CA1292464C - Radially stabilized drill bit - Google Patents

Abstract

RADIALLY STABILIZED DRILL BIT
ABSTRACT OF THE DISCLOSURE
A stabilized drill bit has a cylindrical main body, a formation cutting face at the lower end of the body, and means by which the upper end of the bit can be connected into a drill string. A drilling fluid flow passageway extends axially through the main body and provides flow of drilling fluid to the drilling face. A plurality of hydraulic actuated stabilizing members are arranged circumferentially about the throat and within the main body. Stabilizing members have a borehole wall engaging face thereon which can be retracted flush with the outer surface of the main body, and extended away from the main body face and into con-tact with the borehole wall, thereby stabilizing the drill bit as the bit is rotated while making hole. Hydraulic means is con-nected to the stabilizing members by which the members are pro-gressively extended toward the borehole wall as the members become worn, and which normally prevents retraction of the stabilizing members so long as drilling fluid pressure is effected within the passageway. The stabilizing members are retracted when the drilling fluid is reduced to a predetermined value.

Description

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3Z'~4 BACKGROUND OF THB INVENTION
The present invention pertains to an improved drill bit for forming boreholes as in drilling oil and gas wells. More particularly, the present invention pertain6 to drill bit~ which employ and contain polycrystalline diamond cutting elementæ, and are usually referred to as "PDC" drill bits.
Many "PDC" drill bits of the prior art experience a de~
structive whipping action, or radial vibration of the drill bit which randomly occurs during rotary operation due to clearance be-10 tween the outside of the drill bit and the wall of the borehole.
rhis whipping tendency intens ifies in proportion to the hardness or toughness of the formation being drilled and in proportion to the rotational speed of the drill bit, causing impact contact be-tween the cutting elements of the drill bit and the formation lS material being drilled, which in turn results in fractured, chip-ped, or displaced cutting elements, thus dra~tically shortening the operating life of the drill bit and causing the operatin~ life to be inconsistent and unpredictable.
Another problem oten found in prior art "P~C" drill bits 20 is erosion which is caus~d by high velocity drilling ~luid acting on the cutting mountinyq oE the cutting elements, on the drill bit face, and on other components of the bit. This shortens the operating life of the drill bit.
Another problem associated with prior art "PDC"drill 25 bits is balling, plugging, or packing of cut material onto the face of the drill bit due to uneven or unbalanced fluid flow over the Eace of the drill bit which results in reduced penetration rates and inadequate and uneven cooJing of the cutting elements and thereby unpredictably diminish the resultant drilling opera-30 tion~

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Because of the above problems, "PDC" drill bi-ts have heretofore been used eoonomically only in drilling a very limi-ted range of differen-t rock and earth formations.
US Patent No. 7t2,887 issued in November, 1902 -to Wyczynski; US Patent No. 2,857,141 issued October 21, 1958 to Carpenter; and US Patent No. 3,062,303 issued in November, 1962 to Schultz, each contain radially acting stabilizing means.
However, as the respective specifications show, each o-f those are based on considerably different and less effective prin-ciples of operation than the present invention.

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SU~RY OF THE INVENTION
A stabilized drill bit having a main body of gPneral cylindrical configuration and a pin end opposed to a lower drill face. The lower drilliny face is of a particular novel configura-tion and includes cutters thereon for penetrating geological formations when the drill bit is rotated and making hole~ A throat is formed longi-tudinally through the main body for passage of drilling fluid from a drilling string, through the bit, and through the drilling face. The drilling fluid exits the bit and flows across the face in a novel manner.
A plurality of circumferentially arranged bore are formed from the outer surface of the bit into aommunication with the bit throat. ~Iydraulically actuated stabilizing members are reciprocatingly received within the bores. Each of the stabilizing mernbers have an outer face which is retracted into alignment with the outer surface of the bit, and which can be extended outwardly from the surface of the bit and into engagement with the wall of a borehole.
Hydraulic means are incorporated into the bit by which each of the stabilizing member~ are foraed to move in a direction outwardly of the main body when the hydrostatic pressure within the throat is greater than the hydro~tatic pressure measured at the face of the stabilizing members. The hydraulic means main-tains the stabilizing members in the extended configuration, and as the face of the stabilizing member is worn, the member is further extended into engagement with the borehole wall~
The hydraulic means further enables retraction of the stabilizing members respective to the borehole wall surface when the pressure drop across the face of the bit has been equalized.

