US3026939A - Explosive-actuated well tool anchor - Google Patents

Description

March 27, 1962 w. G. swEETMAN ExPLOsIvE-ACTUATED WELL TOOL ANCHOR 2 Sheets-Sheet l Filed July 50, 1959 E W//cm (i fweeman ...VQMH fw C mi:

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INVENTOR.

ATTANEV March 27, 1962 w. G. SWEETMAN 3,026,939

EXPLOSIVE-ACTUATED WELL TOOL ANCHOR Filed July 30, 1959 2 Sheets-Sheet 2 nited @rates arent l 3,026,939 Patented Mar. 27, 1962 tice 3,026,939 EXPLSIVE-ACTUATED WELL T001. ANCHOR William G. Sweetman, McCullough Tool C0., PA). Box 2575, Houston, Tex.

Filed .llnly 30, 1959, Ser. No. 830,665 Claims. (Cl. 166-55) This invention relates to improvements in anchors for well tools and more particularly to explosive-actuated anchors.

Devices for anchoring tools in well casings or other well pipes are actuated in various ways. Some employ mechanical means, such as screw-actuated or weight-responsive wedges acting on wall gripping slips. Others employ hydraulic actuating means, and still others have employed anchoring apparatus which are actuated by the force of an explosive charge to set them in the well wall.

' In the operation of various types of well tools, particularly well perforators and chemical cutting tools, such as those described in my co-pending applications Serial No. 507,316, filed May 5, 1955, now Patent No. 2,918,125, and Serial No. 735,875, filed May 16, 1958, it is of the utmost importance that the tool be positively and firmly anchored against any vertical movement during performance of the cutting or perforating function of the tool. Chemical and explosive perforating or cutting necessarily produce strong reactive forces against the tool which tend to displace the tool longitudinally of the well bore unless it is solidly anchored. uAny such longitudinal displacement of the tool, particularly during chemical cutting and perforating will result in improper cuts and ineffective perforation and, therefore, must be avoided to the greatest extent possible.

l in my aforementioned co-pending applications, I have disclosed different arrangements by which a charge of an explosive is employed to actuate the wall-engaging anchors and to also actuate the chemical charge which effects the desired cutting and perforating action. These earlier arrangements have proven entirely successful but cases have occurred when even these anchoring arrangements have not anchored the tools as solidly as necessary for accomplishing the most eiiicient cutting and perforation.

The present invention, therefore, has for its primary object the provision of an improved form of explosiveactuated anchor which obviates the diiiiculties encountered -with the earlier forms of such anchors.

An important object is the provision of an explosiveactuated anchor mechanism for well tools wherein the explosive forces are concurrently employed to 'actuate both the anchor mechanism and the well tools.

An additional object is the provision of an anchor mechanism for chemical well cutting tools wherein high pressure gases generated by the ignition of explosive material is employed to actuate and set the anchor mechanism, a portion of said gases being concurrently employed to actuate the cutting tool.

In accordance with the present invention, an arrangement is provided wherein two separate charges of eX- plosive are disposed in chambers positioned above and below the anchoring elements. Passageways provide communication between the chambers and the tool section carrying radially projectible anchor elements. A choke passage is provided in the lower end of the lower chamber. With this arrangement, the explosive charge in the upper chamber, when set oli by a suitable initiator, will generate high pressure gases which will actuate the anchor elements and will also set oti the explosive charge in the lower chamber. The gases generated in the latter will, by reason of the restriction provided by the choke passage at its lower end, supplement the expansive force of the gases generated by the rst explosive charge to intensify the projecting force on the anchor elements, to thereby assure solid anchoring of the tool to the Well wall. Hot gases leaving the lower chamber may then be applied to setting-off the perforating or cutting charges, whether of the chemical character described in the aforementioned applications, or of explosive form commonly used in bullet or shaped-charge perforators.

The pressurizing medium employed in actuating the anchor elements will be gases generated by the ignition of one of the various types of relatively slow-burning gun powders, or other deflagrating types of explosives, examples of which are black powders such as used in sporting ammunition, rocket propellant powders and the like. By appropriate selection of the explosive and by means of preparation procedures well known to those skilled in the art of such explosives, the ignition and burning rates may be eitectively controlled to generate gases at any desired rate and volume suitable for apply ing the desired pressurizing forces both to the anchor elements and to the bodies of chemical uids in the case of chemical cutters, or to other well tools which are actuatable by such pressurizing gases. The gases so generated will, of course, be at high temperature, and their pressure and temperature will be utilized to set oit bullet propellant charges or shaped-charges which may be employed in gun perforators, cutting devices, and the like, attached to the anchor sections of the tool. These gases may also be employed to actuate other types of well tools such as bridging plugs such as those disclosed in U.S. Patents 2,621,744, 2,651,371 and 2,656,891.

