US2616370A - Well explosive - Google Patents

Description

NOV- 4, 1952 J. FOSTER 2,616,370

WELL EXPLOSIVE Filed sept. 1o, 194e 2 SHEETS-SHEET 1 Fifg James Le w16" F05 er INVENTOR. i

BY W ATToRNEx Nov. 4, 1952 J. FOSTER 2,616,370

WELL EXPLOSIVE Filed Sept. lO, 1946 2 SHEETS--SHEET 2 .ff-i James L ewiS FOS er IN VEN TOR.

ATToY.

Patented Nov. 4, 1952 UNE'E'ED STA-TES FTENT? Fir-ECE"- This@ ,inventionj .relates gto improvements; in:

well explosives-g and.: more; jparticularly` ftogsuch explosivesA as are -used for penetrating; the'. cas-1': ing yor'wallof a well, for the purpose and as described in myA prior "patent,V No.",2,307,729, granted J anuary 5, 1943;--r

When a well is :drilled-into ia Vsubterranean formation, particularly into` the oil or 'uid' etrate the surrounding formation from the bore hole and subsequently detonating these' charges in the manner set forth* in my'prior patent, No. 2,307,729, to shatter theybase of the-'formation and cause the uid to ilow intolthe. well; The latter :has involved-the'v placing .of the explosive bymeans of a toolof substantial weightlwhich must be lowered into a hole andthen'removed.y

Such a tool is relatively heavy and expensive,

and must be removed andl serviced at additional expense before it can be re'used. While it has considerable advantage over the shooting practice in use heretofore, it has A'been said to be subject to the objections mentioned, and in some instances does not justify the'added eX- pense.

The object of this invention is ftocause a penetration -of the. surrounding subterranean. formationfrom within the bore.hole'without the-- expense.;incidentyto the l.tooL-.that projectiles of the character described, by :simplifying-the characterof the penetrating charge fand' `like-- wise the character of the tool usedtherewith, while nevertheless effectively penetrating the surrounding casing' or'wall of the well to a sufficient extent so as 'to permit the fluid `to iiow into the well and to 'produce channels and basins in the formation which will assist in the recovery oi oil or other fluid therefrom.

I have discovered that this object may be accomplished by penetrating the fluid-bearing i formation by the use of the channelling or penetrating eiect of a small charge of explosive so shaped as to focus the point of action thereof so that a relatively small area of the'wall of thewell or bore hole will be acted on atone timel by the detonating force, which will nevertheless be effective to penetrate thesteel case or the rock wall in an eiective action'directed at a point. This concentration vof force will A createA Vone `or more .T cavitiesrin the orr'nation,thus.;increasing: 60

the recovery area thereof, especially-:whenfousedf in oilwells,l thereby increasingi the.,.effective production 'of such wells.

The effective chargel may? "be produced by shapingV the rfacethereof substantially in ,the form of a' concave'lens having the focal point at'or adjacent the end ofthe charge container whereby, 1when 'presented to the` surrounding walll of the -formation'or the casing, the concentration of force at the focal point of thesur-v face will be effective -to disintegrate the wall or casing and formV a hole or cavity therein which will continue into' the formation to `an extent depending upon the effective charge of the charge container.

Certain embodiments ofA the invention are -i1v lustrated in the accompanying drawings, in which:

Fig.` 1 is a vertical sectional view through a bore hole forminga well and having a surrounding -casing therein, showing one form of tool adaptedA for'use'according to this invention; r

Fig. 2 is a similar-view showing the bottom of the bore hole `belowethecasing and illustrating a modiediormfof tool according to this.in-`

vention Fig. 3 is a longitudinal rsection through-v .a charge container-f device of the character 'used'v with the tool shownfin Fig. -2, on the'lineY 3*--3v of Fig. r4;

Fig, 4 is a top plan view thereof with va por-v tion in section and taken yon-the line 4-4 of Fig; 2;

