US2574141A - Apparatus for cleaning perforations - Google Patents

Description

NOV. 6, 1951 3, BROWN 2,574,141

APPARATUS FOR CLEANING PERFORATIONS I Original Filed Oct. 7, 1946 \gllllmll w 7 Iumu Patented Nov. 6, 1951 APPARATUS FOR CLEANING PERFORATIONS Howard C. Brown, Bakersfield, 'Calif., assignor to B. & B. OilTool 00., Bakersfield, Calif., a partnership Original application October 7, 1946, Serial No. 701,644. Divided and this application May 24, 1948, Serial No. 28,942

13 Claims.

My'invention relates to .oil well development and more particularly to improved apparatus for cleaning perforations :in an oil well liner.

It, is a division of my application for United States Letters Patent bearing Serial Number 701,644, filed October 7, .1946, for Method and Apparatus for Cleaning Perforations, "now Patent No. 2,464,669.

In the usual course of producing oil from an oil Well, the perforations in the liner which serve to strain undesirable materials from the flowing oil eventually become clogged with such material. The material which clogs the perforations in the liner may originate in any number of different sources such as the rotary circulating mud deposits from the oil strata and scale or corrosion arising from chemical action on the liner. Such accumulative clogging is inevitable even under the most favorable operating conditions, thus necessitating a periodic cleaning of the perforations in order to maintain the production rate and the potential of the well.

The most common classes of procedures for cleaning the liner perforations that have been used heretofore are: methods involving chemical procedures and methods involving hydraulic procedures and methods involving mechanical procedures. Each of these classes of procedures offers its own advantagesbut frequently the difficulties of one requires the use of another, thus necessitating an extended shut down period for the well.

Accordingly, it is a general object of my invention to provide apparatus for cleaning the perforations of an oil well liner which combines a mechanical and a hydraulic procedure in order to clean the perforations efiectively.

Another general object of my invention is to provide apparatus for cleaning the perforations of an oil well liner which combines a mechanical and a chemical procedure in order to clean the perforations more effectively.

Another object of my invention is to provide a device for cleaning the perforations of an oil well liner which includes a plurality of cleaning members adapted 'to be projected through the perforations into :any material clogging the 'perforations with means carriedby the device adapted to pump fluid "through the perforations upon reciprocation of the device within the liner.

Another object of my invention is to provide a device for cleaning the perforations of an oil well liner with :a plurality of cleaning members which may be readily projected through the perforations :order to break up any material ;clogging them, together with means for sealing off a portion of the annular space between the device and the liner in which it is'usedin order to facilitate the simultaneous forcing of fluid through the perforations in order to disintegrate or wash away the material, or both.

:Another object of my invention is to provide a device for cleaning the perforations of an oil Well liner with a plurality of cleaning members which may be readily projected through the perforations to break up material clogging the perforations, together with means for sealing off -a portion .of the space between the device and the oil well liner in which it is used for subjecting the .sealed off portion to a fluid action, together with means for by-passing fluid past such sealed off portions .inorder to reduce excessive resistance to movement of the device in the oil well liner created by the sealingaction.

Another object of my invention is to provide a device for cleaning the perforations of an oil well liner in the form of a hollow barrel having openings in the side walls thereof provided with cutting blades which are normally urged outwardly through the openings.

A further object of my invention is to provide a device for cleaning vthe perforations of an oil well liner in the .form of a hollow barrel having openings in the walls thereof through which cleaning members are resiliently urged in order to .cut material clogging the perforations of the linerat the same time that fluid is forced through such openings and through the perforations;

In accordance with my invention I provide a perforation cleaner carrying cleaning members such as cutting blades which are bodily movable towards or away from the carrier, with means for forcing fluid through the perforations through which the blades are projected. In one form of my invention the region supporting the cutting blades and the region including the pumping means are coextensive or at least overlap. When using this latter form of my invention the material clogging the perforations of an oil well liner may be subjected to the simultaneous action of mechanical cutting forces and hydraulic forces 'or to the simultaneous action of mechanical cutting forces and chemical treatment. In another form of my invention the cutting blades are installed in one section of the cleaner and the pumping means in another. In this form, the cutting action of the blades and the hydraulic or chemical action of the pumping fluid, or both, are applied to the material clogging some ;of "the perforations alternatively. By

