US3568784A

US3568784A - Expansible rotary drill bit

Info

Publication number: US3568784A
Application number: US762110A
Authority: US
Inventors: Archer W Kammerer Jr
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1968-09-24
Filing date: 1968-09-24
Publication date: 1971-03-09
Anticipated expiration: 1988-03-09

Abstract

An expansible rotary drill bit and method of using the same, wherein the expansible cutters are hydraulically held open by a quantity of liquid in a chamber between the mandrel of the bit and the cutter supporting body, the fluid being trapped in the chamber by a sleeve which closes ports in the mandrel, the sleeve being shiftable to open the ports to allow retraction of the cutters. Tools are provided for moving the sleeve in and pulling the sleeve from the mandrel of such a bit. A method is employed that uses such a bit in an air drilling operation, including the steps of filling the chamber with a fluid after lowering the bit in a drilled hole, and pressurizing the chamber to expand the cutters, and then trapping the fluid in the chamber.

Description

United States Patent Inventor Archer W.K ammerer, Jr. 3 ,208,5 32 9/ l 965 Chenoweth 166/1 96X Fullerton,.Calif. 3,339,647 9/1967 Kammerer 175/268 1968 Primary Examinerlan A. Calvert l g B Patented Mar. 1971 Attorney ernard Krlegel Assignee Baker Oil Tools, Inc.

City of Commerce, Calif.

ABSTRACT: An expansible rotary drill bit and method of EXPANSIBLE ROTARY DRILL BIT using the same, wherein the expansible cutters are hydrauli- 18 Cl 6 Bra in Fi s. Cally held open by a quantity of liquid in a chamber between aims, w 3 g the mandrel of the bit and the cutter supporting body, the fluid US. Cl. 175/268, being trapped in the chamber by a sleeve which closes ports in 175/290 the mandrel, the sleeve being shiftable to open the ports to Int. Cl. EZlb 9/32 allow retraction of the cuttem Tools are provided for moving F leld of Search 175/267- the sleeve in and pulling the sleeve f the mandrel f such a 269, 290; 196 bit. A method is employed that uses such a bit in an air drilling 7 operation, including the steps of filling the chamber with a References Cited fluid after lowering the bit in a drilled hole, and pressurizing UNITED STATES PATENTS the chamber to expand the cutters, and then trapping the fluid 2,755,070 7/1956 Kammerer 175/267 in the chamber.

x .4 l7 3 I6 4327 30 ,1 I; I, I g a I we l EXPANSHBLE ROTARY DRILL BIT in the drilling of certain boreholes into the earth, rotary expansible drill bits have been employed which are adapted to be connected to a rotary drill string, through which drill string drilling fluid is circulated to flush cuttings from the borehole as the drilling progresses, the drill bits being so constructed that a differential pressure is caused by the flow of the drilling fluid through a restriction in the drill bit, this differential pressure serving to effect outward expansion of the cutters of the drill bit. 7

In the drilling of some earth formations which are incompetent and tend to cave in or slough off into the borehole, a casing or other liner or tubular pile may be lowered during the drilling operation as the borehole'progresses. An example of such borehole drilling operations is the provision of piles in boreholes in earth formation which is not readily susceptible to the driving of piles.

However, when a gaseous fluid is employed as the drilling fluid, the creation of sufficient differential pressure to effect the expansion of the bit cutters poses a problem. In addition, even following initial expansion of the bit cutters, it sometimes becomes necessary to retrieve the bit from the borehole by allowing the cutters to move to retracted positions so that the bit may be moved upwardly through'the pile or casing in the previously drilled borehole. On the other hand, the cutters of such bits may be allowed to move to the retracted position when additional lengths of drill string or drill pipe are being added.

The present invention provides a rotary expansible drill bit of the type having expansible cutter elements movable outwardly from retracted positions, wherein hydraulic means are provided for releasably holding the cutters in expanded positions.

More particularly, the invention. provides such a drill bit in which a cutter-supporting body and a mandrel define therebetween a chamber communicating with a'p'assage in the mandrel through lateral ports which are closable by, asleeve shiftable within the mandrel passage between a first position at which the ports are closed and a second position at which the ports are open, so as to trap a liquid in the chamber when the body and mandrel are in positions causing expansion of the cutters, and for allowing the fluid to bleed from the'chamber so as to enable movement of the bit body and mandrel to relative positions permitting retraction of the cutters.

Thus, a rotary expansible bit in accordance with the invention may be employed to drill a borehole through incompetent earth formation, while a casing or other liner or pile is lowered into the borehole as the latter progresses, so as to confine the sidewalls of the borehole against cave-in or sloughing off. However, when it is desired to remove the bit from the borehole, either following drilling of the borehole to its total depth or when it is necessary to service the bit, the sleeve may be shifted to a position allowing the cutters to be retracted so that the bit is free to pass upwardly through the casing or pile.

The invention also provides a shifting tool adapted to be run into the bit through the drill string into engagement with the sleeve when it is in its port-closing position, in order to move the sleeve to its second position at which the ports are open.

