US2654575A - Tandem expansible rotary drill bit - Google Patents

Description

Oct. 6, 1953 A. w. KAMMERER TANDEM EXPANSIBLE ROTARY DRILL BIT 5 Sheets-Sheet l Filed Jan. 9, 1950 I INVENTOR. Alea/Eze WMMEQE@ T rjeA/Ex A. w. KAMMERl-:R 2,654,575

TANDEM EXPANSIBLE ROTARY DRILL BIT 3 Sheets-Sheet 2 TTQA/Ex INVENTOR. Qc/EQ WMMEQER,

Oct. 6, 1953 Filed Jan. 9, 1950 Oct. 6, 1953 A. w. KAMMi-:RER 2,654,575

TANDEM EXPANSIBLE ROTARY DRILL BIT Filed Jan. 9, 1950 5 Sheets-Sheet 3 yda. fifa.

larging the diameter of the bore hole to a. considerable extent. The lower bit B will enlarge the bore hole diameter to an intermediate size, whereas the upper bit A is capable of increasing the size of the bore hole to a greater diameter than that produced by the lower bit. Additional Vbits can be mounted in tandem fashion above the existing bore hole, as desired. As disclosed in the drawings, a pilot bit I is secured to the main body II of the lower expansible drill bit B, for the purpose of cutting a new hole or assist in centering the bit assembly in an existing hole. The cutters i2 of the lower expansible bit are adapted to form a shoulder E in the formation, and then operate upon such shoulder in a downward direction to form a bore hole F of increased diameter. The cutters I3 of the upper expansible bit A are adapted to form an annular shoulder G in the formation around the larger hole F produced by the lower expansible bit cutters I2, and operate upon such formation shoulder to form a well bore H of still further increased diameter.

The lower drill bit B is illustrated and described in my United States Patent No. 2,466,991, and in my application for Expansible Drill Bit, Serial No. 43,789, led August 12, 1948. The upper drill bit A is described and claimed per se in my application for Expansible Rotary Drill Bits, Serial No. 137,535, filed January 9, 1950.

The upper end of the lower expansible bit B consists of a driving mandrel I4 whose upper pin Y I5 is threaded into a box I6 formed at the lower end of the main body I'I of the upper expansible drill bit A. This lower mandrel I4 includes an upper kelly or drill stem member I8 slidably splined to or telescoped within the main body II or" the bit. As specically disclosed in the drawings, the exterior I5 of the kelly is hexagonal in shape, being telescoped within a companion hexagonal socket 2s within the body. The mandrel I@ has a limited range of longitudinal movement within the body I I, by virtue of engagement of an external shoulder 2I on the kelly I3 with a retainer ring 22 on the upper end of the body, which is suitably secured to Vthe latter, as by the use of welding material 23.

The lower body l I (see Fig. 7, particularly) has a plurality -of expansible parts mounted on it, comprising cutter Y supporting members 24 pivotally mounted in body slots 25 onpivot or hinge pins 2B suitably secured to the body. Each cutter supporting member 24 consists of a depending leg 2'! having a bearing supporting pin 28 inclined inwardly and downwardly, and on which a' roller side cutter i2 is rotatably mounted. Anti-friction roller and ball bearing elements 29, 30 are placed between each cutter I2 and bearing pin 28, in order to transmit the radial and axial thrusts imposed upon the cutter. The ball bearings 30 also retain eachcutter I2 on the pin 28, being inserted in place through a pasage 3l in the Ybearing pin, which is then clorsed'by a plug 32 welded to the pin. The plug or pin 32 depends from the passage 3| and is used torhold the cutters I2 in retracted position, as described below` Each cutter supporting member 24 also includes an upwardly extending arm 33 against which an elastic o1' compressed coil spring expander 34 bears. This expander is received within a retainer pocket 35 in the body I I, and exerts its force against the arm 33, tending to swing it inwardly and thereby urge the cutters I2, on the other side of the fulcrum pin 26, in an outward direction. The extent of this outward movement is limited by engagement of the cutter supporting member with shoulders 36 of the body on opposite sides of the slots 25, which shoulders function as stop members.

After the cutters I2 have been expanded outwardly by the expander springs 3d to the maximum extent, they can be locked in this position by a tubular member 31 of the mandrel I4, which member is piloted in the kelly it. This member 31 is provided with a lock portion 38 movable from an upper position in transverse alignment with recesses 39 formed in the supporting members 24, permitting retraction of the cutters I2,

to a lower position opposite lugs @t formed on and projecting inwardly from theV supporting member legs 27, preventing retraction of the cutters I2.

The tubular member 31 may be connected in swivel fashion to the kelly I8 to permit relative arcuate rotary movement therebetween, which can occur to a slight extent. However, the kelly I8 and tubular member 31 are coupled together for movement in both directions. rThis is accomplished by providing an anti-friction thrust bearing 4I between a boss or shoulder i2 on the tubular member 3l and the kelly I3. The shoulder [i2 is received Within a socket 43 in the kelly, and has a toroidal raceway 44 on its exterior around which a plurality of bearing balls 45 can be disposed. These balls are also received in an opposed torodal raceway 45 in the kelly i8.

