US 2960930 A
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Nov. 22, 1960 F. H. BELL WELL PERPORATING APPARATUS Filed April s, 1957 2 Sheets-Sheet 1 lNvENToR Frederick H. Bell BY 'M ATTORNEY Nov. 22, 19h() F. H. BELL WELL PERFORMING APPARATUS 2 Sheets-Sheet 2 'Filed April 3, 1957` INVENTOR Frederick H. Bell BY (Q ATTORNEY United States Patent C WELL PERFoRATING APPARATUS Frederick H. Bell, Arlington, Tex., assigner to Jet Research Center, Inc., Arlington, Tex., a corporation of Texas Fixed Apr. s, 1957, ser. No. 650,335
7 claims. (ci. 1oz- 20) This invention relates to well perforating apparatus and more particularly to such apparatus in which individual shaped explosive charge units are linked toygether to form a chain of units. The invention also relates to the individualV shaped charge explosive units themselves.
In the perforation of oil wells, it is desirable to have perforating apparatus that may be quickly assembled in the eld to provide a perforating gun of a length and having a number of perforating units suited to the job at hand. For the sake of simplicity and speed of operation, it is also desirable that a minimum number of tools be needed to assemble the perforating apparatus.
Frequently, oil wells are completed by so-called permanent type completion methods. In these methods, tubing is set in the casing and the top of the casing is capped with the usual well head equipment prior to performance of the perforating step. Perforating apparatus is then lowered by cable through the tubing and out of its lower end to the level at which the casing is to be perforated and the apparatus is fired. Any parts of the perforating apparatus that remain attached to the cable after firing are retrieved by withdrawal through the tubing. For these purposes, the perforating apparatus must be as efficient as possible. One requirement is that the apparatus must have a close sliding fit in the tubing in order to accommodate the largest possible quantity of explosive in each perforating unit which is designed to fire generally laterally of the well bore. At the same time, the apparatus must not bind in the tubing during descent.
The permanent type completion method is being adapted to directional wells wherein the well may be drilled vertically for a certain distance down from the earths surface, and thereafter drilled at an angle to the vertical. Also, in some offshore installations the production tubing may rise vertically from the bottom of the well and thereafter be turned landward and run to the shore. In either case, the tubing is rather sharply bent at certain points which makes it very diicult to run perforating apparatus through the tubing.
An object of the invention is to provide a well perforating apparatus which may be quickly assembled in the iield principally from a plurality of identical, shaped explosive charge units. Due to the special construction of the charge units, such assembly may be accomplished without the use of tools.
Another object is to provide a perforating unit, a plurality of which may be linked together to form a perforating assembly of any desired length.
Another object of the invention is to provide a perforating assembly having articulated joints and being adapted to pass through relatively sharp bends in small dented or otherwise damaged to a limited degree, as by, being burred or somewhat corroded in the bore. Still another object is to provide apparatus for perfo@V rating oil, gas and water wells that may be employed in permanent type completion methods. Yet another object of the invention is to provide wellV perforating apparatus that is relatively simple and inexpensive to manufacture and that may be conveniently and rapidly assembled in the eld. Y Another object of the invention is to provide a well perforating apparatus including a plurality of capsulated shaped explosive charge perforating units linked together by a pivotal linkage construction having cooperating stops for limiting relative pivotal movement ofv adjacent units. Another object of the invention is to provide blank interval members in a well perforating apparatus of the character disclosed which members carry no perforating charges but are linked in the assembly like theperforating units themselves.