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One object of the present invention is to provide a "PDC"
drill bit having a substantially increased operating lif~ with equal or greater drilling penetration ra~e ~han-prior art "PDC" drill bits and having the capability o~ drilling more predictably and economically through an extremaly wide range of diffsrent rock and earth formations.
Another object of this invention is to provide a drill bit having reduced tendency to whip, or radially vibrata, during rotary operation.
Another object of the present invention is to provide an improved drill bit having reduced tendency to ball or plug.
Another and further object of this invention is to pro-vi-le a "PDC" drill bit that is economical to manufacture.
An additional object of the invention i5 the provision lS of a rotary drill bit having retractable stabilizer member~
arranged about the circumference thereof which can be extended into engagement with the borehole wall while making hole.
Other objects and advantages o~ the present invention will be apparent upon consideration of the following specification, with reference to the accompanying drawings forming part thereof, and in which like numeral~ correspond to like parts throughout the several views of the invention.

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BRIEF DESCRIPTION OF TH~ FORMAL ~RAWIM~S
Figure 1 is a longitudinal, cross-sectional view of the invention;
Figure 2 (on the sheet containing Figures 7-12) is a bottom view of the invention of Figure l;
Figure 3 (on the sheet containing Figure 5) is a cross-sectional view taken along line 3-3 of Figure 1;
Figure 4 is a reduced, cross-sectional view taken along line 4-4 of Figure 1;
Figure 5 is a cross-sectional view taken along line 5-5 of Figure l;
Figure 6 (on the sheet containing Figures 13 and 14) is a diagrammatical, flattened, inverted, partial side view taken along line 6-6 of Figure 2 for purposes of simplifying the drawing;
Figures 7-14, respectively, are inverted, partial cross-sectional views taken along lines 7-14, respectively, of Figure 2; and Figure 15 is a diagrammatical, part cross sectional view of a drilling operation with the bit of the present invention being schematically illustrated therewith.

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DETAILED DESCRIPTION OF THE PREF~R~E~ EM~ODINENT
Referring to the figures of th~ drawings, and.in parti-cular Figure 1, the present invention comprises an improv~d drilling bit, generally indicated by the numeral 110 J The bit has a main body 21 made of a ~uitable material such as steel. The main body 21 is generally cylindrical in shape and the upper end .
thereof is threaded in a conventional manner, or is otherwise pro-vided with a known mea~s for attachment to the end of a drill pipe or "drill string"~ The maln body 21 has a'central fluid p~age or throat 22 extending from the top threaded end, along the' ce~tral axis towards the lower end or face 23. The lower marginal end of the bit can be an integral part of the bit, as seen in Figure 1, or it can be a separate member suitabl.y attached to the main body 21.
Near the face 23, the throat 22 branches into the illustrated two flow port~ 2~ which extend from the throat 22''and through the face 23. Flow restrictors 25 are installad.in each of the ports 24 and ~re retained in place by anap ring~ 26 or other suitable retainin~ means. Opposed ~low slots 27 are machined into the face 23 and into the side's of the main body 21 a~ more clear-ly seen in Figures2 and5. The slots 27 communicate with the two ports ~4, and a~ seen in Figures 1 and 2, aach slot commences at the respective ports 24 and then spirals outward in a direotion oppo-site to the normal rotational direction of the bit. The slots continue along opposite sides ~f the face 23, then ext~nd up the opposite sides of the main body 21~
In Figures 1~2, the bit has mounted thereon a plurality of commercially available polycrystalline diamond cutters such as the illustrated cutting elements 1 through 18. The cutting ele-ments 1-18 preferably are the STR~TAPAX (TM) manufacturad by The General Electric Company. Tha cutters are installad in a oonven~
tional manner, such as by mounting ~he cutter~ on a stud/ and pressing the stud into mounting holes formed in the Eaco 23. The cutting elements l-lB preferably are arranged in two opposite spiral patterns directly behind the $10w slots 27, such as illus-trated in Figure 2.
In Figure 1, the cutters 1-18 are spuriously drawn ~ide by side to show the cut~ing profile. In actual practice, the cutters 1-18 are each advantageously positioned to cut di6tinct but overlapping circular paths during the drilling operation, so that a continuous and complete cutting operation is achieved on the bottom of a borehole.
Figures 6 and 14 show extra cutters 52 which are added to the periphery of the bit to enhance the ability of the bit to malntain accuracy of the diameter of the borehole. Any number of peripheral or "gauge" cutters 52 may be added as needsd. Each of the cutters 1-18 and the gauge cutters 52 are oriented with respect to the main body 21 to engage the formation at the most optimum cutting angle and thereby provide optimum penetration rate ~ of the bit.
The present invention includes a plurality of novel radial stabilizing pistons 29 installed in complementary radial bores 30 formed through the sides and into the main body 21 of the bit 110 to intersect the throat 22. The bores 30 are symetri-cally arranged about the longitudinal axis of the bit. The pistons 29 are arranged to be positioned as near the face 23 as possible after allowing sufficient space for the other illustra-ted components therebetween. The preferred embodiment of Figures 1-4 show eight such pistons 29, however any suitable number may be employed. The pistons 29 are reciprocated by differential ~Z~2~

