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Publication numberUS2913054 A
Publication typeGrant
Publication dateNov 17, 1959
Filing dateFeb 24, 1958
Priority dateFeb 24, 1958
Publication numberUS 2913054 A, US 2913054A, US-A-2913054, US2913054 A, US2913054A
InventorsDean Falk Chester
Original AssigneeDean Falk Chester
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Tubing closing tools
US 2913054 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Nov. 17, 1959 c. D. FALK 2,913,054

TUBzNG CLOSING TOOLS Filed Feb. 24, 1958 2 sheets-sheet. 1

m: E m f INVENTOR CHESTER DEAN 'FALK BY; Z Z Z ATTORNEY Fig. Ib

Nov. 17, 1959 c. D. FALK 2,913,954

TUBING CLOSING TOOLS Filed Feb. 24, 1958 2 Sheets-Sheet 2 INVENTOR QHESTER DEAN FALK WMM ATTORNEY 2,913,054 i l TUBING CLOSING TOOLS v Chester Dean Falk, Odessa, Tex.

Application February 24, 1958, Serial No. 717,156

` 18 Claims. (Cl. 166-224) My invention relates" to a tool for use in series with the tubing of a well for the purpose of selectively closing the bore of the tubing to. prevent passage of well fluids therethrough in the upward vand/or downward directions. well tubing in the vicinity of a packer serving to pack ott zones of dilerent pressures or fluids in the well, the

More specifically, the tool is intended for use in 2,913,054 Patented Nov.l 17, 195?l of the packer withoutl undue deterioration of the valve means, thereby avoiding the` necessity of removing the Y assembly from the well for'repair vor replacement each time it becomes desirableto reclose the bore. Still another object of 'the invention is to provide a Y tool all the parts of which can be ruggedly.` constructed A 2come apparent during the employing a simple design so as to avoid the use of slips, dogs, keys or other similar movingparts'that may jam or otherwise become damaged and thus prevent closing or openingl of the bore'.

Other objects andk advantages of my invention will be- Vfollowing discussion of the drawings wherein: t y

Figures la, lb and 1c illustrate, in three related portions, the respective upper, central, and lower portions of an assembly wherein the present tool isemployed to close the bore of the tubing string below'the packer,-

tool serving particularly well in preventing. the ilow of applications, and include well workovers and equipment repairs. Ifthe well is'a dual-completion, it is often desirable to prevent migration of lluids from one zone of production to the other.

this assemblyv beingY shown within the casingY of a well, and portions of these figuresV being shown in cross 'section'.f Fig. 2 is 'an enlarged exploded view, partly in section, ofthe lower valve plug-comprising one part ofthe present tool. A Y

Fig. 3 is an enlarged exploded View, partly in section, of the upper valve'plug comprising another part of thev present tool.

Referring now to the drawings, Figs. la, 1b and. 1c

show vawell having' a casing C, and further showing the.Y

lower end of a tubing stringi T extending :downwardly into the well casing and connecting' at its lower. end't'o a tool joint,2a located at theupper end of a tubingl seal mandrel Ziwhich is apart ofa releasablel joint Y'in's'erie's j Y with the tubing. This rele'asable joint includes a tubing Similarly, in many wells of the single-completion type, a `packer is employed above the producing zone. In this case, it is important to prevent the uid in the well annulus above the packer from entering the production zone especially Where the uid above the packer comprises Weighted mud or salt water which might damage the production formation if allowed to enter it.

It is another object of the invention to provide a bore closing tool which may be manipulated from the ground surface when it is desired to shut oli, o'r reopen, the bore of the tubing, but which tool presents little or no resistance to the flow of iluids through the bore when not actually closing the latter.

Another object of the invention is to provide a boreclosing tool capable of positively segregating two zones on opposite sides of a packer regardless of the direction of the greater differential pressure, vor changes in that direction.

