US2275939A - Casing scraper - Google Patents

Description

R. @BAKER GASING SCRAPER Filed March 4, .1941

March 10, w42.

INVENTOR.- AKEA?,

ATTORNEY Patented Mar. 10, 1942 CASING SCRAPEB Reuben C. Baker, Coalinga, Caiif.assiznor to Baker Oil Tools, Inc., Vernon,

ration of California Calif., a corpo- Appucation March i4, 1941, serial No. 381,660

' (or 16s- 18) 8 Claims.

This invention relates to devices for cleaning the inner walls of well casings or liners, and is more particularly concerned with a rotatable casing scraper capable o scraping a lm of cement, paraiiin or any type of scaly material from the inner wall of such casing string or liner.

In cementing a well casing or liner in a well bore, it is necessary to drill out the hardened cement or tailings left in the lower portion or the cemented casing string. Due to the, running clearance that must be allowed, the drill bit employed for removing this hardened material leaves a nlm or sheath of cement as a coating on the inner wall of the casing. This illm oftentimes prevents the proper setting of packers within the casing, and also tends to iiake oil and clog testing, production and other apparatus employed in the well bore.

It is, therefore, an object of the present inventlon to provide a casing scraping device designed to emcie'ntly remove the cement or other coating from the inner wall of a string of casing. The' present invention is also concerned with a comparatively simple and sturdy casing scraper construction in which the scraper blades are yieldably mounted so as to automatically adjust themselves to the surface oi' the casing and be maintained always in pro'per scraping engagement therewith. These blades arevheld on the scraping tool body in such a manner as to facilitate their assembly land disassembly, making it necessary only to replace worn blades after each run of the tool.

A further object of the invention is to provide a scraper embodying yieldable, automatically ad- :f

justable elongate blades designed to scrape the wall oi a casing. The scraper can be incorporated in a drilling string as a component part thereof, and is capable of conveying drilling fluid from the drill string to a bit positioned below the casing scraper.'

The invention has other objects that will become apparent from a consideration of the embodiments shown in the drawing accompanying and forming part of the present specification. These forms will now be described in detail, but it is to be understood that such detailed description is not to be taken in a limited sense, since the scope of the invention is best defined by the claims appended hereto.

Referring to the drawing:

Figure 1 is a side elevation of a casing scraper, parts being shown in section; l

Figure 2 is an enlarged transverse section, taken as indicated by line 2 2 in Figure 1;

Figure 3 is a view similar to Figure 2 of an otherform ofthe invention; and

Figure 4 is a section through a well casing and bore hole showing the casing scraper in use.

Each of the casing scrapers A disclosed in the drawing includes an elongate body le provided with suitable upper and lower connections for v incorporating the tool in a suitable string oi drill pipe or tubing. As specifically illustrated, the upper threaded pin il serves to couple the body to an adjoining drill collar or joint oi pipe B. while the lower threaded boxv lmay be usedto attach a drill bit C to the scraper body. A passageway i3 extends centrally through' the body for conveying drilling iiuid from the drilling string B to the attached drill bit C, or, if no bit is used,- for discharge from the lower end of the body into the well casing D or bore hole.

Circumferentially spaced longitudinal grooves ld are provided in the exterior of the scraper body or shank ld for receiving longitudinal scraper blades or cutters l5 designed to havea radially free sliding t in connection with the side walls l, ita and end walls il', il of the body grooves. Each or these blades iii has a longitudinal cutting or scraping edge le adapted to cooperate with the wall of the casing D for operation upon any adherent scaly or cementitious material. Coilsprings la are contained within inner sockets or pockets 2@ formed in each blade `with their inner ends engaging the bottom 2i of the groove ld, so as to force the cutting edge i8 of the blade outwardly against the wall of the casing, which outward movement is limited by the retainer members d2, 23 engageable with the reduced upper and lower terminals 2d, 2t of the blade.

