US2867280A

US2867280A - Scratcher construction for abrading well bore holes

Info

Publication number: US2867280A
Application number: US481559A
Authority: US
Inventors: Jarnett Frank Daniel De
Original assignee: PAUL A MEDEARIS
Current assignee: PAUL A MEDEARIS
Priority date: 1955-01-13
Filing date: 1955-01-13
Publication date: 1959-01-06
Anticipated expiration: 1976-01-06

Description

Jan. 6, 1959 F. D. DE JARNETT SCRATCHER CONSTRUCTION FOR ABRADING WELL BoRE HOLES Filed Jan. 1s, 1955 5 sheets-sheet 1 IN V EN TOR.

Jan. 6, 1959 F. D. DE JARNETr 2,867,280 SCRATCHER CONSTRUCTION FOR ABRADING WELL BORE HOLES 5 Sheets-Sheet 2 Filed Jan. 13, 1955 ,fem/z .0. .0f JAW/V527 y INVEN TOR.

:rive/V5# Jan. 6, 1959 F. D. D JARNETT scRATcHER CONSTRUCTION Foa ABRADING WELL BoRE HOLES 5 Sheets-Sheet 3 Filed Jan. 13, 1955 z ,a wwf/y mwy ,MJ s www l w l.. J# KN H -Fr Wl. 4 1 J l im w n. ww s y? M m 5 o IM rrlr. y W, w

Jan. 6, 1959 w F. D. DE'JARNETT SCRATCHERv CONSTRUCTION FOR ABRADING WELL BoRE HOLES Filed Jan. 15, 1955 5 Sheets-Sheet 4 AMMMMHHHHUUWWW prive/w54( Jan. 6, l959' F. D.v DE JARNETT 2,867,280

SCRATCHSR CONSTRUCTION FOR ABRADING WELL BOREHOLES SCRATCHER CONSTRUCTION FOR ABRADING WELL BORE HOLES Frank Daniel De Jamett, Long Beach, Calif., assigner of one-half to Paul A. Medearis Application January 13, 1955, Serial No. 481,559

13 Claims. (Cl. 166-173) This invention relates to a means and a method for the conditioning of an oil well bore involving the use of scratcher elements to abrade the mud cake away from the wall surface of the bore.` As disclosed in the Wright Patents 2,338,372, 2,374,317 and 2,302,352,`it isa Well known practice to use scratcherelements in thev form of numerous spring arms of wire or the like on a string of casing to abrade the mud cake away from a bore hole wall in preparation for forming a cement plug or bridge around the casing at some selected level. If the mud cake is not removed to permit the cement to bond directly with the Virgin earth formation the cementing operation will fail of its purpose to provide an etective huid-tight seal.

For example, in a well bore extending to a depth of 12,000 feet it may be desirable to seal off the bore hole around the casing by means of cement in a zone below the 10,000 foot level. To prepare for the cementing operation, the string of casing is lowered into the bore hole with suitable scratchers mounted at appropriate positions within the bottom 2,000 feet of the casing. When the scratchers reach the 10,000-12,000 foot zone the casing is either reciprocated longitudinally or rotated to cause the scratchers to abrade away the mud cake from the surrounding bore hole Wall. The dislodged mud cake is washed to the surface by forcing suitable kfluid ldown through the casing to flow upward to the surface around the outside of the casing. When the selected zone is cleared of mud cake, cement slurry is forced downward through the casing to flow upward around the casing to seal the Zone. v

A difficulty arises, however, because the usual scratchyers such as disclosed in the above-mentioned patents, tear mud cake away from the wall of the well bore all the way down from the surface to the selected zone. One result of using the scratchers unnecessarily for the distance of 10,000 feet is that the scratchers are worn and damaged by the time they reach the selected zone. Another result is that tons of mud cake that need not be disturbed are dislodged above the selected zone and must be washed out of the well at considerable cost in time `and labor. Because of the necessity of washing out this mud dislodged at the higher levels it is not feasible to lower the scratcher-equipped casing to the selected zone without pausing for washing operations at various levels.

The usual procedure for cementing such a 12,000 foot bore hole in the 10,000-l2,000 foot Zone is to lower the scratcher-equipped casing through the first 5,000 feet and then pause. The tons of filter cake dislodged in the first 5,000 feet is then washed to the surface by, pumping uid down through the casing and up to the surface around the casing. This pumping operation is continued until the uid is clear of dislodged mud cake and the time required for this pumping operation may be, for example, on the order of two hours. The casing is then lowered an additional distance, say 3,000 feet to the 8,000 foot level, and pumping is resumed for another two hours or so. Again the scratcher-equipped casing is lowered,

2 y Sayanofher 2,000 feet to the 10,000 foot level and the pumping operation is again resumed until the uid reaching the surface is clear of dislodged cake. When the scratchers are nally ylowered to the selected zone below y the 10,000 foot level, the casing is reciprocated and/or rotated to cause the scratchers on the casing toabrade away the mud cake for exposure of the virgin earth for` mation. The pumping is again resumed until the returning fluid is clear of foreign material. The well bore is then in proper condition for the usual cernenting operation.

` The general object of the present invention is to avoid v unnecessary wear and damage on the part of the scratcher elements'. An additional object of the invention is to save time and labor by mounting the scratcher elements on the casing in a retractible manner and byfurther providing an arrangement which permits the scratchers to be extended from retracted state whenever desired by remote control exercised at the top of the well. The invention makes possible a simple procedure in which the casing is lowered into the well bore with the scratchers `thereon retracted and then the scratchers are extended into initial contact with the wall cake by remote control when, and not before, the scratchers descend to the selectedzone. The casing isthen reciprocated longitudinalli and/ or rotated to cause the scratchers thereon to scour-the`well bore wall free of mud cake and iuid is pumped in the usual manner to carry the dislodged cake to the surface. In this manner the scratcher elements are conserved until they reach the selected area and the time and labor rrequired for clearing the well bore of dislodged mud cakev is reduced as much as or more.

In general the broad object of the inventionis achieved by providing means responsive to rotation of the casing to cause the scratcher elements to extend from their retracted positions to their extended effective positions by remote control when desired. With the scratcher' 'elel ments retracted, it is a simple matter to lower the casing into the well bore tothe desired level and then to rotate the casing t'o cause the scratcher elements thereon to extend into initial abrading contact with themud-coated wall of the bore hole.

