US3071191A - Close tolerance scratchers - Google Patents

Description

Jan. l, 1963 J. E. HALL, sR., ETAL 3,071,191

cLosE TQLERANCE scRATcHERs Filed Nov. 20. 1959 2 Sheets-Sheet 1 Ill /2 3. 0 @D INVENToRj. desse i bla/4 .6/2 ese/f A. a/Yey Jan. l, 1963 J. E. HALL, SR., ETAL 3,071,19

CLOSE TOLERANCE SCRATCI-IERS Filed NOV. 20. 1959 2 Sheets-Sheet 2 IN1/mfom. deff@ .E ha@ 5f? wir 6.

Unite States Patent Oiitice 3,671,191 Patented Jan. 1, 1963 3,071,191 CLSE TLERANQE SCRATCHERS .lesse E. Hall, Sr., and Lester A. Bailey, Weatherford, Tex.,

assignors to Abasteeedora Jefe, SA., Panama, Republic of Panama, a corporation of Panama Filed Nov. Ztl, 1959, Ser. No. 854,292 2 Claims. (1. 165-173) This invention relates to well bore scratchers of the circular band or collar type utilizing angularly disposed wire abrading elements and adapted to be mounted on the exterior of a tubular casing and reciprocated therewith in a well bore. The invention refers more particularly to such a scratcber `designed and adapted to fit into relatively small diameter well bores where there is a minimum distance or annulus between the well bore and the outer surface of the casing.

This invention is an improvement over the structure shown in the Hall, Sr., Patent 2,735,495, issued February 21, 1956, for Well Bore Scratcher.

Salient features of novelty of the instant invention reside in the manner of fastening the wire abrading elements to the collar, the type and arrangement of coil springs Wound into the wire abrading elements, `and the construction of the wall of the collar itself whereby to protect in the most effective manner the coil springs in operation of the scratcher and, additionally, achieve a maximum rigidity and strength in the collar, while providing a minimum thickness thereof.

A major problem in well conditioning preparatory to cementing where scratchers are used is the reduction of the thickness of the scratcher collar whereby to minimize the obstmction and hindrance presented to the passage of mud or circulated well fluid in the annulus between the casing and Well bore. In tight holes, where such annulus is narrow, a condition often referred to as close tolerance exists and the thicknes of the scratcher collar is of vital importance to the success of the operation. A factor critical to operation of any collar type scratcher utilizing wire abrading elements is the capability of the scratcher `collar to move through the plane of engagement of the wire ends with the well bore wall upon reversal of direction of movement of the casing during reciprocation without hanging or fouling of the wires in the coil springs of adjacent wires occurring. The latter problem is particularly critical in close tolerance situations.

The art encompasses the scratcher of Hall, Sr., as exemplified in United States Patent No. 2,671,515, issued March 9, 1954, yfor Well Bore Cleaning Scratcher in addition to the Hall Patent No. 2,735,495, previously noted. Other various efforts at close tolerance scratchers to enable scratchers to be used in decreased diameter holes, particular `at great depths are `also known. it should be noted that a number of critical objections arise when considering the Hall scratcher of Patent No. 2,671,515 in relation to close tolerance holes. In the first place, in a uniform diameter coil spring, at least .three or four convolutions or wraps are required to permit the required up and `down travel of the free wire ends with suitable resilience of the tines. This number of wraps requires quite a thick collar to provide any protection whatsoever. However, even with the thick coHar, when the tines are bent toward the collar, the wraps or coils rise up above the surface of the collar and permit snagging of the coils with adjacent tines or rubbing off of the coils against the Well bore, etc. Additionally, the uniform diameter Wraps or :coils require a quite complex engaging structure interiorly of the collar including a U-bend in the center portion thereof between coils with at least three lances engaging the center portion. This latter construction prevents layover of the coils on reversal of rotation of the scratcher in the Well. Referring generally to the art, helical springs are sometimes employed, but are always inadequate because of their inherent ability to handle both winding and unwinding action. In the unwinding action the coil above will get larger and expand to the adjacent coil and lose etliciency of resilient action. Since the helical spring is in contact with the next lower wrap or coil, the tendency is to break off the tine. Additionally, the tightness of `the last winding (top winding or coil) tends to permit and produce snapping oif of the tine.

