CA1184843A - Apparatus for chemical cutting - Google Patents
Apparatus for chemical cuttingInfo
- Publication number
- CA1184843A CA1184843A CA000445582A CA445582A CA1184843A CA 1184843 A CA1184843 A CA 1184843A CA 000445582 A CA000445582 A CA 000445582A CA 445582 A CA445582 A CA 445582A CA 1184843 A CA1184843 A CA 1184843A
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- Canada
- Prior art keywords
- tubing
- slip
- tool
- assembly
- slips
- Prior art date
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Abstract
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.
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
This invention relates to downhole well tools and more particularly to anchoring systems for downhole well tools especially suitable for employment in chemical cutting tools.
Such chemical cutting tools may be of a type employi~g a chemical cutting fluid of highly reactive incendiary character such that when brought into contact with tubing susper,ded 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 where 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 cut~ers and chemical cutters. There are problems associated with shaped charge cutters, however, because a tubing string into which the cutter can be lowerPd into the wellbore, often contains a pump seating nipple or landing nipple which forms 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
IL18~ 3 I to be partially recovered, the force generated by an explosion ¦ of a shaped cnarge in the tubing cutter causes parts of the ¦ cutter which are not disintegrated to become eY~panded or I the end of the tubing to become flared. This expansion often ¦ times prevents the retrieval of the expanded part.
Chemical cutters have been shown to be very reliable while 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 I damage to ~he adjacent string of ~ubing. One such prior art ¦ construction is shown and described in U. S. Pats. 2,918,125, ~¦ issued December 22, 1959 and 3,07~,507, issued February 5, 1 1963, both to William G. Sweetman. As set forth in the ¦! Sweetman Patents, the cutting fluids employed in accordance ,j with that invention are fluids which are extremely active chem- !
ically and which when brought into contact with most oxi- I
dizable substances, react violently therewith generatiny ex- ¦
tremely high temperatures sufficient to melt, cut or burn the ad~acent tubing. Fluids such as halogenflourides, including cholorine tri-flouride as well as bromine tri-flouride have I been proven to be effective in tubing cutting.
ll There are several considerations which remain of major ¦ import in the utilization of such chemical cutters as set forth Il above. First, the secure anchoring, or downhole positioning I of the cutter within the wellbore is a major consideration. The cutter must be fixedly positioned within the wellbore so as to make a uniform cut and to prevent the flaring or creation ~, _3_ ~ 3 of debris within the wellbore to frustrate the attempt of an effective cutting operation- The rigidity of the anchoring and centralized positioning is thus of critical im~ort. It is aiso necessary that ~he overall unit be functionally reliable, I including sure ignition, positive fluid seals and environmental ¦ durability. For example, the insertion of the tool into the ¦¦ wellbore is coincident with immersion in those fluids normally present therein such as mud and sand. It is thus important that ¦
I such substances do not adversely affect the operation of the I subject tooling.
It would be an advantage therefore to provide a chemical tubing cutter which would overcome many of the problems of the prior art wherein the tubing cutter could be reliably and ¦ securely positioned within the wellbore for the cutting oper-1l ation. It would be a further advantage to provide a single tubing cuttex secura~le within known conduits of a different size while eE~ecting the equivalent reliability. The method and I apparatus of the present invention includes such a chemical ¦I tubing cutter wherein a multi-angulated slip assembly is utilized 20 ¦I for circumferential en~agement within tubing of different sizes.
The tu~ing cutter of the present invention also provides a means for the reliable sealing, ignition and actuation of the in-cendiary elements therein for the proper maintenance and control Il thereof.
25 1I SUMMAR~ OF THE_INVENTION
This invention relates to an elongated generally cylindrical downhole tool and anchoring means therefore which may ¦l be employed in chemical cutting systems. The downhole tool of Il the present invention is a generally cylindrical structure 1' Il comprising anchoring means for releasably anchoring the tool in a centralized position against the wall of a pipe within a well.
The anchoring means comprises a plurality of gripping slips that mounted at one end to a first structural element. The other ends of the gripping slips are internally tapered for longitudinal movement upon a frustoconical mandrel whereby the slips are deployed outwardly. The slips have an arcuate cross sectional configuration so that the interior of the array i5 generally cylindrical when the slips are not deployed. The gripping teeth of the slips are arranged in at lea~t two discreet longitudinally e~tending angulation patterns which define different acute angles with the axis of the tool. A first angulation pattern is disposed so that the teeth are disposed substantially parallel to the tool axis at a distance to engage a first tubing diameter. A
second angulation pattern is set at a different angle so that it will be substantially parallel with the tool axis at a different distance to engage a second tubing diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
~or a more complete understandin~ of the present inven-tion and for further objects and advantages thereof, referencemay now be had to the following description taken in conjunc-tion with the accompanying drawings, in which:
FIGS. 1 through 5, together, comprise a longitudinal, cross-sectional, side-elevational view of one embodiment of a chemical cutting apparatus constructed in accordance with the principles of the present invention, illustrating an array of propellant, chemical, 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 tubinq cutter assembly of FIG~ 3 taken~long lines 6-6 thereof and illustrating ~he cylindrically 1'1 8484;~
I segmer.ted gripping slips assembled therearound;
¦I FIG. 7 is an enlarged, side-elevational view of an in-¦' dividual s~.ip from the slip array of FIG. 3, illustrating the I gripping teeth formed with two discrete angulation patterns;
1 ~IG. 8 is a fragmen~ary side-elevational, cross-sec-tional view of a slip assembly in an outwardly deployed configu-¦l ration engaging the side wall of tubing in a borehole;
FIG. 9 is an enlarged top plan view of a rupture dia-Il phragm of the chemical module of FIG. 4;
lC ! FIG. 10 is a side-elevational, cross-sectional view of the rupture diaphragm of FIG. 9, taken along lines 10-10 thereof;
FIG. 11 is an enlarged perspective view of a rupture !i diaphragm illustrating the ruptured configuration thereof for ¦ providing a substantially full flow opening; and FIGS. 12 and 13 comprise a longitudinal, cross-sectional ¦
side-elevational view of an alternative embodiment of the slip ¦ assembly module of the present invention.
¦ DETAILED DESCRIPTION
ll Referriny first to FIGS. 1 through 5, there is shown a I CUttillg tool designated generally by the number 10, which is inserted in a string of tubing (not shown) extending into a wellbore which may be lined with a metal casing (not shown).
I The cuttin~ tool comprises in downwardly arranged succession, a I propellant module assembly 12, a slip assembly 14, a chemical ,. module assembly 16, and a discharge head assembly 18. These ¦I several modules, which are constructed of suitably strong material such as steel, are generally cylindrical and connected 11841~43 ¦ together in end-to-end coaxial relation. The modular array forms an elongated cylindrical tool 10 of substantially uniform exterior diameter, which is adapted for in~ertion into the tubing string on the end of a flexible cable, or the like (not I shown). A head assembly 20, is connected to the upper end of the cutting tool 10 and includes a socket 22 of generally con-ventional form which connects tl)e upper end of the tool 10 to the tool string or cable which is employed for lowering and raising said tool in the wellbore. The aforesaid tool string or cable, although not shown, includes means for transmitting an electric current from a conventional source about the well-ll bore to the tool 10 for the operation thereof.
