US2683491A - Scratcher for well bores - Google Patents

Description

y 1954 .1. s. GASSAWAY SCRATCHER FOR WELL BORES 2 Sheets-Sheet 1 Filed June 1 1951 INVENTOR.

w m s 6 5 B M y 1954 J. 5. GASSAWAY 2,683,491

SCRATCHER FOR WELL BORES Filed June 1, 1951 2 Sheets-Sheet 2 1N VEN TOR.

ATTORNEYS Patented July 13, 1954 UNITED STATES PATENT OFFICE SCRATCHER FOR WELL BORES Application June 1, 1951, Serial No. 229,360

13 Claims. 1

The present invention relates to subsurface well tools, and more particularly to devices for scratching or scraping the walls of open well bores, conduits of various kinds disposed in well bores, and the like.

An object of the present invention is to provide improved scratcher devices that are capable of effectively removing mud cakes and other undesired substances from the walls of well bores and well conduits disposed in well bores.

Another object of the invention is to provide scratcher devices embodying wall engaging spring elements that can be assembled with facility on their supporting members, and with the employment of a minimum number of parts and operations.

A further object of the invention is to provide a scratcher device that lends itself to production through the use of automatically operating equip- P1191117, thereby decreasing substantially the cost of manufacturing the devices and the time consumed in producing them.

Yet another object of the invention is to provide scratcher devices embodying wall engaging spring elements and supporting members therefor, in which the spring elements and supporting members maintain themselves in appropriate assembled relation with respect to each other, without the need for any other parts or materials.

Still a further object of the invention is to provide a scratcher device embodying wall engaging spring elements that can contain more spring coils, thereby making the elements more flexible for the performance of their well scratching function, and less susceptible to permanent distortion.

Another object of the invention is to provide a scratcher device for use in a well bore that is of stronger and sturdier construction, and in which the looseness or play between the spring elements and their supporting member can be varied, and, if desired, substantially completely eliminated.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined 'by the appended claims.

Referring to the drawings;

Figure l is a side elevation of a wall scratcher mounted on a casing section, with parts being disclosed in longitudinal section;

Fig. 2 is a cross-section taken along the line 2-4 on Fig. 1;

Fig. 3 is a somewhat diagrammatic view of a wall scratcher mounted on a casing string during lowering of the latter in a well bore;

Fig. 4 is a view similar to Fig. 3, disclosing elevation of the casing string and scratcher in the well bore;

Fig. 5 is an enlarged plan view of a portion of a wall scratcher device prior to complete assembly of the scratcher elements on their supporting collar or sleeve;

Fig. 6 is an enlarged fragmentary section taken along the line 66 on Fig. 5;

Fig. '7 is an enlarged fragmentary section taken along the line l'! on Fig. 5;

Fig. 8 is a plan view of one of the scratcher elements;

Fig. 9 is a rear elevation, disclosing the mounting of one of the scratcher elements in the supporting member or sleeve.

As disclosed in the drawings, a Wall scratcher A is mounted on a casing section B, for the purpose of removing the mud cake C from a portion of a well bore D in which the casing string is to be disposed, and also to center the casing string in the well bore. The scratcher has the primary purpose of removing the mud cake or sheath C from a particular portion of the well bore, in order to insure a proper bond between the formation wall and cement slurry, or other cementitious material, pumped down the casing string B for upward passage through the annulus E around the latter. It is preferred not to disturb the mud cake in the well bore to any substantial extent, except along that portion of the formation wall at which the cementitious material is to be disposed. For that reason, the wall scratcher A should engage the mud cake lightly, if at all, during descent of the casing string through the well bore. However, the scratching effectiveness should be at a maximum during upward movement of the scratcher in the well bore.

The wall scratcher A could be firmly secured to the casing string B, but it is preferred to provide for its slidable movement thereon. Thus, the wall scratcher includes a supporting collar or sleeve l0 slidable on a casing section B and adapted to engage stop elements H, i2, such as ring members, welded to the casing section on opposite sides of the scratcher. These stop ele ments I I, !2 may be disposed a few feet apart.

During downward movement of the casing string B in the well bore D, the upper stop element II will engage the collar Ill, forcing the scratcher device downwardly through the Well bore, Slight upward movement of the casing string, such as occurs in lifting it out of the rotary table slips (not shown) at the top of the well bore, will not move the scratcher device A in an upward direction, inasmuch as the lower stop element I2 will not engage the lower end of the collar it during such slight upward movement. Greater upward movement, however, will engage the lower ring I2 with the collar and move the scratcher device A upwardly with the casing string B.

