US3308893A - Downhole horizontal slotting tool - Google Patents

Description

March 14, 1967 J. D. WISENBAKER ETAL 3,308,893

DOWNHOLE HORIZONTAL SLOTTING TOOL 5 Sheets-Sheet Filed Dec. 51, 1963 INVENTORS 5 yam/54kg@ l. ys.

United States Patent O 3,308,893 DWNHOLE HURIZUNTAL SLOTTING TOOL John D. Wisenbaker and Robert W. Stuart, Dallas, Tex.,

assignors of one-half each to American Coldset Corporation, Teterboro, NJ., a corporation of Texas, and

Core Laboratories, Inc., Dallas, Tex.

Filed Dec. 3l, 1963, Ser. No. 334,819 7 Claims. (Cl. 17E- 40) This invention relates to a tool for making horizontal slots in the sidewalls of either cased or uncased well boreholes.

In the drilling7 and production of oil and gas wells, a horizontal slotting tool has many useful applications, principally in connection with well completion and well treatment.

Wells are sometimes completed by setting and cementing casing into the top portion of the producing horiz-on and leaving the pay zone as open hole. However, in most wells the casing extends through all, or a major portion of the productive interval, and cement lls the space between the casing and the Wall of the borehole. The casing and the cement sheath are then perforated opposite the selected interval to permit flow of fluid from the formation into the wellbore.

Common perforating techniques in commercial use today involve the use of perforating guns which employ high explosives to re steel projectiles through the casing and cement sheath and into the surrounding formation or which develop high temperature, high velocity jet Streams from shaped charges which penetrate the casing and cement sheath and a portion of the surrounding formation. These methods have certain disadvantages, one of the more notable ones being that the guns frequently misfire, and sometimes the projectiles fail to penetrate the casing. Either occurrence not only fails to provide the proper perforation, but also leaves in the well metallic debris which may seriously interfere with subsequent operations. Moreover, the use of c-onventional perforating guns or jets results in the formation of a limited number of relatively small perforations at spaced points which, particularly in dense formations of low permeability, may substantially restrict the rate of production of the Well. And, further, the spent bullets and jet cases remain in the formation directly opposite the perforations and interfere, in varying degrees, with ow into the perforations. No positive measure of the adequacy or inadequacy of the penetration made by the perforating guns can be made. Thus, it is extremely difficult to determine whether the ultimate production rate is limited by the surrounding formation or by the inadequacy of the perforation.

Large perforations and slots are also sometimes made by means of abrasive jet tools whereby a high velocity streams of abrasive particles in a liquid medium is directed against the surface to be penetrated. Major disadvanytages of this procedure are that it requires the running of pipe to conduct the abrasive uid, requires special pumping equipment to develop required jet velocity, provides no indication of degree of penetration and leaves abrasive material in the hole for removal by expensive means.

Still another way of providing perforated ycasing for the purpose of well completion is to pre-perforate sections of casing at the surface and incorporate them in the casing string at the desired point. Although this method has the advantage of making it possible to provide larger openings and even slots of any desired length, it is obviously relatively expensive and troublesome. Moreover, it is extremely difcult to place the perforated section of casing at exactly the desired horizon in the well, and an error in its placement will result in opening up the 3,308,893 Patented Mar. 14, 1967 Well at the wrong point, either missing the desired formation altogether or excluding part of the desired formation while opening up adjacent formations which may admit water into the well, seriously limiting or even effectively destroying its useful oil production capacity.

Another important use of casing perforations is in connection with squeeze cementing operations, such as are performed in an attempt to shut off the flow of water from lower zones, close the perforations used in drill stem testing and improve the bond or seal between the casing and the formation. These cementing operations normally involve forcing a cement slurry through the casing perforations. Where the perforations are formed by a perforating gun or jet as described above, the limited ow capacity of the relatively small, spaced perforations may restrict the efficacy of the operation.

Casing perforati-ons are also used for such operations as hydraulic fracturing. While the fracturing uid can be injected through the multiple spaced perforations created by a perforating gun or jet, current technology favors injection of the fracturing fluid through a single linear opening, such as the horizontal slot formed by the tool of the present invention, to control the plane of fracture initiation and to concentrate the fluid and achieve greater penetration of the fracture into the surrounding formation.

Another principal use of horizontal slots is for cutting casing, for example where the casing is to be pulled from the well. Horizontal slots are also used for various types of well treatment, such as water injection, with or without tracers, and possibly for fishing and other remedial operations.