¦I Referring particularly now to FIG. 1 there is shown the ¦ propellant module assembly 12 disposed beneath and secured to ¦ the head assembly 20. Interconnecting the head assembly 20 I and the prope:llant 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 I plug 30 is constructed atop the electrode 26 for electrical ¦¦ communication with the surface above the borehole. Immediately 'I beneath the electrode 26 and the firing sub 24, there depends a fuse assembly 32 including an explosive initiator element Il 34 of generally conventional design. The fuse assembly 32 being ¦¦ placed in electrical contact with the end of the electrode 26 ~I provides means for igniting a controlled burning propellant ¦ disposed therebelow. A longitudinal passage 36 provides com- I
¦! munication between the initiator cap 34 and a propellant chamber ¦
37 formed in the propellant module assembly 12. The module i I
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j 12 includes an outer sleeve 38 coupled to the fuse assembly via I a threaded coupling 40. It should be noted ~hat the various ¦ modules and suhassemblies described herein, are conventionally Il coupled one to the other by threaded couplings and sealed with 1¦ O-rings positioned therewithin. The threaded couplings and 0-~¦ rings are not 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 containins a propellant l housing, or spacer 46 havins a plurality of ports 48 formed along ¦ the length thereof. The propellant 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-Il pellant gas.
¦ Referring now to FIG. 2, there is shown the lot~er part of the propellant assembly 12 and particularly the lo~er region I of the power charge sleeve 46 con~aining the propellant therein.
¦ ~ suitable annular region may be provided around the propellant ¦! spacer 46 and within the tubular bore 44 ol the propellant 20 ¦¦ chamber 37 as shown for the generation of suitable pressurizing ~ gases therein. The gases generated in the propellant assembly ;¦ 12 are allowed to escape downwardly into the lower slip asse~ly ¦
¦l 14 for actuation thereof via a tubular bore 52 constructcd ¦¦ beneath the propellant chamber 37 in an upper region of the slip ij 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 14 and includes a central bore 58 formed I
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~L1 8~843 therethrough in abutting communication with the slip sub passage 52 for permitting the propellant gases to escape there-through.
Referring now to the lower region of the tool 1~
¦ illustrated in FIG. 2, there is shown a cylindrical housing !1 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 therein. The sprin~
¦ 60 circumferentially encompasses the slip shaft 56 longitudinally I therealong longitudinally biasing the slip housing 62 upwardly against the upper slip sub 54 Referring now to FIG. 3, there is 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 may be seen to ¦ include a lower seating flange 66 for receiving the base of the spring 60 thereagainst. The flange 66 inclues a circumferen-I tial slotted portion 68 containing an O-riny 70 therein for ¦ purposes of sealing the slip shaft 56 relative to the slip ¦I housing 62. ~ piston-cylinder configuration is thus constructed ¦
I between the slip shaft 56 and slip assembly housing 62 respec-tively. Beneath the flange or piston 66 the central passage 58, j extending through the slip shaft 56, is vented through venting ports 72 extending transversely therefrom and in communication I with the passage 58 for venting a lower, annular space 7g beneath I the flange 66. The slip housing 62 is constructed with a lower ¦ flange bulkhead 76 containing an O-ring 78 ~herewithin and around the slip shaft 56 for sealing the said housing thereagainst.
Il _9_ 118484~
In this manner, propellant gases escaping through the passage 58 will be vented into the annular space 74 for creating a ¦ pressure against the seating flange 66 and causing the slip ¦ assembly housing 62 to be driven downwardly along the slip ¦ shaft 56, against the biasing compression of the spring 60.
¦I Referring now to the lower region of FIG. 3, there is shown the lower portion of the slip assembly housing 62 con-¦I structed with a partially open-ended annulus 80 constructed ¦ therein. A lower contrally aperture flange 82 forms the base ~0 jl portion of the annulus 80 and receives the upper head section ¦l 84 of an array 85 of gripping slips 86 pivotally seated therein ¦l 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 securely grip 1¦ the wall of adjacent tubing as will be described in more detail below. I
ll A plurality of slips are provided around the sli~- !
¦I shaft 56, each heing constructed with a lower, internally jl tapered end 90. The end 90 of each slip 86 is adaptcd for ¦1 abutting a cornplementally tapered frusto-conical mandrell 92 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 Il 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, !
'j angular deployment of the slips 86 for anchoring against the adjacent tubing. The slipshaft 56 may be seen to be struc-turally interconnected with the lower slip sub 94 through a 11 , r`
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threaded interconnection therebetween. Spring means 96 such as "garter s~rings" are provided around the slips 86 through a slotted portion 100 formed above the teeth 88. The spring I means ~6 may include any suitable elastic material or spring I construc,tion sufficient to lightly bias the slips 86 in the j closed position shown.
~Referriny now to FIG. 4, there is shown the lowermost portion of the slip assembly module 14 wherein the passage 58 I¦ of the slipshaft 56 communicates with a central bore 102 formed !~ within the lowex slip sub 94. The bore 102 comprises a passage Il for the egress of propellant gases from the passage 58 into the ¦1 lower chemical module 16. The chemical'module 16 is connected Il to the slip assembly module through a sealed interconnection jl 104, wherein means are constructed for sealably containing the 1, select incendiary fluid stored in said chemical module.
gasket 106 ls thus provided beneath the passage 102 atop a diaphragm retainer 108 abutting a rupture diaphraym 110. The diaphragrn 110 is constructed with an area of reduced cross-I section for rupturing at a predefined fluid pressure differen-I t-'al thereacross in a manner to completely open the flow passage therethrough as will be described in more detail below. The , diaphragm 110 seals a fluid chamber 112 centrally bored within the chemical module 16 therein containing a selected incendiary ' fluid 111. The term incendiary chemical is used herein as ~¦ referriny to a highly reactive chemical which is particularly jl adapted for such downhole CUttinCJ operation. In particular, Il bromine tri-flouride has been found to be acceptable as an ~' l !
ll ~L184~3 ¦ incendiary fluid for cutting operations in accordance with the teachings of the present invention. The aforesaid incendiary fluid is further contained within the chamber 112 by a lower rupture diaphragm 110. Likewise, a diaphraym retainer 116 and ! gasket 118 are provided therebeneath for the securement and sealing 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 I cause the rupturing of the rupture diaphragm 110, forcing the j incendiary fluid 111 within chamber 112 downwardly, rupturing l¦ the lower rupture disc 110 for passage into an igniter sub ¦¦ 120 partially housing within the chemical module assembly 16.
¦I The ignitor sub 120 is threadably coupled to the chemical ¦I module 16 and is construoted with a central chamber 122 con-1I taining steel wool 123 which may be coated with oil, or a ¦ similar product s~litable for reaction with the respective in-cendiary fluid utilized. The steel wool 123 promotes a violent reaction when it contacts the downwardly egressing incendiary Il fluid 111 for the generation of further pressure and activity.
~l A lower longitudinal passage 124 is constructed beneath the ¦I chamber 122 in communication therewith for the escape of the ! activated incendiary fluid 111.
! Referring now to FIG. 5, there is shown the lower por-¦l tion of the igniter sub 120 and the passage 129 extending there-1I through and communica~ing with a discharge head piston 126 Il positioned within the discharge head module 18. The piston ¦ 126 is slidably mounted within an axial bore 126 constructed i ~ 3 within the discharge head housing 129, which is formed with a I plurality of radially extending venting ports or jets 130 extending outwardly of the central bore 128. ~he ~iston 126 is mounted within the bore 128 for downward movement and is suitably sealed therein with a plurality of smaller O-rings 132 secured therearound hoth above and below the discharge ports 130.
Proper sealing of the piston is necessary to ensure the noncon-I tamination of the tool 10 from well fluids during insertion j within a wellbore.
I The dischaxge head module 18 includes a lower bullnose 134 depending fxom and threadably coupled to the housing 129.
, The bullnose 134 forms the lower end of the tool 10. The bull-nose is comprised of a generally cylindrical section having j axial bore 136 constructed for receiving the piston 126 once ¦ said piston is driven downwardly by the pressure of the pro-pellant and fluid generated thereabove.