The balls 45 are insertable into and between the raceways 44, 46 through a hole 4l extending through the external kelly shoulder 2I and communicating with the internal race 45. After the balls have been thus disposed in positiony the hole is closed by a suitable plug 48 which is prevented from moving outwardly of the kelly by the inner .wall of the surrounding body I I.

ymember by suitable packing 52j disposed between its boss 42 and the kelly I8.

Because of the swivel connection @.I, the kelly I8 andtubular member 3 are caused to move jointly in both directions, but they are free to partake of relative movement with respect to each other.

The mandrel I4 may normally be held in its upper position with respect to the main body II and the supporting members 25 by a helical retractor spring 53 encircling the tubular member 31, with its upper end engaging the mandrel shoulder 42 and its lower end engaging a spring seat 5e Yat the lower end of the hexagonal body socket 20. This spring seat 5d also serves as an upper bearing guide for the tubular member 31,

f whose lower end is slidable Ywithin a lower bearing guide 55 below the lugsV 48, which guide is integral with or secured to the main body of the bit.

The lower drill bit B may also be provided with latch device for retaining the cutters l2 initially in' retracted positions" against the expansible forces of the springs 34. This device includes a holding plate 56 secured to the lower end of a central rod 51 projecting upwardly into the tubular rnexnber passage 5|. The holding plate or member 56 has spaced holes 5t in its outer portion for receiving the lower ends of the ball bearing 'plugs 32. i

When the holding device is disposed over the plugs 32.V the cutter Supporting nernbers 2&1 are prevented from expand-ing under the iniluence of the compressed springs 34. thereby holding the cutters l2 in retracted position'. Release or the holding device 'can occur hydraulically through aid of a ball a9, which may be dropped dow-n the drill string C into engagement with the rod 5l, r which may be placed in the lower drill bit passage i prior to its disposition in the well bore.

During lowering of the apparatus through the Well bore; the b'all 59 may be lifted into the larger passage 59 through the kelly pin', for the purpose of allowing upward now of iluid through the bits B; A and drill pipe C-.

As explained below, when the point in the well bore has' been reached at which the rearning operation is to begin, the latch device 5S is eject'e'd hydraulically from the cutter mechanism, allowing the springs et to 'eiipand 'and urge the cutters I2 in an outward direction to enlarge the well bore;

, The lower expansible drill bit B will enlarge vthe well bore to 'a certain intermediate diameter. The upper expansible drill bit A 'can enlarge the well bore to a sti-ll greater diameter. As shown most clearly in Fig, 6, the main body il of this upper bit is secured to the mandrel it of the lower bit B by threading the upper body boit l onto the mandrel pin I5. upper tubular inandrel 68 is piloted within the upper body and has its upper end formed as a threaded @l which 'can be screwed into a sub '2 that cbnstit'ute's the lowermos't portion of the string of drill pipe C. The upper mandrel Gli includes an upper kelly or drill stem member 63 sliilably splin'ed to the main bo'dy of the bit, as by forming the exterior .G4 of the kelly of hexagonal 'shape and providing a 'corresponding hexagonal ysocket E5 in the b'o'tly. The mandrel 50 has a predetermined rang 'of longitudinal movement Within the body, its lipward movement being limited b'y engagement of an external shoulder S6 on 'the kelly with the retainer ring tl at the' up'per end of the body il, the ring being suitably secured to the latter, 'as by use of welding material eil.

rihe Aupper body il is provided with fa longitudinal transverse slot 59 'extending through it, in Ywhich a 'pair of opposed cutter slipportlng members iii are disposed. These 'cutter sup ort'- ing members have' their upper 'ends mounted fon pivot or hinge pins l! extending across the holly slot and suitably secured to the body. 'The cutter .supporting members or legs lil 'depend from these hinge pins to a substantial extent, each having a lower bearing supporting .pin l2 'on which a 'side cutter i3 is rotatably lilou-nte"d.v Antieriction roller and ball bearing lelements la., 'it `-are disposed between each bea-ring supporting pin l2 and cutter i3. to transmit the radial Tand axial bearing loads therebetween, the ball bearing-elewhit-h closed by a suitable plug 11B welded, or therwise suitably attached, :to the pini. The plugs F116depending'` rm'trie bearing pins .l2 :can be availed of for holding the supporting l'egs land Ycutters t3 Qin retracted position, as described iielowl.