Still another object of the invention is provide a structure employing two oppositely acting plug valves which are so arranged that when both are in use, they touch each other but can not both be seated at the same time. By this novel structure one valve means may be used to dislodge and unseat the other valve means, however, Without pushing it so far that it becomes disengaged from the common valve seat tube in which both are inserted. By this structure, changes in thedilerential pressure existing on opposite sides of the valve seattubeare employed to cycle the valve plugs back and forth in the tube so that only one of them can bein seated kposition at a time.vv Thus sticking is prevented so that easy removal ofthe Avalve plugs is assured.

It is a still further object of my invention to provide a bore closing tool the parts of which can be Vused over and over again to close and-reopen the bore in the vicinity seal receptacle 1 lwhich is threadedv atits lofwer end 1c and which has a sealinglbore 1d within the barrel-.1b located between the threadedendy 1c and an enlarged; upperend 1e, the upper end 1e having a bayonet-type jointY 1f for the purpose hereinafter described. The o'ther'portion of the tubingseal Aassembly `comprises thersealmandrel 2 and the internally threaded jointfZa at'its upper end into which the lower end of the tubing string T is secured in a Well-known manner. The mandrel 2 'includes' an t upper portion 2b through which ay pin 2c is passed, which pin protrudes beyond the outer periphery of the upper portion 2b on both sides thereof, thereby providing pins for engaging therbayonet joint 1f within theiupperportion 1e of the tubing seal receptacle.k A -frangible securing means comprises a screw 1a which is threaded through the side Vof the upper portion 1e of the tubing seal receptacle and the inner end of the screw 1a ordinarily underlies a shoulder 2d on the upper portion of the mandrel 2 for the purpose of holding the pin 2c in the bayonet joint 1f. ,The lower por-tion of the mandrel 2 includes a plurality of resilient seals 2e which engage the bore 1d Within the tubing seal receptacle and form therewith a fluid-,tight joint between the mandrel 2 and the receptacle l. .This releasabletubing joint 1-5-2 is commercially available and the details thereof form no part of the present invention.

Below the releasable tubing Vjoint: is located a packer, the whole packer assembly being designated by the reference character 3, and which packer includes an inner cylindrical member 3a and an outer cylindrical member 3b which are in mutually telescoping engagement. The irlner cylindrical member 3a has an annular shoulder 3C just above its lower end and has, in addition, a conical valve seatd at its lower end. Above the shoulder 3c is a lower set of slips 4 and a slip-expanding cone j5. The upper end of the cone 5 is secured to the lower end of an vannular packing rubber 6, and the upper endv o f the packing rubber 6 Ais connected with another expanding cone 7' which, in turn, engages an annular series of slips 8. The upper ends ofthe slips 8 rest upon the lower endv of the outer cylindrical member 3b. At the lower end of Ithe inner cylindrical member 3a adjacent the valve seat 3d is a valve 9 which is hinged by a pin 9a to the lower end of the cylindrical portion 3a and is biased by a spring-9b which urges the valve to close into the valve seatd. Also, adjacent the lower end of the inner cylindrcal portion 3a,r and attached thereto, as by screws 10a, is an annular skirt which supports friction drag lingers 11 which contact the casing C in order to prevent rotation of the inner cylindrical member 3a, for the purpose hereinafter stated.

The inner cylindrical member 3a has a bore 3x therethrough, and the bore 3x includes an internally threaded portion 3y'at its upper encl.A Asealing mandrel 12 is passed through the bore 3x within. the packer 3, and the sealing mandrel 12 has near its upper end a set of threads 12y which engage the threads 3y of theinner cylindrical member 3a. Thesealing mandrel 12 also includes a plurality of resilient sealingrings 12a which are compressed against the'inner surface of the bore 3x and form therewith a huid-tight joint. The mandrel 12 also has a lower portion 12b which extends through the skirt at the lower end of the packer and below the drag fingers 11, the lower portion 12b of the mandrel being externally threaded as at 12e. At the upper end of the mandrel 12 is a collar 12d which is internally. threaded and secured on to the threads at the lower end 1c of the tubing seal receptacle 1. The lower end of the collar 12d has abeveled portion '12e which is complementary in shape with an internal bevel 31 at the upper end of the outer cylindrical member 3b.

