SE1930396A1 - Hybrid roller-mill bit and hybrid roller-drag bit - Google Patents

Abstract

A roller-mill bit for use in a wellbore includes: a body having a coupling formed at an upper end thereof and a plurality of lower legs; a plurality of roller disks, each roller disk secured to a bearing shaft of a respective leg for rotation relative thereto; a row of crushers mounted around each roller disk; and a fixed mill mounted to the bearing shafts and comprising a pad for each roller disk. Each pad is dressed with a cermet material.

Description

A composite rotary driiiing bit having side roiier gauge or reaming cutters for removing the outer portions of formation ittateriai from the hoie bottom and aiso intermediate drag cutters for removing the centrai portion of materiai from the bottom inside of the annuiar path traced 'py the side cutters, [Goes] US 5,853,055 discioses a rotary cone bit for driiiing bore hoies in earth formations whose body has a thread pin end and a dome end from which extend three iegs., A cutter cone is rotatabiy mounted to each ieg and is radiaiiy oriented about the bit's centrai axis. Each cutter cone has a gage row of cutting eierttents extendirig from the cone surface nearest the mouth and a nose row extending nearest the cones apex. A center jet for emitting fiuid or mud is iocated on the dome. The jet has a convergiitg nozzie with an exit orifice Which extends beiow a predefined horizontai piane intersected by the cones or cutting eiemertts. The exit orifice has a constartt diameter for a iength at ieast equai to its diameter for reducing the diffusion of the fiuid or mud fiow emitted. Fiuid or mud einitted from the center jet traveis substantiaiiy uninterrupted within a cyiindricai space between the cones which is not invaded by any cutting eiement. This reduced diffusion substantiaiiy uninterrupted fiuid fiow strikes the bore hoie bottom with maximum impact energy for enhanced removai of earth formation cuttings. [coolt] US 6,581,702 discioses a three-cone rock bit empioying a non-piugging center jet nozzie with a piuraiity of staggered iniet orifices ieading to side passageways to reduce bit baiiing. The nozzie defines a tapered cavity through which driiiing mud fiows and exits in streams. Streams are directed from the nozzie through a main exit aperture of sufficient size to avoid piugging and from side passageways boring through a sidewaii of the nozzie. Jetting streams promote washing of voids Within the bit and of cutting surfaces. The nozzie uses staggered iniet orifices ieading to side passageways, in conjunction with a tapering shape of a centrai bassageway to faciiitate maintenance of driiiirig mud veiocity within the centrai passageway and thus of stream veiocity to targeted regions of the driii bit. [bortåt US 7,845,435 discioses a hybrid driii bit having both roiier cones and fixed biades and a method of driiiing. The cutting eiements on the fixed biades form a continuous cutting profiie from the perimeter of the bit body to the axiai center. The roiier cone cutting eiements overiap with the fixed cutting eiements in the nose and shouider sections of the cutting profiie between the axiai center and the perimeter. The roiier cone cutting eiements crush and pre- or partiaiiy fracture formation in the confined and itighiy stressed nose and shouider sections. [boost US 8,678,11 1 discioses a hybrid earthboring bit inciuding a bit body having a centrai axis, at ieast one, preferabiy three fixed biades, debendirig downwardiy from the bit body, each fixed biade having a ieading edge, and at ieast one roiiing cutter, preferabiy three roiiing cutters, mounted for rotation on the bit body. A roiiing cutter is iocated between two fixed biades.

[0007] US 9,353,575 discioses an earth boring driii bit, the bit having a bit body having a centrai iongitudinai axis that defines an axiai center of the bit body and configured at its upper extent for connection into a driiistring; at ieast one primary fixed biade extending downwardiy from the bit body and inwardiy toward, but not proxirnate to, the centrai axis of the driii bit; at ieast one secondary fixed biade extending radiaiiy outward from proximate the centrai axis of the driii bit; a piuraiity of fixed cutting eiements Secured to the primary and secondary fixed biades; at ieast one bit ieg secured to the bit body; and a roiiing cutter mounted for rotation on the bit ieg; wherein the fixed cuttiiwg eierrients on at ieast orie fixed biade extend from the center of the bit outward toward the gage of the bit but do not inciude a gage cuttirwg region, and wherein at ieast one roiier cone cutter portion extends from substantiaiiy the driii bit's gage region inwardiy toward the center of the bit, the apex of the roiier cone cutter being proximate to the terminai end of the at ieast one secondary fixed biade, but does not extend to the center of the bit. [00081 US 2616/'0348440 discioses a driii bit inciudihg a bit body having a iongitudinai bit axis extending there through, a piuraiity of journais extending front the bit body, each _iotirnai fiaving a journai axis extendirtg frorn a base of the _iotiriwai through the iength of the journai, a roiier cone rotatabiy mounted to each of the journais, and at ieast one biade protruding from the bit body center and extending radiaiiy otitward to iess than an outer diameter of the driii bit.

SUMMARY GF THE ÜESCLÜSURE [coca] The present disciosure generaiiy reiates to a hybrid roiier-rniii bit and hybrid roiier-drag bit. in one entbodirttent, a roiier-rniii bit for use in a weiibore inciudes: a body having a coupiing formed at an upper end thereof and a piuraiity of iower iegs; a piuraiity of roiier disks, each roiier disk secured to a bearing shaft of a respective ieg for rotation reiative thereto; a row of crushers rnounted around each roiier disk; and a fixed rniii rnouhted to the bearing shafts and cornprisiifig a pad for each roiier disk.

Each pad is dressed with a cerrnet materiai.

BRÉEF DESCFEEPTEON GF THE DRAWENGS

[0910] So that the manner in which the above recited features of the present disciosure can be understood in detaii, a rnore particuiar description of the disciosure, brietiy surnrnarized above, may be had by reference to ernbodirnents, some of which are iiiustrated in the appended drawings. it is to be hoted, however, that the appended drawings iiiustrate oniy typicai embodiments of this disciosure and are therefore not to be considered iirniting of its scope, for the disciosure rnay adrnit to other equaiiy etfective embodiments. [cci-t] Figure i iiiustrates a hybrid roiier-miii bit positiohed for driiiing out a frac piug set in a weiibore, according to one ernbodiment of the present disciosure. Figures 2A- BB iiiustrate the roiier-rniii bit. Figures 4A-4C iiiustrates a cutter of a fixed rniii of the roiier~rniii bit. Figures 4D«4F iiiustrate rriounting of the cutter to a miii pad of the hybrid bit. [ootz] Figure 5 iiiustrates driiiing of a weiibore using a hybrid roiier-drag bit, according to another embodiment of the present disciosure. Figures 6 and 7A iiiustrate the roiiendrag bit. Figure 7B iiiustrates mounting of a fixed cutting structure to the roiier-drag bit.