The `ipp'ositely vdisposed bearing' supporting rnenbers and their cutters :may ioocupy retracted .positions substarnially entirely within the con- -nes .of the upper tbod-y H. They may be eX- 'apanded mrtwardly loaf the body to :a larger eiec'tive 'diameter 'than the maximum Vrearning diameter of the cutters i2 fof the lower bit B. expand- .i-ng theV upper cutters It, their supporting legs vlll Yare swung outwardly about the hinge ,pins ll to :a predeterminedezitent. v"The .device for expand- 'iing the upper vcmters `includes a lower tubular 'member il; forming part :of the upper mand-rel "60, and .piloted within a lower socket .78 in the kelly 263. The' kelly 6i3 andlower tubular member 153 `are assernbled together for joint longitudinal movement through a swivel connection T9 that is substantially the saine as `the swivel connection '4l between the lower kelly I8 and lower tubular member .31. This connection le enables the :upper kelly 6B and tubular member 'il tofsrii-ft angularly with respect Yto one another,y but vcouples Y.thern together for conjoint longitudinal movement in both 'directions The tubular member T1 `ext1=.r'1':l's` downwardly through a guide washer and stop elementilb, resting upon a 'shoulder iSl formed on the body.y This washer initially is disposed :below the lower end of the kelly t3. so as to allow the kelly 4and tubular member ll to be rnoved downwardly; for `the purpose vof holding the upper cutters i3 and their supporting members l0 ill an outward position. :in addition, the kelly -63 and tubular member il lresisst inward increment 'of the cutters i3 fro-rn their outward position; and, under some conditions of `:usage or the ediiipm'ent, can actually shift `tlf-1e `cutters i3 to their outwardly expanded posi'- 'tion. The tubular meinberll is also slidable in va lower guide 82 integral with the body, and forming a support for 'the tubular in'ember l?, to rresist ,its lateral movement; The lower end o the tubular vmember is also slidable in the body Ybox l5; communicating with the passage 50 in the lower mandrel i8.

The tubular member' 'I1 of 'the mandrel 'et also vhas a cup=shaped thrust head 83 intermediate .the upper and lewer guides Bt, E25 provided with a depending skirt 811 terminating above a thrust block 85 slid'abe along `the exterior of 'the tubular member ll below its skirt 84. 'Ihe block S5 has longitudinal slots 8S on opposite sides of the ina'ndrel in alignment with the cutter supporting Alegs la7 to carry a pin 8l on leach side ofthe mandrel 'on which the upper ends of inclined thrust links 8B are pivo'ted. The lpwer end of each link is attached t'o the cutter supporting member I0 by means of fa -lowei` pin .89, at a point 'which is intermediate the hinge pin Il and butter i3;

The upper `cutters 'i3 may b'e expanded outwardly upon v`downward movement of the drol with respeet te the body Il, which causes the lower end of the skirt B4 to engage the bl l; 85; shifting the latter downwardly and swinging the legs '10 outwardly about their hinge pins li, through the agency of the thrust links 8u. AIf 'desireety outward expansion 'of the upper cutters 13 and-their supporting legs' vlil may be accompli-shed by a helical compression spring 90s disposed with@ in the skirt 84 and bearing at its upper lend 'upon 7 the head 83 and at its lower end 'upon the thrust block 85. It is evident that this spring 90 tends to urge the thrust block 85 downwardly and the legsl in an outward direction.

The upper cutters I3 may be releasably locked in retracted position by a holding device, to insure the downward passage of the bit assemblage A through the casing, and the well bore below the casing, to the desired point at which the hole enlarging operation is to commence. This holding device may include a rod or eye element il! for each cutter threaded into the tubular member ll, and having a hole e2 receiving the lower end of the ball retaining plug 16. These elements 9| will prevent outward expansion of the cutters I3 until the elements are moved downwardly from the plugs 16, as by moving the tubular mandrel 6E) downwardly with respect to the body I1. The lower end of the mandrel skirt 84 is disposed a suflicient distance above the thrust block 85, when the cutters I3 are in their initial retracted position, to insure the downward removal of the lock or latch elements 9| from the plugs 'I5 before the skirt 84 can engage the thrust block S5. Without such relative positioning of the parts, it may be difficult, if not imposssible, to unlatch the cutters I3, since prior engagement of the skirt with the thrust block would preclude further downward movement of the mandrel @El within the upper body Il.

As noted above, the upper mandrel 50 is slidable in the threaded box I6 at the lower end of the bit body I1, leakage around the exterior of the mandrel being prevented by a suitable side seal 93 in a box groove 94 slidably engageable with the exterior of the tubular mandrel. Accordingly, the iiuid pumped down the drill pipe C can pass through the upper kelly passage 95 and the tubular mandrel 'passage Q5, for discharge into the lower kelly passage 50 and into the lower tubular member 3l, for the purpose of releasing the lower latch member 56, and thereafter discharging into the well bore to flush the cuttings to the top of the well bore.

The depending leg portions 2l of the lower cutter supporting members 24 are of such length as to enable the cutters I2 to be expanded laterally to a predetermined maximum diameter, in order to enlarge the well bore to an intermediate size F. The upper cutter supporting members or legs 'IQ are substantially longer than the lower legs 2l, to enable the cutter elements I3 to be swung outwardly or expanded to a greater effective diameter than the lower cutters I2, in order to obtain a still further enlargement H of the bore hole diameter. The extent of expansions of the respective upper and lower cutters I3, I2 is properly selected to insure the eiective operation of the drill bit apparatus in ultimately increasing the diameter of the bore hole to the required amount.