combining in a single operation mechanical and hydraulic or chemical action to remove material clogging the perforations of an oil well liner, my invention makes possible more rapid and thorough removal of such materials from the perforations. By subjecting the material clogging the perforations to a combined mechanical and hydraulic action the material broken up by the mechanical action is dislodged and washed away quickly, permitting other material to fall in its place this also being subjected to similar mechanical and hydraulic action immediately thereafter. By subjecting the material clogging the perforations to a combined mechanical and chemical action the effect of each in breaking up or disintegrating such material is greatly accelerated by the other. In particular by penetrating the material blocking the perforations mechanically with the blades at the time that acid is being applied very even distribution of acid throughout the formation is attained. In order to carry out my invention, I have designed perforation cleaners of simple, rugged construction and relatively low cost which permit the attainment of the results desired at a great saving in operating cost and operating time.

The foregoing and other objects and advantages of my invention will be more readily understood by reference to the following description of specific apparatus embodying my invention. While the main features of my invention have been set out in broad terms in the statement thereof above, other features of my invention which are incorporated in the embodiments specifically illustrated and described herein will become apparent from a reading of the following description in conjunction with the accompanying drawings wherein:

Figure 1 is a side elevational view of a preferred embodiment of my invention;

Figure 2 is a side elevational view of another preferred embodiment of my invention;

Figure 3 is a detailed sectional view of the barrel forming part of the device of Figure 1 and illustrating a preferred form of cleaning implement; and

Figures 4, 5 and 6 are schematic diagrams used in explaining the operation of the cleaning implement.

The well liner perforation cleaning device ilmechanical cleaning members preferable in the form of rigid blades I6 extend laterally from the barrel through apertures I8 in the side wall thereof. These blades I6 are arranged on the barrel both for pivotal movement in a plane parallel to the axis of the barrel and for bodily shifting towards and away from the barrel. Preferably the blades and the apertures through which they project, are distributed more or less evenly and spirally along the length of the barrel and more or less evenly about its periphery. The blades are of such length that they may be extended to outer positions in which their pointed ends project outwardly beyond the cylindrical surface defined by the peripheries of the packmg cups.

The carrier is adapted for attachment to the lowermost end of a string of hollow drill pipe 20 by means of a coupling 22. The lowermost end ofthe barrel I0 is provided with an orifice 26 which communicates with the interior Qf $1 4 barrel through an inwardly opening ball check valve 25.

Referring to Figure 3, there is illustrated a. preferred arrangement of cleaning implement embodied in this form of my invention. This cleaning implement comprises a cleaning member in the form of a blade l6 having a head 26 thereon which is mounted within an enlarged bore 28 with the blade extending outwardly through a narrow longitudinal slot 30. A coil spring 32 is arranged transversely of the cavity 33 in the interior of the barrel I0 and is provided with an end plate 34 to normally urge the head 26 outwardly against a shoulder 36 formed between the cylindrical bore 28 and the slot 30. The spring is held compressed in that position by means of a threaded plug 38 which is screwed into a threaded bore 40 in the wall of the barrel I0 directly opposite the first mentioned bore 28. The cuttin blade I6 is of flat rigid construction terminating in a sharp point at the outer end thereof. The head 26 is of hexagonal cross-section in the longitudinal plane of the barrel, the two vertical sides being elongated and the upper and lower ends being in the form of right angle points. Each of the cleaning implements projecting blades through the apertures of the barrel I0 is of similar construction.

Considering the action of the cutting blades, normally the blades I6 project radially outward and upward from the barrel I0 as the device is lowered in a well liner for the first time, until the tool reaches the bottom of the first downward stroke. Then the tool is elevated and when a blade reaches the edge of a perforation ll of the liner 42, it may be forced directly outward and upward through the perforation slot, digging into any material directly behind the perforation slot by the combined force of the elevation of the barrel I 6 and the action of the corresponding spring 32, if the material is soft enough.