The preferred practice of the invention is characterized' by the provision ofrotary means on the casing engageable with the borehole wall. Such rotary means, for example, may be provided vwith yielding vspring-like elements for frictional engagement with the bore holewall yto tend to keep the rotary means from rotating. such an arrangement, relative rotation between the rot-ary means andthe casing may be caused at any desired depth simply by rotating the casing inthe bore hole.V In accord with the teachings of the present invention, `the scratcher elements are constructed and arranged to extend from their retracted state in response to this relative rotation. Y

A feature of the preferred practice of the invention is the use of centering springs on the rotary means. These springs not only serve their primary purpose of frictional- 1y engaging the Wall of the well bore to'oppose rotation of the rotary means but also serve the purpose of centering the casing and scratcher elements in the well bore.

Preferably the scratcher elements are provided in the form of scratcher units, there being a multiplicity of wirelikeor rod-like scratcher elements on each unit. The

Patented Jan. 6,

With p casing may be manipulated longitudinally to shift the scratcher unit away from the rotary means. Thus a longitudinally movable scratcher unit may be positioned on the casing closely adjacent to'a fixed scratcher unit with both units heldin retracted state by the same rotary means..

When the two units are lowered. to the desired zone andare extended from their retractedv states, the movable 'unit maybe shifted longitudinally to a desired spacing vention will be apparent in the following detailed description considered with the accompanying drawings.

Y In thedrawings, which are to be regarded as merely illustrative:

Fig. 1 is a side elevation of a portion of a string of casingy equipped with one embodiment of the invention,

the casing being shown in a bore hole and the scratcher units thereon being shown in retracted state;

Fig. 2 is a similar view showing the scratcher units in extended 'effective state;

Fig. 3 isa longitudinal axial section on an enlarged scale taken as indicated by the line 3 3 of Fig. l;v

Fig. 4 is a fragmentary section similar to Fig. 3 showing two of the scratcher units positioned close together when initially extended to their effective states;

Fig. 5 is a transverse section taken asfindicated by the lineS-FS of Fig. 3;

Fig. 6 is a transverse section taken as indicated by the line 6-6 of Fig. 3; f

Fig. 7 is a fragmentary section taken as indicated by the line 7-7 of Fig. 6 showing the construction of a detent means that may be incorporated in a downwardly movable scratcher unit;

Fig. 8 is a similar view of a reversed detent means that may be incorporated in an upwardly movable scratcher unit;

Fig. 9 is a fragmentary longitudinal sectional view showing a modification of this first embodiment of Vthe invention; d

v Fig. 10 is a view similar to Fig. 1 showing a second embodiment of the invention with the scratcher units on the' casing in retracted state;

Fig.l 1l is a similar view showing the scratcher units in extended effective state;

Fig. 12 is an enlarged fragmentary sectional view of the embodiment of the invention shown in Figs. l0 and l1; Fig. 13' is an enlarged fragmentary longitudinal sectional view illustrating a third embodiment of the invenagee'aaso.

. a rotary means or rotary assembly, generally designated R, on the casing C and in this instance the rotary means straddles one of the collars 30. Thus the rotary assembly R in Figs. l and 2 comprises an upper rotary sleeve 32 above a collar 30 and a second lower rotary sleeve 34 below the collar, these two rotary sleeves being interconnected by a pluralityl of longitudinal bow springs 35.

The. upper ends of the bowy springs 35` are fixedly attached to a ring 36 that is slidingly mounted on the upper rotary sleeve-32 and the lower ends of the bow springs are attached: in similar manner to a ring 3S that is slidr` ingly mounted on the lower rotary sleeve 34. Each of the rings [36 and 38 has an integral spline 40 `(Figs. 3k and 5) which is slidingly mounted in a longitudinal groove 42 yin the corresponding 'rotary sleeve toprevent relative rotation between the bow springs and the sleeve. The bow springs 35 resiliently push outward to make frictional contact lwith the surface of the surrounding bore hole 44 as shown in Figs. 1 and 2 and arefree to expand to various diameters by virtue of the freedom given the

rings

36 and 38 for longitudinal movement relative to the two rotary sleeves. i

In this` first embodiment of the invention the rotaryassembly R cooperates with four scratcherfunits andholds the scratcher units in retracted state while the casing vC is being loweredl through the well bore.l lThe four scratcher units comprise an upper fixed scratcher unit 45 that is d stationary on the casing, an adjacent upper movable plurality of scratcher elements 52 in the form of spring tion wtih theV scratcher units on the casing in retracted Fig. 14 is a similar view with the scratcher unitsin extended effective state;

Fig. 15 Vis a fragmentary transverse'sectio'nal view taken as indicated by the line 15-15 of Fig. 13;

Fig. 16 is a View similar to Fig. 1 showing a fourth i embodiment of the invention;

gFig. 17 is an enlarged fragmentary longitudinal section taken as indicated by the line 17--17 of Fig. 16;'

Fig. V18 is a greatly enlarged fragmentary transverse i section taken as indicated by the line 18-18 of Fig. 17;

Fig. 19 is an enlarged portion of Fig. 16 with a portion of the latch structure broken away;

Fig. 20'is' a 'greatly enlarged fragmentary transverse i Fig. 21 is a view similar to Fig. 19 showing thescratcher .units in their extended state; and

Fig. 22 isa view similar to Fig. 18 showing a modifivcation of the fourth embodiment ofthe invention.

Figs. l and 2 show'avstring of casing-generally'desig- Anated C, comprising lengths of )pipe interconnected by collars `30. Il'hey invention contemplates'the frnounting of scratcher unit 46, a lower fixed scratcher unit 48 and an adjacent lower movable scratcher unit 5t?. j

Each of these four scratcher units is in the form of a ring or collar embracing the casing C and carrying a fingers of wire-like or rod-like character. The base of each of the-scratcher elements or spring fingers is suitably bonded'in position. Each of the spring fingers 52 is ypreferably formed with a coil 54 to provide a relatively wide range of flexure within its elastic limits. Eachof the spring fingers 52 is so `mounted and so coiled as .to tend to extend outwardly resiliently from the casing C into abrading contact with the surrounding wall of the well bore as shown in Figs. 2 and 4. Preferably, but not necessarily, each of the scratcher elements or spring fingers 52-is slightly bent at its tip as shown at 55 in Fig. 4.