The drill bit apparatus is assembled with the upper and lower cutters I3, I2 in retracted positions, in the manner illustrated in Fig. 1,'and with the upper mandrel pin 6I threaded onto the lower end of the drill pipe C. The upper and lower latches SI, yS are in place, in order to lock the cutters intheir respective retracted positions. Y 1

rihe apparatus is lowered through the well casing (not shown) until it reaches the location in the well bore at which the hole enlargingY operation is to take place, which may be above the bottom of a previously drilled hole below the casing shoe (not shown). When this point is reached, the tandem drill bits A, B are rotated at the proper speed without imposing any downward weight upon them. The pumps at the top of the well bore are started, to impose pressure on the drilling iiuid or mud in the drill pipe C and the bits A, B. The pressure acts on the ball 59 in the lower bit B (which may have been previously inserted in the bit), this ball functioning as a piston and causing the stem 5l and locking plate 55 to be shifted downwardly and ejected from the lower bit. Removal of the locking plate 56 frees the lower cutters I2 and their supporting members 24 from restraint and allows the compressed springs 3d to expand, shifting the arms 33 inwardly and the legs 21 and cutters l2 in an outward direction. With the removal of the latching device, circulating fluid can pass outwardly through the lower nozzle portion 31a of the lower mandrel 3l, in order to wash the cuttings from the well bore and circulate them around the drill pipe C to the top of the hole.

Rotation of the bit assembly continues, without imposing drilling weight on the apparatus, until the lower cutters I2 form a shoulder E in the well bore, the cutters being expanded to their maximum extent. After this occurs, the drill string C may be shifted downwardly, which will shift the upper mandrel 60 and its tubular member 'l1 downwardly within the upper bit body I'I, the latch elements 9| being moved downwardly from the upper plugs '16, releasing the upper cutters I3 for outward expansion. However, the outer surfaces 10c of the legs 'I0 will merely move outwardly into engagement with the wall of the hole D, since such surfaces initially project slightly beyond the cutters I3. Inasmuch as the cutters I3 cannot be expanded any further, at this time, because of the confiring action of the small diameter bore hole E, continued downward movement of the drill string will then shift the entire upper bit A in a downward direction, sliding the legs 'I0 along the wall of the hole. As such downward movement occurs, the lower mandrel I4, which is rigidly secured to the upper body I1, is'moved downwardly within the lower body II to a position limited by engagement of the lower end of the kelly I8 with the lower guide washer 5d. Such downward movement of the lower mandrel positions the lower lock element 38 within and opposite the lower lugs 49, forming a positive stop or abutment precluding inward movement of the lower cutters l2 from their outwardly expanded position.

Rotation of the drill pipe C and cutters continues, the cutters I2 enlarging the hole to a greater diameter F by operating upongthe formation shoulder E. As drilling proceeds, the upper legsV 'I0 and cutters I3 will reach the enlarged hole portion F, whereupon they can expand outwardly, the cutters I3 engaging the enlarged hole wall, and then extending outwardly beyond the leg surfaces lila.