Elevation of barrel ID causes bore 28 to lift up against the inner end 26 of blade I6, thus causing blade I6 to be driven into the formation. This is a frictional metal to metal drive which exerts great leverage force against blade I6. As the raising of the device continues the blade I6 may break up such material by a cutting and digging arc action. When the blade reaches the upper edge of the perforation slot the upper edge of this slot arrests further upward move ment of the blade and acts as a fulcrum to lever the blade outwardly and in a downward arc, and head 26 is rocked inwardly against the action of the spring 32 until blade I6 is completely withdrawn from the perforation in a downwardly inclined position relative to the axis of the barrel, thus completing the are. When the downwardly inclined blade next registers with a perforation slot on this upstroke it will rock back to its radial position and dig and out into the material clogging that second perforation if the material is not too hard. One or both of these cutting actions occurs each time that a blade I6 registers with a perforation slot whenever the device is raised or lowered in the well, the lower ing actions, after the first one, being the reverse of the raising actions described above.

This raising and lowering is continued until the perforations being worked on are clean. 0rdinarily the preferred method is to clean a predetermined length of liner by raising and lowering within that length a predetermined number of tini s- Then t e ne t section of liner of that perforations Li I.

predetermined length is cleaned and this is repeated until the entire perforated area is cleaned and the job is finished.

In using this device to clean the perforations of a well liner G2, which have become clogged by the accumulation of any material in the perforations, the device is lowered into the well upon the bottom of a string of tubing or drill-pipe. As it is being lowered, the packing cups establish seals with the inner wall of the liner, thus sealing Off an annular ring space as between the barrel and the liner and between the upper and lower pairs of packing cups. As the device is lowered into the well, the inwardly opening check valve 25 at the bottom of the barrel opens, admitting fluid into the barrel and thence into the tubing or drill pipe, thus reducing the resistance to the iowering of the device in the well created by the sea-ling action of the packing cups. As the device is lowered in an unperforated portion of the liner the weight of the drill pipe actting downwardly forces the fluid within the liner below upper cups l2 to flow into the apertures E8 in the side of the barrel H! from the annular ring space M and thence inside the barrel i0 past the upper packing cups l2 into the tubing or drill pipe 20.

As the lowering of the device continues beyond the point where the upper packing cups l2 have passed some of the perforations, fluid is forced outward through the perforation slots 4! into the space behind the liner and thence upwardly and back into upper annular space 46 through the liner perforations above .the upper packing cups l2.

When the device is subsequently .raised in the well, the check valve 25 closes preventing egress of fluid from the interior of the barrel through its bottom opening 24. Thus,.closing valve 25 as the device is raised causes the fluid within the tubing or drill pipe 253 to be discharged outwardly through the apertures I8 in the barrel l8 into the annular ring space 44 between the packing cups and thence outwardly through the .At the same time well fluid which is located in the annular spaces 44 and iii between the tubing 01' drill pipe and the well liner is forced outwardly through the perforations above the lower packing cups l4 through perforation slots 4| into the space outside the well liner. All of the fluid thus forced out of the perforations above the lower packing cups flows downwar ly outside of the liner and back into the liner through perforations below the lower packer cups I4.

This method and result is reversed on each downward stroke.

Thus, as the device is raised and lowered in the well the packing cups and the check "valve cooperate to pump fluid through the perforations at the'same time that the blades are working in them, and thus they aid the cutting blades in removing material that is clogging the perforations. It is to be noted that both in the raising and the lowering of this device in the well, fluid is forced outward through the perforations H in which the blades are working, thus reducing the likelihood of broken up material entering the annular ring space 44 between the packing cups. While the fluid flow action may vary somewhat from time to time, according to circumstances, it will be understood that my invention is not limited to the specific fluid flow action just described; this fluid flow action being set forth merely to facilitate the understanding of the operation of this device in cleaning the perforat-ions.

.Also this flow of fluid surging out and in through perforation slots 4| may be effected directly from the surface by forcing fluid underpressure down through pipe *20 and slots la in barrel NJ between cups l2 and Hi into space 4'4 and thence through slots 4| into the space outside the linerand thence up past cups i2 and back through perforations 4| above upper cups [2 into space 46 and :on up to the surface if a complete return of circulating fluid is desired.