The two fixed scratcher units 45' and 48 are immobilized on the casing C and the two movable scratcher units 46 and`50 are slidingly mounted on the' casing for movement longitudinallyl thereof. In the retracted state of the scratcher units while they are being carried downward through the bore hole by the casing, the upper movable scratcher unit 46 abuts the correspondingupper fixed scratcher. unit 45 and, in` like manner, the lower movable scratcher unitfiti abuts the lower fixediscratch-V er unit 48. Preferably'suitable yielding'means is providedto tend to maintaineach. ofxthe movable scratcher units in the abutting. relationshipV with the/corresponding fixed scratcher unit. For this purpose each oflth'elxed scratcher units `45 and 4S'mayy be provided with suitable spring clips 56 in lfrictional engagementwith the corresponding movable scratcher unit-46 orV 50. Prefer'- ably each ofthe movable scratcher units is slightly-recessed to facilitate engagement by the spring clips 56;

It is contemplated that each of the two rotary sleeves 32 and-34 will be mounted on the casing C by suitable lscrew threads. For this purpose a fixed cylindrical member 58 (Fig. 3) may be'mounted on the casing Cfor cooperation with the upper rotarysleevev 32 anda `second fixed kcylindrical member 60 may be mounted on the casing for cooperation with the lower rotary sleeve 34. As best shown in Fig. 3 the fixed cylindrical member 58 may be integral with the upper fixed scratcher unit 4 5 and the fixed cylindrical .member y641 may be integral with the lower-fixed scratchervunit 48, thetwo fixed cylindrical vaser/,aso

members being' bonded to' the casing by suitable welding 62.

The fixed cylindrical member 58 is snugly embraced by the corresponding upper rotary sleeve 32 and is formed With an external left-hand screw thread 64 for engagement by a corresponding left-hand internal screw thread 65 of the upper rotary sleeve. In like manner fixed cylindrical'member 60 is provided with an external right-hand screw thread 66 for engagement with a right-hand internal screw thread 68 of the lower rotary sleeve 34. Preferably each of the fixed cylindrical members 58 and 6@ is suitably recessed circumferentially to receive O-rings 70 for sealing contact with the inner circumferential sur- Aface of the surrounding rotary sleeve.

The upper rotary sleeve 32 has a cylinder 72 welded vthereto to form an upwardly extending cylindrical skirt 74 to serve as means for holding the two

upper scratcher units

45 and 46 in retracted state and, in like manner, the lower rotary sleeve 34 has a cylinder 75 welded 'thereto to form a downwardly extending cylindrical skirt '76 to hold the two

lower scratcher units

48 and 50 in Vretracted state. As shown in Fig. 3 each of the cylindrical skirts 74 and 76 embraces and contines the scratcher elements 52 of the corresponding scratcher unit, to hold the scratcher elements radially retracted or iiexed inwardly close to the peripheral surface of the casing C.

The casing C has a stop lug 78 welded thereon at a suitable distance above the normal position of the rotary assembly R to limit the upward longitudinal movement of the upper movable scratcher unit 46 and has a similar :stop lug 80 spaced below the normal position of the -rotary assembly R to limit the downward longitudinal movement of the lower movable scratcher unit 50. It is ycontemplated that each of the movable scratcher units `46 and 50 will be provided with suitable detent means that will permit the scratcher units to be moved longitudinally towards and against the corresponding stop lugs 78 and 80 but will prevent any substantial retraction away from the stop lugs. Thus after the casing C has been lowered into a bore hole each of the movable scratcher units may be shifted to a position abutting the corresponding stop lug and will thereafter be immobilized at the stop lug.

The detent means for the lower movable scratcher unit 50 may comprise al suitable small ball 82 mounted in a short longitudinal slot 84 on the inner circumferential wall of the unit as shown in Figs. 6 and 7. TheI slot 84 tapers in radial thickness as shown in Fig. 7, the slot at its lower end being less in radial dimension than the diameter of the ball 82 and at its upper end being greater in radial dimension than the ball. It is apparent that any tendency for the lower movable scratcher unit 50 to move downward longitudinally of the casing C will cause the ball 82 to tend to seek the upper portionl `of the slot 84 so that the ball will not interfere with the' -downward movement of the scratcher unit. On the other hand any tendency for the scratcher unit to move upward relative to the casing will cause the ball to seek the lower end of the slot with resultant binding of the ball to prevent such movement.

The corresponding detent means for the upper movable scratcher unit 46 shown in Fig. 8 comprises a similar ball 85 in a longitudinal slot 86 that widens in radial dimension towards the bottom of the slot. Suitable means is provided to continuously urge the ball 8S towards the upper restricted end of the slot 86. For this purpose the lower end of the scratcher unit 46 may be provided with a bore 88 in which is mounted a suitable plunger 90 in contact with the ball 8S. A suitable coiled spring 92 is confined in compression in the bore 88 between the plunger 90 and a threaded plug 94 to urge the plunger continuously upward. It is apparent that the arrangement in Fig. 8 will permit the upper movable scratcher unit 46 to be shifted upward against the upper stop lug 78, but that the ball 85 under pressure from the plunger will bind against the periphery ofthe casing 'to prevent return downward movment of the scratcherunit.

The manner in which this lirst embodiment of the invention serves its purpose mayy be readily understood from the foregoing description. While the casing C is being lowered into the well bore to bring the

various scratcher units

45, 46, 48 and" 50 to the selected zone or level in the well, the various movable parts are in the positions shown in Figs. l and 3. The upper movable scratcher unit 46 is releasably held in abutment with the upper iixed scratcher unit 45 by the corresponding spring clips 56 and in like manner the lower movable scratcher unit 50 is held in abutment against the lower fixed scratcher unit 48 by the corresponding spring clips 56. The upper threaded rotary sleeve 32 is threaded onto the left hand screw thread 64 and the lower threaded rotary sleeve 34 is threaded onto the lower right-hand thread 66 of the lower fixed sleeve 58.