Rotation of the drill pipe C and the tool as-v semblage A, Blmay then continue, the upper spring urging the thrust member 85 dowm wardly along the mandrel '11, and, through the links 88V, urging the upper cutter supporting legs 1l) and cutters I3 in an outward direction, allowing the upper cutters to form an upper shoulder G in the well bore having an outside diameter H substantially'greater than the outside diameter F of the lower shoulder E. v The f 2,8555525 9 10 r, t spring so can .shift .the `cutters la outwardly to its body I l downwardly, and to a position` in the extent determined by engagement f tli which the look element 38is"`disposed withiniarid tnrnet block a .with tnelower'gulde s2 in the in alignment lYs/iththe lower lueel. Ezpansion upper body. Thereafter, the "imposition of 0f the upler ll'lflertl ,I3 'een then Proceed, after down Weight .on the drill pipe vC and .upper man; 5 the enlarged bore is reached, by moving'tlie drel so will ehi-ft the latter downwerulywltriin upper mandrel downwardly within the Vupper the upper body I8, untilthe lo'wer'end of the body i7 to the extent limited' by engagement of kelly 63 engages the upper 4guide and stop wash'- the lower yend of .the 'kelly v63' with the upper er 80. When such engagement'occus, the lw uide Washer Ml er end of the mandrel skirt 84'is preferably `po- 1g' In Figs'l and 2, a tandem arrangement of sitioned immediately above and closely adjacent drill bits is disclsed, 'which a le'reViOllSly the thrust block 85, to preclude any substantial drilled hole D can -b enlarged in tWO Stagesinward shifting of the cutters I3 from their If desired, llOle enlargement een take' pleCe in maximum expanded position, three or 'more stages by incorporating olle or With the lower mandrelM fully .telescoped mre eXpansible ,dri-ll bits in the assemblage. downwarmy within the lower body '1|, and with As' illustrated in Eig. 8, the' upper pin "leef a the upper mandrel v6|) fully telescoped` downlower .drill bit B iS threadedv into the lower bOdY wardly with the upper body I1, the dri-11mg box Mld of anY intermediate drill bit Ba, which weight is transmitted from the respective mar'lmay belofthesame general design aS the lower d rels directly .to their corresponding bodiesfand drill bit B. `The intermediate mandrel Ma is from such bodies to the cutter supporting mem-v threaded into the lower box I6 of an upper drill bers 2 4, 1,0 and the cutters l2, I3. The tubular bit A', whichl may bje ,of the same design as the meinbere 77, 3 1 themselves are relieved of any upper drill bit shown in. Figs. 1 and 2. The up; 0f the .drilling Weight. Rotation vof the drill bit per mandrel pin ,6| gf the upper bit is then asemblage takes place, .with the .proper @111mg 25 threadedly secured to the lower end of the drill weight imposed upon lthe sets vof cutters, the pipe C- lower cutters I2 enlarging vthe well bore to' an The. intermediate bit mandrel Ma extends intermediate diameter and the upper cutters slidabl'y into the lower box I D of its associated '3 te the desired nal diameter H, that is subbody Url, leakage around the mandrel being Sienielly greater than the intermediate diamef 3G prevented by afsutable side seal 93a` disposed in ter.v During the drilling operation, circulation va bOX glQQle .94d- Y'lllli4 intermediate. mandrel uid is pumped downwardly through the bitsv ld i5 also provided with looking elements 9m A, B, in order to flushthe cuttings .to the .top'of threaded into it and Ahauling holes 92a receiving the noletlle ball retaining plugs .32a depending from the After the hole enlargingoperatlon has been 35 intermediate bearing supporting members 24a. Completed, 0r the drill ,bits have betonte .worm The @utters l2 of the lower blt B are arranged it is merely neeeSSery lle. elevate .the drill pipel to expand outwardly to a predetermined maxl- C? Which Will reiee the upper mandrel within mum diameter in order to accomplish the first the upper body Il; and allow the upper 4cutters stage .of hole enlargement. The cutters 12a of .3 te be retracted The upper .mandrel lanee" 4o the intermediate bit Bu may be mounted on longer 66 engages the upperv retainer ring .61, toA trans supporting lees. 31a than the lower bit, so that mit the upper Pulling effort tel the upper body their Springs Illu may sluit such .cutters out-V ll Continued upward movementfthen eleyatesv Wardly to aereater .extent'than thel lower ,cutters the lower mandrel l!! Within the'lower body H, 12,399 preduee'a llole of a larger diameter K than end.- reiSeS the 190k member '3,3 apoye the sup:-L 45' that df the lower euttera The .supporting legeY inning member lugs 40, which will allow the' 1.51 ,et tile upperbita may be ,of suon length as IQW-er @utters l2 and ,their.supportine` members' to enable A@bern to be erung outwardly to a 2e to be retracted. Such latter relative eletta-t,- greater extenttnan the intermediate cutters liga, lng movement mel he eeeieifed: by lheretraotor and form a correspondingly larger diameter spring 53, although this spring ,need not beeme; 5g hole t o heele@ in the `bit atan, il desired, rnernultiplelandenl arrangement of drill bits When the drill bitaeeenlblaee erle-passes; up: illustrate Fier berlin in the Well bore Waren 'Within' the easing-"Shea thelatter with el, af @geput-,ters rurale looted iure: gages the upper-cutter"supprtiligwmmbers 19 tractd position.` n .the 'two stage bit as*-n and forces them inwardly to a retracted posi- 5:5: semplag-e,- tne pumps can be started when the ton- Similarly, the thee''eiieegesAA ill-flower location `has vbeen reached .at which the hole Geiler ,Sllplofing members ?.5 'aldf fPllC'eS' the@ enlarging .operation lato occur, to release vthe nWer'dlYtO relireleted'ljositolr'ille elllfllfe Wegner," lowerY latch from its associated cutter sup-V nsm bemg @lemmi-d m, u?? Wencafslrg: Wll-h t' Q portingY membersll, allowing the" lower springs Cutter Supp-Ortig memle 79' Mifune til? W .elA to urge the cuttersV l-zoutwardly, while the galdwu casmg lilltll me 1599 gif til-9 bitsarelbeirlgfr'otatd'to form thelower formaf. tionsho'ulder'P This' shoulder prevents theflower 'Fh-euppr S-'prmggqfm'gy-b'? pnntgd- 11u11 bodj lilifrommvingdownwardly'to any further tubular member head g3 originally lspose'l a i l 1f u jacent the thrust member' {8,5} when'the cutters 65e, GL? e ,btn- 'QI dllf .919e C.,1 [3T-*and their supporting members' 1g* are'in `e3- tlfllwreq gq-nwardly S 31 ,g the EDP?? tracted lthe'fltowelf c tv Inanrlr '60 d have' been Vexrande-d out'wa dl sliding alone tner'erm'atiee all. .tile e: per bit parte moveas e llnitin e ,devint/.arq

rection. to s hift-the-lower melidil 1l 'mediate springs 34 to urge the intermediate cutters lia outwardly.

Y Continued downward movement then slides the upper bit A and intermediate bit Ba downwardly along the formation wall D, to shift the lower mandrel I4 downwardly within the lower body II to a position in which the mandrel lock 38 is disposed within the cutter supporting lugs 4U, as determined by abutting of the lower end of the lower kelly i8 with the guide washer 54. As the rotation of the drill pipe C and bit apparatus proceeds, the proper drilling weight is imposed, to cause the lower cutters i2 to drill away the hole by operating upon its associated formation shoulder and produce the larger hole diameter P. While such drilling proceeds, the intermediate and upper cutter supporting members 24a., 'l slide along the wall of the smallest diameter hole D, the upper and intermediate cutters I3, I2a being disposed inwardly of the outermost portions of their associated cutter supports '18, 24a. The upper and intermediate drill bits A, Ba merely move downwardly as a unit, their cutters being incapable of expanding outwardly to any appreciable extent by the confining wall of the hole D. Y