Fig. 5 is -a cross-'section' through the .well'on the-lineE-E of Fig. 11;

Figf is :a longitudinal section-'through the` charge 1, containerY .thereof :ont vthe. line ,6--t of Fir-ir.. .5.;

Figr'] is a' v-iew'similanito Figivjlr but shows'thecharge containers retracted Figjg is a diagrammatic: View.v of the-Wiring connections `of the tool sh'own'iniiFgs.- 1, andfz to '7; r

Fig. 9 isia vertical'sectionalview' through'a cased well' showing still another form'of tool operatively Vmounted -tlrie`rein;` and Fig. l0 is a sectionalview through the charge' container used in the tool shown in Fig. 9.

The :invention is illustrated and described as" appliedl to a bore hole or well in a subterranean formation where it has special utility Vfor openingY up the formation either through the casing that surrounds the bore hole or at the bottom of the bore hole below the casing, to increase vthe-circulationof huid, particularly oil, from the surroundingformation intothe bore hole, for the purposes-:set forth more in detail in my prior patent,iNo. '2,307,729'. l As.illustrated,.the'v well isformedby drilling; a hole downwardly from the surface intotm' rounding fluid-bearing formation generally as indicated at I, which hole is shown at 2 and often has an enlarged cavity 3 at the bottom thereof. The bore hole 2 usually is lined with a steel casing 4 that extends downwardly from the surface throughout the major portion of the length of the bore hole and is shown as extending to the cavity 3. Frequently it is desired to penetrate the surrounding casing 4 particularly at a point near the bottom of the well and into the fluid-bearing formation I, and also to penetrate the surrounding Wall of the cavity 3 by tunnels or cavities of the character set forth in i my prior patent, No. 2,307,729, to provide for the flow of oil or other fluid from the surrounding formation into the well.

One form of tool for this purpose is shown generally in Figs. 1 and 7, and more in detail in Figs. 5 and 6. This tool uses a plurality of explosive devices which cooperate in an assembled relation to form a tool generally as indicated at 5 in Figs. 1 and 7. This tool 5 is suspended by a cable that is adapted to be lowered into the well from the surface of the ground for suspending the tool therein at the proper point where the surrounding wall of the well is to be penetrated. This cable S may be an electrical cable through which the wires for directing the electric current extend or it may be a suspending cable having the Wires associated therewith, whichever may be desired.

-The lower end of the cable 6 is shown as suspending thereby an eyelet 'I, to which is secured and suspended a body 8. The body 8 supports a plurality of yieldable members 9, preferably in the form of leaf springs, one end of each of which is attached t0 a side of the body 8, and the other end carries an explosive device I0.

The yieldable supports 9 normally are so formed as to position the charge containers Il] in laterally expanded relation substantially as shown in'Figs. 1 and 5, bearing axially against the inner wall of the well or the casing 4. However, provision is made for holding these in contracted relation during the lowering of the device into the well, as shown in Fig. '7. For this purpose I have provided thereon an encircling member II which extends around the yieldable supports 9, as shown in Fig. '7, at a point above the charge containers II'I.v This restraining device II may be constructed of any suitable material that has sufcient .strength to hold these yieldable supports in contracted relation and yet is l.capable of being released readily when the tool has been lowered to the desired point in the well. Thus it may be formed of a low fusion metal, or of a cord such as cotton or lfibre saturated with a combustible substance or an explosive, which will fuse or ignite sufficiently to release the yieldable supports 9. Such a releasing may be accomplished by an electric coil, shown at I2 in Fig. 8, arranged in heat exchange relation with the restraining device II, as surrounding one side thereof, and adapted to be connected with a source of electrical supply through a circuit I3. A control switch I4 may be used at the surface of the ground which, when closedI will electrically energize the coil I2 to disintegrate the restraining device I I and release the latter from its holding encirclement of the yieldable supports-9. This will permit lateral expansion of these supports to direct the outer ends of the charge containers I0 against the surrounding wall of the well or the casing 4, as shown in One form of explosive device is shown in section in Fig. 6, in which the device I is in the form of a cylindrical container closed at opposite ends but in which the closed outer end I5 is shown as concave. Fixed in the casing of the explosive device is a head I5 which forms an abutment for the explosive charge Il. This explosive charge is shown as concavo-convex with a spherically concave face I8 facing the concave end wall l5 of the casing and having a focal point substantially at or beyond the end wall as indicated at IS. Thus the lens-shaped explosive charge I'I is so formed as to focus its detonating effect substantially in the direction indicated by dotted lines in Fig. 6 toward the focal point I9 adjacent or beyond the end wall" of the casing'.

