US2699921A - Expanding hole enlarger or underreamer for deep wells - Google Patents

Description

Jan. 18, 1955 M. A. GARRvlsoN EXPANDING HOLE ENLARGER OR UNDERREAMER FOR DEEP WELLS Filed NOV. '18, 1950 2 Sheets-Sheet l MAR/ON GARR/50N BK HIS HTTOP/VEKS, Hmm/5, K/ECH, F05 Taf? c3c HHAR/s 3y all H cz Jan. 18, 1955 M. A. GARRISON EXPANDING HOLE ENLARGER OR UNDERREAMER FOR DEEP WELLS 2 Sheets-Sheet 2 Filed Nov, 18, 1950 O .u RR mw N6 w. NA /N m on .A M

5y mb afro/emana Hn/PR/s, K/acH, POST /P HARP/5 Y United States Patent O EXPANDING HOLE ENLARGER OR UNDER- KRAMER FR DEEP WELLS Marion A. Garrison, South Pasadena, Calif., assignor to 'Regan Forge 8a Engineering Co., San Pedro, Calif., a corporation of California Application November 18, 1950, Serial No. 196,499

Z2 Claims. (Cl. Z55-'76) This invention relates to apparatus to be lowered upon the lower end of drill pipe for the purpose of venlarging or underreaming holes below the lower end of well casings previously introduced into the wells.

A particular object of the invention is to provide an underreaming structure having expanding cutters which may be easily actuated into projected underreaming lposition through pressure applied by the conventional application of drilling mud.

Additional objects are to provide novel, durable 4means for removably hingiug arms carrying the underreaming cutters to the body of the tool, and also to p rovide for positive and independent circulation of drilling mud to each cutter during operation.

Another object is to provide such a structure wherein underreaming cutters are carried upon arms actuable by piston means into underreaming position, the piston means serving additionally to block olf cutter pockets from which the cutters are projected when in operative position, whereby to avoid clogging of such pocket spaces during underreaming.

It is also an object of the invention to provide a construction wherein the largest possible cutters for a given size of apparatus may be used, and such an object is accomplished by corresponding enlargement of the aforesaid pockets for reception of the cutters while retracted to inoperative positions.

An incidental object is to eliminate linkages connecting plural cutter-carrying arms, each of the arms being directly actuated by a piston instead of through alinkage heretofore often employed. In a preferred form such an actuating piston is conical or frusto-conical at its operative end.

Another object of the invention is to provide for passage of circulating mud through the operating piston in such a manner as to provide pressure at one side in the fo operating cylinder to move the piston while eliminating substantial circulation inthe cylinder at-suchvside, whereby to reduce to a minimum the deposit of solids Vwhich are characteristically constituents of the drilling mud employed, and thereby practically to eliminate cutting action on the cylinder wall by such solids'either kfrom deposition or circulation thereof.

Another object is to provide means for the :application of substantial mud pressure to move the cutters'into operative positions, and to relieve a substantialfproportion of -such pressure after the cutters have reached operative positions, whereby the drop in mudpressure will notify the driller that the tool is ready for underreaming rotation. An incidental object is to rely fupon such pressure-reducing means to supply adequate amounts .of drilling mud to lubricate the cutters during reaming operations.

It is a further object of the invention to provide'means for positively returning the means, such Vas the aforesaid piston means, which project the cuttersto initial position so that the cutterstmay readily collapse when the instrument is withdrawn.

It is another object of the invention to locate the cutter-projecting means in such a position in the tool that it may be employed also to operate means in the nose of the tool for centering or piloting the lower end of the tool during rotation.

A still further object of the invention is to make it possible to vary the amount of projection of the cutter arms, and of the piloting means, this being ypossible 4in a particular construction by varying'the size of the coni- ICC cal vportion of the actuating piston for the cutter arms and of a corresponding actuating piston for the piloting means.

Other objects of the invention, as well as the -various features of construction thereof, will become apparent 'to those skilled in the art upon reference to the accompanying drawings which illustrate one embodiment thereof.