pressure thereacross~ with each piston 29 having a small di~meter at the inner end thereof and a large diameter at the outer end thereof. rrhe radial bores 30 have corresponding diameters respec-tive to the small end of the pistons 29 facing radially inward S towards the center axis of the main body 21 and with ~he large ends of the pistons 29 facing radially outward. The pistons 29 may be installed directly in the main body 21 as shown, ox alter-natively may be instaLled in a separate body (not shown) which i9 removably attachable to the main body 21. The pistons 29 are ln slidably sealed to the sides of the radial bores 30 bv o-rings 31, or similar means, so that a sealed variable volume chamber 32 is formed between the smaller and larger ends of each piston 29.
The chambers 32 increase in volume as the pistons 29 move radially outward and decrease in volume as the pistons 29 move radially in-ward. The inward travel of the pistons 29 is limited by the larger diameter portion of the pistons 29 abutting against the shoulder formed at the bottom of the larger diameter portion of the bore 30. The outward ~ravel of the pistons ~9 iB limited by the illustrated shoulder 33'. The pistons 29 are prevented from rota-ting in the bore 30 hy a detent formed by punch impressions 33, or other suitable means, which 01ida~1y engage grooves 28 fonmed along the side of the piston~ 29. The grooves 28 extends rom the rim of ~he outer ends o the pistons 29, inwardly along the side of the pistons 29, to a position just short o the outer o-ring seals 31, thus allowing adequate outward travel o the pistons 29, without disrupting any o the seals 31. Each piston 29 may contain one or more gro~ves 28 as needed.
The outer face of the pistons 29 are provided with wear resistant tungsten carbide buttons 36 pressed into complementary axial holes formed in the face of the pistons 29, so that the ' ' ;'-'. " "

