US2821921A - Well shooting unit utilizing a porous enclosing body - Google Patents

Description

Feb. 4, 1958 T. B. MARTIN Y 2,821,921

WELL SHOOTING UNIT UTILIZING A POROUS ENCLOSING BODY Original Filed Sept. 2. 1950 5 Sheets-Sheet 1 INVENTOR. Thomas B. Martin HIS ATTORNEYS 1953 T. B. MARTIN 2,821,921

WELL SHOOTING UNIT UTILIZING A POROUS ENCLOSING BdDY Original Filed Sept. 2, 1950 3 Sheets-Sheet 2 INVENTOR.

Thomas B. Mar/in H /5 ATTOR/VE Y5 T. B. MARTIN 2,821,921

WELL SHOOTING UNIT UTILIZING A POROUS ENCLOSING BODY Feb. 4, 1958 3 Sheets-Sheet 5 Original Filed Sept. 2. 1950 INVENTOR.

Thomas B. Martin w,%% HIS ATTORNEYS United States Patent-O WELL SHOOTING UNIT UTILIZING A POROUS ENCLOSING BODY Thomas B. Martin, Bradford, Pa.

Continuation of application Serial No. 183,066, Septemher 2, 1950. This application August 28, 1956, Serial No. 607,540 i quartsusing old methods.

efiectiveness of the charge is thus lost in vertical forces and in forces which tend to damage thewell hole and particularly, its supporting rock-bearingstrata. In addition, considerable cleaning out work must be accomplished in the well hole' afterthe shooting operation. Due to the lack of efi'iciency of the charge as thus employed, it is frequently necessary to enlargethe diameter of the well hole for the shooting operation, so that a charge of increased size may be introduced therein. This is an expensive and time consuming operation and the results obtained do not always warrant this expense. This type of explosive action also has another disadvantage in that it tends to drive in rock or shale and clog and compact the sand of the productive stratum.

In an endeavor to provide a more effective'action, one experimenter employed the idea of shooting a projectile into a stratum and then subsequently exploding it; another employed heavy slugs for making superficial openings in the stratum adjacent the well hole to provide an entry for a chemical treating fluid. The first mentioned, method is expensive, its effectiveness and its distance of penetration are limited, it also tends to compact the sand and the shell fragments tendto further block oflf flow pores. The second-mentionedmethod is expensive, is dangerous due to the fact that a corrosive chemical is used with an explosive, its results are superficialand depend primarily upon the corrosive chemical, and the heavy slugs tend to block off flow pores. These and other methods have definite deficiencies that limittheir utility and eifectiveness. A n

In endeavoring .to solve the problem. heretofore pre: sented in the art in question, I havekept in" mind the need for an explosive string ,ha ving aminimum weight which will be of inexpensive construction and have requisite strength for supporting explosive charges at suitable intervals along the depth of the well holecorresponding to productive strata, 'I'he presentinvention, as distinguished from the inventioii describedfin the below-mentioned copending application, deals with explosive. action.

that is more effective from. a permeabilityiincreasing standpoint within a particularstiatum.

This is a continuation of my application No. 183,066, filed September 2, 1950, now abandoned, which, in, turn, is a continuation-in-part of my application No. 778,892, entitled, Directional Shooting of Wells and filed October 9, 1947, now abandoned. In accordancefwith my present disclosure, I employ means which is effective along the full depth of the productive stratum and which has a loosening-up or permeability-increasing effect which'wis substantially uniform for the depth rot. the stratum-and 2,821,921 Eatented Feb. 4, 19 58 2 which penetrates many feet along the stratum. In this manner, a maximum increase in production of a particular stratum of a well is obtained. The forces are'also so directed as to. prevent damage to the well hole and to provide a maximum effective utilization of a particular explosive charge. As a result, I have been able to use charges of much smaller diameter than heretofore and to eliminate any need for enlarging the well hole to obtain a requisite effective shooting action. For example, one quart of explosive employed in accordance with the prin ciples of my invention will do the work of four or five In addition, only about 3% of the cleaning out ordinarily necessary after the shooting application is required. Under various condit ons l utilize 30 to 80 quarts of explosive with an average-of about 40 quarts as compared to a normal average of about 300 quarts and a range of about 250 to 350 quarts.