The present invention provides a simple, inexpensive, and practical downhole tool for forming horizontal slots in casing or in the sidewall of uncased holes. Although the particular tool illustrated and described herein is capable of forming only one circumferential slot at a time, it can be used to form any number of vertically spaced slots, one after the other, during a single trip into the borehole. It will also 4be understood that the tool may easily he modified to provide a plurality of vertically spaced cutting assemblies for cutting a number of slots at the same time.

The horizontal slots formed by the tool not only afford excellent communication between the borehole and the surrounding formation, either for purposes of well production or for purposes of injection of cement slurries, fracturing or treating liquids and the like, but also insure positive penetration not only of the casing but of the cement behind the casing and even the adjacent portion of the surrounding formation, if desired, and obviate leaving in the borehole any metallic debris or other junk which might interfere with subsequent operations.

Since the slotting tool of the present invention may be lowered into the borehole on a wire line, and does not involve one or more round trips into the hole with pipe, as in the case of most prior slotting tools, its operation is rapid and inexpensive. Moreover, it is possible to position the slots at the desired depth with extreme accuracy. For example, the slotting tool may be lowered into the borehole on the same wire line apparatus which was employed in making the usual downhole electrical or radioactivity logs, so that, even though there is an indeterminate error in the absolute depth indication of the wire line depth gauge, so long as its indications are repro-ducible, the slotting tool can be positioned at a depth corresponding to any selected point on the downhole log. Alternatively, the electrical or radioactivity detector sonde may be lowered into the borehole simultaneously with the slotting tool, with the two in predetermined spatial relation on the same wire line, so that the electrical or radioactivity plot may be traced or retraced until the desired point is reached.

I n addition, the downhole radioactivity log may be correlated with a surface log of radioactivity made on core samples at the surface of the ground according to the method disclosed in U,S. Patent No. 3,025,398, to insure that the slotting tool is positioned to perforate the casing opposite the formation from which any selected core sample or group of samples was taken. Similarly, the downhole radioactivity log from the well in question may be correlated with downhole radioactivity logs made in adjacent wells to position the slotting tool adjacent a selected formation which is thus clearly identied from well to well.

In the drawings:

FIGURE l is a foreshortened vertical sectional view through a cased borehole containing a horizontal slotting tool embodying7 features of the present invention, with the tool being shown partly broken away to reveal its inner construction.

FIGURE 2 is a vertical sectional view, at enlarged scale, through the lower portion of the tool of FIGURE 1.

FIGURE 3 is a fragmentary vertical sectional view, at still further enlarged scale, through a lower portion of the tool, showing in particular the scriber for recording the extent of penetration of the cutter blades.

FIGURES 4, 5 and 6 are transverse sectional views taken respectively along the lines 4 4-, 5 5 and 6 6 of FIGURE 2, and at the same scale as FIGURE 2.

FIGURE 7 is an enlarged, fragmentary longitudinal sectional view taken on the line 7 7 of FIGURE 6.

FIGURES 8 and 9 are respectively staggered longitudinal and transverse sectional views through the lower end portion of the tool with the cutter blades shown in the fully extended position.which they occupy during the latter portion of the slotting operation.

In FIGURE 1, the reference numeral 10 identifies the sidewall of a typical well borehole which is lined with a steel casing 12, with cement 14 filling the annular space between the casing 12 and the sidewall it). Shown suspended in the borehole on a wire line 16 as an illustrative slotting tool embodying features of the present invention.

The tool includes a tubular housing 18 enclosing an elongated electric motor 20 which is axially supported in the housing by spacers 22. Removably attached to the drive shaft 24 of the electric motor 2G and projecting downwardly below the lower edge of the tubular housing 18 is a rotor assembly which is generally designated 26 in FIGURE l and is shown in greater detail in FIGURES 2-9.

As best seen in FIGURE 2, the rotor assembly is supported on an axial shaft 28 which is removably attached at its upper end to the motor shaft 24 and carries at its lower end a supporting block 30 which is fixed to it by a removable pin 31. The block 3) is provided with a deep circumferential slot 30a in which a pair of cutter blades 32 are received, the cutter blades 32 being keyed by pins 34 on jack shafts 36 which are rotatably supported in the upper and lower portions of the block 38. Washers 38 interposed between the upper and lower faces of the cutter blades 32 and the adjacent faces of the slot 30a in the block 30 tix the shafts 35 against axial movement in the block 30 and prevent engagement of the cutter blades 32 with the upper and lower faces of the slot 30a to permit easy rotation of the cutter blades 32.