The four bow springs 35 yieldingly press outward into frictional engagement with the surface of the surrounding well bore 44 to hold the well casing centered in the well bore. Thus with the

upper scratcher units

45 and 46 held in retracted state by the upper cylindrical skirt 74, and with the

lower scratcher units

48 and 50 held in retracted state by the lower cylindrical' skirt 76, and with the casing centered in the bore hole by the bow springs 35, it is apparent that the various scratcher elements 52 of the four scratcher units will be held out of contact with the surrounding bore hole.

When the four'scratcher units reach the selected zone in the well bore and it is desired that the scratcher units change from retracted state to extended effective state, it is merely necessary to rotate the casing clockwise to bring about the desired result. As the casing rotates clockwise the bow springs 35 frictionally engage the wall of the bore hole 44 to keep the rotary assembly R from rotating. Thus the casing C rotates relative to the two

rotary sleeves

32 and 34, the casing C rotating clockwise as viewed from the top of the well. This relative rotation causes'the upper rotary sleeve 32 to unscrew with longitudinally downward movement away from the two

upper scratcher units

45 and 46 until the upper cylindrical skirt 74 completely frees these two upper scratcherunits to permit their scratcher elements 52 to flex outward into contact with the wall of the surrounding bore hole as shown in Fig. 2. In like manner the clockwise rotation of the casing C causes the lower threaded rotary sleeve 34 to unscrew with a longitudinal upward movement until the lower cylindrical skirt 76 releases the two

lower scratcher units

48 and 50 to permit their scratcher elements 52 to flex outward into contact with the surrounding wall of the well bore. It is apparent that the provision for freedom for longitudinal movement of the two

sleeves

32 and 34 relative to the two corresponding splined rings 36 and 38 permits the required longitudinall freedom for movement on the part of the two sleeves that carries the cylindrical skirts 74 and 76 to their retracted scratcher-freeing positions. Thus the fact that the

rings

36 and 38 are slidingly keyed to the corresponding

rotary sleeves

32 and 34 serves a dualpurpose since it permits the bow springs 35 freedom for expansion into contact with the wall of the bore hole and at the same time permits the rotary sleeves to shift longitudinally to free the scratcher units.

Once the scratcher units are extended or expanded into abrasive contact with the surrounding well bore, the casing C may be reciprocated longitudinally to position the upper movable scratcher unit 46 against the upper stop lug 78 and to position the lower movable scratcher unit 50 against the lower stop lug 80. For this purpose the' casing C may tirst be moved longitudinally upward to position the lower scratcher unit 50 against the lower stop lug 80. As the casing is initially drawn longitudinally upward for this purpose, the engagement of the scratcher elements 52 of the lower scratcher unit 50 with the surface of the surrounding bore hole holds the mova lower ablerscratcher unit '.50 stationary: but the adjacent'fxed scratcher :-:unit:48= moves v`with f thelcasing and pulls the :clips-56;eut:ofengagement with the movable unitv 50. LThenscratcher-unitf 50 continues to be stationary until thelupward movement of the casing brings the lower stop lugf80 againstathe scratcher unit. When the casing C then -is fmoved `longitudinally downward, the :ball 82 binds against the-casingto immobilize the lower scratcher unit 50 on'the casingadjacent ,the lower stop. Thereafterthe stopikeeps the scratcher unit 50 from shifting on the casing in one direction and the detent keeps it from shitting inthe 'oppositer direction.

.1n like manner downward longitudinalmovement of the casing'C while the upperr movable scratcher unitr 46 is ,extended finto contact -withv the surroundingwell bore c `brings theaupper stop: lug .'78 against the scratcher unit .and thereafter rthebalVSSlbinds to, keepV the upper movable scratcher unit 46 frommoving away from the upper stopllug.- LWith ,the two movable .scratcher units 46 and v50'pnsitioned against :the corresponding stop lugs 78 and 80, longitudinal reciprocation of the casing will cause the two scratcher unitsy toreciprocate with Athe lcasing to abrade the bore hole toscour away the deposited mud cake. The longitudinal reciprocation of the casing will ,also cause-the'iixed scratcher units45 and 48 to reciproicate ,in the same manner.

Itisapparentthat the four scratcher units 457 46, 43

xand 50 maybe arranged to be spaced apart at various distances for this scratcher operation since lthe distance bet-weenthe two ixed-.scratcher

units

45 and 48 is a matter of choice and since the positioning of the stop lugs .'78 andv80 is a matter of choice.

Fig. 9 shows how the structure shown in Figs. l to 8 may be modified to cause the scratcher elements of'the two lowermost scratcher unitsto be retracted by upward exureinstead of downward flexure. in this construction the lower iixed scratcher unit 48a is integral with the carries an auxiliary outer cylindrical skirt 76h tovreceive :the ends of the upwardly extended scratcher elements of the adjacent lower `movable scratcherunit 50.

l'When both of the scratcher units 48a; and 50 are in .their retracted states the movable scratcher unit 50 is in abutment with the lixed scratcher unit 48a and is yieldingly held in this position by the usual spring clips w -56 as heretoforedescribed.

Thus the construction shown in Fig. 9 provides for allof the spring ngers or scratcher elements 52 to point or extend upwardwhile the scratcher .elements are being-moved downward through the bore hole. AThis provision is `furtherlinsurance againstv dame .age yto the' scratcher elements. yIt is apparent that in y .all otherfrespects the construction shown in Fig. 9 opcry ates in the same mannerrasy heretofore described.

. The secondembodiment of the inventionshown in Figs. to .12.includes three scratcher units comprising the previously mentioned upper fixed scratcher unit 45, fixed scratcher unit 48b corresponding to the previously described lower fixed scratcher unit 48, and a third still lower scratcher unit 96 which is of the usual collar or ring construction and is ixedly attached to the casing C by welding 98 (Fig. l2). The two scratcher units 45 and 48h are controlled by a rotary assembly in the manner heretofore described.

` The'rotary assembly in this second embodiment of the invention is largely identical as the first described rotary assembly indicated by the use of corresponding numerals to designate corresponding parts. In this instance, how` ever, a'relatively narrow cylinder 72b is `carried by the` upper rotary sleeve 32 to form a relatively short cylindrical skirt 741; for holding the -upper scratcher unit Ordinarily it will be t desirable to have thescratcher units more or less uni- =formly spaced along the casing.