In view of the above it has been an object of my present invention to devise new, improved, and more eflicient procedure and apparatus for shooting wells;

Another object has been to provide an inexpensive but highly practical method of and apparatus for increasing the productive capacity of a well employing a shooting or explosive method;

A further object has been to devise an explosive con tainer having a porous liner which will be of light weight construction and which will efiectively direct the explosive forces to provide a maximum permeability-increasing effect on productive stratum; L

A still further object has been to provide a timed cleaning out action in shooting wells;

These and many other objects of my invention will appear to those skilled in the art from the illustrated embodiments thereof. 1

In the drawings:

Figure 1 is a longitudinal view in elevation of abailer type of container constructed in accordance With myinvention;

Fig. 2 is a sectional view in elevation taken along the line IIII of Figure 1;

Fig. 3 is a top plan view of the construction of Figure 1;

Fig. 4 is a horizontal section. taken along the line IVIV of Figure 2; M.

Fig. 5 is a sectional view in vertical elevation of an explosive container constructed in accordance with my invention which may be employed with the bailer type of Figure 1;

Fig. 6 is a somewhat diagrammatic vertical sectional view in elevation showing an assembly of explosive containers of the type of Figures 1 and 5 as employed in connection with the shooting of a well hole;

Fig. 7 is a fragmentary vertical section of a portion of a well hole illustrating somewhat diagrammatically the appearance of the productive and rock strata after an explosive shot has been carried out in. accordance with my invention;

Fig. 8 is a sectional view in elevation through a bottom unit that may be employed in connection with the con tainer units of Figures 1 and 5, as shown by the assembly of Figure 6; I

Fig. 9 is a diagrammatic plan view illustrating a method of utilizing a longitudinal length of a solidified explosive body to provide a plurality of severed pieces of the requisite length, as based upon the depth or thickness of a particular productive stratum;

Fig. 10 is a vertical view in elevation and partial section illustrating a further step in carrying out the procedure of Figure 9 wherein, the individual stick pieces- Fig. 11 is a vertical view in sectional elevation through a string -of .explosive "units assembled in accordance with my invention and utilizing explosive sticks, such as provided in accordance with the procedure of Figures ,9 and and Fig. 12 is a view similar to Figure 11 employing a modified construction of explosive units.

Inan endeavor to find some way by which the. distance effectiveness of an explosive charge could be increased along a productive stratum consistingof a material such as sand, I ran into the problemof doing so without substantially compacting the material. That is, Iv found that the desideratum is to not only provide a maximum extent of force action along the stratum, but to also employ such force action in a manner to increase rather than decrease the permeability of its mass relationship, all to the end that resistance to productive flow through. the stratum will be lessened and flow increased. In ad-' dition, I found that the major force action must be directed or concentrated along the stratum.

I experimented with many arrangements which ineluded the use of a solid material or of an air space bebind the explosive, a solid material or an enclosedair space in front of the explosive, back and front combinations of these, a plurality of radially-outwardly directed chambers, bullet-like slugs, etc., but found that the de'sideratum could not thus be reached. Finally. on, the basis that even small and light weight, force-driven, particles will penetrate relatively hard materials, I wasv inspired by the thought that a combination of a maximum. force-directing eflfect with a proper utilization of small, or,

structing particles or pores of the stratum, providedthat.

they are not massed, but are in a dispersed or spaeed-relationship with respect to each other in a fluid stream,

preferably gas-borne. It also appears that used inthis manner, such particles serve to open up clogged faults and;

pores in a stratum and provide an open flow path-for fluid therealong. In this manner, explosiveforce can be employed in a permeability-increasing effect rather than in a compacting effect.