Keyed to the upper ends of the jack shafts 36 by pins 40 are pinions 42 which mesh with a ring gear 44 keyed to a sleeve 46 which is rotatably supported on the shaft 28 between the upper face of the block 3i) and the lower face of the mounting flange 28a at the upper end of the shaft 28. Supported on the sleeve 46 and extending radially outward therefrom is a set of four symmetrically spaced varies 48 which, like the remainder of the cutter assembly 26, are immersed in the drilling mud which is circulated into and out of the borehole during the rotary drilling operation and which remains in the well to prevent blowouts until the well has 'been completed for production.

As will be understood, the two cuter blades 32 always move inwardly and outwardly in unison, being coupled together through their respective pinions 42 and the ring gear 44 (FIGURES 2 and 4). As best 'shown in FIG- URE 6, the cutter blades 32 are normally retained in their inner position, fully retracted within the slot Sila of the lock 3i), in which position they are shown in full lines in FIGURE 6, by a detent 50 which engages the outer edge of one of the two cutter blades 32. As shown in detail in FIGURE 7, the detent 5i) is received in a recess 3ilb in the lower portion of the block 30 and is urged upwardly by a helical spring 52 which is cornpressed between the lower end of the recess 30b and the under surface of the enlarged head portion of the detent Si). The upward movement of the detent 50 under the iniluence of the spring 52 is limited by engagement of a head 50a formed on the lower end of the detent 50 with the under surface of the block 30. The upper surface of the detent 5t) which projects upwardly into the slot 30a in the path of one of the cutter blades 32 is beveled so that it can be cammed downwardly against the resistance of the spring S2 by the edge of the cutter blade 32 to permit movement of the cutter blade to and from its inner, retracted position.

As shown in FIGURES 2 and 5, mounted in the ring gear 44 and projecting downwardly from the lower face thereof is a stop pin 54 which projects into an arcuate slot 30C formed in the upper surface of the block 30. Engagement of the pin 54 with the ends of the slot 30C limits the movement of the cutter blades 32.

As shown in FIGURE 2, also supported in the ring gear 44 is a stylus which is generally designated 56 and which is shown in greater detail in FIGURE 3. As may be seen in the latter figure, the stylus 56 is slidably received in a recess 44a in the ring gear 44 and is urged downwardly by a helical spring 58 which is compressed between the upper end of the stylus 56 and the inner face of a plug 6) which is threaded into the upper end of the recess 44a. The pointed lower end of the stylus 56 projects into an arcuate recess 38d formed in the upper surface of the block 3i? and bears against an arcuate sheet 62 of soft and readily malleable material, such as lead, which tits snugly in the slot 36d and is supported on its bottom surface. As the ring gear 44 rotates, rotating the pinions 42 to swing the cutter blades 32 outwardly, the stylus 56 inscribes a readily visible mark in the malleable sheet 62, the angular extent of this mark being indic ative of the degree of extension of the cutter blades 32.

The tool may also be provided with means for centering the housing 18 in the borehole. The particular means illustrated in FIGURE l is of the conventional spring-basket type, including a plurality of spring fingers which are positioned in vertical slots 18a spaced around the housing 18. The upper ends of the ngers are xed to a cylindrical band 72 which in turn is secured to the housing 18, while their lower ends are secured to another band 74 which is slidable vertically of the housing 18. When the lower band 74 is in its lowermost position, as shown in full lines in FIGURE 1, the spring fingers 70 `are tlat against the sides of the housing 18; when the lower band 74 is raised, the spring fingers 7i) are bowed outwardly, as shown in broken lines, thus engaging the sidewalls of the borehole to center the housing 18 in the borehole.

The lower band 74 is actuated by cables 76 secured thereto and extending upwardly along the inner walls of the housing 18, around pulleys 78 rotatably supported on the housing and nally around a drum 80. The drum 8l) is driven through a slipping clutch 82 by a fractional horsepower electric motor 84.

While only one centering assembly is shown, it will be understood and two or more centering devices of this or other type could be provided.

The operation of the tool is as follows:

The tool is lowered into the borehole on the wire line 16 to the desired depth, as determined in the manner hereinabove described. When the tool has reached the desired depth, the feeding of the wire line 16 is stopped and electrical power is supplied to the motor S4 through a pair of conductors in an electrical cable associated with the wire line 16 (not separately shown), said current being controlled by a switch on the control panel 64 at the surface of the ground. This causes the motor S4 to rotate, driving the drum 80 to reel in the cables '76. This raises the lower band 74 and causes the spring ngers 70 to bow outwardly into engagement with the sidewalls and center the housing 18 in the borehole. When the spring lingers 70 are in rm compressive engagement with the sidewalls and thus strongly resist further upward movement of the lower band 74, the slipping clutch 82 will slip during continued running of the motor 84.