In the present instance, 'outward movement oi the upper portions 2d of the blades under the iniiuence of the helical springs i9 is limited by a i retainer collar 23 seated within a lrecess 2b in the exterior oi the tool shank or body l, and welded thereto preferably iiush withthe external surface of the body. This collar extends over the upper ends of the grooves l and is engageable with the upper blade terminals 2d. The lower re.

tainer 22 consists of removable arcuate segments 26 received within a circumferential body groove 2l and secured to the main body ofthe tool by s crews 28, whose heads are suitably recessed within the segments. Each segment 25 has an upstanding skirt 29 overlying the lower ends of the grooves i@ and capable of engagement with the lower blade terminals 24 to limit vthe'extent o f their outward movement. f

Due to the arrangements of parts justv described, the blades I5 may readily be assembled on and dismantledfrom the body I of the transversely both inwardly and outwardly for Y the purpose of maintainingthe scraper edges I8 scraper tool. Each blade is inserted in its asso,- A

ciated groove I4 with the required number of springs I9 within its sockets 20. The upper terminal 2'4 of each blade-is placed under the upper collar 23,-and the blade depressed far enough 'within the groove against the force of the springs until its lower reduced terminal 24 is positioned far enough within the groove to permit one of the retainer segments 26 to be placed over this -terminal and secured to the body by the screws 28, which are fully tightened to complete the assembly of the blade in the tool body. The other blades I are mounted in the same manner.

In the fully assembled scraper tool, the retaining members 22, 23 not only limit outward movej ment of the blades I5 under the action of the springs I9, but prevent their inadvertent removal from the tool body I0. After the blades have become worn and their replacement is de sired, the lower retainer segments 26 need only be removed, which will permit withdrawal oi the blades, and the insertion of another set in their place.

The assembled tool A may be placed at any desired or required point in the string of drill pipe or tubing. An example of its use is shown in the drawing, in which the scraper is disposed between the drill collar B and any suitable form of rotary drill bit. C, with its upper threaded pin II screwed into the drill collar and its lower threaded box I2 receiving the usual pin at the upper end of the bit.

until the top of the hardened cement E within the casing is reached. Rotation of the drilling' string at the proper speed and with the proper weight imposed upon the drill bit C is then undertaken to disintegrate the cement in the casing and effect its flushing or removal to the surface of the well bore. Y y

Because of the running clearance necessary between the drill bit C and the wall of the casing, the former is incapable of removing all of the hardened cement, leaving a thin film coating the inner wall of the casing. This film or sheath is effectively removed by the casing scraper A, whose blades I5 are forced outwardly into intimate contact with the casing along substantially their whole length by the coil springs I9.

It is to be noted that the ends 30 of the scraper blades are inclined inwardly to the scraper airis` so as to insure riding of the blades over the ends ofthe casing sections at the casing couplings. and prevent the tool from hanging up inside the casing. The lower tapered ends 30 facilitate en- .try of the tool in the casing and also operate upon the cement sheath to assist its, removal. If any restrictions are encountered while running in the casing, their engagement by thesetapered ends 30 forces the blades I5 inwardly against the actions of the coil springs I9, permitting the tool to move past the obstruction. If the ob struction is drillable, rotation of the tool will effect its removal from the casing in the same manner as the cement sheath' is removed.

The tool A is so designed and proportioned that the terminals 24 of the blades are spaced inwardly from their collar 23 and retainersegments 26 when being operated'in the casing, the

casing wall forcing the .blades inwardly against the actionof 4the springs I9.. l As a result, each Y madeiscapable-oi moving. generally radially or always in contact with the casing. The blades are self-adjusting to conform to the diameter of the casing at all times, the springs' I9 serving to equalize the bearing action ofv the blades upon the walls of the casing. and causing them to take their proper share-of the load.

The movement of the blades I5 in their conning grooves I4 is facilitated by providing bleeder or breather holes 3| through the blades between their interiors'and exteriors, permitting fluid to by-pass to and from each groove I I as the blade moves inwardly and outwardly. In place of the holes 3|, a notch 32 may b e provided in the leading side face I6 of each groove,- extending downwardly to the bottom 2l of the groove, through which fluid can pass readily between the .region below the blade and the exterior of the tool body III. If desired, for a better bleeding of the fluid, both the holes 3| and notch 32 are employable, although one expedient may be used in preference to the other.

By use of the tool A in combination with the drilling blt C, assurance is had that all of the cement is removed from the casing. The` drill bit and scraper cuttings are flushed from the casing by the usual stream of drilling fluid passing downwardly through the drill pipe B, scraper body I0, and drill bit C for action upon the bit blades, and for upward passage past the casing scraper blades I5, lcarrying all cuttings with it to the surface of the bore and maintaining th scraper blades substantially clean. l i