A When the mandrel 12 is passed through the bore 3x of the packer and the threads 12y are screwed into the threads 3y in the kinner cylindrical member 3ft, -thebeveled surface 12e engages the beveled surface 3z, as best seen at the top of Fig. lb, and as the threads 12y` are further screwed into the threads 3y, the outer cylindrical member 3d -is drivendownwardly along the outer surface of the inner cylindrical member 3a for the purpose of moving the packer from an unset position (not shown) to the set position shown in Fig. lb. The downward motion of the outer cylindrical member 3b causes the frangible shear pins which hold the packer in unset position to be broken oit', and causes outward motion of the slips 4 and 8 with respect to the cones 7 and 5. The packing rubber 6 is squeezed outwardly to engage the inner periphery of the Well casing C and the packer is thus fully set.

f The particular packer and mandrel shown in Fig. lb are conventional types, commercially available, and the details thereof form no part of the present invention.

g By reference to Fig. 1c, it will be seen that the lower end 12b of the mandrel is connected by an internally threaded collar 13 to the upper end of a valve tube 14 which comprises a principal element of the present borecloslng tool. The valve tube 14 is threaded a-t both ends, and the lower end thereof is connected by a collar 15 with a sub 16. The valve tube 14 has an internal bore 14x which is smaller in diameter than the bore 12x of the mandrel 12 or bore 16x of the sub 16. At the upper end and at the lower end of rthe valve tube 14 are located respectively conical valve seats 14a and 14b.

The bore-closing tool further includes an-upper valve plug 17 and a lower valve plug 18 which may be seen in greater detail in Figs. 3 and 2, respectively. The upper valve plug 17 has a conical valve portion 17a at the lower end of an enlargement 17b. The conical valve portion 17a seats on the upper conical valve seat 14a when the upper plug 17 is fully seated in and against the valve tube 14. Above the enlarged portion 17b is located a fishing head 17C and below the enlarged portion 171; is located the main valve stem 17d. Below the valve stem 17d is located sealing means including a resilient packing ring 17e which, as can best be seen in Fig. 3, is confined between a ring guide 17f and a packing ring follovwl.'` 17g held in place by nut 17h and by a lower terminal portion 17m adapted to engage the-threads 17p. v

The lower valve plug 18 is of similar design and includes a conical valve surface 18a adapted to engage the conical seat 14h at the lower end of the valve tube 14. The lower valve plug includes a stem portion 18d, and a l'shing head 18C. As can best ybe seen in Fig. 2, sealing means is provided near the upper end of the valve plug 18 and includes a resilient sealing ring 18e, a'ring guide 18j, a ring follower 18g, a nu-t 18h and an upper terminal portion 18m. `The nut 18h and the upper terminal portion 18m are internally threaded and are screwed down upon the threads 18p for holding the sealing means tightly on the valve plug 18. In order to lighten the weight of the lower valve plug and reduce its inertia, a bore 18x is drilled upwardly into the lower end of the valve plug 18.

The sub 16 is threaded at both .ends and can, if desired, be counectedat its lower end to additional tubing (not shown). The sub 16 is provided with a pin 19 which is pressed into holes in the walls of the sub 16 for thel purpose of forming an obstruction in the bore thereof. The pin 19 stops downward motion ofthe valve plug 18 when the latter is moved out of the bore 18x into the bore 16x of the sub. Perforations 16a are provided through the wall of the sub 16 to increase the ow oi well `lluids thereinto in order to bypass the enlarged por tion 18b at the lower end of the lower valve plug 18 when the plug is resting on the pin 19. In the event'the production zone is adjacent the sub 16, the casing C will be provided with perforations P.

