US3115932A - Apparatus for consolidating incompetent subterranean formations - Google Patents

Description

Dec. 31, 1963 APPARATUS FOR CONSOLIDATING INCOMPETENT SUBTERRANEAN FORMATIONS Filed Oct. 5, 1960 J. J. REYNOLDS 4 Sheets-Sheet 1 I I 4' |o- I2 I I! 52 55 s2 s3 5 I -51 5e -53 I l64 6| I g g [65 I 456 L 7 nl i 66 'i 79 69 Ill] 1' 82 85 so 74 l I 83- i 4 as I l 73 SI q 92 INVENTOR.

JACK J. REYNOLDS A TTORNE Y Dec. 31, 1963 J. J. REYNOLDS APPARATUS FOR CONSOLIDATING INCOMPETENT SUBTERRANEAN FORMATIONS 4 Sheets-Sheet 2 Filed 001). 5, 1960 IN VEN TOR.

JACK J. REYNOLDS A TTORNE Y Dec. 31, 1963 J. J. REYNOLDS 3,115,932

APPARATUS FOR CQNSOLIDATING INCOMPETENT SUBTERRANEAN FORMATIONS Filed 001;. 5, 1960 4 Sheets-Sheet 3 L g n INVENTOR.

JACK J. REYNOLDS ATTORNEY Dec. 31, 1963 J. J. REYNOLDS 3,115,932

APPARATUS FOR cousounmmc INCOMPETENT SUBTERRANEAN FORMATIONS -Filed Oct. 5, 1960 4 Sheets-Sheet 4 FIG. 6 FIG. 7

INVEN TOR.

JACK J. REYNOLDS A TTORNE Y United States Patent Ofiice Patented Dec. 31, 1963 3,115,932 APPARATUS FOR CGNSOLIDATING INCQMEE- TENT SUBTERRANEAN FGRMATKUNS Jack J. Reynolds, Houston, Tex., assignor to Continental Oil Company, Ponca Qity, Okla, a corporation of Delaware Filed st. 5, 1960, Ser. No. 60,636 8 Claims. (til. 166-551) The present invention relates to a new and improved apparatus for completing a well traversing an unconsolidated subterranean formation, and more particularly is directed to an apparatus for isolating, perforating, and injecting a suitable consolidating agent through a casing and into the adjacent subterranean formation to consolidate said formation at each interval of perforation.

Production of hydrocarbons from an incompetent subterranean formation which is unconsolidated, due to the presence of sand or sandstone in a loose or friable condition, normally results in the production of nudesirable quantities of sand particles. In order to produce any cased well it is necessary to establish communication between the hydrocarbon-bearing formation and the production equipment within the annulus of the casing, the most common means being a perforation of the casing at the desired intervals, which also allows the production of any loose sand therein. These sand particles are produced through the casing perforations either to the surface causing severe erosion and corrosion in the equipment, or become an accumulation of sand at the bottom of the well bore choking the production therefrom.

The problem of controlling sand production has been approached in several ways, such as screens, liners, etc, but the most elfective manner is the introduction of a bonding agent into the offending formation wherein the sand production is generated. Prior art teachings disclose the necessity of performing several different operations in order to achieve the perforation, injection, squeezing, displacement and setting, if necessary, to obtain a satisfactorily bonded formation. (These methods fail to obtain sufiicient bonding in each interval of the formation perforated which frequently results in a more deleterious effect by concentrating the total sand production through a limited number of perforations, thereby causing a complete casing or tubing failure.

Briefly, the present invention is an apparatus comprising a tubular member containing several piston assemblies dividing the upper portion into chambers, a propellant to energize said assemblies and activate a packer means and perforator to isolate, perforate, and inject a bonding agent into the formation, together with suitable means for elieoting removal of the apparatus upon completion of the operation, or in the event the perforation is not elfected.

An object of the present invention is to provide an improved apparatus for the completion of incompetent subterranean formations traversed by a cased well bore.

Another object of the present invention is to provide an improved apparatus for completing the well bore and formation for product-ion by a single apparatus and operation.

A further object of the present invention is to provide an improved apparatus which will effectively consolidate the formation at each perforated interval.

-A still further object of the present invention is to provide an improved apparatus which overcomes the disadvantages and unsuccessfulness of the prior art.