Power is then supplied to the motor 20 through a separate pair of conductors in the electrical cable, and a separate switch on the control panel 64, causing motor 20 to rotate the rotor assembly 26 at a relatively high speed in the clockwise direction, as viewed in FIGURE 6. The immersionfof the vanes 48 in the drilling fluid creates a resistance to rotation of the vanes 48 and the sleeve 46 on which they are fixed and thus causes the ring gear 44 to rotate in a counterclockwise direction relative to the shaft 28 and block 30, as illustrated in FIGURE 4. This rotation of the ring gear 44 rotates the pinions 42 in a clockwise direction and causes the cutter blades 32 to move outwardly from their normal inner positions, in which theypare shown in full lines in FIGURE 6, to outer positions in which they are shown in broken lines in that figure, the detent 50 being cammed out of the way by the edge of one of the blades 32 during such movement.

The outer end portions of the two cutter blades 32 are studded with industrial diamonds or other hardened, projecting cutter elements, as indicated at 32a in FIGURES 6, 8 and 9. As the rotating blades come into engagement with the inner surface of the casing 12, they therefore commence to cut into the casing, the centrifugal force imposed upon the blades, as Well as the rotational force imposed upon them through the gears 42 and 44 from the vanes 48, furnishing the pressure of the blades against the work surface necessary to effect an eflicient and relatively rapid cutting operation. As shown in FIGURES 8 and 9, the cutting may continue until there is formed a slot 66 which extends not only through the casing 12 but also through Ithe cement 14 behind it and for some distance into the surrounding formation.

When the cutting operation has been completed, the electrical current supplied to the motor 20 from the con- 4trol panel 64 is reversed or shifted in phase, causing the motor 20 "to be driven in the opposite direction. Thus, the rotation imparted to the vanes 48 and sleeve 46 relative to the remainder of the rotor assembly is reversed with respect to that previously described and this rotates the gears 42 in the opposite direction, withdrawing the cutter blades 32 into their inner retracted positions, against the resistance of the detent 50, which holds them in place once they have reached their fully retracted positions, as shown in full lines in FIGURE 6. The electrical power to the motor 84 which actuates the centering assembly is reversed or shut off, reversing or stopping the motor 84, thereby relaxing the tension on the cables 76 and allowing the inherent resiliency of the spring ngers 70 to straighten them again, retracting .them from contact with the sidewall and against the housing 18.

The tool may then be withdrawn from the Well, and the degree of penetration of the slot 66 ascertained by removing the pin 31, sliding the block 30 and its associated shafts 36 and gears 42 olf the end of the drive shaft 28, and examining the line inscribed on the malleable sheet 6 62. The inscribed sheet 62 is removed and replaced by a fresh sheet preparatory to reusing the tool.

From the foregoing description, it will be appreciated that the present invention thus provides an extremely simple and practicable tool which can be lowered into a borehole on a single wire line and used for rapidly forming horizontal (Le. peripheral) slots in either cased or uncased wells and which will afford a positive indication of the degree of penetration of the slots thus formed. It will .therefore be appreciated that the aforementioned and other desirable objectives have been achieved. However, it should be emphasized that the particular embodiment of the invention which is described herein and illustrated in the accompanying drawings is intended as merely illustrative of the principles of the invention rather than as restrictive of the scope thereof, which is defined by the appended claims.

We claim:

1. A down-hole horizontal slotting tool comprising a support assembly adapted to -be lowered on a wire line into an at least partially liquid-filled well borehole, centering members mounted at spaced positions around said support assembly for movement between extended positions at which they engage the sidewalls ofksaid borehole to resist transverse and rotational movements of said support assembly and retracted positions clear of said sidewalls, and means for moving said centering members between said extended and retracted positions, a motor on said support assembly, a rotor assembly projecting from said support assembly and mechanically coupled to said motor to be rotated thereby about a vertical axis, cutter elements movably mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be immersed in the liquid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate relative to said rotor assembly, and means mechanically coupling said vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction.

