[1]- 2 @ 9 4 1 9 7 8 5 United States Patent Office 2,941,785 ENPANSIBLE ROTARY DRILL BIT 5 Archer W. Karnm,-rer, FuUerton, Calif., assignor, by direct and wesne assignments, to Rotary Oil Tool Coin. pany, Buena Park, CaEf., a corporation of California Ffled Apr. 15, 1957, Ser. No. 652,852 10 9 Cialim. (Cl. 255-76) The present invention relates to rotary drill bits, and 15 more particularly to rotary drih bits of the - expansible type adapted to be lowered through well casing to drill or enlarge a well bore beloiv the casing to a gre@ater diameter than the inside diameter of the casing itself. Rotary drill bits of the expansible type ordinarily in20 clude a plurality of cutters disposed initially in retracted position, which are expanded outwardly to enlarg-@ a previo.usly drilled hole. The maximum size of the cutters. that can be used is limited by the necessity of disposing them in a retracted position to pass through the well 25 casing or into the previously drilled hole, or both. The s-ize of the cutters places restrictions on the extent that they can enlarge the previously drilled hole, and thereby limits the extent to ivhich they can be expanded ouavardly. Accordingly, it is an object of the present inventibn to 30 provide a rotary expansible drill bft having cutters that c . an occlipy a retracted position and which can be expanded outwardly to a greeler extent than was heretofore possible, to enlarge a previously diilled hole to a substantially greater diameter than heretofore. 35 Another object of the invention ig to provide a rotary expansible drill bit hiving a plurality of cutters capable of being nested adjacent one another when in retracted position, in which one of the cutters has a greater length than one or more of the other cutters to Dermit greater 40 outward expansion of all cutters for the purpose of enlargin.o the well bore to a greater extent, the cutter of greater length operating upon the full annular formatio.,i area between the wall of the cri.-inal hole and the wall of the enlar,-ed hole. 45 This invention possesses many otlier advantages, and has other objects which may be made niore clearly apparent from a consideration of a form in wbich it may be embodied. This form is shown in the drawings arcompanying and i'Orming part of the present specification. It 50 Will now be describ,-d in detail, for the purpose of illitstrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the -.ppe-.lded claims. 55 Referring to the drawings: Figure I is a longitudinal section, with parts shown in elevation, through an embodiment of the invention with the cutters in retracted position; Figure 2 is a view similar to Fig. I illustratingthe cut- 60 ters in their fully expanded position, taken along the line 2-2 on Fig. 3; Fi,aue 3 is a cross-section tak-en alon.a the line 3-3 on Fig. 1; Figure 4 is a view corr,-sponding to Fig. 3 illustrating somewhat diagrammatically, the cutters after they ha;@ (35 been expanded outwardly to their maximum extent; Figure 5 is a view similax to Fig. 3 i]Justrating - the,cutter arrangement on a known design, of drill bit; Figure - 6 is a view corresponding to Fig. 4 illustrating, 70 the maximum extent of outward expansion of the cutter arrangement disclosed in Fig. 5. Patented. June 21, 1960 2 As disclosed in the drawings, a rotary expansible drill bit A is provided which can be secured to the lower end of a string of drill pipe B extending to the top of a well bore, by means of which the drill bit is lowered through a string of well casing (not shown) to a region below the casing shoe (liot shown) where the hole enlarging operation is to commenco. The general type of expansible drill bit shown in the drawings is both illustrated and described in Patent No. 2 545,036, to which attention is invited for certain structur'al details which are not disclosed nor described herein in detail. T'he up ,per portion of t'no rotary drill bit consists of'a tubular mandrel 10 having an upper pin 11 threadedly colinected to the lower end of the string of drill pipe B. This w-andrel includes an upper kelly ordrill stem member 12 slidably spl'med to the main body 13 of the bit, as. by having a lower non-circular portion 14 of the keljy adaloted to be telescopically received in a companion,. soeket 15 formed ii the main bit body. The n@ a-,idrel 10 has a limited range of longitudinal mover@ient within the body 13, its do@,vnward movement being deterriined by engagement of the lower end 16 of th-. kelly Nvith an inwardly directed body shoulder 17, its upward r@iovement being liniited by engagement of an extemal shoulder or piston portion 18 of the kelly, which,. fits within a counterbore 19 in the body of the toot above its socket portion 15, with a cylinder head 20 secured to the body. TP@is cylinder head 20 constitutes the upper portion of a hydraulic cylinder 21 in which the piston@ IS operates, the cyliiider head having @an upper, outwardly directed fl,)nge 22- adapted to engage an iipwardly f ' acing, shoulder, 23 in the body to prevent downward movement of the head relative to the body' Upward movement of tlit, head 20 with respect to the body is prevented by one or inore split snap retainer rings 24 received wit-hin an internal groove 25 in the body and extendin.