US2108172A - Casing perforator - Google Patents

Description

F 1 c. B. MARGRAVE v 2,108,172

CAS ING PERFORATOR Filed Jan. 11, 1957 2 Sheets-Sheet l Z22 f ezz i or. '18 Char/es B. Morgm ve HZ iorneys.

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Feb. 15 1938. c. B. MARGRAVE 2,108,172

CASING PERFORATOR Filed Jan. 11, 1937 2 Sheets-Shem. '2

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[221/622 tor C bar/e5 B. Margra l/ Fatented Feb. 15, 193% arcane CASING 'rnnr'ona'roa Charles B. ltiiargrave, Los Angeles, (Calif; assignor oi one-half to Albert ll. liiireslow, Los Angeles,

Calif.

Application January 111, 1193?, Serial No. 120,026

llli Claims.

My invention pertains to a perforator for perforating well casing such as the casing of oil wells and provides a type of perforator which gives a clean cut at the perforation and forces the slit metal of the casing outwardly at the perforation developing a slight fin at the top of the perforation which restricts the entrance of sand with oil into the casing. Another feature of my invention is that the perforator which has perforating cutters causes these cutters to have a sliding movement transverse to the axis of the casing and in which the perforating cutters or cutter tools thus have a sliding 'motion radially of the casing and as two tools are employed, these are diametrically opposite. Another'feature of my invention is developing a force to force the tools through the casing by a toggle action, this being produced by a slight lowering of a drill string or the like to force the perforator tools outwardly, 20 these being supported by a portion of a string of drill pipe or similar tools resting on the bottom of the well and extending upwardly to the desired position in which it is desired to perforate the casing.

Considered in more detail, a further object and feature of my invention is in the construction of toggle actuated cutter tools operating in diametrically opposite slots, each of which is connected to toggle links, these being pivoted to a common head and such head being slidably arranged in a guide block. When this guide block is connected to the upper portion of the string of drill pipe, the assembly may be lowered into the well and when the bottom of the string below the blocks 35 supporting the cutting tools contacts the bottom of the well, the further slight lowering of the drill string due to the weight causes the movable head having the toggle links to develop a further downward movement, the links thus pressing the cutter tools outwardly diametrically opposite and thus perforating the casing. A further detail feature of my invention is in the shape of the cutter tools which preferably have a fiat or straight bottom edge, an upwardly and inwardly sloping perforating surface with slightly beveled side edges. This causes the cutter tool to make a clean cut at the bottom of the perforation, this being a sheer cut on the casing. A sheer'cut is also given at the sides of the perforation so that an upper protruding lip is bent outwardly at the top of the perforation. This lip tends to prevent sand settling through the opening of the perforation into the casing. Another characteristic of the type of perforator used coupled with the sliding motion is that the perforator may be used to (m. Mil-4B4) crack cement which may be on the outside of the casing. This is an advantage as it sometimes happens that in cementing oil a water bearing strata that the cement will also cut off a portion of the oil bearing sands. With my type of perforators the casing may not only be perforated but also the cement on the outside cracked to permit inflow of oil.

My invention is illustrated in connection with the accompanying drawings, in which:

Fig. l is a vertical section through my invention taken on the line l--l of Fig. 3 in the direction of the arrows showing the perforator cutters and toggle links in elevation and also the plug and rod to which these are connected shown in elevation. In Fig. 1 the cutters are retracted.

Fig. 2 is a section similar to Fig. 1 with the cutters forced outwardly by the downward movement of the toggle links.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 2 taken in the direction of the arrows.

Fig. 4 is a detail vertical section on the line 44 of Fig. 2 in the direction of the arrows showing one of the cutters and the cutter guide opening.

Fig. 5 is a horizontal section on the line 5-5 of Fig. 2 on a reduced scale.

Fig. 6 is a detail plan of one of the perforating cutters removed from the assembly.

In my invention a toggle guide block assembly designated by the numeral ll consists of a lower block I2 whichhas a flat upper surface I3 transverse to the axis of the tool, the side wall M is cylindrical merging by a rounded corner Hi to a fiat bottom surface l6 from which an integral solid rod il extends downwardly. The upper block member is heavy and rests on the fiat surface 13 of the lower block. This however has two diametrically opposite guide slots 22 defined by the two opposite vertical edges 23, the top edge 2i and the surface iii of the lower block forming the bottom wall of the guide opening.

