure 8 is a horizontal cross-sectional View taken on the line 8 8 of Figure 4,

Figure 9 is a View similar to Figure 4 and illustrating the lower separation plug released from its latched position,

Figure 10 is a continuation of Figure 9, and

Figure 1l is a transverse sectional View of the upper portion of the apparatus showing the upper plug released therefrom.

In the drawings, the numeral I designates a well bore having a well pipe or casing I I extending therethrough. The well pipe is arranged to belowered within the bore I in any suitable manner and has an upwardly closing back pressure valve I2 coacting with fluid outlet openings I3 in the lower portion of the pipe. During running in or lowering of the well pipe or casing the pressure 'within the well bore exteriorly of the pipe and acting against the lower end of the valve I2 maintains the same in a position closing the openings I3 toA prevent entry of fluid into the pipe. The valve is automatically moved downwardly to uncover and open the ports I3 Whenever'the pressure within the interior of the pipe string exceeds the pressure within the well bore. As is well known, the well bore is ordinarily lled with fluid or mud and the well pipe is lowered through such huid; during the lowering operation the interior or bore of the well pipe is lled with fluid in any suitable manner whereby when =the well pipe is landed in nal position as shown in Figure 1, the casing is filled with fluid to a 'desired level. After the pipe or casing string has b-een lowered into nal position it is desirable to carry out the usual cementing operation and ordinarily cement is pumped downwardly through the pipe string and being under pressure functions to force the fluid within the pipe string outwardly through or past the valve which is opened by said pressure. The cement then flows outwardly into the well bore through the outlet portsAI3 and rises to a predetermined height around the well pipe or casing to permanently bond the lower portion of the pipe within 4the well bore.

In order to separate the cement column from the fluid which is present within the well pipe it is desirable to introduce a plug into -the pipe immediately in advance of the cement column. It is also desirable to introduce a second or iollow-up plug immediately behind the cement column since a driving fluid for maintaining the pressure on said cement column is employed for finally pumping the cement completely outwardly into the well bore. The present invention is concerned with the introduction of a plurality of cement plugs with one of the plugs being introduced in advance of the cement column and the other .being introduced immediately behind or on top of the cement column. As will hereinafter appear the plugs may be properly inserted within the well pipe or casing at the proper instant and without the necessity of halting or interrupting the pumping operation by which the cement is -b-eing introduced and without opening the well pipe or casing to atmosphere.

In carrying out the invention th-e improved apparatus A is adapted to releasably retain a pair of separation plugs B and B' and said apparatus is mounted on the upper end of the pipe string, being provided with a radial inlet conductor I4 which communicates with the interior of the apparatus and with the bore of the well pipe below the lowermost plug B. The cement may be introduced through the conductor I4 and will flow downwardly into and through the well pipe or casing. The plugs B and B' are mounted in superposed relationship within the apparatus and are normally disposed out of the line of flow from the inlet I4 to the well pipe II. When the pumping operation is started to begin the introduction of cement through the inlet I4 the lower plug B is released so that it may enter the well pipe II in advance of the cement, as illustrated in Figure 2. When sufficient cement has been introduced behind the separation plug B the second or upper plug B is released so that it may enter the pipe I I behind or on top of the cement column. The release of both plugs into the well pipe (Figure 3) in proper position with respect to the cement column is accomplished without opening the well pipe or casing to atmosphere and without interrupting the pumping operation so that the pumps may be continuously operated from the start to the finish of the cementing operation.

The lowermost or advance plug B' is adapted to permit the cement to pass therethrough, as will be explained, after said lower plug reaches its nal position within the pipe. The upper plug B travels downwardly through the well pipe behind the cement as the operation continues and said plug functions to separate said cement from the driving fluid. When the cement has been discharged through the outlets I3 in the lower portion of the well pipe or casing the uppermost plug B llnally abuts or engages the lower plug B' and said upper plug is constructed so that upward displacement or movement thereof within theA pipe is impossible. In other words, the upper plug B is provided with means actuated by an excessive pressure therebelow which will firmly lock said plug against upper displacement in the well casing. In this manner the upper plug will form a closure which will prevent the cement from being forced back upwardly through the well pipe the event that excessive. pressure might fdevelop in the well 4bore and act against the lower rend of said plug `through theoutlets 13.