! The bullnose ~4 is coupled to the disc}large head housing Il 129 with a support washer 138 lodged therebetween. The support ¦I washer 138 is constructed with a central aperture 140 having 11 a diameter small enough to retain the piston 126 thereabove. I
The washer 138 is also constructed of sufficiently thin material ¦
to deform and/or shear under preselected forces to permit the downward movement of the piston 126 under pressure of the ¦~ escaping incendiary fluid 111. The downward movement of the ¦ piston 126 into the chamber 136 of the bullnose 134 opens the chamber 128 to the discharge ports 130, permittin~ the incen~
diary ~luid 111 to jet therethrough. The discharge ports 130 are constructed in a radially extending pattern (not shown), ~1 1 i ll -13-1~
1~L848d~3 which pattern is of conventional "overlap" design. An "~verlap"
pattern is one wherein fluid spray of adjacent discharge ports is contiguous UPOn the surface being cut so that the incen-l diary fluid discharged from said adjacen-t ports forms a sub-¦I stantially continuous cut pattern.
j Referring now to FIG. 6, there is shown a top plan view of the slip assembly l~ of FIG. 3 taken along lines 6-6 thereof and more clearly illustrating the positioning of the slips 86 l¦therealong. In the tool lO 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-Iment from the slip shaft 56. The term "cylindrically\ segmented"
¦lis hereinaft~r utili~ed in referring to the particular slip ¦!assembly array 85 of the present invention. The cylindrically ¦jsegmented 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 ho~sing llconfiguration. 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 effect an assembly wherein the slips 86 ¦¦are locked into place, one against the other. The outward lldeployment of the slips 86, with ~he head sections 84 pivoting ¦,within the annulus 90, then permits engagement of the adjacent tubing with maximum gripping effectiveness for secure anchcring ,thereag~inst. Additionally, the segmented, cylindrical con-igaration of thc slips array 86 ensares the centralization of 11t~4~43 the tubiny cutter 10 within the wellbore since each slip deploys in a direction opposite to that of an opposing slip, an equivalen~¦
distance, automatically centralizing the position of the tool l 10. Certain prior art constructions have heretofore utilized gripping slips having gripping teeth inscribed upon the outer surface thereof; however, such slips have no~ been provided in the segmented cylindrical array provided herein and in the gripping teeth angulation patterns facilitating multidiameter applications as discussed below.
l Referring now to FIG. 7, there is shown a longitudinal, ¦Icross-sectional elevation of a slip 86 wherein ~he gripping jteeth 88 formed upon the outer surface thereof may be seen in l'more detail. It should be noted that the gripping teeth 88 ¦lof the particular embodiment shown herein are provided in two jldiscrete angulation patterns. These patterns are illustrated by the phantom lines 150 and 152 drawn on the surface of the gripping slip 86. The phantom line 150 illustrates a first angulation pattern for gripping teeth 88 formed on the upper llhalf of the slip 86. The particular construction angle of the ¦Iteeth 88 below line 150 is adapted for uniformly engaging an adjacent tubing wall of a certain diameter upon deployment of the subject slips. Each slip 86 engages the adjacent tubing with equivalent surface area engagement and pressure, due to the !centralizin~ effect of the segmented cylindrical array 85 of the slip assembly 14. The angulation pattern defined by the phantom line 150 may be designed for a particular deployment angle ¦lequivalent to a particular tubing diameter.
34~3 Still referring to FIG. 7, ~hantom line 152 illustrates a second gripping teeth angulation pattern of less acute I construction relative to the central axis of the slip shaft 56.
¦ In this manner, the slip 86 may be deployed at â greater angle ¦ than provided for by said first angulation pattern to uniformly ¦ engage a tubing wall of larger diameter.
Referriny now to FIG. 8, there is shown an example of the aforesaid first and second angulation patterns in engagement ¦
l with a tubing wall and illustrated 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 therein is deployed at the select angle for anchoring tubing of a second larger diameter. It may be seen that if the I tubing 155 were of a smaller select diameter, the upper sec~ion ¦l of the gripping teeth ~8 would engage said tubing with the lower ¦I teeth, beneath phantom line 152 left unengaged. In this manner, ¦l a single cutting tool 10 may be utilized ln boreholes of morc ~¦ than one diameter for cutting operations therein.
l! Referring now to FIGS. 12 and 13 there is shown a ¦1 slightly different embodiment of slip assembly 14. As readily ¦ noted, in these drawings, slip assembly 14 is virtually the same construction as shown in FIGS. 2 and 3 e~cept it is mounted ¦ in an inverted relationship top to bottom in the cutting tool ¦ 10. It may also be seen that the profile of slip 86 and in ¦ particular the gripping teeth 88 is slightly modified relative I to the profile shown in FIG. 3. Accordingly, like elements ¦ of the slip assembly 14 âS shown in FIGS. 2, 3, 7 and 8 bear I the same numbers as the elements shown in FIGS. 12 and 13.
Il I
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~1 ~IL18~843 ¦ The operation of the sllp assembly 14 as shown in FIGS.
~1 2 and 3 is as follows: The gas pressure in space 72 causes the slips to engage the well tubing 155 in which tool 10 is pOSitiGne~ 1, I and therein holdiny the tool 10 immobile until all the liquid ¦ reactive chemical is ejec~ed through the venting ports, or jets, 130 and until the gas pressure is dissipated by egressing behind said liquid through said venting ports. As previously described, after the gas pressure has dissipated, the spring 60 is provided to retract the s.lip assembly 85 away from the walls of the tubing I 155 into its initial retracted position. However, for some I reason should spring 60 not allow the slip assembly ~5 to de-tract, it would be difficult to disengage the slip 86 from the tubing 155. The only possible mechanical manipulation in such a position would be through the cable from which cutting tool~
10 is suspended. The only feasible manner oE disengaqement in this instance is to impart a downward jarring for the tool 10. Wireline jars are available for this purpose but are e~pen-sive and a nuisance to use. It may thus be seen that in the l embodiment of FIGS. 12 and 13, if spriny 60 fails to disen~age l slip assembly 85, a tension applied by upward pull on the wire- ¦
¦l line will draw th~ conical mandrel 92 out from under the slips Il 86 quite readily for facilitating removal of the cutting tool jl. 10 from tubing 155.
¦ At times, the slip retaining means 100 may be damaged 11 or destroyed by flow of the incendiary fluid past assembly 14.
In the situation of FIGS. 2 and 3, such happening is of little ; consequence since the slips 86 tend to pivot inwardly when ~ I
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118484~
cutting tool 10 is pulled upwardly. However, the reverse is evident in the situation of FIGS. 12 and 13. To alleviate hang- ¦
up problems in the tubing, slip 86 of this particular embodiment is provided with a bevel or chamfer 170 as shown. Bevel 170 allows each slip 86 to slide along the tubing wall in "sled"
fashion if slip retaining means 100 becomes inoperable and fails to retract the slip. The gripping teeth 88 are also shown with a slight variation in the profile thereof. As shown in FIG.
7, the gripping teeth 88 are of a "buttress" profile slanting upwardly. In this alternate embodiment the teeth 88 are of equal 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-engaged from embedment in the tubing more easily and also because it also remains firmly engaged by th2 piston 66 until the pro-pellant gas pressure is dissipated through the jets 130 followingj evacuation of the incendiary chemical fluid. This slip also is of dual construction angle as shown by lines 150 and 152 of FIG. 7 shown in FIG. 8.
ll Referring 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, cutting or similar fabrication technique. The area 160 effec-tively ensures the rupture of the djaphragm at a closely pre-selected differential fluid pressure which is an important safety and reliability parameter. The pattern of the area f reduced cross section 160 is shown herein as a cross having a 1~L84~3 ¦central, intcrsectional 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-tersectional 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 isolatt , ¦Itriangular sections 168 therebetween.
!l Referring now to FIG. 11, there is shown a perspective view of a .ruptur~d ductile diaphragm 110 with sections 158 deformed ~¦downwardly, as against the side wails of the chamber 111. It ¦may be seen that this ruptured configuration is the result of ia fluid flow therethrough, either gas or liquid, which fluid flow is essentially unrestricted subsequent to said rupture.