In a preferred method of utilizing my invention, a chemical substance, such as acid, which is reactive with material likely to be clogging the perforations may be injected into the well by any method described above. When this acid is so positioned within the well, it is forced to flow through the perforations simultaneously with the cutting by the blades l6 of material clogging the perforations by the same method as the non-acid fluid described above.

The material clogging the perforations is thus rapidly disintegrated by the combined mechanical, fluid and chemical action. This throws the acid farther out through perforation slots 4| than is accomplished by ordinary acid flushing methods.

Thus, instead of the acid being applied at the mouth of the perforation slots 4|, as in previous methods, my .method projects the acid immediately beyond slots Ail to the sand face outside the liner by the assistance of the combined knife and hydraulic action.

In another embodiment of my invention illustrated in Figure 2 I utilize a carrier 50 in the form of a solid cylindrical body 52 at the lower end thereof and a hollow tubular portion 54 at the upper end thereof. A plurality of cutting blades 56 is projected outwardly of the cylindrical body 52 through slots 58. These blade assemblies are of the same general type as that herein-before described in detail (see Figure 3) except that the-spring is arranged in a single radial bore that extends substantially all the way through the cylindrical body from one side thereof toward the other and there is no central cavity within or passage through the body 52 which intersects this bore. Accordingly these blades 56 likewise are adapted for pivotal movement in a plane parallel to the axis of the cylindrical body and for bodily shifting towards and away from the body, like blades l6, described above.

The tubular portion 54 is adapted at its upper end for attachment to the lowermost end of a string of tubing or drill pipe 58 by means of a coupling 60. This tubular portion 54 is provided with an orifice 62 in the side wall thereof intermediate its ends and has mounted thereon opposed upper and lower pairs of packing cups 64 and '66, arranged respectively above and below the orifice 52. A by-pass pipe 68 arranged within this tubular position 5% terminates at the lower end in the lower opening 10 beneath the lower pair .of packing cops 66 and at the upper end in an upper opening l2 above the upper packing cups ea.

As this device is lowered in an oil well the packing cups contact the liner of the well and seal off an annular ring space 1 3 between the tubular portion of the carrier and the well liner and cups 64 and 66. This annular space communicates with the interior of the drill pipe through the orifice 62 in the wall of the tubular portion. As the device is lowered in a portion of the liner having no perforations therein, some of the fluid in the space 16 in the liner beneath the device is forced through the by-pass pipe into the annular space 18 between the drill pipe and the liner above the packing cups 64 and 66, and some leaks past the lower packing cups 66 into the annular ring space 14 and thence through the orifice 62 into the tubular member and thence into the drill pipe '58. Finally when the blades 56 of the device encounter perforations in the liner the blades are projected outwardly through the perforations into any material clogging the perforations breaking up this material in the manner hereinbefore described.

Fluid is forced outward through the perforations in the portion of the liner between the two sets of packing cups by pressure from the surface and thence outside the liner and then inwardly through the perforations above or beneath the packing cups. Finally during the raising of the device into a portion of the liner which is not perforated fluid above the packing cups 64 flows into the region below the packing cups 66 through the b-y-pass pipe 68.

During the reciprocation of this device upward and downward within the perforated portion of the liner, fluid is forced from the surface through pipe 58 to the perforations in which the blades have worked. This flushing and washing action thus cooperates with the digging and cutting action of the blades to accelerate the removal of material clogging the perforations far beyond the speed with which such removal could be accomplished by either action alone or by both actions in separate consecutive operations, thus effecting a great saving in time and cost. Clearly, of course, chemical action could also be added to accelerate the cleaning of the perforations still further in accordance with the principles hereinbefore set forth.

From the foregoing description of my invention it will be clear that I have provided a well liner perforation cleaner which combines and improves the advantages of mechanical, chemical and hydraulic well liner perforation cleaners heretofore available, The use of my Well cleaner is of advantage both in initial completion and subsequent treatment of a well. When used in initial completion of a well the Opening and cleaning of all perforations of a well liner is assured through the removal of the mud cake and stray cement from the perforations, thus exposing the complete sand face of the formation from which production is desired to the perforated liner and assuring uniform distribution of fiow into the well from the formation. The opening of all of the perforations promotes the even distribution of the washing action through all possible channels throughout the length of the liner rather than through the few channels which happen to be weakest at the outset, thus precluding the possibility of the flow concentrating in a small portion of this liner thereby producing corresponding high velocity of flow in that region with the resultant excessively high debris carrying capacity associated with such high fluid velocity. The form of my invention which involves chemical treatment has the advantage of assuring an even distribution of chemicals through the zone to be treated and the subsequent thorough and rapid removal of the spent chemical after the treatment has been completed.