The apparatus A Vis clear-ly shown in Figures 4 and 5 and includes-a cylindrical body for housing having a radial inlet opening 2.! in the 'lower portion of Aits wall and provided `with an annular valve sea-t member 22 below `said port. The seat member lis Aformed with -an .annular `valve -seat or seating surface 23 `at its Vupper portion. .A coupling collar 24 is welded or otherwise `secured within the inlet opening 2:! and is `adapted to receive the end-of the inlet ipipe or .conductor .I4 through which the `cementland `pressure iluidare introduced into the well-.pipe lll.. The lower end of the valve seat :member 2:2 iis threaded into `a mounting sleeve .25 which is vrotatably :secured toa pipe section "26 :by means vof `ball `:bearings 21. The pipe `section 26 has its lower end arranged to be coupled to the upper end of `the `pipe or casing string .i l. The retaining balls 21 `are confined 'within` annular recesses `28., formed in lan annular ring member 29 which is weldedor otherwise secured to the section 26 Aby means of threaded plugs 30 threaded into the sleeve 25. Obviously, said ball :bearings 21 rotatably couple the parts to each other. By removing the plugs 30 the balls may be .removed vto permit the `body 2!) to ibe .disconnectedfrom the pipe .section `2G. Suitable packing rings V3?! :pack off between rthe pipe section 2-6 and vthe mounting sleeve `25 as well as between the ring .member 123V and said mounting sleeve. `Sincethe .pipe vsection 26- has its lower endcoupled to the .upper end of the pipe string or casing L! the housing 20 is rotatably mounted on said pipe or `casing whereby the casing may be rotated while the housing remains stationary. l

The upper end of the housing 20-is vclosed by a hanged cap member 32 which is threadedonto said upper end and `a suitab-le packing ring 33 seals off between the cap or closure and said housing. A clevis or ring 34 is secured to the center of the cap or closure 32 whereby a cable or line may be utilized to support the housing 20 as it is connected and disconnected from the well pipe or casing I l.

As has been noted, the separationplugsB and B are adapted to be releasably mounted within the lhousing 23, and the lower plug B is associated with a tubular valve element 35 which is located in the lower portion of the housing. This valve element has an axial `bore 35a extending entirely therethrough andhas a beveled seating surface 33 on its lowervend with a similar `beveled seating surface 31 at its upper end. The external diameter of the valve sleeve 35 is less than the diameter of the bore 23a ofthe housing 2B and said sleeve is maintained in axial align- -ment within the housing by means of longitudinal ribs or keys 38 formed on its external surface (Figure 8) and coacting with longitudinal grooves or keyways 39 provided on the inner surface of the bore 23a of the housing 23. The coacting keys and keyways not only align the valve sleeve 35 axially within the housing but'also function to prevent a rotation of said sleeve with respect lto the housing as well as to guide said sleeve in its axial movement within said housing.

The valve sleeve is formed with a longitudinally extending gear` rack 4B on its external surface and said rack is adapted to be engaged by a rotatable pinion 4! which is mounted on the inner end of an operating shaft 42. The operating shaft extends outwardly through a radial opening 43 iin the `housing and is rotatably mounted lin a suitable'bearing sleeve 44. `The outer end of the rotatable shait 42 is Aprovided with a hand wheel 45 to facilitate .manual rotation of said shaft and the pinion 4! secured thereto. Normally the hand wheel `may be locked against operation by means of the locking pin 43 which extends through an opening :in the web in the `hand wheel and .which :has its inner endengaged within locking flugs 41 which extend radially from the mounting collar 43a surrounding the .opening 43. It `will .beevidentzby observing Figure v4. that when .the locking pin 3.6 is extending Athrough the hand -wheel and engaging the locking lugs a rotation of the hand wheel ris prevented, with the result that the Aoperating pinion 4! cannot be rotated. Removal of the looking pin 46 permits the hand wheel 45and shaft 42 to .be rotated, whereby the pinion 4l .rotates `and through its engagement with the gear rack 43 lon the valve sleeve 45 imparts a longitudinal or axial movement lto the valve sleeve within the vboreof the housing 20a.