[Gets] Figures 8 and 9A iiiustrate a second hybrid roiier-drag bit, according to another ernbodiment of the present disciosure. [ootftt Figure 9B iiiustrates a third hybrid roiier-drag bit, according to another embodiment of the present disciosure.

DETAELED ÛESCREPTEÜN [oots] Figure 1 iiiustrates a hybrid roiier-miii bit 1 positioned for driiiing out a frac piug 2 set in a vveiibore 3, according to one embodiment of the present disciosure. For a hydrauiic fracturing operation, the frac piug 2 is set against a casing or iiner string 4 to isoiate a zone (not shown) of a formation adiacent to the vveiibore 3. To set the frac piug 2, a setting tooi (not shown) and the trac piug 2 may 'oe depioyed down the casing or iiner string 4 using a wireiine (not shown). The frac piug 2 may be set by suppiying eiectricity to the setting tooi via the wireiine to activate the setting tooi. A piston of the setting tooi rnay move an outer portion of the trac piug 2 aiong a mandrei 5 of the frac piug whiie the wireiine restrains a mandrei ot the setting tooi and the piug mandrei, thereby compressing a packing eiement 8 and driving siips 6 aiong respective siip cones 7 of the frac piug. The packing eiement 8 may be radiaiiy expanded into engagement with the casing or iiner string 4 and the siips 6 may be wedged into engagement therewith.

[0916] The casing or iiner string 4 may then be perforated above the set frac piug 2 and the isoiated zone may be hydrauiicaiiy fractured by purnping a baii 9 foiiowed by fracturing tiuid (not shown) down the casing or iiner string 4. The baii 9 rnay iand in a seat of the piug mandrei 5, thereby forcing the tracturing tiuid into the zone via the perforations. Another frac piug (not shown) may then be set above the fractured zone and the casing or iiner string 4 may again be perforated above the piug for hydrauiic tracturing of another zone. This process may be repeated many times, such as greater than or equai to ten or twenty times, untii aii of the zones adjacent to the weiibore 3 have been fractured. [som After aii of the zones have been fractured, a production vaive at the weiihead may be opened to produce fiuid from the weiibore in an attempt to retrieve the baiis 9. l-iowever, this attempt often faiis. The roiier~miii bit 1 (oniy partiaiiy shown) rnay be depioyed down the casing or iiner string 4 using coiied tubing (not shown). A driiiing motor (not shown), such as a mud motor, may connect the roiiehmiii bit 1 to the coiied tubing. The roiier-miii bit 1, driiiing motor, and coiied tubing may be coiiectiveiy referred to as a miii string. fviiiiing fiuid may be purnped down the coiied tubing, thereby driving the driiiing motor to rotate the roiier-miii bit 1 and the roiier-miii bit may be advanced into engagement with the frac piug 2, thereby driiiing out the frac piug. Once driiied out, the iniii string may be advanced to driii out the next frac piug 2 untii aii of the frac piugs have been driiied out.

[Geist Aiternativeiy, the rniii string rriay inciude a string of driii pipe instead of coiied tubing with or without the driiiing motor. Aiternativeiy, the roiier-miii bit i may be empioyed to driii out other types of downhoie toois, such as packers, bridge piugs, fioat coiiars, fioat shoes, stage coiiars, guide shoes, reamer shoes, and/or casing bits.

[Geist Figures 2A-3B iiiustrate the roiier-rniii bit i. The roiier~miii bit i may inciude a body 10, a piuraiity of roiier disks i1a~c, a piuraiity of crushers 20, and a fixed miii 12. The roiier disks iia~c, crushers 20, and fixed miii i2 may form a iower cutting face of the roiier-miii bit 1. The roiier disks iia-c and crushers 20 may be iocated at an outer portion of the cutting face and the fixed miii 12 may be iocated at an inner portion of the cutting face. [cozct The body 10 may have an upper coupiing 13, a iower ieg 14a~c for each roiier disk 'i 1a~c, and a dome 15 formed between the iegs. The body iO and the roiier disks 11a-c rnay each be made from a metai or aiioy, such as steei. The body 1G may be friade by attaching three forgings together, such as by weidirwg. The iegs t4a-c may be equaiiy spaced around the body, such as three at one hundred twenty degrees. The upper coupiing 13 may be a threaded pin for connection to the driiiing motor or driii pipe. A bore may be formed through the coupiing 13 and extend to a pienum (not shown) formed adjacent to the dome 15. [coztt Each ieg 14a-c may have an upper shouider 16s, a mid shirttaii 16h, a iower bearing shaft ißb, and a ported boss 16p. The shouider 16s, shirttaii 16h, ported boss 1 Gp, and bearing shaft 1 Gb of each ieg t4a-c may be interconnected, such as by being integraiiy formed and/or weided together. Each ported boss t6p may be in fiuid cornmunication vvith the pienum via a respective port formed in the coupiirfig 13 and may have a nozzie (not shown) fastened therein for discharging the miiiing fiuid onto the respective roiier disk 11a-c. Each bearing shaft 16b may extend from the respective shirttaii 16h in a radiaiiy inciined direction toward a center of the roiier~miii bit 1. [cozzi Aiternativeiy, the roiier~miii bit 1 may inciude a fiow passage formed through the dome 15 for each roiier disk 11a~c instead of the ported bosses iii-p. Each fiow passage may be in fiuid communication vvith the pienum and may have a nozzie (not shown) fastened therein for discharging the miiiing fiuid onto the respective roiier disk 11a-c. The fiow passages may be arranged about a center of the roiier-mitt bit 1. [oozs] The fixed miii 12 may inciude a pad 12a-c for each roiier disk 'i1a-c and a piuraiity of cutters 17 mounted to the pads. Each miii pad 12a-c may have the shape of a conicai-poiyhedron inciuding a round base 2310 and a piuraiity of side faces converging toward a truncated apex. The side faces of each rniii pad 12a-c may inciude one or more mounting faces 23:11 adjacent to the apex thereof for mating with one or more compiementary mounting faces of adjacent miii pads. The miii pads t2a- c may be attached together at the mounting faces 223m, such as by weids. Each miii pad 'i2a-c may be made from a metai or aiioy, such as steei. [som] Each bearing shaft 16b and the respective roiier disk tia-c may have one or more pairs of aiigned grooves and each pair may form a race for receiving a set of roiier bearings 18. Athrustwasher19 may be disposed between an inner face of each roiier disk tia-c and the respective base 23Éo, such as being disposed in a groove formed in the base. The roiier bearirigs 18 and thrust washers 19 may support rotation of each disk 11a-c reiative to the respective ieg 14a-c and miii pad 12a-c. The roiier bearings 18 and thrust washers 19 may be iubricated by the miiiing fiuid discharged from the respective ported boss 16p. [oozs] Each miii pad 12a~c may have a receptacie formed therein and exteriding from the base. An end of a respective bearing shaft 16b may be received in the receptacie, thereby mounting the rniii pads t2a-c to the body 1G once the miii pads 12a-c have been weided together. Each roiier disk 11a-c may be secured to the respective ieg 14a~c by entrapment between the base of the respective miii pad 12a- c and the respective shirttaii 16h. Each roiier disk may have 11a-c may have a taper formed at a periphery of the inner face and each base 23b may have a compiementary iip formed at a periphery thereof.