-45l'in .retractedstate and-finglikeLmanner-a relatively short cylinder 75b is ycarried by the lower rotaryrsleev'e 34-to yprovide ay relatively short cylindrical' skirt76bfor holdingthe scratcher unit 48h in retractedstate.

The upper and'lower rotary sleevesSZ ,and 34 are threadedvontotthecasing by meansof correspondingfixed vthreaded sleeves as heretofore described. ThusFig. l2

shows the=lower rotarysleeve 34 threadedonto a corresponding cylindrical member60b that is welded onto the casing C. As shown lin Figi l2, the scratcher unit 48!) need not be integralwith'theiixed cylindrical member 60b. Thus thescratcher-.unit 48b.slidingly embraces the casing C but is substantially .immobilized relative thereto since it is coniined from above by the iixed cylindrical member 60b and is'confinedfrom below by stop means in the form of circumferential ywelding beads 100.

The third and lowerm'ost scratcher uniti 96 may be held in retractedl stateby any `suitable means that is operatively connected `withfthe lower rotary sleeve .34.

In the construction shown, the scratcher unit 96 is held in retracted state by a cylindrical skirt 102 that isformed by a ring 104. The ring 104 'slidingly embraces the casing C above-'the third scratcher unit'96 and is connected with the rotary sleeve 34 by means of a plurality of wires'or-pull rods 105. Thetupper end of each'of ythe pull rods 10S/extends through an apertured lug l106 on -the periphery of the cylinder 75 and thelower end of each of the pull rods extends through an apertured ylug -108 on the slidable ring l104. Preferably each end of each pull rodis lthreaded intora suitable litting 110 that is enlarged for engagement withl the corresponding apertured lug. Thus the fittings 110 may be rotated to adjust the eective ylength of the pull rods 105.

Figs. l0 and l2 showvfhowthe scratcher units of'this second embodiment of the invention are held in retracted state when the casing-isfbeing lowered through -the bore hole totheI selected zoneor level at which the scratching-operation is to be carried out. The upper skirt 74b holds thescratcher elements 52 of the upper lixed scratcher unit 45 in retracted or flexed state against the casing C; the lower cylindrical skirt 76b holds the scratcher elements 52 of-thelower xed scratcher unit 48b exed against the casing; and the skirt 102 of the ring 104 `holds the scratcher elements'52 of the lowermost scratcher unit 96 flexed against the casing. When -the three scratcher units reach the selected zone in the well bore.44 the casing C is rotated to cause the scratcher units 45 and 48b to be released in thefmanner heretofore described yfor extension into abrading contact with the surroundingwall of the bore hole as shown in Fig. l1. In the course of this operation the lower rotary sleeve 54 is shifted longitudinally upward by-screw-thread act1on and since this rotary sleeve is connected to the slidable ring `104 by thevpull rods 105 the cylindrical skirt 102er the ring l1041 is also shifted longitudinally upward to release the third scratcher unit 96' for extension 1nto abrading contact with thesurrounding wall of the bore hole. Y

.In the third embodiment of the invention shown in Flgs. l3to l5 the rotary assembly is of the usual construction comprising an upper rotary sleeve 114 threaded onto a fixed cylindrical member 115 andV a lower vrotary sleeve 116 threaded onto a corresponding fixed cylindrical-member 11S, the two xed sleeves being welded to the casing C as indicated. The two

rotary sleeves

114 and 116 have the usual longitudinal slots 'Each of the scratcherelements 122=is positioned between apair of radial .earsA 124.015 the scratcherunit and is 9 pivotally mounted on suitable means such as a wire 125. The pivot wire 125 is mounted in apertures in the radial ears and extends circumferentially around the scratcher unit. Each of the scratcher elements 122 is coiled around the pivot wire 125 and 4the inner end of each wire forms a control finger 126 by means of which the scratcher element may be rotated between a retracted position and an extended position.

In the contracted state of the upper scratcher unit 120 shown in Fig. 13, all of the control fingers 126 of the i various scratcher elements 122 extend into a circumfercntial groove 128 that is formed on the inner surface of a cylindrical member 130, the cylindrical member being mounted on the upper rotary sleeve 114 in overhanging position as shown. When rotation of the'casing C relative to the upper rotary sleeve 114 causes the upper rotary sleeve to retract longitudinally downward by screw-thread action to the position shown in Fig. 14 the downward movement of the cylindrical member 130 swings the control finger 126 of each scratcher element 122 clockwise to cause the scratcher element to swing to its extended or effective position shown in Fig. 14.

A second lower scratcher unit 132 is integral with the lower rotary sleeve 116 and comprises a plurality of scratcher elements 134 pivotally mounted on the rotary sleeve, Here again, the scratcher elements 134 may be spring wires individually mounted between spaced radial ears 135 and may be coiled to pivot on a circumferential pivot wire 136. Each of the scratcher elements 134 is formed with a control linger 138 that extends into a circumferential groove 140 on the casing C. In this instance the ycircumferential groove 140 is formed by the lower end of the fixed sleeve 118 in cooperation with a ring 142 spaced'therefrom, the ring 142 being welded directly to the casing C.

Fig. 13 shows the lower rotary sleeve 116 atan elevated longitudinal position with the control finger 138 of each scratcher element 134 in engagement with the upper wall of the groove 140 to hold the scratcher element in its upwardly directed contracted position against the casing C. When rotation of the casing C relative to the lower rotary sleeve 116 causes the lower rotary sleeve to unscrew downward. the downward movement causes the control finger 1158 to engage the lower side of the groove 140 as shown in Fig. 14 to swing the `control finger outward into its extended effective position as shown.

It is apparent that the embodiment of the invention shown in Figs. 13 and l5 may be lowered into the well to any desired level with the scratcher units in retracted state and that the casing C may be rotated in the well bore to cause the scratcher units to extend into abrading contact with the wall of the well bore 44.