Other objects and advantages of the invention will be evident from the following detailed description, when read in conjunction with the accompanying drawings which illustrate the invention.

In the drawings:

FIGURE 1 is a vertical sectional view of the upper portion of the apparatus with the supporting cable.

FIGURE 2 is a vertical sectional view of the intermediate portion of the apparatus which is a continuation of FIGURE 1.

FIGURE 3 is a vertical sectional view of the lower portion of the apparatus which is a continuation of FIG- URE 2.

FIGURES 4-7 are schematic representations of the apparatus in the various phases of operation.

Referring to the drawings which illustrate a single embodiment of the invention, and particularly FIGURE 1, reference character It designates a section of casing within a subterranean well bore. This invention is a cylindrical apparatus generally designated as 11 which is suspended in a W611 bore annulus 12 by a cable 13 which supports the apparatus and provides the conduit for a suitable conductor means 14 extending from the surface to the apparatus. The upper end of cable 13 is ordinarily connected to a suitable firing mechanism or instrument truck (not shown) at the surface for actuating the apparatus, and the lower end is suitably connected and wired to the apparatus 11.

The apparatus 11 comprises an upper head 15 which is adapted to receive cable 13 through a longitudinally extending passage .16 with a threaded means 16a adapted to restrain cable 13, and has a longitudinally extending bore 17 adapted to be a propellant chamber. Head 15 is secured to an upper cylindrical member 18 by a threaded means 19 and has a circumferential groove 2t) for a sealing ring 21. A propellant 22 is adapted to receive the conductor means 14 which is connected to a detonator 23, and is supported by a gas choke assembly 24. The gask choke assembly is threadably connected to head 15 by a threaded means 25 to complete a gas tight propellant chamber within bore '17, except for a shaped choke conduit 26.

Cylindrical member 18 contains a floating piston assembly 27 below choke assembly 24 establishing a chamber 28 wherein a sealant liquid 29 overlays the assembly 27. This assembly has a slidable power piston 30 having a circumferential groove 31 for a sealing ring 32, and a central aperture 33 adapted to receive a shaped gas bleed valve 34 having a shoulder 35. The valve is attached to a slidable sleeve 36 having vertical ports 37 by a threaded means 38, and the valve and sleeve are positioned by a spring 39 in contact with piston 30 and sleeve 36 above a chamber 40 cylindrical member 18.

Referring to FIGURE 2 of the drawings, a continuation of FIGURE 1 showing the intermediate portion of apparatus 11, cylindrical member '18 contains a floating piston assembly 41 below assembly 27 establishing the lower limits of chamber 46. Assembly 41 comprises a floating piston housing 42 having a central aperture 43 and a shoulder 44, with a circumferential groove 45 for a sealing ring as. Housing 42 has vertical ports 47, and a central bore 48 to receive a valve 49 having a shoulder 50, said valve being positioned by a spring 51 adapted to allow passage of fluid only in the direction of a chamber 52 within cylindrical member 18.

Member 18 contains another floating piston assembly 53 below assembly 41 establishing the lower limits of chamber 52. Assembly 53 comprises a floating piston housing 54 having a central aperture 55 and a shoulder 56, with -a circumferential groove 57 for a sealing ring 58. Housing 54 has a series of horizontal pressure exit ports 59, vertical ports 60, and a central bore 61 to receive a valve 62 having a shoulder 63, said valve being positioned by a spring 64 adapted to allow passage of fluid only in the direction of a chamber 65 within cylindrical member 13.

Member 18 has horizontal pressure exit ports 66 covered by a slidable collar 67 having circumferential grooves 63 and 69 for sealing rings 70 and 71 respectively, to maintain chamber d in a sealed condition While the collar is in position, said collar being positioned by shear pins 72. An extended portion of cylindrical housing 18 forms a skirt 73 adapted to receive a hydraulic firing head assembly 74 and a lower head 75 rigidly attached thereto by a threaded means 76. Firing head assembly 74 has a longitudinally extending open-ended chamber 77 adapted to receive a differential pressure switch 78 which is positioned by a shear pin 79 and sealed by sealing rings 89 and 81. The chamber 77 of assembly 74 is horizontally traversed by ports 82 in communication with chamber 65, and a horizontal port 83 in communication with the well bore annulus 12 surrounding housing 13 with assembly 74- having a circumferential recess 84 with adjacent sealing rings and 86. Extending through assembly 74 and lower head 75 are L-shaped bores 87, a vertical portion of which appears in FIGURE 2.