It is preferred forthe'best effect to use an explosive composition which has high speed detonation, such as TNT er nitroglycerine. However, manyother detonating explosives will produce this effect to varying degrees, such as dynamite. Such a detonating explosive appears to function by its high concentration of explosive action substantially in a conical effect, as described, which will direct its intensity substantially at the apex of the cone in a manner effectively to disintegrate steel, rockor earth formation to an extent depending upon the amount of explosive composition used until its force has been expended.

The ignition of the explosive charge may be accomplished by an electric detonator generally indicated at 2G in Figs. 6 and 8, one such heating element or detonator being provided for each charge and adapted to be connected with the electrical circuit I 3 connected in parallel with the circuit I3, but controlled by a switch 2| located at the surface of the ground. This detonator is shown as enclosed within the casing of the charge container I0, which casing is watertight when lowered into the well, and sealed at the point where the electric Wires pass through the wall casing.

In using this form of tool, the parts are lowered into the well to the desired point for penetration of the surrounding wall or the casing, substantially as illustrated in Fig. '7. When the tool reaches substantially the depth where perforation is desired, the lowering action of the cable E is suspended and then the switch I4 is closed to energize the coil I2. This disintegrates the encircling element II and allows `the natural resiliency of the spring supports 9 to expand the charge containers I6 outwardly against the wall of the well or the casing d, 'substantially asindicated in Figs. 1 'and 5.

Then upon the closing of the-switch 2| the electric detonators 2E will cause an ignition Vof the explosive charge Il in each of the charge containers. This will have the effect described above, of concentrating the explosive force of the lens-like explosive substantially at the focus thereof which is located adjacent or externally of the end wall of the charge container. With the charge container substantially in bearing relation with the surrounding wall of the well it will -be understood,that the number thereof may be increased or decreased as desired, and that these may be used either above or below the lower end of the casing in like manner.

When it is impractical to use yieldable supports that will tend to direct the charge containers against the surrounding wall of the bore hole, as for instance when a large cavity 3 is encountered therein, as indicated in Fig. 2, a similar efect may be accomplished by the form of tool shown in Figs. 2 to 4.

In this ferm is shown a plurality of vertically spaced charge containers generally designated at held in spaced relation by tubes 5I and with a tube 32 projecting upwardly therefrom to which is secured a supporting cable 33 that extends upwardly to the surface of the ground. This cable supports the tool as it is lowered to the desired point in the bore hole or the cavity 3.

Each charge container 33 is shown in Fig. 3 as formed by surrounding casing with a lens-like explosive charge 34 similar in character and effect to the charge il described above, and adapted to be ignited by an electrical detonator 35. This detonator 35 is ignited by a fuse 36 that extends therefrom into an explosive charge 31 located in a barrel 38.

