US3327793A

US3327793A - Multiple-shot bullet gun for perforating well casing

Info

Publication number: US3327793A
Application number: US412487A
Authority: US
Inventors: Forrest V Porter
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1964-11-19
Filing date: 1964-11-19
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27

Description

June 27, 1967 F. v. PORTER 3,327,793

MULTIPLE-SHOT BULLET GUN FOR PERFORATING WELL CASING Filed Nov. 19, 1964 l 24 k; 80lg 72 -E- 78 78 79 FIG. 1 Mam INVENTOR.

FORREST V. PORTER 25 BY gum X14 44 .ATTORNEY United States Patent 3,327,793 MULTIPLE-SHOT BULLET GUN FOR PERFORATING WELL CASING Forrest V. Porter, Houston, Tex., assignor to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware Filed Nov. 19, 1964, Ser. No. 412,487 8 Claims. (Cl. 1754.55)

This invention relates to well perforating and more particularly to a multiple-shot bullet gun for perforating well casing.

It is common practice in completing oil and gas wells to line the borehole with a steel casing. In order to start the flow of fluid into the well, the casing is perforated. Either bullets fired from a well perforating gun or jets resulting from shaped charges are customarily used for perforating the casing. The present invention relates to an improved bullet perforating gun.

Bullet perforating guns normally have a plurality of individual gun units, customarily twenty-five or more, which may be fired either more or less simultaneously or selectively. The body of a bullet perforating gun has generally been a unitary member and since it contains twentyfive or more individual gun units is quite long. While it is common practice to use replaceable gun barrels to extend the life of the bullet perforating gun, occasionally conditions will develop which will result in an explosion rupturing the gun body, consequently requiring replacement of the entire gun body. Accordingly, it is an object of the present invention to provide an improved bullet perforating gun comprised of a plurality of individual gun sections which are detachably secured together to form a composite bullet perforating gun.

Having a composite bullet perforating gun formed of a plurality of individual gun sections has several advantages over a multiple-shot bullet perforating gun having a unitary body. As mentioned, occasionally there are explosions which rupture the gun body. If the bullet perforating gun is formed of individual gun sections such an explosion will only destroy the particular gun section in which the explosion takes place and removal and replacement of such section will restore the gun. This feature results in a considerable saving since the cost of replacing a twenty-five shot gun body is considerable. Further, the bar stock steel, which is the material used for gun bodies, will invariably contain some defects and although great pains are taken to discover such defects, nevertheless, occasionally such defect will be undetected. Again it is less expensive to replace a single gun section than an entire multiple-shot gun body. Another advantage which results from utilizing individual gun sections rather than having a unitary gun body is that individual gun sections are more susceptible to at least semi-quantity manufacturing techniques with the resulting lower cost and lesser reject cost. Accordingly, it is another object to provide a multipleshot bullet perforating gun formed of a plurality of individual gun sections which are so designed that they may be produced on a semi mass production basis.

One further advantage of having individual gun units results from the fact that one of the difiicult aspects in manufacturing bodies for perforating guns is the heat treating of the body. Since the effective barrel length of a bullet perforating gun is very short, it is essential that the material forming the gun body he very hard so that essentially all of the force developed by the cartridge will be used in propelling the bullet and not absorbed by the material forming the gun body. Hardness is not the only characteristic needed, time to the force generated by the charge and the various conditions to which a perforating gun is subjected, it is essential that the heat treating process results in a material having high yield and tensile "ice strength. However, it is most difficult to properly heat treat a rather small diameter elongated object. In heat treating such an object there is a tendency to have longitudinal warping. Also there tends to be a difference in the characteristics from one end to the other, particularly since in the quenching process one end will enter the quenching bath at a different time than the other end. Accordingly, it is a further object to provide a multiple-shot well perforating bullet gun comprised of a plurality of individual gun sections which are so designed that they may be subjected to heat treating techniques which result in the material forming the gun section having substantially increased hardness as well as high strength characteristics.