- across the upper end- of the cylinder head. The upper end of the body 13 is closed by an annular upper guide niciuber 26, incltiding a depending portion '@7 received within the, upper end of the body and adapted to rest upon or be disposed closely adjacent the retainer riiigs 24' This upper guide member has an upwardly, tap.-ring guide surface 28 in its flange portion 29 which. rests on the upper end of the body 13, the guide being ovably secured to the body by a split wire snap ring ro " 3@', wliicli may be round in cross-section, received withinPii intemal groove 31 in the body and also within an opposed extemal groove 32 in the guide itself, The ring30- may completely fdl the internal body, groove 31, but, wien disposed therein, only extends@ partiary into the -Uide groove 32@ such groove being of' sufficient lateral. depth as to permit the wire ring to be disposed completely therewidih-i wlien the giiide 26 is inserted into and removed from the upper portion of the bit body 13. When t@ic upper guide 26 is insei-ted in the body 13, the ring 30 is forced complet-,Iy within the groove 32 until the ring 30 coines opposite the body groove 31, wl-.ereupon it-can expand inherently otitwardly and be received partly within. the groove 31 and partly within the groove; 32, thereby releasably assemblibg the guide member 26 to the body, The tool body 13 has a plurality of expansible parts mounted on it, including cutter supporting members 361, 36a pivotally inounted in body slot 37 on hin.-c pins 33 secured to the body. Each cutter supporlink ir@eniber 36,@ 36a depends from a hinge pin 38 and terminates in a bearing supporting pin 60 inclined inwardly and down-, wardly. A side roller cutter 61 or 61a is rotatably @ mounted on each bearing supporting pin, being mounted. on anti7friction roller and ball bearing elements 62, 63 rollable,onthebearingsupportingpin6G., Theballbearing elements 63 lock-the@ cutters against end-@r-ise.mover.ment on the bearijig supporting piii 6o, as well as tra- ns- -'
[2]mitting axial and radial thrusts between each cutter and its associated supporting pin. The roller @bearing elements 62 transmit primarily radial thrusts between these parts. The manner of mounting the ball and roller bearing elements 62, 63 between the cutters alid bea-ring supporting pins and of retaining them in place is specifically described in the above-mentioned Patent No. 2,545,036, The cutter supportin.- members 36, 36a and cutters 61, 61a mounted thereon tend to occupy a retracted position substantially entirely with the confines of the main body 13 of the bit. These cutter supporting members and cutters are expandible outwardly to enlarge the sides of the well bore and to operate upon a formation shoulder C that the cutters produce in the lat-ter. To accomplish the expansion, each cutter supporting member 36, 3.6a has an inclined expander sulface 64 on its inner portion, below the hinge pin 38 which tapers in a downward and inward direction. Each expander surface terminates in a lock surface 65 formed on the cutter supporting member. The outward expansion is accomplished by producing relativelongitudinal movement between the mandrel 10 and the bit body 13, which will produce corresponding relative longitudinal movement between the cutter supporting members 36, 36a and a tubular member 66 of the mandrel. This tubular member includes a lower portion 67 slidable within a guide bushing 68 secured in a guide support 69 attached to the body and extending across the slotted region of the@ latter below the lock surface 65. Located initially above the guide 69 and below the hinge pins 38 and in cutter supporting member recesses 70 is a mandrel lock and expander 71 having its outer surface 72 adapted to engage the expander surfaces 64 and the lock surfaces 65. The lock and expander 71 may be formed integrally with the tubular member 66, the upper end of the latter being piloted within a socket 73 in the lower portion of the kelly 12. -An enlarged boss 74 on @the tubular member engages a downwardlv facin2 shoulder 75 on the kelly, the tubular member being held a.