US2981185A

US2981185A - Well perforating apparatus

Info

Publication number: US2981185A
Application number: US650334A
Authority: US
Inventors: Blake M Caldwell
Original assignee: Jet Research Center Inc
Current assignee: Jet Research Center Inc
Priority date: 1957-04-03
Filing date: 1957-04-03
Publication date: 1961-04-25
Anticipated expiration: 1978-04-25

Description

April 25 1961 B. M. CALDWELL 2,981,185

WELL PERFORATING APPARATUS Filed April 5, 1957 1NVENT0R Blake M. Coldwell BY W ATTORNEY l forating apparatus through the tubing.

e A2,981,135 Y WELL PERFoRATnuG APPARATUS Blake M. Caldwell, Fort Worth,r Tex., assigner to Jet Research Center, Inc., Arlington, Tex., a'corporation of Texas Filed Apr. s, 1957, ser. No. 656,334

s claims. -(ci. 1oz-zo) This invention relates vto Well perforating apparatus and more particularly to such apparatus in which individual shaped explosive charge 'units are linked together to form a chain of units. the individual shaped charge.r explosive units themselves.

In the perforation of oil wells, vit is desirable to have perforating apparatus that maybe quickly assembled in the field to provide a perforating gun of a length and havf ing 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 setin the casing and the top of the casing is capped with the usual well head equipmentprior toperformance of the perforating step. Perforating apparatus is then lowered by'cable through the tubing and out of its lower end tothe level at which the casing is to be perforated and the apparatus is red. Any parts of the perforating apparatus that remain attached to the cable after tiring are retrieved by withdrawal through the tubing. For these purposes, the perforating apparatus must be as eflcient as possible. One requirement is that the apparatus must have a close sliding t in the tubing in order to accommodate the largest possible quantity of explosive in each perforating unit which is designed to lire generally laterally of the well bore. At the vsame time, the apparatus must not bind in the tubing during descent. f

The permanent type completion method is being vadapted to directional wells wherein the well may be drilled vertically for a certain ydistance down from the earths surface, and thereafter drilled at an angle tothe tion" tubing may rise vertically from the bottom of the shore. vIn either case, the tubing is rather'sharply bent at certain points which makes it very diflicult to run per An object of the invention is to provide a Well perforatingapparatus which may be quickly assembled in the eldy 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. K

Another object ofthe invention is to provide a perforating assembly having articulated joints and being adapted to pass through relatively sharp bends in small diameter tubing. `In addition to being adapted to pass through relatively sharp bends that are purposely made The invention also-relates to vertical. Also, in some oiishore installations the produc- Y in tubing, it is a further object of the invention to pro-y vide a perforating assembly that can be run 'through closely fittingl tubing that is inadvertently bent, twisted,r-

dented or otherwise damaged to a limited degree, as by being bm'redvors'omewhat corroded in the bore.

-the well perforating apparatus.

2,981,185 latented Apr. 25, 1,961,

J perforating apparatusthat is relatively simple and inexpensive to manufacture and that may be conveniently.

andrapidly assembled in the eld. These and other objects and advantages of the` invention as may appear Vhereinafter are `achieved in a well perforating apparatus that is adapted to be passed through small Vdiameter tubing having relatively sharp bends which includes a plurality of longitudinally aligned well perforating units and means linking the units together'to form a chain having a plurality of spaced articulated joints. The articulated joints lend flexibilityto the chain of units permitting it to passthrough sharply curved sections of narrow tubing. The articulatedl joints may include a pivot pin carried by vone-unit received in a complementary hole provided in an adjacent unit. Such joints include means for maintaining the joint elements in an interlocked condition when the units are in alignment While permitting substantial pivotal movement of adjacent units without unlocking of the joint elements. However, when adjacent units are rotated relative to each other through a wide predetermined angle, the locking means is adapted fory quick release whereby the units may be quickly separated. VIn similar manner, the units may be easily and quickly assembled to forma chain.