I further determined that I could provide the above type of action along with a force directing and concentrating action by placing an enclosing, pre-shaped, outer body or cylinder about and along a core made up. of an.

explosive charge or mass, where the body is made up of relatively fine particles in a porous mass. An integrally sintered mass of glass and carbon particles was found to be well suited for this purpose, in that it is shaperetaining and self-supporting and provides a'large nummer of air spaces or interstices of a non-cellular type throughout its extent, as defined by relatively. hard, refractory-like particles held together as a frangible body. For. optimum results, I use a body of refractory, hard plastic, and similar materials which is frangible and will provide relatively fine, hard particles, at least when the charge is exploded.

The integral relationship of the particles, as employed, provides the requisite, fixed-positioned, air-space-to-particle relationship and force-directionating effect and also prevents massing and packing of particles which would occur if they were loosely carried.

As shown in the illustrated embodiments of my invention, the light-weight, outer, frangible and porous body 15 of hard refractory particles has, its air-spaee-defining in-Figure-6,- provide a depth alignment withaa productive stratum and directly receive therein the gases generated by the explosive material and accomplish a maximum force-directing effect by the expansion of the explosive gases within such outer body. As a result, as previously explained, the refractory particles of such outer body are gas-borneand explosive-force driven a maximum distance into and along the productive stratum. As distinguished from the employment of a solid glass body or of glass marble'projectiles, the porous body of my inventionis thus completely broken up and shattered into minute gas-borne particles during the expansion. of r the explosive gases. That is, a complete shattering action. is accomplished while the explosive gases are expanding away from the inner core and not when the material is projected or force-driven into the productive strata. This initial action is believed to be the key to the exceptional effectiveness and the increased extent'of penetration into an opening up of the productive stratum for a lateral or radial extent of'800 feet or more from the well hole.

It will be noted that in the embodiment of Figure 2, holes 18b provide direct communication between the explosive material'22 and the air space of the body 15, that in the embodiment of Figures 5 and 12, the explosive material is positioned in direct contact with the porous body, and that in the embodiment of Figure ll, cardboard 32 is employed which is itself highly porous and presents little or no resistance to explosive gas flow. Such constructions are, of course, distinguished from a construction which is employed primarily to develop a maximum downward vertical force to clean out the well hole, see for example Figure 8 of the drawings.

In employing one-embodiment of my present invention, a lightweight explosive unit has a shell-like outer, cylindrical wall'about a longitudinally (vertically)-extending,

annular layer, or body ofth'e highly porous material which will provide maximum lightness in the overall construction and will at the same time provide a localization of the explosive action substantially to the width or depth of the stratum which is to be shot and produce a maximum permeability-increasing effect thereupon. porousbody either with or without an inner, concentric, shell-like wall'defines an explosive-receiving core chamber along its longitudinal extent. Nitroglycerin which is the common explosive material employed, has in liquid form a high viscosity and very poor permeability; thus, I have .determined that it can be poured into a container and against the porous body without danger of filling its interstices and spoiling the effectiveness of the desired type ofexplosive action.

A number ofunits may be suspended and connected in a spaced apart relationship along the well hole, corresponding to thenumber o f productive strata along the depth of'such hole, by light-weight earryingmeans, such asconnector shells or tubes. Incarrying outthe operation,'the.longitudina1extents oflthe explosive core and the porous. body'are important considerations, not the actual length or depth of the container-or can. The shell walls, the connector shells, and top and both walls may be of a light, non-ferrous metal such as tin, or of glass or plastic material,

In another embodiment of my inventionl make use of solidexplosiye material (such as solidified nitroglycerin) in.the formv of a s tick or, bar. Such stick of material. is provided along its length withan outer, enclosing layer. or protective casing of paraffin-treated cardboard, of non ferrous light metal (such as tin), or some other. suitable material of atype thatisnon-spark producing. Between thisstick 0r ba11of explosive and its outer protective layer or coating, I; interposea porous bodyv layer of the type above mentioned. The; stick is setinto the field and cut up. into short lengths: by; anomferrbus saw, so that a number-of 'pieces are provided: corresponding to thedepth of individual stratumtdbe shot; Incthisconnection, nit.

