US2845129A - Casing scraper - Google Patents

Description

July 29, 195s 1R. BAKERv 2,845,129

' cAsING SCRAPER v Filed Sept. 26, 1.955A 2 Sheets-Sheet 1 chf@- July 29,1958 J, R, BAKER 2,845,129

CASING scRAPER Filed Sept. 26. 1955 2 Sheets-Sheet 2 INV-ENTOR. 9

United States Patent() CASING SCRAPER .lohn R. Baker, Pasadena, Calif., assigner to vBaker Oil Tools, Inc., Los Angeles, Calif., acorporation ot'Calrn fornia Application September 26, 1955Seral No. 536,406

lil Claims. (Cl. 166-173) The present invention relates to scraping devices, and more particularly to Scrapers especially useful in theremoving of undesired substances or protuberances from the inner wall surfaces of well casing, liners, and similar conduits disposed in well bores. y

An object of the present invention is lto provide a device for scraping the walls of well conduits, that has a much stronger body on which the scraper yblades are mounted, and in which the blades can also be made much stronger without increasing the over-all size of the device.

Another object of the invention is to provide a casing scraper having spring devices for urging the scraper 'blades outwardly against the casing wall, the scraperpossessing fewer parts, being of simpler construction, and easier to assemble and disassemble.

A further object of the invention is to provide a casing scraper embodying improved spring devices .for urging expansible scraper blades outwardly against the casing wall, the spring device exerting its force along substantially the entire length of the blade on opposite sides thereof, thereby rendering the scraperblade more stable in its operation upon the casing wall.

The invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part .of `the present specification. These yforms will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is sto be understood that such detailed description is not v.to .be taken in a-limitingsense, since the scope of the invention is best dened'by the appended claims.

Referring to the drawings:

Figure l is a side relevation .of a'casing scraper disposed in a well casing, parts of the tool beingshown in section;

Fig. 2 is an enlarged partial longitudinal section taken along the line 2-2 on Fig. l;

Fig. 3 is a crossfsection taken generally along' the line 3-,3 jon Fig. 2; A

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

Fig. '5 is a cross-section.taken along the line 5--5 on Fig. 2;

Fig. 6 is a fragmentary sideY elevation of a spring deviceass'embled in y'the 'body of the tool;

Fig. 7 is an visometric projection ofone of the spring elements forexp'anding a scraper 'blade outwardly;

Fig. 8 is a cross-sectionthrougha modied form ,of the invention. i

The casing scraper A shown Vin the drawings is adapted to operate upon the inner wall of a Ywell casing, liner or similar conduit B-dispo'sed Vin the well bore and through which it is movable. AThe main fbody 10 of the scraper is `a' generally elongate tubular'fmeniber provided with a central iluid passage J11. A threaded pin is formed at the upper end of the body Afor:threaded'.attachment rice to the lower end of a string of drill ,pipe C running to the top of the well bore, through .the use of ,whichthe tool is moved in the well casing B both longitudinally and rotationally. The lower end lof the body Vmay V.be formed as a threaded box 13 ladapted to be threadedly attached to the upper pin 14 of the main body of the lower drill bit D. This latter tool -D need not be used unless it is desired to drill out a substantial obstruction extending transversely across the casing bore. Circulating fluid may be pumped down the drill pipe C yandentirely through the fluid passage 11 in the ymain scraper body lil, vilowing down through the vlower bit ,passage 15, from which it exits into the annulus E between the casing B and the apparatus A, C, D .disposedthereim This circulating liuid ows upwardly through isuch annulus to flush the cuttings to the top ofthe wellbore.

The casing scraper has a .plurality of sets 16, 17 of scraper blades 18 and cooperating elements that are angularly displaced with respect ,to each other, the cutting surfaces or edges 19 of the blades collectively 0perating upon the entire circumference of the well casing. As specifically shown in the drawings, two sets of scraper blades 18 and associated elements are disclosed, one set being displaced about 60 degrees with respect to Athe other set. lSince each set 'is shown as including three scraper blades, andV since each blade has an effective arcuate extent of about 70 degrees, it-is apparent that each set of blades will scrape a total of 210 degrees of arc around the circumference kof the casing B, and both sets will scrape about 420 degrees of arc around the casing. Accordingly, the blades 18 of kone set 16 lactually overlap the blades 18 of the other set 17 insofar .as scraping action is concerned, `giving'full assurance ,that

the Ventiresurface of the casing wall will be covered upon longitudinal movement of the tool A (non-rotary .movement) in the Awell casing'B.

