US2671515A - Well bore cleaning scratcher - Google Patents

Description

March 9, 1954 J. E. HA|

WELL BORE CLEANING SCRATCHER 2 Shee`ts-Sheet l Original Filed Nov. 6, 1945 f lllly March 9, 1954 1 E HALL 2,671,515

WELL ORE CLEANING SCRATCHER Original Filed Nov. 6, 1945 2 Sheets-Sheet 2 JNVENToR.

deaf@ E /yd/ Patented Mar. 9, 1954 UNITED STATES PATENT OFFICE November 6, 1945.

This application October 20, 1948, Serial No. 55,619

3 Claims.

This invention relates-to improvements in well bore cleaningscratchers and relates more particularly to abrading devices adapted to be attached to the exterior surface of casing lowered into an oil well for removing residual mud from the wall of the well bore. Scratchers usually are employed preparatory to cementing a well or for assuring a maximum flow from the production zone ofthe well.

This a continuation of my co-pending application Serial No. 627,013, led November 6, 1945, which in turn was a continuation-in-part of my application ySerial No. 388,891, led April 16, 1941, both of said applications being now abandoned.

An object ofthe invention is to provide scratchers having a plurality of scratching or abrasive elements such as wires projecting outwardly from the body or anchoring collar and responsive to shifting of the casing to which they are attached to displace accumulated residual mud from the surrounding wall of the well.

Another object of the invention is to provide a simple and readily assembled structure with the scratching elements securely and flexibly mounted to the body portion and adapted for tensioned swinging adjustment with reciprocation of the casing to which they are attached.

Still another object of theinventionis to provide coil'spring mountings for the wire scratching elements adjacent to their attachment to the body member so distortion or flexing of the springs is avoided during their reciprocation up and down the well bore.

A further object is the provision of collars or annular supports which form anchoring members for` the whiskers and are rotatably mounted on the casing at different locations along its length, the whiskers being resiliently attached to the collars with their free ends extending outwardly in a manner so as to conform to and press against the wall of the surrounding well bore for abrasive engagement therewith, without distortion along the lengths of Athe scratching elements such as might break or permanently bend the same, the elements engaging the formation at an angle due totheir combined circumferential and axial inclination permitting swinging of the scratching elements and rotation of the scratcher on the well string.

Other and further objects will appear from the following description.

In the accompanying drawings which form a partof the specication andv are to be read in conjunction therewith and in which like reference-,numeralsarelused toLindicate like parts in the-various; views,

Fig. 1 is a side elevational view showing, a scratcher embodyingthe invention mounted ona well string, part of the scratcher being broken away to show the method of anchoring thev wire whiskers, the whiskers shown in dottedlines illus.- trating the manner in which they are tensioned in the well bore,

Fig. 2 is a transverse section taken on the` line 2 2 in Fig. l in the direction of the-arrows,

Fig. 3 is an elevational view.similar.toFig. 1 showing a scratcher in which the whiskers are anchored to the collar` or sleeve.in, a .di1ferent manner,

Fig. 4 is a view similar to` Fig. 1 showing,v a modied type of scratcher for closer tolerances between the scratcher andthe wellfbore,

Fig. 5 is a top half View ofthe scratchershown in Fig. 4, and

Fig. 6 is an enlarged section of the coil lmount-,- ings employed in the close tolerance type scratcher shown in Figs. 4 and 5.

Well cleaning scratchers haverbeen used heretofore where the whiskers or abrading ,wires were rigidly attachedor anchored tothe bodygrnember or collar. Coil mountings have been made in which the axis ofthe wires were parallel tothe coil mountings. Fixed orrigid attachment'of the wires to the collars or` sleeves is` unsatisfactory because reciprocation of the well stringor` drill pipe to which the scratchers are attachedv during the cleaning operation distorts and-deforms the wires, soon rendering them ineffective. Another objection to rigid anchoring of the wires is the difficulty encountered in reciprocating the casing or well string due to the fact that the wires or whiskers fail to change direction rapidly` enough with the reciprocation of the casing. Asf a-result, to extricate the string an immense amount of pull or force must be imposed on the draw works and in deep holes frictional resistance and the weight of the string may prevent removal of the string. Abrading wires whoseaxesf are parallel to the coil mountings have been used only as perforation cleaners and lacktheaexibility and effectiveness of wire whiskers which extend at an angle from their mountingcoils..