In the drawings:

Fig. 1 is a side elevation of an underreamer construction in accordance with this invention and employing piloting means in its lower end or nose portion;

Fig. 2 is a vertical section showing the parts of Fig. l in collapsed or inoperative position;

F1g. 3 is a similar vertical section showing the parts projected or expanded into operative position;

Figs. 4, 5, 6, and 7 are cross sections taken respectively on the lines 4 4, 5-S, 6-6, and 7--7 of Fig. 2;

Fig. 8 is an enlarged, fragmentary, vertical section indicated by the line 8 8 of Fig. 4 and showing the poppet valve construction employed; and

Fig. 9 is a vertical section on a reduced scale illustrating the use of a simplified nose at the lower end of the tool constructed without expanding piloting means.

Fig. 1 illustrates a well casing C positioned within a deep well having walls W, the hole-enlarging tool of this invention being in position adjacent the lower end of the casing.

The tool comprises a cylindrical body 1t) formed at its upper end with a conventional threaded tool-joint pin 11 to which is threadedly attached the lower end of a conventional drill pipe P through -which drilling mud is conventionally supplied to a mud-receiving bore 12 in the upper end of the body 10. The body 1t) is provided with a plurality of longitudinally extending pockets 14 which receive a corresponding number of pivoted arms 15 carrying at their lower ends frusto-conical toothed cutting wheels 16. Adjacent the lower ends of the arms 15 and extending therebelow is a cylinder 20 in which there is reciprocably mounted an actuating piston 22 whose upper end is in the form of a cone to provide a frusto-conical surface indicated at 23. Connections presently to be described exist between the piston 22 and a smaller piston-like expander 24 which actuatesvexpanding pilot shoes 25 carried in a terminal nose piece 26 constituting the lower end of the tool. When the piston 122 is operated, as presently to be described, the piston-'like expander 24 is simultaneously operated. The pilot shoes 25 vwhen expanded into the operative position show-n in Fig. 3, serve to center the nose or lower end of the tool ,so that the cutting wheels 16 are accurately positioned and the underreaming will be uniform.

The pivoted arms 15 are mounted upon horizontally disposed pivot pins 30 so that, when the arms 15 are actuated for underreaming purposes, they move in vertical planes. Each lpin 30 is mounted in a T-shaped mounting block 31 which fits snugly in the upper end of the 'respective elongated pocket 14. The yupper end of each block 31 is secured in the body 10 of the tool by cap screws 32, and a tongue portion 31a (Fig. 1) of each :block 31 is secured lby a third screw 32a. As best indicated in Fig. 1, the upper end of each arm 15 is bifurcated at 33 so that it lies at opposite sides vof the respective tongue 31a. With this arrangement the respective pivot pin 30 is positively retained against longitudinal displacement by the side walls of the respective pocket 14. The lower end ofeach arm 15 is bifurcated at 34 in a direction transverse to the bifurcation at its upper end to receive the respective frusto-conical wheel 16, the inner face of one of the arms of these lower bi furcations being disposed at an angle to the longitudinal axis of the respective arm to position the edges of the cutting teeth of the wheel at an appropriate cuttingangle with .respect lto the adjacent wall W of -the weill holeas indicated in Fig. 3. Such an angle ymay be -a small aeuteangle to the horizontal as common in the art. A pivot pin 35 retains each cutting wheel 16 in position between the bifurcations 34. To accommodate each entf ting wheel 16 the vlower end of its pocket `14 -is enlarged incircular formation Yas indicatedat l36, thereby cans;

ing the pockets 14 in combination with the enlargement 36 to have a keyhole configuration.

