CA1170163A - Apparatus for chemical cutting - Google Patents
Apparatus for chemical cuttingInfo
- Publication number
- CA1170163A CA1170163A CA000408332A CA408332A CA1170163A CA 1170163 A CA1170163 A CA 1170163A CA 000408332 A CA000408332 A CA 000408332A CA 408332 A CA408332 A CA 408332A CA 1170163 A CA1170163 A CA 1170163A
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- Prior art keywords
- tool
- fluid
- slip
- slips
- cutting
- Prior art date
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Abstract
APPARATUS
FOR CHEMICAL CUTTING
ABSTRACT OF THE DISCLOSURE
A method and apparatus for cutting tubing suspended in a borehole. An elongated tubular assembly is provided for suspension in and securement within a wellbore for the chemical cutting of the tubing therein through the discharge of high velocity streams of a highly reactive, incendiary chemical fluid. The apparatus includes the storage of a halogen flouride, or the like, disposed within a chemical module inter-mediately disposed of propellant and slip assembly modules and a discharge head assembly. The propellant module is constructed with a chamber containing active burning ignition powder for igniting a slow burning propellant for the generation of gas to pressurize the chamber and cause a linear actuation of the slip assembly responsive thereto for the deployment of a cylindrically segmented slip array to securely engage the adjacent tubing and anchor the apparatus therein. The generation of the pressurizing gas also imparts a movement of the in-cendiary fluid through a catalyst chamber for causing the fluid to react and discharge through the discharge head assembly for the cutting of the adjacent tubing. The slip assembly is constructed with a dual taper, gripping teeth configuration for matingly engaging two discrete tubing dia-meters, therein facilitating interchangeable use within conduit of different sizes. The assembly also includes a pair of rupture diaphragms enclosing the incendiary fluid, which rupture to a substantially full flow opening at a preselected breakthrough pressure to facilitate effective and safe oper-ation of the present invention.
FOR CHEMICAL CUTTING
ABSTRACT OF THE DISCLOSURE
A method and apparatus for cutting tubing suspended in a borehole. An elongated tubular assembly is provided for suspension in and securement within a wellbore for the chemical cutting of the tubing therein through the discharge of high velocity streams of a highly reactive, incendiary chemical fluid. The apparatus includes the storage of a halogen flouride, or the like, disposed within a chemical module inter-mediately disposed of propellant and slip assembly modules and a discharge head assembly. The propellant module is constructed with a chamber containing active burning ignition powder for igniting a slow burning propellant for the generation of gas to pressurize the chamber and cause a linear actuation of the slip assembly responsive thereto for the deployment of a cylindrically segmented slip array to securely engage the adjacent tubing and anchor the apparatus therein. The generation of the pressurizing gas also imparts a movement of the in-cendiary fluid through a catalyst chamber for causing the fluid to react and discharge through the discharge head assembly for the cutting of the adjacent tubing. The slip assembly is constructed with a dual taper, gripping teeth configuration for matingly engaging two discrete tubing dia-meters, therein facilitating interchangeable use within conduit of different sizes. The assembly also includes a pair of rupture diaphragms enclosing the incendiary fluid, which rupture to a substantially full flow opening at a preselected breakthrough pressure to facilitate effective and safe oper-ation of the present invention.
Description
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BACKGP~OI~D OF THE INVENTION
This invention relates to a method of and apparatus for cutting tubing, and, more particularly, to a system employing a chemical cutting fluid of highly reactive incendiary character such that when brought into contact with tubing suspended in a wellbore, it will quickly burn therethrough. The term "cutting" is used herein as a generic term to include cutting, severing, perforating or slotting of tubing and other objects, as well as their complete disintegration. The objects referred to may be metal pipe or wellbore lining, including the earth formation surrounding or forming the wall of the wellbore or extraneous foreign objects such as lost drilling tools suspended therein. Prior apparatus for cutting tubing are commonly referred to simply as "tubing cutters". Such cutters are used, for example, in drilling operations wherP it is desired to detach a bullplug or other obstruction from the lower end of a tubing in a wellbore by severing the tubing above the bullplug.
Tubing cutters are also used to salvage the tubing from an abandoned well or the part of the tubing above a stuck point.
There are various types of prior art tubing cutters, for example, shaped charged cutters and chemical cutters. There are problems associated with shaped charge cutters, however, because a tubing string into which the cutter can be lowered into the wellbore, oEten contains a pump seating nipple or landing nipple which foxms a partial constriction in the tubing by reducing the size of the bore. This landing nipple may be located at a point intermediate the surface and the part of the tubing to be cut. In tubing cutters which are constructed I `~ 0 ~ ~ 3 to'b~ part,ially recovered, tlle force ~c,~n~rated b~ an ~xplosion of a shapecl charge in the tubin~ cutter causes parts of the cutter which are not disintegrated to becorne expanded or the end of the tubing to become flared. This expansion oEten times prevents the retxieval of the expanded part.
Chemical cutters have been shown to be very reliable whi le overcoming many of the aforesaid problems. They have been referred to as the simplest and most efficient tool for tubing cutting because the cut is made without flare, debris or 10, damage to the adjacent string of tubing. One such prior art construction is shown and described in U. S. Pats. 2,918,]25, ¦ issued Decernber 22, 1959 and 3,07G,507, issued Februar~ 5, 1 1963, both to William G. Sweetma~ s set forth in the ¦ Sweetman Patents, the cutting fluids employed in accordance ,I with that invention are fluids which are extremely active chem-ically and which when brought into contact with most oxi-dizable substances, react violently therewith generating ex-tremely high temperatures sufficient to melt, cut or burn -the adjacent tubing. Fluids such as halocJenflourides, ineluding cholorine tri-flouride as well as bromine tri-flouride, have j been proven to be effeetive in tubing cutting.
There are several considerations which remain of major ¦l import in the utilization of such chemical cutters as set forth Ij above. First, the secure anchoring, or downhole positioning j of the cutter within the wellbore i5 a major consideration. The cutter must be fixedly positioned within the wellbore so as i to make a uniform cut and to prevent the flaring or creation ;
I I ~O~ G3 of deb.ris within the wellhore to :Erustrate the attempt of an effective cutting operation. ~he ricJidity of the anchoring and centralized positioning is thus oE critical import. It is ¦ also necessary that the overall unit be functionally reliable, ¦ including sure igni-tion, positive fluid seals and cnvironmental ~¦ durability. ~or example, the insertion of the -tool into -the ¦~ wellbore is coincident with immersion in those ~luids normally present therein such as mud and sand. It is -thus important that ¦
~¦ sueh substances do not adversely affect -the operation oE the subject -tooling.
It would be an advantage therefore to provide a chemical tubing eutter which would overcome many of the problems of the . prior art wherein the tubing cutter could be reliab].y and ¦ securely positioned within the wellbore for the cut-ting oper-11 ation. It woul~l be a further advantage to provide a single ¦I tubing cutter seeurable within known conduits of a differen-t jl size while effecting the equivalent reliability. The method and 1~ apparatus of the present invention includes such a chemical j¦ tubing cutter wherein a multi-àngulated slip assembly is utilized 20 1I for circumferential engagement within tubirlg of different sizes.
The tubing cutter of the present invention also provides a means for the reliable sealing, ignition and actuation of the in- j cendiary elements therein for the proper maintenance and control ~l, thereof.
1! SUMMARY OF THE INVENTION
! The invention relates to a chemical cuttinc~ method and ¦ apparatus including a tubular array containing means for I
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IJ~(~16~3 central.ly securinCJ ltse,lf in a borchole ancl CUttinCJ the tubing therearound wi.th an incendiary chem:ical fluid. r~ore par-ticularly, one aspec-t of the invention includes the incendiary chemical fluid of a halocJen flouride dlsposed within a chemical module intermediate of a propellant and slip assembly module l array and a discharge head assembly. The chemical is caused to ¦¦ be discharged in one or more high veloci.-ty streams, or ~,ets, by applying to the body ol the fluid a suitab]e compressible ¦ pressurizing medium of adequate magnitude. The pressurizincJ
:1.0 I medium is a gas generated by the igni-tion ancl regular burning ¦ of one of various types of relatively slow burni.ng propellants.
¦¦ By uti].izing an electrical composition resistor as an ignition ¦ element, the iynition of the propellant may be more effectively Il and safely controlled to generate the gas at a predetermi.ned ¦I time suitable for the particular application and the desired I pressurizing force confined within the body oE the cutting ~ ,U~.t~
fluid. Furthermore, a ~r~c~ible.,..rupturable~diaphragm is utilizec .
to store said fluid wherein the diaphragrn is selectively formed I to rupture within a narrow range of di.fferential fluid pressure ','0 1l to obtain buildup of the desired pressurizing force before the ¦¦ cutting fluid is activiated.
In another aspect of the invention, the slip assembly j i.s provided in a cylindrically segmented array comprising a plurality of arcuate, tubing engaging elements assembled cir- ¦
~5 I cumferentially about -the sli.p assembly modu].e substan-tially , therearound. The array is adapted for the outward deployment thereof for engaging the maximum surface area of the tubing thereabout in predefined secured engagement patterns. ~ach slip li .
`` 1~7~3 .~ elemen-t includes an elongated section of arcuate cross-sectional confi~urati.on having laterally e~tenclin~,~-tu~inq engagement edyes constructed thereacross in generally parallel sp~ce rela-tionship, longitudinally therealong. X'he la-teral eclyes, or teetil of each I slip are furthermore constructecl iSl -two discxete, longi,-tudinal ¦ angulation configurations complimentally designed to engage two I distinct diameters of tubing acljacent thereto, uniformly -there-¦¦ along, and centrally therein.
Ii In yet another aspect, the s],ips are constructed and ¦ll assembled whereby the longltudinal edc;es thereof in the undeployed ¦¦ mode generally cireumferentially encompass -the entire circum-¦ ferenee of the underlying slip assembly region adjacent thereto ¦ for providing maximum utilization of surface area of the slip ¦¦ assembly for engaging -the adjaeent tubi.ng therearound. In ll this manner, maximum strength and anchoring may be effected ! within the wellbore.
BRIEF DE CRIPTION OF TE~E DRAWINGS
ll For a more complete understancling of the present inven-¦l tion and for further objects and advantages thereof, referenee ¦¦ may now be had to the following descripti.on taken in conjunc- ¦
tion with t,he accompanying drawings, in which:
ii FIGS. 1 through 5, together, comprise a longitudinal, eross-seetional, side-elevational view of one embodiment of a Il ehemical cutting apparatus eonstrueted in aeeordanee with the ?.5 1I prineiples of the present invention, illustrating an array of propellant, ehemical, slip and discharge head modules in end-to-end relation;
FIG. 6 is a top plan, cross-sectional view of the inter-mediate portion of the tubing cut-ter assembly of FIGo 3 taken along lines 6-6 thereof and lllustratina tbe cylindrically 11 .