Since the diaphragm llO ruptures in tension along the aforesaid lines 164 and 166, no fragments of the rupture diaphragm 110 are left in the tool 10 to interfere with fluid flow. This aspect is critical to maximum efficiency and safety of the tool 1¦10 and is herein referred to as a substantially complete, un-¦I fragmented rupture.
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 propellent ll50 to properly operate cutting tool lO. Such lower pressures ¦ of course increase the safe handling of the tool in or out of the wellbore. ~lso, as outlined below, such lower pressures are considered to enhance the cutting action of the reaction product 1f the incendiary fluid 111.
il l!
I ~he diaphragm 110, when constructed as described with ¦I reference to FIGS. 9 and 10, can be p~ovided to rupture t~ithin a close pressure range, 100 psi for example, from about 500 to 4,000 psi differential pressure ~and above though such higher I pressures would never be needed in the tool of the present ¦l inYention) The present cutting tool 10, which may be built in ¦ various sizes, is presently used in rnost instances with the Il rupture disc 110 havinq a rupture pressure in the ran~e of about ¦1 1,000 to 2,500 psi differential pressure, though the pressures ¦ may qo hi~her or lower at times depending on different factors.
ll ~eferring now to FIGS. 1-5, the complete in~erior of ¦¦ cutting tool 10 is at atmospheric pressure until the tool 10 is lowered to the selected position in well conduit 155 and the ¦I propellant 50 ignited. There is generally a small air space ¦I below the top of upper diaphragm 110 and the incendiary liquid 111. The cavity 122 also contains some air. As an illustrative description, when the propellant S0 is ignited it continues to burn and produce gas until expended. The amount of propellant ~' is provided in sufficient quantity to eventually reach a pressure li sufficiently higher than the pressure inside tubing 155 to 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.
I Assuming that both the diaphragms llO are provided to ¦ rupture at 1,500 psi differentlal pressure, the gas pressure ¦ generated by propellant 50 ruptures first the top diaphragm then I the lower diaphragrn-llO in very close succession, forcing the a8~3 I
incendiary chemical 111 into chamber 122 with the reaction product such as the steel wool given as an example. The reaction may produce additional gas pressure, dependinq on the reactive com-l ponents provided.
I The support washer 139 may be provided of thickness to ¦permit piston 126 to clear ports 130 immediately or of greater ¦thickness to provide time for creating more or less pressure and reaction product before deforminy or shearing to allow the reaction product to be jetted by the gas pressure through ports 130 against the walls of tubing 155. When the ports 130 are Icleared for passage of the reaction product, the pressure of the ¦Icompressihle gas within tool 10 should then be adequately greater than the pressure within tubing 155 to immediately permit the good jetting action previously described. Though the real ¦ pressure within the tool 10 may become quite high during the l getting of all the reaction product, the differential pressure !¦ between the interior and exterior of tool 10 need not be greater ¦than necessary to produce the good jetting action as previously Idescribed. Thus, if the tool were inadvertantly activated at the earth's surface or in a dry hole, the differential pressure utilized for the jetting predictably would remain relatively low ¦and more safe and consistent.
i 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, and incendiary chemical and assembled as illustrated in FIGS. 1 through 5. The I
¦ tool 10 is then connected to a suspension cable and lowered into the tubing 155 to the point at which the cut is to be made. The tool 10 is next firmly anchored to the tubing wall by the con-trolled ignition of the propellant assembly 12. The propellant assembly is activated by the detonation of the firing sub 24 and fuse 32 through electrical communication from the surface of the borehole. The electric current may be provided from any suitable and conventional source (not shown~. The ignition of the fuse 32 then ignites the propellant whereby gas pressure I is created. The gas egresses downwardly into the slip assembly ¦ 14 and into the slip assembly housing 62. The slip housing 62 I moves downwardly along the slip shaft 56 pushing the slips 86 ¦ against the mandrel 92 causing the slips to deploy outwardly into I the adjacent tuhing 155. The tool 10 is now securely anchored I in a centralized configuration within the borehole.
The propellant gas within the now anchored tool 10 continues to build up from the gases produced by the propellant sub 12 until the upper diaphragm 110 atop the chemical module 111 ¦l is ruptured. The rupture of the upper diaphragm 110 causes the incendiary fluid contained therein to move 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 steel wool therebelow.
¦¦ The incendiary fluid is activated in the ignitor hair, with a ¦ 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 130. The pre-ignited incendiary fluid will thus discharge from the discharge ports 130 at tremendous pressures and velocity as well as at high temperatures. The discharging fluid will then strike tAe pipe wall or tubing 155 opposite the ends of 1 the passages, wherein 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 of the propellant gases l causing the slips 86 to deploy outwardly into the tubing 155 ~ has securely lodged the tool 10 within the wellbore. It may I also be seen that the tool 10 will remain lodged within the ¦ wcllbore unless the slips 86 are suitably retracted. For this I reason, when the propellant gas pressure is subctantially ¦ vented the biasing force of the spring 60 returns the slip I housing to its upright position whereby the sllps 86 are separated from around the mandrel 90. In the retracted position I the slips 86 are au~omatically retracted from the side walls of the tubing 155 under the tension of the garter spring 96 disposed therearound. Once the slips 86 assume their I retracted position ~he tool 10 may be removed from the borehole ¦ by pulling it upwardly. Likewise it may be recharged for subsequent usage.
jl In the alternative structural embodiment of the tool 10 Il shown in FIGS. 12 and 13, it may be seen that the identical ¦ procedural s~eps are required to activate the tool 10 to effect cutting in the borehole. However, the specific operation of the slip assembly 14 is effected by an upward driving of the 11~4~3 slips against the mandrel 92 in that the slip assembly module 14 has been inverted. In all other respects, the operation of the tool 10 is the same as described above, with the exception that during removal should slip retraction become a problem, 1 an upward tugging on the supporting cable will permit the mandrel 92 to be pulled from beneath the base of the slips 86 to permit said slips to return to thei7 initial position. In like manner, the garter spring 96 then serves as a biasing I element for returning the slips 86 to their initial position.
Should the slips 86 yet fail to retract for any reason, the tool 10 mav still be removed from the borehole as set forth above. More particularly, the chamfer 170 of the slip structure shown in FIG. 12 permits the slip to be "dragged" upwardly in a "sled" fashion. This design aspect may thus be seen to add another utility dimension to the particular confiyuration of the ¦cylindrically se~mented slip array set forth in the present ! inventiOn, It is therefore believed that the operation and construc~
l¦tion of the abovP-described invention will be apparent from Ithe foregoing description. While the method and apparatus for chemical cutting in a borehole shown and described has been ;characteriæed as being preferred, it will be obvious that various changes and modifications may be made without departing lifrom the spirit and the scope of the invention as defined in j,the following claims.
I _~9_ 1, 1, I
Such chemical cutting tools may be of a type employi~g a chemical cutting fluid of highly reactive incendiary character such that when brought into contact with tubing susper,ded 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 where 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 cut~ers and chemical cutters. There are problems associated with shaped charge cutters, however, because a tubing string into which the cutter can be lowerPd into the wellbore, often contains a pump seating nipple or landing nipple which forms 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
IL18~ 3 I to be partially recovered, the force generated by an explosion ¦ of a shaped cnarge in the tubing cutter causes parts of the ¦ cutter which are not disintegrated to become eY~panded or I the end of the tubing to become flared. This expansion often ¦ times prevents the retrieval of the expanded part.