The lower head 75 has a bore 88 extending through the upper portion thereof to accommodate a conventional firing mechanism 89 having a contact 90 to receive the switch 78 and activate a conductor 91 extending through a passage 92 to a perforating means.

Referring to FIGURE 3 of the drawings, a continuation of FIGURE 2 showing the lower portion of apparatus lll, lower head 75 contains L-shaped bores 37 in communication with a flexible elastic packer 93 attached to skirt 73 by a connecting means 5 4. Head 75 has a laterally extending open-ended chamber 95 adapted to receive a perforating means 96 rigidly positioned by a threaded means 97. The perforator 96 is the usual cartridge unit, each unit having a barrel 117, a projectile 98, a propellant 99, and a detonator we connected to conductor 91, etc.

Head 75 has a latitudinal passage 1W1 communicating with the packer 93 which intersects a longitudinal passage 1492 in communication with a floating piston assembly 163 in an open-ended chamber N4 of head 7'5 having a sealing ring 116. Passage M52 extends through a bore MP5 of piston assembly 1e73, wherein a flanged plug 1% is affixed by a threaded means 107 in order that a circular rupture disk 1'08 effects a barrier to the flow of liquid through bore 192. Plug 11%, and thusly piston assembly M53, is supported by a spring 153? which is in communication with a lower conical housing 116). A flanged collar 111 is aifixed by a threaded means 112 to restrict downward movement of piston 163. Housing 1N supports the lower edge of packer 93 by a connecting means 114 and is attached to head 75 by shear pins 113 while having latitudinal ports M5 in communication with the casing annulus 12.

Referring to FIGURE 4, assuming the apparatus lit to be positioned within casing It at the desired location adjacent to an incompetent hydrocarbon-bearing formation and that the apparatus is prepared for use by having chamber 28 partially filled with sealant liquid such as viscous oil to prevent the escape of gas pressures generated by propellant 22, chamber filled with a flushing fluid such as kerosene or diesel oil, chamber 52 filled with a sand consolidating fluid such as a liquid plastic, and chamber 65 filled with a purge fluid such as kerosene or diesel oil, the apparatus is then activated from the surface through cable 13. The activating impulse is transmitted through conducting means 14 to the detonator 23 which ignites the propellant 22 within bore 17 of upper head 15 whereby propellant gases are generated and directed through the choke conduit 26 of assembly 24. Upon entering chamber 2% these gases rapidly compress sufliciently to exert substantial pressure on piston 34) through sealant liquid 2% to force piston assembly 27 downwardly, which simultaneously forces piston assemblies 41 and 53 downwardly also as the spring means 39, 51, and 64 are preset to retain the respective valves in closed position during this stage of normal operations, though each spring has successively greater tension than any lower spring means. This is accomplished because the fluids in chambers 40, 52, and 65 are relatively incompressable, and the spring means prevent valves 49 and 62 from opening to allow fluid to pass through piston housings 42 and 54 respectively.

The purge fluid in chamber 65 is forced through bores 87 in assembly 74 and head 75 against the interior wall of packer means 93 causing it to forceably expand against the interior casing Ill, thereby setting apparatus 11 to isolate a portion of annulus 12. As the packer has been expanded the purge fluid has also entered lateral ports 52, but shear pin 79 is of a previously selected strength suflicient to resist shearing until the packer has sufficiently set the apparatus within the casing. After expansion of the packer means, increased pressure is transmitted to the upper surface of switch 78 while the lower surface separated by ring 89 is subjected only to the pressure of the fluid within the well bore annulus as it enters chamber 77 through port 83. This increased pressure exerted through ports 82 rapidly exceeds the strength of shear pin 79 which releases switch 73 allowing the fluid under pressure entering ports 82 to force switch 78 downwardly through chamber 77 of assembly 74. Switch 78 moves into chamber 88 communicating with contact to activate firing mechanism 89 which transmits an impulse through conductor 91 within passage 92 of head 75 to the detonator ltltl of the perforating means 5'6 within chamber 5 of head 75. The detonator ignites propellant 99 discharging projectile 98 from the perforating means through the purge fluid behind packer 93, the packer, and casing 10, into the formation thereby perforating the formation adjacent the apparatus.