Operation i As stated above,` one of the principal uses for the bore-closing tool, according the the presentinvention, is in combination with a packer and, in addition, in combination with a releasable joint permitting the tubing string vlabove the packer tobe withdrawn and leave the packer and the bore-closing tool in place within the well. The illustration shown in Figs. la, lb and lc is that of a conventional packer and a conventional releasabie tubing joint in combinationwith a bore-closing tool according to the present invention. `The details per se of the packer and the releasable tubing joint are of no signicance in the combination of the present invention.

The tubing Tis attached to the releasable tubing joint comprising the mandrel 2 and the receptacle 1 which telescope together in the manner shown" in Fig. la.v The frangible retaining screw 1a supported in the receptacle wall in the vicinity of the upper enlargement 1e underlies the shoulder 2d of the sealing mandrel 2. The pin 2c is located within the slot of the bayonet joint 1f' and the frangible screw 1a retains'the mandrel 2 and the receptacle 1 in the aforementioned relative positions wherein the sealing rings provide a fluid-tight joint. The lower end of the receptacle 1 isi screwed at 1c into the upper end 12d of the packer mandrel 12 and the packer mandrel 12 passes through the packer which, as shown in Fig. 1b is in set position.

The presence of the lower portion of the mandrel 12b holds the valve 9 in open position, the'valve 9 playing no part in the functioning of the assembly according to the present invention and being shown merely for the sake of illustrating a conventional production packer. As explained above, the packer is shown in the set position in Fig. lb, the packer being set by screwing the threaded portion 12y downwardly in the threads 3y of the inner cylindrical member 3a and thereby forcing the outer cylindrical member 3b downwardly to drive the slips and packing rubber into the set position, the friction drag lingers 11 preventing rotation of the inner cylindrical member 3a during rotation of the mandrel 12 to set the packer.

vThe valve tube 14 is assembled in the pipe string below the releasable tubing joint comprising the receptacle and sealing mandrel 2. In the present illustration, Fig. lc, the valve tube 14 is attached to the lower end of the mandrel 12 at the threaded portion 12e, and presents an upwardly facing valve seat 14a. The lower end of the valve tube 14 is connected to the sub 16 by the collar 15 land presents a downwardly facing valve seat 14b. At some point below the valve tube` 14, and in particular at a distance below the valve seat 14h which distance is greater than the overall length of the lower valveplug 18, the pin 19 in the sub 16 forms an obstruction in its bore which will prevent the valve plug 1S from dropping out of the bottom of the tubing string when it is displaced from the bore 14x of the valve tube 14 as hereinafter described. When the entire assembly, as shown in Figs. la, lb and lc, has been located in the bore and the packer 3 has been set, the valve plug 17 would probably not yet be in the position shown in Fig. lc, but would be in the possession of the operator at the top of the well. In addition, the lowervalve plug 18 would not be in the bore 14x, as illustrated, but would be in the bore 16,1: of the sub 16, the bottom of the valve plug 18 resting upon the pin 19. With the valve plug 17 entirely out of the well and the valve plug 1.8 located within the bore 16x and resting on the pin 19, it should be apparent that fluid may flow freely into the tubing string from the perforations 16a in sub 16 and upwardly through the bores 14x in the valve tube 14, 12x of the lower portion 12b of the hollow mandrel 12, and upwardly through the hollow ymandrel 2 and thence to the surface through the tubing string T.