These and other objects and -advantages of the inven l tion as may appear hereinafter are achieved in a well perforating apparatus that is adapted to Vbe passed through small diameter tubing having relatively sharp bends which includes a plurality of longitudinally aligned well perforating units, articulated means linking adjacent units together to form a chain, and means limiting the angular movement of adjacent perforaiting units about the included linking means. The articulated joints lend flexibility to the chain of units permitting it to pass through sharply curved sections of narrow tubing. The articulated joints may include a pivot pin carried by one unit received in a complementary hole provided in an adjacent unit. Such joints may include a key or the like that retains the pivot pin in the hole and comple mentary stop means on adjacent units limiting their relative' angular movement about the pivot point. More particularly, the shaped explosive charge well perforating apparatus of the invention has a plurality of vertically aligned well perforating units, each unit including a pressure resistant, frangible container having a shaped explosive charge therein adapted upon detonation toV project an explosive jet outwardly through a wall of the container and having a vertical axis' intersecting the axis of the explosive jet at a substantial angle, the vertical axes of the unit being in alignment to define the vertical axis of the well perforating apparatus; the container of each unit having an upstanding and a'depending arm; one of said arms having a terminal planar face containing the vertical axis of the unit; a cylindrical pin carried by said one arm, the pin extending'from the terminal face and having its axis intersecting the vertical axis of the unit at right angles, the pin providing a trans verse keyhole therethrough spaced from the terminal face, and a lug extending radially from the pin between the terminal face and the keyhole. The other of the arms has a Iterminal planar face containing thevertical axis of the unit, the other arm providing a cylindrical hole therethrough having its axis intersecting the vertical axis of the unit at right angles within the terminal planar face, the other arm having a lug-receiving recess communicating with the ho-le and extending radially' outwards therefrom. The perforating unitsV are linked to gether to form a chain wherein the pin on the onearm of one unit is received in the hole of the other armof an adjacent unit, the terminal faces of the arms are'in abutment and the lug is received in the recess, the sides of the lug being spaced from the sides of the recess to limit arcuate movement of the pin in the hole, and a `key is disposed in the keyhole of the pin to retainthe arm of the adjacent unit in the pin.
The present inventionis an'improvement inthe in# Patented Nov. 22, 1960 vention disclosed and generically claimed in the copending application of Blake M. Caldwell, Serial No. 650,334, led April 3, 1957, for Well Perforating Apparatus, which copending application is assigned to the same assignee as the present application.
The invention will be described with greater particularity with reference to the drawings in which:
` Fig. 1 is a vertical sectional view through a portion of an oil well showing an exemplary embodiment of the weli perfor/ating apparatus of the invention suspended in the well;
Fig. 2 isv an enlarged elevational View of one of the shaped charge perforating units used in the apparatus of Fig. 1;
i Fig. 3 is a right hand side view of the shaped charge perforat'ingf unit of Fig. 2, parts of -the shaped charge container being broken away;
` Fig. 4 isa plan view thereof;
Fig. 5 is a bottom view thereof;
Fig. 6 is a still further enlarged fragmentary view showing one of the articulated joints of the well perforating apparatus;
Fig. 7`is a left hand view of the joint shown in Fig. 6;
Fig. 8 is an elevational view of aV blank interval unit; and
""Fig. 9 is a left hand view of the blank interval unit shown in Fig.V 8.
-Referring to the drawing, particularly to Fig. 1, there is shown a section of an oil well having a casing 10 in which production tubing 11 is set. The perforating apparatus of the invention is shown as being suspended from lthe cable 12 which carries, as is conventional, a conductive wire through which current is passed for the purpose of ring the well perforating apparatus. The well perforating apparatus is lowered from the surface of the earth in well known manner.
' The cable head 13 hangs from the lower end of the cable. From the bottom of the cable head an arm 14 depends, and this arm supports a plurality of interlinked,
shaped explosive charge, well perforating units desig-` nated by the general reference numeral 15. The perforating units are red in a manner to be explained more fully hereinafter by a detonating fuse or Primacord 16 disposed adjacent the rear ends of the shaped charge units. Aixedrto the lower end of the Primacord 16 in detonating relation thereto is a detonator or blasting cap 17.A A pair of wiresv18, through which igniting current is conducted to the blasting cap 17, extend from theblasting cap and are wound in an upward direction about the chainof perforating units to enter the cable head 13 in which they are connected to the tiring circuit.