Chemical cutters have been shown to be very reliable while 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 I damage to ~he adjacent string of ~ubing. One such prior art ¦ construction is shown and described in U. S. Pats. 2,918,125, ~¦ issued December 22, 1959 and 3,07~,507, issued February 5, 1 1963, both to William G. Sweetman. As set forth in the ¦! Sweetman Patents, the cutting fluids employed in accordance ,j with that invention are fluids which are extremely active chem- !
ically and which when brought into contact with most oxi- I
dizable substances, react violently therewith generatiny ex- ¦
tremely high temperatures sufficient to melt, cut or burn the ad~acent tubing. Fluids such as halogenflourides, including cholorine tri-flouride as well as bromine tri-flouride have I been proven to be effective in tubing cutting.
ll There are several considerations which remain of major ¦ import in the utilization of such chemical cutters as set forth Il above. First, the secure anchoring, or downhole positioning I of the cutter within the wellbore is a major consideration. The cutter must be fixedly positioned within the wellbore so as to make a uniform cut and to prevent the flaring or creation ~, _3_ ~ 3 of debris within the wellbore to frustrate the attempt of an effective cutting operation- The rigidity of the anchoring and centralized positioning is thus of critical im~ort. It is aiso necessary that ~he overall unit be functionally reliable, I including sure ignition, positive fluid seals and environmental ¦ durability. For example, the insertion of the tool into the ¦¦ wellbore is coincident with immersion in those fluids normally present therein such as mud and sand. It is thus important that ¦
I such substances do not adversely affect the operation of the I subject tooling.
It would be an advantage therefore to provide a chemical tubing cutter which would overcome many of the problems of the prior art wherein the tubing cutter could be reliably and ¦ securely positioned within the wellbore for the cutting oper-1l ation. It would be a further advantage to provide a single tubing cuttex secura~le within known conduits of a different size while eE~ecting the equivalent reliability. The method and I apparatus of the present invention includes such a chemical ¦I tubing cutter wherein a multi-angulated slip assembly is utilized 20 ¦I for circumferential en~agement within tubing of different sizes.
The tu~ing cutter of the present invention also provides a means for the reliable sealing, ignition and actuation of the in-cendiary elements therein for the proper maintenance and control Il thereof.
25 1I SUMMAR~ OF THE_INVENTION
This invention relates to an elongated generally cylindrical downhole tool and anchoring means therefore which may ¦l be employed in chemical cutting systems. The downhole tool of Il the present invention is a generally cylindrical structure 1' Il comprising anchoring means for releasably anchoring the tool in a centralized position against the wall of a pipe within a well.
The anchoring means comprises a plurality of gripping slips that mounted at one end to a first structural element. The other ends of the gripping slips are internally tapered for longitudinal movement upon a frustoconical mandrel whereby the slips are deployed outwardly. The slips have an arcuate cross sectional configuration so that the interior of the array i5 generally cylindrical when the slips are not deployed. The gripping teeth of the slips are arranged in at lea~t two discreet longitudinally e~tending angulation patterns which define different acute angles with the axis of the tool. A first angulation pattern is disposed so that the teeth are disposed substantially parallel to the tool axis at a distance to engage a first tubing diameter. A
second angulation pattern is set at a different angle so that it will be substantially parallel with the tool axis at a different distance to engage a second tubing diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
~or a more complete understandin~ of the present inven-tion and for further objects and advantages thereof, referencemay now be had to the following description taken in conjunc-tion with the accompanying drawings, in which:
FIGS. 1 through 5, together, comprise a longitudinal, cross-sectional, side-elevational view of one embodiment of a chemical cutting apparatus constructed in accordance with the principles of the present invention, illustrating an array of propellant, chemical, 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 tubinq cutter assembly of FIG~ 3 taken~long lines 6-6 thereof and illustrating ~he cylindrically 1'1 8484;~
I segmer.ted gripping slips assembled therearound;
¦I FIG. 7 is an enlarged, side-elevational view of an in-¦' dividual s~.ip from the slip array of FIG. 3, illustrating the I gripping teeth formed with two discrete angulation patterns;
1 ~IG. 8 is a fragmen~ary side-elevational, cross-sec-tional view of a slip assembly in an outwardly deployed configu-¦l ration engaging the side wall of tubing in a borehole;
FIG. 9 is an enlarged top plan view of a rupture dia-Il phragm of the chemical module of FIG. 4;
lC ! FIG. 10 is a side-elevational, cross-sectional view of the rupture diaphragm of FIG. 9, taken along lines 10-10 thereof;
FIG. 11 is an enlarged perspective view of a rupture !i diaphragm illustrating the ruptured configuration thereof for ¦ providing a substantially full flow opening; and FIGS. 12 and 13 comprise a longitudinal, cross-sectional ¦
side-elevational view of an alternative embodiment of the slip ¦ assembly module of the present invention.
¦ DETAILED DESCRIPTION
ll Referriny first to FIGS. 1 through 5, there is shown a I CUttillg tool designated generally by the number 10, which is inserted in a string of tubing (not shown) extending into a wellbore which may be lined with a metal casing (not shown).
I The cuttin~ tool comprises in downwardly arranged succession, a I propellant module assembly 12, a slip assembly 14, a chemical ,. module assembly 16, and a discharge head assembly 18. These ¦I several modules, which are constructed of suitably strong material such as steel, are generally cylindrical and connected 11841~43 ¦ together in end-to-end coaxial relation. The modular array forms an elongated cylindrical tool 10 of substantially uniform exterior diameter, which is adapted for in~ertion into the tubing string on the end of a flexible cable, or the like (not I shown). A head assembly 20, is connected to the upper end of the cutting tool 10 and includes a socket 22 of generally con-ventional form which connects tl)e upper end of the tool 10 to the tool string or cable which is employed for lowering and raising said tool in the wellbore. The aforesaid tool string or cable, although not shown, includes means for transmitting an electric current from a conventional source about the well-ll bore to the tool 10 for the operation thereof.
¦I Referring particularly now to FIG. 1 there is shown the ¦ propellant module assembly 12 disposed beneath and secured to ¦ the head assembly 20. Interconnecting the head assembly 20 I and the prope:llant 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 I plug 30 is constructed atop the electrode 26 for electrical ¦¦ communication with the surface above the borehole. Immediately 'I beneath the electrode 26 and the firing sub 24, there depends a fuse assembly 32 including an explosive initiator element Il 34 of generally conventional design. The fuse assembly 32 being ¦¦ placed in electrical contact with the end of the electrode 26 ~I provides means for igniting a controlled burning propellant ¦ disposed therebelow. A longitudinal passage 36 provides com- I
¦! munication between the initiator cap 34 and a propellant chamber ¦
37 formed in the propellant module assembly 12. The module i I
l I
j 12 includes an outer sleeve 38 coupled to the fuse assembly via I a threaded coupling 40. It should be noted ~hat the various ¦ modules and suhassemblies described herein, are conventionally Il coupled one to the other by threaded couplings and sealed with 1¦ O-rings positioned therewithin. The threaded couplings and 0-~¦ rings are not 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 containins a propellant l housing, or spacer 46 havins a plurality of ports 48 formed along ¦ the length thereof. The propellant 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-Il pellant gas.
¦ Referring now to FIG. 2, there is shown the lot~er part of the propellant assembly 12 and particularly the lo~er region I of the power charge sleeve 46 con~aining the propellant therein.
¦ ~ suitable annular region may be provided around the propellant ¦! spacer 46 and within the tubular bore 44 ol the propellant 20 ¦¦ chamber 37 as shown for the generation of suitable pressurizing ~ gases therein. The gases generated in the propellant assembly ;¦ 12 are allowed to escape downwardly into the lower slip asse~ly ¦
¦l 14 for actuation thereof via a tubular bore 52 constructcd ¦¦ beneath the propellant chamber 37 in an upper region of the slip ij 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 14 and includes a central bore 58 formed I
I - :
~L1 8~843 therethrough in abutting communication with the slip sub passage 52 for permitting the propellant gases to escape there-through.