Since both sets of Scrapers ,and associated elements fare alike, although angularly displaced, a `detailed description of one set will suflice for both.

In connection with the'upperset 16 of'blades '18,'1the main generally cylindrical scraper body Y1t) 'is' provided with a circumferential groove 20 of substantial :elongate extent. The scraper blades 18 are disposed'within :this groove 20 and are Vpreferably equi-angularly displaced from one another. Each blade is provided with axially separated -helical scraper teeth 19 :inclined tolthe :axis of the tool lto a substantial extent. The lowerfsurfaces 19avofV these teeth maybe suitably hardfaced to'enhance their useful life. 'The 'inner ,portion `of each Ablade 18 is provided with oppositelyand outwardly extending elongate curved wings 21 which provide Vstopsr Aor'shotilders 22. These stops or shoulders are.cooperablewithcmpanion overlapping wings 23 'extending outwardlyin opposite directions from the main central body portions `24 of Van elongate -blade retainer or stopfmember .25.

lThese stopfmembers ZSareequiangularly displaced from one another within'the body grooves 2.0 land'fareidisposed between the blades 18, alternating therewith, as clearly shownin Figs. 3, 4'and 5.

The inner -wings 21 onthe yblades will rengage the .outer wings l23 on the blade retainer 'memberrZS iso''that routward lateralexpansion fof the blades 1-8is limited. fEach retainer member 25 'has one `wing cooperating'withthe shoulder 22 on -one blade, the opposite wing v'255 :of'the same 'retainer member being cooperable 'with the shoulder 22 on the next succeeding blade Iaround ithe" circumference of the tool.

The segments 'or stopmembers /25 :are rfirmly:#secured to the main body 10 of the'tooltoforin a 'rigid abmtrn'ent for vthe blades 18. As `disc'losecLzeach'segmentihasflipper `and lower end ears 26from'which upper'and ilowe'rahlgs 27 4extend in an inward direction. Anvintermedia'tezlug 28 also extends inwardly from the main body 24 of the retainer, although such intermediate lug may be omitted, if desired. The ears 26 and lugs 27 are provided with holes 29, each of which has an outer counterbore 30, these holes being in alignment with threaded holes 31 formed in the main scraper body 10. Fastening elements 32, such as screws, are inserted through the holes 29 for threaded reception in the body bores 31, the heads 33 of the screws being received within the counterbores 30.

The circumferential grooves 2t) formed in the body 10 can be turned readily in a lathe, so that the base 34 of each groove is cylindrical in shape. At the upper and lower sides 35 of the circumferential groove 20, and in the same radial central planes as the blades 18 and retainer members 25, the body is provided with recesses 36, 37 that may be formed with a milling cutter. The end ears 26 of each blade retainer segment extend into an upper recess 36 and a lower recess 36, the upper and lower lugs 27 fitting snugly against the at bases 38 of these recesses so that there is flat bearing engagement between the parts.

Each blade 18 is urged outwardly of the scraper body by a flexible member in the form of a leaf spring 40. The springs 40 bear against the scraper body 10 and against the scraper blades 18 in a particular manner, as described in detail hereinbelow, urging the blades outwardly to the extent limited by engagement of the blade wings 21 with the overlapping or overhanging wings 23 of the retainer segment 25. To avoid interference between each scraper blade 18 and the intermediate lugs 28 on the retainer member, during the inward or outward movement of the blade, the wings 21 on the blades may vbe provided with notches 43 of sufficient extent as to clear ythe scraping elements or teeth 19 on the blades collectively cover the entire circumference of the casing wall, the casing B can be scraped effectively merely by moving the tool longitudinally in the well casing. The springs 40 urge the blades 18 outwardly with substantial force against the wall of the casing B, assuring removal of any undesired substances from the well casing.

The blades 18 preferably make a sliding fit with the end walls 35 of the groove 20, so that any longitudinal thrust is transmitted directly between the scraper body 10 and the blades 18. In the event the tool is rotated to accomplish the scraping action of the casing wall, the blade retainer members will drive the blades in a rotary direction. However, it is preferred to furnish another driving arrangement, which also serves to guide each blade 18 in its lateral movement inwardly and out- -wardly of the casing body 10.