[0926] Aiternativeiy, each ieg 14a-c may have a iubricant reservoir (not shown) formed therein and a iubricant passage (not shown) extending from the reservoir to the respective roiier bearing set. The iubricant may be retained within each ieg t4a~c by a pair of seais (not shown), such as o~rings, each seai positioned in a respective giand (not shown) formed in an inner surface of the respective roiier disk 'i fa-c. A first giand of each pair may be iocated adjacent to the shirttaii 16h and a second giand of each pair rriay be iocated adjacent to the respective thrust washer 19, thereby preventing ieakage of iubricant from the roiier bearings 18 into the weiibore 3. A pressure compensator (not shown) may be disposed in each reservoir for reguiating iubricant pressure therein. An equaiization passage may extend from each reservoir and through the dome 15 for operation of the respective pressure cornpensator to reguiate the iubricant pressure to be siightiy greater than bottomhoie pressure. in this aiternative, the thrust washers 19 may stiii be iubricated by the miiiing fiuid discharged from the respective ported boss tßp. in a variant of this aiternative, the second giand may be iocated in the inner face of each roiier disk 11a~c such that the thrust washers 19 are aiso iubricated by the iubricant. [osar] Aiternativeiy, upper and iower edges of each shirttaii 16h may be protected frorn erosion and/or abrasion by respective hardfacing with a ceramic or cermet materiai. An outer surface of each shirttaii 16h may aiso be protected from erosion and/or abrasion by protective inserts secured into sockets thereof, such as by interference fit or brazing. Each protective insert may be made from a cermet. Each roiier disk 1 'ia-c may be treated to resist erosion and/or abrasiori by case hardening, such as carburization.

[Gaza] Each roiier disk 11a-c may have a piuraiity of iands formed therein, such as a heei iand and a gage iand. A gage row of crushers 20 may be mounted around each roiier disk 11a-c at the respective gage iand. Each crusher 20 may be an insert mounted in a respective socket formed in the respective roiier disk 1ta~c by an interference fit. Each crusher 20 may be made from a cermet, such as a cemented carbide, and may have a cyiindricai or conicai portion mouhted in the respective roiier disk tfa-c and a conicai or chisei portion protrtiding from a respective tand of the respective roiier disk.

[0929] A row of heei protectors 21 may be mounted around each roiier disk 1ta~c at a respective heei iand. Each heei protector 21 may be an insert motinted in a respective socket formed ih the respective roiier disk f 1a~c by an interference fit. Each protector 21 may be made from a cermet, such as a cemented carbide, and may be cyiindricai. [ooaot Aiternativeiy. the crushers 20 and/or heei protectors 21 may be capped with poiycrystaiiine diamond (POD). Aiterriativeiy, each crusher 2G may be a hardfaced rttiiied tooth or eacii row of the crushers may inciude both iriserts and miiied teeth. [063311 Tife roiier-rniii bit 1 may further have a iunk siot 22 formed between the shirttaiis 16h of each adjacent ieg 14a~c. Each junk siot 22 may be formed into the body 'i O, such as by miiiing and/or forging. Each ported boss i6p may be iocated in a respective juhk siot 22. Each iunk siot 22 may be sized to aiiow passage of debris (not shown) created during miiiing of the frac piugs 2 into an annuius formed between the miii string and the casing or iiner string 4. [ooazi Figures 4A-4G iiiustrate typicai one of the miii cutters tï. To form the fixed miii 12,, each miii pad 12a-c may be dressed with the rniii cutters 17. The niiii cutter 17 may be a biock, such as a cubic biock, of cerrnet materiai. The cerntet rnateriai may be a cemented carbide inciuding a binder and carbide, such as cobaihtungsten carbide. The cermet materiai may be formed into the biock by sintering, such as hot pressing. [coast The miii cutter 17 may have a pair of opposite rectanguiar sides and four profiied sides connecting the rectanguiar sides. The profiied sides may each have rectangtiiar end portions iocated adiacent to the respective rectanguiar sides and profiied mid portions connecting the respective end portions. Each rectanguiar end portion may have chamfered corners adjacent to the respective rectanguiar sides.

Each profiied portion may have a pair of opposed trapezoidai portions converging from the respective end portions toward a center of the miii cutter 17. Each profiied portion may further have a fiiieted rectanguiar center portion connecting ends of the trapezoidai portions distai from the respective end portions, Each rectangtiiai' side may have a raised peripherai portion and a recessed interior portion. Tapered waiis may connect each raised peripherai portion to the respective interior portion. Each corner of the tapered waiis may be shaved.