The perforating units of the invention are so constructed that the shaped charge container has an upstanding arm ,and a depending arm carrying complementary linking elements. The arms are disposed at a substantial angle to each other about the vertical axis yof the unit so that when linked together adjacent units are disposed at an angle to each other'aboutthe vertical axis v of the assembly, whereby the perforation pattern produced thereby is distributed circumferentially as Well as vertically along the well casing. Y

Described in somewhat greater detail, ,the shaped ex plosive charge well perforating apparatus of the inven jet at a substantial angle, the vertical axes of the units being in alignment along the verticalaxis of the well per-V forating apparatus.v The container of each unit khas an upstanding and a depending arm. Means is provided for linking the depending arm of each container to the upstanding arm of the immediately subjacent container for pivotal movement about a point on the vertical axis of More particularly, one of the arms of the container has a terminal planar face containing the vertical axis of the well perforating apparatus and a cylindrical pin is carried by this arm. The pin extends from the terminal face and has its axis intersecting `the vertical axis at right angles. A key is carried by the pin and extends radially from the pin at vright angles to the vertical yaxis and is spaced fromk the terminal face. The other of the arms also has a terminal planar face through which the vertical axis passes and the planes of the terminal faces of the two arms are rotated at a substantial angle to each other about the vertical axis.V The other armhas a cylindrical hole therethrough having its axis intersectingthe vertical axis at right angles. The other arm providesa keyway therethrough communicating with the hole and extending radially from the hole along the vertical axis. The transverse sectional outline of the holeand keyway conrorms in shape to, and s slightly larger than, the transverse sec tenetntine fof the pin: 'and key; g he radirlszefthe keylis; 'ffhel booster: ehar'gecinitiatesl the' mairng I .G pgaidjuce @agiert-lesive liet. fram greater than the 'radius :ef the hole and' the thickness of I the: arm -axialiygofthe hote andfadjaeem Itherein is siiightl'y bei? less' thgan the spacing llsetvjveen the; keyv and erminat y v v v Y areS-flinkedgtogether .to formi ai chain :wherein the pin one unit is received in the hole l of anladjacent; unit; ft r f v fa'cfes ofi the arms ini :abuttment,2 and fthe `key ove'rlies' :the arm -of hei ,adi jacent:r unit opposite its term' al :faceg and is fout off registry' withkeywarfl.'lf 'f2 i .The invention wfill .bey describedw f greater particu@ larity withfthe reference tothe fdr" i i ne parenting l Fig. iis a 'fvertieai sectional viewfthrough anf oil weit n .exemplary l einbogdimercl:` of the; weil perfo-j v stratus 'of th nventic suspended'in thefwell f idg apparatus; and; 5 i 1 'l veasing ire. 'per 1 :lev ,the bottom Lor; the cable? head jan :arrnf 1d l l fde pende; `and :this: arm lsupito'rts agplurality of? interlinkeif, y

' shaped explosive charge; welllp'erforatin'g unitsv designated' by the general reference numeral 15.- The perforating unitsare fired in a manner to be explained more fully hereinafter by a detonating fuse or Primacord 16` disposed adjacent the ends of the shaped charge units. Af-

ixed to the lower end of the Primacord 16 in detonating relation thereto is a detonator or blasting cap 17. A pair of wires 1S, through which igniting current is conductedl to the blasting clap 17, extend from'the blastingrcap and are wound in an upward direction about the chain of` perforating units to enter the cable head 13 in which `the l are connetced to the tiring circuit.

The perforating apparatus is seen partially inside of `the lower end of the tubing 11. Before firing it is `lowered below the bottom of the tubing to apoint oppositethe section of the casing to be perforated.A

Referring to Figs. 2 through 5, the perforating unit of the invention has a charge case 19 closed at its rear end by a cap 2i). The cap ts-tightly in the rear end of the case and the case may be sealed against ingress of bore go uids by means of an O-ring 20a or simil-ar compressible seal interposed between the cap and-the case. i Disposed within the case near the rear end thereof isa charge o f compressed high explosive 21 having a forwardly facing cavity therein lined with `an inert liner 22, preferably of copper or other metal. Stand-off space is provided between the front face of the liner 22 and theronttwall A2.3: a of the charge case to permit the perforating jet to form within the case upon detonation of the charge.