The collar It has an outwardly directed bead portion it formed in it provided with two longitudinally spaced rows It, I5 of :circum'ferentially spaced apertures or holes. The holes of each row are preferably equidistant from each other and the holes in one row I4 are circumierentially ofiset with respect to the holes I5 in another row. Scratcher elements I6 are insertable through the rows of holes, each element being retained in appropriate assembled position on the collar or sleeve Iii, with the finger portions IT, IS of each scratcher element extending outwardly of the collar or sleeve It to a substantial extent.

As seen most clearly in Fig. 8, each scratcher element I5 includes an intermediate, generally U-shaped heel or base portion IS; the spaced arms 26 of which merge into coil portions 2i extending in opposite and outward directions from the base portion i9. Each coil portion 2I consists of a plurality of turns, the outer parts of which merge into the elongate wire fingers El, E3. As disclosed in Fig. 8, each finger includes an inner portion 22 integral with the coil 2!, and an outer portion 23 of substantial length which may be bent transversely in an outward direction with respect to the inner portion 22, to provide a pair of outwardly diverging elongate finger portions [1, I8.

Each scratcher element It is mounted on the cylindrical collar or sleeve Hi from the interior thereof. It is to be noted that the U-shaped heel or base portion #9 of each element It is disposed at an angle to the finger portions I7, 18, as disclosed in Figs. 6 and 7. Each element I6 is inserted through selected holes in the rows I4, is

of apertures formed in the bead I3, the fingers El, if; being extended through adjacent holes in the upper row id of apertures, and the U-shaped heel or base portion I9 being inserted through an aperture in the lower row I5. tions 2! will be received within the confines oi the outwardly directed collar bead portion I3, as shown in Figs. 6 and 7.

The angle that the fingers [7, IS make with the plane in which the heel or base portion i9 iies is such that the fingers I'l', I8 and base portion 59 cannot be mounted through the rows It, iii of apertures unless the fingers and base portion are bent toward each other. Such bending can take place without diificulty, in view of the spring-like characteristics of the coils 2| interconnecting the base portion to the fingers. The fingers Ii, IS and base portion I9 are folded toward each other, and the fingers themselves moved towards a position in which their outer portions 23 are substantially parallel to each other, which enables the fingers of each element to be placed through adjacent apertures in the top row Hi of holes, and the base portion I9 to pass through an intermediate aperture in the The coil porlower row I5 of holes. Thereafter, the folding force imposed on the element It is released, which allows the fingers I'I, I8 to spring back to their initial divergent relationship and the coils 2i to unwind; so as to increase the angle between the plane of the fingers I'I, I8 and the plane of the base portion I9. When the scratcher element It reassumes its initial shape and condition, it cannot move back out through the apertures I4, 55, inasmuch as the depending heel or base portion I9 will engage the collar or sleeve 50 below the loweraperture I5, and the inner portions 22 of the fingers I'I, I8 engage the collar or sleeve above the upper apertures l 4. When the fingers and base portions reassume their initial position, the coils 2| are confined entirely within the bead portion I3 ofthe collar; so as not to project within the inner cylindrical wall of the latter, which might cause interference with the relative slid ing of the casing B within the collar I0.

As disclosed in the drawings, the heel portion l9 of each scratcher element extends downwardly through its own individual lower aperture l5. However, each finger ll of a scratcher element shares an upper aperture It with a finger 58 of the next adjacent scratcher. Thus, as is evident from Fig. 5, one scratcher element I6 is inserted through the adjacent apertures I l and the intermediate aperture I5, and the next adjacent scratcher element is mounted in place in the collar, with its'base portion I9 extending through an adjacent aperture I5 of a lower row. The spring finger I8 at one side of the element extends through the same aperture I l as the spring finger I! of an adjacent scratcher element. Inasmuch as the fingers I'I, I8 of each element diverge from one another, the spring fingers extending through the aperture overlap or cross one another, as is readily apparent from a consideration of Figs. 2 and 5. One finger I! will engage another finger I8 of the next element l6, causing the fingers to mutually support one another. As a'matter of fact, depending upon the extent of divergence of the fingers IT, IS of each scratcher 5 element, one finger I? may overlap several fingers i8 of other scratcher elements, making the construction much stronger.