The

.5 troglycerin in solid form is particularly suitable and is relatively stable when handled in this manner. Each'length may then be axially-centrally drilled or punched out, if not before provided in the stick at the explosive plant, and a cable or a smalldiameter connector tube or shell strung therethrough for suspending it as a unit of a string. Top and bottom, shell-like discs of a light weight metal such as tin, of plastic, glass, or wood having a suitable diameter are then slid over the carrying or connector cable or tube and mounted or secured with respect thereto in abutment with the topand bottom ends of the explosive unit to hold it in a proper relationship with respect to successive units along the length of the wire. Such unit assembly may be lowered into the well hole and shot. As shown in the drawings, Iprefer to provide the supporting discs with a greater diameter than the sticks, so that they can be employed to guide and centrally align the units with respect to walls of the well hole.

Also, I have provided the explosive stick or longitudinal bar as manufactured for distribution in the field with a preformed, hollow axial center and with an outer enclosing wall of the porous body material. Wire nails, wire loops, cotter pins, etc., can be used for securing connector tube ends of each unit to the connector tube ends of adjacent units or for mounting each unit on a cable. If connector tubes are used, they are preferably flexible enough, so that one may telescope within another; they also serve the additional purpose of providing a passageway for electric wires along the assembly to excite a series of unit charges and preferably, to do so simultaneously.

Since explosive charges as employed in accordance. with my present invention have little or no axial directionating efiect, I have shown a different type of unit at the bottom end of the shooting string for cleaning out debris loosened by the other units. For this purpose, a slower explosive or a later-fired explosive having an enlarged hollow core or centeris positioned at the bottom end of the string (opposite a rock bearing stratum) to direct its major explosive gas or force vertically upwardly along the well bore or hole to carry out the debris.

A Dynamite may be used, since it is about 45 seconds slower than glycerin.

In making the optimum body material, a batch of fine glass particles and carbon are heat-sintered in a vpan placed in a furnace. The carbon foams up and a hard,- porous mass is produced. Such mass may then be finally shaped by employing aC'arborundum wheel. For facilitating mounting such body, it is shown shaped into semi-circular halves which are fitted together into a cylinder. Any seepage of liquid explosive that may occur between the edges of the semi-circular halves of this body will be a minimum and will .not adversely aflect the desired results.

In assembling the units or containers of the first-mentioned type, they may be connected by light metal, spacer tubes which interfit with each other and are secured together by locking keys (wire, cotter pins, etc.) that extend through registering holes therein. When the weight of the'string is over 80 pounds, the upper or bailer unit or container may have a reinforcing inner sleeve wall or tube within its porous body. However, the subsequent cans need not have such a reinforcing tube and the explosive can be poured directly into the chamber defined by its porous body to provide a unit of exceptionally light weight, inexpensive, yet of highly efiicient force effect.

To illustrate the eifectiveness of the force action involved, l have discovered that the oil, for example, is driven back along the stratum shot, so that it sometimes takes a few days for production to start, but when it does start,.the increase in flow provided is remarkable. By actual tests I have discovered that the permeability-increasing action is effective for over 800 feet or more along the particular stratum, radially or transversely away from the well hole. 1

I find that the air-space, porous body of cylindrical form should be placed directly opposite the productive or sand stratum with its top and bottom ends in alignment with the top and bottom extent of the stratum. Under some conditions, there is an advantage in extending the explosive in depth, slightly above and below the porous body. This will provide: (1) a rounding oil of corners of slate or rock strata above and below the productive stratum, thereby facilitating cleaning out, as some of the slate has a tendency to break oil when the tools and bailer are run; (2) the use of a larger concentration of explosive where larger shots are desirable than the diameter of the well hole will permit; and (3), to some extent, help productive flow after the shot.