As drilling by the lower cutters I2 proceeds, the intermediate cutters lZa eventually reach the enlarged well bore P produced by the lower cutters, whereupon the intermediate expansion springs 34a can operate and urge these cutters IZd outwardly and into engagement with the wall of the larger hole P. The drill pipe C and tool assemblage can then be rotated, the intermediate cutters 52a, which n-ow project outwardly beyond the outermost portions of their supporting member 2da, digging into the wall of the enlarged hole P and forming a shoulder therein of a certain predetermined diameter Q, as limited by engagement of the cutter supporting members 24a with the body shoulder 36a on the body I Ic. With this shoulder formed, the drill pipe C and upper drill bit A can be moved downwardly as a unit, the upper supporting legs 'I merely sliding along the wall of the smallest hole D. This downward movement carries the intermediate mandrel Illa downwardly with it to shift its lock member 38d within the lock lugs 4ta, thereby precluding retraction of the intermediate cutters lZa from their outwardly expanded position.

Drilling weight may be imposed on the bit assemblage, the lower cutters I2 producing the larger hole P, and the intermediate cutters I2a the hole Q of still greater diameter.

As drilling proceeds, the upper cutter supporting legs li! will move out of the small diameter hole D, allowing the spring 90, or the head 33, if a spring is not used, to engage the thrust block 85 and shift it downwardly, forcing the legs 'i6 and upper cutters I3 outwardly against the wall of the enlarged hole Q and forming an annular shoulder beyond the diameter of the enlarged hole Q. When the upper cutters I3 have been expanded outwardly to their maximum extent, the upper mandrel '50 is shifted downwardly within the upper body Il, until the lower end of the kelly t3 engages the guide element 80, whereupon drilling weight can be imposed on the cutters i3 to urge them downwardly against the formation shoulder to produce the desired maximum diameter hole R.

When all three sets of cutters have been expanded outwardly, the bit may be rotated at the desired speed, with the proper drilling weight imposed on the cutters, the hole being enlarged in step "fashion from its diameter D, through the diameters P and Q, to the final diameter'R. That is, the lower'cutters l2 perform the rst stage of hole enlarging,` the intermediate cutters I2 the second stage, and the upper cutters 3 the third stage, as the sets of cutters operate upon their respective formation shoulders and cut such shoulders progressively away in a downward direction. When the drill bit assemblage has performed its operati-on of enlarging the hole, it need merely be elevated through the well bore and casing, the cutters being retracted by the casing as their respective supporting members enter the casing shoe.

Additional expansibleV bits could be connected in tandem, if desired, within practical limits, to accomplish the desired hole enlargement in stages.

It is apparent that a tandem arrangement of drill bits has been provided, that is capable of enlarging a hole to a considerably greater diameter.,

The use of toothed types of roller cutters enables hole enlargement to a substantial extent to be accomplished in hard formations. With such tandem arrangement of drill bits, a single round trip into the well bore will su'ice for greatly enlarging the hole and along an extended length of the hole, thereby saving considerable rig time and-expense, by avoiding the necessity for making individual trips into the hole with individual expansible bits to accomplish a step-by-step increase in the well bore diameter.

With the telescopic arrangement of bits, assurance is had that each set of bit cutters is expanded and locked outwardly to its full reaming diameter, in order that each bit will perform its proper share of the drilling operation. It is simply necessary to attach the drill bits to one another, and in the desired number, each drill bit being a full and complete mechanism in and of itself. The outward expansion of the cuttersy of an upper bit is dependent upon the prior outward expansion of the cutters of a lower bit. The cutters are expanded outwardly in an upward sequence, and are locked outwardly, to prevent their inward retraction, by the telescopic movement of the tubular mandrels within their respective bodies.

The hole enlarging operation can commence off bottom in a previously drilled holes or the tandem assemblage can be used in conjunction with a central bit le for the purpose of drilling a new hole and enlarging it in stages at one and the same time. Y

The inventor claims:

1. In rotary drill bit apparatus: a lower drill bit body; a lower mandrel slidably splined to said body; a lower supporting member mounted on said body for lateral outward movement with respect to said body; a lower cutter on said member; means for expanding said member and cutter outwardly of said body; an upper bit body securedV to the upper end of said lower mandrel; an upper mandrel slidably splined to said upper body; an upper supporting member mounted on said upper body for lateral outward movement with respect to said upper body; an upper cutter on said upper supporting member; means for expanding said upper member and upper cutter outwardly of said upper body to a greater extent than said lower cutter; said upper cutter being disposed entirely inwardly of the outermost surface of said upper Ysupporting member until said u pper supporting member has been expanded partially outwardly, whereby said upper cutter isi amiante 1:3 prevented `from penetrating the l'formation `'until it has been lowered into `the enlarged Ibore-produced by the lower cutter.