.The perforating apparatus is seen partially inside of the lower end of the tubing 11. Before, firing itis lowered below the bottom of the tubing to a point opposite the section ofthe casing to be perforated.
Referring to Figs. 2 through 5, the perforating unit ofthe invention has a charge case 19 closed at its rear end by a cap 20. The cap fits tightly in the rear end ofthe case and the case may be sealed against ingress of bore fluids by means of an O-ring 20a or similar compressible seal interposed between the cap and the case. Disposed within the case near the rear end thereof is a charge of compressed high explosive 21 having a forwardly facing cavity therein lined with an inert liner 22, preferably of copper or other metal. Stand-01Tr space is provided between the front face of the liner 22 and the front wall 23 of the charge case to permit the perforating jet to form Within the case upon detonation of the charge. Y
The cap 20 has a rearwardly projecting cylindrical boss 24 through which is bored a vertically extending fuse passage 2,5. As `shown in Fig. 5, the cap 20` hasa .booster cayity 26 separated from the fuse ,passage.25by a thin wall 27' through which detonating energy fronjrthe P rimj asord, Strang-nite@ to; a,-.b 19Ste -har.ge die cavity- The booster charge initiates the main explosive charge 21 to produce an explosive jet from the liner, the jet being projected forwardly along the cylindrical axis of the charge. This jet forms in the air space forwardly of the liner 22 and penetrates the front wall 23 of the charge case. Thereafter it penetrates the wall of the adjacent casing and perforates the surrounding earth formation. Upon detonation, some of the energy of the explosive charge serves to break or fracture the charge case and arms, formingl small fragments and particles that fall harmlessly to the bottom of the Well.
The charge case has an upstandng arm 27, the face 28 of which contains the vertical center line CL of the unit. The face 28 is disposed at right angles yto the charge axis. From the upper terminal end of the face 28 a cylindrical pivot pin 29 extends perpendicularly, the axis of the pin intersecting the center line. A lug 30 projects radially frornk the side of the pin 29 and, extends in aY direction upwardly alongy the center line CL. The lugY also extends axially along the side, of the pin 29 to a point near theY hole. or keyway 50 and between the hole 50 and the arrn f ace 28; A key 51 is inserted through the hole 50 in linking the charge units together, asV will be explained more fully hereinafter. As shown, the. upstanding arm 27' is of yuniform thickness; however, the thickness does1 not, have to be uniform as long `asv the terminal end. of the planar face 2 8- adjacent the pin 29 is in a plane containingl the center line.
The case. of*V the unit also has a depending arm 3'1 which, in the embodiment shown, is` of the same length as the upstanding arm 27'. The surface 32 of the depending arm contains the center line of the perforating unit. A cylindrical hole 3 3 isformed' in the lower end ofthe depending arm.` This hole is` at right angles to` the plane ofV the surface 32 and its axis intersects the center line. Extending upwardly from the hole 33y is an arcuateslot 34 thatcommunicates the hole andj extends in a vertical' direction along the center line CL ofthe perforating unit. The arcuate slot extendsentirely through the ar1n351., Itv
receives the lug 3d of a subjace'nt perforating unit when the apparatus is assembled and' limits the pivotal movement ofl adjacent perforatingl units. In, the particular form shown, the terminal end ofthe depending arm is of uniformV thickness and the lower endof the 'facel 32j contains the center linie. However, the end of the arm near the case mayV` be thicker or, thinner than shown as desired; It will b e noted; that the depending arm makes an angle of 30"L with the axis ofthe shaped explosive charge as bestrseen inl Fig. 5..