The valve sleeve is normally in the position shown in 'Figure 4 `.which may be termed its upper positionand .u-ponoperation of the pinion il vmay be moved downwardly to Athe position shown in Figure '10. `In its `upper position the valvesleeve 35 has its Ilowerendclear of the inlet E! whereby the dow from the `inlet may pass directly into the 4well vpipe i! l. In its lowered positionlthe valve surface 36 at the flower end `of the valve sleeve 35 will engage the annular valve seat 23 `within the lower portion of the `housing .23 below the inlet 2i CFigure l0) and in such `position direc-t flow from the inlet 2i! tothe -well pipe is prevented. In such case the ow from the :inlet will be upwardly `around the valve sleeve 35 and into the upper end of Vsaid valve sleeve as indicated by the-arrows in Figure 9, after which `flow will `be downwardly `through the valve sleeve and into the well pipe lThe lower plug B is adapted to be normally retained within the `va-lve `sleeve 35 and `said plug `includes a tubular mandrel 48 which may be made `of any upper section .43a and a lower section 4.31) connected together rby threads. An axial bore 49 extends entirely through the man- .drel l118 and `is normally closed at its lower vend by vmeans of a frangible disc 50 which may be threaded into the lower portion of said bore. An outwardly flared elastic packing element 5! is mountedfon the lower end of the mandrel and has its 'iiared lip `portion 52 directed downwardly. A similar flared packing element 53 having its lip portion 54 directed `upwardly is mounted on the upper portion of the mandrel and when the glug IB is within the valve sleeve 35 the upper packing element 53 is below the upper end of said valve sleeve. Pressure equalizing por-ts 55 extend through the valve sleeve 35 adjacent its upper end `so that when the plug B is in position within the valve sleeve 35 pressures across the plug may be equalized.

The `plug 'B' is normally :latched within the sleeve valve 35 by means of latching dogs 56. Each dog `extends through `a radial opening 51 in the valve sleeve 35 and has its inner end normally engaged with a recess 58 formed in the exteriorsurface `of the mandrel 48. Each dog has its outer end attached `to a bowed spring member 59 and when the valve sleeve 35 is in a raisedposition as shown in Figure 4 the spring 59 is disposed opposite a projection `3!) which is secured to the wall 29a of the housing. VItwill `beapparent thatiwith each latchingdog opposite its complementary projection 60 said latching dog cannot be retracted from the recess 58 in the mandrel and thus so long as the valve sleeve 35 is in a raised position the plug B' is locked within the valve sleeve.

When the operating pinion 4| is rotated to impart a downward longitudinal movement to the valve sleeve the latching dogs 5B are moved below the projections 60 and the tension of the bowed springs 59 moves said springs to the position shown in the lower portion of Figure 9 whereby the latching dogs 56 are retracted from their respective recesses 58. This results in a release of the plug B' allowing it to fall downwardly into the well pipe ll. It will be evident that as the valve sleeve moves downwardly into engagement with the seat 23 (Figure l0) the flow of pressure fluid entering through the inlet 2l will be directed upwardly around the valve sleeve 35 and into the upper end thereof behind or on top of the plug B'. Thus the full force of the pressure iluid which at this point will be cement is directed against the plug B to assure that it will move downwardly out of the valve sleeve 35 and into the well pipe Il.

The upper plug B is normally mounted within an upper valve sleeve 5l which has an axial bore 82 extending entirely therethrough. The lower end ci the upper valve sleeve is formed with an annular seating surface 53 which is adapted to be engaged by the seating surface 31 at the upper end of the lower valve sleeve 35. Pressure equalizing openings 64 are formed in the extreme upper end of the upper valve sleeve 6I and in its upper position said upper valve sleeve may engage the under side of the cap or closure 32.

The upper valve sleeve 6l is mounted in a manner similar to the manner of mounting of the lower valversleeve being non-rotatably conned and guided in its longitudinal movement within the bore of the housing by coacting keys and keyways 38a and 39a. The upper valve sleeve has a longitudinally extending gear rack a which is in constant mesh with an operating pinion Illa. rThe operating pinion is carried by an operating shaft 42a mounted in a manner similar to the shaft 42 of the lower valve sleeve and a hand wheel 45a located exteriorly of the housing permits manual rotation of the pinion Ala. A locking pin 45a prevents accidental operation of the hand wheel.