This block is also cylindrical as to its side wall 25 and has rounded corners 25 merging with the fiat top surface 271. Centrally positioned in the upper block there is a large circular bore 28 and below this there are diverging recesses 29 having a sloping upper surface, 30 merging with the upper surface M of the guide openings 22, this slope being to accommodate the toggle lengths hereinunder detailed. These recesses are considerably wider in a transverse measurement indicated at (ii in Fig. 3 to accommodate the toggle links as hereinunder detailed. The two blocks are held together by utilizing a strong and heavy ring 32 which rests on the fiat top 21 of the upper block. This ring has a peripheral wall 33 preferably slightly smaller than the diameter of the upper block 28 as to its cylindrical wall 25 and has a central opening 34 which is smaller in diameter than the bore 28.

A heavy cylindrical plug 40 having an integral rod 4| preferably cylindrical is part of the toggle actuating assembly, the plug being located in the large bore 28, this plug having an upper shoulder 42 engaging underneath the heavy ring 32. This ring and the upper and lower blocks are securely bolted together by a series of, longitudinal bolts 43. Thus by suspending the rod 4| the plug40 may engage underneath the ring 32 and suspend the whole block assembly H and a portion of a drill string as hereinunder described, secured to the lower end of the solid rod l1.

The plug 40 has a recess 44 from its undersurface 45 and in this is fitted the upper end of the toggle plate 46. This plate is rectangular in horizontal section as indicated in Fig. 3 and has a shoulder 41 bearing on the undersurface 45, this plate being secured by a pin 48 or the like extending through the plug 40 and through an opening in the portion of the plate inserted in the recess 44.

The toggle assembly 50 has two pair of parallel toggle links 5|. The-upper end 52 of each pair is pivoted to the toggle plate 46 by substantial toggle pins 53. The lower ends 54 are pivoted also by substantial pivot pins 55 to the perforating cutting tools 56. Such perforating tools have a flat lower surface 51, parallel sides 58 and a flat top 59. There is a sloping cutting end 60 with a sharp forward cutting point 6|. The two side edges of the sloping face of the cutter are slightly beveled as indicated at 62 and also adjacent the sharp edge 6| there may also be a slight bevel 63.

The manner of assembling the tool in a string of drill pipe may be in any suitable way, the manner illustrated showing an upper sub 10, the upper end of the solid rod 4| being threaded therein as indicated at 1|, these being tight threads not intended to unscrew in disconnecting stands of the drill string. This sub is shown as having a taper threaded box 12 to which a pin of a tool joint coupling may be connected, this forming part of the drill string with the tool inserted in the string. As it is usually necessary to perforate the casing at some distance above the bottom of the well, the lower solid rod H is shown as threaded into a lower sub 15, this having a tight fitting threaded section l6. This sub may also have a pin on its lower end for connecting to the lower part of the drill string by a tool joint coupling and below this there may be a further portion of the drill string indicated at 11. This is shown as resting on the bottom of the well hole indicated at 18. The bore of the hole is indicated at 19 and the casing at 80. It sometimes occurs that outside of the casing there is a body of cement indicated at 8|, and although the cement is usually 'for the purpose of cutting off water from the well,

sometimes this cement is found to be in an oil bearing strata.

In the operation of my invention it will be understood that a survey of the well has made it known what locality of the casing is to be perforated, therefore the drill string is made up with the perforating tool in the proper place so that the lower end of the string may rest on the bottom of the hole. In lowering, the plug 40 engages the ring 32 and carries the weight of all of the string below the solid rod 4|. While the string is being lowered the toggle links are in the upper position and the tools are retracted as shown in Fig. 1.

- When the lower end of the drill string as indicated at H contacts the bottom of the hole and the upper part of the string is lowered, the weight proximately a straight out, this causing a lip indicated at 82 to be forced outwardly above the perforation. Such lip tends to restrict the flow of sand into the casing. The perforating cutters are also operative to crack any cementing wall on the outside of the casing and thus allow a flow of oil through such cement.

Various changes may be made in the details of the construction without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. A casing perforator comprising in combination a substantial block assembly having diametrically opposite straight transverse guide openings and a central bore connected thereto, perforators rectilineally slidably mounted in the openings, a plug slidably mounted in the bore, toggle links, means connecting the toggle links between the plug and the perforators, a supporting means connected to .the lower end of the block assembly for supporting the block in a desired position in a well casing, means attached to the plug for connection to a string of drill pipe for raising and lowering the plug whereby when the plug is elevated the perforators are retracted and when the plug is lowered. said perforators are forced outwardly to perforate the casing.