2. A down-hole horizontal slotting tool comprising a housing adapted to be lowered on a wire line into an at least partially liquid-filled well borehole, centering members mounted at spaced positions around said housing for radial movement between extended positions at which they engage the sidewalls of said borehole to resist transverse and rotational movements of said housing and retracted positions clear of said sidewall, and means for moving said centering members lbetween said extended and retracted positions, a motor in said housing, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said motor to be rotated thereby about a vertical axis, cutter elements movably mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be immersed in the liquid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate relative to said rotor assembly, means mechanically coupling said vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction, and detent means engaging one of the aforementioned parts movable relative to said rotor assembly to hold said cutter elements normally in a retracted position within the projected line of said housing, said detent means being yieldable to permit movement of said cutters to or from said retracted position under the forces acting upon said cutters during rotation of said rotor assembly.

3. A down-hole horizontal slotting tool comprising a housing adapted to be lowered into a well borehole on a wire line, centering members mounted at spaced positions around said housing for radial movement between ex tended positions at which they engage the sidewalls of said borehole to resist transverse and rotational movements of said housing and retracted positions clear of said sidewall, and means for moving said centering members between said extended and retracted positions, a motor in said housing, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said motor to be rotated thereby about a vertical axis, cutter elements mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, means to urge said cutter elements outwardly into cutting engagement with the sidewalls of said borehole during rotation of said rotor assembly and to retract said cutter elements inwardly for movement of said tool along said borehole, a scriber element mechanically coupled to at least one of said cutter elements for movement therewith, and a malleable element mounted on said rotor assembly in cooperative relation to said scriber element whereby said scriber element will make a mark in said malleable element indicative of the extent of outward movement of said cutter elements.

4. A down-hole horizontal slotting tool comprising a housing adapted to be lowered on a wire line into an at least partially liquid-filled well borehole, centering members mounted at spaced positions around said housing for radial movement between extended positions at which they engage the sidewalls of said borehole to resist transverse and rotational movements of said housing and retracted positions clear of said sidewall, and means for moving said centering members between said extended and retracted positions, a motor in said housing, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said motor to be rotated thereby about a vertical axis, cutter elements movably mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be lmmersed in the liquid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate relative to said rotor assembly, means mechanically coupling said vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction, a stylus and a replaceable soft metal member mounted in cooperative relation, one on said rotor assembly and the other on one of the aforementioned parts movable relative thereto, whereby said stylus will scribe an arcuate line in said soft metal member having an angular length indicative of the extent of outward movement of said cutter elements.

5. A down-hole horizontal slotting tool comprising a housing adapted to be lowered on a wire line into an at least partially liquid-filled well borehole, centering members mounted at spaced positions around said housing for movement between retracted positions adjacent said housing and extended positions in which said centering members engage the sidewall of said `borehole to urge said housing toward a central position in said borehole and to resist rotation ot said housing, rst and second motors in said housing, drive means mechanically connecting said centering members to said first motor for driving said centering members outwardly to said extended position, spring means for returning said centering members to said retracted position upon stopping of said rst motor, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said second motor to be rotated thereby about a vertical axis, cutter elements movably mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be immersed in the liquid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate relative to said rotor assembly, and means mechanically coupling said vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction.

6. A down-hole horizontal slotting tool comprising a housing adapted to be lowered on a wire line into an at least partially liquid-tilled well borehole, centering members mounted at spaced positions around said housing for radial movement between extended positions at which they engage the sidewalls of said borehole to resist transverse and rotational movements of said housing and retracted positions clear of said sidewall, and means for moving sai-d centering members between said extended and retracted positions, a motor in said housing, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said motor to be rotated thereby about a vertical axis, cutter elements pivotally mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be immersed in the uid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate relative `to said rotor assembly, means mechanically coupling said vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction, a stylus and a soft metal sheet mounted in cooperative relation one on said rotor assembly and the other on one of the aforementioned parts movable relative thereto, whereby said stylus will scribe an arcuate line in said soft metal sheet having an angular length indicative of the extent of outward of said cutter elements, and a detent effectively engaging said cut-ter elements and normally holding them in a retracted position within the projected line of said housing, said detent being yieldable to permit movement of said cutters to or from said retracted position under the forces acting upon them during rotation of said rotor assembly.