As seen in Figs. 2 and 3, the upper portion of the cylinder 20 is in communication with the circular enlargements 36 of the pockets 14. The inner, lower bifurcation 34 for each cutting wheel 16 is received within such upper portion of the cylinder 20 when the parts are in the inoperative position of Fig. 2 where all the arms of the cutter wheels 16 are withdrawn within the confines of the cylindrical body 10. The inner, lower face of each inner bifurcation 34 is rounded outward at 34a (Fig. 3) to provide a cam face adapted for engagement by the frusto-conical upper surface 23 of the piston 22, so that upward movement of the piston 22 will project all of the arms and cutter wheels 16 from the inoperative positions of Fig. 2 to the operative positions of Fig. 3. It is to be noted that, when the piston 22 is in the upper arm-projecting position of Fig. 3, it closes the passages which exist between the pockets 14 and the upper portion of the cylinder 20 when the parts are in the inoperative positions of Fig. 2. Such closing of the cylinder 20 prevents the accumulation therein of cuttings during the rotation of the tool. For the purpose of elevating the piston 22 to project the cutter wheels 16 and their arms 15, a conduit is reciprocably mounted in a reduced axial bore 41 in the body 1t), the conduit 40 having an axial passage 42 therethrough. A reduced lower portion of the conduit 40 which extends downward through the upper part of the cylinder 20 projects downward through an axial bore in the piston 22 and into an enlarged conductor bore 43 in the upper end of a conductor pipe 44 which is iixedly secured, as by threads shown, in an under portion of the piston 22. This conductor pipe 44, which thus reciprocates with the piston 22, extends downward into a chamber 45 within the nose piece 26 and thence downward between the pilot shoes 25 into a reduced cylinder 46 below the chamber 45 where it-is provided with the small piston-like expander 24 previously mentioned, which expander may be retained on the pipe 44 by any appropriate threaded nut connection 47 or the like. As shown in Figs. 2 and 3, the upper end of the nose piece 26 is reduced and secured by threads 48 in the lower end of the body 10. The upper end of the nose piece 26 binds in position a disc 50 which closes the cylinder 20 below the piston 22 and provides a seat for the lower end of a counterbalancing spring 52 whose upper end is received in a mud pocket 53 in the under side of the piston 22. The conductor pipe 44 is provided with a reduced axial bleeder passage 54 of smaller capacity than the axial passage 42 in the conduit 40 so that a back pressure may be built up within the enlarged bore 43 in the conductor pipe 44 receiving the lower end of the conduit 40. Such back pressure of mud, which is being introduced into the tool by way of the conduit 40, is transmitted into the pocket 53 and the lower portion of the cylinder 20 by way of two-Way ports 55 leading from the enlarged bore 43. Thus, upon adequate pressure development under the piston 22, it will be elevated along the conduit 40 and Will carry with it the conductor pipe 44 and the piston-like expander 24. To retain back pressure within the pocket 53, the pipe 44 is packed in the disc 50 by any appropriate packing means 56. The counter-balancing spring 52 is employed for the purpose of at least partially counterbalancing the weight of the piston 22, the conductor pipe 44 and the expander 24, as well as for cushioning initial downward movement of these parts under application of mud pressure to the mud bore 12 in the upper part of the tool 10. The axial passage 42 in the conduit 40 combined with the enlarged bore 43 and the axial bleeder passage 54 in the conductor pipe 44 constitute a through passage by Way of which the liquid mud is discharged at the lower end of the tool below the cylinder 20 and the closing disc 50 at the bottom of the cylinder. Since there are no circulating outlets from the cylinder 20, and since the only liquid movement to and from the cylinder 20 takes place by way of the two-Way ports 55, there is no continuing circulation of mud through the cylinder 20 and therefore no significant deposit of solids in the cylinder nor consequent cutting of the cylinder walls by such solids.

The upper endA of the conduit 40 carries a ported valve member which operates upon any appropriate valve seat 62 (Figs. 2, 3, and 8) carried upon ashoulder 63 at the top of a by-pass chamber 64 which is of suiiciently reduced cross section with respect'to the mud bore 12 and the valve 60 to provide for the ready passage of drilling mud or other fluid around the valve member 60 when lifted. Bleeder ports 65 (Figs. 2 and 8) in the valve member 60 provide for bleeding into the chamber 64 of a small portion of mud supplied under pressure to the mud bore 12 while the valve member 60 is closed and until such time as the valve member 6i) is lifted, whereupon the mud under pressure largely passes into the by-pass chamber 64.