[0934] Figures 4D~4F iiiustrate rnourtting of the miii cutter 17 to a typicai one of the miii pads 12a-c. The side faces of each miii pad t2a-c may aiso inciude one or more, such as three, working faces 23w. Each working face 23w may have a piuraiity of grooves 24 formed therein for dressing the respective miii pad t2a-c with the miii cutters 17. The grooves 24 may each be veeshaped to faciiitate a desired orientation of the miii cutters 17 therein. The desired orientation may be either the orientation iiiustrated in Figure 4E or the orientation iiiustrated in Figure 4F. [coast Each miii cutter 17 may occupy oniy a smaii fraction of a surface of the respective miii pad 12a-c such that many cutters are necessary to dress the surface, such as greater than or equai to ten, fifteen, twenty, or thirty miii cutters. The miii cutters '17 may be mounted in the respective grooves 24, such as “oy brazing. To faciiitate the brazing operation, severai miii cutters 17 may be combined in a rod (not shown) With a tinning binder which aiiows a weider (person or robot) to rapidiy braze the cutters on the surfaces. [coast Aiternativeiy, each working face 23w may be non-profiied and the cutters mounted thereto in a random orientation. Aiteriiativeiy, each miii pad 12a-c may 'oe hardfaced with a ceramic or cermet materiai instead of having the rniii cutters 17 mounted tiiereto.

[0037] iri comparison to the prior art, When using a junk miii to driii through the frac piugs 2, excessive torque is exerted on the driiiing motor causing staiiing of the motor which adverseiy affects efficiency of the operation and shortens the service iife of the motor. When using a roiier cone driii bit to driii through the frac piugs 2, the bit may require repiacemerit before aii of the frac piugs have been driiied out due to bearing faiiure. Advantageousiy, the roiier~miii bit 1 gains the advantages of the junk miii and the roiier cone driii bit whiie not sutferirtg from the drawbacks of either. The roiier disks 11a-c reduce torque white stiii providing stabiiity against the casing or iiner string 4. Attachment of the miii pads 1'ia-c together creates additionai support tor the roiier disks 11a-c, thereby reducing ioading on the roiier bearings 18 and thrust washers 19 and extending the service iifetime thereot. Additionaiiy, the fixed iniii 'i2 may be repiaced by grinding through the weids attachihg the rniii pads 11a-c together to remove the worn fixed miii, setting new rriiii pads onto the bearing shafts. and yveidirig together the new miii pads. [dose] Figure 5 iiiustrates driiiing of a weiibore 25 using a hybrid roiier-drag bit 26, according to another einbodiinent of the present disciosure. The weiibore 25 may be driiied using a driiiihg system 27. The driiiing system 27 may inciude a driiiing rig 27r,, a fiuid handiing system 27f, a biowout preventer (BOP) 27b, a driii string 28, and a controiier, such as programmabie iogic controiier (PLC) 27p. The driiiing rig 27r may inciude a derrick 29d. top drive 30, draw vvorks 31, and a fioor 29t at its iower end having an opening through which the driii string 28 extends downwardiy into the yveiibore 25 via a weiihead 32. The BOP 27b may be connected to the weiihead 32. [coast The driii string 28 may inciude a bottomhoie assembiy (BHA) 28b and a pipe string 23p. The pipe string 28p may inciude joints of driii pipe connected together, such as by threaded coupiings. The BHA 28b may be connected to the pipe string 28p, such as by threaded coupiirigs, and inciude the roiier-drag bit 26 and one or more driii coiiars 33. The BHA members 26, 33 may be interconnected, such as by threaded coupiings.

The roiier~drag bit 26 may be rotated 34r by the top drive 30 via the pipe string 28p.

[Goriot Aiternativeiy, the BHA 28b may inciude a driiiirtg motor tor rotation of the roiier-drag bit 26 instead of or in addition to the top drive 30. Aiternativeiy, the driii string may inciude coiied tubing instead of the pipe string 28p. Aiterriativeiy, the BHA 28b may further inciude a steering tooi, such as a bent sub or rotary steering tooi, and a teiemetry upiink for cornmunication with the PLC 27p. [(1041] An upper end of the pipe string 28p may be connected to a quiii of the top drive 30. The top drive 30 may inciude a motor for rotating 34r the driii string 28. The top drive motor may be eiectric or hydrauiic. A frame of the top drive 30 may be coupied to a raii (not shown) of the derrick 29d for preventing rotation of the top drive frame during rotation 34r of the driii string 28 and aiiowiitg for verticai movement of the top drive with a traveEing biock 31t of the draw works 31. The frame of the top drive 30 may be suspended from the derrick 29d by the traveiing biock 31t. The traveiing biock 31t may be stipported by wire rope 31 r woven through sheaves of the 'oEocks 31 c,t and extending to a winch 31w for reeEing thereof, thereby raising or Eowering the traveiing bEock 31t reiative to the rig fioor 29f. [00421 The vveEihead 32 rnay be ntounted on a casing string 35 which has been depioyed into the weiibore 25 and ceniented 36 therein. A tower section of the weiibore may be verticai (shown) or deviated (not shown), such as sEanted or horizontai. [(1043] The fEuid handiing system 27f may inciude a mud pump 37, a driEiing fiuid reservoir, such as a pit 38 or tank, a soiids separator, such as a shaEe shaker 39, a pressure sensor 49,, one or more fiow iines, such as a return iine 4tr, a suppiy Eine 41 s, and a feed Eine 4tf, and a stroke counter 42. A first end ot the return iine 41r may be connected to a fiow cross 43 mounted on the weiihead 32 and a second end of the return Eine may be connected to an EnEet of the shaker 39. A iower end of the suppEy iine 4ts may be connected to an outiet of the mud pump 37 and an upper end of the suppEy Eine may be connected to an iniet of the top drive 30. The pressure sensor 4D may be assembEed as part of the suppiy Eine 4'is. A first end of the feed iine 41f may be connected to an outEet of the pit 38 and a second end of the feed iine may be connected to ari iniet of the mud pump 37. [norm] The pressure sensor 4G may be in data communication with the PLC 27p and may be operabEe to monitor standpipe pressure. The stroke counter 42 may aiso be in data communication with the PLC 27p and may be operabie to monitor a fEow rate of the mud pump 12. The PLC 27p may aiso be in contrnunication with a hook ioad ceii cianiped to the wire rope 3tr, and a position sensor of the 'vvincti 3tw for monitoring depth of the BHA 28b. The PLC 27p may further be in communication with a torque sensor and tachorneter of the top drive 30. [(1045] The mud pump 37 may pump driiiing fiuid 44 from the pit 38, through the suppEy iine 41 s, and to the top drive 30. The driiiing fiuid 44 may iriciude a base iiquEd. The base EiquEd rnay be refined or syrithetic oii, water, brine, or a water/oii ernuision. 11 The driiiing fiuid 44 may further inciude soiids dissoived or suspehded in the base iiquid, such as organophiiic ciay, iignite. and/or asphait, thereby torming a inud.