The use of my perforation cleaning system is particularly advantageous when preparing a well for a potential test as the thorough cleaning of the perforations permits the well to operate at its maximum rate. Cleaning of the space behind the well liner may also be accomplished by my method, thus facilitating the preparation of a liner for withdrawal from the well. My well cleaning system is also advantageous for use in opening up the perforations of a liner to facilitate the even distribution of cement or plastic in a plugging 'job.

While particular arrangements and specific details have been set forth in this specification for the purpose of completely illustrating two preferred embodiments of apparatus with which the method of my invention may be used and for completely illustrating the principles involved in its operation, it is to be understood that my invention in its broader aspects is not limited to such details, reference being made to the following claims for a definition of my invention in both its broad and narrow aspects.

I claim:

1. A device for cleaning perforations in an oil well liner comprising a carrier having a longitudinal cavity therein open at one end adapted to be supported upon the bottom of a string of hollow pipe; a plurality of cleaning members extending laterally from the carrier, each of said cleaning members being fioatingly mounted within an enlarged bore arranged transversely of said cavity in the carrier for both pivotal movement and bodily shift towards and away from the car rier; a coil spring mounted in each said transverse bore for urging said cleaning members laterally outward from the carrier towards extended positions thereby causing the cleaning members to enter perforations in said liner; means defining an orifice in the carrier wall for establishing communication between th interior of the carrier and the annular space between the carrier and said liner; and means including a packing element adapted to operate as a seal in the liner for pumping fluid along a path passing through said orifice and said annular space and perforations in said liner.

2. A device for cleaning perforations in an oil Well liner comprising a carrier adapted to be supported upon the bottom of a string of hollow pipe and having a longitudinal cavity therein open to the interior of said pipe; a plurality of cleaning members extending laterally from the carrier,

- otal movement and bodily shift towards the carrier; a coil spring mounted in each said transverse bore for urging said cleaning members laterally outward from the carrier towards extended positions thereby causing the cleaning a members to enter perforations in said liner; a

' pair of opposed packer elements mounted upon said carrier for establishing seals between said carrier and said liner above and below said cleaning members; means including an orifice in the carrier wall between the packing elements for establishing communication between the interior of said pipe and the annular space surrounding the carrier between the packing elements.

3. A device for cleaning perforations in an oil well liner comprising a carrier adapted to be supported upon the bottom of a string of hollow pipe; a plurality of cleaning members extending laterally from the carrier at the lower portion thereof, each of said cleaning members being floatingly mounted within an enlarged bore arranged transversely of said carrier in the carrier gratin for both pivotal movement and bodily shift towards and away from the carrier; yielding coil spring means mounted in said transverse bores for urging said cleaning members laterally outward from the carrier towards extended positions thereby causing the cleaning members to enter perforations in said liner; a pair of opposed packer elements mounted upon said carrier at the upper portion thereof for e'stablishing'a pair of seals between said carrier and said liner; and means including an orifice in the carrier wall between the packing elements for establishing communication between the interior of, said pipe and the annular space surrounding the carrier between the packing elements. v

4. A device for cleaning perforations in an oil well liner comprising a carrier adapted to be supported upon the bottom of a string of hollow pipe; a plurality of cleaning members extending laterally from the carrier at the lower portion thereof, each of said cleaning members being fioatingly mounted within an enlarged bore arranged transversely of said carrier in thecarrier. for both pivotal movement and bodily shift towards the carrier; a coil spring mounted in each said bore for urging said cleaning members, laterally outward from the carrier towards extended positions thereby causing the cleaning members to enter perforations in said liner; a pair of opposed packer elements mounted upon said carrier at the upper portion thereof, for establishing a pair of opposed seals between said carrier and said liner; means including an orifice in the carrier wall between the opposed packer elements for establishing communication between the interior of said pipe and the annular space surrounding the carrier between the 'opposed packer elements; and means establishing a fluid by-pass passage in said carrier, said passage having an opening located above and anopening located below said opposed packer elements.