l The cap 20 has a rearwardly projecting cylindrical boss 7g 24 through which is bored a vertically extending fuse passage 25. As shown in Fig. 5, the cap 20 has a booster cavity 26 separated from the fuse passage 25 by aV thin` wall 27' through which de oynating energy `from Vthe Primaord is transmittedto a hoogte: charge in .the cavity. 75

casing shown; v the upstanding f arm y newer/er; tithe.; thickness i dees; 1119 5haya; etc ibe uniform y as minal 'endv ef the; planar face 228i adjacent.I

i lal cyiiednesl. here 3s ferme 'aiplaeicomainefthe@eater line i like! Walsall-a5; @depending erm y hiel; in vthe .embodiment shown, is; of the same leng gi armicontainsthe'een-ter p n the; lower endi of @Meer e ehr' @nella einer ntersects :the center.

armxfnake 'anlanglefof 3:1 explosive' chargefas -best lseenin Fig; v5.v

Figs. 6 and 7 show in enlarged fragmentary mediately Asuperadjacent` shaped charge unit. be seen that the pin 29 is received in the hole 33 with, the key 30 overlying the rear face 35 of the depending arm. With the charges linked in vertical alignment, the

key 30 is 90 out of registry with the keyway 34 andthe

arms

27 and 31 are interlocked, that is to say `the pin.

cannot be moved axially from the hole 33. Htiweven.` the pin 29 is f ree to pivot in the hole 33 through an angle of nearly 90 in a counter-clockwise direction as seen in Fig. without danger vof the-arms becoming disengaged.

rlhe arm 27 may pivot in a clockwise direction asseen` in Fig. 6 more than `90 without danger of disengagement. `The diameter of the hole 13S-s somewhat greater than the diameter of the pin 29 providing a `loose t` ofthe pin in the hole. `It isV also'seen `that the radius of the key 3i) is somewhat greater than the radius of the hole 33 so.`

tothe inner face of the key 30 is somewhat greater than the thickness of the depending arm 31, providing for a free t of the arm 31 between the key and the arm 27. This free fit allows limited rocking movement in the plane of the drawing of the arm 31 inrelation to the arm 27 and thus enhances the exbilityof the assembled perforating gun.

Performing units in .accordance with the invention. are f' ekness,

detail the v v I v manner in which the upstanding arm 27 of one perforatingunit is linked to the depending arm 31 of an im- It will i .readily unlinked vor linked and vwill maintain alignment Aofthe charge units.

seenl in Figs. 2, 4 and 5, the-front face'23 ofthe chargev caseis a segment of aV sphere having its center on the as .will be apparent from a `consideration of Fig. 6. To unlink adjacent units, the arm 27 is rotated counterclockwise .9.0" to swing the key 30y into registry with the keyway 34. The arm 27 may then be disengaged from the arm 31 by simply sliding it to the rear as seen in Pig.

6.v Conversely, adjacent'units arek linked together ,by aligning the key Sil-with thekeyway 34and inserting the pin v29Y inthe hole33. Thereafter the arm 27 Vis rotated..90 in the Vclockwisedirection so that the key ov'erlies the surface 35 of the arm 31. `As seen from Fig. 7, theterminal planar face 32 vof 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.

Although the angular relationship of the key 30 and keyway 34, inthe illustrative embodiment shown, ,requir'es that adjacent linked charge units be-turned 90 from axial alignment to unlockv and disengage them, it

will be understood that other angular relationships may be employedrequiring veither a-somewhat greater or lesser relative rotation for engagement or disengagement of adjacent units. v l' The charge ,unitsr in assembled relationship as shown in Fig. `1 are adapted to be run through narrow Ytubing Withclose clearance. Por this purpose, the charge con- Vtainersare especially dimensioned to provide surfaces that will V slide' through narrow tubing withoutfbinding As center line of the charge unitat its intersection with the horizontal axisof the charge case v19. The boss 24 hasV a sphericalrear face with its Vcenter at thesarne point andvhaving the same-radius as the front face 23.. The

circular rear edge of the charge case 19 lies in this spherey 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 canvslide against the tubing are located on y aV spherical surface having its center -on the Acenter line of the perforating'unit ,and preferably at a point midway -between the axisVof the pin 29 and the axis of the hole 33. Whereas, the

arms

27 and 31 are shown as being of equal length, it vwill be understood that they may have different lengths, if desired, or they may be proportionately longer or shorter than shown in the drawings.