Therefore, an object of the invention is to provide a close tolerance seratcher wherein a minimum of excessive diameter extension is created when the tine lays down on the collar.

Another object of the invention is to provide a close tolerance scratcher with more resilience in the tines than one having uniform `diameter wraps.

Another object of the invention is to provide `a close tolerance scratcher with an absolute minimum of engagement required interiorly of the collar of the abrading wire units, yet wherein a `bracing action is provided against circumferential reversing of the wires.

Another object of the invention is to provide a close tolerance scratcher with secure internal engagement of the wires yet a minimum thickness of the collar produced by said engagement.

Yet another object of the invention is to provide a close tolerance scratcher with equal resilience, strength and reversability compared to the uniform diameter wrap or coil type scratcher of the Hall Patent No. 2,671,515, yet with no coil extension beyond the `collar or coil rub-olf potential.

Another object of the invention is, in well bore scratchers, to reduce to a minimum the thicknes of the scratcher collar and the operating thickness of the entire scratcher assembly by providing a coil spring structure which, while providing the necessary and desired flexibility to the abrading wires, at the same time restricts within the most narrow limits the height of the spring coils and their projection above the peripheral surface of the collar.

Another object of the invention is to provide new methods and means of attaching the wires to the interior of the `collar which provides a secure, long lasting, cheap, easy to manufacture attachment, while, at the same time, minimizing the thickness of the collar.

Another object of the invention is to provide a minimum thickness scratcher collar construction which nevertheless protects the coil springs from the reversing motion of the abrading wires to the maximum extent in operation of the scratcher on a reciprocating casing in the well bore.

Other and further objects of the invention will appear in the course of the following description thereof.

In the drawings, which form Ia part of the instant specification and 4are to be read in conjunction therewith, embodiments of the invention are shown and, in the various views, like numerals are employed to indicate like parts.

FIG. l is an end on, axial view of a scratcher embodying a iirst preferred form of the inventive construction.

FIG. 2 is a side elevation, with parts cut away and in section to better illustrate the scratcher construction of the construction of FIG. 1.

FIG. 3 is a View ta'ken along the line 3 3 of FIG. 2 in the direction of the arrows.

FIG. 4 is a view taken along the line 4-4 of FIG. 2 inthe direction of the arrows.

FIG. 5 is an enlarged perspective detail of a scratcher wire unit adapted to be mounted upon the inside of the collar of the inventive scratcher.

FIG. 6 is an end on axial view of a scratcher embodying a second form of the inventive construction.

FIG. 7 is a side elevation, parts cut away and in section, of a portion of a second form of the inventive construction.

FIG. 8 is a View taken along the line 7-7 of FIG. 7 in the direction of the arrows.

FIG. 9 is a view taken along the line 9-9 of FIG. 7 in the direction of the arrows.

FIG. l is a fragmentary interior perspective of the scratcher band of FIG. 6 without attachments.

Referring to the drawings and particularly to the preferred modification of FIGS. 1e5, inclusive, at 10` is generally designated a band or collar which serves as a support for abrading wire units of FIG. designated as a whole by the numeral lll. These units comprise free end portions 11a, coil springs 11b for inside collar band attachment, coil springs 11e for outside collar attachment and cross-over portions llld by means of which the wire units are fixed to the collar, whether the units are mounted within the collar or outside the collar. FIG. 2 shows the assembled unit, with the coil springs 11b located in aperture 10a punched in the collar.