The next embodiment of the invention shown in Figs. 16 to 20 involves the use of scratcher units that are positioned longitudinally of the casing and are intended to be operated primarily by rotation of the casing rather than by longitudinal reciprocation of the casing. In the construction showii there is an upper longitudinal vseries of spaced scratcher elements 144 constituting an upper scratcher unit designated by the bracket 145 and a similar lower longitudinal series of scratcher elements 144 constituting a second longitudinal scratcher unit designated by the bracket 146. The scratcher elements 144 of each of the scratcher units may be mounted on a corresponding longitudinal base plate 148 (Figs. 17 and 18) that is transversely curved to fit the periphery of the casing C and isA suitably bonded to the peripheral surface of the casing. As best shown in Fig. 18 each base plate 148 may be bonded to the casing by welding 150 along one longitudinal edge and by spaced welds 152 applied through spaced apertures.

The scratcher elements or abrading spring fingers 144 may be made of the usual heavy spring wire. In the construction shown, a single piece of spring wire forms two adjacent spring lingers 144. Each of the spring fingers spaced tongues 162 along one of its 144 is formed with a coil 154 at its base and the coils of` two adjacent spring fingers are interconnected by a U-shaped loop 155 of thewire, this U-shaped loop beingv suitably anchored to the base plate 148 as indicated at 156 in Fig. 18.

.The scratcher elements or spring fingers 144 are constructed and arranged to tend resiliently to extend substantially radially outward as shown in Fig. 19 for abrasive action on the surrounding wall of the bore hole. While the casing is being lowered into the borehole, however, suitable holding means is provided to releasably flex the spring fingers laterally against the periphery of the casing C. In this instance the holding means comprises van upper hinged leaf 158 for the upper scratcher unit 145 sigg a lower hinged leaf 160 for the lower scratcher unit Preferably both of the leaves on the casing C by piano-type this purpose each base plate 148 158 and 160 are mounted hinge constructions;A i For is formed with uniformly longitudinal edges and these tongues are curved to tubular configuration to embrace and hold a long pivot pin leaves 158 and 160 is formed with similar spaced tongues along one longitudinal edge for rotatable engagement with the pivot pin 164. Preferably each of the

leaves

158 and 160 is also provided with at leastone tongue 167 to serve as a stop to limit the outward swing of the leaf as shown in broken lines in Fig. 18.

. A feature of this embodiment of the invention is the concept of mounting thev upper leaf 158 in a manner per. mitting limited longitudinal movement on its pivot pin 164.

scratcher units under a single control such a be provided in the second scratcher unit. g Ipfs trliieg Egt; more than two the gaps will be required in all but the lowermost scratcher unit.

In this embodiment of the invention itis contemplated that suitable means under remote control will hold the upper leaf 158 in its closed position with the leaf at its lower limit position and that the leaf at this lower limit position will cause the lower leaf to be held in closed position. It is further contemplated that when the upper leaf is released to cause the upper scratcher unit 145 to extend into abrasive contact with the surrounding wall of the borehole, the upper leaf will release the lower leaf to permit the lower scratcher unit 146 to extend into abrasive contact with the wall of the bore hole. Instead of .arranging for the upper leaf 158 to overlap the lower leaf 160 for this purpose, I prefer to make the upper leaf longitudinally movable over a limited range as just de-l scribed and to provide a suitable latch means for the lower leaf under control of the upper leaf.

The required latch means between the leaf 158 and the. leaf 160 is generally designated by numeral 170 and may be constructed as best shown in Figs. 19 and 20. A latch housing 172 of hat-shaped cross-sectional configuration is welded onto the surface of the casing C to provide a longitudinal channel in which a suitable latch member 174 is slidingly mounted. To keep the latch member 174 from escaping from the channel the latch member may be provided with a pin 175 that extends through a longitudinal slot 176 in the latch housing.

The lower end of the upper leaf 158 is cut at a slant to provide a tip 178 which extends into the upper end of the latch channel as 4shown in Fig. 19 when the upper leaf is at its lowermost position. It will be noted in Fig. l1,9 that the tip 178 abuts the upper end of the latch mem- 174 and holds the latch member at its lower limit.

asanaao position. The :lower end of .the `latch member 174 is beveled to form an overhanging lip 180, which lip may hol'd the lower leaf 160 in closed position as shown in Fig. 19.

It is apparent that when the two

leaves

158 and 160 in their closed positions hold the spring fingers 144 flexed against the casing C as shown in Fig. 18, the spring fingers in their resilient tendency to swing outward create substantial pressure against the two yleaves that tends to cause the twoleaves to swing outward. A feature of the construction shown in the drawings is that a certain cam action is provided to utilize this force for shifting the upper leaf 158 from its lower limit position'to its upper limit position and also for shifting the latch member 174 from itsy lower limit position to its upper limit position. For this purpose the lower edge 182 of the upper leaf member is curved towards .the tip 178 as shownin Fig. 19"and,it is for this purpose that the lip 188 at the lower end of the latch-member 174 is beveled.

AAs may be'understood by reference to Fig. 19, when theupper leaf 158 is released to swing outward from its normal closed position, the curved lower edge 182 of the leaf slides along the upper end of the latch housing 172 with a cam action that shifts the `whole leaf upward and lifts its tip 178 out of the latch-channel. This upward retraction of the tip 178 permits the latch member 174 to shift upward and the latch member 174 shifts because the outward movement of the lower leaf 160 against the inclined inner surface of the latch lip 180 lifts the latch member with a cam action.

Any suitable means responsive to rotation of the casing C lmay be provided to releasably hold the upper leaf 158 in its closed position. For this purpose the present embodiment of the invention employs a rotary assembly as heretofore described comprising a pair of longitudinally spaced rotary sleeves 184 that are threaded onto the casing C by means of corresponding inner cylindrical members 163 and are operatively interconnected by bow springs 185. In the usual manner the opposite ends of the bow springs are anchored to rings 186 which are slidingly keyed on the 'corresponding rotary sleeves 184.

`T he lower rotary sleeve 184 has a cylinder 188 welded thereon to provide a lower cylindrical skirt 190. 1 A suitable ring 192, which may be termed an abutment ring, is

welded inside the cylindrical skirt.