-ainst the shoulder by a suitable split retainer ring 76 snapped into an internal groove 77 encompassing the kery soclet 73 and engagin- a downwardly directed shoulder 78 formed on th, tubular member boss. Leakage between the boss 74 and the wafl of the kelly socket 73 is prev6nted by a suitable side seal in the form of a rubber 0 ring 79 disposed within a groove 80 in the kelly 12 and engaging the boss 74. The kelly 12 has a central fluid passage 81 therethroiagh communicating with the string of drill pipe B. Fluid pumped through this passage can pass @into an aligned central passage 82 in the tubular member 66 and tlirough a central nozzle 83 in its lower portion, wheteby drilling mud or similar fluid can be pumped down through the tool for the purpose of removing the cuttings from the well bore and flushing them up around the drill pipe to the top of the hole. Assuniing that the body 13 of the tool is elevated relatively along the tubular mandrel 10, the inclined expander surfa= 64 of the cutter supporting members wiH be shifted 'upwardly aloiag the lock and expander portion 71 of the tlibular member 66. During such upward shifting, the cutter supporting members 36, 36a and the cutters 61, 61a carried thereby will be pivoted about the hinge pins 38 and urged in an outward direction. Movement of the body 13 with respect to the tubular mandrel 10 can continue untu the cutters 61, 61a have been shifted outwardly to their fullest extent, as determined by engagement of stop shoulders 88 on the cutter supporting members 36, 36a with companion showders 89 formed in the body on opposite sides of each body slot 37. VIhen such engagement occurs, the lower end 16 of the kelly portion of the tubular mandrel 10 will engage the body shoulder 17, and the lock and expander 71 on the tubular, member 66 wiR be disposed behind and in engagement 2,941,785 with the lock surfaces 65 on the cutter supporting rnember 66. It is to be noted that the lock surfaces 65 on the @utter supporting member 36, 36a and the companion surfaces 72 on the lock and expander portion 71 of the tubular member 66 are substantially parallel to the axis of the drill bit, to prevent the reactive forces of the formation on the cutters 61, 61a from moving the latter inwardly. As a practical matter, it is preferred that the coengaging 10 lock s-arfaces 65, 72 be inclined slightly in a downward, direction toward the axis of the tool to insure release:.of the lock and expander portion 7-1 from the cutter supporting member 36, 36a when the latter and the cutters 61, 61a are to be shifted back to their retracted position. 15 The relative longitudinal movement between the tubular mandrel 10 and the body 13 of the tool for effecting outward expansion of the cutters 61, 61a is accomplished hydraulically. The counterbore 19 receiving the piston 1.8 of the drill stem member 12 is formed in the upper por20 tion of the body 13 to provide the cylinder 21 having a cylinder wall 90 extendi@ng from a lower shoulder 91, defining the bottom of the counterbore, to the location of the upper guide member 26. As was previously des-' cribed, this upper guide member 26 closes the upper end 25 of the body 13, and can also prevent foreign substajices from moving down into the body through the use of a suitable wiper ring 92, which may be in the form of a rubber or rabber-like 0 ring disposed in an intemal groove 93 in the upper guide and slidably and sealingly 30 engaging the periphery of the mandrel 10. The cylinder head 20, which is retained in the upper portion of the body cylinder 21, has an inner seal ring 94, in the form of a rubber or rubber-like 0 ring, received within an intemal groove 95 in the cylinder head and 35 slidably and seatingly engaging the periphery of the mandrel 10. This head 20 also has an external seal ring structure in the form of a rubber or rubber-like 0 ring 96 disposed in an external groove 97 in the head and sealingly engaging the wall 90 of the counterbore cylin40 der 21. 'rbe head 20 its6lf has a depending skir-t 98 engaged by the upper end of the piston portion 18 of the mandrel for the purpose of limiting the extent of relative upward movement of the mandrel 10 with respect to the body 13 of the tool. This skirt 98 is disposed at 45 the outer portion of the cylinder head 20 to provide an annular space 99 between the periphery of the mandrel or kelly 12 above the piston portion 18 and the skirt itself into which fluid under pressure from the central passage 81 of the mandrel can enter, such fluid flowing througli r'O intercommunicating lateral ports 100 in the mandrelimmediately above the piston portion 18. Fluid from the cylinder space 99 is prevented from passing downwardly around the periphery of the piston -tB by a suitable side seal ring 101, such as a rubber or 55 rtibber-like 0 ring, disposed in a piston groove 102 and sealingly engaging the cylinder wall 90. Fluid under pressiire in the string of drill pipe B and within the tubular mandrel 10 is fed into the cylinder space 99 through the side ports 100, such fluid under 60 pressure being developed by the back pressure built up throligh the necessity of the fluid to pass through the relatively restricted passage 82 through the tubular member 66 and the nozzle 83 at its lower portion. 