Owing to the hereinbefore described geometry of the charge unit, a linked assembly of such units will readily without the use kof any tools,

. whereby the detonator may be initiated from` the surface of the earth. The assembly is lowered into the wel-1 as;

the hole 33. Ten chargeunits so constructedanddi:

mensioned when linked together to form achain, as shown in Fig. l, were found to run freely in straight Alengthsol tubing having a bore measuring 2" in insidediam'eterand to negotiate bends in such tubing having al radiusof'S- Without binding or becoming lodged therein;` 4

Inpreparing-,or assembling a perforating gun 'inv the eld, acharge 15 is linked to the arm 14 of the cable head 13. The arm 14 has a hole and keyway therethrough, similar to the hole` and-keyway of Athe charge unit here-A inbefore 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 vchain of units. It will be seen that adjacent charge units are dis'- posed at an angle of 120 vto each other about the vertical axis of the assembly. Detonating fuse 16 is threaded through the passageways 25 of the perforating unitsand, wound about the assembly in helical disposition as shown.' The lower end of the fuse 16 is'equipped with adet'onator 17, the wires 18'of which are led upwardly to the cable head in which they are connected to the tiring circuit shown in Fig. l to the desired level.A The firing circuit is energized.' The blasting ycap 17 detonates the Primacord 16 which practically simultaneously detonates the individual perforating units 15 tov perforate the casing and surrounding earth formation. The charge unitsy 15 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 ofthe charge container that make sliding contact with the bore of the tubing. These faces and edges are termed the skating faces of the charger container, since they slide or V'skate alongthe bore of the tubing. Such an assembly of unitsis'free to rotate on its Yvertical axis within the confines of closelytting straight tubing without substantial lateralfdisplacement of any ofthe units from alignment with the vertical axis of the assembly and without becoming lodged in theV tubing as it is lowered therethrough. Moreover, the articulated joints linking adjacent units together and the angular phasing of such joints v about the vertical axis of the assembly allow the assemvbly. 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 accompanying 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 V11i/i6, and the center of the spherical surface was located on the center line of the charge unit midway between the pin 29 and are frangible and are broken into small fragments which Afall -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 yfiring for re-use. j A l Y 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 thefsame 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 Yholes 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 selected for use may be broken off and discarded. A

From the foregoing description of a typicalembodiment 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 contemplatedthat the` detonating fuse 16 ymay be red from the top instead ofV from the bottom by merely changing the position of the blasting cap 17. It is also contemplated Vthat the lower end of the assembly may be provided with a suitable bull plug if desired. Moreover, blank interval linking members may be provided between adjacent charge units to increase charge spacing. `Such blank interval members are similar to the charge units, insofar as concernsfthe complementary linking elements, but are simply flat bars of metal carrying no explosive charge. It is also contemplated that the perforating units need notembody 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 to each otherVany 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.

I claim:

l. Shaped explosive charge well perforating apparatus adapted to be passed through small diameter tubing having relatively sharp bendscomprising: 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 @sans of said arms having a terminal planar face "containingthe vertical axis of said unit; a cylindrical pin Afixed to said one arm, said pin extending from said terminal face and having its axis intersecting the vertical axis of said unit at right angles; a key carried by said pin, said key extending radially from said pin at right angles to the vertical axis of said unit and being spaced from said terminal face; the other of said arms having a terminal planar face containing the vertical axis `of said unit, the planes of said terminal faces being rotated at a substantial angle to each other about the vertical axis of said unit, said other arm providing a cylindrical hole therethrough having its axis intersecting the vertical axis of said unit at right angles and providing a keyway therethrough communicatingwith said hole and extending radially from said hole along the vertical axis of said unit, thetransverse sectional outlines of said hole and keyway conforming in shape'to and being slightly larger than the transverse sectional outline of said pin and key, the radius of said key being greater than the radius of saidhole, and the thickness of said other arm axially of said hole and adjacent thereto being `slightly less than the spacing between said key and theterrninal face of said one arm; said perforating units being linked together to form a chain wherein the pin on one of thearms of one of said units is received in the hole in the other of the arms -of an adjacentV unit, the terminal faces of said arms are in abutment, and said key overlies the arm, of said adjacent unit opposite its terminal face and is out of registry with the keyway, each unit being readily detachable` from an adjacent unit by rotating the unitabout the axis of the pin to align the key with theV keyway and Withdrawing the pin from the hole. v