If it then becomes desirable to stop the flow of iluid upwardly through this assembly, and assuming that the pressure in the Well below the packer is greater than that in the well above the packer, it is then only necessary to lower a fishing tool (not shown) through the tubing string, through the hollow mandrels, and through the valve tube 14 and grab the fishing head 18el of the lower valve plug 18, and raise the valve plug upwardly into the bore 14x into substantially the position shown in Fig. lc. Once the valve 18 has been raised far enough into the bore 14x that the sealing ring 18e is in contact with the walls of the bore 14x, the fluid pressure from below will drive the valve 18 upwardly into full seated position wherein the valve surface 18a will tightly engage the conical valve seat 14b. However, it frequently happens that the differential in pressure reverses, and in this case it becomes desirable to prevent the temporary reversal in pressure from driving the valve plug 18 out of vthe bore 14x, in which case it would fall back down on to the pin 19 thus opening the bore to undersired passage of well fluids. To guard against this occurrence, the upper valve plug 17 is dropped downwardly from a position on the ground surface, through the tubing string T, through the -hollow mandrel 2, through the hollow mandrel 12 and into the position substantially as shown in Fig. lc. It is to be noted that the sealing member 17e passes into the bore 14x of the valve tube 14 before the valve surface 17a comes into contact with the upwardly facing valve seat 14a.

In addition, it is very important to note that the lower member 17m of the upper valve plug 17 and the uppermost member 18e` of the valve plug 18 will be in mutual contact within the valve tube bore 14x. It is, in addition, very important to note that when these members are in mutual contact, the distance between the valve surfaces 17a and 18a is greater than the distance between the valve seats 14a and 14h. Thus, if the differential pressure across opposite ends of the valve tube 14 is reversed for any reason, one of the valve plugs will force the other one into a different position. That is to say, if the valve plugs 17 and 18 while in mutual contact were both in a lower position with the upper plug fully seated so that the valve surface 17a is engaged with the valve seat 14a, and if the pressure on the lower side of the valve tube 14 were to reverse so as to become greater.

fof

Vbelow than above, the valve plug 18-would be forced upwardly until its valve surface 18a tightly engaged the valve seat 14b. In-moving upwardly in this manner, the lower plug 18 would drive the upper valve plug 17 upwardly in the bore 14x. By this means, therefore, it becomes possible to deliberately reverse the pressure differential and break loose the valve plugs Aandcause them to cycle up and down in'order to free them for subsequent removal from the bore 14x.

Note that the sealing ring 18e is far enough above the valve portion 18a that, when the upper Valve plug 17 drives the valve plugs downwardly while seating itself, the sealing means 18e will frictionally retain the lower valve plug within the bore 14x, thereby preventing the valve plug 18 from falling downwardly to the pin 19. In order to reduce the weight and inertia of the lower plug valve as much as possible, and thereby assist the sealing ring 18e to frictionally` retain the valve plug 18 within the bore 14x, the stem of the valve plug 18 has been drilled upwardly to provide a bore 18x and therei by remove such a quantity of metal as will materially reduce the weight ofthe valve plug 18.

When it becomes desirableto reopen the bore of the tubing string to the passage of fluids therethrough, it is only necessary to swab the tubing string down to such level as will insure that the fluid pressure below the valve tube 14 will be considerably greater than that above. When this occurs, the valve plug 18 will be driven upwardly to thereby dislodge the upper valve plug 17 in order to prevent sticking of the latter in the bore 14x. By this means, removal of the upper valve plug 17 by means of a shingtool will be greatly facilitated. Once the upper valve plug 17 has been removed from the tubing string, the creation of a downward pressure within the tubing string will drive the valve 18 entirely out of the bore 14x, and permit it to resume its position of rest on the pin 19 within the sub 16. At that time the bore of the tubing string will have been reopened to llow of fluid therethrough. y l

In the particular illustration shown in Figs. la, 1b and lc, when the bore 14x is plugged against fluid passage, most of the tubing string can then be removed from the well by unlatching the tubing string from thel packer at the releasable tubing joint `1--2. A sudden lowering 0f the tubing string will snap the frangible screw 1a and permit lowering of the mandrel 2 within the receptacle l. When so lowered, the tubing string can be rotated counterclockwise as viewed from above so as to disengage the pin 2c from the bayonet joint 1f and thereby permit upward withdrawal of the tubing string including the hollow mandrel 2. The receptacle 1, the packer 3 and the lower portion of the tubing string including the valve tube 14 and sub 16 will remain in the well, and migration of fluid from one side of the packer to the other side `can be prevented by said valve plugs 17 and 18.