One of the most common methods for serially attaching cylindrical bodies is by threaded engagement. However, in a selectively electrically fired multiple-shot perforating gun it is necessary to run lead wires from the firing mechanism to each of the individual gun units. Therefore, it is necessary that the various gun sections be aligned radially so that there will be a continuous passage for the lead wires from the firing mechanism to each individual gun unit. Also, for certain types of perforating operations it may be desirable to have all of the gun units fire along a common longitudinal axis; therefore, it is desirable that the assembly facilitates orientation of the gun units. Accordingly, it is a further object to provide a multiple-shot bullet perforating gun formed of individual gun sections which are detachably secured together by means which will permit madial alignment and orientation of all gun sections.

In order to accomplish the above objects and other objects which will become more apparent from detailed specification which will follow, the multiple-shot bullet perforating gun of the present invention is comprised of a plurality of individual gun sections each of which have an electrically actuated independent gun unit. The gun sections are serially attached together to form a multipleshot composite bullet perforating gun. To connect the gun sections together one end of each section is provided with a male boss and the other end is formed into a female socket which will matingly engage with a male boss from the adjacent gun section. To secure the assembled gun sections together there are aligned passages through the sections and rods having means for threaded engagement on their ends are positioned in the passages. The threaded ends extend past the upper and lower gun and are threaded into retaining means. The gun sections also have radially aligned passages providing a route for the lead wires from the firing mechanism to each individual gun unit.

Reference is now directed to the drawings in which:

FIG. 1 is an elevated view, partially in exploded form, of the multiple-shot well perforating bullet gun of the present invention.

FIG. 2 is a cross-section taken generally on line 22 of FIG. 1.

Referring now to the drawings, and in particular to FIG. 1, it can be seen that a multiple-shot well perforating bullet gun 8 of the present invention is comprised of a plurality of individual gun sections 10, a top sub 12 and a bottom sub 14, which are detachably secured together to form a unitary assembly. As is customary, the bullet perforating gun 8 is adapted to be lowered into a Wellbore by means of a cable (not shown) which is attached to a conventional cable head (not shown) located at the top of the gun 8. Between the cable head 18 and the top sub 12 there may be other interconnecting subs, one of which may contain suitable fire control means, indicated by the reference numbered 24. The present invention is not specifically concerned with the fire control means 24, however, it will be referred to in more detail subsequently. The bottom element 14 is so designed that another fire 3 controller section and a second series of gun sections may be attached to it or a bull plug 25, or other if terminating a gun, may be attached.

Each gun section is generally cylindrical in form and has a longitudinally extended fiat portion 26. A gun unit 28 which is shown in detail in FIG. 2, extends laterally inward from the flat portion 26. The present invention is not directed to a specific gun unit and the one illustrated is similar to that more fully disclosed in F. V. Porters U. S. Patent 2,953,971 dated Sept. 27, 1960.

To accommodate the gun unit 28, each individual gun section 10 has a pair of axially aligned laterally extending bores, 30 and 32, which extend inwardly from the flatted portion 26. The axes of the bores 30 and 32 are coin'ci dent with a center line through the cross section of the gun section, such center line intersects the flat portion 26. The intersection of the two bores 30 and 32 is located at a center line perpendicular to and bisecting the centerline extending through the fiatted portion 26. The smaller diameter bore 30 extends innermost and forms the firing chamber for the gun unit 28. Positioned in the firing chamber 30 is an annular shaped propellant charge 33. A bore 34 having an initial tapered portion 35 extends from the rear wall of the firing chamber 30 to a cylindrical recess or cavity 36 in the peripheral wall of the gun section 10. The tapered portion 35 of the bore 34 accommodates the head of a firing pin 38 which extends through the bore 34 into the cavity 36 where the electrical connection to the firing pin 38 is made. An annular seal receiving recess 40 is formed in the peripheral wall of the gun section 10 at the head of the cavity 36. A metallic seal 41 is sealingly engaged with the recess 40 to seal the cavity 36 thereby preventing the entrance of Well fluid into the gun unit 28.

The cylindrical wall of the outer bore 32 is formed into female threads to receive a threaded gun barrel 42 which has a central bore 44 accommodating a bullet 46. The outer end of the bore 44 is provided with a muzzle seal 47. The bullet 46 extends into the firing chamber 30* and into the bore of the annular propellant charge 33. Between the charge 33 and the back of the barrel 42, there is a gas seal 50 and a bullet retainer 52 which aid in controlling the initial departure of the bullet. As herein-before mentioned, reference is made to US. Patent 2,953,971 for more specific detail relating to details of construction and operation of gun unit 28. If desired other well perforating gun units may be utilized.