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wear resistant button 36 is flu6h or aligned with the outer ~aCR
o the piston 29, thereby making the outer ends of th~ pistons 29 wear resistant. The pistons 29 may alternatively be made entiraly of a wear resistant material suah a~ ceramic, or may be made wear resistant by other known expedients.
In the cross-sectional illustration o~ Figure 4, a aheck valve 34 is seen to be provided with a corresponding fluid passage 35 or each chamber 32 to allow an incompressible hydraulic fluid, such as viscous oil, to enter but not leave the variable chambex 32. In the embodiment of Figures 1-4, a common cyllndrical 1uid reservoir 51 is provided to pairs of chambers 32 and to respec-tive pairs of check valves 34, with the fluid inlet ~nds of the check valves 34 being positioned within the reservoir 51. The reservoir 51 is arranged radially respective to the longitudinal central axis of the main body 21. The reservoir 51 is illustrated as being located between pairs of chambers 32 and check valves 34.
A small, concentric radial hole 46 extends radially inward into communication with the throat 22, and into communication with the respective passages 35, and provides a means by which a blocking valve assembly 45 can be actuated.
Each radial hole 46 i8 fitted with one blocking valve 45, which includes a valve element and a mating valve seat ~orme~
at one end of a sleeve 50. The blocking valve assembly 45 is arranged to selectively block or freely allow fluid flow into or out of the reservoir 51. T~e inner end o~ each blocking valve 45 is reciprocatingly sealed respective to the corresponding radial bore 46 by an o-ring 49, or similar seal means, and is arranged to unction as a piston, with the o-ring 49 positioned inward relative to the corresponding pair of passages 35. The outer end of each blocking valve 45 is reduced in diameter respective ~o t~e holes 46 , to allow fluid to pass rom the passage 35 into t~ ~ ~
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the hole 46 and vice ver~a, and includes,,an end portiol~ whiah i6 shaped to be receiveid in sealed relationship against the illustra ted valve seat of the sleeve 50. Thei inward travel of each valve 45 is limited by the illustrated shoulder; however, a snap ring or similar retainer positioned within the inner extremity of each hole ~6 can serve as an alternative. The outward travel of,ieach valve 45 is limited by the outer end thereof seating and sealing against the valve seat'of the sleeve 50. Each ~leeve 50 is ~a6ten ed and sealed in the illustrated fixed position within each cor responding hole'46, and is positioned to provide the desired con-tact with respect to the corresponding valve 45. The length and inller bore of the sleeves 50 are sized to accommodate shanks 44 of isolating caps 43 so that the shanks 44 can reciprocate freely in a guided manner within,the bore of the sleeves 50.
The isolating caps 43 are received within the bore of the reservoir 51, and are movably sealed in a reciprocating manner therein by o-rings 48, so that hydraulic ~luid contained there-within is isolated from contaminants from without. The caps 43 have the before mentioned rigidly attached shanks 44 which are radially oriented into the sleeves 50 to st3bilize the caps 43.
The shanks 44 are grooved or flattened to allow fluid to pass through the sleeve 50 into and out of the re~ervoir 51. The caps 43, with thelr shanks 44, are arranged to freely move in a stabi-lized manner as Eluid enters o'r leiaves the reservoir 51 to there-by accommodate any change ln volume. The radial travel of the caps 43 is sufficient to provide adequate fluid displacement for the corresponding chambers 32~ The outward t~avel oE the caps 43 is limited by punch impressions 47 formed on the rim of the re-servoirs 51, or by other suitable stop means.

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During assembly of the apparatus of the present inven-tion, the chambers 32, check valves 34, pa~sa~es 35, holes 46, and the reservoir 51 are all $illed with a suitable hydraulic ~luid, and all ga bubbles ~re evacuated therefrom 80 that an incompres-sible fluid is contained therein. Hydraulic fluid can be filled through resealable drilled holes located in the caps 43, or in the body 21, or the filling could be completed be~ore the C~p8 43 are installed, or vaxious other filling methods ~ight be utilized in order to achieve this desirad result.
As best seen illustrated in Figure~ l and S, each of a plurality of additional wear resistant buttons 36 are pressed flush into each of a plurality of radial holes arran~ed symmetri-cally around the outer periphery of the lower marginal end of the rnain body 21 at a location immediately above the face 23. Any other suitable means may be employed to protect the periphery of the main body 21 from undue abrasion and wear~
In Figure l, the flow r2strictors 25 are each arranged to provide optimum fluid flow restriction therethrough whil~ also providing relatively low ~luid output velocity therefrom into the flow slots 27 and onto the face 23. In the present embodiment, each of the flow restrictors 25 aomprise a plurality o commer-cially available wear re~i~tant nozzles 37 having an o.d. corres-ponding to the size of the port~ 24 so that each port 24 contains a first or uppermost nozzle, one or more intermediate no~zles, and an outlet or lowermost nozzle. In the present embodiment, the first nozzle in each port 29 is inverted or otherwise shaped to provide diffused fluid flow and has its orifice 41 sized to provide optimum fluid flow restriction. The ~ntermediate nozzles located in each port 24 are also inverted or otherwise shaped to provide diffused $1uid flow, but have their orifices sized to ," , ~, . ,, . ~.. . ., i , j ..........