1 '~
segmentecl grippirlg slips assembled -therearollnd;
F[~. 7 is an enlarged, side-el.eva-tional view of an in-, dividual slip from the s].ip array of FIG. 3, illustrati.ng -the ¦ gripping tee-~h formed with two discrete angulation pat-terns;
1. FIG. 8.is a fragmentary side-elevational, cross-sec-tional view of a slip assembly in an outwardly deployed configu-ration engacJing -the side wall of tubin~ in a borehole;
FIG. 9 is an enlargecl top plan view of a rupture dia-¦¦ phragm of the chemical module of FI~
l FIG. 10 is a side-elevational, cross-sectional view of ¦ the rupture diaphragm of FIG. 9, takerl along li.nes 10-10 ¦I thereof;
FIG. 11 is an enlarged perspective view of a rupture !i diaphragm illustrating the ruptured configuration thereof for ¦¦ providing a substantially full Elow opening; and ¦I FIGS. 12 and 13 comprise a longitudinal, cross-secti.onal side-elevational view o:E an alternative embodiment of the slip assembly module of the present inventi.on.
DETAILED ~ESCRIPTION
¦ Referring first to E`IGS. 1 -through S, there is shown a cutting tool designated generally by the number 10, which is l inserted in a strin~ of tubing (not ShOWII) extending into a ¦ wellbore which may be lined with a metal casing (not shown).
I The cutting tool cornprises in downwardly arranged succession, a ¦ propellant module assembly 12, a slip a.ssembly 14, a chemical ¦I module assembly 16, and a discharge heacl assembly 18. These ~¦ several modules, which are constructed of suitably strong mater.ial such as steel, are generally cylindrical and connected 1~70163 ¦ together i.n end-to-end coaxial rela-tion. The modular array ¦ forms an elongated cylindrical tool 10 o~ substantially uniform ¦ exterior diameter, which is adapted for insertion into -the I tubing string on the end of a fl,exible cable, or the like (not S ~ shown). A head assembly 2n, is connected to the upper end of I the cutting tool 10 and includes a socket 22 of generall~ con-¦¦ ventional form which connects the upper end'of the tool 10 to the tool string or cable which is employed for l.owerincJ and . j raising said tool in the wellbore. The aforesaid tool stri,ng :lO , or cable, al-though not shown, includcs means for transmitting ¦ an electric current from a conventional source about the well-l bore to the tool 10 for the operation thereof.
Referring particularly now to FIG. ]. there is shown the propellant module assembly 12 disposed beneath and secured to 1.5 the head assembly 20. In-terconnecting the head ~ssembly 20 I and the propellant assembly 12 is a firing sub 24 containing an ¦ electrode 26 centrally therethrough insulated within a dielectric ! sleeve 28 therearound. A mating interconnection element, or ¦¦ plug 30 is construc-ted atop the electrode 26 for electrical ~0 ¦¦ communication with the surface above the borehole. Immediately ~l, beneath the elcctrode 26 and the firing suh 24, ~here depends ¦l a fuse assembly 32 including a}l exp].osive initiator element Il 34 of generally conventional design. The fuse assembly 32 being ¦
¦¦ placed in electri.cal contact wi-th the end of the electrode 26 ,,¦ provides means for igniting a controlled burning propellant disposed therebelow. ~ longitudinal passage 36 provides com-~¦ munication between the initiator cap 34 and a propellant chamber ¦ 37 formed in the propellant module assemb].y 12. The modu1e I~ -8-I J ~O l6 ':~
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I
12 includes an outer sleeve 3~ couplecl to the fuse assembly v:ia a threaded coupliny 40. It should be noted that the various modules and suhassemblies describeti here~in, are conventionally coupled one to the o-ther by -threaded couplincJs and sealed with O-rings positioned therewithin. The -threaded couplings and O-rings are no-t numbered but are clearly illustrated as is con~
ventional in the art. The passage 36 terminates into a central bore 44 forming the chamber 37 and con-taining a propellant housing, or spacer 46 having a plurality of ports 48 formed along the length thereof. The propellan-t spacer 46 contains a pluralit~
of power pellets 50 stacked therein or an integral propellant grain (not shown) and adapted for being ignited by the fuse assembly 32 disposed thereabove for the generation of a pro-pellant gas.
¦ Referring now to FIG. 2, there is shown the lower part of the propellant assembly 12 and particularly the lower region of the power charge sleeve 46 containing the propellant therein.
sui-table annular region may be provided around the propellant spacer 46 and within the tubular bore 44 of tht-~ propellant chamber 37 as shown for the generation of suitable pressuri~ing gases therein. The gases generated in -the propellant assembly 12 are allowed to escape downwardly into -the lower slip assembly 14 for actua-tion thereof via a tubular bore 52 constructed beneath the propellant chamber 37 in an upper region of the slip il assembly 14 comprising an upper slip sub 54. The slip sub 54 is threadably coupled to a central slip shaft 56 depending therefrom. The slip shaft 56 comprises the~ structural center of the slip assembly 1~ and includes a central bore 58 formed Il ~1 _9_ ~1 .
1170~63 thercthrough in a~uttlng oommunication wlth the slip sub I passage 52 for permit-ting the propellant gases to esca~e there-¦ through.
¦ Referring now -to the lower region of the tool 10 ¦ illustrated in FIG. 2, there is shown a cylindric,al housing 62 with the slip shaft 56 received therein. A longitudinal compression spring 60 is provided within the slip assembly housing 62 within a central space 6~ formed tllerein. 'i`he spring . 60 circumferentially encompasses the slip shaEt 56 longitudinally 1¦ therealong longitudinally biasing the sli.p housing 62 upwardly ! against the upper slip sub 5~.
Referring now to FIG. 3, there i.s shown in the upper region thereof, the lower section of the slip assembly module j 14 of the cutting tool 10. The slip shaft 58 rnay be seen to ¦ include a lower seating flange 66 for receiving the base o~ the spring 60 thereagainst. The flange 66 inclues a circumferen-j tial slotted portion 68 containing an O-ring 70 therci.n for j purposes of sealing the slip shaft 56 rela-tive to -the slip ¦¦ housing 62. A piston-cylinder configuration is thus constructed I between the slip shaft 56 and slip assembly housing 62 respec-¦ tively. ~eneath the flange or piston 66 the central passage 58, extending through the slip shaft 56, is vented through venting ports 72 extending transversely therefrom and in communication with the passage 58 for venting a lower, annular space 7~ beneath the flange 66. The slip housing 62 is constructed w~th a lower . ¦ flange bulkhead 76 containing an O-ring 78 therewi-thin and around the slip hafC 56 Eor seeling the said housing ther~against.
ll 1 :~7~63 I In this manner, propellant gases escapincJ through the passage 58 will he vented into the annular space 74 for ~reating a pressure agains-t the seating flange 66 and causincJ -the slip ~ assembly housing 62 to be driven downwardly alon~J the slip ¦ shaft 56, a~ainst the biasing compression of the spring 60.
Referriny now to the lower region of FIG. 3, there is l shown the lower portion of the slip assembly housing 62 con-structed with a partially open-ended annulus 80 constructed j therein. A lower con-trally aperture flange 82 forms the base 1ll portion of th~ annulus 80 and receives the upper head section 84 of an array 85 of gripping slips 86 pivo-tally seated therein about the slip shaft 56. The gripping slips 86 are constructed ¦I with a plurality of gripping teeth 88 on the outer surface ¦I thereof. The teeth 88 are adapted to engage and secure]y grip 1- 1¦ the wall of adjacent tubing as will be described in more detail below.
ll A plurality of slips are provided around the slip-¦l shaft 56, each being constructed with a lower, internally ¦¦ tapered end 90. The end 90 of each 51i.p 86 is adapted for ¦1 abutting a complementally tapered frusto-conical mandrell 92 ¦l of a lower slip sub 94. The mandrel 92 functions as an incline ¦ plane for the slips 86 as -they are driven downwardly with the I slip assembly housing 62 in response -to the generation of ¦I propellant gases within the propellant module 12. The downward ,¦ movement of the slips 86 over the mandrel 92 causes the outward, 'I angular dep]oyment of the slips 86 for anchorin~ against the adjacent tubing. The slipshaft 56 may be seen to be struc-turally interconnscted with ~ lower slip sub 4 through a ~ -~ 5 3 threaded lnterco~ ection therebetween. Sprillg means 96 such as "garter springs" are provided around the slips ~6 through a slotted por-tion 100 forrned above the teeth 88. The sl?ring means 96 may include any suitable elas-tic material or spring ¦ construction sufficient to lightly bias the slips 86 in the closed position shown.
Referring now to FIG. ~, there is shown the lowermost portion of the slip assernbly module :l4 wherein the passage 58 ll of the slipshaft 56 cornrnunicates with a central bore 102 formed ! within the lower slip sub 9~. The bore 102 comprises a passage l¦ for the egress of propellant gases from the passage 58 into the ¦1 lower chemical module 16. The chemica:L module 16 is connected ¦¦ to the slip assembly rnodule through a scaled interconnection jl 104, wherein means are constructed for sealably containing the 1, select incendiary fluid stored in said chemical module.
¦ll gasket 106 is thus provided beneath the passage 102 atop a !i diaphragm retainer 108 abutting a rupture diaphragm 110. The ¦ diaphragm 110 is constructed with an area of reduced cross-j section for rupturing at a predefined fluid pressure dif~eren-~0 , tial thereacross in a manner ~o comp:Letely open the flow passage therethrough as will be described in more detail below. The diaphragm 110 seals a fluid chamber 112 centra]ly bored within the chemical module 16 therein con-taining a selected incendiary ! fluid 111. The term incencliary chernical is used herein as I referring to a higllly reactive chemical which is particularly ¦ adapted for such downhole cutting operation. In particular, bromine tri-flouride has been found to be acceptable as an . 1~70~
¦ incendiary fluid for cuttiny operat:i.ons i.n accordance with the I teachings o~ the present lnvention. The aEoresaid incend.iary ¦ fluid is fur-ther contained within the chamber 112 by a lower ¦ rupture diaphragm 110. Likewise, a cliaphragm retainer 116 and j gasket 118 are provided therebeneath Eor the securement and sealin~ of the diaphragm 110 thereabove.
Compressed propellant gas generated in -the propellant ¦ module 12 acts in a select manner and at a select pressure to ¦ cause the rupturing of the rupture diaphragm 110, forcing the :L0 ! incendiary fluid 111 within chamber 112 downwardly, rupturing ¦ the lower rupture disc 110 for passage in-to an igniter sub 120 partially housing within the chemical module assembly 16.