In effect, the essence of the present invention is directed to having individual gun sections 10 and the means by which the gun sections 10 are connected together and assembled with the top and bottom subs 12 and 14 to form the unitary gun assembly 8.

In order to serially connect the gun sections 10, one end of each gun section 10 is formed into a male boss 61] and the other end is provided with a female socket 62. The male bosses and the female sockets 62 are so designed and constructed as to make a snug mating fit as can be seen in FIG. 1. The individual gun sections 10 are serially connected together by engaging the male boss 60 of one gun section 10 with the female socket 62 of the succeeding gun section 10. The top sub or element 12 is provided with a female socket 64 which is designed so as to matingly receive the male boss 60 of the uppermost individual gun section 10. Also, the bottom sub or element 14 is provided with a male boss 66 which is designed so as to matingly engage the female socket 62 of the lowermost individual gun section 10. Although the individual gun sections 10 are connected together by the mating engagement of the male bosses 66 with the female sockets 62 and these connections are so designed as to take substantially all of the shock resulting from the firing of the individual gun units 28, additional means are provided to detachably secure the assembly together.

As can be seen in FIG. 2, there is a plurality of longitudinally extending passages 70 in each individual gun section 10. These passages 70 are on a common circumferential line and are so radially spaced that when the gun sections 10 are connected together with the flat portions 26 aligned, or the flat portions 26 are positioned 180 out of phase, there is a continuous passage from the uppermost gun section through the lowermost gun section, (see FIG. 1). The top sub 12 is provided with similarly aligned passages 72 and the bottom sub 14 has similar passages 74. As can be seen in FIG. 1 a cylindrical rod 76 which is provided with a male threaded portion 78 at each end thereof passes through each of the aligned passages formed by the passages 70 of the individual gun sections 10. The passages 72 in the top sub 12 are provided with female threads 80 and the male threaded portion 78 of each cylindrical rod 76 is threadingly engaged into the female threaded portion 80 of the passage 72. The passages 74 in the bottom sub 14 are not threaded and the lower threaded ends of rods 76 pass through the passages 74 and extend past shoulders 79 formed by recesses 81 in the bottom sub 14. Female threaded members 82 are threadin'gly engaged with the male threads 78 on the protruding portion of the rods 76 to secure the assembly together. As mentioned, the connection formed by the boss 60 and the socket 62 takes substantially all of the force resulting from firing the individual gun units 28 and the rods 76 are used to prevent the disengagement of the connections between :the gun sections 19.

Since the gun units 28 of the present invention are so designed to be electrically fired, it is necessary that lead wires extend from the firing control means 24 to each of the individual 26, therefore, it is necessary that passages be provided from the fire control means 24 to the individual gun units 28. Since these passages have to be radially aligned it would be difficult to use a threaded connection in order to connect the individual gun sections 10 together. In addition to the passages 70 which are for the purpose of receiving the threaded rods 76, each individual gun section 10 has two additional longitudinally extending passages 84 and 86 for the purpose of providing electrical supply to the individual gun units 28. The passages 84-86 are shown in FIG. 2, and are so located that they will be radially aligned throughout the length of the gun assembly either when the flatted portions 26 are in the same plane or 180 out of phase, thereby forming a route for the lead wires which run from the fire control means 24 to each individual gun unit 28. Extending from each of the cylindrical passages 84 is an angular passage 90 which extends cylindrical passage 84 to the opening 36. A string of lead wires 92 extends from the fire control means 24 down through the continuous passage formed by the passages 84 and when reaching the appropriate gun section 10, is threaded through the angular passage 90 into the cavity 36 for connection to the back of the firing pin 38.

Inasmuch as there .is a passage from the cylindrical passages 84 and 86 to the back of the gun unit 28, it is necessary that the passages 84 and 86 be sealed otf to prevent the entrance of well fluid. Accordingly, the passages 84 and 86 are provided with a counterbore 94 at each end of the gun section 10. A sleeve 96 is positioned in the aligned counterbores 94. Positioned between the sleeve 94 and the wall of the counterbore 94, there is an O-ring 98 (see FIG. 1) which acts as a seal to prohibit the entrance of Well fluid into the passages 84 and 86.