It will be evident that the upper valve sleeve 6| may be moved longitudinally within the bore of the housing 25 by means of the pinion 4Ia and gear rack 40a. sleeve 5| is as shown in Figure l and with the lower valve sleeve 35 in its raised position has its lower end engaging the upper end of said lower sleeve. When the lower sleeve has been moved downwardly as illustrated in Figure 9 the upper valve sleeve 6I may be subsequently moved to its lower position as shown in Figure 11 and in this position the lower end of said upper sleeve again re-engages the lower valve sleeve 35. The sleeves Si and 35 are of substantially the same diameter so that when said sleeves are in engagement with each other they form a continuous conductor. Y

The upper plug B is arranged to be releasably mounted in the upper valve sleeve 6I and includes a tubular mandrel 65 which has the lower portion of its bore closed by a transverse partition or plate 65. A downwardly directed ared packing element Bl is mounted on the lower portion of the mandrel while an upwardly Adirected flared In its upper position the valve packing element 68 is mounted on the upper end of said mandrel. Intermediate its ends the mandrel is formed with a conical slip-expanding surface 69 upon which a plurality of segmental gripping slips 10 are slidably mounted. The upper ends of the slip members are attached to an annular packing sleeve 'Il which is ared in an upward direction whereby pressure from above may be sealed by said sleeve. Upward movement of the slips relative to the mandrel is limited by an external shoulder 'I2 formed on the mandrel.

The upper plug B is adapted to be latched within the upper valve sleeve 5| by a plurality of latching dogs 56a which are identical in construction to the latching dogs 56 which lock the lower plug B within the lower valve sleeve 35. Each latching dog 56a extends through a radial opening 'i3 in the wall of the valve sleeve 6l and has its inner end engaging a recess 58a in the mandrel 65. The outer end of each dog is attached to a bowed spring 59a which is disposed opposite a projection 60a on the wall of the bore of the housing when the valve sleeve 6l is in its raised position. It will be apparent that when the valve sleeve 6I is moved downwardly to locate the springs 58a of the locking dogs 55a below their respective projections 60a, said springs will function to retract the latching dogs a from their respective recesses 58a in the mandrel 65 of the plug B. When this occurs the plug B is released and may fall downwardly from the upper valve sleeve 6 I, through the lower valve sleeve 35 and into the well pipe or casing l I.

In the operation of the apparatus the parts are in the position shown in Figures 4 and 5, in which position the valve sleeves 5| and 35 are in their raised positions engaged with each other and the plugs B and B are latched in their respective sleeves. At this time any pressure entering the lower portion of the housing through the inlet 2l may pass upwardly around the sleeves 35 and 6i and may equalize around both of the plugs B and B. Pressure may enter the space between the plugs through the ports 55 in the upper end of the lower valve sleeve 35 and may enter the upper end of the upper sleeve 6l through the opening 64.

When the cementing operation is begun, the cement under pressure is pumped in through the inlet line i4'and following starting of the pumps and just before the cement begins to enter the inlet 2|, the lower valve sleeve 35 is moved downwardly by manipulating the hand wheel 45 and rotating the operating pinion fil. Through the pinion 4l a-nd gear rack 4i! the lower valve sleeve 35 is moved downwardly so that its lower end engages the valve seat 23 and this shuts oli a direct flow from the inlet 2iV to the well pipe il. The pumped cement entering the line 2l mst then flow upwardly around the lower valve sleeve 35 and may enter the upper end of said sleeve as indicated in Figure 9 because the lowering of said sleeve has separated the same from the upper sleeve. As the valve sleeve 35 was initially moved downwardly the latching dogs 55 were disengaged from the locking recesses 58 in the plugB and said plug was released from its latched yposition within the valve sleeve 35. The plug will fall downwardly by gravity into the well pipe and its release from the sleeve 35 will be positively assured because the cement under pressure is acting above said plug. The upwardly dared packing element 53 on the upper portion of the plug B will seal with the wall of the pipe Il and thus the cement under 'pres-f sure will? force the plug downwardly through the pipe. Because the plug B'v has itst bore closed byV the frangible closure or disc 5d said plug will positively separate the cement colu-mn from any iluid which may be present Within the well pipe, and it is evident that as the cement columnmoves downwardly the liuid within the pipe is forced outwardly through the outlets lf3 in the lower Iportion thereof.