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provide relatively low fluid flow restriction. ~he outlet nozzle in each port 24 i5 non-inverted or otherwise shaped to provide straightened fluid flow, and its orifice 42 is sized to provide relatively low fluid output velocity. All the nozzles 37 are sealed to the walls of the ports 24 by o-rings 38. Different quantities, shapes, and sizes of nozzles 37 may be installed in the ports 24 depending upon the kind and degree of fluid control de-sired. Also, the restrictors 25 may be of one piece, multistage construction rather than of a plurality of series connected indivi-dual nozzles. The restrictors 25 are thus arranged to simultane-ously provide both a means for developing an effectual fluid pressure drop and a means for reducing the rasultant fluid escape velocity.
In Figures 2 and 6-14, a fluid flow isolating ridge 39 ex-tends from one side of the face 23 along the trailing edge of the lS cutters 1-18 on the first side of the face 23, across the center of the face 23, then along the trailing edge of the cutters 1-18 on the second side to the opposite side of the face 23. The ridge 39 is affixed or made integrally respective to the face 23 and is the minimum thickness for achieving the neceRsary required strength.
The height of the flow isolating ridge 39 beyond the face 23 is equal to the height of the cutters 1-18 so that the ridge 39 con-tacts and practically seals against the bottom of the borehole during the drilling operation.
In Figures 2, 6-8, and 14, a plurality of fluid flow isolating ribs 40 extend concentrically along the face 23 from the trailing side of the ridge 39 along paths concentric with the main body 21 to the leading edges of the corresponding slots 27.
The ribs 40 are solidly attached to the ridge 39 and to the face 23 and are the minimum thickn~ss considered necessary for the re quired strength. The height of the ribs 40 beyond the face 23 is equal to the height of the cutters 1-18 and to the height of the ~ 13 -~z~

ridge 39 so that the ribs 40 similarly contact the bottom o~ ~he borehole during the~drilllng operation. The ribs 40 ar~ symmetri-cally located on the face 23 spaced radially from the Genter of the face 23 the maximum distance that provides adequate fluid flow S isolation. The ridge 39 and the ribs 40 are of a material~ such as steel, that can be worn away readily by rubbing against the bottom of a borehole while making hole.
As seen in Figures 1 and 3, parallel wrench flat~ 53 are machined onto opposite sides of the neck portion of the main body 21 in the conventional fashion to accommodate aonventional tools for attaching or detaching th~ bit 110 to a drill pipe 62.
In Figure lS, a borehole 60 has a drill string 62 and drill collar 64 therein with the bit 110 attached to the lower end thereof. A drilling riy 70 manipulates the drill string 62.
Drilling fluid Elows at 72 into the string and is returned through a rotating blowout preventor 74 in the usual manner.
In operation, the upper threaded end of the main body 21 is attached in the conventional manner to the lower end of a drill pipe, or drill string 62 and is then inserted in a borehole 60 and rotated in the conventional manner. The bit is forced downward a~ainst the bottom of the borehole by weight applied to the drill string in the conventional manner. As the invention is continu-ously rotated with weight applied, the ridge 39, the ribs 40, and the cutters 1-18 are all rubbed against the bottom of the bore-hole. The ridge 39 and the ribs 40 are reduced in height due to wear against the hottom of the borehole; however, the edges of the cutters 1-18 wear only slightly due to their material of con-struction. Thus~ the cutters 1-18 penetrate the bottom of the borehole and remove material therefrom as the bit is rotated with weight applied. The action of the cutters 1-18, moves the cuttings from in front of the cutters 1-18 into the slots 27. The gauge ... . . . . ..
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cutt.ers 52 remove material Erom the wall o~ the box~holo and there-by achieve the d~sired di~meter of th~ bore hole Conventional drilling fluid, supplied in ~he conventional manner from a suitable pull-p, is continuously pumped downward at 72, through the drill string 62, through the throat 22 of the present invention~ through the flow restrictors 25, through the flo~ slots 27, then back up the bore hole annulus located outside of the drill string. The cut material is carried along by the flowing drilling fluid and is thus removed at 74 from the borehole.
1() Since the pressure drop across an orifice varies appro-ximately as the square of the c~e in flow rate of a fluid ~lowi.ng through the orifice, (P=(9PM)2/KA2) then the resultant fluid volume flowing through bDth ori-fices ~1 (i.e. both restrictors 25) of the pre~ent invention will remain practically equal or balanced when appropriate total fluid :l5 volume and pressure is maintained. The orifices 41 can be sized to provide a predetermined or desired pressure drop for any given fluid flow rate. At any give fluid flow rate,the greater the pres-sure dro~ the mQre firmly equalized or balanced the flow through the restrictors 25 becomes. Also, each corresponding port 24, flow restri~tor 25, and flow slot 27 forms and provides an isolated fluid path because the ridge 39 and the ribs 4~ all contact the bottom of the borchole and thus prevent drilling fluid flowing in one slot 27 from escaping that slot except at the upper end of th~t slot. The flow of drilling Elilid through either of the slots 27 ~ill not become overbalanced or diverted and will therefore con-tinue to flow adequately through each slot 27 and thereby force out the cut material even if packing orclogging tends to occur.
~ccordingly, balli.ng or plugging i~ efEectively avoided on the face 23 of the present bit.
Due to the configuration and arrangement of the flow rc!strictors 25, the velocity of the flowing drilling fluid as it ' ~2~2~69L