2. In `rotary drill bit apparatus: a ilo-wer bit having a lower body; a lower supporting member mounted on said body .for lateral outward movement with respect 'to `said body; a lowercutteron said member; means for expanding said member and cutter outwardly of said body; an -upperibit secured to the upper end vof lsaid lower bit, said upper bit having a body; an upper supporting member mounted Aon said `upper rbit body for lateral outward movement -with respect to said upper body; an upper'cutter onsaid upper ymember; lmeans'for expanding-said-rupperfmember and upper-cutter 'outwardly -of rsaid upper body to a rgreater extent thansaid lowervcutter; said upper cutter being disposed Aentirely inwardly of the outermost surface of saidvupper supporting mem- 'ber until said upper supporting memberhas been expanded partiallyoutwardly;whereby-said upper cutteris prevented frompenetrating the Vformation until it has been'lowered into the enlarged lbore produced by thelower cutter.

3. In rotarydrill-bit apparatus: af-lowerdrill bit body; a lower-mandrel slidably spline'dtovsaid tbody; a lower-supporting-member lmounted-on said body for lateral outward movement with respect to said body; #aflowercutter'on said supporting member; -means'forexpanding said supporting Vmember and icutter outwardly of said body; meansl on said mandrel for-'preventing substantial `inward movement of said :supporting -member and cutter v`from their outward expanded-position upon downward telescopic movement of said mandrel'in said body; an upper bit body secured to the upper endof'said lower mandrol; an upper mandrelslidablysplined to'said upper body; an vupper supporting -member vmounted on said upperv body icrlateralroutward movement with respect -to f said upper 'l body; f an upper cutterY on said 'upper supporting member; means for expandingsaid upper supporting member and upperfcutter outwardlyofsaidupper 'body vto a greater 'extent than said lowervsupporting member and cuttermeansion saidupper mandrel for preventing substantial yinward movement of said `upper ASupporting member and `upper cutter from-theiroutward expanded posi- 'tion upon downward telescopic-'movement'oisaid upper mandrel :in said -`upper tbody; said upper cutter being disposed entirely inwardlyof Vthe outermostsurfaceosaidaupper supporting member until said upper supporting member has been expandedl partially outwardly, wherebyfaidjupper cutter is preventedI frompenetrating-,the formation until it has been lowered linto the enlarged bore produced by the lowercutter.

Qi. In rotary `drill bit-apparatus: a lowerdrill `bit'body; a lower ymandrelfslfidably splined'wto Asaid body; a lower supporting member mounted on 'said body for lateral outward movement with -re- 'spect-v tov said-body; alowerfcutter onY saidsupporting member;- -mea-ns -forexpanding said supporting member and cutter outwardly of said body; means on said mandrel for preventing substantial inward movement of said supporting member and cutter from their outward expanded position upon downward telescopic movement of said mandrel in said body; an upper bit body secured to the upper end of said lower mandrel; an upper mandrel slidably splinded to said upper body; an upper supporting member mounted on said upper body for lateral outward movement with respect to said upper body; an upper cutter Vori said upper .supporting member.; -meaiis for expanding said upper :supporting .member ,and vupper cutter outwardly of said upper body to a greater extent than .said ,lower supporting mem.- ber andcutter; means on saiduppermandrel for preventing substantial inward Amovementof said upper supporting lmemberand upper `cutter from their -outward `expanded vposition .upon .downward telescopic movement of .said .upper mandrel lin said ,upper body; said uupper cutter being `disposed entirely .inwardly of thel outermost surface of said upper supporting .member until said upper Asupporting member z-has been expanded partially outwardly, Ywhereby said Y.upper .cutter is -prevented from lpenetrating the formation until it has :been lowered into vthe enlargedfbore produced .bythe-lower cutterrandlock means re,- leasable lby .said upper Imandrel .upon -its .downward `telescopic movementin said upperbody "for holdingy said upper supporting member `and'uppler cutterinitially inlretracted position.

f5. In rotary drilllbitapparatus: a lowerdrill bit body; a lower frmandrel .slidably splined .to said body; a'lowersupportingmember mounted on saidv body vfor lateral outwardmovement with respect -to said body; a Alower `,cutter on said suporting .member; fmeans .for A,expanding said supporting member and cutter outwardly of said body; means on ysaidmandrel iforipreventing substantial inward movementiofsai-d supporting 'member land cutter `from, theiroutwardexpanded position upon downwardtelescopic movement `rof said mandrel in said bodyyan-upperfbit bod-yv se- -curedto the upper enclof said loWermandreI; 'an upper mandrel slidablyspl-ined `,tosaid upper body; van upper `supportingmen1ber.mounted on said upper body `forwlateral :outwardfzmovement lwith respect -to'- said upper 2body;lan :upper cutter on said upper supporting member; meansforexpending saidupper supporting member andupper cutter outwardly of said upperzbody toa greater extent than said lower supporti-ng .member and cutter; means -on .said upper-mandrel forf-preventing substantial :inward movement of 4said upper supporting.member-fand. upperA cutter from their outward expandedl -position upon.- downward `telescopic `movement of .said -upper Y mandrel in said upper body; v upperlockfmeans releasable-'by said upper mandrel; upon vits downwardltelescopic movement in said'upper body --for :holding said upper supporting vvmember and yupper cutter initially in retracted position; and lower vlock ymeans 4for releasably holdinglsaid rlower .cutter supportingmember and .lower cutter initially-iin I lretracted position, :whereb-y-saidflower.lock means is --rst released fto-aenable said` lower'supporting Lmember and llower cutter to f be expanded outwardly to providea shoulder-V-in--a-bore. hole for ,stopping downward movement .of.said1low.er Lbit body to permit downward telescopingfmovement oisaidzupper mandrel .inlsaid upper lbody toire- `lease said upperlock means.