The mud which enters the by-pass chamber 64 is conducted by appropriate ducts 66 downward through the body 10 of the tool to a point adjacent the bottom of each circular enlargement 36 for the discharge of quch 1uid to lubricate the cutters, as best indicated in The valve 60 is to be elevated from its closed position of Fig. 2 to its open position of Fig. 3 by the last increment of movement of the piston 22. This is accomplished by engagement of the top of the frusto-conical surface 23 of the piston 22 with an annular lifting shoulder 68 (Fig. 2) provided adjacent the base of that portion of the conduit 40 which reciprocates in the reduced axial bore 41 of the body 10.

The valve 60 at the upper end of the conduit 40, which slides in the body 10, performs several functions. When mud pressure is rst applied through the drill pipe P and the mud bore 12, only a small portion of the pressure is transmitted through the bleeder ports and as a consequence adequate pressure is supplied to the axial passage 42 through the conduit 46 to supply the enlarged bore 43 in the conductor pipe 44 and the surrounding pocket 53 at the under side of the piston 22 at the bottom of the cylinder 20 for elevation of the piston 22. When the piston 22 has elevated the conduit 40 into the position of Fig. 3 by reason of engagement with the annular lifting shoulder 68, the opening of the valve 60 results in the flow of such a large proportion of the fluid to the ducts 66 that the pressure shown on the mud gage at the surface notities the driller that the cutters have been extended into operative position, so that he may start rotation of the drill pipe P to eect the required reaming. The supply of mud passed by the valve 60 when elevated also provides for adequate lubrication of the respective cutters 16.

When the piston 22 is elevated from the positionof Fig. 2 to the position of Fig. 3, it elevates at the same time one or more (three illustrated) collapsing pins 70 which are positioned in diagonally disposed bores 72 so that their lower ends bear upon the frusto-conical surface 23 of the piston 22. When these pins 70 have been raised to the position of Fig. 3, portions of their upper ends are projected within the path of the lower end of the well casing C, so that upon subsequent withdrawal of the tool, after application of drilling mud has been discontinued, such upper ends of the pins will strike the lower end of the casing and positively return the piston 22 to its inoperative position of Fig. 2, so that return of the cutting Wheels 16 and their arms 15 by the lower end of the casing may be positively effected if gravity return has not previously resulted.

When the piston 22 is raised from the position of Fig. 2 to the operative position of Fig. 3, elevation of the piston-like'expander 24 by means of the conductor pipe 44 is automatically effected, as previously indicated. During such movement of the expander 24, by reason of a frusto-conical cam face 75 at its upper end, Fig. 3, all of the shoes 25 are swung outward from their collapsed positions of Figs. l, 2,-and 7 to their extended piloting positions as indicated in Fig. 3 and in the single broken line position of Fig. 7. To provide for the swinging movement each shoe 25 is pivoted at one end upon a vertical pivot pin 76 whose upper and lower ends are positioned in bores in the terminal nose piece 26 and are held against longitudinal displacement by appropriate set screws 76a (Figs. 2 and 3) whose heads are located within downward extensions of the vertical bores for the lower portions of the pivot pins 76. The outer portion of each shoe 25 is formed on the arc of a circle, as best seen in Fig. 7, the upper and lower sides of the swinging end of each shoe converging at 77 as best indicated in Figs. l and 3, the inner portion of the lower converging side 77 terminating in a cam face 73 (Fig. 3) for engagement by the frusto-conical cam face 75 at the upper end of the expander 24.V Thus, the cam action between the faces 75 and 78 as the expander 24 is elevated yextends the shoes 25 from the collapsed positions of Figs. l and 2 to the projected positions of Fig. 3. At all times drilling mud passing through the conductor pipe 44 carrying the expander 24 discharges from the lowermost cylinder 46 by way of a small discharge port 80 at the tip of the nose piece 26.