`When the casing is lowered into the well bore, the lower hinged leaf 160 is heldin closed position by the latch member 174 as shown in Fig. 17 and the upper leaf 158 is held in closed position by the cylindrical skirt 190 of the rotary assembly. The tip 178 at the lower end of the upper leaf yextends into the latchthousing 172 to hold the latch member 174 at its lower effective position.

`When the scratcher units I145 and 146 reach the level selected for the cementing operation, the casing C is rotated to lcause the lower rotary sleeve 184 to retract longitudinally upward until the upper leaf 158 is released. The spring fingers of the upper scratcher unit 145 then swing the upper leaf outward with a cam action that lifts the leaf bodily to its upper limit position. When the tip L178 at the lower end of the upper leaf is free from the latch Ihousing 172, the latch member 174 is moved upward by the cam action of the upper end of the lower leaf 168 as the lower leaf is swung outward by the spring fingers 144 of the lower scratcherunit 146.

Fig. 22 indicates how this last embodiment of the invention may be modified by coiling the spring wire of the scratcher fingers around the pivot pin 164. Each spring finger 1.44ct is directly attached to a leaf 158a as indir cated at 194.

t My description in specific detail of the selected embodiments-of the invention, `by way of example and to illustrate the principles involved, will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

1 'Ik'.claim:

. 1. In oil well1productionfequipment, the combination comprising: a casing toextend "into a .Well bore; a Yplurality of spring ,fingersrnounted on said casing to swing between outwardly extendingefiective positions to abrade the surface ofy the well 4bore and retracted positions spaced inwardly from the surface of the well bore; yielding means .rotatably mounted on said casing for frictional engagement with the well bore; a sleeve rotatably 'surrounding and axially movable on said casing; means fixed on said sleeve movable axially alongsaid casing to a position holding said fingers lin a retracted position; key means vto vmaintain said sleeve in a substantially xed rotatable but movable axial position relative to said yielding means; and corresponding mating helical screw threads on said casingl and on said sleeve ftocause axial movement of said sleeve and .said finger holding means on said casing to release said fingers by rotation of. said casing with krespect to vsaid yielding means.

2. The invention as defined in claim l, wherein lsaid key means includes, an axially extending slot in said sleeve yand an axially extending spline on said yielding means to fit in said slot.

3. In oil well production equipment, the combination comprising: a casing to extend into a well bore; two

sets of spring fingers mounted at ytwo points on` said.

casing to swing between outwardly extending yeffective positions to abrade the surface 'of a well bore and .retractedpositions spaced inwardly from the surface ofthe well bore; yielding means rotatably mounted on said casing `for frictional engagement with the well bore; ya sleeve for each of said sets of spring fingers rotatably surrounding and axially movable on said casing; means fixed toeach of said sleeves movable axially along lsaid Icasing to a position l,holding a corresponding set of 'said spring fingers in their retracted position; key means to maintain each of said sleeves in a substantially fixed rotatable but movable axial position relative to said yielding means; and corresponding mating helical screw threads on saidsleeves and on said casingl at ytwo different points, one ofthe threads on said casing and a corresponding sleeve being opposite the other on said casing and corresponding one on the other of said sleeve, whereby said spring fingers may be released by rotationof said casing to cause said sleeves'to move axially and thereby release corresponding sets of said spring fingers.

4. The invention as defined in claim 3, wherein two sets of each of the means specified in claim `3 are provided to abrade the bore of the well and to centralize each set of spring fingers both in an efficient manner.

5. The invention as defined in claim 1, wherein an additional sleeve isffixed to sail holding means at a position spaced from said holding means around said casing; wherein a second/set of-spring fingers is fixed-to said casing at a position approximately the same as said second sleeve; land wherein a linkage is -provided between said second sleeve and Asaid holding means, said second sleeve being adapted to ret-ain said second set of spring fingers in their'inoperative positions, whereby said second set of spring vfingers may be released substantially simultaneously with the release of said first named set of spring fingers.

6. The invention as defined in claim l, wherein said sleeve `is provided with aplurality of axial grooves having pins extending -across corresponding groovesV through a body portion of said sleeve; wherein said sleeve is also provided with a circumferential groove, andl whereingsaid spring fingers include wire scratching elements having inner ends looped around vcorresponding pins and extending into said circumferential groove to retain them kin their operative abrading positions on said casing.

7. In oil well production equipment, the combination of: a casing to extend into a well bore; rotarymeans mountedon said casing for lrotation relative thereto and also for longitudinalzmovement relative thereto between a first position` anda rsecond position; -means including 13 screw threads on the rotary means and on the casing to retain said rotary means against longitudinal movement relative to the casing at its first position on the casing, said retaining means being releasable in response to relative rotation between the rotary means and the casing; a scratcher unit mounted on said casing for longitudinal movement thereon between a first position and a second position in response to longitudinal movement of said rotary means from its first position to its second position, said scratcher unit having scratcher ngers to abrade the well bore wall; means to hold said scratcher fingers retracted from the bore hole wall Iat said lfirst position of the scratcher unit; means on said rotary means for yielding engagement with the bore hole wall to resist both rotary and longitudinaltmovement of the rotary means in the well bore, whereby with said rotary means retained at its rst position and said scratcher unit at its first position with the scratcher fingers retracted, the casing may be lowered into the bore hole to place the scratcher unit at a desired level and then the casing may -be rotated to release the rotary means from said retaining means and then the casing may be moved longitudinally to cause longitudinal movement of the rotary means from its first position to its second position thereby to place the scratcher unit at its second position with said scratcher ngers extending into contact with the surrounding well bore wall; and detent means to prevent movement of said scratcher unit relative to said casing in a direction from the second position of the scratcher means towards its first position.

8. The invention as defined in claim 7, whereby stop means are additionally provided on said casing to limit relative longitudinal movement of said scratcher unit at its second position whereby said detent means may cooperate with said stop means to immobilize the scratcher unit relative to the casing at the second position of the scratcher unit.