5. A device for cleaning perforations-in an oilwell liner comprising a carrier adapted to be supported upon the bottom of a string of hollow pipe; a plurality of cleaning members extending laterally from the carrier, each of said cleaning members being floatingly mounted within an enlarged bore arranged transversely of said carrier in the carrier for both pivotal movement and bodily shift towards the carrier; a coil spring mounted in each said transverse bore: for urging said cleaning members laterally outward from the carrier towards extended positions thereby causing the cleaning members to enter perforations in said liner; a pair of opposed packer elements mounted upon said carrier for establishing seals between said carrier and said liner above and below said cleaning members; means including an orifice in the carrier wall between the packer elements for establishing communication between the interior of said pipe and the annular space surrounding the carrier between the packer elements; and means establishing a fluid by-pass passage in said carrier, said passage terminating in a pair of openings located respectively above and below said packer elements.

6. A device for cleaning perforations in an oil well liner comprising a carrier adapted to be supported upon the bottom of a string of hollow pipe; a plurality of cleaning members extending laterally from the carrier, each of said cleaning members being floatingly mounted within an enlarged bore arranged transversely of said carrier in the carrier for both pivotal movement and bodily shift towards the carrier; a coil spring mounted in each said transverse, bore for urging said: cleaning members laterally outward from the carrier towards extended positions thereby causing the cleaning members to enter perforations said liner; a pair of opposed packer elements mounted upon said carrier for establishing seals b'etw'een'said carrier and said liner above and below said cleaning members; and means including an orifice in the carrier wall between the packer elements for establishing communicationbetween the interior of the pipe and the annular space. surrounding thecarrier between the packer elements.

7; A device for cleaning perforations in an oil well liner comprising a hollow barrel adapted to be supported at its upper end upon the bottom of a string of hollow pipe, and having a plurality of apertures in the wall thereof for establishing communication with the interior of said pipe; a plurality of cleaning members extending laterally through said apertures, each of saidcleaning members being noatingly mounted within an enlarged bore arranged transversely of said barrel in the barrel for both pivotal movement in said openings and bodily shift into and out of said openings; a coil spring mounted in each said transverse bore for urging said cleaning members laterally outward through said apertures towards extended positions thereby causing the cleaning members to enter'saicl perforations; means for sealing off the space bet'ween the apertured. portion of the barrel and the ad.- jacent portion of a liner which it is working whereby fluid may be pumped along paths passtom of a string of hollow pipe and having a plurality of openingsin the wall thereof for establishing communication with the interior of said pipe; a plurality of cleaning members extending laterally through said openings, each of said cleaning members being floatingly mounted within an enlarged bore arranged transversely of said barrel in the barrel for both pivotal movement in. said openings and bodily shift into and out" of' said openings; a coil spring mounted in each said transverse bore for urging said cleaning members laterally outward through said openings towards extended positions thereby causing the cleaning members to enter perforations in said liner; and a pair of packer elements respectively mounted on opposite sides. of said plurality of cleaning members for establishing seals between saidbarrel and; said liner at positions above and below said plurality of cleaning members; and' an inwardly opening.

check valve at'the bottom end of saidb arrel for preventing flow of fluid outwardly of the barrel at the bottom end thereof.

9. A' device for cleaning perforations in an oil wellliner comprising a hollow barrel adapted tobe supported at its. upper end upon the bottom of a string of hollow pipe and having a plurality of apertures in the wall thereof and another opening at the bottom thereof for establishing communication with the interior thereof; a-plii'- rality of cleaning members extending laterally through said apertures, each of said cleaning members being floatingly mounted within an enlarged bore arranged transversely of said barrel in the barrel for both pivotal movement in said openings and bodily shift into and out of said opening; yielding coil spring means mounted in said transverse bores for urging said cleaning members laterally outward through said apertures towards extended positions thereby causing the cleaning members to enter perforations in said liner; a packer element mounted on said barrel between said apertures and said opening, said packer element being adapted to act as a piston in said liner; and an inwardly opening check valve in said barrel for causing fluid to pass through said opening in an upward direction only whereby reciprocation of said device in said liner causes fluid to be pumped into said liner through perforations beneath said packer element and out of said liner through perforations above said packer element.