After the finger elements I7, 58 and base portions I9 are assembled through the apertures I l, I5 within the collar I0, and the fingers and base portions allowed to reassume their initial positions, it is preferred that each spring element be permitted to oscillate to a certain extent about the axis of the coils 2i, before the fingers ll, I8 engage the collar material above the upper row I4 of apertures, or the base portions I5 engage the collar material below the lower row I5 of apertures. This ability of each scratcher element 56 to swing upwardly and downwardly allows the spring fingers II, IS to swing upwardly to a certain extent during downward movement of the scratcher element in the well bore (see full line position in Fig. 6), decreasin the force with which the fingers engage the mud cake or sheath C on the wall of the well bore D, during descent of the apparatus therewithin (Fig. 3).

It is desirable to have very litte, if any, scratching or scraping of the fingers El, IS on the wall of the well bore during lowerin of the casing. However, upon moving the casin upwardly, the spring fingers Il, I8 tend to move from the full line position shown in Fig. '7 to the dotted line position. During such movement, the heel portion I9 is first engaged with the collar material below the lower aperture I 5, which causes the heel, in effect, to serve as an anchor for the coil springs 26. Thereafter, the casing B is elevated and the spring elements It are moved downwardly to the dotted line position shown in Fig. '7, the coil springs 2i being wound or unwound (as the case may be, depending upon the direction in which the coils are wound) to allow the fingers i7, !8 to assume the dotted line position and to also impose a spring force tending to return them to their initial upper position. While the springs are in the dotted line position, they will engage the mud cake or sheath C on the wall of the well bore D with substantial force, scratching and scrapin this mud cake from the wall, allowing circulating fluid pumped down the casing string B to flush the particles of mud cake removed by the scratcher elements It to the top of the hole (Fig. 4).

By reciprocating the casing B through the desired distance in the well bore D the required number of times, substantially all of the mud cake C can be removed from the wall or the hole along the distance traversed by the scratcher A, insuring a proper bond between cementitious material, placed behind the casing, with the formation, and insuring against subsequent channeling through the hardened cementitious material.

As disclosed in the drawings, and particularly Figs. 5 and 9, a large number of turns can be provided in each spring coil portion 2!. As a matter of fact, the coils of the spring elements may be placed closely adjacent one another; so as to substantially completely fill the circumference around the bead [3. There is nothing else disposed in the bead to interfere with the coils, which allows a maximum number of turns to be used, if desired. It is to be understood, however, that the number of turns can be varied, depending upon the spring force required in the fingers I1, is during the scraping operation.

By virtue of the disposition of the spring coils 2! adjacent one another around the interior of the collar bead I3, one coil can abut and support the adjacent coil of another scratcher element, which assists in holding the springs in proper assembled relation within the collar iii. For that matter, it is to be noted that the elements 15 can only move arcuately to a very small extent with respect to the collar l0, since the arms 29 of the U-shaped base member will engage the side walls of the lower apertures l5. In addition, the inner finger portions 22 will also engage the side walls of the upper apertures M, to limit the extent of arcuate movement of each spring element it within the collar or sleeve 50. As stated above, the reassuming of their initial shape by the fingers IT, I8 and base portion 59, after insertion through the apertures l4, l5, precludes the spring elements Hi from moving in wardly of the collar H]. In this connection, any tendency to move inwardly is prevented by the engagement of the periphery of the casing sec tion B with the spring coils 2i The scratcher device A may be made with a single set of springs i 6, or a plurality of sets may be embodied in a single collar or sleeve 56. In the form disclosed in the drawings, the sleeve is of suflicient length to accommodate two circumferential beads 43, and two sets of spring scratcher elements 16 mounted therein. It is preferred to offset the lower set of spring elements it with respect to the upper set; so that a greater circumferential extent of the wall of the well bore D is scratched during reciprocation of the apparatus Within the well bore.