leaves the restrictors 25 and enters the 910ts 27 iS kept low enough so that no apprecia~le ~luid erosion occurs on any part of ~he present bit even when a relatively high fluid flow rate and resultant pressure drop is maintained.
Drilling fluid flowing through the present bit is at a relatively elevated pressure within the throat 22 becaose of the pressure drop measured across the restrictors 25. Thereore, an outward force is exerted on the smaller end of the pistons 29, forcing the outer ends of the pistons 29 to move outward to anyone of a number of extended positions and into relatively light contact with the wall of the borehole. Also, the blocking valves 45 are forced outward so that the outer ends of the valves g5 are seated in sealed relationship agains the valve seat end of the sleeves 50, blocking any fluid flow therethrough. As the pistons 29 move out-ward, the chambers 32 expand in volume, causing a pressure differ-ential which forces the hydraulic fluid from the reservoir 51, through the check valves 34, through the passages 35 and into the chambers 32. The caps 43 move inward to accommodate the reduced volume within the reservoirs 51. The check valves 3~ prevent any reverse flow of hydraulic fluid and thus provides a hydraulic barrier within the chambers 3Z so that the pistons 29 cannot move inward from any extended position even when an extreme opposite force is exerted inwardly on the pistons 29 from the wall o~ the borehole. In like manner, as the outer ends of the pistons 29 slowly wear due to friction against the wall of the borehole, the pistons 29 continually move slowly outward and more hydraulic fluid is drawn into and retained within the chambers 32. Thus, means are provided by which the pistons 29 are continually com-pensated for wear and remain in constant contact with the wall of the borehole. Accordingly, the present invention provides means by which a drill bit is prevented from whipping or radially vibrating. . During this time, ~;~9~

the cu~ters 1-18 and the ~auge cutters 52 are positioned where they are protectea from impact damage ~nd from the prematura failure which may otherwise result therefrom.
Reduced circulation of drilling fluid reduces the pra~-sure drop across the restrictors 25, and the fluid pressure within the thro~t ~2 is therefore reduced until it b~come~ ~uali~ed with respect to the f lùid pressure on the outæide of the main body 21.
Thus~ in this condi~ion, no outward force is exerted against the pistons 29 or the blocking valves 45. Hence, the outer ends of the blocking valves 45 are no longer sealed against the valve ~eat ends of the sleeves 50 and fluid is therefore allowed to flow therethrough. Thus, in this condition, when an inward force iB
exerted on the outer ends o~ the pistons 29, hydraulic fluid 10ws freely out of the chambers 32, through the passages 35, against the outer ends of the blocking valves 45, forcing the blocking valves inward away from the valve seat of the sleeves 50, 50 the fluid flows through the sleeves 50 past the shanks 44, and intO
the reservoirq 51. At this time, the caps 43 can move outward to accommodate the added ~luid volume within the reservoirs Sl.
Therefore, the pistons 29 can be selectively allowed to retract inward by removing fluid pressure within the throat 22.
The main body 21 and the holes and passages therein, ths pistons 29, blocking valves 45, sleeves 50, and the caps 43 with shanks 44 all can be readily fabricated by conveni~nal methods, such as machining or moldlng. The cutters 1-18, o-rings 31, wear resistant buttons 36, nozzles 37, o-rings 38, and the gauge cut-ters 52 are all readily available commercial products which can be installed in the bit of the present invention. V~rious dif-ferent check valves 34 of conventional design may bQ ~ither built into the present bit or purchased separately and assembled ... . . . .