Figs. 6 and 7 show inv enlarged fragmentary detail the mannerin which theupstanling arm 27'ofone perforating unit is linkedtothefdepending `arm 31 of an immediately superjacent.shaped'charge unit. Itwill be seen ,that the pin y29'is receivediin the lroler33` with the lug 30; disposedjin the arcuateslot 34.` A cotter key 531V is inserted in the keyway Stl'ofthe pin29rand the ends of the cotter keyv are bentover as shown to secure the depending arm 31 of the upper perforating unit to the pin 29. Asclearly shown in Fig. 6.,'l the lug Y1.20 is .narrower than the arcuate slot 3.4,so that a limitedpivoting of the arm 31 yon the pin 29 is permittedjbefore the sides of the lug engage the sides of the arcuate slot to stop the pivotal movement in either direction. In practice, it has been found that a pivotal movement of from a few degrees to as much as 30 to 45 is desirable andthelug and arcuateslot may be` proportionedtorpermit any desired pivotal movement. The diameter of theghole 33,-issomewhat greaterv than thediameterroffthe pin 29 providing a loose-fit, ofy the pin in the hole. Itis also seenthat/ the radiusl of the lug 30 is. somewhat smallenl than; the Vvradius of the arcuate slot 34.whicha ls oprovid e s aloo se t Referring to Fig.- 7 it is seen@ that -the'distancebfronjr theA terminal vplanar -face 28 Offfhezntrlfte the Cotter-.key 5ltis1s0mewhatf-greater tha 1111 thCkneSs/Offfhe depending-anvil.. providing fcrratfreest Otrtlaefanallbetweensthe; cottenkeyf'and the a'rm A27. This free lit allows limited rocking movement in the plane of the drawing of Fig. 7 of the arm 31 in relation to the arm 27 and thus enhances the flexibility of the assembled perforating gun.
It will be apparent that the perforating units may be readily linked together and unlinked without the use of any tools, it being merely necessary to manually insert or remove the cotter key 51. As is seen from Fig. 7, the terminal planar face 32 of the arm 31 is opposed to the terminal planar face 28 of the arm 27 when the units are properly assembled. Thus, the center lines of adjacent charge units are substantially in alignment.
The charge units in assembled relationship as shlown in Fig. l are adapted to be run through narrow tubing with close clearance. For this purpose, the charge containers are especially dimensioned to provide surfaces that will slide through narrow tubing without binding and will maintain alignment of the charge units. As seen in Figs. 3, 4 and 5, the front face 23 of the charge case is a segment of -a sphere having its center on the center line of the charge unit at its intersection with the horizontal axis of the charge case 19. The boss 24 has a spherical rear face with its center at the same point and having the same radius as the front face 23. The circular rear edge of the charge case 19 lies in this sphere as does also the circular forward edge of the charge case Where the spherical front face 23 intersects the cylindrical portion of the case 19. Thus it is seen that the charge case and cap provide a container in which all surfaces that can slide against the tubing are located on a spherical surface having its center on the center line of the perforating unit and preferably at a point midway between the axis of the pin 29 and the axis of the hole 33. Whereas, the arms 27 and 31 are shown as being of equal length, it will be understood that they may have dilferent lengths, if desired, or they may be proportionately longer for shorter than shown in the drawings.
Owing to the hereinbefore described geometery of the charge unit, a linked assembly of such units will readily pass through a straight length of tubing having a bore with a diameter only slightly larger than the diameter of the spherical surface containing the faces and edges of the charge container that make sliding contact with the bore of the tubing. These faces and edges are termed the skating faces of the charge container, since they slide or skate along the bore of the tubing. Such an assembly of units is free to rotate on lits vertical axis within the confines of closely itting straight tubing without substantial lateral displacement of any of the units from alignment with the Vertical axis of the assembly and without becoming lodged in the tubing as it is lowered therethrough. Moreover, the articulated joints linking adjacent units together and the angular phasing of such joints about the vertical axis of the assembly allow the assembly to pass readily through rather sharply curved lengths of closely fitting tubing.
The foregoing is exemplified in an actual embodiment of the invention constructed in accordance with the acoom-panving drawing in which the distance between centers of the pin 29 and the hole 33 was 3, the diameter of the spherical surface containing the aforementioned faces and edges of the charge container was 11%6, and the center of the spherical surface was located on the center line of the charge unit midway between the pin 29 and the hole 33. Ten charge units so constructed and dimensioned when linked together to form a chain, as shown in Fig. l, were found to run freely in straight lengths of tubing having a bore measuring 2" in inside diameter and to negotiate bends in such tubing having a radius of 5 withlout binding or becoming lodged therein.