Referring to FIGURE 5, the perforation through the packer means relieves immediately the pressure barrier previously restraining further downward movement of assemblies 27, 41, and 53, thereby causing the remainder of the purge fluid to be discharged from chamber 65, until assembly 53 rests against slidable collar 67. Spring 64, having less strength than springs and 51, is overcome by the continuing gas pressure of the propellant 22 which causes valve 62 within housing 54 to open allowing the sand consolidating fluid within chamber 52 to pass through housing 54 and ports 60, through bores 87, and into the formation whereafter assembly 41 rests against assembly 53, and upon collar 67. Continuing gas pressure from chamber 28 forces spring 51, having less strength than spring 3% to be overcome causing valve 9 within housing 4-2 to open allowing the flushing fluid within chamber 4d to pass through housing &2 and ports 47, through bores 87 and into the formation whereafter assembly 27 rests against assembly 41 and upon collar 67.

Referring to FIGURE 6, all of the sand consolidating fluid has been displaced into the purged formation, but the pressure generated by propellant 22 continues to increase thereby driving assembly 27 to displace the flushing fluid within chamber 40 into the formation. Referring to FIGURE 7, the pressure is continued until assembly 27 rests against assemblies 41 and 53 and slidable collar 67 which is held in place by shear pins 72. Spring 39, having greater strength than shear pins '72, allows the pressure upon assembly 27 to be applied to shear pins causing sliding collar 67 to be lowered, opening up ports 66 in cylindrical member 18. Thereupon all pressure generated by the propellant acts upon the upper surface of piston 30 and valve 34, causing spring 39 to be compressed as piston 30 is forced against sleeve 36 opening central aperture 33 to chamber 28, allowing sealant liquid 29 and gases within chamber 28 to move through ports 37. All fluids in the upper chambers 23, 40, 52, and 65 flow through aperture 33 and ports 37, aperture 43 and ports 47, aperture 55 and into the annulus 12 through lateral ports 59 in housing 54 thereby venting all excess pressures, and concurrently releasing pressure on packer 93 to collapse it, enabling the apparatus to be removed from the well bore.

During the lowering of the apparatus into the well bore the liquids in the chambers are subject to expansion as the temperatures become increased at the lower depths of the well bore. As the liquids expand a portion of the purge fluid is displaced through bores 87 and behind packer 93 where the fluid enters passages 101 and 102 in head 75 and passage 105 in floating piston assembly 103 where it contacts rupture disk 108 supported by plug 106. Contact with the disk exerts pressure to lower piston 103 in chamber 104 by compressing a spring 109 having less tension than shear pin 79 to allow expansion of the fluids until piston 103 rests upon flanged collar 111 threadably attached to head 75.

In the event that the apparatus is lowered into position and actuated without obtaining a suficient perforation in the above set forth sequence of operational events, the fluids are conducted through the passages 101 and 102 as in the preceding paragraph. Malfunction of the perforating means forceably displaces the pressured liquids into these passages whereby disk 108 is ruptured, by pressures less than that necessary to rupture or wedge the housing 18 in the casing, thus allowing the fluids to flow through the lower portion of pasage 102 into conical housing 110 and out of a plurality of ports 115 into the well bore annulus. This will enable the instrument to be recovered and reused with minimum expense and effort.

In the event a malfunction should occur after a success ful formation isolation operation, such as failure of the packer to deflate or failure to rupture disk 108, tension can be applied to cable 13 to cause shear pins 113 to give way allowing removal of the apparatus, except for the conical housing 110 and the packer 93 which can be removed by drilling to clear the well bore.