Introduction ofy cement continues in this manner untilthe desired volume or quanti-ty of cemen-t has been introduced and at this point it is desirable to releasethe upper separation plug B on top of or behind the cement column. In order to accomplish release` of t'he upper plug B Without halting the pumping operation it is only necessary to rotate the operating pinion 44a through the hand wheel 45a; This moves the upper valve sleeve 6I downwardly within the housing until its lower-rl nd '63 again re-engages the upper end of the lower valve sleeve 35. This downward movement of' the upper sleeve `5I results in a release of the latching dogs 56a whereby the upper plug B is` released from the valve sleeve `[il and may fall downwardly therefrom. At the same time the downward movement of the upper sleeve` to the position shown in Figure l1' causes the pressure fluid which is utilized to drive the cement column downwardly within the well pipe to ow upwardlyr around the upper sleeve 6l to its upper end as indicated bythe flow arrows in Figure l1. Thus, this pressure :fluid is` applied against the plug B and `urges said plug and the cement column in advance thereof downwardly through the well pipe II.

After both plugsy have been introduced with the cementY column therebetween the plugs and column moves downwardly throughthe well pipe asa unit until the lower plug B' engages an annular seat or projection 'l5 within the lower por-V tion off the pipe. The continued application of driving fluid pressure then results in a fracturing or breaking of the frangible closure disc` 50 in the lower plug whereby the cement may then pass. through the lower plug. It isA noted that the provision of the frangi-b'le disc 50 permits the cement column to consolidate `before it is finally pumped out of the well pipe. Uponpassing through the lowerplug B`the cement is then discharged through the outlet ports I3 in the lower portion of the well pipe and the lupper or follower plug B follows the `cement until said plug strikes the lower plug.

It is noted that the upper or :follower plug B is provided with the segmental slips l0 which will function to prevent an upward movement of this plug with respect to the pipe. Thus, in the event that the pressure below .the cement column becomes excessive to the point ofv overcoming the pressure of the driving uid there would 'be a tendency for the cement column and upper plug to be moved upwardly within the well pipe. Anyexcessive pressure against the plug B` will act. on the lower packing element 6l and will move the mandrel E5 of `said plug upwardly with respect to the slips 10, said slips being held momentarily stationary by the frictional engagement of the packing sleeve 'II with the wall of the pipe. A relative upward move" ment o the mandrel v55 with respect to the slips Tl will result in -a coaction between the conical surface 69 of the mandrel and the slips `whereby the slips will be engaged with `the wall ofthe well pipe to prevent further upward movement.`

Thus .the upper plug is provided with the slip 10 members which will prevent reverse or upward iiow of the cement through the well pipe in case excessive pressures within the `well bore are encountered.

After the cementing operation is complete the plugs B' and B are located within the lower portion of the well bore as illustrated in Figure 3v and it is preferable that these plugs be constructed of a. material which is readily drillable, whereby both plugs. may be subsequently drilled out after the cement has properly `set and it is desired to, reopen the bore of the welll pipe.

From theA foregoing it will be seen that the apparatus` provides an accurate means for in-` troducing aplurality of separation plugs into a well pipe during the; cementing operation without` interrupting such operation and without having to open the well pipe to atmosphere. Be-V cause each of the plugs are quickly and easily released by a meremanipulation of the hand wheels, it is possible to introduce the plugs at the ,exactA desired instant and this assures proper placement of the plugs. with respect to the cement column. The provision of the valve sleeves 35 1 and 6l allows the pressure of the cement `or of the driving fluid to be utilized to assure that each: plug will be properly released and introduced into the well pipe. As explained, the arrangement of the upper andlower' valve sleevesy 35 and 6I is such that the ow of the pressure fluid is controlled to accomplish the results. Normally and before either of the plugsare introduced, both plugs and their associated parts are completely out of' the line of flow so that a direct flow from the inlet 2l` into the Well pipe I2 may occur. It is only when the pressure of the fluid entering the inlet 2| is desired for assuring release of the plugs that the valve members are actuated to shut off direct flow between the inlet 2| and the pipe I2.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious. and which are inherentto the structure.