Various other and more specific objects and advantages of this invention will become readily apparent from the following detailed description when read in conjunction with the accompanying drawing.

In the drawing:

FIG. 1 is a generally diagrammatic view, partly in section, showing a chemical cutting tool employing an anchoring apparatus in accordance with this invention installed in a well;

FIGS. 2A, 2B and 2C, together, constitute a longitudinal sectional View of the anchoring section of the tool, taken generally along line 2 2 of FIG. 1, showing the structural details thereof; and

FIG. 3 is a cross-sectional View taken along line 3 3 of FIG. 2B.

Referring first to FIG. 1, there is shown a cutting tool, designated generally by the numeral 1, which is inserted in a string of tubing or other pipe 2, extending into a well bore B, which may be lined with the usual metal casing 3. The cutting tool comprises, in downwardly arranged succession, an upper pressurizing section, designated generally by the numeral 4, an anchor sub, designated generally by the numeral 5, a lower pressurizing section, designated generally by the numeral 6, a chemical container section, designated generally by the numeral 7, an igniter section designated generally by the numeral 3, and a discharge head section, designated generally by the numeral 9. These several sections, which are constructed of suitable strong metal, such as steel, are generally cylindrical and connected together in end-to-end co-axial relation to form an elongate cylindrical tool of substantially uniform external diameter, which is adapted for insertion into the tubing string. A tiring head section, designated generally by the numeral 10, is connected to the upper end of the tool and is suitably secured to a rope socket 11 of generally conventional form, which connects the upper end of the tool to a conventional iiexible cable 12 which is employed for lowering and raising the tool in the well bore B. The cable 12 may include electrical leads 13 for transmitting electric current from a suitable source (not shown) at 3 the surface to the interior of the tool for purposes to be subsequently described.

The details of the portions of the chemical cutting tool underlying lower pressurizing section 6 do not, of themselves, form a part of the present invention and will be referred to hereinafter only in a general way in order to illustrate the relation of the anchor elements of the tool to the cutting tool.

Referring now FIGS. 2A, 2B, 2C and 3, inclusive, which illustrate the details of the explosive-actuated anchor elements of the tool, tiring head section 10 (FIG. 2A) includes an electrically-fired, explosive initiator cap 14 of'known form mounted in a barrel 15. It will be understood that the cap 14 will be suitably connected to electrical leads 13. The cap, its supporting structure, and its connection to the leads 13 comprise conventional and well-known devices and their details likewise do not form a part of the present invention.

Upper pressurizing section 4 (FIGS. 2A and 2B) comprises a tubular metallic body having an axial bore 17 extending entirely therethrough. The upper portion of bore 17 is adapted to receive barrel 15 and cap 14 when head section 10 is made up with body 16. Bore 17, at a point somewhat below its upper end, is internally threaded at 18 to receive a choke plug 19 provided with an axial choke passage 20 registering with the bore of barrel \15 and providing communication with the lower portion of bore 17, which is herein sometimes referred to as the upper pressurizing chamber. Choke plug 19 is counterbored from its lower end to form a valve chamber 21 containing a ball check valve 22 adapted to engage a seat 23 in the upper end of chamber 21 to close oil choke passage 20 against back-flow of pressure iiuid through the choke passage. The lower end of chamber 21 is internally threaded at`24 to receive a choke bushing 25 having an axial passage 26 therethrough. 'I'he inner end of bushing 25 is provided with an upwardly extending spider 27 which serves as a lower stop for ball check valve 22 to allow the latter to move downwardly to its open position below seat 23, while per-mitting ilow of gases through the spider into passage 26. The lower end of body 16 is provided with an externally threaded pin 28 (FIG. 2B) adapted to be received in an internally threaded socket 29 formed in the upper portion of anchor sub 5.

Anchor sub 5 (FIG. 2B) comprises a generally cylindrical body 30 having a plurality of longitudinal passages 31 (three shown, see FIG. 3) of relatively restricted diameter extending entirely therethrough and laterally offset from the longitudinal axis thereof, the upper ends of passages 31 communicating with the interior of socket 29 and thence with the interior of bore 17 in the pressurizing section. The lower ends of passages 31 communicate with the interior of an internally threaded socket 32 formed at the lower end of body 30 and adapted for connection to the succeeding sections of the tool.