Referring now to the lower region of the tool 1~
¦ illustrated in FIG. 2, there is shown a cylindrical housing !1 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 therein. The sprin~
¦ 60 circumferentially encompasses the slip shaft 56 longitudinally I therealong longitudinally biasing the slip housing 62 upwardly against the upper slip sub 54 Referring now to FIG. 3, there is 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 may be seen to ¦ include a lower seating flange 66 for receiving the base of the spring 60 thereagainst. The flange 66 inclues a circumferen-I tial slotted portion 68 containing an O-riny 70 therein for ¦ purposes of sealing the slip shaft 56 relative to the slip ¦I housing 62. ~ piston-cylinder configuration is thus constructed ¦
I between the slip shaft 56 and slip assembly housing 62 respec-tively. Beneath the flange or piston 66 the central passage 58, j extending through the slip shaft 56, is vented through venting ports 72 extending transversely therefrom and in communication I with the passage 58 for venting a lower, annular space 7g beneath I the flange 66. The slip housing 62 is constructed with a lower ¦ flange bulkhead 76 containing an O-ring 78 ~herewithin and around the slip shaft 56 for sealing the said housing thereagainst.
Il _9_ 118484~
In this manner, propellant gases escaping through the passage 58 will be vented into the annular space 74 for creating a ¦ pressure against the seating flange 66 and causing the slip ¦ assembly housing 62 to be driven downwardly along the slip ¦ shaft 56, against the biasing compression of the spring 60.
¦I Referring now to the lower region of FIG. 3, there is shown the lower portion of the slip assembly housing 62 con-¦I structed with a partially open-ended annulus 80 constructed ¦ therein. A lower contrally aperture flange 82 forms the base ~0 jl portion of the annulus 80 and receives the upper head section ¦l 84 of an array 85 of gripping slips 86 pivotally seated therein ¦l 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 securely grip 1¦ the wall of adjacent tubing as will be described in more detail below. I
ll A plurality of slips are provided around the sli~- !
¦I shaft 56, each heing constructed with a lower, internally jl tapered end 90. The end 90 of each slip 86 is adaptcd for ¦1 abutting a cornplementally tapered frusto-conical mandrell 92 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 Il 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, !
'j angular deployment of the slips 86 for anchoring against the adjacent tubing. The slipshaft 56 may be seen to be struc-turally interconnected with the lower slip sub 94 through a 11 , r`
I
I
threaded interconnection therebetween. Spring means 96 such as "garter s~rings" are provided around the slips 86 through a slotted portion 100 formed above the teeth 88. The spring I means ~6 may include any suitable elastic material or spring I construc,tion sufficient to lightly bias the slips 86 in the j closed position shown.
~Referriny now to FIG. 4, there is shown the lowermost portion of the slip assembly module 14 wherein the passage 58 I¦ of the slipshaft 56 communicates with a central bore 102 formed !~ within the lowex slip sub 94. The bore 102 comprises a passage Il for the egress of propellant gases from the passage 58 into the ¦1 lower chemical module 16. The chemical'module 16 is connected Il to the slip assembly module through a sealed interconnection jl 104, wherein means are constructed for sealably containing the 1, select incendiary fluid stored in said chemical module.
gasket 106 ls thus provided beneath the passage 102 atop a diaphragm retainer 108 abutting a rupture diaphraym 110. The diaphragrn 110 is constructed with an area of reduced cross-I section for rupturing at a predefined fluid pressure differen-I t-'al thereacross in a manner to completely open the flow passage therethrough as will be described in more detail below. The , diaphragm 110 seals a fluid chamber 112 centrally bored within the chemical module 16 therein containing a selected incendiary ' fluid 111. The term incendiary chemical is used herein as ~¦ referriny to a highly reactive chemical which is particularly jl adapted for such downhole CUttinCJ operation. In particular, Il bromine tri-flouride has been found to be acceptable as an ~' l !
ll ~L184~3 ¦ incendiary fluid for cutting operations in accordance with the teachings of the present invention. The aforesaid incendiary fluid is further contained within the chamber 112 by a lower rupture diaphragm 110. Likewise, a diaphraym retainer 116 and ! gasket 118 are provided therebeneath for the securement and sealing 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 I cause the rupturing of the rupture diaphragm 110, forcing the j incendiary fluid 111 within chamber 112 downwardly, rupturing l¦ the lower rupture disc 110 for passage into an igniter sub ¦¦ 120 partially housing within the chemical module assembly 16.
¦I The ignitor sub 120 is threadably coupled to the chemical ¦I module 16 and is construoted with a central chamber 122 con-1I taining steel wool 123 which may be coated with oil, or a ¦ similar product s~litable for reaction with the respective in-cendiary fluid utilized. The steel wool 123 promotes a violent reaction when it contacts the downwardly egressing incendiary Il fluid 111 for the generation of further pressure and activity.
~l A lower longitudinal passage 124 is constructed beneath the ¦I chamber 122 in communication therewith for the escape of the ! activated incendiary fluid 111.
! Referring now to FIG. 5, there is shown the lower por-¦l tion of the igniter sub 120 and the passage 129 extending there-1I through and communica~ing with a discharge head piston 126 Il positioned within the discharge head module 18. The piston ¦ 126 is slidably mounted within an axial bore 126 constructed i ~ 3 within the discharge head housing 129, which is formed with a I plurality of radially extending venting ports or jets 130 extending outwardly of the central bore 128. ~he ~iston 126 is mounted within the bore 128 for downward movement and is suitably sealed therein with a plurality of smaller O-rings 132 secured therearound hoth above and below the discharge ports 130.
Proper sealing of the piston is necessary to ensure the noncon-I tamination of the tool 10 from well fluids during insertion j within a wellbore.
I The dischaxge head module 18 includes a lower bullnose 134 depending fxom and threadably coupled to the housing 129.
, The bullnose 134 forms the lower end of the tool 10. The bull-nose is comprised of a generally cylindrical section having j axial bore 136 constructed for receiving the piston 126 once ¦ said piston is driven downwardly by the pressure of the pro-pellant and fluid generated thereabove.
! The bullnose ~4 is coupled to the disc}large head housing Il 129 with a support washer 138 lodged therebetween. The support ¦I washer 138 is constructed with a central aperture 140 having 11 a diameter small enough to retain the piston 126 thereabove. I
The washer 138 is also constructed of sufficiently thin material ¦
to deform and/or shear under preselected forces to permit the downward movement of the piston 126 under pressure of the ¦~ escaping incendiary fluid 111. The downward movement of the ¦ piston 126 into the chamber 136 of the bullnose 134 opens the chamber 128 to the discharge ports 130, permittin~ the incen~
diary ~luid 111 to jet therethrough. The discharge ports 130 are constructed in a radially extending pattern (not shown), ~1 1 i ll -13-1~
1~L848d~3 which pattern is of conventional "overlap" design. An "~verlap"
pattern is one wherein fluid spray of adjacent discharge ports is contiguous UPOn the surface being cut so that the incen-l diary fluid discharged from said adjacen-t ports forms a sub-¦I stantially continuous cut pattern.
j Referring now to FIG. 6, there is shown a top plan view of the slip assembly l~ of FIG. 3 taken along lines 6-6 thereof and more clearly illustrating the positioning of the slips 86 l¦therealong. In the tool lO 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-Iment from the slip shaft 56. The term "cylindrically\ segmented"
¦lis hereinaft~r utili~ed in referring to the particular slip ¦!assembly array 85 of the present invention. The cylindrically ¦jsegmented 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 ho~sing llconfiguration. 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 effect an assembly wherein the slips 86 ¦¦are locked into place, one against the other. The outward lldeployment of the slips 86, with ~he head sections 84 pivoting ¦,within the annulus 90, then permits engagement of the adjacent tubing with maximum gripping effectiveness for secure anchcring ,thereag~inst. Additionally, the segmented, cylindrical con-igaration of thc slips array 86 ensares the centralization of 11t~4~43 the tubiny cutter 10 within the wellbore since each slip deploys in a direction opposite to that of an opposing slip, an equivalen~¦
distance, automatically centralizing the position of the tool l 10. Certain prior art constructions have heretofore utilized gripping slips having gripping teeth inscribed upon the outer surface thereof; however, such slips have no~ been provided in the segmented cylindrical array provided herein and in the gripping teeth angulation patterns facilitating multidiameter applications as discussed below.