7. A down-hole horizontal slotting tool comprising a housing adapted to be lowered on a wire line into an at least partially liquid-filled well borehole, centering members mounted at spaced positions around said housing for movement between retracted positions adjacent said housing and extended positions in which said centering members engage the sidewall of said borehole to urge said housing toward a central position in said borehole and to resist rotation of said housing, iirst and second motors in sai-d housing, drive means mechanically linking said rst motor and said centering members whereby said motor drives said centering members between said retracted and extended positions, said drive means including a slipping clutch which slips when said centering members are in firm engagement with said sidewall, a rotor assembly projecting below the lower end of said housing and mechanically coupled to said second motor to be rotated thereby about a vertical axis, cutter elements pivotally mounted at angularly spaced positions on said rotor assembly for movement in a horizontal plane toward and away from said axis, a vane assembly mounted on said `rotor assembly for limited rotational movement relative thereto, vanes on said vane assembly arranged to be immersed in the uid in said borehole to impart a drag against rotation of said vane assembly and urge it to rotate vrelative to said rotor assembly, means mechanically coupling sai-d vane assembly to said cutter elements whereby such relative rotation of said vane assembly causes outward movement of said cutter elements when said rotor assembly is rotated in one direction and inward movement of said cutter elements when said rotor assembly is rotated in the opposite direction, a stylus and a soft metal sheet mounted in cooperative rela-tion one on said rotor assembly and the other on one of the aforementioned parts movable relative thereto, whereby said 20 stylus will scri-be an arcuate line in said soft metal sheet having an angular length indicative of the extent of outward movement of said cutter elements, and a detent effectively engaging said cutter elements and normally holding them in a retracted position within the projected line of said housing, said detent being yieldable to permit movement of said cutters to or from said retracted position under the forces acting upon them during rotation of said rotor assembly.

References Cited by the Examiner UNITED STATES PATENTS Re. 19,281 8/1934 Schroeder 175--292 X 1,358,818 11/1920 Bering l66-55.7 2,280,769 4/1942 Page 166--55.7 X 2,621,898 12/1952 Brodhead 175-292 X 2,879,038 3/1959 Johnson 175-292 X CHARLES E. OCONNELL, Primary Examiner.

JACOB L. NACKENOFF, Examiner.

N. C. BYERS, Assistant Examiner.

Claims (1)

1. A DOWN-HOLE HORIZONTAL SLOTTING TOOL COMPRISING A SUPPORT ASSEMBLY ADAPTED TO BE LOWERED ON A WIRE LINE INTO AN AT LEAST PARTIALLY LIQUID-FILLED WELL BOREHOLE, CENTERING MEMBERS MOUNTED AT SPACED POSITIONS AROUND SAID SUPPORT ASSEMBLY FOR MOVEMENT BETWEEN EXTENDED POSITIONS AT WHICH THEY ENGAGE THE SIDEWALLS OF SAID BOREHOLE TO RESIST TRANSVERSE AND ROTATIONAL MOVEMENTS OF SAID SUPPORT ASSEMBLY AND RETRACTED POSITIONS CLEAR OF SAID SIDEWALLS, AND MEANS FOR MOVING SAID CENTERING MEMBERS BETWEEN SAID EXTENDED AND RETRACTED POSITIONS, A MOTOR ON SAID SUPPORT ASSEMBLY, A ROTOR ASSEMBLY PROJECTING FROM SAID SUPPORT ASSEMBLY AND MECHANICALLY COUPLED TO SAID MOTOR TO BE ROTATED THEREBY ABOUT A VERTICAL AXIS, CUTTER ELEMENTS MOVABLY MOUNTED AT ANGULARLY SPACED POSITIONS ON SAID ROTOR ASSEMBLY FOR MOVEMENT IN A HORIZONTAL PLANE TOWARD AND AWAY FROM SAID AXIS, A VANE ASSEMBLY MOUNTED ON SAID ROTOR ASSEMBLY FOR LIMITED ROTATIONAL MOVEMENT RELATIVE THERETO, VANES ON SAID VANE ASSEMBLY ARRANGED TO BE IMMERSED IN THE LIQUID IN SAID BOREHOLE TO IMPART A DRAG AGAINST ROTATION OF SAID VANE ASSEMBLY AND URGE IT TO ROTATE RELATIVE TO SAID ROTOR ASSEMBLY, AND MEANS MECHANICALLY COUPLING SAID VANE ASSEMBLY TO SAID CUTTER ELEMENTS WHEREBY SUCH RELATIVE ROTATION OF SAID VANE ASSEMBLY CAUSES OUTWARD MOVEMENT OF SAID CUTTER ELEMENTS WHEN SAID ROTOR ASSEMBLY IS ROTATED IN ONE DIRECTION AND INWARD MOVEMENT OF SAID CUTTER ELEMENTS WHEN SAID ROTOR ASSEMBLY IS ROTATED IN THE OPPOSITE DIRECTION.

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