The ignitor sub 120 is threadably coupled -to -the chemical I module 16 and is construated with a central chamber 122 con-lS 1¦ taining steel wool 123 which ma~ be coated with oil, or a Il similar product suitable for reaction wi.th the respective in-cendiary fluid utilized. The steel woo]. 123 promotes a violent reaction when it contacts the downwardly egressing incendiary ¦ fluid 111 for the generation of further pressure and activity.
¦l A lower longitudi.nal passage 124 is constructed benea-th the ¦I chamber 122 in communication therewith :Eor the escape of the activa-ted incendiar~ fluid 111.
ll Referring now to FIG. 5, there is shown the lower por-¦l tion of the igniter sub 120 and the passage 124 ex-tending there-1I through and communicating with a discharge head piston 126 i positioned within the discharge head module 1~. The piston ' 126 is slidably mounted within an axial bore 126 constructed !
il within the discharge head housing 129, which is .~ormecl with a I plurality oE radially extending ventin~ ports or jets 130 extending outwardly o the central bore 128. The piston ].26 is l mounted within the bore 12~ for downward movement ar-d ~s suitably sealed therein with a plurality of smaller O-rinys 132 secured therearound both above and belo~J the discharge ports 130.
Proper sealing of the piston is necessary to ensuxe the noncon-¦ tamination of the tool 10 from well flui.ds during insertion I within a wellbore.
! The discharge head module 18 includes a lower bullnose 134 depending from and threadably coupl~d to the housing 129.
The bullnose 134 forms the lower encl of the tool 10. The bull~
nose is comprised oE a ~enerally cylindrical section having I axial bore 136 constructed for receiving the piston 126 once ¦ said piston is driven downwardly by the pressure oE the pro-pellant and fluid generated thereabove.
The bullnosel34 is coupled to the discharc3e head housing jj 129 with a support washer 138 lodged therebetween. The suppor~
¦¦ washer 13~ is constructed with a central aperture 1~0 having - 20 11 a diameter small enough to retain the piston 126 thereabove.
~¦ The washer 138 is also constructed oE sufficiently thin material to deform and/or shear under preselected forces to permit Il the downward movement of the pistOIl 126 under pressure of the ¦ escaping incendiary fluid 111. The downward movement of the ¦. piston 126 into the chamber 136 of the bullnose 13~ opens the chamber 128 to the discharge ports 130, permi-t-ting the incen-diary fluid 111 to jet therethrough. The discharge ports 130 are constructcd in a radially extending pat-tern (not shown), - il . I
1 17t~163 which pattern is of convenl:iona]. "overlap" design. Arl "overlap"
pattern is one wherein flui-l spray of adjacent discharge ports is contiguous upon -the surface being cut so tha-t the incen-diary fluid discharged from said adjacent ports forms a sub-S ¦Istantially con-tinuous cut pattern.
Referring now to FIG. 6, there is shown a top plan vie~
of the slip assembly 14 of FIC7. 3 taken along lines 6-6 thereoF
and more clearly illustrating the positi.oning of the slips 86 . ¦thexealong. In the tool 10 of the present embodiment, six slips 186 are provided to comprise a generally cylindrical array, segmented one from the other and constructed for outward deploy-ment from the slip shaft 56. The terrn "cylindrically segmen-ted"
is hereinaft~r utilizeA in referring to the particular slip llassembly array 85 of the present invention. The cylindrically Ij segmented slip assembly 85 is constructed whereby inner surface area of the slips 86 substantially encompasses the slip shaft 56 therebeneath in a generally cylindrical, segmented housin~
¦confic3uration. It should be noted that the assembly of the slips 86 into the array 85 requires a "keyed" subassembly into the lannulus 80 (FIG. 3). With the shaft 56 removed, the slips 86 ¦are inserted into the annulus 80 and keyed together. The shaft 58 is then inserted to effec-t an assembly wherein the slips 86 are locked into place, one against the other. The outward l deployment of the slips 86, wi-th the head sections 84 pivotiny ¦¦ within the annulus 90, then permits engagement of the adjacent ¦ tubing with maximum gripping effectiveness for secure anchoring thereagainst. Additionally, the segmente~, cylindrical con-~figuration of the slips array 86 ensures the centralization of I
il -15-~1 1170~3 the tubing cutter 10 w:ithin the wellhore since each slip deploys in a direction opposite to that of an opposing slip, an equivalent distance, automatically centralizing the position of the tool l 10. Certain prior art constructions have heretofore utilized gripping slips having grippin~ teeth inscribed upon the outer Isurface thereof; however, such slips have no-t been provided i.n ¦the segmented cyli.ndrical array provided herein and in -the ¦gripping teeth angulation pat-terns facilitatin~ multidiameter . applications as discussed below.
¦ ReEerring now to FIG. 7, there is shown a longitudinal, l cross-sectional elevation of a slip 86 wherein the gripping j¦teeth 88 formed upon the outer surface thereoE may be seen in j'more detail. It should be noted that the gripping teeth 88 I! of the particular embodiment shown herein are provided in two 1I discrete angulation patterns. These patterns are illustrated : Iby the phantom lines 150 and 152 drawn on the surface of the gripping slip 86. ~he phantom line 150 illustrates a first angulation pattern for gripping ~eeth 88 formed on the upper half of the slip 86. The particul.ar construction anyle of the ~ 20 Iteeth 88 below line 150 is adapted for uniformly engaging an : ladjacent tubing wall of a certain diameter upon deployment of the ~ Isubject slips. Each slip 86 engages the adjacent tubiny with :~ 'equivalent surface area engagement and pressure, due to the Icentralizing effect of the segmented cylindrical array 85 of the jslip assembly 1~. The angulation pattern defined by the phantom line lS0 may be designed for a particular deployment an~le ¦lequivalent to a particular tubing diameter.
Il .
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~ l I l 7~3 Stil.1 referring to FIG. 7, phantom ~ e 152 illustrates ¦ a second grippi.ng teeth angulat:ion pattern of less acute I construction relative to the centrcll .lXiS o the sl.ip shaft 56.
¦ In this manner, the slip 86 may be deployed at a grea-ter angJ.e ¦ than provided for by said first angulati.on pattern -to uniformly ¦ engage a tubing wall of larger diameter.
Referrlllg now to FIG. 8, there is ShOWIl an example of the aforesaid flrs-t and second anc;ulation patterns irl engagement with a tubing wall and illustra-ted in exaggerated form. The upper gripping teeth 88 beneath the phantom line 150 are shown to be left unengaging the adjacent tubing 155 since the slip 86 shown thereln is deployed at the select angle for anchorirlg tubing of a second larger diameter. It may be seen that if the l tubing 155 were of a smaller select diameter, the upper section 1 of the gripping teeth 88 would engage said tubing with the lower teeth, beneath phantom line 152 left unengaged. In -this rnanner, I a single cutting -tool 10 may be utili~ed in boreholes of more ¦ than one diameter for cutting operations therein.
j! ReEerring now to FIGS. 12 and 13 there is shown a ¦, slightly different embodimen-t of slip assembly 1~. As readily ¦~ noted, in these drawings, slip assembly 1~ is virtually the ¦I same construction as shown in FIGS. 2 and 3 except it is mounted in an inverted relationship top to bo-ttom in the cutting -tool I 10. It may also be seen that the profile of slip 86 and in ¦ particular -the gripping teeth 88 is slightly modified relative ! to the proEile shown in l;~IG. 3. ~ccordingly, li]ce elements ¦ oE the slip assembly 1~ as shown in EIIGS. 2, 3, 7 and 8 bear the same numbers as the elements shown in FIGS. 12 and 13.
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i~ 117~)~63 ¦ The operatlon of the sLip assembly 14 as shown in FIGS.
¦ 2 and 3 is as follows: The gas pressure i.n space 72 causes the slips to engage the well tubing 155 in which tool 10 is positione~
and therein holdin~ the tool 10 immobi:le until all the liquid reactive chemical is ejected through the ventiny ports, or jets, 130 and until the gas pressure is dissipated by egressillg behi.nd said liquid through said venting ports. As previously descri,bed, after the gas pressure has dissipated, the sprin~ 60 is provided to retract the s.lip assembly 85 away from the walls o t~le tubing L0 ¦ 155 into its ini-tial retracted position. However, for some reason should spring 60 not allow the slip assembly 85 to de-tract, it would be difficult to disengage the slip 86 from the tubing 155. The only possible mechanical mani~ulation in suc:h a position would be through the cable .Erom which cutting tool 10 is suspended. The only Eeasible manner oE disengacJement in this instanc~ is to impart a downward jarring for the tool. I
10. Wireline jars are available for this purpo.se but are expen~ ¦
sive and a nuisance to use. It may thus be seen tha-t in the embodiment of FIGS. 12 and 13, if spring 60 fails to disengage ¦ slip assembly 85, a tension applied by upward pull on the wire-¦l '.ine will draw the conical mandrel 92 out :Erom under the slips ~! 86 quite readily for fa_ilitating removal of the cutting tool 10 from tubing 155.
I¦ At times, the slip retaining means 100 may be damaged 1¦ or destroyed by flow of the incendiary fluid past assembly 14.
¦l In the situation of FIGS. 2 and 3, such happening is of little I consequence since the slips 86 tend to pivot inwardly when il Il -18-I ~ 70163 cutting tool 10 is pulled upwardly. However, the reverse is ¦1 evident in the situation of FIGS. 1.2 and 13. ':['o alleviate hang-up problems in the tubing, slip ~6 o.E this particular ernbodiment l is provided with a bevel or chamfer 170 as shown. Bevel. 170 allows each slip a6 -to slide along the tubing wall in "sled"
fashion if slip retaining means 100 becomes inoperable alld fails to retract the slip. The grippinc3 teeth 88 are also shown with a slight variation in -the l~rofile thereof. As shown in FI~
7, the gripping tee-th 88 are of a "buttress" proEile slanting ~0 ~ upwardly. In this alternate embodiment the teeth 88 are of e~ual sided of "V" shape with -the included angle of the apex of -the "V" being about 50-90~. This slip tooth profile is considered superior in some respects in that it may be dis-1l engaged from embedment in the tubing more easily and also because i5 ¦¦ it also remains firmly engaged by thepiston 66 un-til the pro-¦~ pellant gas pressure is dissipated through the jets 130 following evacuation of the incendiary chemical fluid. This slip also ¦ is of dual construction angle as shown by lines 150 and 152 of l FIG. 7 shown in FIG. 8.