More particularly, the invention provides such a shifting tool which is also capable of moving the sleeve from the position at which the ports are open to the position at which the ports are closed, so as to trap liquid in the bit chamber to maintain the cutters expanded.

The invention also provides a pulling tool enabling removal of the sleeve entirely from the mandrel passage, following removal of the bit from the borehole, to allow service of the bit.

in addition to the foregoing, the invention provides a method of drilling boreholes into the earth employing an expansible rotary drill bit, wherein a casing or pile is lowered into the borehole above the bit and in which the bit is maintained in an expanded condition by trapped liquid in a chamber in the bit. in this connection, the invention contemplates plugging off the drilling fluid passage through the bit mandrel and filling or partially filling the drill string with a liquid, and, thereafter, applying air or other gas of fluid pres sure to the liquid in the drill string to effect expansion of the bit cutters, and, with the cutters expanded, running into the bit passage a tool capable of moving a sleeve to a position within the passage preventing the escape of liquid from the bit chamber, the plug then being removed from the bit passage to allow the resumption of circulation of drilling fluid therethrough.

This invention possesses many other advantages and has other purposes which may be made more clearly apparent from a consideration of a form and method embodying the invention. This form and method are shown and described in the present specification and in thedrawings accompanying and constituting a part thereof. They will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIG. 1 is a longitudinal section illustrating a rotary expansible drill bit in accordance with the invention, with the cutters expanded to drill a borehole in which a casing or pile is being lowered as the drilling progresses;

FIG. 2 is a view corresponding to FIG. I, but showing the cutters in a retracted condition;

FIG. 3 is a fragmentary, longitudinal section showing the bit mandrel and body in the position at which the cutters are expanded, but with a shifting tool disposed in the bit passage and the sleeve moved to a position allowing communication between the bit chamber and the passage;

FIG. 4 is a view generally corresponding to FIG. 3, but showing the shifting tool in a position engaged with the sleeve to move the same to a position closing the ports;

FIG. 5 is a fragmentary, longitudinal section illustrating the mandrel and body in a position at which the cutters are retracted, and showing a sleeve-pulling tool engaged in the sleeve preparatory to pulling the sleeve from the bit passage;

and

FIG. 6 is a view corresponding to FIG. 5, showing the sleeve pulling tool in condition for pulling the sleeve from the bit passage. I

As shown in the drawings, a rotary expansible drill bit A is secured to the lower end of a string of drill pipe B extending to the top of a borehole C, and by means of which the drill bit is lowered or elevated through a string of casing, or other liner or pile D.

The upper portion of the rotary drill bit consists of a mandrel 10 having an upper pin 11 threadedly connected to the lower end of the string of drill pipe B. This mandrel includes an upper kelly member 12 slidably engaged in the main body 13 of the drill bit. The exterior of the lower portion 14 of the kelly is noncircular in shape, being telescopically received in a companion noncircular socket 15 formed in the main bit body l3. Specifically, the kelly exterior and the socket 15 may be of hexagonal shape to enable the kelly 12 to be moved longitudinally with respect to the body 13, while still being capable of transmitting rotary motion'to the body.

The mandrel 10 has a limited range of longitudinal movement within the body, its downward movement being determined by engagement of the lower end 16 of the kelly with an inwardly directed body shoulder 17, and its relative upward movement being limited by engagement of an external shoulder or piston portion 18 of the kelly with a cylinder head 19 secured to the body. The upper end of the head has a flange 20 engaging a body shoulder 21, the head 19 being prevented from moving upwardly of the body by split snap retainer rings 22 fitting in a body groove 23 and overlying the flange 20. An annular guide 24 is releasably secured to the body 13 by a split snap ring 25 above the retainer rings.

The body 13 has a plurality of expansible parts mounted on it. These include cutler supporting members 25 pivotally mounted in one or more body slots 27 on hinge pins 28 which are suitably secured to the body to prevent their loss therefrom. Each cutter supporting member 26 depends from the hinge pin 28 and carries a rotary cutter 29 on its lower end.

The cutter supporting members 26 and the cutter structures 29 themselves tend to occupy a retracted position substantially entirely within the confines of the main body 13 of the bit. These cutter supporting members and the cutter structures are expansible outwardly to engage and drill away a borehole shoulder E, as seen in FIG. 1. To accomplish the expansion, each cutter supporting member 26 has an inclined expander surface 30 on its inner portion below the hinge pin 28, which tapers in a downward and inward direction. Each expander surface terminates in a lock surface 31 formed on a lock portion 32 of the cutter supporting member. The outward expansion is accomplished by producing relative longitudinal movement between the mandrel and the body 13, which will produce relative longitudinal movement between the cutter supporting members 26 and a tubular portion 33 of the mandrel 10. The tubular portion 33 includes a lower portion 34 slidable within an elongate guide bushing 35 mounted in a bridge 36 secured in the body and extending across the body slot or slots 27. The guide bushing 35 is disposed below the lock portions 32 of the cutter supporting members 26 and is secured in place by upper and lower contractable split retainer rings 35a, 35b disposed in grooves in the bushing and engaging the upper and lower ends of the bridge 36.