Should it be desired for any reason not to employ the piloting shoes 25, the terminal nose piece 26 may be replaced with a simple nose piece 26a, as in Fig. 9, which is provided with a bore 46a to receive the lower end of a conductor pipe 44 which would not require the expanding piston 24. The lower end of the bore 46a would be vented through a port 80a in the same manner as with the other form.

The operation has been generally outlined in connection with the above description of the construction and arrangements of the various parts. Briefly, when the hole enlarger is lowered through the casing C on the drill pipe P, the cutters 16 and their carrying arms 15 are retracted and the piloting shoes 25 are likewise retracted, such positions of the various parts being those of Figs. 1 and 2. When the instrument has passed below the lower end of the casing C and it is desired to commence underreaming, mud pressure is applied in a conventional manner through the drill pipe P to the bore 12 of the body 1t). Primarily, this pressure is applied to the passage 42 of the conduit 40 so that it supplies the enlarged conductor bore 43 in the upper end of the conductor pipe 44 carried by the piston 22. The pressure within the enlarged bore 43 is transmitted by way of the side ports 55 to the lower portion of the cylinder 20 and the pocket in the under side of the piston 22. Since the lower end of the cylinder 20 is sealed off by the transverse disc 50, the accumulated pressure, in conjunction with the influence of the counterbalancing spring 52, causes the piston 22 to rise and carry with it the conductor pipe 44 and the expander 24 on the lower end thereof. As the piston 22 rises, the frusto-conical cam surface 23 at its upper end engages with the rounded inner cam faces 34a at the lower ends of the inner bifurcations 34 of the cutter arms 15 so that these arms and the cutters 16 are gradually projected from their inoperative retracted positions of Figs. 2 and 6 to the extended underreaming positions of Fig. 3 lso that, upon lowering of the instrument by means of the drill pipe P, it will cut away shoulders of the wall W of the well as indicated in Fig. 3.

As the piston 22 is elevated, the incidental simultaneous elevation of the conductor pipe 44 and the expander 24 results in engagement of the frusto-conical cam face 75 at the top of the expander 24 with the inner cam faces 73 at the swinging ends of expander shoes 25 so that the latter are moved to the operative position of Fig. 3 which is indicated also by broken lines in Fig. 7.

Between commencement of mud circulation to the instrument and completion of the extension of the cutting wheels 16 to operative position, the bulk of the traveling mud will have passed through the conduit 40 and the conductor pipe 44, but a small proportion will have been by-passed through the ports 65 in the valve 60 Aon the upper end of the conduit 40 to supply mud in limited quantities to the cutter wheels 16 by way of the lubrieating ducts 66.

As the piston 22 approaches the upper limit of its movement, which is a sliding movement along the conduit 40, the reduced extremity of the piston 22 strikes the shoulder 68, provided at an intermediate point of the conduit 40 adjacent the lower end of the bore 41, and raises the conduit 40 suiliciently to lift the valve 60 at its upper end from the seat 62 and permit free passage of mud around the valve 60 into the mud by-pass chamber 64 so that mud under approximately full pressure may travel through the lubricating ducts 66 to discharge suflicient mud adjacent to the cutting wheels 16 for proper lubrication of the latter. Such opening of the valve 60 will cause a sharp drop in mud pressure to appear on the conventional mud pressure gage at the surface of the well7 and this pressure drop will be a signal to the operator that the cutter wheels 16 and the piloting shoes 25 are in extended operative positions. Thereupon the operator may cause rotation of the drill pipe P in a conventional manner to effect the required underreaming and thereby enlarge the hole. Y