` ~eferring now to FIG. 9, there is shown a top plan view of the rupture diaphragm 110. The diaphragm 110 includes an area of reduced cross-section 160 constructed by stamping, Il cutt~ng or similar fabrication technique. The area 160 effec-¦l tively ensures the rupture of the di.aphragm at a closely pre--1I selected differential fluid pressure which is an impor-tant ¦I safety and reliability parameter. The pattern of the area of reduced ~ross-sec~ion 160 is shown herein as a oross having a .' central, intersectional area 162 formed at the intersection of grooves 164 and 166. The area 160 is shown in cross-section in FIG. 10 wherein it may be further seen that a differential fluid pressure applied across the diaphragm will induce the in-terseciional area 162 to first initiate rupture due to its relative structural weakness in tension. The rupture will then pro .
¦pagate along the grooves 164 and 166, radiating outwardly to isolat~ , ¦Itriangular sections 168 therebetween.
!I Referring now to FIG. 11, there is shown a perspective view of a ruptured ductile diaphragm 110 with sections 168 deformed ~¦downwardly, as against the side walls of the chamber 111. It l! may be seen that this ruptured configuration is the result of ¦ia fluid flow therethrough, either gas or liquid, which fluid ¦Iflow is essentially unrestricted subsequent to said rupture.
!ISince the diaphragm 110 ruptures in tension along the aforesaid Illines 164 and 166, no fragments of the rupture diaphragm 110 ¦lare left in the tool 10 to interfere with fluid flow. This llaspect is critical to maximum efficiency and safety of the tool ¦!10 and is herein referred to as a substan~ially complete, un-¦I fragm~nted rupture.
ll An advantage of cutting tool 10, when incorporating ¦¦diaphragm 110, and not known in the prior art, is the generally substantial lower ranges of gas pressure generated by propellen~ ¦
l50 to properly operate cutting tool 10. Such lower pressures ¦¦of course increase the safe handling of the tool in or out of the ! wellbore. Also, as outlined below, such lower pressures are considered to enhance the cutting action of the reaction product 1f the incendiary fluid 111.
il Il The diaphr~cJm 110, wherl constructed .~s described with reference to FIr~S. 9 an~ 10, can be provided to rupture within a close pressure range, 100 psi fGr e~ample, from about 500 to ¦ ~,000 psi differen-kial prcssure (and ahove though such higher I pressures ~ould never be needed in the tool of the present ¦l inven-tion). The present cutti.ng tool 10, whi~h may be buil-t in j various sizes, is presentlY used in most instanres with the rupture disc 110 havinq a rupture pressure in the ran~e of about ¦; 1,000 to 2,500 Psi differential pressure, thouqh the PreSSUres I ma~ qo hi~her or lower at times depending on different fac-tors.
¦ Referriny now to FIGS. 1-5, the complete interior of cutting tool 10 is at a-tmospheric pressure until the tool 10 is lowered to the selected position in well conduit 155 and the l propellant 50 ignited. There is generally a small air space ¦I below the top of upper diaphragm 110 and -the incendiary liquid ¦i 111. The cavity 122 also contains some air. As an illustrative description, when the propellant 50 is ignited it continues to burn and produce gas until expended. The amount of propellant I' is provided in sufficient quantity -to eventually reach a pressure ll sufficiently higher than the pressure inside tubing 155 to ¦l produce a good jetting action of the chemical reaction product through ports 130 properly against the walls of tubing 155, though the action of the chemical reaction product is the action that cuts the tubing without relying on the force of the fluid ¦ jet against the tubing wall.
Assuming that both the diaphragms llO are provided to ¦ rupture at 1,500 psi ~ifferential pressure, the gas pressure ¦ generated by propellant 50 ruptures first the top diaphragm then i! the lower diaphraym 110 in very close succession, forcing the 1170l63 incendiary chemical 111 into chamber 122 with the reac-tion product such as the steel wool giveIl as arl example. The reac-tion may produce addi-tional gas pressure, depending on the reactive com-ponents provided.
The support washer 139 may be provided of thickness to permit pis-ton 126 to clear ports 130 :immediately or o greater thickness to provide time for creating more or less pressure and reaction product before deforming or sheari.ncJ to allow the reaction product -to be jetted by the gas p.ressure through ports 10' . 130 against the ~alls of tubing 155. When the ports 130 are cleared Eor passa~e of the reaction product, 1:he pressure of the ¦compressible gas within tool 10 should -then be adequately greater than the pressure within tubing 155 to immedia-tely permit -the good jetting action previously described. Though the real ! 5 I pressure within the tool 10 may become quite high during the getting of all the reaction produc-t, the differen-tial pressure between the interior and e~terior of tool 10 need not be greater than necessary to produce the good je-tting ac-tion as previously described. Thus, if the tool were inadvertantly activated at the earth's surface or in a dry hole,.the di-Eferential pressure pr~c~,; C~t:~C~
utilized for the jetting~would remain relatively low and more ¦safe and consis-tent.
DESCRIPTION OF OPERATION
The apparatus of the present invention is operated -in the following manner: The various modules of the tool 10 are charged with the above-described propellant, ignition, aIld i.ncendiary chemical and ~ssem led as lllustrated .iD FIGS. l throuyh S. The Il I`
1~ -22-~1 .
Il ~
~ `` ~7t~:163 tool 10 is then connected to a suspension cable and lowere(l into the -tubing 155 to the point at which the cut is to be made. The tool 10 is next firmly anchored to the tubiny wall by -the con-trolled ignition of the propellant assembly 12. The propellant assembly is activated by the detonation of the Eiring sub 24 and fuse 32 through electrical communication Erom the surface of the borehole. The electric current may be provided from any suitable and conventional source (not shown). The igni-tion of the fuse 32 then ignites the propellant whereby yas pressure is created. The gas egresses downwardly into -the slip assembly 1~ and into the slip assembly housing 62. The slip housing 62 moves downwardly along the slip shaft 56 pushing the slips 86 against the ~andrel 92 causing the slips to deploy outwarclly into I the adjacent tubing 155. The tool ].0 is now securely anchored ¦ in a centralized configuration withln the borehole.
The propellant gas within the now anchored tool 10 l continues to build up from tile gases produced by the propellant I sub 12 until the upper dia2hragm 110 atop the chemical module 111 ~j is ruptured. The rupture of -the upper diaphragm 110 causes the 1 incendiary fluid contained therein to mo~e downwardly under ~¦ pressure rupturing the lower diaphragm 110 and egressing into ¦¦ the ignitor sub 120. In the ignitor sub 120 the incendiary fluid ¦l engages the ignitor hair such as s-teel wool there~elow.
¦¦ The incendiary fluid is activated in the ignitor hair, with a 1¦ resulting build-up in gas pressure which will be exerted against the end of the piston 126, forcing it downwardly into the cylin-der portion 136 to uncover the inner ends of the discharge ports ~7V~3 130. The pre-iynited incendiary Eluld will thus discharge rom -the discharcJ~ por-ts 130 at tremendous pressures and velocity as well as at high temperatures. The discharging fluid will then strike -the pipe wall or tubing 155 opposite the ends of ! the passages, whereln -the fluid will react with the pipe wall which will be burned or dissolved effecting the desired cutting result.
It may be seen that -the pressure oE the propellant gases l causing the slips 86 to deploy outwardly into the tubiny 155 ¦ has securely lodged the tool 10 within the wellbore. It may also be seen that the tool 10 will remain lodged within the wellbore unless the slips 86 are suitably retracted. For this reason, when the propellant gas pressure is substantially ¦ vented the biasing force of the spring 60 returns the slip ¦ housing to its upright position whereby the slips 86 are separated from around the mandrel 90. In the retracted position ~he slips 86 are automatically retracted from the side walls of the tubing 155 under the tension of the garter spring 1 96 disposed therearound. Once the slips 86 assume their I retracted position the tool 10 may be removed from the borehole ¦ by pulling it upwardly. Likewise it may be recharged for subsequent usage.
i In the alternative struc-tural embodiment of the tool 10 l shown in FIGS. 12 and 13, it may be seen that the identical ¦¦ procedural steps are required to activate the tool 10 to effec-t cutting in the borehole. However, the specific operation of the slip assembly 1~ is effected by an upward driving of the slips against the rnandrel 92 i.n that the slip assembl~ module 1~ has been inverted. In all other respects, th~. operation of the tool 10 is the same as described above, with the exception that during removal should slip retraction become a problem, an upward tugging on the supporting cable wil]. permit the mandrel 92 -to be pulled from beneath the base of the slips 86 to permit said slips to return to their initial position. In like manner, the garter spring 96 then serves as a biasinc3 I element for returning the slips 86 to their initial position.
10 Should the slips ~6 yet ~ail to retract for any reason, the tool 10 maY still be removed from the borehole as set forth above. More particularlv, the chamfer 170 of the slip structure sho~n in FIG~ 12 Permi.ts the slip to be "draqcled" upwardly in a "sled" fashion This desiqn aspect may thus be seen to add another utili-ty dimension to the particular confiquration of the cvlindrically seqmented S].iP arraY set for-th in the present invention-¦ It is therefore believed that the operation and construc l¦tion of the above-described invention will be apparent from Ithe foreqoinq description. While the method and apparatus for ¦chemical cuttinq in a borehole shown and described has been characterized as beinq preferred, it will be obvious that ;Ivarious chanqes and modifications may be made without departinq Ifrom the spirit and the scope of the invention as defined in the f~llowincl claims.
1.
Il .,
t~ t fi ~
BACKGP~OI~D OF THE INVENTION
This invention relates to a method of and apparatus for cutting tubing, and, more particularly, to a system employing a chemical cutting fluid of highly reactive incendiary character such that when brought into contact with tubing suspended in a wellbore, it will quickly burn therethrough. The term "cutting" is used herein as a generic term to include cutting, severing, perforating or slotting of tubing and other objects, as well as their complete disintegration. The objects referred to may be metal pipe or wellbore lining, including the earth formation surrounding or forming the wall of the wellbore or extraneous foreign objects such as lost drilling tools suspended therein. Prior apparatus for cutting tubing are commonly referred to simply as "tubing cutters". Such cutters are used, for example, in drilling operations wherP it is desired to detach a bullplug or other obstruction from the lower end of a tubing in a wellbore by severing the tubing above the bullplug.
Tubing cutters are also used to salvage the tubing from an abandoned well or the part of the tubing above a stuck point.
There are various types of prior art tubing cutters, for example, shaped charged cutters and chemical cutters. There are problems associated with shaped charge cutters, however, because a tubing string into which the cutter can be lowered into the wellbore, oEten contains a pump seating nipple or landing nipple which foxms a partial constriction in the tubing by reducing the size of the bore. This landing nipple may be located at a point intermediate the surface and the part of the tubing to be cut. In tubing cutters which are constructed I `~ 0 ~ ~ 3 to'b~ part,ially recovered, tlle force ~c,~n~rated b~ an ~xplosion of a shapecl charge in the tubin~ cutter causes parts of the cutter which are not disintegrated to becorne expanded or the end of the tubing to become flared. This expansion oEten times prevents the retxieval of the expanded part.