The abrading wire unit construction as shown in FIG. 5 comprises a single enlarged partial coil or convolution of relatively large diameter at the bottom of the coil, surmounting and contained within this large partial loop at least two loops or convolutions of wire of smaller internal diameter than the large convolutions but substantially the same internal diameter amongst themselves. From the upper convolution of each of the coil springs extend the free ends 11a. The coils of relatively smaller diameter and the free ends 11a are not inclined with respect to the axis of any one of the lesser diameter coils, but the entire assembly is inclined with respect to the larger diameter base coils 11b as seen in FIG. 4. Cross-over portions 11d extend between the larger partial coils 11b substantially at a diametric position intermediate therebetween. In the construction of FIG. 2, the diameter of the larger partial coils 11b is greater than the inside diameter of openings lila, while the outer diameter of the larger partial coils 1lb is greater than the inside diameter of openings 10a, while the outer diameter of the smaller coils llc is less than the openings 10a inside diameter. Thus the inner partial large coils may lie circumferential to said openings with the smaller coils extending thereinto and therethrough.

The collar 10 has a circumferential groove 10b indented or formed inwardly therein preferably centrally thereof or intermediate the openings 10a, the latter paired opposite one another at upper and lower portions of the collar. Upper and lower grooves or ribs 10c are formed in the upper and lower edges of the collar and are of greater depth than the center groove or rib 10b. The outer diameter of the extreme upper and lower edges of the collar are less than the outer diameter of the collar portions which are not grooved or ribbed. Secondary grooves or openings 10d are formed, cut or punched in the central rib or groove 10b between openings ltla to receive the cross-over wire portions lid. The edges or walls of the openings 10d are punched, pressed or formed inwardly over the cross-over portions after the insertion of the latter therein to x the wire units to the collar.

Referring particularly to FIG. 4, raised portions or dimples 12 are outwardly formed, attached to or otherwise provided along a portion of the periphery of openings 10a in a direction opposite the extension of the end portions 11a in their normal direction of extension. The raised portions 12 are limited in extent to the maximum of one-quarter the circumferential distance of the openings 10a. In a case of a three coil central spring as shown in the figures, the following relationships accrue. The thickness of the partial large coils 1lb is substantially the depth of the inwardly formed rib or groove 10b. The first coil of the lesser diameter spring portion is substantially received within the said larger partial coil. The second coil of the lesser diameter spring portion is received within the thickness of the collar itself circumferential to the openings 10a. The third and final coil is substantially received within and matched by the thickness of the outwardly formed or dimpled portions 12. In the case of a two complete coil lesser diameter spring, even lesser extension of the wire units relative t-o the collar is achieved and thus this form is optimum.

It should be noted that the triple grooving or ridging of the collar as exemplified at 10b and 10c provides an exceedingly strong and rigid, though exceedingly narrow collar with full protection to each segment of the wire unit on each side of the central ridge. This is an advantage not previously achieved.

It should be appreciated that the scratchers as illustrated, are mounted at intervals along the length of casing or pipe and so located as to clean the bore of the well of accumulated mud where a cement column is to be placed. The annulus between the casing and well bore being relatively narrow, causes the free ends or abrading wires lla to drag against the well wall and bend upwardly as the casing is run into the hole or during the downstroke when reciprocated. On the upward movement of the casing, since the scratchers are mounted upon the casing between stops, the movement of the free ends of the wires are reversed, at which time the scratcher collars must pass through the wires as they are closely wrapped about the collar due to the narrow space within which they operate. If prominences or projections of any sort, such as the tops of the coil springs, extend beyond the outer surfaces of the scratchers and are not protected, the free ends of the wires are apt to hang upon these projections, thus fouling the wires upon the springs and, in some instances, carrying them' from their attachment to the collar. When this occurs, the effectiveness of the abrading wires and scratchers is materially reduced. It is for this reason that, in the constructions shown in FIGS. l-5, and in the modified structures of FIGS. 6-10, the Wire units are attached to the collar by an inside mounting, the height of the coil springs, carefully regulated and reduced to a minimum, and outward indentations E2 are provided. Guard members l2 are provided particularly to permit the abrad-l ing ends of the wires to pass freely over the surface of the collar and prevent hanging or fouling of the wires with the coils.