'Ihe bore-closing tool of the present invention can' be used for a number of other purposes than that described with respect to Figs. la, lb and 1c. However, the use of the tool in conjunction with the packer and a releasable tubing joint greatly facilitates perforation or other treatment of the upper `zone of a dual-completion well. The present tool was designed particularly for the purpose of taking advantage of differential pressures on opposite sides of the valve tube whereby the valve plugsv may be shifted up and downtherewithin without opening the bore to flow in either direction. Such shifting up and down prevents sticking, or dislodges valves which are already stuck so as to greatly facilitate removal thereof from the Vbore and reopening of the bore to fluid circulation. i

I do not limit my invention to the exact form shown in the drawing for obviously changes may be made therein within the scope of the following claims.

I claim:

1. A tool for insertion in a tubing string conducting luids within its bore, said tool comprising an elongated valve tube having connection means at each end for connecting the tube in series with adjacent ends of the tubing string, and said tube having a bore therethrough communicating withsaid tubing bore; a valve seat at each end of the valve tube bore, said seats facing in mutually opposite directions; an upper valve plug having a stem adapted to enter the tube bore and having a valve shoulder above the stem; and a lower valve plug having a stem adapted to enter the tube bore and having a valve shoulder below the stem, and said lower plug having resilient sealing means around the stem above the shoulder, the distance between the valve shoulders when the plugs are touching each other within the tube bore being greater than the distance between said seats on the valve tube.

2. In apparatus as set forth in claim l, said upper plug having resilient sealing means around its stern below its shoulder and the distance between the sealing means on one plug and the shoulder on the other plug when the plugs are touching each other in the valve tube bore being less than the distance between said seats.

3. In apparatus as set forth in claim 2, said sealing means comprising annular resilient seals having cupshaped cross sections, and said seals facing upwardly on the upper plug and downwardly on the lower plug.

4. In apparatus as set forth in claim l, the sealing means Von the lower valve plug stem being wholly within the valve tube bore when the plugs are touching each other therein and the shoulder on the upper plug is engaged with the upper seat.

5. In apparatus as set forth in claim l, a fishing head at the upper end of each of said plugs.

6. In apparatus as set forth in claim l, the lower end of said valve tube being connected with a tubing sub, and said tubing sub having a bore and having an obstruction in said bore to prevent ltravel of the lower plug therepast, said obstruction being spaced below the upper end of the sub by a distance greater than the overall lengh of the lower plug.

' 7. In apparatus as set forth in claim 6, the wall of said sub being perforated along a portion of its length between its upper end and said obstruction.

8. For use in a well containing fluids, the combination of a packer having means for anchoring it in said well, and said packer having a bore extending axially therethrough; a tubing string in the well and communicating with said packer bore to form a continuous passage; and a tool for closing said passage to prevent ow of fluids therethrough, said tool comprising an elongated valve tube having connection means at each end for connecting the tube in series with said tubing string, said valve tube having a bore therethrough communicating with said tubing bore, a valve seat at each end of the tube bore, said seats facing in mutually opposite directions, an upper valve plug having a stern adapted to enter the valve tube and having a valve shoulder above the stem, and a lower valve plug having a stern adapted to enter the valve tube bore and having a shoulder below the stem, said lower plug having resilient sealing means around its stem above the shoulder, the distance between the valve shoulders when the plugs are touching each other within the valve tool bore being greater than the distance between said seats on the valve-tube.

9. In apparatus as set forth in claim 8, said upper plug having resilient sealing means around its stem below its shoulder and the distance between the sealing means on one plug and the shoulder on the other plug when the plugs are touching each other in the valve tube bore being less than the distance between said seats.