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thereinto~ Thus, the present invention can be readily and eco-nomically manufactured.
Having thus described the invention, it is to be under-stood that certain modifications in the construction and arrange-ment of the parts thereof may be made, as deemed necessary, without departing from the scope of the appended claims.

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Claims (18)

1. Claim 1. A stabilized drill bit comprising: a general ly cylindrical main body having means at an upper end thereof for attachment to a driving means; a drilling face at the lower end of said main body, drilling cutters secured to said face; a throat formed through said main body for passage of drilling fluid to said face; flow restricting means positioned in the fluid path of the bit with said flow restricting means arranged to provide a fluid pressure drop therethrough; radially active stabilizing means for radially stabilizing said main body; means responsive to fluid pressure in said bit for applying outward force on said radi-ally active stabilizing means and thereby moving said radially active stabilizing means into any one of a range of different ex-tended positions; and blocking means for selectively preventing inward radial movement of said radially active stabilizing means from any of said extended positions upon application of radial force upon said main body opposed to said radially active stabili-zing means sufficient to displace said fluid pressure in said bit.
2. Claim 2. A stabilized drill bit as in Claim 1 wherein each of the said flow restricting means includes: a first nozzle stage shaped, sized, and arranged to provide a combination of de-sired fluid flow restriction and diffused fluid flow, an intermedi-ate nozzle stage shaped, sized, and arranged to provide a combina-tion of minimal fluid flow restriction and diffused fluid flow;
   and a final outlet nozzle stage shaped, sized, and arranged to pro vide a combination of minimal fluid flow restriction and straight-ened fluid flow.
3. Claim 3. A stabilized drill bit as in Claim 1 wherein flow from said flow restricting means occurs onto said face and along distinct isolated flow paths; said isolated flow paths in-clude ridges secured to said face and of sufficient height to con-tact the bottom of a borehole during normal operation, said ridges extend across said face and effectively barricade both sides of each said isolated flow path.
4. Claim 4. A stabilized drill bit as in Claim 1 wherein said radially active stabilizing means includes a differential di-meter piston installed in said main body and arranged to be forced radially outward by fluid pressure from said throat acting on the smaller end of said differential diameter piston, with inward radial movement of said differential diameter piston being pre-vented by a hydraulic barrier formed between the smaller and larger snds of said differential diameter piston.
5. Claim 5, A stabilized drill bit as in Claim 4 wherein said blocking means includes a check valve in combination with a blocking valve, said blocking valve being arranged to be closed by fluid pressure effected thereon and opened by removal of the fluid pressure thereon, and thereby, in combination with said check valve to selectively retain or release said hydraulic barrier formed be-between the smaller and larger ends of said differential diameter piston.
6. Claim 6. A stabilized drill bit as in Claim 1 wherein an incompressible hydraulic fluid is contained and utilized within said blocking means and is sealably contained within one or more variable volume reservoirs corresponding to said radially active stabilizing means, said variable volume reservoirs being arranged separate from contaminants without.
7. Claim 7. A stabilized drill bit as in Claim 1 wherein said flow restricting means include means for reducing the resul-tant fluid escape velocity therethrough.
8. Claim 8. A stabilized drill bit comprising; a main body having means at an upper end thereof for attachment to a driving means; means forming a drilling face at the lower end of said mail body, drilling cutters secured to said face; a throat formed through said main body for passage of drilling fluid to said face; flow re-stricting means positioned within said throat by which the fluid pressure in said throat provides a desired pressure drop there-through while simultaneously providing fluid pressure onto said face; radial stabilizing means for radially stabilizing said main body, including at least one radially acting member arranged within said main body for outward radial movement thereof and to transmit an outward radial force against the wall of the borehole while re-sisting inward radial force with inward movement thereof blocked means responsive to fluid pressure in said throat for applying out-ward radial force upon said radially acting member and thereby moving said radially acting member into any one of a range of dif-ferent extended positions; and blocking means for blocking inward radial movement of the said radially action member in any of said extended positions when radial force sufficient to displace said fluid pressure in said throat acts upon the said main body in oppo-sition to said radial stabilizing means.