The collar or sleeve [0 may consist of a circumferentially continuous, generally cylindrical member adapted to be slipped longitudinally over the end of the casing section B and into appro priate position, after which the stop elements or rings ll, [2 may be welded, or otherwise suitably secured, to the casing section on opposite sides of the scratcher device. However, the collar or sleeve I 0 may be sectionalized, to facilitate assembly on the casing section by bringing sleeve segments laterally of the casing to a position around the casing section B. As shown in the drawings, the collar may be formed of two sections lila, Illb having hinge knuckles 3c, 3! formed at their confronting end portions, which interleave with one another. Following placing of the sections 10a, lllb about the casing section B, with the spring elements [6, of course, already mounted in each collar section, suitable hinge pins 32, or other fastening elements, may be disposed through the interleaved knuckles 39, 3| on diametrically opposite sides of the scratcher device A, thereby firmly attaching the collar sections Illa, lab to one another, and, in effect. constituting them as a continuous cylindrical member H].

It is, accordingly, apparent that a scratcher device has been provided which is made from a minimum number of parts. In fact, it consists essentially of the collar or supporting member iii and the scratcher elements It themselves, and nothing else. The design lends itself to the automatic formation of the scratcher elements it. and their insertion through theapertures hi, [5 in the collar by automatic equipment, the various elements being properly oriented with respect to each other, resulting in the production of a complete scratcher device A. The lack of any other objects or materials within the collar bead or beads I3 makes it possible to place more spring coils 2| in each element I6, which enhances the flexibility of the spring elements and renders them less susceptible to permanent distortion during reciprocation of the device in the well bore in the performance of the scratching function. A large spring force is available during upward movement of the scratcher to remove the mud cake or sheath 0' from the wall of the well bore; whereas, the spring fingers ll, it can readily fold upwardly against comparatively little resistance, to preclude the imposition of a large scratching force on the mud sheath C during downward movement of the casing string B in the well bore D. In this manner, the mud sheath remains intact during lowering of the apparatus in the well bore, and it is only upon elevation of the casing string to substantial extents, which is done purposely, that the scratching elements it are effective to remove the mud sheath from the well bore wall.

The inventor claims:

1. In a wall scratcher: a supporting member having an outwardly directed bead provided with a plurality of spaced apertures; a plurality of spring elements, each element including a finger extending outwardly through one aperture, a heel portion extending outwardly through another aperture, and a coil spring portion interconnecting said finger and heel portion and dis posed within said bead.

2. In a wall scratcher: a supporting member having an outwardly directed bead provided with a plurality of spaced apertures; a plurality of spring elements; each element including a pair of spaced fingers, each finger extending outwardly through a different aperture, a heel portion extending outwardly through an aperture between the apertures through which said pair of fingers extends, and a coil spring portion within said bead interconnecting said heel portion and each finger.

3. In a wall scratcher: a generally cylindrical collar having a circumferential outwardly directed bead provided with a plurality of longitudinally spaced rows of apertures extending circumferentially around said bead, the apertures or" one row being circumferentially offset with respect to the apertures of another row; a plurality of spring elements having fingers extending outwardly through the apertures of one row and heel portions extending outwardly through the apetures of another row, said heel portions being contactable with the exterior of said collar, each spring element having an intermediate coil spring portion disposed within said bead and interconnecting said finger and heel portion.

4. In a wall scratcher: a generally cylindrical member having a circumferential outwardly directed bead provided with a plurality of upper and lower rows of apertures extending circumferentially around said bead, the apertures of the upper row being-circumferentially offset with respect to the apertures of the lower row, a plurality of spring elements having finger extending outwardly through the apertures of the upper row and heel portions extending outwardly through the apertures of the lower row, said heel portions being contactable with the exterior of said collar, each spring element having an intermediat coil spring portion disposed within said bead and interconnecting said finger and heel portion.

5. In a wall scratoher: a generally cylindrical collar having a circumferential outwardly direct ed bead provided with a plurality of longitudinally spaced rows of apertures extending circumierentially around said bead, the apertures of one row being circumferentially ofiset with re spect to the apertures of another row; a plurality of spring elements; each element including a pair of spaced fingers, each finger extending outwardly through a different aperture of one of said rows, a heel portion extending outwardly through an aperture of another of said rows, said heel portion being oontactable with the exterior of said collar, and an intermediate coil spring portion disposed within said bead and interconnecting heel portion with each of said fingers.