As can be seen, each gun section 10 is not much longer in length than the diameter of the gun unit 28, therefore, the individual gun sections 16 are relatively short and are easy to heat treat, especially when compared with the heat treating of the prior art gun bodies which are unitary assemblies extending almost five feet in length. In view of the short distance that a bullet from a well perforating gun travels prior to striking its target, it is essential that the heat treat of the gun body he at a maximum so that the force generated by the charge may be utilized to propel the bullet and not absorbed by the material forming the gun body. Moreover, the material from which the gun section is made and the heat treat to which it is subjected should be such that the material will have the requisite strength characteristics and will not be susceptible to stress corrosion as a well perforating gun is subjected to a Wide range of corrosive fluids in service.

As can be seen from the foregoing, the present invention discloses a multiple-shot bullet perforating gun having a plurality of gun sections which are connected together by shoe kabsorbing means and then detachably secured together by means passing through cylindrical passages in the assembly. The individual gun sections are so designed that they may be manufactured on a semi-quantity mass production basis and be oriented to properly form the continuous passages and align the gun units. Also the gun sections are of such size that they can be properly heat treated to obtain the desired hardness and strength.

While a preferred form of the invention has been shown, it is understood that various changes may be made in its construction by those skilled in the art without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A multiple-shot bullet perforating gun comprising:

a top element having means at its upper end for attachment to gun lowering means, a female socket in its lower end, a plurality of threaded bores extending upward from the lower end and a longitudinally extending through passage;

a plurality of generally cylindrical individual gun sections having a longitudinally extending fiatted portion,

a pair of axially aligned transverse bores extending inward from the flatted portion receiving a gun unit, the smaller diameter bore extending innermost and forming a firing chamber and the larger bore provided with means to receive a detachable gun barrel,

the lower end of each gun section provided with a female socket having the same size and configuration as the female socket of the top element,

the upper end of each gun section formed into a male boss of such size and configuration as to mate with the female sockets of the top element and gun sections;

. a plurality of longitudinally extending cylindrical passages in each gun section, radially alignable with the threaded bores of the top element;

a plurality of lead wire passages extending longitudinally through each gun section, a counterbore at each end of the lead wire passage of the top gun section radially alignable with the through passage of the top element, an angular extending passage from said passage to the rear of the gun unit,

the first gun section attached to the top element by mating engagement of its male boss with the female socket of the top element,

the remaining gun sections serially connected to the first gun section by mating engagement of the male boss of one with the female socket of another, the cylindrical passages mating to form continuous passages and the lead wire passages aligned to form a continuous lead wire passage;

i cylindrical sleeves positioned in the mating counterbores of the aligned lead wire passages;

O-rings positioned between the sleeve and the counterbores to seal the lead wire passages and prevent the entry of well fluid to the gun unit;

a cylindrical rod having threated ends passing through each of the continuous passages formed by the cylindrical passages of the gun sections, the upper threaded end of each cylindrical member threadingly engaged with a threaded bore of the toy element;

a bottom element having its upper end formed into a male boss of such size and configuration as to mate with a female socket of a gun section and having a plurality of longitudinally extending passages radially alignable with the cylindrical passages of the gun sections, the male boss engaged with the female socket of the lowermost section;

female threaded members threadingly engaged with the lower threaded ends of the cylindrical rod securing the toy element, the gun sections, and the bottom element together.

2. A multiple-shot bullet perforating gun comp-rising:

a top element having means at its upper end for attachment to gun lowering means, a female socket in its lower end, a plurality of threaded bores extending upward from the lower end, and at least one 1011gitudinally extending through passage;

a plurality of generally cylindrical individual gun sections having a longitudinally extending flatted portion, I

the lower end of each gun section provided with a female socket of the same size and configuration as the female socket of the top element,

the upper end of each gun section formed into a male boss of such size and configuration as to mate with the female sockets of the top element and gun sections,

a plurality of longitudinally extending cylindrical passages in each gun section, radially alignable with the threaded bores of the top element,

at least one other longitudinally extending passage radially alignable with the through passage of the top element,

an angular extending passage from said passage to the rear of the gun unit;

the remaining gun sections serially connected to the first gun section by mating engagement of the male boss of one with the female socket of another, the cylindrical passages mating to form continuous passages;

a cylindrical rod having threaded ends passing through each of the continuous passages, the upper threaded end of each cylindrical member threadingly engaged with a threaded bore of the top element;

a bottom element having its upper end formed into a male boss of such size and configuration as to mate witha female socket of a gun section and having a plurality of longitudinally extending passages radially alignable with the cylindrical passages of the gun sections, the male boss engaged with the female socket of the lowermost gun section;

a female threaded members threadingly engaged with the lower threaded ends of the cylindrical rods securing the top element, the gun sections and the bottom element together.