-tted within the recesses 37 and are secured to the body 10 as by use of welding material 48. The-upper and lower driving blocks 46, 47 for each blade extend toward each other and tit within the end notches 44, 45 in the blade 18. The fit is preferably a sliding one with the -walls of the notches 44, 45 so as to guide each blade in its movement inwardly and outwardly of the main body 10. The outer portions 49 of each driving member 46, 47 are preferably flush with the periphery of the body 10, whereas the inner portions 50 may be enlarged transversely, furnishing a greater surface of contact between such large portions 50 and the wall of the notches 44, 45.

condition disclosed in Fig. 7.

Should it be desired to remove material from the casing wall by a rotary operation, the drill pipe C and main body 10 are rotated, this movement being transmitted directly to the blades 18 through the driving blocks and members 46, 47. The inclination of the blade teeth 19 insures full coverage of the inner surface of the casing wall B.

The spring 40 for urging each blade outwardly is at when unconfined, being of a leaf type (see Fig. 7). This spring is disposed in a body groove 20 behind each blade 18, being of a width that is greater than the width of a blade and of a length that is substantially the same as the length of each blade. The center line portion 70 of each spring 40 will engage the base 34 of the circumferential groove, whereas the side or marginal portions 71 of each spring will engage the wings 21 of each blade along substantially their entire length.

To prevent the driving members 46, 47 from interfering with the ability of each spring 40 to ex, each spring is provided with upper and lower notches 72 that freely receive the upper and lower driving blocks 46, 47. ln addition, each springlis provided with side notches 73 into which the intermediate lugs 28 of the blade retainers 25 can extend, so that such intermediate lugs also are prevented from interfering with the deflection of the leaf spring in being forced inwardly toward the base 34 of the groove by the load on the blade, or in tending to straighten out, or expand outwardly, so as to correspondingly shift the blade 18 laterally outward of the body 10 of the casing scraper. The upper and lower driving blocks 46, 47, as well as the intermediate lugs 2S, tend to retain each spring 40 in its appropriate position within the groove 20 and behind its associated blade 18, insuring its proper action upon the blade and upon the base 34 of the circumferentially continuous groove 20.

When unconlned, each leaf spring 40 is in the at In assembling the apparatus, each spring is inserted in the circumferential groove 20, with its upper and lower notches 72 appropriately disposed over the upper and lower driving blocks 46, 47. Bach blade is then placed in appropriate position, with the upper and lower blade notches 44, 45 receiving the upper and lower driving blocks, the blade then being depressed by means of a suitable tool down- Vwardly against the force of the leaf spring 40. The central portion 70 of the spring will engage the base 34 of Ythe groove, the wings 21 of each blade engaging the side margins 71 of the spring and bending or deflecting the latter into an outwardly convex form, such as disclosed in Figs. 3, 4 and 5. The blade retainers 25 are then mounted between the blade members 18 and are appropriately fixed to the body 10 by the upper and lower screws 32. The intermediate lugs 28 in the blade retainers will pass through the side notches 73 in the springs 40, to avoid interference with the ability of the spring margins 71 to move inwardly and outwardly. Once the screws 32 have all been tightened, the tool (not shown) that has been restraining the blades can be removed and each leaf spring 40 will then tend to straighten out, the side margins 71 urging the blades 18 outwardly to the extent determined by engagement of the side wings 21 with the retainer wings 23.

When the tool A is inserted in the well casing B, since the inside diameter of the casing is usually somewhat less than the unrestrained diameter across the blades 18 with the tool out of the hole, the engagement between the blades and the inner wall of the casing will move the blades inwardly to a slight extent against the force exerted by the springs 40. That is to say, the blade wings 21 will move inwardly out of contact with the retainer wings 23. During the downward movement of the apparatus in the well casing, the blade teeth 19 will collectively scrape the entire circumference of the casing.

`Iff at any time it is desired to eiect a scraping action by rotating the drill pipe C and the scraper A itself, the inclination of the helical teeth 19 will insure the performance of the appropriatey scraping action during rotation of the blades around and along the inner wall of the casing. During the entire operation of the tool, whether it is moved merely longitudinally or rotationally only, or with a combination of such movements, the springs 40 will be constantly urging the blades 18 outwardly, to insure the exertion of an adequate scraping force of the blade teeth 19 against the wall ofthe well casing.