2. A casing perforator comprising in combination a block assembly having a lower block and an upper block, said blocks having contiguous horizontal surfaces with a pair of diametrically ing the upper ends of the toggle links to the said plug, a supporting means connected to the lower block for retaining the block assembly in the desired position in a well casing, means connected to the plug for attachment to a string of drill pipe whereby the block assembly may be lowered in a casing and when the supporting means supports the block assembly in the desired position the continued downward movement of the plug forces the perforators outwardly laterally to perforate the casing.

3. A casing perforator as claimed in claim. 2, the supporting means comprising a rod connected to the lower block, a sub connected thereto, said sub being adapted to engage the bottom of the well hole.

4. A casing perforator comprising in combination a block assembly having a lower block with a horizontal upper surface, an upper block with a complementary surface and a pair of diametrically opposite straight radial guide openings exopenings and bearing on the upper surface of the lower block, toggle links connected to the perforators, means pivotally connecting the upper ends of the toggle links to the said plug, the plugv having a shoulder engaging the under side of the said ring, means for attaching the plug to a string of drill pipe, a supporting means connected to the lower block for supporting the block assembly in a desired position in a well casing, the said block assembly and the supporting means being adapted to be lowered into a well suspended from the plug and with the perforators retracted, a downward movement of the plug when the-block assembly is held stationary being adapted to force the perforators diametrically outwardly to perforate the casing. a

5. A casing perforator as claimed in claim 4, theperforators having a flat lower surface terminat'ng in a horizontal outer cutting edge, an upwardly sloping. cutting end from the cutting edges whereby in perforating the casing an outwardly projected lip is. formedabove the perforation.

6. A casing perforator as claimed in claim 4, the means connecting the toggle links to the plug comprising a toggle plate connected to the lower end of the plug, the upper ends of the toggle links being pivotally connected to the said plate.

7. A casing perforator comprising in combination a block assembly having a lower block with a horizontal upper surface, a rod projecting downwardly and having means for connection to a lower sub, an upperblock having a flatJower surface contacting the upper surface of the lower I block, the upper block having'diametrically opposite straight radial guide openings forming two uide slots defined by opposite vertical sides, a horizontal top and the upper surface of the lower block, the upper block having a central bore connecting with the said slots, aring on the top of the upper block and having an opening smaller" than the said bore, bolts connecting the two blocks and the ring, a plug slidably mounted in the .said

bore and having-a toggle plate connected thereto at the bottom, a pair of toggle links pivotally connected to said plate, a pair of perforators in the said slots and pivotally connected to the lower end of the toggle links, means connecting the plug and adapted for attachment to the lower end of a; string of drill pipe whereby the assembly of the blocks and thelower sub may be lowered into awell, the ring engaging the said plug and thereby retracting the perforators, the said sub on engaging the bottom of the well hole forming a solid support for the block assembly whereby the continued downward movement of the plug forces the perforators rectilineally outwardly to perforate the casing.

8. A casing perforator as claimed in claim 7, I

the perforators being rectangular in vertical cross-section and having a flat lower surface with a horizontal. outside cutting edge and upwardly sloping cutting ends, the said ends on each side having a slight bevel whereby on perforating a casing a clean horizontal sheer cut is formed at the bottom of the perforation and lips are out-- wardly bent at the upper part of the perforation.

9. A casing perforator comprising in combination a block assembly having a lower block with a horizontal upper surface, an upper block having a complementary lower horizontal surface with a pair of diametrical straight radial .slots in its lower surface defining with the upper surface of the lower block straight radial guide openings rectangular in cross section, the upper block having enlargements at the inner end of said slots and a central circular bore connecting to said enlargements, a ring on the upper end of the upper block, bolts through the ring and the two blocks, a cylindrical plug mounted in the bore and having an upper shoulder engaging the ring, perforators rectangular in cross section slidably rectilineally transversly in the said slots, toggle links having their lower ends pivotally connected to the inner ends of the perforators, means pivotally connecting the upper ends of the toggle links to the said plug, the lowerblock having a solid lower rod of much smaller diameter than .the block extending downwardly and a lower sub connected to said lower rod, the plug having a solid upper rod extending upwardly through the ring and having means for connection to astring of drill pipe whereby the assembly may be lowered into a well, the shoulder of the plug engaging the said ring and when the lower sub contacts the bottom of the well hole the continued downward movementof the plug forces the perforators outwardly.

' 10. A casing perforator as claimed inclaim 9,

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