The charges may be detonated by magneto and electrical connections, by a go-devil, or by dropping a godevil on a magneto handle where the magneto is' suspended in the well hole.

In the embodiment of my invention illustrated in Figures 1 to 6 inclusive, I find it advantageous to employ an uppermost or top container unit 10 of the bailer type of. Figure 1 and subsequent units 10 of the type of Figure 5. With reference to Figures 1, 2 and 3, the bailer type. of unit has a cylindrical, longitudinally-axially-extending outer shell wall 11 which at its upper end receives and is secured to a funnel or frusto-conical-shaped, pouring shell wall 12. A pair of ear lugs 13 is riveted or secured on opposite sides of the shell 12 to extend upwardly therefrom and receive a bailer wire handle 14. As shown particularly in Figure 6, the container unit 10 may be suspended from a cable 31 by means of its bailer handle 14.

A concentric, longitudinally-axially-extending inner tube or shell wall 18 is positioned to extend in a spaced relation along the shell walls 11 and 12 and out of or beyond their respective top and bottom ends. The inner and outer shell walls 11 and 18 define a space or chamber for receiving the shaped, air-space-defining, porous body 15. The body 15 of the inner shell wall 18 internally defines a core chamber for receiving liquid explosive material 22 such as nitroglycerin. A bottom closure disc ring or shell wall portion 17 has an outer angle edge which interfits; with and is secured to an internal rim projection adjacent: the bottom end of the outer shell wall 11 and extends; therefrom into abutment with the inner shell wall 18 toclose off the chamber therebetween and support the lower. end of the porous body 15. An upper closure disc ring; or shell wall portion 16 may be secured to extend radially inwardly from the outer shell wall 11 to position the: upper end of the body 15. A second bottom closure disc: or shell wall portion 19 is secured to extend across the:

inner shell wall 18 to provide a bottom closure for the core chamber. It will be noted that the shell wall portion or disc 19 is spaced downwardly with respect to the bottonr end of the body 15 in such a manner as to define an extension or the core chamber which receives the explosive material 22. When, as shown in Figure 2, the explosive material 22 is filled up slightly beyond the upper end of the body 15 and extends slightly below its lower end, a rounding off of the corners of the shale or rock strata A A may be efiected simultaneously with the shooting'of the productive stratum B see Figure 7.

The outer cylindrical shell wall or tube 11 is shown reinforced at its lower end by a downwardly-converging, cone-shaped shell wall member 20 which is secured, both to the former and to the inner shell wall or tube 18. A. limit or stop annulus 21 is shown positioned to extendl about the lower end portion of the inner shell wall 18;;-

and, transversely aligned holes 18a are shown cut trans-- versely through spaced portions of the shell wall 18 which:v

. are located below the ring 21 to receive locking keys, cot-- ter pins, nails, or wires 29, see Figures 2 and 6.

As will be apparent from Figure 2, the explosive ma terial 22 may be poured into the container unit 10 along the upper funnel wall 12, through slotted openings 12a:

in eam and threugh 9 9 in h itt tube .18 fofillthfe" expissrvecare chamber. As illustrated in thi's 'figiir effthe'explosive material may be poured to a dpthslightly above the iipper edges of the body 15 t pif'ovide' thetypeof action described in connection with the spacing of the bottom closuredisc 1 9 and as illustrated ll'i Figure; 7. i

' The containers 10 and It) may be made of tin with soldered connections s or of any suitable plastic material in-.

eluding glass. As shown in Figure 6, if the inner shell wall Iortube 18 and the parts 12, 13 and 14 are of a conducting materialsuch as metal, one of the two electrical lead wires may be'eliminated in shooting an electrical cap 23. The cap 23, as shown in Figure 2, may be mounted on the inner wall of the tube 18 to extend into the explosive material 22. i