It will be understood that certain features and subcombinations are of `utility and may be employed without reference `to other features and subcombinations. This is contemplated by and is within the scope of the claims.

Asxmanyy possible embodiments may be made of the invention without departing from the scope thereof it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described the invention, I claim:-

-1. An apparatus for inserting separation yplugs in advance of and behind cement in a well pipe, including, a well pipe 'having a single inlet in its upper portion whereby fluid may be pumped under pressure into said pipe, a chamberconnected with the upper end of the pipe above the inlet and communicating with the bore of the pipe, a pair of separation plug elements disposed within the chamber out of the direct line of flow of the fluid flowing from the inlet into the pipe, a lal'iching` means for releasably holding each of said plug` elements in said chamberV above said inlet, and means releasing `said latching means for selectively releasing said plug elements and simultaneously therewith for by-passing iiuid from the inlet upwardly into the chamber behind one or the other of said elements to introduce said plug elements into the pipe in ad 1 l` vance of and behind cement being introduced through the inlet without halting the pumping operation.

2. An apparatus for inserting separation plugs in advance of and behind cement in a well pipe, including, a well pipe having a single inlet in its upper portion whereby fluid may be pumped under pressure into said pipe, a chamber connected with the upper end of the pipe above the inlet and communicating with the bore of the pipe, a pair of separation plug elements disposed within the ,chamber out of the direct line of flow of the fluid flowing from the inlet into the pipe, a latching means for releasably holding each of said plug elements in said chamber above said inlet, means for by-passing cement upwardly around one of thel plug elements and simultaneously releasing said latching means to insert said one of the plug elements into the well pipe by means of the cement pumping operation, and means by-passing a driving uid introduced through the inlet around the second separation plug for inserting the second plug element into the pipe behind the cement and in advance of the driving pressure fluid without halting the pumping operation.

3. An apparatus as set forth in claim 1 wherein the pressure of the pumped fluid is utilized to effect introduction of the plug elements into the well pipe.

4. An apparatus for inserting a pair of separation plugs in a well pipe including, a well pipe adapted to extend into a Well bore, a tubular body having an inlet at its lower end, said body being connected to the upper portion of said pipe and having the lower portion of its bore in communication with the well pipe inlet and also in .communication with the bore of the inlet, movable valve means mounted in the body and arranged to be actuated to shut od a direct flow from the inlet to the well pipe whereby flow is from the inlet into the bore of the body and then around and through the valve means to the bore of said pipe, a separation plug releasably mounted within the valve means, means for releasing said plug and introducing it into the well pipe when the valve means is actuated to shut oi direct ow from the inlet to the pipe, means for introducing cement through the inlet and valve means into the pipe behind the separation plug, a second separation plug releasably mounted in the upper portion of the housing above the valve means, and means for inserting said second plug behind the cement column which has been previously introduced into the well pipe.

5. An apparatus as set forth in claim 4, together with means for utilizing the pressure of the pumped fluid to effect release and insertion into the pipe of both plug elements.

6. An apparatus as set forth in claim 4, together with a tubular valve element associated with the second plug element and movable into a position engaging the first valve means whereby the pumped pressure is directed against the second plug element to release said second plug. v 7. An apparatus as set forth in claim 4 wherein the movable Valve means is actuated by a manualmeans located exteriorly of the housing.

- 8. An apparatus for inserting separation plugs in a well pipe comprising a closed system and including, a well pipe having an inlet line in its upper portion whereby cement and other Iiuid may be pumped into said casing, a pair of cement plugsreleasably disposed within the system above said inlet and out of the line of ow from the nlet tothe pipa'and means for selectively releasing said plugs and for simultaneously by-passing fluid from the inlet around the plugs for introducing said plugs into the well pipe ahead of and behind the cement without interrupting the pumping operation.