`A6.1m rotary drillbitapparatus: .-adilower drill bit-body; a lower mandrel slidabl-y splined to said body; a lower supporting member mounted on said body for lateral outward movement with respect to said body; a lower cutter on said supporting member; means for expanding said sup-,- porting member and cutter outwardly of said body; means on said mandrel for preventing sube stantial inward movement of said supporting member and cutter from their outward expanded position upon downward telescopic movement of said mandrel in said body; an upper bit body secured to the upper end of said lower mandrel;

an upper mandrel slidably splined to said upper body; an upper supporting member mounted on said upper body for lateral outward movement with respect to said upper body; an upper cutter on said upper supporting member; means for expanding said upper supporting member and upper cutter outwardly of said upper body to a greater extent than said lower supporting member and cutter; means on said upper mandrel for preventing substantial inward movement of said upper supporting member and upper cutter from their outward expanded position upon downward telescopic movement of said upper mandrel in said upper body; lock means releasable by said upper mandrel upon its downward telescopic movement in said upper body for holding said upper supporting member and upper cutter initially in retracted position; and lock means for releasably holding said lower cutter supporting member and lower cutter initially in retracted position; said upper cutter being disposed inwardly of the outermost surface of said upper supporting member, until said upper supporting member has been expanded partially outwardly, whereby said upper cutter is prevented from penetrating the formation until it has been lowered into the enlarged bore produced by the lower cutter,

7. In rotary drill bit apparatus: a lower drill bit body; a lower mandrel slidably splined to said body; a lower supporting member mounted on said body for lateral outward movement with respect to said body; a lower cutter on said supporting member; means for expanding said supporting member and cutter outwardly of said body; means on said mandrel for preventing substantial inward movement of said supporting l member and cutter from their outward expanded position upon downward telescopic movement of :said mandrel in said body; an upper bit body secured to the upper end of said lower mandrel; an upper mandrel slidably splined to said upper bit body; an upper supporting member mounted on said upper body for lateral outward movement with respect to said upper body; an upper cutter on said upper supporting member; means for expanding said upper supporting member and upper cutter outwardly of said upper body to a greater extent than said lower supporting member and lower cutter; means on said upper mandrel for preventing substantial inward movement or said upper supporting member and upper cutter from their outward expanded position upon downward telescopic movement of said upper mandrel in said upper body; upper lock means releasable by said upper mandrel upon its downward telescopic movement in said upper body for holding said upper supporting member and upper cutter initially in retracted position; said upper and lower drill bit bodies and mandrels having intercommunicating fluid passages therein; and lower lock means releasable by fluid pumped through said passages for holding said lower cutter supporting member and lower cutter initially in retracted position, whereby said lower lock means is first released by fluid pumped through said passages to enable said lower cutter supporting member and lower cutter to be expanded outwardly to provide a shoulder in a bore hole for stopping downward movement of said lower bit body to permit downward telescoping movement of said upper mandrel in said upper body to release said upper lock means.

8. In rotary drill bit apparatus: a lower bit having a lower body; a lower supporting member mounted on said body for lateral outward movement with respect to said body; a cutter on said member; means for expanding said member and cutter outwardly of vsaid body; means for limiting the maximum outward expansion of said member and cutter; an intermediate bit secured to the upper end of said lower bit, said intermediate bit having a body; an intermediate supporting member mounted on said intermediate bit body for lateral outward movement with respect to said intermediate body; an intermediate cutter on said intermediate member; means for expanding said intermediate member and intermediate cutter outwardly of said intermediate body to a greater extent than said lower cutter; means for limiting the expansion of said intermediate member and intermediate cutter to a maximum extent in which the cutting path of said intermediate cutter extends outwardly a greater radial distance than the cutting path of the lower cutter but in which said pathsoverlap; an upper bit secured to the upper end' of said intermediate bit, said upper bit having a body; an upper supporting member mounted on said upper bit body for lateral outward movement with respect to said upper body; an upper cutter on said upper member; means for expanding said upper member and upper cutter outwardly of said upper body to a greater extent than said intermediate cutter, in which the cutting path of said upper cutter is grter than that of said intermediate cutter but overlaps the path of said intermediate cutter; said intermediate and upper cutters being disposed entirely inwardly of the outermost surfaces of their respective supporting members until said respective supporting members have been expanded partially outwardly, whereby said intermediate and lower cutters are prevented from penetrating the formation until they have been lowered into the enlarged bore produced by the lower cutter.

ARCHER W. KAMNlERER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,152,151 Decker Aug. 31, 1915 1,375,094 Humason Apr. 19, 1921 1,607,937 Aldrin vNov. 23, 1926 1,640,341 Aldrin Aug. 30, 1927 2,466,991Y Kammerer Apr. 12, 1949 2,545,037 Kammerer Mar. 13, 1951

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