9. Claim 9 The bit of Claim 8 wherein said main body in cludes a radial bore, said radial stabilizing means includes a differential diameter piston reciprocatingly received within said bore and arranged to be forced radially outward by fluid pressure acting on the smaller end of said differential diameter piston, with inward radial movement of said differential diameter piston being prevented by said blocking means which includes a hydraulic barrier formed between the smaller and larger ends of said differ-ential idameter pistion.
10. Claim 10. The bit of Claim 9 wherein the said blocking means includes a check valve in combination with a blocking valve said blocking valve is arranged to be closed by fluid pressure thereon and opened by removal of fluid pressure thereon, and thereby, in combination with said check valve. to selectively retain or release said hydraulic barrier formed between the smal-ler and larger ends of said differential diameter piston.
11. Claim 11. The bit of Claim 10 wherein an incompressible hydraulic fluid is contained and utilized within said blocking means and is sealably contained within one or more variable volume reservoirs corresponding to said radially active stabilizing means, said variable volume reservoirs arranged to keep said in-compressible hydraulic fluid within said reservoirs separate from contaminants without.
12. Claim 12. A stabilized drill bit comprising a generally cylindrical main body having an upper end opposed to a lower end, means at said upper end by which a drill bit can be attached to a driving means, means forming a drilling face at said lower end, said drilling face includes cutters thereon for penetrating geological formations when the drill bit is making hole;
    a throat formed longitudinally through said main body for passage of drilling fluid from said driving means to said drilling face;
    means forming a plurality of stabilizing members arranged circumferentially about the throat and within said main body, said stabilizing members have a formation engaging face at the outer end thereof which can be retracted towards said main body and extended outwardly past the peripheral surface of the main body and into engagement with a borehole wall to thereby stabilize the bit;
    hydraulic responsive means by which each of said stabi-lizing members are forced to move in a direction outwardly of said main body to any one of a range of different extended positions when the hydrostatic pressure within said throat is greater than the hydrostatic pressure at the face of the said stabilizing mem-bers, and blocking means which maintains the said stabilizing members extended in any one of the said extended positions in the event sufficient radial force to displace said hydrostatic pressure in said throat acts upon the said bit opposed to said stabilizing members.
13. Claim 13. The stabilized drill bit of Claim 12 wherein said hydraulic responsive means allows the stabilizing members to retract when the said hydrostatic pressure differential is re-versed or removed.
14. Claim 14. The stabilized bit of Claim 12 wherein each of the said flow restricting means includes; a first nozzle stage shaped, sized, and arranged to provide a combination of desired fluid flow restriction and diffused fluid flow; an intermediate nozzle stage shaped, sized, and arranged to provide a combination of minimal fluid flow restriction and diffused fluid flow; and a final outlet nozzle stage shaped, sized, and arranged to provide a combination of minimal fluid flow restriction and straightened fluid flow.
15. Claim 15. The stabilized bit of Claim 12 wherein the said flow isolating means include ridges secured to said face and of sufficient height to contact the bottom of a borehole during normal operation, said ridges extend across the said face to ef-fectively barricade both sides of each desired fliud flow path.
16. Claim 16. The stabilized bit of Claim 12 wherein said stabilizing member is in the form of a piston having opposed ends of different diameters; said blocking means includes a check valve in combination with a blocking valve; said blocking valve is ar-ranged to be closed by fluid pressure thereon and opened by remov-al of fluid pressure thereon, and thereby, in combination with said check valves, to selectively retain or release a hydraulic barrier formed between the smaller and larger ends of said piston.
17. Claim 17. The stabilized bit of Claim 12 wherein said stabilizing members includes a differential diameter piston installed in said main body and arranged to be forced radi-ally outward by fluid pressure acting on the smaller end of said differential diameter piston with inward radial movement of said differential diameter piston being prevented by a hydraulic barrier formed between the smaller and larger ends of the said differential diameter piston.
18. Claim 18. The stabilized bit of Claim 12 wherein an in-compressible hydraulic fliud is contained and utilized within said blocking means and is sealably contained within one or more vari-able volume reservoirs corresponding to said radially active stabilizing means, said variable volume reservoirs arranged to keep said incompressible hydraulic fluid within said reservoirs separate from contaminants without.