l Referring now to FIG. 7, there is shown a longitudinal, ¦Icross-sectional elevation of a slip 86 wherein ~he gripping jteeth 88 formed upon the outer surface thereof may be seen in l'more detail. It should be noted that the gripping teeth 88 ¦lof the particular embodiment shown herein are provided in two jldiscrete angulation patterns. These patterns are illustrated by the phantom lines 150 and 152 drawn on the surface of the gripping slip 86. The phantom line 150 illustrates a first angulation pattern for gripping teeth 88 formed on the upper llhalf of the slip 86. The particular construction angle of the ¦Iteeth 88 below line 150 is adapted for uniformly engaging an adjacent tubing wall of a certain diameter upon deployment of the subject slips. Each slip 86 engages the adjacent tubing with equivalent surface area engagement and pressure, due to the !centralizin~ effect of the segmented cylindrical array 85 of the slip assembly 14. The angulation pattern defined by the phantom line 150 may be designed for a particular deployment angle ¦lequivalent to a particular tubing diameter.
34~3 Still referring to FIG. 7, ~hantom line 152 illustrates a second gripping teeth angulation pattern of less acute I construction relative to the central axis of the slip shaft 56.
¦ In this manner, the slip 86 may be deployed at â greater angle ¦ than provided for by said first angulation pattern to uniformly ¦ engage a tubing wall of larger diameter.
Referriny now to FIG. 8, there is shown an example of the aforesaid first and second angulation patterns in engagement ¦
l with a tubing wall and illustrated 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 therein is deployed at the select angle for anchoring tubing of a second larger diameter. It may be seen that if the I tubing 155 were of a smaller select diameter, the upper sec~ion ¦l of the gripping teeth ~8 would engage said tubing with the lower ¦I teeth, beneath phantom line 152 left unengaged. In this manner, ¦l a single cutting tool 10 may be utilized ln boreholes of morc ~¦ than one diameter for cutting operations therein.
l! Referring now to FIGS. 12 and 13 there is shown a ¦1 slightly different embodiment of slip assembly 14. As readily ¦ noted, in these drawings, slip assembly 14 is virtually the same construction as shown in FIGS. 2 and 3 e~cept it is mounted ¦ in an inverted relationship top to bottom in the cutting tool ¦ 10. It may also be seen that the profile of slip 86 and in ¦ particular the gripping teeth 88 is slightly modified relative I to the profile shown in FIG. 3. Accordingly, like elements ¦ of the slip assembly 14 âS shown in FIGS. 2, 3, 7 and 8 bear I the same numbers as the elements shown in FIGS. 12 and 13.
Il I
li I
I
~1 ~IL18~843 ¦ The operation of the sllp assembly 14 as shown in FIGS.
~1 2 and 3 is as follows: The gas pressure in space 72 causes the slips to engage the well tubing 155 in which tool 10 is pOSitiGne~ 1, I and therein holdiny the tool 10 immobile until all the liquid ¦ reactive chemical is ejec~ed through the venting ports, or jets, 130 and until the gas pressure is dissipated by egressing behind said liquid through said venting ports. As previously described, after the gas pressure has dissipated, the spring 60 is provided to retract the s.lip assembly 85 away from the walls of the tubing I 155 into its initial retracted position. However, for some I reason should spring 60 not allow the slip assembly ~5 to de-tract, it would be difficult to disengage the slip 86 from the tubing 155. The only possible mechanical manipulation in such a position would be through the cable from which cutting tool~
10 is suspended. The only feasible manner oE disengaqement in this instance is to impart a downward jarring for the tool 10. Wireline jars are available for this purpose but are e~pen-sive and a nuisance to use. It may thus be seen that in the l embodiment of FIGS. 12 and 13, if spriny 60 fails to disen~age l slip assembly 85, a tension applied by upward pull on the wire- ¦
¦l line will draw th~ conical mandrel 92 out from under the slips Il 86 quite readily for facilitating removal of the cutting tool jl. 10 from tubing 155.
¦ At times, the slip retaining means 100 may be damaged 11 or destroyed by flow of the incendiary fluid past assembly 14.
In the situation of FIGS. 2 and 3, such happening is of little ; consequence since the slips 86 tend to pivot inwardly when ~ I
I!
I
l I
118484~
cutting tool 10 is pulled upwardly. However, the reverse is evident in the situation of FIGS. 12 and 13. To alleviate hang- ¦
up problems in the tubing, slip 86 of this particular embodiment is provided with a bevel or chamfer 170 as shown. Bevel 170 allows each slip 86 to slide along the tubing wall in "sled"
fashion if slip retaining means 100 becomes inoperable and fails to retract the slip. The gripping teeth 88 are also shown with a slight variation in the profile thereof. As shown in FIG.
7, the gripping teeth 88 are of a "buttress" profile slanting upwardly. In this alternate embodiment the teeth 88 are of equal 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-engaged from embedment in the tubing more easily and also because it also remains firmly engaged by th2 piston 66 until the pro-pellant gas pressure is dissipated through the jets 130 followingj evacuation of the incendiary chemical fluid. This slip also is of dual construction angle as shown by lines 150 and 152 of FIG. 7 shown in FIG. 8.
ll Referring 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, cutting or similar fabrication technique. The area 160 effec-tively ensures the rupture of the djaphragm at a closely pre-selected differential fluid pressure which is an important safety and reliability parameter. The pattern of the area f reduced cross section 160 is shown herein as a cross having a 1~L84~3 ¦central, intcrsectional 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-tersectional 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 isolatt , ¦Itriangular sections 168 therebetween.
!l Referring now to FIG. 11, there is shown a perspective view of a .ruptur~d ductile diaphragm 110 with sections 158 deformed ~¦downwardly, as against the side wails of the chamber 111. It ¦may be seen that this ruptured configuration is the result of ia fluid flow therethrough, either gas or liquid, which fluid flow is essentially unrestricted subsequent to said rupture.
Since the diaphragm llO ruptures in tension along the aforesaid lines 164 and 166, no fragments of the rupture diaphragm 110 are left in the tool 10 to interfere with fluid flow. This aspect is critical to maximum efficiency and safety of the tool 1¦10 and is herein referred to as a substantially complete, un-¦I fragmented rupture.
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 propellent ll50 to properly operate cutting tool lO. Such lower pressures ¦ of course increase the safe handling of the tool in or out of the wellbore. ~lso, as outlined below, such lower pressures are considered to enhance the cutting action of the reaction product 1f the incendiary fluid 111.
il l!
I ~he diaphragm 110, when constructed as described with ¦I reference to FIGS. 9 and 10, can be p~ovided to rupture t~ithin a close pressure range, 100 psi for example, from about 500 to 4,000 psi differential pressure ~and above though such higher I pressures would never be needed in the tool of the present ¦l inYention) The present cutting tool 10, which may be built in ¦ various sizes, is presently used in rnost instances with the Il rupture disc 110 havinq a rupture pressure in the ran~e of about ¦1 1,000 to 2,500 psi differential pressure, though the pressures ¦ may qo hi~her or lower at times depending on different factors.
ll ~eferring now to FIGS. 1-5, the complete in~erior of ¦¦ cutting tool 10 is at atmospheric pressure until the tool 10 is lowered to the selected position in well conduit 155 and the ¦I propellant 50 ignited. There is generally a small air space ¦I below the top of upper diaphragm 110 and the incendiary liquid 111. The cavity 122 also contains some air. As an illustrative description, when the propellant S0 is ignited it continues to burn and produce gas until expended. The amount of propellant ~' is provided in sufficient quantity to eventually reach a pressure li sufficiently higher than the pressure inside tubing 155 to 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.