The barrel 38 is mounted centrally of the charge container 39 and opens toward the rear of the latter, as shown in Fig. 3, with its end normally closed by wadding 3S. movable readily by the initial explosion of the explosive charge 31 when ignited, as by an electrical heating element i0 embedded in the end of the explosive charge 3l. The effect of thus igniting the explosive charge will be to expel the wadding 39 from the open end of the barrel 38 and then to direct a jet-like action or discharge through the open end of the barrel which will have the eiect of propelling the charge container 30 in the opposite direction against the face of the cavity 3, as indicated in Fig. 2, and continuing until the force of the explosive charge 31 is spent. This should be so proportioned as to confine the charge container against the face and until after the igniting of the fuse 36 and the action of the detonator 35 to cause combustion of the explosive mixture 34 when the action of the latter will hold the charge container in this position during its eiective operation. The electric heating element 40 may be energized through the electric wire generally indicated at 4 I.

Where several charge containers are used in an assembly substantially as shown in Fig. 2, these will function simultaneously to form holes into the formation at vertically spaced points. However, they may be turned at angles to each other if desired instead of located in the parallel relation illustrated.

It is preferable to use an extended strip or shoe, generally indicated at 42, at the end of the charge container 30, which abuts against the face of the bore hole, so as to stabilize the charge container in its bearing action against the face until the action of the shaped charge takes place. 'I'his strip 42 thus will hold the charge container against the face substantially at right angles thereto in position for elective action on the surrounding formation by the concentrated force of the burning or explosive charge shaped in the manner described.

Still another form of tool is shown in Figs. `9 and 10, in which a plurality of charge containers are shown as mounted on upwardly extending arms 5l preferably pivoted together at 52 and The latter is renormally contracted by a coiled spring 53 connected therebetween. Any desired number of these charge containers may be used, although two are shown for purpose of illustration, The arms 5I normally are held in spaced relation by a spacer 54.

The pivotal support 52 preferably is in the form of a spider suspended by a cable 55 that extends upwardly to the surface of the ground. A tool 56, shown as having a conical lower face 51, is slidably mounted freely on the cable 55 in position to be dropped downward along the cable for detonating the charge containers 58.

Accordingly each of the charge containers 59 is shown in Fig. 10 as having a percussion cap 58 arranged to detonate a shaped charge 59 in the charge container when actuated by a firing pin 6U. The shaped charge 59 preferably is of the character described above and having like effect in use.

When the tool 56 is dropped by gravity along the cable 55 the conical end thereof will enter between the charge containers 50 and `cause these to be spread outward from the full line to the dotted line position shown in Fig. 9. At the same time this tool will actuate the firing pin 60 to discharge the percussion cap 58 and cause ignition of the shaped charge 59, which will then effectively penetrate the surrounding wall, and the casing if used, of the formation.

While the invention has been described in certain embodiments, it is recognized that these are merely illustrative of various forms of the invention, and that other variations and changes may be made therein without departing from the invention, except as specified in the claim.

I claim:

A well explosive comprising a plurality of containers each having a shaped charge therein spaced from a wall thereof, resilient supports secured to said containers, means for retaining said resilient supports in retracted position, said means comprising a band extending around said resilient supports, means for causing the disintegration of said band preparatory to detonating said shaped charges, means for spreading said resilient supports outward simultaneously to bring said ends of said containers into contact with the Wall of a well, and means to detonate said shaped charges for the penetration of the wall of the well.

JAMES LEWIS FOSTER.

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

UNITED STATES PATENTS Number Name Date 615,321 Straub et al Dec. 6, 1898 1,560,815 Hill Nov. 10, 1925 1,582,184 Mims Apr. 27, 1926 2,233,930 Witty Mar. 4, 1941 2,399,211 Davis et al. Apr. 30, 1946 2,494,256 Muskat Jan. 10, 1950 FOREIGN PATENTS Number Country Date 28,030 Great Britain 1911 OTHER REFERENCES The Explosives Engineer, July-August 1945; pps. ISU-163; 102-56 (X).

Zeitschrift fur das Gesamte Schiess und Sprengstowesen, May 15, 1914, pps. 18S-187.

The Oil Weekly, July 8, 1946, pps. 56 and 58.

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