Where the wires are arranged in the manner shown, and in. contact. with the well .bore reciprocation of the casing causes the wires to fulcrum at their coils. With the'coilsgactingv as fulcrums, and the free ends ofthewires pivoted at the rwell boreby -frictional contact therewith,

reciprocation of the casing-causes theabrading wires to walk around the-'innersurface'V of!v the well bore rotating its sleeveA uponithe;l casing. Thusfeach wire renews its abradingaetion :within the bore hole at a different location. In other words, the flexible spring mountings and the manner of extending the Wires from the annulus or collar inclined in a circumferential direction relative to radii of the collar and well string cause the whiskers to change their position with reciprocation of the string, thereby preventing a channeled course to be followed by the individual wires.

Referring to the drawings and particularly to the rst three figures, to the casing I at intervals along its length are positioned the scratchers which comprise a cylindrical collar or sleeve I I. Welded to the casing or drill pipe above and below the collar II are lugs or abutments I 2. 'I'he collars being loosely tted along the casing are free to rotate and have -a limited axial movement between the lugs. The collars are preferably fianged at their upper and lower edges to improve their strength along the margins. Centrally of the collars are a plurality of rivets I3. Above 4and below the row of rivets are rows of holes whose centers are preferably staggered so none of the holes fall in axial alignment. Both the upper and lower rows of holes in the collars 0r anchoring sleeves are designated by the numeral IIa.

Attached at their inner ends to rivets I3 within the sleeves or collars are resilient wires or whiskers I4, the fastened ends of the wires encircling the rivets to anchor the ends of the wires rigidly to the collar as shown in Figs. 1 and 2. Two whiskers are preferably attached to each rivet one of which passes through a hole in the upper row and the other through an adjacent hole in the lower row. The projecting free ends of the abrading wires or whiskers extend from the outer surface of the collar at an acute angle with the extension of the radius of the collar passing through the projection point of the particular wire. The manner in which they radiate from the surface of the anchoring sleeve is perhaps best shown in Figs. 2 and 4. It is this unusual arrangement of the whiskers which produces rotation of the collar and migration of the ends of the wires about the well bore upon reciprocation of the casing. This action results in a much more effective cleaning of the well bore.

Intermediate the fastened and free ends of the abrading wires or whiskers and located within the holes I Ia of the collar or sleeve I I are formed coils Illa which impart iiexibility and resiliency to the mounting of the whiskers on the collar. 'I'hese coil springs, besides giving resiliency to the mounting of the whiskers in the collar, permit relatively free or universal tensioning and rotation of the whiskers during reciprocation of the string. These outwardly projecting scratching elements normally define a diameter somewhat greater than the bore of the well shown at I5, so with the scratchers mounted on the well string and the string lowered into the well the scratching elements are swung upwardly and are tensioned in position with their outer ends pressing against the wall of the surrounding well bore as shown by the dotted line position in Figs. 1 and 4. When the string of the casing is axially shifted or reciprocated, the outer ends of the scratching elements having abrasive contact with the wall surrounding the well bore displace residual mud adhering thereto. The outwardly projecting wires are substantially rigid along their length so reciprocation produces no considerable iiexure, but a swinging movement ful- 4 I crumed at their coil spring mountings. The coil springs, in addition, permit swinging rotation of the wires so that the scratching elements may be rotated in any direction While the coil springs keep tensioned engagement of the scratching elements against the wall without more than the necessary friction to abrade adhering mud. It will be seen that Whether the string be rotated or reciprocated the coil spring mounting permits the wire to immediately shift direction and follow the movement of the casing string. Regardless of the movement, the coil spring tension upon the Wires tends to return the abrading whiskers to their normal outwardly projecting position irrespective of the direction in which they may have been swung.