Located initially substantially above the guide bushing 35 and below the hinge pins 28 and in cutter supporting member recesses 37 is a mandrel lock and expander 38, which has outer surfaces 39 adapted to engage the expander surfaces 30 and the lock surfaces 31. The lock and expander 38 may be formed integral with the tubular member 33, the upper end of the latter being piloted within a socket 40 formed in the lower portion 14 of the kelly 12. An enlarged boss 41 on the tubular member 33 engages a downwardly facing shoulder 42 of the kelly, the tubular member being held against this shoulder by a suitable split retainer or lock ring 43 snapped into an internal groove 44 encompassing the kelly socket and engaging the lower end of the tubular member boss 41.

A gaseous drilling fluid, drilling mud, or other suitable fluid can pass down through the central passage 45 in the kelly 12 from the drill string 8 and into the central passage 46 extending completely through the tubular member 33. Leakage of fluid around the exterior of the tubular member 33 is prevented by a suitable side seal ring 47, such as a rubber or rubberlike O-ring in a peripheral groove 48 in the kelly, which engages the exterior of the boss 41.

Assuming the body of the tool to be elevated relatively along the tubular mandrel 10, as seen in FIG. 1, the inclined expander surfaces 30 of the cutter supporting members 26 will shift upwardly along the lock and expander portion 38 of the tubular member 33. During such upward shifting, the cutter supporting members 26 and the cutter structures 29 carried thereby will pivot about the hinge pins 28 and be urged in an outward direction. The upward movement of the body 13 with respect to the mandrel 10 can continue until the cutter structures 29 have been shifted outwardly to their fullest extent, as determined by engagement of stop shoulders 49 on the cutter supporting members 26, with companion shoulders 50 formed in the body on opposite sides of the body slot or slots 27. When such engagement occurs, the lower end 16 of the kelly portion 12 of the tubular mandrel will engage the body shoulder 17 and the lock and expander 38 on the tubular member 33 will be disposed behind and in engagement with the lock portions 32 of the cutter supporting members 26.

It is to be noted that the surfaces 31 of the lock portions 32 of the cutter supporting members 26 and the companion surfaces 39 on the lock and expander portion 38 of the tubular member are substantially parallel to the axis of the drill bit, when the cutters 29 are fully expanded, to prevent reactive forces on the cutter structures 29 from moving the latter inwardly. As a practical matter, it is preferred that the coengaging lock surfaces 39, 31 be inclined slightly in a downward direction toward the axis of the tool to insure release of the lock and the expander portion 38 from the cutter supporting members 26, when the latter and the cutter structures 29 are to be shifted to retracted position.

The piston or enlarged portion 18 on the drill stem 12 is received within a counterbore 51 formed in the upper portion of the body of the tool. This upper portion actually constitutes a cylinder 52 having a cylindrical wall 53 extending from a lower shoulder 54 defining the bottom of the counterbore to the cylinder head 19. A confined cylinder space or chamber 55 is formed between the piston portion 18 of the kelly, the periphery of the kelly above the piston, and the cylinder 52. A suitable packing or side seal ring 56 may be provided on the piston 18, which is adapted to slidably seal against the cylindrical wall 53 of the cylinder 52. Fluid is thereby prevented from passing in a downward direction between the piston and the cylinder. Similarly, fluid is prevented from passing in an upward direction out of the annular cylinder space 55 by an inner side seal ring'58 on the cylinder head 19 slidably and sealingly engaging the periphery of the kelly above the piston 18, and also by an outer side seal ring 60 disposed in the head 19 and sealingly engaging the cylinder wall 53.

Fluid under pressure in the string of drill pipe B and in the tubular mandrel passage 45 can be fed into or bled from the cylinder space 55 through one or more side ports 62 establishing communication between the central passage 45 through the kelly and by cylinder space. Such fluid under pressure may be developed, in the illustrative bit, by restricting the flow of fluid through the kelly 12 and its companion tubular member 33 by means of a flow control member 70 mounted in the lower portion of the mandrel. As a result of such restriction of flow, the pumping of compressed gas or drilling mud at an adequate rate through the apparatus will build up a back pressure of fluid in the passage 45, which pressure will be imposed on the fluid in the cylinder space 55, acting upon the cylinder head 19 to urge the body 13 of the tool in an upward direction with respect to the tubular mandrel 10 to secure outward expansion of the cutter supporting members 26 and cutter structures 29 to their fullest extent, as above described.

As apparently disclosed in the drawings, a pair of diametrically opposed supporting members 26 and cutter structures 29 is supplied, such devices being disposed substantially from each other. Actually, it is preferred to have a drill bit with three sets of supporting members and cutter structures spaced substantially l20 from each other, to secure a smoothly running device. The two sets of supporting member structures and slots 27 in which they are disposed are shown in the interest of simplicity of the drawings.