Chemical cutters have been shown to be very reliable whi le overcoming many of the aforesaid problems. They have been referred to as the simplest and most efficient tool for tubing cutting because the cut is made without flare, debris or 10, damage to the adjacent string of tubing. One such prior art construction is shown and described in U. S. Pats. 2,918,]25, ¦ issued Decernber 22, 1959 and 3,07G,507, issued Februar~ 5, 1 1963, both to William G. Sweetma~ s set forth in the ¦ Sweetman Patents, the cutting fluids employed in accordance ,I with that invention are fluids which are extremely active chem-ically and which when brought into contact with most oxi-dizable substances, react violently therewith generating ex-tremely high temperatures sufficient to melt, cut or burn -the adjacent tubing. Fluids such as halocJenflourides, ineluding cholorine tri-flouride as well as bromine tri-flouride, have j been proven to be effeetive in tubing cutting.
There are several considerations which remain of major ¦l import in the utilization of such chemical cutters as set forth Ij above. First, the secure anchoring, or downhole positioning j of the cutter within the wellbore i5 a major consideration. The cutter must be fixedly positioned within the wellbore so as i to make a uniform cut and to prevent the flaring or creation ;
I I ~O~ G3 of deb.ris within the wellhore to :Erustrate the attempt of an effective cutting operation. ~he ricJidity of the anchoring and centralized positioning is thus oE critical import. It is ¦ also necessary that the overall unit be functionally reliable, ¦ including sure igni-tion, positive fluid seals and cnvironmental ~¦ durability. ~or example, the insertion of the -tool into -the ¦~ wellbore is coincident with immersion in those ~luids normally present therein such as mud and sand. It is -thus important that ¦
~¦ sueh substances do not adversely affect -the operation oE the subject -tooling.
It would be an advantage therefore to provide a chemical tubing eutter which would overcome many of the problems of the . prior art wherein the tubing cutter could be reliab].y and ¦ securely positioned within the wellbore for the cut-ting oper-11 ation. It woul~l be a further advantage to provide a single ¦I tubing cutter seeurable within known conduits of a differen-t jl size while effecting the equivalent reliability. The method and 1~ apparatus of the present invention includes such a chemical j¦ tubing cutter wherein a multi-àngulated slip assembly is utilized 20 1I for circumferential engagement within tubirlg of different sizes.
The tubing cutter of the present invention also provides a means for the reliable sealing, ignition and actuation of the in- j cendiary elements therein for the proper maintenance and control ~l, thereof.
1! SUMMARY OF THE INVENTION
! The invention relates to a chemical cuttinc~ method and ¦ apparatus including a tubular array containing means for I
;
IJ~(~16~3 central.ly securinCJ ltse,lf in a borchole ancl CUttinCJ the tubing therearound wi.th an incendiary chem:ical fluid. r~ore par-ticularly, one aspec-t of the invention includes the incendiary chemical fluid of a halocJen flouride dlsposed within a chemical module intermediate of a propellant and slip assembly module l array and a discharge head assembly. The chemical is caused to ¦¦ be discharged in one or more high veloci.-ty streams, or ~,ets, by applying to the body ol the fluid a suitab]e compressible ¦ pressurizing medium of adequate magnitude. The pressurizincJ
:1.0 I medium is a gas generated by the igni-tion ancl regular burning ¦ of one of various types of relatively slow burni.ng propellants.
¦¦ By uti].izing an electrical composition resistor as an ignition ¦ element, the iynition of the propellant may be more effectively Il and safely controlled to generate the gas at a predetermi.ned ¦I time suitable for the particular application and the desired I pressurizing force confined within the body oE the cutting ~ ,U~.t~
fluid. Furthermore, a ~r~c~ible.,..rupturable~diaphragm is utilizec .
to store said fluid wherein the diaphragrn is selectively formed I to rupture within a narrow range of di.fferential fluid pressure ','0 1l to obtain buildup of the desired pressurizing force before the ¦¦ cutting fluid is activiated.
In another aspect of the invention, the slip assembly j i.s provided in a cylindrically segmented array comprising a plurality of arcuate, tubing engaging elements assembled cir- ¦
~5 I cumferentially about -the sli.p assembly modu].e substan-tially , therearound. The array is adapted for the outward deployment thereof for engaging the maximum surface area of the tubing thereabout in predefined secured engagement patterns. ~ach slip li .
`` 1~7~3 .~ elemen-t includes an elongated section of arcuate cross-sectional confi~urati.on having laterally e~tenclin~,~-tu~inq engagement edyes constructed thereacross in generally parallel sp~ce rela-tionship, longitudinally therealong. X'he la-teral eclyes, or teetil of each I slip are furthermore constructecl iSl -two discxete, longi,-tudinal ¦ angulation configurations complimentally designed to engage two I distinct diameters of tubing acljacent thereto, uniformly -there-¦¦ along, and centrally therein.
Ii In yet another aspect, the s],ips are constructed and ¦ll assembled whereby the longltudinal edc;es thereof in the undeployed ¦¦ mode generally cireumferentially encompass -the entire circum-¦ ferenee of the underlying slip assembly region adjacent thereto ¦ for providing maximum utilization of surface area of the slip ¦¦ assembly for engaging -the adjaeent tubi.ng therearound. In ll this manner, maximum strength and anchoring may be effected ! within the wellbore.
BRIEF DE CRIPTION OF TE~E DRAWINGS
ll For a more complete understancling of the present inven-¦l tion and for further objects and advantages thereof, referenee ¦¦ may now be had to the following descripti.on taken in conjunc- ¦
tion with t,he accompanying drawings, in which:
ii FIGS. 1 through 5, together, comprise a longitudinal, eross-seetional, side-elevational view of one embodiment of a Il ehemical cutting apparatus eonstrueted in aeeordanee with the ?.5 1I prineiples of the present invention, illustrating an array of propellant, ehemical, slip and discharge head modules in end-to-end relation;
FIG. 6 is a top plan, cross-sectional view of the inter-mediate portion of the tubing cut-ter assembly of FIGo 3 taken along lines 6-6 thereof and lllustratina tbe cylindrically 11 .
1 '~
segmentecl grippirlg slips assembled -therearollnd;
F[~. 7 is an enlarged, side-el.eva-tional view of an in-, dividual slip from the s].ip array of FIG. 3, illustrati.ng -the ¦ gripping tee-~h formed with two discrete angulation pat-terns;
1. FIG. 8.is a fragmentary side-elevational, cross-sec-tional view of a slip assembly in an outwardly deployed configu-ration engacJing -the side wall of tubin~ in a borehole;
FIG. 9 is an enlargecl top plan view of a rupture dia-¦¦ phragm of the chemical module of FI~
l FIG. 10 is a side-elevational, cross-sectional view of ¦ the rupture diaphragm of FIG. 9, takerl along li.nes 10-10 ¦I thereof;
FIG. 11 is an enlarged perspective view of a rupture !i diaphragm illustrating the ruptured configuration thereof for ¦¦ providing a substantially full Elow opening; and ¦I FIGS. 12 and 13 comprise a longitudinal, cross-secti.onal side-elevational view o:E an alternative embodiment of the slip assembly module of the present inventi.on.
DETAILED ~ESCRIPTION
¦ Referring first to E`IGS. 1 -through S, there is shown a cutting tool designated generally by the number 10, which is l inserted in a strin~ of tubing (not ShOWII) extending into a ¦ wellbore which may be lined with a metal casing (not shown).
I The cutting tool cornprises in downwardly arranged succession, a ¦ propellant module assembly 12, a slip a.ssembly 14, a chemical ¦I module assembly 16, and a discharge heacl assembly 18. These ~¦ several modules, which are constructed of suitably strong mater.ial such as steel, are generally cylindrical and connected 1~70163 ¦ together i.n end-to-end coaxial rela-tion. The modular array ¦ forms an elongated cylindrical tool 10 o~ substantially uniform ¦ exterior diameter, which is adapted for insertion into -the I tubing string on the end of a fl,exible cable, or the like (not S ~ shown). A head assembly 2n, is connected to the upper end of I the cutting tool 10 and includes a socket 22 of generall~ con-¦¦ ventional form which connects the upper end'of the tool 10 to the tool string or cable which is employed for l.owerincJ and . j raising said tool in the wellbore. The aforesaid tool stri,ng :lO , or cable, al-though not shown, includcs means for transmitting ¦ an electric current from a conventional source about the well-l bore to the tool 10 for the operation thereof.
Referring particularly now to FIG. ]. there is shown the propellant module assembly 12 disposed beneath and secured to 1.5 the head assembly 20. In-terconnecting the head ~ssembly 20 I and the propellant assembly 12 is a firing sub 24 containing an ¦ electrode 26 centrally therethrough insulated within a dielectric ! sleeve 28 therearound. A mating interconnection element, or ¦¦ plug 30 is construc-ted atop the electrode 26 for electrical ~0 ¦¦ communication with the surface above the borehole. Immediately ~l, beneath the elcctrode 26 and the firing suh 24, ~here depends ¦l a fuse assembly 32 including a}l exp].osive initiator element Il 34 of generally conventional design. The fuse assembly 32 being ¦
¦¦ placed in electri.cal contact wi-th the end of the electrode 26 ,,¦ provides means for igniting a controlled burning propellant disposed therebelow. ~ longitudinal passage 36 provides com-~¦ munication between the initiator cap 34 and a propellant chamber ¦ 37 formed in the propellant module assemb].y 12. The modu1e I~ -8-I J ~O l6 ':~
I
I
12 includes an outer sleeve 3~ couplecl to the fuse assembly v:ia a threaded coupliny 40. It should be noted that the various modules and suhassemblies describeti here~in, are conventionally coupled one to the o-ther by -threaded couplincJs and sealed with O-rings positioned therewithin. The -threaded couplings and O-rings are no-t numbered but are clearly illustrated as is con~
ventional in the art. The passage 36 terminates into a central bore 44 forming the chamber 37 and con-taining a propellant housing, or spacer 46 having a plurality of ports 48 formed along the length thereof. The propellan-t spacer 46 contains a pluralit~
of power pellets 50 stacked therein or an integral propellant grain (not shown) and adapted for being ignited by the fuse assembly 32 disposed thereabove for the generation of a pro-pellant gas.
¦ Referring now to FIG. 2, there is shown the lower part of the propellant assembly 12 and particularly the lower region of the power charge sleeve 46 containing the propellant therein.
sui-table annular region may be provided around the propellant spacer 46 and within the tubular bore 44 of tht-~ propellant chamber 37 as shown for the generation of suitable pressuri~ing gases therein. The gases generated in -the propellant assembly 12 are allowed to escape downwardly into -the lower slip assembly 14 for actua-tion thereof via a tubular bore 52 constructed beneath the propellant chamber 37 in an upper region of the slip il assembly 14 comprising an upper slip sub 54. The slip sub 54 is threadably coupled to a central slip shaft 56 depending therefrom. The slip shaft 56 comprises the~ structural center of the slip assembly 1~ and includes a central bore 58 formed Il ~1 _9_ ~1 .