9. An apparatus for inserting separation plugs in advance of and behind cement in a well pipe including, a well pipe having an inlet line in its upper portion whereby cement and other Jdui-"l may be pumped into said pipe, a pair of separation plugs normally disposed out or the direct line of ilow from the inlet to the pipe, tubular valve means surrounding'each .separation plug, and means for selectively operating the valve means associated with each plug for shutting oli' the direct flow from the inlet to the pipe and for vdirecting pressure againstY its respective Vplug in a direction to urge the plug into the pipe,

whereby said plugs are introduced into'the well pipe bymeans of said pressure.

10. An apparatus as set forth in claim 9, where-- in the operating means for the valve means is operable from the exterior ofthe well pipe.

11. The' method of kintroducing separation plugs within a well bore during a ceinenting operation, which includes mounting a closed separation plug within a chamber which communicates with the upper portion of the well pipe, releasing the plug from its mounting within the chamber, delivering cement into the upper portion of the well pipe and by-passing the plug within the chamber to direct said cement against the upper end of the plug simultaneously with said releasing of the plug, whereby the plug is intro' duced into the pipe ahead of the cement column, mounting a second separation plug in the cham-'- ber above the Aiirst plug, releasing the second plug toinsert it into the pipe immediately ,behind the cement column without interrupting the pumping operation whereby the plugs and cement confined therebetween are pumped downwardly through said pipe-opening by means of pump pressure the first named separation plug when said plug reaches a point within the lower portion of the pipe, whereby the cement may pass through said plug, and then discharging said cement from the well pipe into the well bore.

12. The method of introducing separation plugs into a well pipe within a bore hold during a cementing operation wherein the well pipe has only a single conductor inlet near its upper portion, said method including, releasably mounting a pair of separation plugs in superposed relation to the extreme upper end of said well pipe above the inlet, applying-pressure through a pumping operation to a cement slurry to direct the slurry into the upper portion of said well pipe, releasing the lower separation plug and simultaneously therewith shutting on" direct communication between the inlet and well pipe, icy-passing the cement slurry upwardly around the lowermost separation plug and directing said slurry against the plug to eiect insertion of the plug into the well pipe, continuing the introduction' of cement into the well pipe until a desired volurne has entered the pipe, then introducing a driving iiuid behind the cement through the single conductor inlet, releasing the second separation plug and simultaneously therewith bypassing the driving fluid which enters through the inlet upwardly around the second separa-l tion plug to apply said4 driving iuid to said sec" ond plug and thereby effect insertion of the second plug into the well pipe behind the cement" 13 column, the release of said plugs and the bypassing of cement and fluid past the same being carried out without halting the pumping operation.

13. The method as set forth in claim 1l, together with the additional step of opening the lower separation plug by the application of a predetermined pressure thereto after the plugs and cement are in a desired position within the well pipe.

14. An apparatus for inserting separation plugs into a well pipe, including a well pipe adapted to extend into a well bore, a chamber at the upper end of said Well pipe having an inlet therein, an upper and a lower separation plug disposed within said chamber, latching means for releasably holding said plugs in said chamber above said inlet whereby fluid may be directed from said inlet below said plugs in its flow to said well pipe, a valve sleeve surrounding each of 4said plugs and disposed within said chamber, and control means operated from the exterior of said chamber for axially moving each sleeve and its respective plug to direct the fluid from the inlet into said chamber above each 25 plug and to also release said latching means whereby the fluid may force the plugs downwardly into the well pipe.

15. The apparatus as set forth in claim 14, in-

14 cluding a valve seat in the upper portion of said well pipe which is disposed below said inlet and is spaced from the lower edge of the lower valve sleeve when said latching means is holding same, and said lower valve sleeve seating on the valve seat upon actuation by sai-d control means, whereby the fluid ow from the inlet directly to the well pipe is closed off so that the iluid flow is directed into said chamber and above the plug in the lower valve sleeve.

16. The apparatus as set forth in claim 14, `wherein the upper separation plug has a gripping means associated therewith to prevent upward displacement of said upper separation plug after it has been released from its latched position.

CICERO C. BROWN.

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

UNITED STATES PATENTS Number Name Date 1,662,311 Hamer Mar. 13, 1928 1,791,874 Rodgers Feb. 10, 1931 1,882,099 Trouth Oct. 11, 1932 2,197,396 Mairies Apr. 16, 1940 2,228,630 Kail Jan. 14, 1941

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