6. In a wall scratcher: a generally cylindrical member having a circumferential outwardly directed bead provided with upper and lower rows of apertures extending circumferentially around said head, the apertures of said upper row being circumferentially offset with respect to the aper-- tures of said lower row; a plurality of spring elements; each element including a pair of spring fingers, each finger extending outwardly through different aperture of said upper row, a heel portion extending outwardly through an aperture of said lower row, and an intermediate coil spring portion disposed within said bead and intercormecting said heel portion with each finger.

'7. In a wall scratcher adapted to be mounted on a running-in string to be disposed in a well bore: a supporting member having a plurality of spaced apertures; a plurality of spring elements, each element including a finger extending outwardly through an aperture, a heel portion extending outwardly through another aperture and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said member, and an intermediate portion interconnecting said finger and heel portion and disposed within said member; said supporting member having a portion abutting said intermediate portion to prevent bodily movement of said spring element along said supporting member.

8. In a wall scratcher adapted to be mounted on a running-in string to be disposed in a well bore: a supporting member having a plurality of spaced apertures; a plurality of spring elements, each element including a finger extending outwardly through an aperture, 2. heel portion extending outwardly through another aperture and alongside said member and contactable with said member, whereby said heel portion will substantialiy overlap the exterior surface of said member, and a coil spring portion interconnecting said finger and heel portion and disposed within said member; said supporting member having a portion abutting and embracing said coil spring portion to prevent bodily movement of said spring element along said supporting member.

9. In a wall scratcher adapted to be disposed in a well bore: a supporting member having a plurality of longitudinally spaced rows of apertures, the apertures of one row being offset with respect to the apertures of another row; a plurality of spring elements, each element including a finger extending outwardly through aperture of one row, a heel portion extending outwardly through an aperture of another row and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said memher, and an intermediate portion interconnecting said finger and heel portion and disposed within said member; said supporting member having a portion abutting said intermediate portion to prevent bodily movement of said spring element along said supporting member.

10. In a wall scratcher adapted to be mounted on a running-in string to be disposed in a well bore: a supporting member having a plurality of spaced apertures; a plurality of spring elements, each element including a pair of spaced. fingers, each finger extending through a different aperture, a heel portion extending outwardly through an aperture between the apertures through which said pair of fingers extend and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said memher, and intermediate portions interconnecting said fingers and heel portion and disposed within said member; said supporting member having a portion abutting said intermediate portions to prevent bodily movement of said spring element along said supporting member.

11. In a wall scratcher adapted to be mounted on a running-in string to be disposed in a well bore: a supporting member having a plurality of spaced apertures; a plurality of spring elements, each element including a pair of spaced fingers, each finger extending through a different aperture, a heel portion extending outwardly through an aperture between the apertures through which said pair 'of fingers extend and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said member, and coil spring portions interconnecting said fingers and heel portion and disposed within said member; said supporting member having a portion abutting and embracing said coil spring portions to prevent bodily movement of said spring element along said supporting member.

12. In a wall scratcher adapted to be disposed in a well bore: a supporting member having a plurality of longitudinally spaced rows of apertures, the apertures of one row being ofiset with respect to the apertures of another row; a plurality of spring elements, each element including a pair of spaced fingers, each finger extending through a diflerent aperture of one row, a heel portion extending outwardly through an aperture of another row and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said member, and intermediate portions interconnecting said fingers and heel portion and disposed within said member, said supporting member having a portion abutting said intermediate portions to prevent bodily movement of said spring element along said supporting member.

13. In a wall scratcher adapted to be disposed in a well bore: a supporting member having a plurality of longitudinally spaced rows of apertures, the apertures of one row being offset with respect to the apertures of another row; a plurality of spring elements, each element including a pair of spaced fingers, each finger extending through a different aperture of one row, a heel portion extending outwardly through an aperture of another row and alongside said member and contactable with said member, whereby said heel portion will substantially overlap the exterior surface of said member, and coil spring portions interconnecting said fingers and heel portion and disposed within said member; said supporting member having a portion abutting and embracing said coil spring portions to prevent bodily movement of said spring element along said supporting member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 665,226 Johnston Jan. 1, 1901 1,358,481 Traphagen Nov. 9, 1920 1,820,391 Hartman Aug. 25, 1931 2,150,435 Floreth Mar. 14, 1939 2,364,303 Martin Dec. 5, 1944 2,412,876 Edwards Dec. 17, 1946 2,421,434 Reistle et al. June 3, 1947 2,427,632 Stephens Sept. 16, 1947 2,506,405 Wright May 2, 1950

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