[Gimo] The driiiing fiuid 44 may fiow from the suppiy Eine 41 s and into a bore of the pipe string 28p via the top drive 30. The driiiing tiuid 44 may fiow down the pipe string 28p, through a bore of the BHA 28b, and exit the roiier-drag bit 26, where the fiuid may circuiate cuttings away from the bit and return the cuttings up an annuius 45 formed between an inner surface of the casing 35 or the weiibore 25 and an outer surface of the driii string 28. The returns 46 (driiiing tiuid 44 pius cuttirtgs) may fiow up the annuius 45, to the weiihead 32, and exit the weiihead through the fiow cross 43. The returns 46 may continue through the return itne 41r and into the shaie shaker 39 and be processed thereby to remove the cuttings, thereby contpietirtg a cycie. As the driiiing fiuid 44 and returns 46 circuiate, the driii string 28 rnay be rotated 34r by the top drive 30 and iowered 34a by the traveiing biock 3it, thereby extending the weiibore 25 to a hydrocarbon-bearing formation or to a depth sufficieht for geotherrnai power gerieration. [com Figures 6 and 7A iiiustrate the roiier-drag bit 26. Figure TB iiiustrates mounting of a fixed cutting structure 47 to the roiier~drag bit 26. The roiier-drag bit 26 may inciude a body 48, a pitiraiity of roiier disks 49a~c, a piuraiity of crushers 55g,n. and the fixed cutting structure 47. The roiier disks 49a-c. crushers 55g.n, and fixed cutting structure 47 may form a iower cuttiifig face of the roiier-drag bit 26. The roiier disks 49a-c and crushers 55g,n may be iocated at an outer portion of the cutting face and the fixed cutting structure 47 may be iocated at an inner portion of the cutting face.

[0948] The body 48 may have an upper coupiing 50, a iower ieg 51 for each roiier disk 49a-c. and a dome 52 forrned between the iegs. The body 48 and the roiier disks 49a-c may each be made frotn a metai or aiioy, such as steei. The body 48 may be made by attaching three forgings together, such as by weiding. The iegs 51 may be equaiiy spaced around the body, such as three at one hundred twenty degrees. The upper coupiing 50 may be a threaded pin for connection to the driiiing motor or driii pipe. A bore may be formed through the coupiing 50 and extend to a pienum (not shown) formed adjacent to the dome 52. 12 [otmat Each ieg 51 may have an upper shouider öfs, a mid shirttaii 51 h, a iower bearing shaft 51 b, and a portad boss 51 p. The shouider 51 s, shirttaii 51 h, ported boss 51 p, and hearing shaft 51 b of each feg 51 may be ihtercoririected, such as by being integraiiy formed and/or weided together. Each ported boss 51p may be in fiuid communication with the pienum via a respective port formed in the coupiing 50 and may have a nozzie (not shown) fastened therein for discharging the driiiing fiuid 44 onto the respective roiier disk 49a«c. Each bearirig shaft 51b may extend from the respective shirttaii 51 h in a radiaiiy inciined direction toward a center of the roiier-drag bit 26. [ooäot Aiternativeiy. the roiier-drag bit 26 may inciude a fiow passage formed through the dome 52 for each roiier disk 49a-c instead of the ported bosses 51 p. Each fiow passage may be in fiuid communication with the piehum and may have a hozzie (not shown) fastened therein for discharging the miiiing fiuid onto the respective roiier disk 4-9a»c. The fiow passages may be arranged about a center of the roiier-drag bit 26. [oostt The fixed cutting structure 47 may inciude a center hub 47h. a biade 47a-c for each roiier disk 49a-c, and a piuraiity of shear cutters 53 mounted to each biade and embedded in the hub. The hub 47h and the biades 47a-c may be monoiithic and each biade may extend radiaiiy outward from the hub. Each biade 47a-c may ftave an outer face 47f formed for rnating with a cornpierriehtary inner face 49f of an adjaceht roiier disk 49a-c. The shear cutters 53 rnay be mounted, such as by brazing, in respective pockets formed aiong ieading edges of the biades 4"ía~c. The shear cutters 53 may be embedded, such as by brazihg, in respective receptacies formed in a bottom of the center hub 47h.