'Body 30 is provided with a plurality of radially disposed, angularly spaced cylinders 33, each communicating at its inner end with one of the passages 31 and at its outer end with the exterior of body 30. The outer ends of cylinders 33 are annularly enlarged to form seats 34 to receive slip elements 35 having toothed outer faces 36 adapted to grippingly engage the surrounding pipe wall when urged outwardly of body 30 against the pipe wall. Slip elements are mounted on the outer ends of cylindrical Shanks 37 which are slidably disposed in cylinders 33 and fitted with circumferentially arranged seal rings 3S, such as conventional O-rings, whereby to for-m fluid-tight slidable seals between shanks 37 and cylinders 33`l Spring retainers 39 are mounted on the exterior of body 30 to resiliently hold the slip elements in place in cylinders 33 while permitting limited outward movement thereof.

Lowerpressurizing section 6 (FIGS. 2B and 2C) comprises a tubular body 40 having an axial bore 4ltherethrough, what is sometimes hereinafter called the lower pressurizing chamber, communicating at its opposite ends with upper and lower externally threaded pin members 42 and 43, respectively. Upper pin member 42 is threadedly receivable in socket 32 at the lower end of body 30 and pin member 43 is receivable in a socket 44 provided in the upper end of chemical container section 7.

At its lower end bore 41 is internally threaded at 45 to receive an externally threaded choke plug 46 having an axial choke passage 47 extending therethrough, providing communication between bore 41 and the interior of socket 44. The bore of the latter, for purposes of illustration, is shown to be closed at its lower end by means of a shear disk D held in place against the bottom of socket 44 by a tubular retainer bushing 48 which is screwed into socket 44 into clamping engagement with the shear disk. While this arrangement is employed where chemical cutting tools are connected to the anchor elements, it will be understood that chemical container section 7 and the other elements connected to the lower end thereof may be replaced by bullet or shaped-charge perforators, or expansible plugs or the like, in which case, firing passages in the latter will be in open communication with the discharge from choke passage 47.

Disposed in upper and lower pressurizing chambers 17 and 41 are bodies of a suitable pressurizing medium (FIGS. 2A to 2C). 'I'he pressurizing medium is preferably the same in each instance and comprises a body of a relatively slow-burning or deagrating explosive material 50 of the character previously described. The body of the explosive may be in molded cylindrical form, slightly smaller in diameter than the bores of chambers 17 and 41 to allow free passage of gases about the explosive body. The latter may also be supported by tubular spacer members 511 disposed longitudinally in cham- Ibers 17 and 41. Spacer 51 in chamber 17 has one end resting on the bottom of socket 29 and supporting the body of explosive 50 on its upper end. Spacer member 51 in chamber 41 has its lower end resting on the inner end of choke plug 46 and likewise supporting its body of explosive 50 on its upper end. Spacer members 51 serve to hold the explosive bodies away from the bottom of the respective chambers, and are provided with a plurality of openings 52 in the wall thereof to permit free passage of gases formed by burning of the explosive bodies 50 `from the respective chambers into passages 31 and choke passage 47, respectively. A small pellet of an igniter explosive 53 may be positioned on the upper end of each of bodies 5t) to accelerate the burning of the latter.

The above-described device is operated in the following manner: Chambers 17 and 41 of the device will be charged with the bodies of explosive material 56 and the upper and lower pressurizing sections will be assembled with anchor sub 5. In the case of a chemical cutter these portions of the apparatus will be assembled with chemical container section 7, along with the several tool portions connected below the latter, the parts being assembled in the arrangement schematically illustrated in FIG. l. The upper end of the tool will be connected to firing head 10 and to rope socket 11. The structure will then be lowered into the tubing to the point at which it is to be operated.

Electric current, from any suitable and conventional source (not shown) will then be applied to leads 13 to set off cap 14. Flame resulting from ignition of the cap will be discharged through choke passages 20 and 26 into upper chamber 17 where it will cause successive ignition of pellet 53 and explosive material 50. The gases generated by the burning of explosive material 50 in upper chamber 17 will flow through passages 31 and exert pressure against the inner ends of shanks 37 of the slip members sutiicient to drive slips 35 outwardly into anchoring engagement with the wall of tubing 2. The pressurizing gas ilowing through passages 31 will enter the top of lower pressurizing chamber 41 and will then cause successive ignition of pellet 53 and body 50 contained in this chamber. The additional gases thus generated in the lower chamber will, by reason of the restriction formed by choke passage 47, supplement the pressure supplied from the upper pressurizing chamber to increase the driving force on slip members 35, thereby assuring application of suicient pressure to the slips to securely and solidly anchor the tool to the pipe. Gases escaping through choke passage 47 will be operative to actate the cutting and perforating elements of the tool as described in my aforementioned applications. This anchoring action will occur in advance of the discharge of the chemical fluids from the tool, or tiring of the explosive perforating or plug-expanding charges, as the case may be, so that the tool will be held rmly against movement, and particularly against upward thrust, resulting from the recoil or retractive action occurring in portions of the tool below the anchoring elements. So long as pressurizing lgases continue to discharge from chamber 41, the slips will remain anchored to the pipe. As soon as explosive material 50 has been consumed, or the internal pressure against the slips has been fully dissipated, retainer springs 39 will act on the outer end faces of slips 35 to urge them back into seats 34 and release the tool from the pipe so that it may be withdrawn from the well.