With the provision of the partial large convolution of FIG. 5, it has been found that three full lesser diameter convolutions are sufficient, although essential, in the coil springs to provide the required resiliency and reversability of the free ends of the wires during reciprocation. This is a marked improvement over the construction of the Hall Patent No. 2,735,495, which projected a minimum of four convolutions with at least one full convolution in the larger internal coil. Even when four convolutions are employed in the instant construction, with only the partial -convolution present in the large internal construction, yet a marked reduced width or thickness of the wire unit is achieved.

Referring to FIGS. 6-10, inclusive, therein is shown a construction identical in all ways to that of FIGS. l-S, inclusive, with the exception of the method of attachment of the cross-over portions to tr e central ridge or groove. Thus, identical parts in FIGS. 6-10 to FIGS. 1-5 have been numbered the same, but primed.

Referring then to FIGS. 6-10, inclusive, and the novelty therein, secondary grooves r3 are formed in ridge or groove 10b whereby to receive cross-over portions lld. A circumferential band of metal is then fixed by welding or other means of attachment to the ridge or groove lltb in such fashion as to rigidly x the cross-over portions 11d in the secondary grooves 13. The thickness of the band 14 is preferably a minimum and is partially compensated for by the greater inward extension of ridges or grooves c' of collar 10 over ridge or groove 10b. Band 14 also protects the cross-over portions to a greater extent, although requiring a slightly greater total thickness of the collar. If the band is of sufficient width to overlie some portion of the enlarged partial coils 11b', it aids in rigidifying these coils against layover during reversal of rotation of the scratcher on the pipe.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinaions are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention Without departing from the scope thereof, it is to be -understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, We claim:

l. In a well bore scratcher, the combination with a circular collar band support adapted to be tted over `a casing, said collar band support having a plurality of paired openings therethrough disposed circumferentially thereof, of a plurality of wire abrading units attached to the collar, said units each comprising a central straight cross-over Iportion disposed against the collar and extending between a pair of said openings, an enlarged partial coil of greater than 180 and less than 360 arc wound into the wire at the extremities of the `cross-over portion, each said enlarged partial coil disposed llat against the collar and of greater diameter than said openings, no more than three lesser diameter full coil springs wound into the wire at the extremity of the larger coil and of such diameter as to lit into said openings, the inner one of said lesser diameter coils fully received within the larger diameter partial coil, said `cross-over portion extending between said larger partial coils substantially at a diametric position intermediate therebetween, the said cross-over portions and enlarged partial coils of said wire units lying against the interior surface of the collar with the lesser diameter coils positioned in the openings in said collar, said wire units being attached to said collar by means engaging said cross-over portion, said means engaging said cross-over portion comprising a groove circumferentially formed centrally of said collar with the wall thereof extending inwardly ofthe collar, said circumferential groove wall having a secondary groove formed therein to receive each cross-over portion, and a circumferential metal ring fixed interiorly of said band to said groove wall and overlying said cross-over portions, and a freel end portion projecting from each of the said respective smaller diameter coil springs outwardly away from the outside surface of the collar.

2. In a well bore scratcher, the combination with a circular collar band support adapted to be fitted over a casing, said collar band support having a plurality of paired openings therethrough disposed circumferentially thereof, of a plurality of wire .abrading units attached to the collar, said units each comprising a central straight cross-over portion disposed against the collar and extending between a pair of said openings, an enlarged partial coil of greater than and less than 360 arc wound into the Wire at the extremities of the cross-over portion, each -said enlarged partial coil disposed flat against the collar and of greater diameter than said openings, no more than three lesser `diameter full coil springs Wound into the wire at the extremity of the larger coil and of such diameter as to t into said openings, the inner one of said lesser diameter coils fully received within the larger diameter partial coil, said cross-over portion extending between said larger partial coils substantially at a diametric position intermediate therebetween, the said cross-over portions and enlarged partial coils of said wire units lying against the interior surface of the collar with the lesser diameter coils positioned in the openings in said collar, said wire units being attached to said collar by means engaging said cross-over portion, said means engaging said cross-over portions comprising a circu-mferential groove formed in said collar with the wall thereof extending inwardiy of the collar, said circumferential groove wall having a secondary groove formed therein to receive each cross-over portion of said wire units, the portions of said ygroove wall next to said secondary grooves formed over said cross-over portions in such manner `as to positively engage them and attach the wire units to said collar.