In the application of mud pressure to the instrument,

l6 itis preferable that the operator apply the pressurerather gently Aby corresponding control of the pump so :that parts may be moved gradually from their inoperative positions to their operative positions. Under these circumstances, the mud pressure drop at the time of the opening of the valve 60 ordinarily can be more readily observed. A valuable feature of the piston 22 in addition to actuating the parts as previously described, is that, when in elevated position, it is disposed behind the lower ends of the cutter arms 15 so that the cutting wheels 16 are locked in their projected positions at all times during application of mud pressure and during operation of the tool. An important feature in the method of routing the mud stream is found in the fact that by transmitting the mud pressure by way of the ports V5 5 in the conductor pipe 44 to the portion of the cylinder 20 below the piston 22 and to the mud pocket 23 at the under side of the piston a minimum of uid travel within the corresponding annular chamber between the pipe 44 and the walls of the cylinder 2t) occurs, and as a consequence there results a minimum deposit of solids that are characteristically carried in the mud. Also -by employment of the diagonally disposed piston-returning pins 70, movement downward of the piston 22 and the expander 24, following discontinuance of application of mud at the end of the underreaming operation, is assured so that the arms 15 and their cutters 16 together with the shoes 25 may be definitely returned to collapsed positions upon striking the lower end of the casing C, especially in conjunction with incidental rotation of the tool, should the parts not have otherwise previously returned to their retracted positions.

It is to be noted that, by disposition of the piston 22 generally below the cutter wheels 16, a convenient arrangement is provided for actuating the expander 24 and therpilot shoes 25 in the nose piece 26 hy'and simultaneously with the piston operation.

I claim as my invention:

1. In combination in an underreaming tool for deep wells: an elongated body adapted to be carried on the lower end of drill pipe, and having an elongated outwardly opening pocket provided in a side portion'thereof, an upper fluid bore, and a cylinder in a lower portion of said body adjacent the lower end of said pocket; a swinging arm pivotally mounted in said pocket to swing in a plane extending longitudinally of said body; cutting means carried on the swinging end of said arm to engage and cut wall portions of a well hole when projected outward; a piston in said cylinder and having cam means arranged adjacent to and engageable with a cam yportion on thelower end of said swinging arm to project outward said lower end of said arm and said cutting means thereon; and conduit means extending through said body, said cylinder and said piston and having parts communicating with said cylinder for the application of iiuid pressure from said drill pipe and uid bore to the under side of said piston to elevate said piston for engagement of said cam means with said cam portion to project said cutting means, said conduit means providing a through passage to the lower end of said tool and discharging below said piston and cylinder by way of said passage, said communication with said cylinder being non-circulating communication .between said passage and said cylinder through said ports, said cylinder being free from circuitcreating outlets, whereby to avoid circulation through said cylinder of mud traveling through said passage.

2. A combination as in claim l wherein said conduit means is slidable in said body and reaches up to'said uid bore .and has valve means at its upper end and means on an intermediate portion above said cylinder for engagement by an upwardly moving portion of said piston to raise said conduit means and open said valve for release of pressure within said conduit means and the lower portion of said cylinder.

3. A combination as in claim 2 wherein said body has a by-pass from a position adjacent the upper portion of said conduit means to by-pass fluid from said upper uid bore when said valve is open and discharge such by-pass fluid from the tool.

4. A combination as in claim l wherein said conduit means extends upward to said fluid bore and has a valve means at its upper end and is slidably mounted in a bore in said body below said fluid bore, said body having seat means in said iluid bore engageable by said valve means, said piston having means engaging said conduit means to 7 lift the same and open said valve means for relief of pressure in said conduit means and the lower portion of said cylinder.

5. A combination as in claim 2 wherein said body has by-pass means leading from a position adjacent the upper end of said conduit means to a position adjacent said cutting means to pass uid to said cutting means to klubricate the latter.

6. A combination as in claimv 1 wherein said cylinder extends alongside said cutting means and is in communication with said pocket, said piston closing the upper portion of said cylinder at all times and being elevatable alongside said cutting means and arm to engage the same and lock them in projected position.

7. A combination as in claim 1 including a central conduit extending from said piston and through the bottom of said cylinder to form a uid pocket below said piston and between said central conduit and the wall of said cylinder, said central conduit having a central passage entirely therethrough and a port laterally therethrough for the sole passage of pressure fluid to said fluid pocket whereby to limit iluid circulation in said fluid pocket and reduce accumulation of solids therein.