Each scratching element, as has been suggested, has a wire coiled intermediate its ends with the coil positioned in a hole in the anchoring sleeve. The freevend of the wire projects substantially from the axis of the coil. The scratching elements are preferably arranged in two rows spaced axially above and below a central row of rivets I3. The holes in the anchoring sleeve and the scratching elements which extend through the holes are preferably staggered circumferentially of the collar with all of the scratching elements preferably inclined rearwardly with relation to direction of rotation indicated by the arrow A.

In the modification shown in Fig. 3 the ends of the abrading wires I4 attached to collar II are bent around steel pins or pegs I6 Within the collar which take the place of the rivet fastenings shown at I3 in Fig. 1. In this modification as in the forms shown in Figs. 1 and 2, wire coils Ida. allow the abrading wires radial or axial tensioning permitting substantially universal movement of the free ends of the scratching elements while fulcrumed at the coils. Each coil in both forms comprises a sufficient number of loops to provide the desired resiliency whereby its scratching element may be swung through appreciable arcs which have the coils as centers.

In the construction shown in Figs. 4, 5 and 6, the loops of the coils which were of the same diameter in the scratcher shown in Figs. 1, 2 and 3 are replaced by coils having loops increasing in diameter from the inner to the outer end of the coils best shown in Fig. 6. Note too that the inner loops of largest diameter are Within the sleeve while the smaller loops are located in the holes in the sleeves. These conical shaped coils are designated by the numeral I 4b. The inner or fastened ends of the wires are, as before, wrapped around the studs or rivets I3. Flattened ends on the rivets prevent the wires from slipping off. The advantage of the cone shaped coils over the cylindrical coils shown in the previous form is that they permit operation of the scratchers where close tolerances exist between the casing and the well bore. In other words, coil mountings of decreasing diameter with the large inner coils conned within the sleeve permit substantially universal exing of the abrading wires without exposing any substantial part of the coil springs outside the surface of the anchoring sleeve.

As clearly shown in the drawings, in all of the above embodiments and modifications each wire abrading element extends from a different point on the periphery of the collar at an angular inclination with a Aplane which includes both the radius of the collar to the projection point of the particular element andthe axis of the co1- lar and well string. In other words, each abrading element extends at an angular inclination havingsidewise direction to the radius of the support or collar drawn to said projection point and all of the elements being in substantially the Vsame angular relation with the support.

The assembly and angular association of the abrading elements with the annular support or collar, together with the rotatable mountingr of thel collar on the casing causes the collar to rotate upon reciprocation of the casing, thereby relieving bending stress imposed upon the abrading elements by said reciprocation and shifting said elements circumferentially within the well bore.

To permit convenient assembly of the scratchers upon the casing or drill pipe the anchoring sleeves or collars may be split axially in order that they may be wrapped around the casing and then welded together, thus avoiding the necessity of slipping the sleeve over the ends of the casing sections to theiry proper location along the string. The scratchers in the form of axially split annuluses are assembled along the well string between the abutments or lugs l2. Any number of scratchers may be mounted in spaced relation along the well string.

One purpose for which the wall cleaning scratchers are particularly adapted is their use with centralizers on casing in obtaining a permanently satisfactory cement job. Important in this regard is the fact that scratchers of this type are reversible in a hole much smaller than their overall diameters. This enables the operator to run scratchers with an overall bristle spread sufciently larger than the drilled diameter of the hole to conform with the well walls and clean holes of an irregular shape up and down its length. Layers of jelled mud, mud cake, and cuttings are cleaned from the crevices and cavities along the well bore permitting the cement to bond directly to the formation.

In addition to their use on the casing, the scratchers may be used on drill pipe or tubing for cement plug back jobs, on gravel liners to aid in a formation washing operation, on drill pipe or hole conditioning jobs, on bailers for bottom hole plug back jobs, or on the casing string for conditioning the walls of the hole.