References Cited in the le of this patent UNITED STATES PATENTS 2,735,495 Hall Feb. 2'1, 1956 2,808,112 Hall Oct. l, 1957

Claims (1)

1. IN A WELL BORE SCRATCHER, THE COMBINATION WITH A CIRCULAR COLLAR BAND SUPPORT ADAPTED TO BE FITTED OVER A CASING, SAID COLLAR BAND SUPPORT HAVING A PLURALITY OF PAIRED OPENINGS THERETHROUGH DISPOSED CIRCUMFERENTIALLY THEREOF, OF A PLURALITY OF WIRE ABRADING UNITS ATTACHED TO THE COLLAR, SAID UNITS EACH COMPRISING A CENTRAL STRAIGHT CROSS-OVER PORTION DISPOSED AGAINST THE COLLAR AND EXTENDING BETWEEN A PAIR OF SAID OPENINGS, AN ENLARGED PARTIAL COIL OF GREATER THAN 180* AND LESS THAN 360* ARC WOUND INTO THE WIRE AT THE EXTREMITIES OF THE CROSS-OVER PORTION, EACH SAID ENLARGED PARTIAL COIL DISPOSED FLAT AGAINST THE COLLAR AND OF GREATER DIAMETER THAN SAID OPENINGS, NO MORE THAN THREE LESSER DIAMETER FULL COIL SPRINGS WOUND INTO THE WIRE AT THE EXTREMITY OF THE LARGER COIL AND OF SUCH DIAMETER AS TO FIT INTO SAID OPENINGS, THE INNER ONE OF SAID LESSER DIAMETER COILS FULLY RECEIVED WITHIN THE LARGER DIAMETER PARTIAL COIL, SAID CROSS-OVER PORTION EXTENDING BETWEEN SAID LARGER PARTIAL COILS SUBSTANTIALLY AT A DIAMETRIC POSITION INTERMEDIATE THEREBETWEEN, THE SAID CROSS-OVER PORTIONS AND ENLARGED PARTIAL COILS OF SAID WIRE UNITS LYING AGAINST THE INTERIOR SURFACE OF THE COLLAR WITH THE LESSER DIAMETER COILS POSITIONED IN THE OPENINGS IN SAID COLLAR, SAID WIRE UNITS BEING ATTACHED TO SAID COLLAR BY MEANS ENGAGING SAID CROSS-OVER PORTION, SAID MEANS ENGAGING SAID CROSS-OVER PORTION COMPRISING A GROOVE CIRCUMFERENTIALLY FORMED CENTRALLY OF SAID COLLAR WITH THE WALL THEREOF EXTENDING INWARDLY OF THE COLLAR, SAID CIRCUMFERENTIAL GROOVE WALL HAVING A SECONDARY GROOVE FORMED THEREIN TO RECEIVE EACH CROSS-OVER PORTION, AND A CIRCUMFERENTIAL METAL RING FIXED INTERIORLY OF SAID BAND TO SAID GROOVE WALL AND OVERLYING SAID CROSS-OVER PORTIONS, AND A FREE END PORTION PROJECTING FROM EACH OF THE SAID RESPECTIVE SMALLER DIAMETER COIL SPRINGS OUTWARDLY AWAY FROM THE OUTSIDE SURFACE OF THE COLLAR.

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