'fhis back pressure imposed on the fluid in the cylinder space 99 65 acts in an upward direction on the cylinder head 20, urgmg the body 13 of the tool upwardly with respect to the tubular mandrel 10 and correspondingly elevating the cutter supporting members 36, 36a-@ and cutters 61, 61a with respect to the lock and expander portion 71 of 70 the t@ubular member 66, until the cutters 61, 61a are expanded to their fullest extent. Thus with the fluid pressure elevating the body relative to t@e mandrel, the tool can be rotated, the cutters 61, 61a operating -upon the formation and gradually being expanded outwardly as the 75 body continues to be elevated ai@ng the raandrel until
[3]2,941,7 6 the cutters have been expanded outwardly to their fullest extpnt, as determined by engagement of the cutter supporting arm shoulders 88 with the companion body shoulders 89. When this occurs, the mandrel and lock poraon 71 is disposed behind compan-lon lock surfac.-s 65 5 of the cutter supporting niembet 36, 30a, to retain the clitters 61, 61a in their outwardly expanded position, t@e dow.nw ard drilling Wei,-bt being tr@nsmitted from the 16wer end 16 of the keuy 12 to the body shoulder 17, a'nd from -the sto@ s4oulders 89 on the latter on opposite 10 sides of the slots 37 to the cutter supporting members 36, 36a, being transmitted from the latter through the cutt.ets 61, 61a to the formation shoulder C. -Ihe cutters 61, 61a will remain locked in their outwardly expanded position so lon.- as drilling we.@ght is being im- 15 posed upon the drill pipe B and the drill bit A, the cutters 61, 61a operating upon the forination shoulder C to pfogress ively enlarge the bore in a downward direction. During the driuing operation, a guide D of any suitable form, which is mounted on the lower portion of the 20 body 13, centers the dffll bit in the original hole E. When expanded, the cutters 61, 61a will produce the enlafged hole F. With the cutters 61, 61a in their outwardly expanded position, as disclosed in Fig. 2, down weight is imposed 25 thereon and the driff bit rotated through the drill pipe, the cutters operating upon the formation shoulder C and ejqlargin g the hole in a downward direction. AfLer the desired len.-th of hole has been enlarged, or the cutters have become worn, the tool may be retrieved from the 30 well bore by discontinuing the pumping of fluid therethrqugh and elevating the drill pipe B and the mandrel 10 attached thereto. Such actiori will elevate the lock portion 71 of the tubular niember 66 above the locl, surfaces 65 on the cutter supportin.- members 36, 36a, 35 allowinthe latter and the cutters 61, 61a carried thereby to move back to their retracted position, such as disclosed in Fi.-. 1. The tool may now be elevated in the w,ell bore and moved back through the well casing to the top of the hole. 40 In the type of tool iflustrated in the drawings, the bearing supporting pins 60 are disposed the same distance below the hinge pins 38, and aR of the cutter supporting member s 36, 36a and cutters 61, 61a are expanded outwardly to the same extent, to drill the enlarged liole F. 45 Heretof ore, the cutters 61, 61a have all been made alike, having the same cutter length and the sanie diameter. With the same length of cutter supporting member 36, 36a and the same size cutter, the cutters would each have a certain maximum length, as dictated by the lieed for 50 the cutters to be disposed in their fully retracted position substantially completely within the confines of the body 13, and by the fact that the cutters could only be lb.cated inwardly of the body to the point at which they did not interfere with one another. Such arrangenient 55 of cufters 61x is Wustrated in Fig. 5, the outer portions of the cutters being disclosed in relatioii to the diameter of the previously drilled hole E which is to be enlarged. With the cutter arrangement illustrated in Fig. 5, they can be expanded outwardly, as a practical matter, to in- 60 crease the radius of the hole by an atnount Nvhich corr(@spon ds to the length L of each cutter. That is to say, the length of the