3. A multiple-shot bullet perforating gun comprising;

a top element having means at its upper end for attachment to gun lowering means, a female socket in its lower end, a plurality of threaded bores extending upward from the lower end;

a plurality of generally cylindrical individual gun sections having a longitudinally extending flatted portion,

a pair of axially aligned transverse bores extending inward from the flatted portion receiving a gun unit, the smaller diameter bore extending innermostand forming a firing chamber and the larger bore provided with means to receive a detachable gun barrel,

the lower end of each gun section provided with a femal socket having the same size and con figuration as the female socket of the top element,

the upper end of each gun section formed into a male boss of such size and configuration as to mate with the female sockets of the top element and gun sections, 7

a plurality of longitudinally extending cylindrica passages in each gun section, radially alignable with the threaded bores of the top element;

a cylindrical rode having threaded ends passing through each of the continuous passages formed by the cylindrical passages in the gun section, the upper threaded end of each cylindrical member threadingly engaged with a threaded bore of the top element;

a bottom element having its upper end formed into a male boss of such size and configuration as to mate with a female socket of a gun section and having a plurality of longitudinally extending passages radially alignable with the cylindrical passages of the gun sections, the male boss engaged with the female socket of the lowermost gun section;

female threaded members threadingly engaged with the lower threaded ends of the cylindrical rod securing the top element, the gun sections and the bottom element together.

4. A multiple-shot bullet perforating gun comprising:

a pair of axially aligned transverse bores extending inward from the flatted portion, the axes of said bores being coincident with a center line of a cross section through the gun section, said center line bisecting the fiatted'portion, the intersection of the two bores being located at approximately a center line perpendicular to the center line extending through the flatted portion, the smaller diameter bore portion forming a firing chamber and the larger diameter bore portion provided with means to receive a detachable gun barrel,

one end of each gun section formed into a male boss,

the other end of each gun section provided with a female socket,

a plurality of longitudinal cylindrical passages in each gun section, the center of each passage located on the same circumferential line and radially spaced in such a manner as to be mating when either the flatted portions are aligned or 180 out of phase, the gun sections serially connected together by mating engagement of the boss of one gun section with the socket of another, the cylindrical passages being radially aligned to form continuous passages extending from the upper gun section through the lower gun section;

cylindrical rods having threaded ends passing through the continuous passages;

means secured to the threaded ends of the cylindrical rods securing the connected gun sections together.

5. A multiple-shot bullet perforating gun comprising:

8 a plurality of generally cylindrical individual gun sections having a longitudinally extending fiatted portion,

a pair of axially aligned transverse bores extending inward from the flatted portion receiving a gun unit, the smaller diameter bore portion forming a firing chamber for the gun unit and the larger diameter bore portion provided With means to receive a detachable gun barrel of the gun unit; a one end of each gun section formed into a male boss,

the other end of each gun section provided with a female socket,

a plurality of longitudinal cylindrical passages in each gun section, the center of each passage located on the same circumferential line and radially spaced in such a manner as to be mating when either the flatted portions are aligned or out of phase, the gun sections serially connected together by mating engagement of the boss of one gun section with the socket of another, the cylindrical passages being radially aligned to form continuous passages extending from the upper gun section through the lower gun section;

cylindrical rods having threaded ends passing through the continuous passages;

6. A multiple-shot bullet perforating gun comprising:

a plurality of individual gun sections, each gun section having an independent gun unit,

one end of each gun section formed into a male boss and the other end provided with a female socket,

a plurality of longitudinal securing passages in each gun section, V

a plurality of lead wire passages in each gun section, one of said lead wire passages communicating with the rear of the gun unit, each end of thelead wire passages having a counterbore,

the gun sections being serially connected together by mating the male boss of one section with the female socket of a succeeding section with the longitudinal securing passages being radially aligned to form continuous attaching passages and the lead wire passages being radially aligned to form continuous lead wire passages;

sleeves positioned in the mating counterbores of the lead wire passages;

O-rings positioned between the sleeves and counterbores to seal the lead Wire passages and prevent entry of Well fluid into the gun unit;

means extending through the continuous attaching passages to secure the connected gun sections together.