1170~63 thercthrough in a~uttlng oommunication wlth the slip sub I passage 52 for permit-ting the propellant gases to esca~e there-¦ through.
¦ Referring now -to the lower region of the tool 10 ¦ illustrated in FIG. 2, there is shown a cylindric,al housing 62 with the slip shaft 56 received therein. A longitudinal compression spring 60 is provided within the slip assembly housing 62 within a central space 6~ formed tllerein. 'i`he spring . 60 circumferentially encompasses the slip shaEt 56 longitudinally 1¦ therealong longitudinally biasing the sli.p housing 62 upwardly ! against the upper slip sub 5~.
Referring now to FIG. 3, there i.s shown in the upper region thereof, the lower section of the slip assembly module j 14 of the cutting tool 10. The slip shaft 58 rnay be seen to ¦ include a lower seating flange 66 for receiving the base o~ the spring 60 thereagainst. The flange 66 inclues a circumferen-j tial slotted portion 68 containing an O-ring 70 therci.n for j purposes of sealing the slip shaft 56 rela-tive to -the slip ¦¦ housing 62. A piston-cylinder configuration is thus constructed I between the slip shaft 56 and slip assembly housing 62 respec-¦ tively. ~eneath the flange or piston 66 the central passage 58, extending through the slip shaft 56, is vented through venting ports 72 extending transversely therefrom and in communication with the passage 58 for venting a lower, annular space 7~ beneath the flange 66. The slip housing 62 is constructed w~th a lower . ¦ flange bulkhead 76 containing an O-ring 78 therewi-thin and around the slip hafC 56 Eor seeling the said housing ther~against.
ll 1 :~7~63 I In this manner, propellant gases escapincJ through the passage 58 will he vented into the annular space 74 for ~reating a pressure agains-t the seating flange 66 and causincJ -the slip ~ assembly housing 62 to be driven downwardly alon~J the slip ¦ shaft 56, a~ainst the biasing compression of the spring 60.
Referriny now to the lower region of FIG. 3, there is l shown the lower portion of the slip assembly housing 62 con-structed with a partially open-ended annulus 80 constructed j therein. A lower con-trally aperture flange 82 forms the base 1ll portion of th~ annulus 80 and receives the upper head section 84 of an array 85 of gripping slips 86 pivo-tally seated therein about the slip shaft 56. The gripping slips 86 are constructed ¦I with a plurality of gripping teeth 88 on the outer surface ¦I thereof. The teeth 88 are adapted to engage and secure]y grip 1- 1¦ the wall of adjacent tubing as will be described in more detail below.
ll A plurality of slips are provided around the slip-¦l shaft 56, each being constructed with a lower, internally ¦¦ tapered end 90. The end 90 of each 51i.p 86 is adapted for ¦1 abutting a complementally tapered frusto-conical mandrell 92 ¦l of a lower slip sub 94. The mandrel 92 functions as an incline ¦ plane for the slips 86 as -they are driven downwardly with the I slip assembly housing 62 in response -to the generation of ¦I propellant gases within the propellant module 12. The downward ,¦ movement of the slips 86 over the mandrel 92 causes the outward, 'I angular dep]oyment of the slips 86 for anchorin~ against the adjacent tubing. The slipshaft 56 may be seen to be struc-turally interconnscted with ~ lower slip sub 4 through a ~ -~ 5 3 threaded lnterco~ ection therebetween. Sprillg means 96 such as "garter springs" are provided around the slips ~6 through a slotted por-tion 100 forrned above the teeth 88. The sl?ring means 96 may include any suitable elas-tic material or spring ¦ construction sufficient to lightly bias the slips 86 in the closed position shown.
Referring now to FIG. ~, there is shown the lowermost portion of the slip assernbly module :l4 wherein the passage 58 ll of the slipshaft 56 cornrnunicates with a central bore 102 formed ! within the lower slip sub 9~. The bore 102 comprises a passage l¦ for the egress of propellant gases from the passage 58 into the ¦1 lower chemical module 16. The chemica:L module 16 is connected ¦¦ to the slip assembly rnodule through a scaled interconnection jl 104, wherein means are constructed for sealably containing the 1, select incendiary fluid stored in said chemical module.
¦ll gasket 106 is thus provided beneath the passage 102 atop a !i diaphragm retainer 108 abutting a rupture diaphragm 110. The ¦ diaphragm 110 is constructed with an area of reduced cross-j section for rupturing at a predefined fluid pressure dif~eren-~0 , tial thereacross in a manner ~o comp:Letely open the flow passage therethrough as will be described in more detail below. The diaphragm 110 seals a fluid chamber 112 centra]ly bored within the chemical module 16 therein con-taining a selected incendiary ! fluid 111. The term incencliary chernical is used herein as I referring to a higllly reactive chemical which is particularly ¦ adapted for such downhole cutting operation. In particular, bromine tri-flouride has been found to be acceptable as an . 1~70~
¦ incendiary fluid for cuttiny operat:i.ons i.n accordance with the I teachings o~ the present lnvention. The aEoresaid incend.iary ¦ fluid is fur-ther contained within the chamber 112 by a lower ¦ rupture diaphragm 110. Likewise, a cliaphragm retainer 116 and j gasket 118 are provided therebeneath Eor the securement and sealin~ of the diaphragm 110 thereabove.
Compressed propellant gas generated in -the propellant ¦ module 12 acts in a select manner and at a select pressure to ¦ cause the rupturing of the rupture diaphragm 110, forcing the :L0 ! incendiary fluid 111 within chamber 112 downwardly, rupturing ¦ the lower rupture disc 110 for passage in-to an igniter sub 120 partially housing within the chemical module assembly 16.
The ignitor sub 120 is threadably coupled -to -the chemical I module 16 and is construated with a central chamber 122 con-lS 1¦ taining steel wool 123 which ma~ be coated with oil, or a Il similar product suitable for reaction wi.th the respective in-cendiary fluid utilized. The steel woo]. 123 promotes a violent reaction when it contacts the downwardly egressing incendiary ¦ fluid 111 for the generation of further pressure and activity.
¦l A lower longitudi.nal passage 124 is constructed benea-th the ¦I chamber 122 in communication therewith :Eor the escape of the activa-ted incendiar~ fluid 111.
ll Referring now to FIG. 5, there is shown the lower por-¦l tion of the igniter sub 120 and the passage 124 ex-tending there-1I through and communicating with a discharge head piston 126 i positioned within the discharge head module 1~. The piston ' 126 is slidably mounted within an axial bore 126 constructed !
il within the discharge head housing 129, which is .~ormecl with a I plurality oE radially extending ventin~ ports or jets 130 extending outwardly o the central bore 128. The piston ].26 is l mounted within the bore 12~ for downward movement ar-d ~s suitably sealed therein with a plurality of smaller O-rinys 132 secured therearound both above and belo~J the discharge ports 130.
Proper sealing of the piston is necessary to ensuxe the noncon-¦ tamination of the tool 10 from well flui.ds during insertion I within a wellbore.
! The discharge head module 18 includes a lower bullnose 134 depending from and threadably coupl~d to the housing 129.
The bullnose 134 forms the lower encl of the tool 10. The bull~
nose is comprised oE a ~enerally cylindrical section having I axial bore 136 constructed for receiving the piston 126 once ¦ said piston is driven downwardly by the pressure oE the pro-pellant and fluid generated thereabove.
The bullnosel34 is coupled to the discharc3e head housing jj 129 with a support washer 138 lodged therebetween. The suppor~
¦¦ washer 13~ is constructed with a central aperture 1~0 having - 20 11 a diameter small enough to retain the piston 126 thereabove.
~¦ The washer 138 is also constructed oE sufficiently thin material to deform and/or shear under preselected forces to permit Il the downward movement of the pistOIl 126 under pressure of the ¦ escaping incendiary fluid 111. The downward movement of the ¦. piston 126 into the chamber 136 of the bullnose 13~ opens the chamber 128 to the discharge ports 130, permi-t-ting the incen-diary fluid 111 to jet therethrough. The discharge ports 130 are constructcd in a radially extending pat-tern (not shown), - il . I
1 17t~163 which pattern is of convenl:iona]. "overlap" design. Arl "overlap"
pattern is one wherein flui-l spray of adjacent discharge ports is contiguous upon -the surface being cut so tha-t the incen-diary fluid discharged from said adjacent ports forms a sub-S ¦Istantially con-tinuous cut pattern.
Referring now to FIG. 6, there is shown a top plan vie~
of the slip assembly 14 of FIC7. 3 taken along lines 6-6 thereoF
and more clearly illustrating the positi.oning of the slips 86 . ¦thexealong. In the tool 10 of the present embodiment, six slips 186 are provided to comprise a generally cylindrical array, segmented one from the other and constructed for outward deploy-ment from the slip shaft 56. The terrn "cylindrically segmen-ted"
is hereinaft~r utilizeA in referring to the particular slip llassembly array 85 of the present invention. The cylindrically Ij segmented slip assembly 85 is constructed whereby inner surface area of the slips 86 substantially encompasses the slip shaft 56 therebeneath in a generally cylindrical, segmented housin~
¦confic3uration. It should be noted that the assembly of the slips 86 into the array 85 requires a "keyed" subassembly into the lannulus 80 (FIG. 3). With the shaft 56 removed, the slips 86 ¦are inserted into the annulus 80 and keyed together. The shaft 58 is then inserted to effec-t an assembly wherein the slips 86 are locked into place, one against the other. The outward l deployment of the slips 86, wi-th the head sections 84 pivotiny ¦¦ within the annulus 90, then permits engagement of the adjacent ¦ tubing with maximum gripping effectiveness for secure anchoring thereagainst. Additionally, the segmente~, cylindrical con-~figuration of the slips array 86 ensures the centralization of I
il -15-~1 1170~3 the tubing cutter 10 w:ithin the wellhore since each slip deploys in a direction opposite to that of an opposing slip, an equivalent distance, automatically centralizing the position of the tool l 10. Certain prior art constructions have heretofore utilized gripping slips having grippin~ teeth inscribed upon the outer Isurface thereof; however, such slips have no-t been provided i.n ¦the segmented cyli.ndrical array provided herein and in -the ¦gripping teeth angulation pat-terns facilitatin~ multidiameter . applications as discussed below.