In the event that the use of the flow restrictor is to be relied on in some types of drilling operations to effect cutter expansion, the flow of fluid through the drill bit is greatly restricted. After full cutter expansion has occurred, a greater quantity of fluid is permitted to flow through the bit. As shown, the flow control member 70, which may be made of a suitable hard material, such as tungsten carbide, is piloted upwardly within a downwardly facing counterbore 76 in the lower end 34 of the tubular member 33 of the mandrel. Below the end of the tubular member 33, the flow control device 70 is enlarged in diameter to provide a head 77 conforming to the internal diameter of the guide bushing 35 and capable of sliding therealong. The flow control member 70 is secured to the tubular member 33, as by use of welding material 7 8.

The flow control member has a central passage 79 of a comparatively large diameter opening upwardly into the passage 46 through the tubular member of the mandrel. This central passage terminates in a lower end wall of the control member having a choke orifice 81 extending therethrough communicating with the central passage 79 and opening downwardly through the end wall into the body slots 27. Above the central orifice 31, the head of the flow control member has side ports or nozzles 82 communicating with the central passage 79 and opening through the periphery of the head 77, these side ports having areas substantially greater than the area through the central orifice 81. The side ports 82 are circumferentially spaced from one another to the same extent as the cutter supporting members 26 and are aligned with the slots 27, so that when the ports 92 of the flow control member are disposed below the guide bushing 35, the ports or nozzles can discharge fluid through the slots 27 toward the expanded cutter members 29 to cool and clean them and flush the cuttings upwardly around the drill bit A and the drill pipe B to the top of the borehole.

When the cutters 29 are in their retracted position, such as disclosed in E16. 2, the mandrel and its tubular member 33 are in an upper position with respect to the body 13 of the tool and the guide bushing 35 secured thereto, to close the side ports or nozzles 82 of the control member. As a result, all of the fluid pumped down through the drill string B and the

mandrel passage

45, 46 must pass out through the choke orifice 81 of relatively small diameter, causing a comparatively large back pressure to be built up in the fluid within the kelly 12, which pressure is transmitted to the fluid in the ports 62 and the cylinder space 55 for upward action on the cylinder head 19, to elevate the body 13 and

cutters

26, 29 with respect to the mandrel 10, the

cutter structures

26, 29 moving upwardly along the expander member 38 and shifting outwardly, as described hereinabove, at which time the ports 82 are exposed (FIG. 1).

The bit A, as thustfar described, is adapted for use with the cutters 29 positively held in the expanded condition of FIG. 1, and as the borehole drilling progresses, the casing or pile D may be lowered into the borehole, its lower end being immediately above the bit. Thus, the ports 62 leading between the cylinder space or chamber 55'and the central passage 45 in the mandrel 10 are closable by a valve sleeve 90, which is slidably disposed in the passage 45. The sleeve90 has suitable upper side seal rings 91 and lower side seal rings 92 sealingly engaged with the wall of the passage 45. Between the seal rings 91 and 92, the sleeve 90 has an imperforate central portion 93 which effectively closes the mandrel ports 62 when the sleeve is in the upper position of FIG. 1, but the sleeve being movable to a lower position, as seen in FIG. 2 when it is desired that the cutters be capable of retraction. When the. sleeve 90 is in its upper position, it may confine or trap'in the cylinder space or chamber 55 a quantity of liquid, such as oil or water, or other liquid, the mandrel 10 and body 13 of the vbit thereby being hydraulically locked in relative longitudinal positions at which the cutters 29 are expanded. However, when the sleeve 90 is moved downwardly to the lower position of FIG. 2, the ports 62 can communicate with the passage 45 in the mandrel to allow bleeding off of fluid from the chamber 55 and movement of the mandrel l0 and body 13 relatively longitudinally to the position shown in FIG. 2, at which the cutters 29 are retracted.

Latch means 95 are provided on the sleeve 90 cooperable with the mandrel 10 for releasably holding the sleeve 90 in its upper position to prevent inadvertent movement of the sleeve 91). This latch means 95 is illustrated as including an annular groove 96 in the inner wall of the mandrel 10 and having an upper, upwardly inclined surface 97 and a lower, downwardly inclined surface 98. The sleeve 99 has a number of flexible latch arms 99 integral therewith and projecting upwardly therefrom,.these arms being interconnected at their upper ends by an annular head 100 which is also integral with the arms 99. These arms 99 are provided, in the illustrative assembly, by longitudinally slotting the upper portion of the sleeve 90 at a suitable number of angularly spaced locations, as at 1191, and by reducing the thickness of the arms to render them relatively flexible. Each arm 99 has an outer latch element or lug 102 having an upper inclined face 103 and a lower inclined face 104, whereby the lugs 102 are complementally engageable in the channel 96 in the mandrel passage 45. However, the upper surface 97 of the groove 96 and the upper surface 103 of the lugs 102 can cam the fingers inwardly responsiv'e to upward movement of the sleeve from the latched position; and the lower channel surface 98 and the lower lug faces 104 can cam the fingers inwardly responsive to downward movement of the sleeve 90 from the latched position.