formation shoulder that is produced in the, weH bore could be no greater than the length L of inner waH of the drihed hole E to the inner wall of the ei4arged hole F'. This condition is illustrated diagrammatically in Fig. 6. If the cutters 61x were expanded outwardly beyond the extent indicated, then the inner epo4@ of the cutter teeth would be disposed outwardly of 70 the inner waR of the hole E, and wouldnot operate across 6-e ,f-a,ll- face of th-e formation shoulder C, which would iipped-e, prpgress of the bit through fauure to drin the Wq, or which would result in the failure of the bit to make any progress at all. 76 By -virtup of the pres,pnt invention, the cutters 61, 610 and the cdtter supporting members 36, 36a can initially occupy a i@-,tracted position substantially completely within the confines of the body 13 of the drill bit and can be expanded outwardly to a greater extent, in order to increase the size of the initial hole E to a much greater diametqr than heretofore, assurance, being had that thi@ drill bit cutters will operate upon the full face of the shoulder C produced between the inner wall of the orig@ inal hole E and the inner wall of the enlarged hole F, such as dis!z@losed in Figs. 2 and 4. In accomplishing the purposes of the present inven@ tion, one of the cu,tters 61a is made longer th,an the other cutters 61. That is to say, the other cutters 61 are shorter in length LI than the corresponding cutters 61x represented in Fig. 5, whereas the one cutter 61a is made longer in len,gth L2 than the corresponding cutter represented in Fig. 5, this latter cutter 61a extending inwardly to a further extent than the correspondin g cutter reprp@ sented in Fig. 5. The outer portions of all of the cuiters could be substantially the same, as illustrated in Fig. 2, such outer pqrtions lying within the confines of the body 13 when in retracted vosition. The cutters 61, 61a ar@ rangpd andproportioned as disclosed in Figs. I to 4, inclusive, can be expanded outwardly to a greater extent than the c utter arranizement and Pro ortions illustrated p in ti 5 pd to gs. I 0, enlarge thle size of the bore hole E to a greater ex ent. As shown in Figs. 2 and 4, the cutter supporting members 36, 36a and the cufters 61, 61a @?Lv@, bpp4 expanded outwardly to a greater extent than shown in Figi 6 to driu a hole F having a radips t hat is greater than the hole size F' bv the amount indicated:by the ietter G in Fig. @. In that figure, the circle F repreih rg, sen.ts , e size of the enla ed hole drilled by the cutter arrangement illustrated in Figs. 1 to 4 inclusive, wherea4 the letter F' indicates the size of the enlarged hole that can @e d prpd4ce by the cutter arrangement and prqportions shown in ]Fig. 5. The enlaraed hole F will be pro7 duced with the cutter 61a operatin upon the entire radial I 9 - eii@nt of t@e--s-h'o--ul-der C, extendin fro the wall of the g m ori,-inal hole E to the wall of the enlarged hole F. Su@b inere@ksp in e:@p,apsion of the cutters to drill the increa@ed hole size made Possible by the fact that the length of the cutter Olq @'s grpater than heretofore, so as to be cqpab e of ppera I ting upon a should er C that is substa ntially grpat r than was heretofore possible. The greater size hole will be T)roduced despite the factthat the lengtli of the cutters 61 has been decreased. As shown in Figs. @@no 4, the cutters 61 do aot operate upon the, inner an lar Portion H of the formation shoulder C. Desp@te this fact the inner annular portion H of the shoulder C is still,l bei,ng operated upqn by the inner portion of the teeth of the cutters 61a, as is clearly evident from Fig . 2 and 4. The cutters 61 cooperate with the, cutters 61a in p 9 by far the @reater proportion of the drilling action to enlarge the well bore from the size of the hole E to the size of the hole F. The amount of material that must be removed by the inner portiori of the cu@tter 61a alone, represented b the annulus H y in Fig. 2, is rel4tively small, and 'surh removal occtirs ivithout difficulty. it is, @ccordin ly, app4rent ti,@at a rotary drill bit has g been p@ovided in wbich tlle cutters can be expanded outwardly to a greate,r extelnt to correspondingly enlarge the as to the size of the well bore F, with a.-surance that all portions of the formation shotilder C lying between the inner waii of th, original hole E and the inner wall of the enlarged hole F will be acted upon by at least one cutter of the apparatus. A substantial increase in the size of the etilarged hole is thereby made possible, t@,e increase in the size of the enlarge@d hole being represented diagrammatically E@pd by wqy of example by the letter G in Fig. 6. Tlic inventor