10. In a device for cleaning perforations in an oil well liner, the improvement which comprises: a hollow barrel adapted to be supported at its upper end upon the bottom of a string of hollow pipe, said barrel having a plurality of transverse recesses in the inner wall thereof and a plurality of vertical slots in the outer wall thereof extending parallel to the axis of said barrel and communicating with the respective transverse recesses, said transverse recesses providing inner shoulders between said transverse recesses and said vertical slots, a plurality of rigid cutting blades extending laterally outward through said slots, each of said blades being provided with an enlarged'head within the corresponding transverse recess, thickness of said enlarged heads being greater than the width of said vertical slots, and yielding coil spring means within the said respective transverse recesses for urging said heads laterally outward toward the respective shoulders of said transverse recesses; said cutting blades and said yielding coil spring means being so arranged'as to force said blades into material obstructing said perforations upon raising and lowering said device in said liner.

11. A device for cleaning perforations in an oil well liner comprising: a hollow barrel adapted to be supported at its upper end upon the bottom of a string of hollow pipe, said barrel having a plurality of transverse recesses in the inner wall thereof and a plurality of vertical slots in the outer wall thereof communicating with the respective transverse recesses, said transverse recesses providing inner shoulders between said transverse recesses and said vertical slots; a plurality of cleaning members extending laterally outward through said vertical slots, each of said cleaning members being provided with an enlarged head within the corresponding transverse recess the thickness of said enlarged heads being greater than the width of said vertical slots;-

yielding coil spring means within the said transverse recesses for urging said heads laterally outward toward the respective shoulders of said transverse recesses, said cleaning members and said yielding coil spring means being so arranged as to force said cleaning members into material obstructing said perforations upon raising and lowering said device in said liner; and a pair of packer elements mounted on said barrel on opposite sides of said plurality of cleaning members.

12. A device for cleaning perforations in an oil well liner comprising: a hollow barrel adapted to be supported at its upper end upon the bottom of a string of hollow pipe, said barrel having a plurality of transverse recesses in the inner wall thereof and a plurality of vertical slots in the outer wall thereof communicating with the respective transverse recesses, said transverse recesses providing inner shoulders between said transverse recesses and said vertical slots; a plurality of cutting members extending laterally outward through said vertical slots, each of said cleaning members being provided with an enlarged head floatingly mounted within the corresponding transverse recess the thickness of said enlarged heads being greater than the width of said vertical slots; yielding coil spring means within the said transverse recesses for urging said heads laterally outward toward the respective shoulders of said transverse recesses, said cleaning members and said yielding coil spring means being so arranged as to force said cleaning members into material obstructing said perforations upon raising and lowering said device in said liner; a pair of packer elements mounted on said barrel on opposite sides of said plurality of cleaning members; and an inwardly opening check valve at the bottom of said barrel for preventing flow of fluid outwardly of the barrel at the bottom end thereof.

13. In a devicefor cleaning perforations in an oil well liner the improvement which comprises: a hollow barrel adapted to be supported at its upper end upon the bottom of a string of hollow pipe, said barrel having a plurality of bores extending laterally and transversely through the wall thereof and a plurality of inner recesses in the inner wall thereof opposite the respective transverse bores and a plurality of vertical slots in the outer wall thereof communicating with the respective recesses, said recesses providing inner shoulders between said recesses and said vertical slots; a plurality of cutting blades extending laterally outward through said vertical slots, each of said cutting blades being provided with an enlarged head fioatingly mounted within the corresponding recess the thickness of said enlarged heads being greater than the width of said vertical slots; a plurality of coil springs arranged transversely of the axis of the barrel and along the respective axis passing through said transverse bores and the opposed recesses for urging said heads laterally outward toward the respective shoulders of said recesses whereby said blades are urged laterally toward extended positions thereby causing the blades to enter perforations in said liner; and retaining means in said transverse b bores for holding said coil springs in operative positions in the said transverse bores.

HOWARD C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

Images