2. A shaped explosive charge Well perforating unit coinprising: a pressure resistant, frangible, sealed container having a shapedexplosive charge therein adapted upon detonation to project an explosive jet outwardly through a wall-of the container, said unit having a vertical axis intersecting the axis of the explosive jet at a substantial angle; a first arm carried by said container and being the sole arm extending tbereabove andhaving a terminal planar `face containing the vertical axis of said unit; a cylindrical pin xed to said arm, said pin extending perpendicularly from said terminal face andghaving its axis intersecting the vertical axis of said unit; and a key carried by said pin, said key extending radiallyfromjsaidpin at right angles to the-vertical axis of said unit and being spaced from said terminal face; a second arm carried by said container and being the sole arm extending therebelow and having a terminal planar face containing the vertical axis of said unit, the planes of said terminal faces being rotated at a substantial angle to each other about the vertical axis or" said unit, said second arm providing a cylindrical hole therethrough extending perpendicularly from the terminal face thereof and having its axis intersecting the vertical axis of said unit, said seconda-rm providing a keyway therethrough communicating with said hole and extending radially from said hole along the vertical axis of said unit, y

the transverse sectional outline of said hole and keyway conforming in shape to and being slightly larger than the transverse sectional outline of said pin and key, the

radius of lsaidkey. beingV greater than the radius of said hole, and the thickness of said'second arm axially of said hole `and adjacent thereto being slightly less thanthe spacing between said key and the terminal face of said` first arm, a plurality of such unitsbeing interconnectible to form a chain by aligning the pin and key of one unit with the hole and keyway of another unit, inserting the pin into the hole to bring opposite terminal planar faces into abutment, and turning the units about the axis of the pin to align the axes of the units, thus locking the` units together. p p f y 3. A shaped explosive charge Well perforating unit comprising: a pressure resistant, frangible, sealed container having a shaped explosive charge therein adapt` ed upon detonation to project an explosive jet outwardly through a wall of the container, said unit having a vertical axis intersecting, the axis of the explosive jet at a substantial angle; a first arm carried by said container and beingthe sole arm extending tbereabove and `having a terminal planar face containing the vertical axis of said unit; a cylindrical pin ixed to said arm, said pin extending perpendicularly from said terminal face and having its axis intersecting the vertical axis of said unit; and a key carried by said pin, said key extendingmradially from said pin `and being spaced fromsaid terminal face; a second arm carried bysaid container and being thesole arm extending therebelow and having a ,terminall planar face containing the vertical axis of said unit, the planes of said terminal faces being rotated at a substantial angle to` each other about the vertical axis of saidunit, said second arm providing a cylindrical holetherethrough extending perpendi-` cularly from the terminal face thereof and having it `axis intersecting thevertical axis of said Vunit,`said second arm providing a keyway, therethrough communicating with said hole and extending radially from said hole at an angle to the vertical axis of the unit which differs substantially from the angle which said key makes with the vertical axis, thewtransverse sectional outline of said hole and keyway` conforming in shape to and being slightly larger than `the transverse sectional `outline of said pin and key, the radius of the said key being greater than the radius of said hole, and the thickness of said second arm axially of said hole and adjacent thereto being slightly less than the spacing between said key and the terminal face of said iirst arm, a plurality of such units being interconnectible to form a chain by aligning the pin and key of one unit with the hole and keyway of another unit, inserting the pin into the hole to bring opposite terminal planar faces into abutment, and turning the units about the axis of the pin to align the axes of the units, thus locking the units together.

References Cited inthe file of this patent `UNITED STATES PATENTS `1,598,293 Luck Aug. 31, 1926 2,026,061 Prikel Dec,` 31, 1935 2,151,837 Burke Mar. 28, 1939 2,616,370 Foster Nov. 4, 1952 `2,633,329 Le Bus Mar. 31, 1953 2,799,224 Long ...Q July 16, 1957 2,853,944` Robertson Sept. 30, 1958 FOREIGN PATENTS 701,074 Great Britain Dec. 16, 1953