It will be understood that the internal pressure developed in upper chamber 17 will tact upon ball check valve 22 to move it to its closed position on seat 23 and thereby act to prevent loss of pressure through the upper end of the chamber.

By way of example, a chemical cutting tool of the general character illustrated, which was employed for severing two-inch well tubing, employed for i-ts anchoring elements upper and lower pressurizing sections and an anchor sub of the form and arrangement illustrated and described herein. Each of the bodies of explosive 50 consisted of 500 grains of a conventional rocket propellant powder molded into a cylindrical stick 37A@ inches in length and inch in diameter. Igniter pellets 53 consisted of grains of a conventional readily ignitable powder formed into a cylindrical wafer 1/2 inch in diameter and 1A inch long. The pressures developed -against the slips were of the order of several thousand pounds per square inch.

lFrom the `foregoing it will be seen that this invention provides la highly eicient and positive anchor means for effectively anchoring various types of well tools against any movement in the well during operation of such tools.

AIt will be understood that various changes and modifications may be made in the details of the illustrative embodiment within the scope of the appended claims without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. An explosive-actuated anchor for well tools, comprising, a body attachable to a well tool to be anchored in a well, said body having longitudinally spaced upper and lower chambers and an -anchor section between said chambers, passageways extending through said anchor section providing communication between said chambers, a flow-restricting passage defining the outlet `from said lower cham-ber, separate bodies of explosive material in each of said chambers, means for igniting the explosive material in the upper one of said chambers whereby to generate high pressure -gases which ow through said passageways and cause ignition of the explosive materia-l in the lower chamber to thereby generate additional high pressure gases, said how-restricting passage being operable to maintain high pressure of said gases in said passageways, and anchor means carrying wall-engaging elements mounted in said anchor section for projection therefrom into anchoring engagement with the well wall in response to the pressure of said gases in said passageways.

2. An explosive-actuated anchor for well tools according to claim -1 wherein said explosive material is a deagrating-type explosive.

3. An explosive-actuated anchor for Well tools according to claim 1 wherein said anchor means includes a plurality of radially disposed cylinders communicating at their inner ends with said passageways and extending to the exterior of the anchor section, and wall-gripping anchor elements slidable in said cylinders.

4. An explosive-actuated anchor for well tools according @to claim 1 wherein said upper chamber is provided with an inlet pass-age communicating with its upper end, and inwardly-opening check valve means controlling said inlet passage.

5. In combination with 'a well `tool actuatable by high iiuid pressure, an explosive-actuated anchor for said tool, comprising, -a body connectible to said tool and insertable therewith into a well, said body having longitudinally spaced upper and lower chambers and an anchor section between said chambers, passageways extending through said anchor section providing communication between said chambers, a dow-restricting passage dehning the outlet from said lower chamber into said well tool, separate bodies of explosive material in each of said chambers, means for igniting the explosive material in the upper one of said chambers whereby to generate high pressure gases which iiow through said passageways and cause ignition of the explosive material in the lower chamber to thereby generate additional high pressure gases for supplementing the pressure of the rst-generated gases, a portion of said gases being concurrently discharged through said outlet to actuate said well tool, `and anchor means mounted in said anchor section for projection therefrom into anchoring engagement with the well wall in response to the pressure of said gases in said passageways.

6. The combination of claim 5 wherein said well tool is a cutting tool employing an incendiary chemical cutting agent.

7. The combination of claim 5 wherein said well tool is a perforator.

8. The combination of claim 5 wherein said explosive material is a deagrating-type explosive.

9. The combination of claim 5 wherein said anchor means includes a plurality of radially disposed cylinders communicating at their inner ends with said passageways and extending to the exterior of the anchor section, and wall-gripping anchor elements slidable in said cylinders.

10. The combination of claim 5 wherein the upper chamber is provided with an inlet passage communicating with its upper end, and inwardly-opening check valve means controlling said inlet passage.

References. Cited, in. the le o this. patent UNITED srAfrEs PATENTS

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