Referring to FIGS. 3 and 4, a tool T is illustrated for shifting the sleeve 90 downwardly from the latched position to allow opening of the chamber 55 when the cutters 29 are to be retracted, and for moving the sleeve upwardly back to the latched position when fluid is to be trapped in the chamber 55.

This tool T comprises a tool mandrel in the form of an elongated rod having a threaded upper end 111 connectable to a sinker bar 112 or other adapter, whereby the tool T may be lowered through the pipe string B into the passage 45 in the bit mandrel 10 on a string of rods or wire line (not shown). At its lower end, the tool mandrel 110 has a shoulder 113, and between the threaded end 111 and the shoulder 113, the tool mandrel 110 is provided with a reduced diameter section 114. This reduced diameter section 114 lies between an upper cylindrical section 115 and a lower cylindrical section 116 of the tool mandrel 110. Slidably disposed on the

cylindrical mandrel sections

115 and 116 and spanning the reduced diameter section 114 is an elongated member, generally denoted at 117, which provides means for engaging the valve sleeve 90 to shift the same between its upper and lower positions responsive to opposite longitudinal movement of the tool mandrel 110. More particularly, the member 117 comprises an elongated tubular body 118 having an outwardly enlarged flange or head 119 at its upper end. At a plurality of circumferentially spaced locations, the member 117 is longitudinally slotted, as at 120, to provide a number of circumferentially spaced, longitudinally extended resilient arms 121. Each of the arms 121 between its ends has an outwardly projecting lug 122, and at their lower ends the arms 121 are interconnected by a lower continuous portion 123 of the member 117. The lugs 122 on the arms 121 of the tool T project outwardly for cooperative engagement with internal lug portions 102a of the lugs 102 of the flexible arms 99.

As seen in FIG. 3, when the tool T is lowered into the passage 45 through the bit mandrel 10, the lower end of the tool mandrel 110 will pass through the valve sleeve latch means 95, as will the arms 121 of the tool member 117. When the valve sleeve 90 is in the upper position, with the lugs 102 of the latch arms 99 engaged in the annular groove 96 in the bit mandrel 10, the lugs 122 on the tool fingers 121 may freely pass through the inner lugs 102a of the latch fingers 99, the enlarged head 119 of the tool member-117 coming into abutment with the upper end portion 100 of the latch means 95, to impose a downward force on the valve sleeve 90 and move the latter downwardly to the position shown in FIG. 3. Such downward movement of the valve sleeve 90 opens the bit mandrel passages or ports 62 to allow communication between the chamber 55 and the bit mandrel passage 45. Under these circumstances, the bit body 13 is free to move downwardly relative to the bit mandrel 10, the liquid flowing from the chamber through the ports, allowing the cutter supporting members 26, as previously described, to swing inwardly and move the cutters 29 to their retracted position. The cutters will remain in the retracted position to allow the drill string B to be pulled upwardly through the casing C, if the drilling is completed, or to allow servicing of the bit.

Following removal of the bit upwardly through the casing or pile D with the bit cutters retracted, it may be desired to run the same or another bit back into the borehole through the casing or pile D, with the cutters in the retracted position. However, when the bit is disposed at the desired location in the borehole where drilling is to be resumed, it is necessary to effect reexpansion of the bit. In the event that the nature of the drilling fluid circulation system being employed or the volume of available air, in the event that air or other gas is employed as the drilling fluid, is suflicient to allow the differential pressure actuation of the bit, as previously described, the bit cutters will inherently be expanded when the circulation of drilling fluid resumes.

However, the present invention contemplates trapping within the chamber 55 of the bit assembly a quantity of liquid to maintain the bit cutters in the expanded condition even when there is insufficient drilling fluid pressure to do so, and even if the circulation of fluid ceases completely, in which event there could be no pressure in the mandrel passage 45.

Thus, as also seen in FIG. 3, a plugging device 125 may be placed in the bit passage 45 or dropped into the drill string to seat in the passage 45 when it is desired to effect expansion of the bit cutters. Under these circumstances, it will be understood that the tool T, also shown in FIG. 3, would not be present since the tool T would have been removed from the bit assembly while at the top of the borehole. This plugging device 125 includes a cylindrical lower body section 126 having suitable side seal rings 127 engaging the wall of the passage 46 in the tubular mandrel section 33. The plugging device 125 also includes an enlarged tapered portion 128 adapted to land in the throat 100a leading into the passage 46 through the boss 41 of the mandrel section 33. At its upper end, the plugging device 125 has a neck 129 provided with a head 130 adapted to be engaged by a suitable recovery tool (not shown), which can move downwardly through the drill string B and into the bit mandrel passage 45 to engage the recovery head 130 and effect upward removal of the plugging device 125.