"'Ih the type of unit illustrated particularly in Figure 5, in order to avoid repetition of descriptive material, I have applied the same numerals as used in the type of Figure 2, where the parts are of similar construction. The prim cipal difference in this container from that previously de scribed, is that its inner shell wall or tube member 18 extends a short distance through the lower end of the conicshap 'ed shell or funnel member 12 and into the outer shell wall 11, .and has transversely aligned, longitudinally spaced-apart, and radially staggered hole sets 18'11, which may be aligned with the holes 18a of the tube 18 to "c'onnect or suspend the unit It) from the unit 10. Also, in this type of unit, the explosive material 22 is poured directly into the inner space defined by the bore of the body 15. Although a tube of the type of 18 may. be used, this is a simplified construction to that of the upper unit 10, since the upper unit is reinforced in view of its carrying function.

A bottom closure shell wall or disc 25 has turned-in, outer edges which interfit with an inwardly offset ring in the outer shell wall 11' to reinforce its secured relationship therewithin. The closure disc 25 is made up of an annular, upwardly offset outer portion 25:: and a circular, downwardly-offset, inner portion 25b to provide a desired spaced relationship between the bottom of the explosive material 22 and the bottom of the body 15. A shell wall of connector tube section or member 27 is secured to extend from a bottom, cone-shaped, shell wall, reinforcing or nose member 26 which, unlike the nose or cone member of the embodiment of Figure 2, may be closed off at its apex. The connecting tube member 2'7 has transversely-aligned, longitudinally spaced, and radially staggered locking key or pin-receiving holes 27a for connectmg it to an upper connector 18 of the next adjacent unit 10'.

Although I may utilize container units such as 10 and 10 along the full. length of a well hole, I also have employed a lower, cleaning out unit 40, see Figures 6 and 8. This type of unit is not employed to shoot the productive strato but to clean out the well hole of debris loosened by the strata-aligned explosive units. To best accomplish this result, the unit 40 is designed to exert a longitudinal, axial shooting force and to explode after and preferably with a lesser intensity than the explosive charges of the strata shooting units. Dynamite which is slower burning than nitroglycerin can be used in this connection. The unit 40 has an outer cylindrical shell wall 41, an interfitting bottom shell wall or closure 42, and bottom runners or restpieces 43. An inner tube or shell wall 44 is secured to the bottom wall 42 to extend upwardly in a spaced relation along the length of the outer wall 41 in a concentric relationship with respect thereto. The tubular inner and outer Walls 41 and 44 thus define an explosive receiving space between them, and the inner wall 44 defines an air space within it. Such air space directs the explosive gases vertically upwardly along the well hole in the. desired manner. After the unit or containerdt) has been filled with explosive material 45, aclosurecap-orjtop' shell well member 46 may be secured thereover by nut 31 9 1391! ass mblies 4 The memb r 46 h s aconnectortu s 9 l l1 wa s ction 48 s e to x e pwardly therefrom and is adapted to be connected, as shown in Figure 6, to a bottom connector 27 of the next preceding container unit 10'. For this purpose, the connector tube 48 has key-receiving slots or holes 38a that correspond to the previously-described slots or holes 27a of the unit 10'.

In accordance. with the other embodiment of my invention, a longitudinal. length of solidified explosive material C, such as nitroglycerin, may be used, see Figures 9 and 10. The body 15 may be assembled about the length of the length C in the manufacturing plant or may be added later as previously pointed out. As shown in Figure 9, the length C is severed in the field by a non-ferrous shear 52 into sticks or pieces of requisite length D, D1, D2, D3, etc., corresponding to the thickness or depth of the particular productive stratum B1, B2, etc., which is to be shot. The severed sticks or pieces are collected on a frame 53 and then are provided with an axial hole through their center by punch mechanism 56, 57, see Figure 10.