[0052] Additiohaiiy, the fixed cutting structure 47 may further inciude a piuraiity of backup shear cutters (not shown). The backup shear cutters may be mounted in pockets formed aiong bottoms of the biades 47a-c, such as by brazing. Each backup shear cutter may be aiigned or siightiy offset from a respective (ieading) shear cutter 53. Additionaiiy, the fixed cutting structure 47 may further inciude a piuraiity of depth- of-cut (DOG) iimiters (hot shown). The DOG iimiters may be mouhted in sockets formed in bottoms of the biades 47a-c, such as by brazing or interference fit. The 13 DOG iimiters may be buiiet shaped or ovoid and made from any of the materiais discussed above for the crushers 20. [dosa] The center hub 47h and biades 47a-c may be made from a composite hnateriai, such as a cerarnic and/or cermet powder infiitrated by a rrietaiiic binder, or may be metaiiic, such as being made from steei, and may be hardfaced. Each sheai' Cutter 53 may inciude a superhard cutting tabie, such as poiycrystaiiine diamond, attached to a hard stibstrate. such as a cermet, thereby forming a cornpact. such as a poiycrystaiiirie diamond compact (PDC). The cerrnet may be a carbide cemented by a Group ViiiB metai, such as cobait-tungsten carbide. The substrate and the cutting tabie may each be soiid and cyiindricai and a diameter of the substrate may be equai to a diameter of the cutting tabie. [ooszi] The biades 47a~c may be equaiiy spaced around the hub 47h. such as three at one hundred twehty degrees. A void may be formed between each adjacent biade 47a-c to accomrrodate the driiiing fiuid discharged from the ported bosses 5ip. A bottom of each biade 47a-c may be contoured. The contoured bottoms may be fiush or aimost fiush with iands of the roiier disks 49a-c at the outer faces 47f. The contoured bottoms may inciine toward the dome 52 aiong the biades 47a~c approaching the hub 47h and may fiatten as the bottoms reach the hub. A thickness of the biades 47a-c and the hub 47h may correspond to a diameter of the roiier disks 49a-c, such as being equai to or aimost equai to, thereby forrning a gap between a top of the fixed cutting structure 47 and the dome 52. The diameter of each roiier disk 49a~c may be equai. A width of each biade 47a-c may range between one-haif the diameter of the roiier disks 49a-c and the diameter of the roiier disks. [ooäst Each bearing shaft 51 b and the respective roiier disk 49a-c may have one or more pairs of aiigried grooves and each pair may form a race for receiving a set of roiier bearings (not shown). A thrust washer (not shown) may be disposed between each inner face 49f and the respective outer face 47f, such as being disposed in a groove (not shown) formed in the outer face. The roiier bearings and thrust washers may support rotation of each roiier disk 49a-c reiative to the respective ieg 51 and the fixed cutting structure 47. The thrust washers may be iubricated by the driiiing fiuid 44 discharged from the ported bosses 51 p. 14 [ooäßt Each ieg 51 may have a iubricant reservoir (not shown) formed therein and a iubricant passage (not shown) extending from the reservoir to the respective roiier bearing set. The iuhricant may be retained Within each feg 51 by a pair of seais (_ not shown), such as o-rings, each seai positioned in a respective giand (not shown) formed in an inner surface of the respective roiier disk 49a-c. A first giand of each pair may foe iocated adjacent to the shirttaii 51 h and a second giand of each pair may “oe iocated adjacent to the respective thrust washer, tftereby preventing ieakage of iubricant from the roiier bearirwgs into the weiibore 25. A pressure compensator (not shown) may be disposed in each reservoir for reguiating iubricant pressure therein. An equaiization passage may extend from each reservoir and through the dome 52 for operation of the respective pressure compensatorto reguiate the iubricant pressure to 'pe siightiy greater than bottomhoie pressure. [oosrt Aiternativeiy, the second giand may 'pe iocated in the inner face of each roiier disk 49a-c such that the thrust vvashers are aiso iubricated by the iubricant. [utlöst The roiier-drag bit 26 may further inciude a threaded fastener 54 for each roiier disk 49a-c and biade 47a-c for mounting the fixed cutting structure 47 to the shirttaiis 51 h. Each 'oiade 47a-c may have a receptacie formed tnerein and extending from the respective outer face 47f. Each biade 47 may aiso have a socket (not shown) formed therein and extending from an end of the respective receptacie. Each receptacie may be oversized reiative to the respective hearing shaft 51h faciiitate positioning of the fixed cutting 47 structure onto. Each shirttaii 51 h and bearing shaft 51 'o may have a 'oore formed therein for receiving a shaft of the respective threaded fastener therethrough. Each shirttaii 51h rnay have a countersunk or counterbored opening adjacent to the respective bore for receiving a head of the respective tfireaded fastener 54. Each 'oiade socket may be threaded for receiving an end of the shaft of the respective threaded fastener 54, thereby mounting the respective biade 47a~c to the respective bearing shaft 51 b and securing each roiier disk 49a-c to the respective ieg 51 by entrapment between the outer face 47f of the respective biade and the respective shirttaii 51 h. [09591 Aiternativeiy, upper and iower edges of each shirttaii 51 h may be protected from erosion and/or abrasion as discussed above for the shirttaiis 16h. [ooßot Each roiier disk 49a~c may have a piuraiity of iands formed therein, such as a heei iand, a gage iand, and an inner iand for the roiier disks 49a,b and a heei iand and a gage iand for the roiier disk 49c. A gage row of crushers 55g may be rriounted around each roiier disk 49a-c at the respective gage iand, An inner row of crushers 55n may be mounted around each roiier disk 49a,b at the respective inner iand. Each crusher 55g,n may be an insert mounted in a respective socket formed in the respective roiier disk 49a«c by an iriterference fit. Each crusher 55g,n may be made from a cermet, such as a cemented carbide, and may have a cyiindricai or conicai portion mounted in the respective roiier disk 49a~c and a conicai or chisei portion protruding from a respective iand of the respective roiier disk.

[Oost] A row of heei protectors 56 may be mounted around each roiier disk 49a-c at a respective heei iand. Each heei protector 56 may be ah insert rnourited in a respective socket formed in the respective roiier disk 49a-c by an interference fit. Each protector 55 may be made from a cermet, such as a cemented carbide, and may be cyiihdricai. [ooozt Aiternativeiy, the crushers 55g,n and/or heei protectors 56 may be capped with poiycrystaiiine diamond (PCB). Aiternativeiy, each crusher 55g,n may be a hardfaced miiied tooth or each row of the crushers may inciude both inserts and miiied teeth.

[Goos] Figures 8 and 9A iiiustrate a second hybrid roiier-drag bit 57, according to another erribodirrient of the present disciosure. The second hybrid roiier-drag bit 57 may be assembied as part of the BHA 28b instead of the hybrid roiier-drag bit 26. The second hybrid roiiendrag bit 57 may inciude a body 58, a piuraiity of roiier disks 59a,b, the crushers 55g,n, a fixed cap 60, a stem 63, and a piuraiity of the shear cutters 53. The roiier disks 59a,b, crushers 559m, fixed cap 60, and shear cutters 53 may form a iower cutting face of the second roiier-drag bit 57. The roiier disks 59a,'o and crushers 55g,n may be iocated at an outer portion of the cutting face and the fixed cap 60 and shear cutters 53 may be iocated at an inner portion of the cutting face. [eos/tt The body 58 may have the upper coupiing 50, a iower ieg 61 for each roiier disk 59a,b, and a dome 62 formed between the iegs. The body 58 and the roiier disks 59a,b may each be made from a metai or aiioy, such as steei. The body 58 may be 16 made by attaching three forgings together, such as by weiding. The iegs 61 may be equafiy spaced around the body, such as three at one hundred twenty degrees. A bore may be formed through the coupiing 50 and extend through the dome 62. The bore may be centrafiy positioned about the second hybrid roiier-drag bit 67.