With the plugging device in place preventing downward flow of fluid through the bit assembly, the cutters 29 may be expanded by filling the drill string B to the necessary extent with a liquid, such as water or oil, and the body of liquid in the drill string may be sufficiently pressurized as to effect expansion of the bit cutters by the application of pressure in the chamber 55 upwardly against the cylinder head 19 and downwardly against the annular piston 18 which is relatively shiftable in the cylinder 52 defining the chamber 55. After the cutters have been expanded responsive to relative longitudinal movement of the bit mandrel 10 and the bit body 13 to the positions shown in FIG. 1, the tool T, previously described as being adapted to move the valve sleeve 90 to the lower position of FIG. 3, is run into the bit passage 45 through the drill string B, the lugs 122 causing the tool arms 121 to flex inwardly into the reduced diameter region 114 of the tool mandrel 110, as the lugs 122 engage and pass below the internal lugs 102a of the latch fingers 99 of the valve sleeve 90.

Thereafter, the tool T will be moved upwardly as shown in FIG. 4, the lower cylindrical section 116 of the tool mandrel 110 moving upwardly in the arms 121 ofthe tool member 117 and behind the lugs 122 to prevent their inward deflection (FIG. 4), the shoulder 113 at the lower extremity of the tool mandrel having engaged the lower end 123 of the tool member 117. Under these circumstances, the reduced diameter section 114 of the tool mandrel 110 will have been moved upwardly so that the tool arms 121 are no longer inwardly flexible. Therefore, the external lugs 122 on the arms 121 will engage beneath the internal lugs 102a of the latch fingers 99 to effect upward movement of the valve sleeve 90 until the external lugs 102 on the latch fingers 99 arrive at the internal groove 96 within the bit mandrel 10, snapping into the groove. At this time, the sleeve 90 is in its port closing position, and is releasably held against further movement in either direction by coengagement of the latch lugs 102 with the sides 97, 98 of the groove 96. Thereupon, however, the tool T may pass upwardly from the latch means 95, since the outward movement of the inner lugs 1020 of the latch fingers 99, when the latch means is engaged in the internal groove 96, will allow upward movement of the external lugs 122 of the tool T past the lugs 102a, releasing the tool T from the latch means. Thus, since the sleeve 90 is across the ports 62 the cutters 29 will be hydraulically locked in expanded positions. Thereafter, a wire line or other recovery tool will be run in through the drill string into the bit to engage the recovery head 130 of the plugging device 125, pulling it from the bit assembly to the top ofthe hole, allowing further drilling operations to resume.

When the bit assembly is at the top ofthe borehole, and it is desired to remove the valve sleeve 90 from the bit passage 45 during servicing of the bit, as, for example, for the purpose of replacement of the side seal rings 91 and 93 on the valve sleeve itself, the bit mandrel 10 and the body 13 are shifted to the relative longitudinal positions shown in FIGS. 2 and 5, with the valve sleeve in the lower or port opening position. A sleeve pulling tool P includes a tool mandrel 200 having a threaded upper end 201 for threaded connection with a connecting rod 202, or other suitable device, for effecting longitudinal movement of the pulling tool. Intermediate its ends, the pulling tool mandrel 200 has a reduced diameter section 203. Adjacent its lower end, the mandrel 200 has an enlarged cylindrical section 204 and a further enlarged lower cylindrical section 205. Slidably disposed about the tool mandrel 200 between the further enlarged cylindrical section 205 and a shoulder 206 at the lower end of the rod 202 is a colletlike device 207 having an upper annular ring 208 provided with a plurality of downwardly extended and circumferentially spaced resilient arms 209, the lower ends of which are provided with outstanding lugs 210. When the tool P is disposed within the passage 45 of the bit mandrel 10, the upper ring 208 of the pulling device 207 engages the upper head portion 100 of the latch means 95 of the valve sleeve 90, the arms 209 ex tending downwardly to a position at which the external lugs 210 are closely adjacent to the internal lugs 102a of the latch arms 99. The normal outward projection of the lugs 210 is such that they will expand beyond the diameter of the bore through the head 100 of the latch means 99, the head 100 providing a lower shoulder 1000 projecting inwardly and adapted to be engaged by the pulling tool lugs 210 when the pulling tool P is moved upwardly, as seen in FIG. 6. The tool P is insertable through the head 100, since the lugs will flex inwardly and then expand outwardly to the position shown in FIG. 5.'The rod 202 and mandrel 200 are elevated to shift the cylindrical portions behind the lugs 210 and engage the mandrel shoulder 204a with the lower ends of the lugs 210, preventing inward shifting of the lugs, thereby coupling the tool P to the sleeve 90. Upward movement of the tool P will withdraw the sleeve 90 from the mandrel 10.

While the pulling tool P has just been described as being useful for the purpose of pulling the valve sleeve 90 from the bit assembly, while the bit assembly is at the top of the borehole, it will be understood that the sleeve may be pulled while the bit assembly is at the bottom of the borehole if it appears that such pulling of the sleeve is necessary or desirable. In this connection, it will be understood that the rod 202 of the pulling tool P may be run into the drill string on a pipe or cable and the tool engaged with the latch means 95 of the sleeve 90, as shown in FIG. 5.