For the most eiective and efficient angle of attack on the wall of the casing, the scraping or cutting edges lI8 ,of each blade should lie in a radial plane extending from the centerline or axis of the body I0. To obtain this arrangement, each blade groove I4 can be disposed generally symmetrically of the radial plane (as shown in Figure 3), with the blade having a recess 33 to provide a cutting edge I8 lying in such plane; or each groove I4 can be disposed t0 one side of the radial plane, with its leading side I5 coinciding therewith to place the leading face 34 of the blade and its hardfaced longitudinal cutting edge ls in th same raam position. This latter design is preferred since it lprovides a stronger cutting. blade. In both embodiments, the blades I5 are bevelled toward their trailing side 35 to limit their contact with the casing o; cement sheath to the leading cutting edges I By use'of the invent-ion just described, no ce- I mentitious or other foreign matter is left adhering to the wall of the casing, removing a barrier and hazard to the successful operation of other well tools in the casing. Formation testers, perforationwashers, packers, etc. can be set against the metal of the casing itself, and flow beans or other production equipment cannot be plugged or restricted by cement particles flaking and for maintaining their longitudinal scraping edges yieldably in engagement with the wall of well casing during operation of said casing scraper therewithin, and stop means engageable with said blades for limiting the extent of their l scraping edges maintained generally parallel to said body axis and yieldably in engagement with the wall of a well casing during operation of said casing scraper therewithin, and stop means engageable with said blades for limiting the extent of their outward movement.

3. A rotary casing scraper; including a body adapted for attachment to a drilling string and having a iiuid passage therethrough; said body having a plurality oi circumferentially spaced longitudinal grooves in its exterior whose bottoms are parallel to the body axis; a cutter blade I slidably mounted in each groove; said blade having an outer longitudinal scraping edge parallel to said body axis, a plurality of inner sockets and reduced terminal portions; coil springs engaging the bottoms of said grooves and received within said sockets for moving said blades bodily outwardly withtheir longitudinal scraping edges maintained generally parallel to said body axis and yieldably in engagement with the wall oi a well casing during operation of said casing scraper therewithin; respective retainers secured to said body and overlying the ends of said grooves toengage said reduced terminal portions and limit the extent o i outward movement of each blade, one of said retainers being readily removable to permit assembly and disassembly of said blades on said body.

4. A rotary casing scraper: including a body having a longitudinal fluid passage therethrough and upper and lower threaded joints for attaching said body to a drilling string; said body having a plurality of circumferentially spaced longitudlnal grooves in its exterior whose bottoms are -parallel to the body axis; a cutter blade slidably mounted in each groove; said blade having an outer longitudinal scraping -edge parallel to said body axis, a plurality oiv inner sockets and reduced terminal portions; coil springs engaging the bottoms of said grooves and received within said sockets for moving said blades bodily outwardly with their longitudinal scraping edges maintained generally parallel to said body axis and yieldably in engagement with the wall ot a oi such outward movement.

well casing during operation of 4said casing scraper therewithin; respective retainers secured to said body and overlyingthe ends of said grooves to engage said reduced yterminal portions and limit the extent of outward movement of each blade, one of said retainers comprising a collar allel to the body axis and lying in a radial plane extending from the body axis, spring means in each groove for moving each blade bodily outwardly with its scraping edge maintained in said plane generally parallel to said axis and yieldably in engagement with the wall of a well casing during operation of said scraper therewithin, yand stop means for limiting the extent of such outward movement. i

6. A rotary casing scraper, including a body adapted for Vattachment to a drilling string, said body having a plurality of circumferentially spaced longitudinal grooves in its exterior, a cutter blade slidably mounted in each groove land having an-outer longitudinal scraping edge parallel to the body axis, the leading faces of each groove and saidscraping edge lying in a radial plane extending from said axis, spring means in suchgroove for moving each blade bodily outwardly with its scraping edge maintained in said plane generally parallel to said axis and yieldably in engagement with the wall of a well casing during operation of said casing scrapertherewithin, and stop means for limiting the extent '7. A rotary casing scraper, including a body adapted for attachment to a drilling string, said vbody having a plurality of circumferentially spaced longitudinal. grooves in its exterior, a cutter blade slidably mounted in each Vgroove and having an outer longitudinal scraping edge parallel to the body axis, the leading faces of each groove and-cutter blade and said scraping edge lying in the same radial plane extending from said axis, the exterior ot each blade being bevelled in a direction away from said scraping edge, spring means ineach groove for moving each blade bodily outwardly with its scraping edge maintained in said plane generally parallel to said axis and yieldably in engagement with the wall of a well casing during operation of said casing scraper therewithin, and stop means for limiting the extent oi' such outward movement.

8. A rotary casing scraper as dened in claim 7, the leading face of each groove having a notch extending from the bottom of the groove to the exterior o! the body.

REUBEN C. BAKER.

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