[0665] Each feg 61 may have an upper shouider 61s, a mid shirttaii 61h, and a iower bearing shaft 61 b. The shoufder 61 s, shirttaii 61 h. and bearing shaft 61 b of each feg 61 may be interconnected, such as by being integraify formed and/or weided together. Each bearing shaft 61b may extehd from the respective stiirttaii 6fh in a radiaiiy inciined direction toward a center of the second hybrid roiier-drag bit 67. Each 'oearing shaft 61 b and the respective roiier disk 59a,b may have one or more pairs of aifgned grooves and each pair may form a race for recefving a set of roiier bearings 64. The roiier bearings 64 may support rotation of each roiier disk 59a,b reiatfve to the respective feg 61 and the fixed cap 60.

[Goos] Each feg 61 may have a iubricant reservoir (not shown) formed therein and a iubrfcant passage (not shown) extendfng from the reservoir to the respective roiier bearing set. The iubricant may be retained vvithin each feg 61 by a seai (not shown), such as an o-ring, positioned in a giand (not shown) formed in an inner surface of the respective roiier disk 59a,b. A pressure compensator (not shown) may be disposed in each reservoir for regufating fubricant pressure therein. An equaiization passage may extend from each reservoir and through the dome 62 for operation of the respective pressure compensator to reguiate the iubricant pressure to be siightiy greater than bottomhoie pressure.

[Oost] Each roiier disk 59a,b may be secured to the respective feg 61 by a piuraiity of bafis (not shown) received in a race formed by afigned grooves (not shown) in each roiier disk and the respective bearing shaft 61 b. The baifs may be fed to each race by a baii passage (not shown) formed in each feg 61 and retained therein by a respective baii pfug (not shown). Each baii pfug rnay be attached to the respective feg 61. such as by wefding.

[0668] The stem 63 may be made from tftick-vxfaifed pipe and a metai or aifoy, such as steei. An upper end of the stem 63 may be threaded and may be received in a threaded socket formed in the dome 62 adjacent to the bore, thereby mounting the 17 stem to the body 58. The stem 63 may extend downwardiy from the dome 62 and have a iength corresponding to a diameter of the roiier disks 59a,b., The stem 63 may have a port formed through a waii of thereof for each roiier disk 59a,b. Each port rnay discharge driiiing fiuid 44 onto the respective roiier disk 59a,b. The second hybrid roiier-drag bit 57 may further inciude a nozzie 65 for each port. Each nozzie 65 may be ntounted to the stem, such as by having a thread formed in an outer surface thereof engaged with a respective thread formed in a waii of the stem adiacent to the respective port. Each nozzie 65 may be made from an erosion resistant materiai, such äS a CBITTIGÉ. [ooßet The fixed cap 60 may be made from any of the materiais discussed above for the biades 47a-o and hub 47h. The fixed cap 6G may have a threaded socket formed in an upper portion thereof for engagement with a threaded iower end of the stem 63, thereby mounting the fixed cap onto the stem. The fixed cap 60 may have a concave bottom and the shear cutters 53 embedded, such as by brazing, in respective receptacies formed therein. [otïlot Each roiier disk 59a,,b may have a piuraiity of iands formed therein, such as a heei iand, a gage iand, and an inner tand. A gage row of the orushers 559 may be mounted around each roiier disk 49a»c at the respective gage iand. An inner row of the crushers 55n may be mounted around each roiier disk 59a,b at the respective inner iand. A row of the heei protectors 56 may be mounted around each roiier disk 59a,b at a respective heei iand. [com Figure 9B iiiustrates a third hybrid roiier-drag bit 66, according to another embodiment of the present disciosure. The third roiier-drag bit 66 may be simiiar to the second roiier-drag bit 66 except for having a biaded cap 67 instead of the fixed cap 60 and accommodating modificatiorts therefor to the stem 63 and the dorne 62. The biaded cap 67 may be made from any of the materiais discussed above fot the biades 47a-c and hub 47h. [(1072] The modified dome may have a socket formed therein adtacent to the bore for receiving an upper end of the modified stem. Once the dorne and stem sookets have been engaged, the rnodified stem may be mounted thereto by a weid (not shown). The biaded cap 67 may have a socket formed in an upper portion thereof for 18 engagement with a iower end of the modified stem. Once the cap and stern sockets have been engaged, the biaded cap 67 may be oriented and then rnounted thereto by a weid (hot shown).

[Dora] The biaded cap 67 may be made from any of the materiais discussed above for the biades 47a-c and hub 47h. The biaded cap 67 may inciude a center hub 67h, a biade 67a-c for each roiier disk 59a.b. and a piuraiity of shear cutters 53 mounfed to each biade and embedded in the hub. The hub 67h and the biades 67a-c may be monoiithic and each biade may extend radiaiiy outward from the hub. The shear cutters 53 may be rnounted, such as by brazing, in respective pockets formed aiong ieading edges of the biades 67a-c. The shear cutters 53 may be embedded, such as by brazing, in respective receptacies formed in a bottom of the center hub 67h. A bottom of each biade 67a-c may be contoured. The contoured bottoms may iriciine toward the dome 62 aiong the biades 67a-c approaching the hub 67h and may fiatten as the bottoms reach the hub. [com Additionaiiy, the biaded cap 67 may further inciude backup shear cutters and/or DOG iimiters (not shown) as discussed above for the fixed cutting structure 47.

[Girls] The biades 67a-c may be equaiiy spaced around the hub 67h, such as three at one hundred twenty degrees. The roiier disks 59a,b may be sized such that a cavity is formed between each adjacent roiier disk. The biaded cap 67 may be oriented such that each biade 67a-c extends into the respective cavity. The biades 67a-c may extend into the cavities to create an overiap in a cutting profiie of the third roiier-drag bit 66. The biades may extend to an effective diameter greater than or equai to one- third, one-haif, or tvvo~thirds a gage diameter of the third roiier-drag bit 66. A void may be formed between each adjacent biade 67a-c to accommodate roiier disks 59a,b. [odlat Aiternativeiy, the dome and the upper portion of the stem may not be modified and connected together by the threaded connection. [oorït As used herein, reference to a weiibore may be either to a cased or iined section of the weiibore or to an open-hoie section of the vveiibore.