In preparing or assembling a perforating gun in the field, a charge 15 is linked to the arm 14 of the cable head 13. The arm 14 has a hole and arcuate slot there thro-ugh, similar to the hole and arcuate slot of the charge unit hereinbefore described, in which the linking pin of the topmost charge unit is inserted. As many additional perforating units as desired are added to form a chain of units. It will be seen that adjacent charge units are disposed at an angle of to each other about the vertical axis of the assembly. Detonating fuse 16 is threaded through the passageways 25 of the perforating units and wound about the assembly in helical disposition as shown. The lower end of the fuse 16 is equipped With a detonator 17, the wires 18 of which are led upwardly to the cable head in which they are connected to the firing circuit whereby the detonator may be initiated from the surface of the earth. The assembly is lowered into the well as shown in Fig. l to the desired level. The tiring circuit is energized. The blasting cap 17 detonates the Primacord 16 which practically simultaneously detonates the individual perforating units 15 to perforate the casing and surrounding earth formation. The charge units 15 are frangible and are broken into small fragments which fall to the bottom of the well as innocuous debris. The cable head 13 is of massive construction and is not destroyed by the explosion. It is withdrawn after tiring for re-use.
While the well perforating unit shown in the drawings has but a single hole 33 in the depending arm 31, it is contemplated that an additional hole or holes of the same kind may be formed in the arm 31, thus giving a selection of holes in any one of which the pin of an adjacent unit may be inserted, whereby the spacing of the charges may be varied in assembling the units. The plurality of holes are spaced along the center line of the charge unit. Score marks may be made between adjacent holes along which that portion of the arm 31 below the hole that is Vselected for use may be broken olf and discarded.
A blank interval member or unit 52 is shown in Figs. 8 and 9. This unit has an elongated flat body 53 having a pin 29' at the upper end provided with a keyway 50' and a lug 30' similar to the pin and lug construction o-f the perforating unit shown in Figs. 2 through 5. The axis of the pin 29 intersects the center line at right angles as best seen in Fig. 9. At the lower end of the blank interval unit is provided a liange 54 that lies in a plane at right angles to the plane of the body 53. The surface 55 of the flange includes the center line CL. A cylindrical hole 33 is formed through the flange 54 and a connected -arcuate lug receiving slot 34' is also provided for purposes similar to the hole 33 and arcuate slot 34 in the depending arm 31 ofthe shaped charge unit shown in Figs. 2 through 5. Although the flange 54 of the illustrative blank interval unit is shown as being at right angles to the plane of the body 53 and parallel to the axis of pin 29', it will be understood that this angle may be varied as desired.
It will be apparent that one or any number of the blank interval members may be inserted in or substituted for the shaped charge explosive units 15 in the assembly shownin Fig. lV where it is desired to space the active charge units 15 at desired vertical intervals.
From the foregoing description of -a typical embodiment of the invention, persons skilled in the art will readily perceive a wide variety of variations and modifications coming within the spirit of the invention and the scope of the claims. For example, it is contemplated that the detonating fuse 16 may be tired from the top instead of from the bottom by merely changing the position of the blasting cap 17. it is also contemplated that the lower end of the assembly may be provided with a suitable bull plug if desired. lt is also contemplated that the perforating units need not embody shaped explosive charge devices; instead, they may include bullet perforating devices. Although, in the illustrative chain of units herein disclosed, adjacent charges are phased at angles of 120 to each other, any other convenient phase angle may be employed; for example angles of 60, 90 or 180 may be found convenient, or all charges may face in the same direction.