In Figurell, I have illustrated explosive units employing severed sticks such as D, D1, etc., which in this figure have been renumbered as 30. Each explosive piece orstick 30 is positioned by top and bottom shell walls or discs 34 and 34' of metal, plastic, or other suitable material. Locking keys, pins, or loops 35 and 35' cooperate with the carrying cable 31 and these discs to position the explosive units in a desired relationship along the cable 31, If the explosivelengths C are shipped from the factory without the body 15 thereabout, they may be provided with a paraffin-treated cardboard cover 32 and then pieces of the body material 15 severed and placed thereover and clamped thereto by wire or strap bands 33. In this Figure 1.1, I have shown aslightly modified type of bottom explosive unit 40, the construction of which is the same as the unit of Figure 8, except that its top closure member 46' has no connector 48, but has a hole through its center to receive a locking loop or key 31a to secure the lower end of the cable 31 thereto.

In Figure 12, I have shown a slightly modified arrangement utilizing a unitary piece of solidified explosive material 30 and body material 15 which are provided with a cardboard cover or enclosure, 37'. The assembly is severed as a unit into the desired requisitepieces. The center hole through each piece may be made large enough to receive a small diameter carrying or connector tube 36. This tube 36 should be as small aspossible to permit the cable 31 to thread therethrough. In this embodiment, I have shown a modified type of support shell wall or disc member 38 which has turned-down guide, runner edges 38a. Itwill be noted in both the embodiments of Figures 11 and 12, that the support shell wall or disc members 34, 34' and 38 may extend radially-outwardly beyond the explosive unit to guide suchv unit and concentricallyalign it within the well bore. The runner 38a of the embodiment of Figure 12 aids in such action and reinforces the positioninginember or bottom support disc 38. In this embodiment, I do not show upper positioning shell wall members or discs for the explosive units and secure each unit in position in a spaced relationship along thev carrier tube 36 by: keys or looking pieces 39 which extend therethrough.

The lower orclean-out explosive unit 40 of the arrangement of, Figure 12 is of a slightly modified type. It has an outershell' wall 41" secured to extend upwardly from a bottom shell wallor disc cap 42". An inner, concentric shell wall. or tube 44'is also secured to extend upwardly from the-bottom wall 42" to define an air space therein and to also define an explosive-receiving space with the. outer wall 41 The upper end of the tube- 44" converges to fit over the connector tube 36 and has a'set-of;transverselyealigned holes- 44"atherethrough to receive a locking key 39. The top shell wall or discclosure 46" fits about tube 44 and is secured to the side wall 41" by bolt and nut assemblies 47. The inner tube or wall 44 also serves to direct the explosive force vertically-upwardly along the wall hole.

What I claim is:

1. An improved explosive unit of the character shown and described to be lowered into a well hole in substantially vertical alignment with a productive stratum for shooting it a maximum distance laterally in a permeability-increasing manner which comprises, a verticallyextending inner core body of explosive material; an outer, vertically-extending, shape-retaining, force-directing, lightweight, frangible and porous body of hard refractory particles of heat-sintered glass and carbon in a connected and air-space defining relationship; said outer body being positioned about and substantially along the full vertical extent of said inner core body and having its defined airspace directly interposed about the core of explosive material for depth alignment with the productive stratum to be shot to directly receive therein gases generated by the explosive material and provide a maximum forcedirecting efiect and expansion of the gases within said outer body, so that the refractory particles of said outer body will be gas-borne and explosive-force-driven laterally into and for a maximum distance along the productive stratum, a tubing member extending vertically along said inner body and upwardly and downwardly therebeyond, said tubing member having open portions therethrough defining passages between said inner and outer bodies, a pouring funnel for the explosive material mounted on an upper end portion of the unit and projecting upwardly along an upper extending end portion of said tubing member, an outer casing along said outer body, said funnel having a diverging upper open mouth portion of substantially greater outer diameter than the diameter of said unit and having a converging lower end portion secured to said outer casing and open to said outer body, a bottom disk projecting radially across said inner and outer bodies and secured to said tubing member and cooperating with said outer casing to support lower end portions of said bodies, and a cone-shaped nose having a diverging portion secured to said disk member and converging downwardly along said tubing member and having a lower converging end portion secured on said tubing member.