Although a specific embodiment of the invention has been described, it should be understood that the invention is not limited thereto, since many variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. An apparatus for consolidating an incompetent subterranean formation traversed by a cased well bore comprising an elongated cylindrical member having an upper and lower end; an upper head rigidly attached to the upper end of the cylindrical member with a bore extending from the lower portion thereof and a passage through the upper portion thereof in communication therewith; a cable adapted to support said apparatus and containing a conductor extending through said passage and attaching to the upper head by a suitable means to isolate said passage and bore of the upper head; a gas pressure generating means disposed in the bore of the upper head; a detonating means communicating with said gas pressure generating means and attached to the conductor contained by said cable; a choke assembly mounted in the lower portion of the bore of the lower head to retain said gas pressure generating means and having conduits extending between said bore and the interior of the cylindrical member; at least a first, second, and third piston assemblies slidably mounted within the cylindrical member between said choke assembly and the lower end thereof; a pressure operated valve mounted in each of said piston assemblies adapted to open on response to pressure of the gas pressure generating means to permit fluid flow therethrough toward the lower end of the cylindrical member; a lower head rigidly attached to the lower end of the cylindrical member having a bore extending from the upper portion thereof; an inflatable packing means circumferentially disposed about said lower head; fluid communication means extending through the lower head from the cylindrical member to said packing means; at least one perforating means within said lower head adjacent and in communication with said packing means; and a pressure operated firing means within the bore of the lower head in communication with the interior of the cylindrical member and said perforating means.

2. In an apparatus for consolidating an incompetent subterranean formation traversed by a cased well bore comprising an elongated cylindrical member having first and second ends; an upper head connected to said first end with a bore extending therein from the cylindrical member and a passage therethrough communicating with said bore; a cable extending through the passage of the upper head adapted to support said apparatus and containing a conductor; a cable attaching means in the upper portion of said upper head connecting said cable to the upper head isolating said passage and head; gas pres sure generating means disposedin the bore of the upper head; a detonating means communicating with said gas pressure generating means and attached to the conductor contained by said cable; a choke assembly mounted in the lower portion of the bore of the lower head to retain said gas pressure generating means and having conduits extending between said bore and the interior of the cylin drical member; a first, second, and third piston assembly slidably mounted within said cylindrical member between said choke assembly and the second end of the cylindrical member, said assemblies defining chambers within the cylindrical member wherein a first chamber is defined by said choke assembly and first piston assembly to contain a sealant liquid, a second chamber is defined by said first and second piston assembly to contain a flush fluid, a third chamber is defined by said second and third piston assembly to contain a consolidating fluid, and a fourth chamber is defined by said third piston assembly and second end of the cylindrical member to contain a purge fluid; a pressure operated valve mounted in each of said piston assemblies adapted to open on response to pressure of the gas pressure generating means to permit fluid flow therethrough toward the second end of the cylindrical member; a lower head rigidly attached to the second end of the cylindrical member having a bore extending from the cylindrical member; an elastic packing means circumferentially disposed about said lower head adapted to inflate or deflate upon the entrance of exit of fluid; communication means extending through the lower head from the cylindrical member to said packing means; at least one perforating means mounted transverse to the axis of said cylindrical member adjacent and in communication with said packing means; a fluid pressure responsive firing means in the bore of said lower head operably connected to said perforating means; a fluid passage between the lower portion of said cylindrical member and the packing means; and a pressure responsive exit means adapted to release the excess fluids, and gases created by said gas pressure generating means, whereby activation of the gas pressure means causes expansion of gas in said first chamber forcing said pistons simultaneously towards the second end of said cylindrical member opening said valves and displacing the fluid contained in said fourth chamber through the communication means of said lower head thereby expanding said packing means, and firing said perforated means through said packer means, and easing into the formation, said gas further displacing the fluid contained in said third and second chambers into said formation for the consolidation thereof, whereafter gas pressure is expelled through the pressure responsive exit means deflating the packer means for removal of the apparatus from the well bore.

3. An apparatus as set forth in claim 2 wherein said lower head has an open ended chamber in the lower portion thereof, a slidable piston means adapted to be positioned in said open ended chamber by a flanged plug; a fluid passage means permitting fluid communication between the space between the lower head and said packer means through said lower head and said piston means and plug; a disk means inserted in said fluid passage; a conical housing member rigidly attached to the lower end of said lower head with bore means in communication with the well bore; and a spring means positioned between said housing member and said plug; whereby fluids Within the cylindrical member are displaced against said piston and disk means through the fluid passage means in communication with the packer means allowing expansion except in the event of excess pressure which ruptures said disk means in the fluid passage of said piston and allow fluids in said cylindrical member to be displaced through the conical housing into the well bore.

4. An apparatus as set forth in claim 2 wherein said gas pressure generating means is a propellant charge of slow burning powder ignited by a detonator.

5. An apparatus as set forth in claim 2 wherein said perforating means is a conventional unit comprising a housing containing a detonator connected to the firing means for igniting a propellant to discharge a projectile from the unit.