[0078] White the foregoing is directed to embodiments of the present disciosure. other and further embodiments of the disciosure may be devised without departing 19 from the basic scope thereof, and the scope of the inventiøn is determined by the ciairns that foilovvfl SUBSTITUTE SHEET (RULE 26)

Claims (21)

Claims

1. A roiier-ihiii bit for use in a weiibore, comprising: a body having a coupiing formed at an upper end thereof and a piuraiity of tower iegs; a piuraiity of roiier disks, each roiier disk secured to a bearing shaft of a respective leg for rotation reiative thereto; a row of crushers mounted around each roiier disk; and a fixed niiii mounted to the bearing shafts and comprising a pad for each roiier disk, wherein each pad is dreseed with a cermet materiai.

2. The roiier-miii bit of ciaim i, wherein: the roiier disks, crushers, and fixed miii form a iower cutting face of the roiier- miii bit, and the roiier disks and crushers are iocated at an outer portion of the cutting face and the fixed miii is iocated at an inner portion of the cutting face.

3. The roiier-miii bit of ciaim 2, wherein: each ieg further has a shirttaii, and each bearing shaft extends from a respective shirttaii in a radiaiiy inciined direction toward a center of the roiier-rriiii bit.

4. The roiier-miii bit of ciaim t, wherein: each miii pad has a round base and a piuraiity of side faces converging toward a truncated apex, at least one of the side faces of each ihiii pad is a mounting face, and the mili pads are attached together at the mounting faces.

5. The roiier-miii bit of ciaim 4, further comprising: a set of roiier bearings dispoeed between each bearing shaft and the respective roiier disk; and a thrust washer dispoeed between each roiier disk and the respective base.SUBSTITUTE SHEET (RULE 26)

The roiier-miii bit of ciaim 5, wherein: each ieg further has a shirttaii and a ported boss, a junk siot is formed between the shirttaiis of each adjacent ieg, and each ported boss is iooated in a respective junk siot.

7. The roiier-miii bit of ciaim 6, wherein the roiier bearings and thrust washers are oonfigured to be iubricated by fiuid discharged from the ported bosses.

8. The roiier-miii bit of ciaim 5, wherein each ieg has a iubricant reservoir formed therein and a iubricant passage extending from the reservoir to the respective rofier bearing set.

9. The roiier-miii bit of ciaim 4, wherein: each rriiif pad has a reoeptacie formed therein and extending from the base, and an end of a respective bearing shaft is received in the receptaoie, thereby mounting the miii pads to the body.

10. The roiier-miii bit of ciaim 9, wherein: each feg further has a shirttaii, and each roifer disk is secured to the respective leg by entrapment between the base of the respective miii pad and the respective shirttaii.

11. The roiier-miii bit of ciaim 9, wherein each roiier disk has a taper formed at a periphery of an inner face thereof and each base has a compiementary iip formed at a periphery thereof.

12. The roiier-miii bit of ciaim i, wherein the roiier-miii bit comprises three iegs and three roiier disks.

13. The roiier-miii bit of ciaim 1, wherein the body further has a dome formed between the iegs, a bore formed through the coupiing and extending to a pienumSUBSTITUTE SHEET (RULE 26) formed adiacent to the dome, and a passage formed through the dome for each roiier disk.

1-4. The roiier-miii bit of ciaim 1, vvherein the cermet materiai is a piuraiity of cutter biocks brazed to the pad.

15. The roIier-rniii bit of ciaim 14, wherein the Cutter biocks are brazed into grooves formed in the pad at a desired orientation.

16. The roiier-miii bit of ciaim 1-4, vvherein: each Cutter biock has a pair of opposite rectanguiar sides and four profiied sides connecting the rectanguiar sides, the profiled sides each have rectanguiar end portions located adiacent to the respective rectangular sides and profiled mid portions connecting the respective end portions, and each rectanguiar side has a raised peripherai portion and a recessed interior portion.

17. A method of driiiing out a piug using the roiier-miii bit of ciaim 1, assembiing the roiier-miii bit as part of a miii string; depioying the miii string into a casing or iiner string set in the weiibore to the piug set in the casing or iiner string; and injecting miiiing fiuid through the miii string, rotating the roiier-miii bit, and engaging the roiler-miil bit With the piug, thereby driliing out the piug.

18. A roIier-driii bit for driiling a vvelibore, comprising: a body having a coupiing formed at an upper end thereof and a piuraiity of iovver iegs; a piuraiity of roiier disks, each disk secured to a bearing shaft of a respective ieg for rotation reiative thereto; a row of crushers mounted around each roiler disk; and a fixed cutting structure mounted to the bearing shafts and inciuding: a center hub;SUBSTITUTE SHEET (RULE 26) a biade for each roiier disk, and a piuraiity of shear cutters mounted to each biade.

19. The roiier-driii bit of ciaim 18, vvherein the fixed cutting structure further has a piuraiity of shear cutters embedded in the hub.

20. The roiier-driii bit of ciaim 18, vvherein: each ieg further has a shirttaii, the roiier-driii bit further comprises a threaded fastener for each roiier disk and biade, each shirttaii and bearing shaft has a bore formed therein receiving a shaft of the respective threaded fastener therethrough, each shirttaii has an opening adjacent to the respective bore receiving a head of the respective threaded fastener, and each biade has a threaded socket formed therein and receiving an end of the shaft of the respective threaded fastener, thereby mounting the respective biade to the respective bearing shaft and securing each roiier disk to the respective leg.

21. A roiier-driii bit for driiiing a weiibore, comprising: a body having a coupiing formed at an upper end thereof, a piuraiity of iovver iegs, a dome formed between the iegs, and a bore formed through the coupiing and the dome; a pluraiity of roiier disks, each disk secured to a bearing shaft of a respective ieg for rotation reiative thereto; a row of crushers mounted around each roiier disk; and a stem mounted to the dome adiacent to the bore and having a port formed through a vvaii thereof for each roiier disk; a fixed cap mounted to a iovver end of the stem; and one or more shear cutters embedded in or mounted to the fixed cap. 22 The roiier-driii bit of ciaim 21, vvherein: the fixed cap has a center hub and a biade for each roiler disk, a cavity is formed between each adjacent roiier disk, andSUBSTITUTE SHEET (RULE 26) the fixed cap is oriented such that each biade extends inte the respective cevity.