1. Shaped explosive charge well perforating apparatus adapted to be passed through small diameter tubing having relatively sharp bends comprising: a plurality of vertically aligned well perforating units, each unit including a pressure resistant, frangible container having a shaped explosive charge therein adapted upon detonation to project an explosive jet outwardly through a wall of the container and having a vertical axis intersecting the axis of the explosive jet at a substantial angle, the vertical axes of said units being in alignment to define the vertical axis of the well perforating apparatus; the container of each unit having a single upstanding and a single depending arm; one of said arms having a terminal planar face containing the vertical axis of said unit; a cylindrical pin carried by said one arm, said pin extending perpendicularly from said terminal face and having its axisv intersecting the vertical axis of said unit, said pin providing a transverse keyhole therethrough spaced from said terminal face, and a lug extending radially from said pin between said terminal face and said keyhole; the other of said arms having a terminal planar face containing the vertical axis of said units, said other arm providing a cylindrical hole therethrough extending perpendicularly to the terminal planar face and having its axis intersecting the vertical axis of said unit, said other arm having a lug-receiving recess communicating with said hole and extending radially outwards therefrom; said perforating units being linked together to form -a chain wherein the pin on the one arm 4of one of said units is receivedv in the hole of the other arm of an adjacent unit, the terminal faces of said arms are in abutment, and said lug is received in said recess, the sides of said lug being spaced from the sides of said recess to limit arcuate movement of said pin in said hole; and a key disposed in the keyhole of the pin of said one arm retaining the arm of the adjacent unit on the pin.
. 2. Well perforating apparatus adapted to be passed through small diameter tubing having relatively sharp bends comprising: a plurality of vertically aligned well perforating units; each unit having a -single upstanding and a single depending arm; each of said arms having a terminal planar face, said terminal planar faces containing at least one common straight line; said units being assembled with the terminal planar face of the depending arm of each unit abutting the terminal planar face of the upstanding arm of the immediately subjacent unit; pivot means interconnecting adjacent units for relative pivotal movement of said adjacent units about an axis'extending perpendicularly from said abutting planar faces and intersecting said common straight line; complementary pivot interlocking ymeans carried by said arms; and complementary stop means carried by said arms limiting relative pivotal movement of the units about the axis of said pivot means.
3. Well perforating apparatus as defined in claim 2 wherein said pivot means includes a pin extending fromone of said abutting planar faces received in a complementary hole extending from the other of said abutting planar faces.
4. Well perforating apparatus as defined in claim 2 tending radially from said hole.
5. Well perforating apparatus as defined in lclaim 2 wherein said pivot means includes a pin extending from one of said abutting planar faces received in a hole extending from the other of said abutting planar faces, said complementary stop means includes a lug extending radially from said pin received in an arcuate slot extending radially from said hole, and means preventing withdrawal of said pin from said hole.
6. A well perforating unit comprising: a container having an explosive charge therein adapted to project a perforating means outwardly therefrom; a single upstanding unit-interconnecting arm on said container; a single down- Wardly extending unit-interconnecting arm on said container; each of said arms having a terminal planar face; said terminal planar faces containing at least one common straight line; complementary pivot means carried by said arms and extending perpendieularly one from each of said terminal faces with the pivot axes of said pivo-t means intersecting said common straight line; complementary pivot interlocking means carried by said arms; and complementary pivotal-movement-limiting stop means carried by said arms.
7. A well perforating unit as dened in claim 6 wherein said complementary pivot means includes a pin extending from one of said terminal faces and a hole extending from the other of said terminal faces; and wherein said complementary pivotal-movement-limiting stop means includes a lug extending radially from said pin and an arcuate slot extending radially from said hole, said slot having a greater radius and a greater arcuate length than said flug, said lug and said slot each being spaced the same distance from the terminal planar face of its respective arm.
References Cited in the le of this patent UNITED STATES PATENTS 548,899 Wade Oct. 29, 1895 1,598,293 Luck Aug. 31, 1926 2,026,061 Prikel Dec. 3l, 1935 2,616,370 Foster Nov. 4, 1952 2,633,329 LeBus Mar. 31, 1953 2,799,224 Long July 16, 1957 2,853,944 Robertson Sept. 30, 1958 FOREIGN PATENTS 701,074 Great Britain Dec. 16, 1953