By virtue of the use of the leaf springs 40 behind each casing, it is possible to make each blade 18 much thicker than heretofore without increasing the over-al1 diameter of the tool measured to the edges of the scraper teeth 19. Thus, each blade will be much stronger. In addition, the leaf springs 40 make it possible to maintain the diameter of the base 34 of the circumferentially continuous groove, the base of this groove being uninterrupted so as to insure that it possessesa full annular cross-section, such as disclosed in Figs. 3, "4 and 5. The base 34 of the groove can b'e made without anyinterruptions in its surface, such as radial holes and the like (not shown), which would reduce the cross-sectional area in the region of such holes and which would also provide points at which fatigue failures could occur. Actual experience has shown that absence of any holes or depressions in the base 34 of the grooves 20 greatly increases the strength of the body 10 and guards against the body twisting otf, or otherwise failing in the region ofthe grooves 20. Where holes 31 are provided in the body, as for the screws 32, Vthe cross-sectional area of the body is much greater, since such holes are disposed Ylongitudinally to one side of the circumferentiallyvcontinuous groove Zt).

It is to be noted that the side margins 71 of the leaf springs are always tending to move out because of the spring characteristics of the spring elements, and that such margins engage the wings 21 along substantially their entire length. Thus, the spring force is exerted in an outward direction along two widely spaced lines of contact with each blade, urging the blade outwardly without any tendency `for its tilting within the circumferential groove 20. The blade 18 moves inwardly and outwardly to substantially the same extent along its entire length. The use of the single spring 40 also minimizes the radial space that is required between the inner surface of the blade and the base 34 of the groove, permittingblades of much greater radial thickness to be employed. In addition, Vassembly of the tool is much simpler than in devices heretofore used, which normally included a plurality of radial helical compression springs disposed at separated points longitudinally along each blade.

The inventor claims:

1. In a casing scraper: `a main 'body attachable to a drill string and having a groove therein; a scraper blade in said groove shiftable laterally therein and adapted to extend outwardly of said body, said blade having side margins; and at least one leaf spring in said groove substantially coextensive in length with said blade, said spring having a central portion engaging the base of said groove and side margins engaging the side margins of said blade, said central portion being free from engagement with said blade and said side margins of said spring being free from engagement with said base of said groove, whereby said blade is urged outwardly of said body; and means for limiting lateral outward movement of said blade in said groove.

2. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein around its entire circumference, said groove having a base of substantially circular cross-section; circumferentially spaced scraper blades in said groove shiftable laterally therein and adapted to extend outwardly of said body, each of said blades having side margins; leaf springs in said groove behind said blades substantially coextensive in length therewith, each spring having a central portion engaging said baseand 'side lmargins engaging the side margins of a blade, said central portion being free from engagement with said blade and said side margins of each springbeing free from engagement with said base of said groove, whereby each blade Yis urged outwardly of said body; and means for limiting lateral outward movement of said blades in said groove.

3. In a casing scraper: a main body attachableto a drill string, said body having an external groove therein around its entire circumference, said groove having a base of substantially circular crossesection; circumferentially Vspaced scraper blades in said groove shiftable laterally therein and adapted to extend outwardly of said body,

each of said blades having side'margins; Vmeans providing a slidable connection between said body and each of said blades; leaf springs in said groove behind said blades substantially co-extensive in length therewith and slidable along said slidable connections; said springs having central portions engaging said base and side margins engaging the side margins of said blades, said central portions being free from engagement with said blades and said side margins being free from engagement with said base of said groove, whereby said blades are urged outwardly of said body; and means for limiting lateral outward movement of saidr blades in said groove.

4.In a casing scraper: a main body attachable to a drill string, said'body having an external groove therein around its entire circumference; circumferentially spaced scraper `blades in said groove `shiftable laterally therein and 'adapted to extend outwardly of said body, each blade having scraping portions and also side wings extending outwardly iny opposite vdirections beyond the scraping portions; a leaf spring behind each blade substantially coextensive in length with said blade, said spring having its central portion engagingthe base of said groove and its side margins engaging said wings, said central portion being free from 'engagement with said blade and said side margins of said spring being free from engagement with said base 'of lsaidgroove, whereby said blade is urged outwardly of 'said body; and blade retainer members in said groove between said blades, each of said retainer members overlapping the side wings of the blades on opposite sides of the retainer vmember for limiting the outward movement of said blades.

5. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein around its entire circumference; 'circumferentially spaced scraper blades in said groove shiftable laterally therein and adapted to extend outwardly of said body, each blade having scraping portions and also side wings extending outwardly 'in kopposite directions beyond the scraping portion`s;fat least 'one leaf springbehind each blade, said spring havinga central portion engaging the base of said groove and side margins engaging said wings, said central portion being free from engagement with said blade and said side margins of said spring being free from engagement with said base of said groove, whereby said blade is urged outwardly of said body; and blade retainer members in said groove between said blades, each of said retainer members overlapping the side wings of the blades on opposite sides of the retainer member for limiting the outward movement of said blades; each spring having notches in its side margins receiving said retainer members.

6. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein; a scraper blade in said groove shiftable laterally therein and adapted to extend outwardly of said body; said blade having an end groove; a driving member secured to said y body and slidably received in said end groove to guide said blade for movement laterally of said body; and a leaf spring in said groove having a rst portion engageable with said blade and a second portion engageable with the base of said groove, said second portion being free from engagement with said blade and said rst portion being free from engagement with said base of said groove, whereby said blade is urged outwardly of said body, said spring having an end notch receiving said driving member; and means for limiting outward movement of said blade in said external groove.

7. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein; a scraper blade in said groove slidable laterally therein and adapted to extend outwardly of said body, said blade having upper and lower substantially central end grooves therein extending inwardly toward each other from the upper and lower ends of said blade; driving members secured to said body and slidably received in said end grooves to guide said blade for movement laterally of said body; and a leaf spring in said groove having a first portion engageable with said blade and a second portion engageable with the base of said groove, said second portion being free from engagement with said blade and said first portion being free from engagement with said base of said groove, whereby said blade is urged outwardly of said body, said spring having upper and lower end notches receiving said driving members; and means for limiting lateral outward movement of said blade in said external groove.

8. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein; a scraper blade in said groove shiftable laterally therein and adapted to extend outwardly of said body, said blade having side margins and upper and lower substantially central end grooves therein extending inwardly toward each other from theupper and lower ends of said blade; driving members secured to said body and slidably received in said end grooves to guide said blade for movement laterally of said body; and a leaf spring in said groove having a central portion engaging the base of said body groove and its side margins engaging the side margins of said blade, said central portion being free from engagement with said blade and said side margins of said spring being free from engagement with said base of said groove, whereby said blade is urged outwardly of said body, said spring having upper and lower end notches receiving said driving members; and means for limiting lateral outward movement of said blade in said external groove.

9. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein around its entire circumference; circumferentially spaced scraper blades in said groove shiftable laterally therein and adapted to extend outwardly of said body, each blade having scraping portions and also side wings therein extending outwardly in opposite directions beyond the scraping portions; each blade having upper and lower substantially central end grooves therein extending inwardly toward each other from the upper and lower ends of said blades; driving members secured to said body and slidably received in said end grooves to guide said blades for movement laterally of said body; leaf springs in said body groove behind said blades, each spring having a central portion engaging the base of said body groove and side margins engaging said wings, said central portion being free from engagement with said blade and said side margins of each spring being free from engagement with said base of said groove, whereby each blade is urged outwardly of said body; each of said springs having upper and lower end notches receiving said driving members; and blade retainer members in said groove between said blades, said retainer members overlapping the side wings of the blades on opposite sides of the retainer member for limiting the outward movement of said blades.

10. In a casing scraper: a main body attachable to a drill string, said body having an external groove therein around its entire circumference; circumferentially spaced scraper blades in said groove shiftable laterally therein and adapted to extend outwardly of said body, each blade having scraping portions and also side wings therein extending outwardly in opposite directions beyond the scraping portions; each blade having upper and lower substantially central end grooves therein extending inwardly toward each other from the upper and lower ends of said blades; driving members secured to said body and slidably received in said endy grooves to guide said blades for movement laterally of said body; leaf springs in said body groove behind said blades, each spring having a central portion engaging the base of said body groove and having side margins engaging said wings, said central portion being free from engagement with said blade and said side margins of each spring being free from engagement with said base of said groove, whereby each blade isurged outwardly of said body; each of said springs having upper and lower end notches receiving said driving members; blade retainer members in said groove between said blades, said retainer members overlapping the side wings of the blades on opposite sides of each retainer member for limiting outward movement of said blades; each spring having notches in its side margins receiving said retainer members.

References Cited in the Iile of this patent UNITED STATES PATENTS 1,355,726 Zlatnik Oct. 12, 1920 1,443,474 Inskeep Jan. 30, 1923 2,667,931 Baker Feb. 2, 1954 2,695,673 Coyle Nov. 30, 1954

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