9. In oil well production equipment, the combination of: a casing to extend into a well bore; rotary means mounted on said casing for rotation relative thereto and also for longitudinal movement relative thereto between a first position and a second position; means including screw threads on the rotary means and on the casing to retain said rotary means against longitudinal movement relative to the casing at its first position on the said casing, said retaining means being releasable in response to relative rotation between the rotary means and the casing; a scratcher unit mounted on said casing for longitudinal movement thereon between a first position and a second position in response to longitudinal movement of said rotary means from its rst position to its second position, said scratcher unit having scratcher fingers to abrade the well bore wall; means to hold said scratcher lingers retracted from the bore hole wall at said first position of the scratcher unit; means on said rotary means for yielding engagement with the bore hole wall to resist both rotary and longitudinal movement of the rotary means in the well bore, whereby with said rotary means retained at its first position and said scratcher unit at its first position with the scratcher fingers retracted, the casing may be lowered into the bore hole to place the scratcher unit at a desired level and then the casing may be rotated to release the rotary means from said retaining means and then the casing may be moved longitudinally to cause longitudinal movement of the rotary means from its first position to its second position with said scratcher fingers extending into contact with the surrounding well bore wall; and detent means to prevent longitudinal movement of the scratcher unit relative to the casing in the direction from the second position of the scratcher unit towards its first position.

l0. In oil well equipment, the combination comprising: a casing to extend into a well bore; a first set of spring fingers mounted on said casing to swing between outwardly extending effective positions to/ abrade the surface of a well bore and retracted positions spaced inwardly from the surface of the well bore; a ring slidable on said casing; a second set of spring fingers mounted on said ring to swing between outwardly extending eective positions substantially parallel with said first set of spring fingers to abrade the surface of a well bore and retracted positions spaced inwardly from the surface of a well bore; yielding means surrounding said casing for frictional engagement with the well bore; a sleeve mounted in a position to surround both of said sets of spring fingers and in a position firstly to release said second set of spring fingers and secondly to release said first set of' spring fingers successively in response to manipulation of said casing in a manner to move it relative to said yielding means and said sleeve; a radial projection on said casing spaced from said first set of spring fingers to prevent relative movement of said ring on said casing beyond a predetermined distance from said first set of spring fingers; and detent means to prevent movement of said ring along said casing in a direction opposite the direction of said projection from said first set of spring fingers.

ll. In oil well equipment, the combination comprising: a casing to extend into a well bore; first sets of upper and lower spring fingers mounted on said casing at two points to swing between outwardly extending effectivepositions to abrade the surface of a well bore and retracted positions spaced inwardly from the surface of the well bore; an upper ring slidable on said casing in a direction upwardly from said first set of upper spring fingers; a lower ring slidable on said casing in a direction downwardly from said first set of lower spring fingers; a second set of upper spring fingers mounted on said upper ring to swing between outwardly extending effective positions to abrade the surface of a well bore in the same direction as said first set of upper spring fingers and to retracted positions spaced inwardly from the surface of the well bore; a second set of lower spring fingers mounted on said lower ring to swing between outwardly extending effective positions to abrade the surface of a well bore and retracted positions spaced inwardly from the surface of the well bore; yielding means extending around said casing for frictional engagement with the well bore; an upper sleeve threaded to said casing and surrounding both of said upper sets of spring fingers to move downwardly and release said second set of upper spring fingers rstly and to release said first set of upper spring fingers secondly upon movement downwardly along said casing, said upper sleeve having a longitudinal keyed connection with said yielding means to move downwardly in response to rotational movement of said casing in a predetermined direction relative to said well bore, said yielding means maintaining said upper sleeve in a fixed circumferential posi-.

tion with respect to said well bore; a lower sleeve threaded to said casing and surrounding both of said lower sets of spring fingers to release said second set of lower spring fingers firstly and to release said first set of lower spring fingers secondly upon movement upwardly along said casing, said lower sleeve having a longitudinal keyed connection with said yielding means to move upwardly in response to rotational movement of said casing in said predetermined direction relative to said well bore, said yielding means maintaining said lower sleeve in a fixed circumferential position with respect to said well bore; an upper radial projection on said casing above said upper ring to prevent movement thereof beyond a predetermined distance above said first set of upper spring fingers; a lower radial projection on said casing below said lower ring to prevent movement thereof below a predetermined distance below said first set of lower spring fingers; detent means carried by said upper ring to`prevent movement thereof in a downward direction on said casing; and detent means carried by said lower ring to prevent movement thereof in a direction upwardly on said casing. t

12. An oil well tool comprising: a casing to extend into A1'5 a wellbore; a1plura1ity of nspring ngersfmounted on said casing to `swing between outwardly extending eiective positions to abrade vtllelsurface of the well bore and retracted positions `spaced'inwardly from the :surface of the well bore;,means on.said casing for frictional `engagement with the well boreyrneans connectedtofsaid frictional engagement means in a fixed rotatableposition and movable axially along said casing `from a position holding said ingers in a retracted position to a-positionvreleasing said fingers; .and corresponding mating helical-type screw threads on said casing and on-said finger holding means to cause axial movement of said nger holding means on said casing to release said ngersby rotationv ;of ssaid.

casing relative to said frictional engagementmeans.

13. An oil Well tool comprising: :a casing to extendinto a well bore; first and secondi sets of. spring ngers mounted at two points on said-.casing to swing between outwardly extending effective positions to abrade the surface of the well bore and .retracted positions `spaced,inwardly from the` surface Vof the well bore; and Ameans to hold each ofk said sets `of spring fingers in their retracted positions, said holding means including corresponding iirst and second cylindricalmeans to conne each of said sets of f 1 6 spring lingers and means connected .to said cylindrical means for frictio-nal kengagement .with the wellk bore to `prevent rotational movement ,of saidcylindrical means with respect thereto, said casing and yeach of-said cylindrical means beingpprovided with corresponding mating helical-type screw threads, the screw threads of said iirst cylindrical means being of a reverse pitch of the screw threads of said second cylindrical means, whereby both said first and second cylindrical means may be moved in oppositefdirections ,to return said first and second sets of ingers'to their effective ypositions simultaneously in-response to rotation of saidfcasing relative to said fric/tional engagement means.

References Cited in thele of this patent UNITED STATES PATENTS 2,157,493 Milleret al May 9, 1939 2,216,674 Miller et al. Oct. 1, 1940 2,311,768 McCray Feb. 23, 1943 2,482,985 Lockwood Sept. 27, 1949 2,674,317 Kipper Apr. 6, `1954 2,704,579 Brown Mar. 22, 1955