6. An apparatus as set forth in claim 2 wherein said pressure responsive exit means comprises latitudinal fluid passages in said cylindrical member sealed by a slidable 8 collar means within said cylindrical member, said collar means being positioned by shearable means.

7. An apparatus as set forth in claim 2 wherein said fluid pressure responsive firing means comprises a hydraulie differential switch in communication with the fluids within said cylindrical member and well bore which activates a convention detonation activating means.

8. An apparatus as set forth in claim 3 wherein said conical housing is attached to the lower head by shearable means and is adapted to retain the lower edge of the packing means, said housing being of drillable material.

References Cited in the file of this patent UNITED STATES PATENTS 2,100,807 Kinley Nov. 30, 1937 2,530,805 Bond Nov. 21, 1950 2,541,785 Smith Feb. 3, 1951 2,690,123 Kanady Sept. 28, 1954 2,715,943 True Aug. 23, 1955 2,718,264 Allen et a1 Sept. 20, 1955 2,823,753 Henderson et al Feb. 18, 1958

Claims (1)

1. AN APPARATUS FOR CONSOLIDATING AN INCOMPETENT SUBTERRANEAN FORMATION TRAVERSED BY A CASED WELL BORE COMPRISING AN ELONGATED CYLINDRICAL MEMBER HAVING AN UPPER AND LOWER END; AN UPPER HEAD RIGIDLY ATTACHED TO THE UPPER END OF THE CYLINDRICAL MEMBER WITH A BORE EXTENDING FROM THE LOWER PORTION THEREOF AND A PASSAGE THROUGH THE UPPER PORTION THEREOF IN COMMUNICATION THEREWITH; A CABLE ADAPTED TO SUPPORT SAID APPARATUS AND CONTAINING A CONDUCTOR EXTENDING THROUGH SAID PASSAGE AND ATTACHING TO THE UPPER HEAD BY A SUITABLE MEANS TO ISOLATE SAID PASSAGE AND BORE OF THE UPPER HEAD; A GAS PRESSURE GENERATING MEANS DISPOSED IN THE BORE OF THE UPPER HEAD; A DETONATING MEANS COMMUNICATING WITH SAID GAS PRESSURE GENERATING MEANS AND ATTACHED TO THE CONDUCTOR CONTAINED BY SAID CABLE; A CHOKE ASSEMBLY MOUNTED IN THE LOWER PORTION OF THE BORE OF THE LOWER HEAD TO RETAIN SAID GAS PRESSURE GENERATING MEANS AND HAVING CONDUITS EXTENDING BETWEEN SAID BORE AND THE INTERIOR OF THE CYLINDRICAL MEMBER; AT LEAST A FIRST, SECOND, AND THIRD PISTON ASSEMBLIES SLIDABLY MOUNTED WITHIN THE CYLINDRICAL MEMBER BETWEEN SAID CHOKE ASSEMBLY AND THE LOWER END THEREOF; A PRESSURE OPERATED VALVE MOUNTED IN EACH OF SAID PISTON ASSEMBLIES ADAPTED TO OPEN ON RESPONSE TO PRESSURE OF THE GAS PRESSURE GENERATING MEANS TO PERMIT FLUID FLOW THERETHROUGH TOWARD THE LOWER END OF THE CYLINDRICAL MEMBER; A LOWER HEAD RIGIDLY ATTACHED TO THE LOWER END OF THE CYLINDRICAL MEMBER HAVING A BORE EXTENDING FROM THE UPPER PORTION THEREOF; AN INFLATABLE PACKING MEANS CIRCUMFERENTIALLY DISPOSED ABOUT SAID LOWER HEAD; FLUID COMMUNICATION MEANS EXTENDING THROUGH THE LOWER HEAD FROM THE CYLINDRICAL MEMBER TO SAID PACKING MEANS; AT LEAST ONE PERFORATING MEANS WITHIN SAID LOWER HEAD ADJACENT AND IN COMMUNICATION WITH SAID PACKING MEANS; AND A PRESSURE OPERATED FIRING MEANS WITHIN THE BORE OF THE LOWER HEAD IN COMMUNICATION WITH THE INTERIOR OF THE CYLINDRICAL MEMBER AND SAID PERFORATING MEANS.

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