2. An improved explosive unit of the character shown and described to be lowered into a well hole in substantially vertical alignment with a productive stratum for shooting it a maximum distance laterally in a permeabilityincreasing manner which comprises, a vertically-extending inner core body of explosive material; an outer, vertically-extending, shape-retaining, force-directing, light-weight, frangible and hard porous body of hard refractory particles in a sintered-connected and air-space defining relationship; said outer body having a pair of semi-circular halves that are fitted together to define an enclosing cylinder and being positioned laterally about and substantially along the full vertical extent of said inner core body and having its defined air-space directly interposed about the core of explosive material for depth alignment with the productive stratum to be shot in a minimized gas-flowresistance relationship with respect to the explosive material of said inner core body to directly receive therein gases generated by the explosive material and provide a maximum force-directing effect and expansion of the gases within said outer body, so that the refractory particles of said outer body will be gas-borne and explosive-forcedriven laterally into and for a maximum distance along the productive stratum, means positioning and supporting said inner and outer bodies in a vertically aligned assembled unit relationship with each other including means to suspend the assembled unit within the well hole with its vertical axis in substantial alignment with the vertical depth of the productive stratum, said last-mentioned means comprising, an inner tubing having a diameter substantially corresponding to an outer diameter of said inner body, said inner tubing having an upper portion projecting vertically above the unit and having means for connecting it to a vertically suspended upper tubing end, said inner tubing having a lower portion projecting vertically downwardly from the unit and having means for connecting it to an upper end of a lower tubing, a cone-shaped funnel portion mounted on an upper end of the unit about said upper tubing portion to project radially-outwardly from the vertical axis thereof and beyond an outer diameter of said outer body, an outer casing connected at an upper end about a downwardly-com verging periphery of said funnel portion and projecting downwardly along said outer body, at least one passageway from said funnel to said inner body, a cone-shaped nose that converges downwardly toward the vertical axis of the unit and has a maximum diameter portion corresponding substantially to the outer diameter of said casing and that is secured to a lower end of said outer casing, and said nose being secured to said lower tubing portion to project downwardly to guide the unit when it is lowered into a well hole.

3. An improved explosive unit of the character shown and described, to be lowered into a well hole in substantial vertical alignment with a productive stratum for shooting it which comprises, a vertically-extending inner tubing member to carry a body of explosive material in an aligned position therein, a vertically-extending outer tubing member of greater diameter than said inner tubing member and positioned thereabout to carry a force-directing body therein, a vertically-extending, shape-retaining, force-directing, light-weight, frangible and hard porous outer body of hard refractory particles in a sintered-connected and air-space-defining relationship, said porous outer body being positioned between said inner and outer tubing members for depth alignment with the productive stratum to be shot in a minimized gas-flow-resistance relationship with respect to the explosive material of said inner tubing member to directly receive therein gases generated by the the explosive material and provide a maximum force-directing effect and expansion of the gases therewithin, so that the refractory particles of said porous outer body will be gas-borne and explosive-force-driven laterally into and for a maximum distance along the productive stratum, said porous outer body being shaped into sectioned pieces that fit together about said inner tubing member to define an enclosing cylinder thereabout, a pouring tunnel for the explosive material mounted on an upper end portion of said outer tubing member and projecting upwardly about an upper end portion of said inner tubing member, said funnel diverging radially-outwardly beyond an outer diameter of said outer tubing member, at least one passageway from said funnel to said inner tubing member, a cone-shaped nose having its upper end portion secured to extend downwardlly from said outer tubing member, said nose converging downwardly upon and being secured to said inner tubing member, and a closure disk projecting radially across said inner to said outer tubing member and secured to said members to support their respective contents.

References Cited in the file of this patent UNITED STATES PATENTS 1,382,395 Stoops June 21, 1921 2,416,077 Yuster Feb. 18, 1947 2,671,400 Duesing Mar. 9, 1954

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