When the casing is properly centralized this type scratcher produces complete scratching coverage since the unique mechanical operation during the reversing process causes them to crawl and walk around the hole. The spring mountings of the scratchers, due to rotation of the sleeves, change their position on the wall of the well with each reciprocation. This walking of the wires around the hole and rotation of the collars prevents the abrading ends of the whiskers from tracking up and down in the same place in the hole, thus providing complete coverage of the inner wall surface. The unusual mechanical action of the abrading wires has been determined by mounting a scratcher on -a piece of pipe and reciprocating it within a pipe of larger diameter. As the scratcher is being run in a dummy oil well of this sort it has been noted that the whiskers are lpointed upwardly in the same direction as the scratcher is lowered into the pipe. As the direction of the scratcher is reversed, the free ends of the wires hold their position against the inside of the pipe or well bore as they are rotated upon their coil springs as fulcrums. As

the wires rotate in arcs passing from a relatively nates the dead thrust action longitudinally of the wires vwhich is present when the sleeve is fixed on'the casing and the wires are rigidly attached tothe sleeve. Also, the angle at which the wires extend from the sleeve permits free rotation of the wires about the coils as centers, eliminating Yundue friction,.dis tortion and buckling 'of thel wires within the annular space between the wellwallrand casing. Furthermore, if the Wires extended radially the pipe would act as. a rigid stop at the inner ends 0f the wires requiring the wires to bend or vflex at an inter-- mediate point as the directionvof the scratcher is reversed. i

When mounted in the manner shown as the direction of the scratcher is reversed the free ends ofthe-wires travel or crawlaround the surface of the well hole following the pattern described. Thus the importance of the resilient spring mountings and the direction in ywhich the free ends of the wires extend from the surface of the sleeve will be readily appreciated.

From the foregoing it will be seen that the scratchers are well adapted to attain the ends and objects herein above set forth together with other advantages which are obvious and are inherent to their structure.

It will be understood that certain features and subcombinations 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.

Having thus described the invention, I claim:

l. In combination with a well casing, a support rotatably mounted on the exterior of said casing, stiff wire whiskers each exibly attached at one end to said support and each projecting from a point on the periphery of the support at an angular inclination having sidewise direction with respect to the radius of the support drawn to said projection point of the particular whisker, and all in substantially the same angular relation with the support.

2. In well cleaning equipment, a casing reciprocable in the bore of a well, a support rotatably mounted on the exterior of said casing, stiff wire whiskers each flexibly attached at one end to said support, and each projecting from a point on the periphery of the support at an angular inclination having sidewise direction with respect to the radius of the support drawn to said projection point of the particular Whisker and all in substantially the same angular relation with the support, the free ends of said whiskers being of a length to frictionally contact the well wall and abrade its surface upon reciprocation of the casing, said whiskers upwardly inclined on the downstroke and downwardly inclined on the upstroke of the casing and upon reversal of the casing travel adapted to fulcrum both at their points of contact with the well wall and substantially at their points of attachment with the support whereby vertical movement of the casing after each reversal rotates the support on the casing, thereby relieving bending stress on the whiskers and shifting the whiskers circumferentially upon the well bore to contact and abrade a different area upon each casing reciprocation.

3. A well bore cleaning scratcher adapted to be rotatably mounted on a Well casing comprising an annular support, sti Wire whiskers, each flexibly attached at one end to said support and each projecting from a point on the periphery of the support at an angular inclination having sidewise direction with respect to the radius drawn to said projection point of the particular Whisker and all of said whiskers projecting in substantially the same angular relation from said support.

JESSE E. HALL.

References Cited in the le f this patent UNITED STATES PATENTS Number Name Date 1,217,763 Hirrich Feb. 27, 1917 1,342,618 Bashara June 8, 1920 1,371,425 Jones Mar. 15, 1921 1,423,625 Rogers July 25, 1922 1,553,813 Griin Sept. 15, 1925 1,758,995 Armstrong et al. May 20, 1930 2,151,416 Black et al Mar. 21, 1939 2,157,493 Miller et al. May 9, 1939 2,248,160 Crawford July 8, 1941 2,258,052 Hall Oct. 7, 1941 OTHER REFERENCES Oil and Gas Journal, September 11, 1941, page 65.

The Oil Weekly, July 7, 1941, page 37, vol. 102, No. 5.

The Oil Weekly, March 11, 1940, page 45.

The Oil Weekly, March 25, 1940, pages 46, 47,

Petroleum World, June 1940, pages 26-30, 32, 34, 35, 42, 57-59.

Oil Well Cementing Factors Influencing Bond between Cement and Formation, by P. H. Jones and Denis Berdine, March 19, 1940.

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