7. A multiple-shot bullet perforating gun comprising:

a plurality of longitudinal securing passages in each gun section,

a plurality of lead wire passages in each gun section, one lead Wire passage having an angular passage extending to the rear of the gun unit, 7

the gun sections being serially connected together by mating the male boss of one section with the female socket of a succeeding section with the longitudinal securing passages being radially aligned to form a continuous attaching passage and the lead wire passages being radially aligned to form continuous lead Wire passages;

seal means at each end of each gun section about the lead wire passages to seal the lead Wire passages preventing entrance of Well fluid into the gun unit; means extending through the continuous attaching passages to secure the connected gun sections together. 8. A multiple-shot bullet perforating gun comprising: a plurality of individual gun sections, each gun section having an independent gun unit,

one end of each gun section formed into a male boss and the other end provided with a female socket, a plurality of longitudinal securing passages in each gun section, a plurality of lead wire passages in each gun section, the gun sections being serially connected together by mating the male boss of one section with the female socket of a succeeding section with the longitudinal securing passages being radially aligned to form continuous attaching passages and the lead wire passages 10 being radially aligned to form continuous lead wire passages, means extending through the continuous attaching passages to secure the connected gun sections together, sealing means located in each gun section preventing entrance of Well fluid into the gun unit through said lead wire passages.

References Cited

UNITED STATES PATENTS

2,3 31,057 10/ 1943 Spencer 175-459 2,889,774 6/1959 Allen 175-459 X FOREIGN PATENTS 546,812 10/1957 Canada. 687,790 5/1930 France.

CHARLES E. OCONNELL, Primary Examiner.

20 D. H. BROWN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,327,793 June 27, 1967 Forrest V. Porter It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 29, for "madial" read radial column 5 line 11 for "shoc kabsorbing" read shock absorbing line 52, after "passage" insert the lead wire passage H column 5, line 75, and column 6, line 10, for "toy", each occurrence, read top column 6, line 61, strike out "a"; column 7, line 23, for "rode" read rod column 8, lines 71 and 72, for "securing passages being radially aligned to form a continuous attaching passage and the lead wire pas" read securing passages being radially aligned to form a continuous attaching passages and the lead wire pas- Signed and sealed this 18th day of June 1968. (SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer

Claims

8. A MULTIPLE-SHOT BULLET PERFORATING GUN COMPRISING: A PLURALITY OF INDIVIDUAL GUN SECTIONS, EACH GUN SECTION HAVING AN INDEPENDENT GUN UNIT, ONE END OF EACH GUN SECTION FORMED INTO A MALE BOSS AND THE OTHER END PROVIDED WITH FEMALE SOCKET, PLURALITY OF LONGITUDINAL SECURING PASSAGES IN EACH GUN SECTION, A PLURALITY OF LEAD WIRE PASSAGES IN EACH GUN SECTION, THE GUN SECTION BEING SERIALLY CONNECTED TOGEHTER BY MATING THE MALE BOSS OF ONE SECTION WITH THE FEMALE SOCKET OF A SUCCEEDING SECTION WITH THE LONGITUDINAL SECURING PASSAGES BEING RADIALLY ALIGNED TO FORM CONTINUOUS ATTACHING PASSAGES AND THE LEAD WIRE PASSAGES BEING RADIALLY ALIGNED TO FORM CONTINUOUS LEAD WIRE PASSAGES, MEANS EXTENDING THROUGH THE CONTINUOUS ATTACHING PASSAGES TO SECURE THE CONNCECTED GUN SECTION TOGETHER, SEALING MEANS LOCATED IN EACH GUN SECTION PREVENTING ENTRANCE OF WELL FLUID INTO THE GUN UNIT THROUGH SAID LEAD WIRE PASSAGES.