1-0. In apparatus as set forth in claim 8, the sealing means on the lower valve plug stem being wholly within the valve tube bore when the plugs are touching each other therein and the shoulder on the upper plug is en'- gaged with the upper seat.

l1. In apparatus as set forth in claim 8, a fishing head at the upper end of each of said plugs.

12. In apparatus as set forth in claim 8, the lower end of said valve tube being connected with a tubing sub, and said tubing sub having a bore and having an obstruction in said bore to prevent travel of the lower plug therepast, said obstruction being spaced below the upper end of the sub by a distance greater than the overall length of the lower plug.

13. In apparatus as set forth in claim l2, the wall of said sub being perforated along a portion of its length between its upper end and said obstruction.

14. For use in a well containing fluids, the combination of a packer having means for anchoring it in said well and said packer having a bore extending axially therethrough; a tubing string in the well andcommunicating with said packer bore to form a continuous passage; a joint in said tubing string above the packer and having releasable sealing means permitting detaching of the portion of the tubing string above the packer; and a tool for closing said passage at a location below said joint to prevent flow of fluids therethrough, said tool comprising an elongated valve tube having connection means at each end for connecting the tube in series with the portion of the tubing string below the joint, said valve tube having a bore therethrough communicating with said tubing bore, a valve seat at each end of the valve tube bore, said seats facing in mutually opposite directions, an upper valve plug having a stern adapted to enter the valve tube and having a valve shoulder above the stem, and a lower valve plug having a stem adapted to enter the valve tube bore and having a valve shoulder below the stem, and said lower plug having resilient sealing means around its stem above the shoulder, the distance betweenthe valve shoulders when the plugs are touching each other within the valve tube bore being greater than the distance between said seatson the valve tube.

15. In apparatus as set forth in claim 14, said upper plug having resilient sealing means around its stem below its shoulder and the distance between the sealing means on one plug and the shoulder on the other plug when the plugs are touching each other in the valve tube bore being less than the distance between said seats.

16. In apparatus as set forth in claim 14, the sealing means on the lower valve plug stem being wholly within the valve tube bore when the plugs are touching each other therein and the shoulder on the upper plug is engaged with the upper seat.

17. In apparatus as set forth in claim 14, a fishing head at the upper end of each of said plugs.

18. In apparatus as set forth in claim 14, the lower end of said valve being connected with a tubing sub, and said tubing sub having a bore and having an obstruction in said bore to prevent travel of the lower plug therepast, said obstruction being spaced below the upper end of the sub by a distance greater than the overall length of the lower plug.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,076 Otis et al. Feb. 29, 1944 2,384,192 Otis et al. Sept. 4, 1945 tpm,

t. wer-hv

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2343076 *Feb 13, 1941Feb 29, 1944OtisWell apparatus
US2384192 *Aug 26, 1940Sep 4, 1945OtisWell packer and apparatus for producing wells
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5893415 *Feb 20, 1997Apr 13, 1999T-Rex Technology, Inc.Gas diversion tool
US6009945 *Nov 10, 1997Jan 4, 2000T-Rex Technology, Inc.Oil well tool
US7350578Nov 1, 2005Apr 1, 2008Halliburton Energy Services, Inc.Diverter plugs for use in well bores and associated methods of use
US7506686 *Nov 1, 2005Mar 24, 2009Halliburton Energy Services, Inc.Diverter plugs for use in well bores and associated methods of use
US7559363Jan 5, 2007Jul 14, 2009Halliburton Energy Services, Inc.Wiper darts for subterranean operations
US7665520Dec 22, 2006Feb 23, 2010Halliburton Energy Services, Inc.Multiple bottom plugs for cementing operations
Classifications
U.S. Classification166/320, 166/142
International ClassificationE21B34/00, E21B34/06
Cooperative ClassificationE21B34/06
European ClassificationE21B34/06