¦ ReEerring now to FIG. 7, there is shown a longitudinal, l cross-sectional elevation of a slip 86 wherein the gripping j¦teeth 88 formed upon the outer surface thereoE may be seen in j'more detail. It should be noted that the gripping teeth 88 I! of the particular embodiment shown herein are provided in two 1I discrete angulation patterns. These patterns are illustrated : Iby the phantom lines 150 and 152 drawn on the surface of the gripping slip 86. ~he phantom line 150 illustrates a first angulation pattern for gripping ~eeth 88 formed on the upper half of the slip 86. The particul.ar construction anyle of the ~ 20 Iteeth 88 below line 150 is adapted for uniformly engaging an : ladjacent tubing wall of a certain diameter upon deployment of the ~ Isubject slips. Each slip 86 engages the adjacent tubiny with :~ 'equivalent surface area engagement and pressure, due to the Icentralizing effect of the segmented cylindrical array 85 of the jslip assembly 1~. The angulation pattern defined by the phantom line lS0 may be designed for a particular deployment an~le ¦lequivalent to a particular tubing diameter.
Il .
Il . I
`I .
._ I
~ l I l 7~3 Stil.1 referring to FIG. 7, phantom ~ e 152 illustrates ¦ a second grippi.ng teeth angulat:ion pattern of less acute I construction relative to the centrcll .lXiS o the sl.ip shaft 56.
¦ In this manner, the slip 86 may be deployed at a grea-ter angJ.e ¦ than provided for by said first angulati.on pattern -to uniformly ¦ engage a tubing wall of larger diameter.
Referrlllg now to FIG. 8, there is ShOWIl an example of the aforesaid flrs-t and second anc;ulation patterns irl engagement with a tubing wall and illustra-ted in exaggerated form. The upper gripping teeth 88 beneath the phantom line 150 are shown to be left unengaging the adjacent tubing 155 since the slip 86 shown thereln is deployed at the select angle for anchorirlg tubing of a second larger diameter. It may be seen that if the l tubing 155 were of a smaller select diameter, the upper section 1 of the gripping teeth 88 would engage said tubing with the lower teeth, beneath phantom line 152 left unengaged. In -this rnanner, I a single cutting -tool 10 may be utili~ed in boreholes of more ¦ than one diameter for cutting operations therein.
j! ReEerring now to FIGS. 12 and 13 there is shown a ¦, slightly different embodimen-t of slip assembly 1~. As readily ¦~ noted, in these drawings, slip assembly 1~ is virtually the ¦I same construction as shown in FIGS. 2 and 3 except it is mounted in an inverted relationship top to bo-ttom in the cutting -tool I 10. It may also be seen that the profile of slip 86 and in ¦ particular -the gripping teeth 88 is slightly modified relative ! to the proEile shown in l;~IG. 3. ~ccordingly, li]ce elements ¦ oE the slip assembly 1~ as shown in EIIGS. 2, 3, 7 and 8 bear the same numbers as the elements shown in FIGS. 12 and 13.
I' .
Il , .
i~ 117~)~63 ¦ The operatlon of the sLip assembly 14 as shown in FIGS.
¦ 2 and 3 is as follows: The gas pressure i.n space 72 causes the slips to engage the well tubing 155 in which tool 10 is positione~
and therein holdin~ the tool 10 immobi:le until all the liquid reactive chemical is ejected through the ventiny ports, or jets, 130 and until the gas pressure is dissipated by egressillg behi.nd said liquid through said venting ports. As previously descri,bed, after the gas pressure has dissipated, the sprin~ 60 is provided to retract the s.lip assembly 85 away from the walls o t~le tubing L0 ¦ 155 into its ini-tial retracted position. However, for some reason should spring 60 not allow the slip assembly 85 to de-tract, it would be difficult to disengage the slip 86 from the tubing 155. The only possible mechanical mani~ulation in suc:h a position would be through the cable .Erom which cutting tool 10 is suspended. The only Eeasible manner oE disengacJement in this instanc~ is to impart a downward jarring for the tool. I
10. Wireline jars are available for this purpo.se but are expen~ ¦
sive and a nuisance to use. It may thus be seen tha-t in the embodiment of FIGS. 12 and 13, if spring 60 fails to disengage ¦ slip assembly 85, a tension applied by upward pull on the wire-¦l '.ine will draw the conical mandrel 92 out :Erom under the slips ~! 86 quite readily for fa_ilitating removal of the cutting tool 10 from tubing 155.
I¦ At times, the slip retaining means 100 may be damaged 1¦ or destroyed by flow of the incendiary fluid past assembly 14.
¦l In the situation of FIGS. 2 and 3, such happening is of little I consequence since the slips 86 tend to pivot inwardly when il Il -18-I ~ 70163 cutting tool 10 is pulled upwardly. However, the reverse is ¦1 evident in the situation of FIGS. 1.2 and 13. ':['o alleviate hang-up problems in the tubing, slip ~6 o.E this particular ernbodiment l is provided with a bevel or chamfer 170 as shown. Bevel. 170 allows each slip a6 -to slide along the tubing wall in "sled"
fashion if slip retaining means 100 becomes inoperable alld fails to retract the slip. The grippinc3 teeth 88 are also shown with a slight variation in -the l~rofile thereof. As shown in FI~
7, the gripping tee-th 88 are of a "buttress" proEile slanting ~0 ~ upwardly. In this alternate embodiment the teeth 88 are of e~ual sided of "V" shape with -the included angle of the apex of -the "V" being about 50-90~. This slip tooth profile is considered superior in some respects in that it may be dis-1l engaged from embedment in the tubing more easily and also because i5 ¦¦ it also remains firmly engaged by thepiston 66 un-til the pro-¦~ pellant gas pressure is dissipated through the jets 130 following evacuation of the incendiary chemical fluid. This slip also ¦ is of dual construction angle as shown by lines 150 and 152 of l FIG. 7 shown in FIG. 8.
` ~eferring now to FIG. 9, there is shown a top plan view of the rupture diaphragm 110. The diaphragm 110 includes an area of reduced cross-section 160 constructed by stamping, Il cutt~ng or similar fabrication technique. The area 160 effec-¦l tively ensures the rupture of the di.aphragm at a closely pre--1I selected differential fluid pressure which is an impor-tant ¦I safety and reliability parameter. The pattern of the area of reduced ~ross-sec~ion 160 is shown herein as a oross having a .' central, intersectional area 162 formed at the intersection of grooves 164 and 166. The area 160 is shown in cross-section in FIG. 10 wherein it may be further seen that a differential fluid pressure applied across the diaphragm will induce the in-terseciional area 162 to first initiate rupture due to its relative structural weakness in tension. The rupture will then pro .
¦pagate along the grooves 164 and 166, radiating outwardly to isolat~ , ¦Itriangular sections 168 therebetween.
!I Referring now to FIG. 11, there is shown a perspective view of a ruptured ductile diaphragm 110 with sections 168 deformed ~¦downwardly, as against the side walls of the chamber 111. It l! may be seen that this ruptured configuration is the result of ¦ia fluid flow therethrough, either gas or liquid, which fluid ¦Iflow is essentially unrestricted subsequent to said rupture.
!ISince the diaphragm 110 ruptures in tension along the aforesaid Illines 164 and 166, no fragments of the rupture diaphragm 110 ¦lare left in the tool 10 to interfere with fluid flow. This llaspect is critical to maximum efficiency and safety of the tool ¦!10 and is herein referred to as a substan~ially complete, un-¦I fragm~nted rupture.
ll An advantage of cutting tool 10, when incorporating ¦¦diaphragm 110, and not known in the prior art, is the generally substantial lower ranges of gas pressure generated by propellen~ ¦
l50 to properly operate cutting tool 10. Such lower pressures ¦¦of course increase the safe handling of the tool in or out of the ! wellbore. Also, as outlined below, such lower pressures are considered to enhance the cutting action of the reaction product 1f the incendiary fluid 111.
il Il The diaphr~cJm 110, wherl constructed .~s described with reference to FIr~S. 9 an~ 10, can be provided to rupture within a close pressure range, 100 psi fGr e~ample, from about 500 to ¦ ~,000 psi differen-kial prcssure (and ahove though such higher I pressures ~ould never be needed in the tool of the present ¦l inven-tion). The present cutti.ng tool 10, whi~h may be buil-t in j various sizes, is presentlY used in most instanres with the rupture disc 110 havinq a rupture pressure in the ran~e of about ¦; 1,000 to 2,500 Psi differential pressure, thouqh the PreSSUres I ma~ qo hi~her or lower at times depending on different fac-tors.
¦ Referriny now to FIGS. 1-5, the complete interior of cutting tool 10 is at a-tmospheric pressure until the tool 10 is lowered to the selected position in well conduit 155 and the l propellant 50 ignited. There is generally a small air space ¦I below the top of upper diaphragm 110 and -the incendiary liquid ¦i 111. The cavity 122 also contains some air. As an illustrative description, when the propellant 50 is ignited it continues to burn and produce gas until expended. The amount of propellant I' is provided in sufficient quantity -to eventually reach a pressure ll sufficiently higher than the pressure inside tubing 155 to ¦l produce a good jetting action of the chemical reaction product through ports 130 properly against the walls of tubing 155, though the action of the chemical reaction product is the action that cuts the tubing without relying on the force of the fluid ¦ jet against the tubing wall.
Assuming that both the diaphragms llO are provided to ¦ rupture at 1,500 psi ~ifferential pressure, the gas pressure ¦ generated by propellant 50 ruptures first the top diaphragm then i! the lower diaphraym 110 in very close succession, forcing the 1170l63 incendiary chemical 111 into chamber 122 with the reac-tion product such as the steel wool giveIl as arl example. The reac-tion may produce addi-tional gas pressure, depending on the reactive com-ponents provided.
The support washer 139 may be provided of thickness to permit pis-ton 126 to clear ports 130 :immediately or o greater thickness to provide time for creating more or less pressure and reaction product before deforming or sheari.ncJ to allow the reaction product -to be jetted by the gas p.ressure through ports 10' . 130 against the ~alls of tubing 155. When the ports 130 are cleared Eor passa~e of the reaction product, 1:he pressure of the ¦compressible gas within tool 10 should -then be adequately greater than the pressure within tubing 155 to immedia-tely permit -the good jetting action previously described. Though the real ! 5 I pressure within the tool 10 may become quite high during the getting of all the reaction produc-t, the differen-tial pressure between the interior and e~terior of tool 10 need not be greater than necessary to produce the good je-tting ac-tion as previously described. Thus, if the tool were inadvertantly activated at the earth's surface or in a dry hole,.the di-Eferential pressure pr~c~,; C~t:~C~
utilized for the jetting~would remain relatively low and more ¦safe and consis-tent.