8. In combination in a hole-enlarging tool for deep wells: an elongated body adapted to be lowered into a well on the lower end of drill pipe, said body having elongated pockets therein opening laterally therefrom, said body having an axially disposed cylinder therein lying alongside the lower portions of said pockets and extending downward therefrom, said cylinder being in communication with the lower ends of said pockets; cutting means normally disposed in lower portions of said pockets; mounting arms pivotally mounted at their upper ends in upper portions of said pockets and carrying said cutting means on their lower ends to move said cutting means outward in vertical planes; and piston means disposed in said cylinder and having cam means at its upper portion to engage and project said lower ends of said arms and their cutting means, said body having passage means for conducting pressure fluid to the under side of said piston to raise the same for projecting said cutting means, and said piston being guided in and closing the upper end of said cylinder adjacent the lower ends of said pockets at all times.

,9. In combination in a hole-enlarging tool for deep wells: an elongated body adapted to be lowered into a well on the lower end of drill pipe, said body having elongated pockets therein opening laterally therefrom, said body having an axially disposed cylinder therein; arms pivoted in said pockets to swing therefrom; cutting means mounted on the swinging ends of said arms to be projected outward; a piston disposed in said cylinder to actuate said arms and cutting means, said body having passage means therethrough to supply pressure fluid to the under side of said piston to raise the latter; a valve stem adjacent said passage means and having a valve to close said passage means, said valve stern being slidable in said piston and having means disposed in the path of and for operative engagement with said piston so that said valve may be opened by piston movement for bypassing pressure fluid and regulating application of pressure uid to said piston.

lO. A combination as in claim 9 wherein said passage means comprises a conduit extending axially through an axial bore in said body and an axial bore in said piston to the lower portion or" said cylinder at the under side of said piston, said conduit constituting said valve stem and carrying said valve at its upper end.

11. A combination as in claim 10 including: a pilot nose on the lower end of said body below said cylinder; projectable pilot means carried by said nose; and means secured to' said piston and extending downward into said nose to said pilot means to actuate and project the latter upon operation of said piston.

l2. A combination as in claim l1 wherein said means secured to said piston is a conduit aligned with said bore in said piston.

13. A combination as in claim l2 wherein said conduit is provided with ports communicating with the portion of the cylinder below said piston to transmit uid pressure for raising the piston.

14. A combination as in claim l including: a nose at the lower end of said body below said cylinder; and conduit means secured to said piston and extending downward therefrom through and beyond said cylinder in alignment with said bore in said piston, said conduit means having ports communicating with the cylinder below said piston to transmit actuating uid pressure to the underside of said piston.

15. A combination as in claim 14 wherein said conduit means below its ports is provided with a venting passage and such venting passage is restricted to build up actuating back pressure.

16. A combination as in claim 9 including Huid-venting means controlled by said valve for reducing iluid pressure to said piston.

17. In combination in a hole-enlarging tool for deep wells: an elongated body adapted to be lowered into a well on the lower end of drill pipe, said body having laterally opening pockets therein, and an axial cylinder; arms pivotally mounted in said pockets to be projected outward and provided with wall-engaging means; a piston movable in said cylinder to engage and project said arms and wall-engaging means; means for supplying iluid pressure to said tool to actuate said piston upward to project said arms; and return means movably mounted in an angular position in said body, a lower portion of said return means being positioned with respect to said piston to be moved under influence of said piston to project angularly upward and outward from said body in position to engage the lower end of casing in a well, said return means being returnable upon striking said casing end to return said piston to initial position.

18. In combination in an underreaming tool for deep wells: an elongated body adapted to be carried on the lower end of drill pipe, and having an elongated outwardly opening pocket provided in a side portion thereof, an upper iluid bore, and a cylinder in a lower portion of said body adjacent the lower end of said pocket; a swinging arm pivotally mounted in said pocket to swing in a plane extending longitudinally of said body; cutting means carried on the swinging end of said arm to engage and cut Wall portions of a well hole when projected outward; a piston in said cylinder and having cam means arranged adjacent to and engageable with a cam portion on the lower end of said swinging arm to project outward said lower end of said arm and said cutting means thereon; conduit means extending through said body and said piston and communicating with the lower portion of said cylinder for the application of uid pressure from said drill pipe and Huid bore to the under side of said piston to elevate said piston for engagement of said cam means with said cam portion to project said cutting means; a pilot nose on the lower end of said body; laterally projectable pilot means on said pilot nose; and means connected to said piston and actuable thereby to engage and project said pilot means.