In the use of the present invention, the bit assembly A is connected to a lower bit F threadedly connected to the body 13 and capable of passing through the casing D to drill the hole within the shoulder E, the upper end of the bit A then being connected to the lower end of a length of tubular drilling conduit or drill pipe B with the cutters 29 hydraulically locked in an expanded condition by trapped fluid in the chamber 55. As the drilling progresses, the casing or pile D is moved downwardly in the borehole C behind the bit. If it becomes desirable to remove the bit assembly A from the borehole, it will be necessary to allow retraction of the cutters 29 to the position shown in FIG. 2. Under these circumstances, the tool T of FIGS. 3 and 4, or any other appropriate tool capable of engaging the upper head 100 of the valve sleeve latch means 99, will be lowered through the drill pipe to engage the head 100 to force the valve sleeve downwardly from its normally latched condition, releasing the trapped fluid from the chamber 55. The drill string B is then moved upwardly, the body 13 of the bit assembly remaining stationary, the expander and lock 38 on the lower mandrel section 33 moving upwardly relative to the cutter supporting members 26 and allowing the latter to swing inwardly to retract the cutters 29. Thus, the drill string B and the bit assembly may be pulled from the casing or pile D.

If it is desired to pull the valve sleeve 90 during servicing of the bit at the top of the well, such pulling may be accomplished by the pulling tool P, as previouslyfdescribed and as shown in FIGS. and 6. I

When the newly serviced or a new bit is to be run back into the borehole to continue the drilling operation, such bit will be connected to the lower end of the drill string with the valve sleeve 9% in the lower position shown in FIG. 2, and the bit assembly run into the borehole with the cutters retracted. The plugging device 125, if not initially placed inits seat 100a, may then be dropped through the drill pipe and-onto the seat 100a of the boss 41 of the lower mandrel section 33. Liquid may then be placed in the drill string to fill the chamber 55 with fluid at sufficient pressure to effect relative upward movement of the bit body 13 along the mandrel and expansion of the cutters 2?. Thereupon, the tool T will be run into the drill string and-engaged with the latch means 95, as previously described, to move the valve sleeve 90 upwardly, thereby closing off the ports 62 and trapping the liquid in the chamber 55. Further upward movement of the tool T will effect its release from the latch means and the tool T may be recovered. Thereupon, the plugging device 125 will be recovered, allowing such liquid as remains in the drill string to flow therefrom. Drilling may then be resumed employing suitable drilling fluid, such as air or gas, to remove the cuttings from the borehole. Since the cutters are hydraulically locked intheir outward or expanded positions, it is unnecessary that the fluid circulating equipment or compressors be of such output capacity as to create sufflcient differential pressure across the flow restrictor 7b, as would otherwise be necessary to effect expansion of the cutters. If the bit is picked up off of the borehole shoulder E, the cutters 29 are prevented from retracting, being retained in their maximum outwardly expanded condition.

1. in a rotary drill bit connectable to a rotary drill string for drilling a borehole in the earth: a main body, laterally movable cutter means carried by said body, means for expanding said cutter means laterally of said body from a retracted position to an expanded position, and means for releasably retaining said cutter means in said expanded position comprising means providing a hydraulic fluid chamber and a passage leading from said chamber, and releasable means for closing said passage to prevent fluid from entering saidchamber from any source and to trap hydraulic fluid in saidcharnber to retain said cutter means in expanded position, said closing means being movable from its passage closing position.

2. In a rotary drill bit as defined in claim 1; said expanding means comprising a mandrel movable longitudinally within and relative ,'to said body, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole for effecting expansion of said cutter means, said cylinder and piston means together with said body and mandrel providing said hydraulic fluid chamber.

3. In a rotary drill bit as defined in claim 1; said expanding means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole for effecting expansion of said cutter means.

4. In a rotary drill bit connectable to a rotary drill string for drilling a borehole in the earth: a body having cutters carried thereby for expansion from a retracted position laterally outwardly to expanded positions; means for expanding said cutters, including a tubular member movable relatively longitudinally in said body; said tubular member 'having a fluid passage therethrough communicating with said drill string for the flow of drilling fluid; said body and said member having means defining a fluid chamber therebetween and having pressure responsive surfaces for holding said body and said member in relative longitudinal positions with said cutters expanded, a port communicating with said chamber, and means for closing said port to prevent fluid from entering said chamber from any source and to trap fluid in said chamber with said cutters expanded.

5. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and

-19., said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open.

6. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, and means for releasably holding said sleeve in said first position.

7. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage 'in said member, said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, means for releasably holding said sleeve in said first position, and means adapted to be disposed in said passage and engageable with said sleeve to move said sleeve from said first position to said second position.

8. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve in said first position.

9. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and

said means for trapping fluid in said chamber including asleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve having a plurality of circumferentially spaced flexible arms projecting longitudinally in said passage,

1 said member having an internal groove in said passage, and

said arms having external lugs engageable in said groove for holding said sleeve in said first position.

10. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve'in said first position, and tool means for engaging said sleeve to release said latch means and move said sleeve longitudinally in said passage.

11. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member,

. and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve in said first position, and tool means for engaging said sleeve to release said latch means and move said sleeve longitudinally in said passage to said second position.

12. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve in said first position, and tool means for engaging said sleeve to release said latch means and move said sleeve longitudinally in said passage for removal from said passage.

13. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve having a plurality of circumferentially spaced flexible arms projecting longitudinally in said passage, said member having an internal groove in said passage, and said arms having external lugs engageable in said groove for holding said sleeve in said first position, said sleeve also having internal abutment means, and tool means adapted to be disposed in said sleeve and having means engageable with said internal abutment means to release said external lugs from said groove to move said sleeve in said passage.

14. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve having a plurality of circumferentially spaced flexible arms projecting longitudinally in said passage, said member having an internal groove in said passage, and said arms having external lugs engageable in said groove for holding said sleeve in said first position, said sleeve also having abutment means, and tool means adapted to be disposed in said sleeve and having means engageable with said abutment means to release said external lugs from said groove to move said sleeve in said passage to said second position.

15. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve having a plurality of circumferentially spaced flexible arms projecting longitudinally in said passage, said member having an internal groove in said passage, and said arms having external lugs engageable in said groove for holding said sleeve in said first position, said sleeve also having internal abutment means, and tool means adapted to be disposed in said sleeve and having means engageable with said internal abutment means to release said external lugs from said groove to move said sleeve in said passage for removal from said passage.

16. In a rotary drill bit connectable to a rotary drill string for drilling a borehole in the earth: an elongated mandrel having a fluid passage therethrough, a body reciprocably disposed on said mandrel, expansible cutter means, means for moving said cutter means to expanded positions when said mandrel and said body are in one relative longitudinal position and for allowing retraction of said cutter means when said mandrel and said body are in another relative longitudinal position, and releasable hydraulic locking means for holding said mandrel and said body in said one relative longitudinal position; said hydraulic lock means including a cylinder head on said body, said body having a cylinder extending axially from said head, a piston on said mandrel reciprocable in said cylinder, port means leading between said mandrel passage and said cylinder between said cylinder head and said piston, said cylinder head and said piston moving one away from the other upon movement of said mandrel and said body to said one relative longitudinal position, and valve means for selectively closing and opening said port means, said valve means closing said port means to prevent fluid from flowing from said mandrel passage into said cylinder and from said cylinder into said mandrel passage, said valve means trapping fluid in said cylinder when said valve means closes said port means.

17. In a rotary drill bit as defined in claim 16; said valve means including a valve sleeve shiftable in said mandrel passage between a first position closing said port means and a second position opening said port means.

18. In a rotary drill bit as defined in claim 16; said valve means including a valve sleeve shiftable in said mandrel passage between a first position closing said port means and a second position opening said port means, and cooperable latch means in said mandrel and on said sleeve for releasably latching said valve sleeve in said first position.

Claims

1. In a rotary drill bit connectable to a rotary drill string for drilling a borehole in the earth: a main body, laterally movable cutter means carried by said body, means for expanding said cutter means laterally of said body from a retracted position to an expanded position, and means for releasably retaining said cutter means in said expanded position comprising means providing a hydraulic fluid chamber and a passage leading from said chamber, and releasable means for closing said passage to prevent fluid from entering said chamber from any source and to trap hydraulic fluid in said chamber to retain said cutter means in expanded position, said closing means being movable from its passage closing position.

2. In a rotary drill bit as defined in claim 1; said expanding means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole for effecting expansion of said cutter means, said cylinder and piston means together with said body and mandrel providing said hydraulic fluid chamber.

4. In a rotary drill bit connectable to a rotary drill string for drilling a borehole in the earth: a body having cutters carried thereby for expansion from a retracted position laterally outwardly to expanded positions; means for expanding said cutters, including a tubular member movable relatively longitudinally in said body; said tubular member having a fluid passage therethrough communicating with said drill string for the flow of drilling fluid; said body and said member having means defining a fluid chamber therebetween and having pressure responsive surfaces for holding said body and said member in relative longitudinal positions with said cutters expanded, a port communicating with said chamber, and means for closing said port to prevent fluid from entering said chamber from any source and to trap fluid in said chamber with said cutters expanded.

5. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open.

7. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, means for releasably holding said sleeve in said first position, and means adapted to be disposed in said passage and engageable with said sleeve to move said sleeve from said first position to said second position.

9. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve having a plurality of circumferentially spaced flexible arms projecting longitudinally in said passage, said member having an internal groove in said passage, and said arms having external lugs engageable in said groove for holding said sleeve in said first position.

10. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve in said first position, and tool means for engaging said sleeve to release said latch means and move said sleeve longitudinally in said passage.

11. In a rotary drill bit as defined in claim 4; said port leading between said chamber and said passage in said member, and said means for trapping fluid in said chamber including a sleeve shiftable in said passage between a first position at which said port is closed and a second position at which said port is open, said sleeve and said member having cooperative latch means for releasably holding said sleeve in said first position, and tool means for engaging said sleeve to release said latch means and move said sleeve longitudinally in said passage to said second position.