DESCRIPTION OF OPERATION
The apparatus of the present invention is operated -in the following manner: The various modules of the tool 10 are charged with the above-described propellant, ignition, aIld i.ncendiary chemical and ~ssem led as lllustrated .iD FIGS. l throuyh S. The Il I`
1~ -22-~1 .
Il ~
~ `` ~7t~:163 tool 10 is then connected to a suspension cable and lowere(l into the -tubing 155 to the point at which the cut is to be made. The tool 10 is next firmly anchored to the tubiny wall by -the con-trolled ignition of the propellant assembly 12. The propellant assembly is activated by the detonation of the Eiring sub 24 and fuse 32 through electrical communication Erom the surface of the borehole. The electric current may be provided from any suitable and conventional source (not shown). The igni-tion of the fuse 32 then ignites the propellant whereby yas pressure is created. The gas egresses downwardly into -the slip assembly 1~ and into the slip assembly housing 62. The slip housing 62 moves downwardly along the slip shaft 56 pushing the slips 86 against the ~andrel 92 causing the slips to deploy outwarclly into I the adjacent tubing 155. The tool ].0 is now securely anchored ¦ in a centralized configuration withln the borehole.
The propellant gas within the now anchored tool 10 l continues to build up from tile gases produced by the propellant I sub 12 until the upper dia2hragm 110 atop the chemical module 111 ~j is ruptured. The rupture of -the upper diaphragm 110 causes the 1 incendiary fluid contained therein to mo~e downwardly under ~¦ pressure rupturing the lower diaphragm 110 and egressing into ¦¦ the ignitor sub 120. In the ignitor sub 120 the incendiary fluid ¦l engages the ignitor hair such as s-teel wool there~elow.
¦¦ The incendiary fluid is activated in the ignitor hair, with a 1¦ resulting build-up in gas pressure which will be exerted against the end of the piston 126, forcing it downwardly into the cylin-der portion 136 to uncover the inner ends of the discharge ports ~7V~3 130. The pre-iynited incendiary Eluld will thus discharge rom -the discharcJ~ por-ts 130 at tremendous pressures and velocity as well as at high temperatures. The discharging fluid will then strike -the pipe wall or tubing 155 opposite the ends of ! the passages, whereln -the fluid will react with the pipe wall which will be burned or dissolved effecting the desired cutting result.
It may be seen that -the pressure oE the propellant gases l causing the slips 86 to deploy outwardly into the tubiny 155 ¦ has securely lodged the tool 10 within the wellbore. It may also be seen that the tool 10 will remain lodged within the wellbore unless the slips 86 are suitably retracted. For this reason, when the propellant gas pressure is substantially ¦ vented the biasing force of the spring 60 returns the slip ¦ housing to its upright position whereby the slips 86 are separated from around the mandrel 90. In the retracted position ~he slips 86 are automatically retracted from the side walls of the tubing 155 under the tension of the garter spring 1 96 disposed therearound. Once the slips 86 assume their I retracted position the tool 10 may be removed from the borehole ¦ by pulling it upwardly. Likewise it may be recharged for subsequent usage.
i In the alternative struc-tural embodiment of the tool 10 l shown in FIGS. 12 and 13, it may be seen that the identical ¦¦ procedural steps are required to activate the tool 10 to effec-t cutting in the borehole. However, the specific operation of the slip assembly 1~ is effected by an upward driving of the slips against the rnandrel 92 i.n that the slip assembl~ module 1~ has been inverted. In all other respects, th~. operation of the tool 10 is the same as described above, with the exception that during removal should slip retraction become a problem, an upward tugging on the supporting cable wil]. permit the mandrel 92 -to be pulled from beneath the base of the slips 86 to permit said slips to return to their initial position. In like manner, the garter spring 96 then serves as a biasinc3 I element for returning the slips 86 to their initial position.
10 Should the slips ~6 yet ~ail to retract for any reason, the tool 10 maY still be removed from the borehole as set forth above. More particularlv, the chamfer 170 of the slip structure sho~n in FIG~ 12 Permi.ts the slip to be "draqcled" upwardly in a "sled" fashion This desiqn aspect may thus be seen to add another utili-ty dimension to the particular confiquration of the cvlindrically seqmented S].iP arraY set for-th in the present invention-¦ It is therefore believed that the operation and construc l¦tion of the above-described invention will be apparent from Ithe foreqoinq description. While the method and apparatus for ¦chemical cuttinq in a borehole shown and described has been characterized as beinq preferred, it will be obvious that ;Ivarious chanqes and modifications may be made without departinq Ifrom the spirit and the scope of the invention as defined in the f~llowincl claims.
1.
Il .,
Claims (11)
1. A downhole chemical fluid jet cutting tool adapted to he suspended from an electrical wireline comprising in combination:
(a) an elongated generally cylindrical tool body;
(b) a generally cylindrical slip body means form-ing part of said tool body and comprising a pipe gripping slips array connected into a fluid pressure responsive co-axially disposed expand-able piston-cylinder means;
(c) said piston-cylinder means being biased toward a retracted position by elastic return means;
(d) each slip of said slips including a head at a first end being retained by said slip body and being biased toward a retracted position from a deployed position by positive retraction means;
(e) said piston-cylinder means including a slip expansion mandrel means disposed within said slip array to deploy said slips into gripping engagement as said piston-cylinder is actuated against said elastic return means in response to application of fluid pressure;
(f) a chemical fluid cutting means forming part of said tool body including a fluid chamber adapted to contain a fluid chemical defined within said tool body between two diaphragm means provided to rupture from application of a designated differential fluid pressure;
and (g) a fluid jet discharge means formed in said tool body and adapted to direct fluid chemical from said tool body in selected direction and at high velocity.
(a) an elongated generally cylindrical tool body;
(b) a generally cylindrical slip body means form-ing part of said tool body and comprising a pipe gripping slips array connected into a fluid pressure responsive co-axially disposed expand-able piston-cylinder means;
(c) said piston-cylinder means being biased toward a retracted position by elastic return means;
(d) each slip of said slips including a head at a first end being retained by said slip body and being biased toward a retracted position from a deployed position by positive retraction means;
(e) said piston-cylinder means including a slip expansion mandrel means disposed within said slip array to deploy said slips into gripping engagement as said piston-cylinder is actuated against said elastic return means in response to application of fluid pressure;
(f) a chemical fluid cutting means forming part of said tool body including a fluid chamber adapted to contain a fluid chemical defined within said tool body between two diaphragm means provided to rupture from application of a designated differential fluid pressure;
and (g) a fluid jet discharge means formed in said tool body and adapted to direct fluid chemical from said tool body in selected direction and at high velocity.
2. The cutting tool of claim 1. wherein each of said slips defines at least two sets of gripping teeth having different gripping faces defined by said gripping teeth such that each gripping face becomes substantially parallel with the axis of said tool body as each of said slips becomes deployed a different respective distance from said tool body.
3. The cutting tool of claim 1. wherein said tool body is provided with fluid pressure generating means adapted to contain and ignite a gas generating propellant for gener-ating fluid pressure to deploy said slips into pipe gripping position, to rupture said diaphragms, to release said fluid chemical, and to force said fluid chemical from said fluid jet discharge means.
4. The cutting tool of claim 1. wherein each of said diaphragms is formed with a cross-sectional rupture area defined along at least one line extending across said diaphragm and provided to rupture responsive to a closely designated differential fluid pressure applied across said diaphragm.
5. The apparatus of claim 1. wherein said cutting tool includes an ignitor means disposed to cause an incendiary reaction of chemical fluids passing from said fluid chamber to said jet cutting means.
6. The cutting tool of claim 1. wherein the cross-sectional area of each of said rupture diaphragms is provided to be ruptured by a fluid pressure differential closely designated within the range of 500 psi and 3,500 psi to cause said cutting tool to be operative in a safe and predictable fashion.
7. The cutting tool of claim 3. wherein each of said slips defines at least two sets of gripping teeth having different gripping faces defined by said gripping teeth such that each gripping face becomes substantially parallel with the axis of said tool body as each of said slips becomes deployed a different respective distance from said tool body.
8. The cutting tool of claim 7. wherein each of said diaphragms is formed with a cross-sectional rupture area defined along at least one line extending across said diaphragm and provided to rupture responsive to a closely designated differential fluid pressure applied across said diaphragm.
9. The cutting tool of claim 8. wherein the cross-sectional area of each of said rupture diaphragms is provided to be ruptured by a fluid pressure differential closely designated within the range of 500 psi and 3,500 psi to cause said cutting tool to be operative in a predictable manner.
10. The apparatus of claim 9. wherein said cutting tool includes an ignitor means disposed to cause an incendiary reaction of chemical fluids passing from said fluid chamber to said jet cutting means.
11. The cutting tool combination of claim 1. wherein the slips of said array each have at least two gripping teeth angulation patterns such that: (a) the outer extremities of first teeth of a first angulation pattern define a first line disposed in a plane related to the axis of said tool such that said first line defines a first acute angle with said tool axis when said first teeth are not deployed and such that said first line is disposed substantially parallel to said tool axis when said first teeth are deployed a first distance from said tool axis;
and (b) the outer extremities of second teeth of a second angulation pattern define a second line disposed in a plane related to said tool axis such that said second line defines a second acute angle with said tool axis when said first teeth are not deployed, said second acute angle being different from said first acute angle, and such that said second line is disposed substantially parallel to said tool axis when said second teeth are deployed a second distance from said tool axis, said second distance being different from said first distance.
and (b) the outer extremities of second teeth of a second angulation pattern define a second line disposed in a plane related to said tool axis such that said second line defines a second acute angle with said tool axis when said first teeth are not deployed, said second acute angle being different from said first acute angle, and such that said second line is disposed substantially parallel to said tool axis when said second teeth are deployed a second distance from said tool axis, said second distance being different from said first distance.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000408332A CA1170163A (en) | 1982-07-29 | 1982-07-29 | Apparatus for chemical cutting |
| CA000445582A CA1184843A (en) | 1978-02-13 | 1984-01-18 | Apparatus for chemical cutting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000408332A CA1170163A (en) | 1982-07-29 | 1982-07-29 | Apparatus for chemical cutting |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000445582A Division CA1184843A (en) | 1978-02-13 | 1984-01-18 | Apparatus for chemical cutting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170163A true CA1170163A (en) | 1984-07-03 |
Family
ID=4123306
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408332A Expired CA1170163A (en) | 1978-02-13 | 1982-07-29 | Apparatus for chemical cutting |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1170163A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112894895A (en) * | 2020-12-25 | 2021-06-04 | 中国船舶重工集团有限公司第七一0研究所 | Submarine optical cable shears |
-
1982
- 1982-07-29 CA CA000408332A patent/CA1170163A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112894895A (en) * | 2020-12-25 | 2021-06-04 | 中国船舶重工集团有限公司第七一0研究所 | Submarine optical cable shears |
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