19. In combination in a hole-enlarging tool for deep wells: an elongated body adapted to be lowered into a well on the lower end of drill pipe, said body having elongated pockets therein opening laterally therefrom, said body having an axially disposed cylinder therein lying alongside the lower portions of said pockets and extending downward therefrom, said cylinder being in communication with the lower ends of said pockets; cutting means normally disposed in lower portions of said pockets; mounting arms pivotally mounted at their upper ends in upper portions of said pockets and carrying said cutting means on their lower ends to move said cutting means outward in vertical planes; piston means disposed in said cylinder and having cam means at its upper portion to engage and project said lower ends of said` arms and their cutting means, said body having passage means for conducting pressure fluid to the under side of said piston to raise the same for projecting said cutting means; a pilot nose carried by the lower end of said body; projectable piloting means carried in side pockets in said nose and projectable laterally therefrom; and means connected with said piston means and positioned for engaging said piloting means to project the latter upon movement of said piston means for projection of said cutting means.

2.0. A combination as in claim 19 wherein said means connected with said piston means is slidably mounted in said nose.

21. In combination in an underreaming tool for deep wells: an elongated body adapted to be carried on the lower end of drill pipe, and having an elongated outwardly opening pocket provided in a side portion thereof, an upper fluid bore, and a cylinder in a lower portion of said body adjacent the lower end of said pocket; a swinging arm pivotally mounted in said pocket to swing in a plane extending longitudinally of said body; cutting means carried on the swinging end of said arm to engage and cut wall portions of a Well hole when projected outward; a piston in said cylinder and having its upper end arranged adjacent to and engageable with a lower portion of said swinging arm to project outward the lower end of said arm and said cutting means carried thereby; and conduit means extending downward through said body, said piston and said cylinder and communicating with said cylinder for application of fluid pressure from said drill pipe and uid bore to the under side of said piston to elevate the piston and project said cutting means, said cylinder having the upper portion of its wall terminating adjacent the lower ends of said swinging arm and said pocket, and said upper end of said piston being in engagement with said cylinder wall in fluid-sealing relation and being guided by said wall and thereby stiftening said body adjacent said cylinder wall.

22. In combination in an underreaming tool for deep wells: an elongated body adapted to be carried on the lower end of drill pipe, and having an elongated outwardly opening pocket provided in a side portion thereof, an upper fluid bore, and a cylinder in a lower portion of said body adjacent the lower end of said pocket; a swinging arm pivotally mounted in said pocket to swing in a plane extending longitudinally of said body; cutting means carried on the swinging end of said arm to engage and cut wall portions of a well hole when projected out- Ward; a piston in said cylinder and having its upper end arranged adjacent to and engageable with a lower portic-n of said swinging arm to project outward the lower end of said arm and said cutting means carried thereby; and conduit means extending downward through said body, said piston and said cylinder and communicating with said cylinder for application of iiuid pressure from said drill pipe and iluid bore to the under side of said piston to elevate the piston and project said cutting means, said conduit means providing a through passage to the lower end of said ltool and discharging below said piston and cylinder by way of said passage, said conduit means having parts to said cylinder and said communication with said cylinder being non-circulating communication between said passage and said cylinder through said ports, said cylinder being free from circuit-creating outlets, whereby to avoid circulation through said cylinder of mud traveling through said passage.

References Cited in the ile of this patent UNITED STATES PATENTS 1,611,282 Samuelson Dec. 21, 1926 1,786,484 Duda Dec. 30, 1930 1,878,260 Bunker Sept. 20, 1932

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