I Assuming that both the diaphragms llO are provided to ¦ rupture at 1,500 psi differentlal pressure, the gas pressure ¦ generated by propellant 50 ruptures first the top diaphragm then I the lower diaphragrn-llO in very close succession, forcing the a8~3 I
incendiary chemical 111 into chamber 122 with the reaction product such as the steel wool given as an example. The reaction may produce additional gas pressure, dependinq on the reactive com-l ponents provided.
I The support washer 139 may be provided of thickness to ¦permit piston 126 to clear ports 130 immediately or of greater ¦thickness to provide time for creating more or less pressure and reaction product before deforminy or shearing to allow the reaction product to be jetted by the gas pressure through ports 130 against the walls of tubing 155. When the ports 130 are Icleared for passage of the reaction product, the pressure of the ¦Icompressihle gas within tool 10 should then be adequately greater than the pressure within tubing 155 to immediately permit the good jetting action previously described. Though the real ¦ pressure within the tool 10 may become quite high during the l getting of all the reaction product, the differential pressure !¦ between the interior and exterior of tool 10 need not be greater ¦than necessary to produce the good jetting action as previously Idescribed. Thus, if the tool were inadvertantly activated at the earth's surface or in a dry hole, the differential pressure utilized for the jetting predictably would remain relatively low ¦and more safe and consistent.
i 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, and incendiary chemical and assembled as illustrated in FIGS. 1 through 5. The I
¦ tool 10 is then connected to a suspension cable and lowered into the tubing 155 to the point at which the cut is to be made. The tool 10 is next firmly anchored to the tubing wall by the con-trolled ignition of the propellant assembly 12. The propellant assembly is activated by the detonation of the firing sub 24 and fuse 32 through electrical communication from the surface of the borehole. The electric current may be provided from any suitable and conventional source (not shown~. The ignition of the fuse 32 then ignites the propellant whereby gas pressure I is created. The gas egresses downwardly into the slip assembly ¦ 14 and into the slip assembly housing 62. The slip housing 62 I moves downwardly along the slip shaft 56 pushing the slips 86 ¦ against the mandrel 92 causing the slips to deploy outwardly into I the adjacent tuhing 155. The tool 10 is now securely anchored I in a centralized configuration within the borehole.
The propellant gas within the now anchored tool 10 continues to build up from the gases produced by the propellant sub 12 until the upper diaphragm 110 atop the chemical module 111 ¦l is ruptured. The rupture of the upper diaphragm 110 causes the incendiary fluid contained therein to move 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 steel wool therebelow.
¦¦ The incendiary fluid is activated in the ignitor hair, with a ¦ 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 130. The pre-ignited incendiary fluid will thus discharge from the discharge ports 130 at tremendous pressures and velocity as well as at high temperatures. The discharging fluid will then strike tAe pipe wall or tubing 155 opposite the ends of 1 the passages, wherein 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 of the propellant gases l causing the slips 86 to deploy outwardly into the tubing 155 ~ has securely lodged the tool 10 within the wellbore. It may I also be seen that the tool 10 will remain lodged within the ¦ wcllbore unless the slips 86 are suitably retracted. For this I reason, when the propellant gas pressure is subctantially ¦ vented the biasing force of the spring 60 returns the slip I housing to its upright position whereby the sllps 86 are separated from around the mandrel 90. In the retracted position I the slips 86 are au~omatically retracted from the side walls of the tubing 155 under the tension of the garter spring 96 disposed therearound. Once the slips 86 assume their I retracted position ~he tool 10 may be removed from the borehole ¦ by pulling it upwardly. Likewise it may be recharged for subsequent usage.
jl In the alternative structural embodiment of the tool 10 Il shown in FIGS. 12 and 13, it may be seen that the identical ¦ procedural s~eps are required to activate the tool 10 to effect cutting in the borehole. However, the specific operation of the slip assembly 14 is effected by an upward driving of the 11~4~3 slips against the mandrel 92 in that the slip assembly module 14 has been inverted. In all other respects, the operation of the tool 10 is the same as described above, with the exception that during removal should slip retraction become a problem, 1 an upward tugging on the supporting cable will permit the mandrel 92 to be pulled from beneath the base of the slips 86 to permit said slips to return to thei7 initial position. In like manner, the garter spring 96 then serves as a biasing I element for returning the slips 86 to their initial position.
Should the slips 86 yet fail to retract for any reason, the tool 10 mav still be removed from the borehole as set forth above. More particularly, the chamfer 170 of the slip structure shown in FIG. 12 permits the slip to be "dragged" upwardly in a "sled" fashion. This design aspect may thus be seen to add another utility dimension to the particular confiyuration of the ¦cylindrically se~mented slip array set forth in the present ! inventiOn, It is therefore believed that the operation and construc~
l¦tion of the abovP-described invention will be apparent from Ithe foregoing description. While the method and apparatus for chemical cutting in a borehole shown and described has been ;characteriæed as being preferred, it will be obvious that various changes and modifications may be made without departing lifrom the spirit and the scope of the invention as defined in j,the following claims.
I _~9_ 1, 1, I
Claims
1. An elongated generally cylindrical downhole tool comprising in combination:
(a) anchoring means for releasably anchoring the tool in a centralized position against the wall of a pipe in a well;
(b) said anchoring means including an array of gripping slips that are pivotally mounted at one end to a first structural element;
(c) said array having a central axis that is coaxial with the axis of said tool;
(d) said gripping slips having internally tapering other end portions for longitudinal movement upon and slidable mating engagement with a frustoconical mandrel for the outward de-ployment of said slips;
(e) said gripping slips having an arcuate cross-sectional configuration so that the interior of said array is generally cylindrical when said slips are not deployed;
and (f) said gripping slips of said array each have at least two gripping teeth angulation patterns such that:
(1.) the outer extremities of first teeth of a first angulation pattern define a first line disposed in a plane related to said tool axis 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 (2.) the outer extremities of second teeth of a second angulation pattern define a second line disposed in a plane re-lated 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.
(a) anchoring means for releasably anchoring the tool in a centralized position against the wall of a pipe in a well;
(b) said anchoring means including an array of gripping slips that are pivotally mounted at one end to a first structural element;
(c) said array having a central axis that is coaxial with the axis of said tool;
(d) said gripping slips having internally tapering other end portions for longitudinal movement upon and slidable mating engagement with a frustoconical mandrel for the outward de-ployment of said slips;
(e) said gripping slips having an arcuate cross-sectional configuration so that the interior of said array is generally cylindrical when said slips are not deployed;
and (f) said gripping slips of said array each have at least two gripping teeth angulation patterns such that:
(1.) the outer extremities of first teeth of a first angulation pattern define a first line disposed in a plane related to said tool axis 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 (2.) the outer extremities of second teeth of a second angulation pattern define a second line disposed in a plane re-lated 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.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87708578A | 1978-02-13 | 1978-02-13 | |
| US06/078,472 US4345646A (en) | 1978-02-13 | 1979-09-24 | Apparatus for chemical cutting |
| CA000408332A CA1170163A (en) | 1982-07-29 | 1982-07-29 | Apparatus for chemical cutting |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408332A Division CA1170163A (en) | 1978-02-13 | 1982-07-29 | Apparatus for chemical cutting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1184843A true CA1184843A (en) | 1985-04-02 |
Family
ID=27167267
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000445582A Expired CA1184843A (en) | 1978-02-13 | 1984-01-18 | Apparatus for chemical cutting |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1184843A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103640042A (en) * | 2013-12-09 | 2014-03-19 | 珠海市横琴新区安泰科智能仪器有限公司 | Clamping and actuating mechanism of water jet cutter |
-
1984
- 1984-01-18 CA CA000445582A patent/CA1184843A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103640042A (en) * | 2013-12-09 | 2014-03-19 | 珠海市横琴新区安泰科智能仪器有限公司 | Clamping and actuating mechanism of water jet cutter |
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