US2796234A - Full bore deflection drilling - Google Patents

Description

June 1-8, 1957 W. L. MANN FULL BORE DEFLECTION DRILLING Filed June 8. 1953 I N VEN TOR. WILLIAM L Mnulv United States Patent FULL BORE DEFLECTION DRILLING William L. Mann, Arcadia, Calif.

Application June 8, 1953, Serial No. 360,244

6 Claims. (Cl. 255-1.6)

This invention relates to a novel full bore deflection drilling tool, and more particularly, to a deflection tool for use in rotary type drilling operations which may be operated from the surface of the bore hole.

It is common practice to drill oil wells in directions other than the vertical. For example, a large oil deposit may be known to exist under a given body of water. In such instances, it is oftentimes more convenient to construct the derrick and conduct the drilling operations from an adjacent land station, the bore hole itself being caused to veer off from the vertical to penetrate points beneath the body of water. In other instances, it may be desired to deflect the direction of the drilling to avoid certain types of earth formations which are diflicult to penetrate. Likewise, it may be desirable to maintain the bore hole substantially vertical when, due to different types of earth strata, the bore hole drill bit has a tendencly to veer off in undesired directions.

The conventional method of deflecting the direction of a bore hole is to use what is known as a whipstoc The whipstock is a wedge-shaped, semi-cylindrical, metallic casting adapted to be lowered into the bore hole with the drill and cause the drill, by a wedging action, to penetrate the formations at a slight angle to the axis of the bore hole. Generally, a smaller diameter drill bit is employed with the whipstock in order that the whipstock may fit within the original bore hole and properly effect the desired deflection. After the bore hole is started off at the desired angle, the whipstock is removed and the smaller diameter hole suitably reamed with the conventional sized drill bit. The major disadvantage of the whipstock method of deflection drilling is the great time and labor consumed in its operation. Not only must the entire string of drill pipe be removed in order to attachthewhipstock to the end of the drill bit collar, but after the initial deflection in the bore has been effected, it is again necessary to remove the entire string of drill pipe to replace the bit with a larger-sized bit to ream out the smaller diameter hole.

In an effort to obviate, at least to some extent, these major disadvantages of the whipstock, there have been developed bore hole deflection tools having a movable element in the form of a bowed spring, for example, adapted to engage the side of the bore hole to push the drill collar and bit to one side. In. such instruments, it has still been necessary to employ a smaller diameter drill bit, in order to permit a deflecting movement of the drill within the bore hole. There was thus the same problem of having to ream out the hole once it had been started in the desired deflected direction. Furthermore, it is not posssible with these instruments to carry on an elfective drilling operation simultaneously with a deflecting operation. Nor is it generally possible to control accurately the precise degree of deflection without having to remove the whole string of drill pipe and make suitable adjustments on the deflecting tool itself.

- The present invention has for its primary object the 1 provision of a full bore deflection drilling tool. By full ICQ 2 bore is meant that the deflected bore is of the same diameter as the initial bore hole whereby the heretofore necessary reaming operations are entirely obviated.

Another object of the invention is to provide a full bore deflection drilling tool which may be operated simultaneously with the drilling operation. In other words, the full weight of the drill string can be used While drilling without interfering in any way with the deflecting mechanism of the tool. Thus, the bore hole may be deflected and drilled simultaneously.

Another very important object is to provide a deflecting instrument which may be controlled from the surface of the bore hole, both as to its operation and as to the precise degree of deflection desired. This feature results in an inestimable saving in labor and costs in drilling operations, inasmuch as the removal of the complete drill string for adjustment purposes is entirely avoided.

Another object of the invention is to provide an extremely accurate and reliable hydraulic system for operating the deflecting tool, which operates in response to the pressure of the mud circulating through the bit collar. In this connection, there is provided a rugged, mechanically simple, and reliable control means at the surface of the bore hole for controlling the precise values of this mud pressure.

These and additional objects and advantages of. the present invention are attained by providing a generally cylindrical body adapted to be secured at one end to the end of the string of drill pipe, and to receive a bit collar at its other end. The normal sized drilling bit is used in this arrangement. Rotatably mounted about the cylindrical body (intermediate its ends) is a sleeve section, coaxial with the cylindrical body and including a carriage pad or frame member adapted to be extended laterally from one side of the sleeve to engage a side wall of the bore hole. For this purpose, there is provided a hydraulic system, insolated from the mud circulating within the cylindrical body but adapted to respond to the pressure of this mud. The arrangement is such that when the pad member is extended into engagement with the side wall of the bore hole, the full weight of the drill string may be employed and the drilling operation continued without interruption, the cylindrical body and drill bit collar turning relative the sleeve.

An auxiliary means for controlling the pressure of the mud within the drill pipe string is provided at the surface of the bore hole, and this control will in turn determine the engaging force exerted by the pad member against the side of the bore hole, thereby accurately controlling the degree of deflection force applied to the bit.

Preferably, suitable rollers are provided on the engaging surface of the pad member so that the pad may roll along the side wall of the bore hole as the drilling progresses. There is also provided in the preferred embodiment of the invention, a further arm on the cylindrical sleeve section adapted to be extended to engage an opposite side wall of the bore hole at a level different from the level at which the pad member engages the side wall, whereby a deflecting torque is applied to the tool, permitting much more accurate control of the degree of deflection. In other words, this auxiliary arm maintains the drill pipe string substantially centered in the Well bore while the bore is being deflected off at an angle.

A better understanding of the invention will be had by referring to the accompanying drawings, in which:

Figure 1 illustrates a simultaneous deflecting and drilling operation being conducted in an oil well bore hole;

Figure 2 is an enlarged elevational view, partly in section, showing a preferred form of the deflecting tool of the present invention;

Figure 3 is a smaller view, partly in section, of the deflecting tool with the deflecting pad member extended;

Figure 4 is a cross-sectional view of the bore hole, showing the disposition of the various elements of the deflecting tool in extended position; and

Figure 5 is an enlarged cross-sectional view of the check valve means of the deflecting tool shown in Figure 2.

Referring to Figure 1, there is shown a bore hole containing a string of drill pipe 11 adapted to be rotated by the conventional rotary table 12. Secured to the lower end of the string of drill pipe 11 is the full bore deflecting tool 13 and full bore drill bit 14. As shown in Figure 1, the bore hole is being veered off to the left a controlled amount by means of the deflecting tool 13.

The amount of deflection is accurately controlled by controlling the pressure of the drilling mud within the deflecting tool. As shown in the upper part of Figure 2, this control comprises the conventional mud pump which may deliver mud under pressures ranging from 250 to 2000 pounds, an aperture control valve 21, and a suitable pressure gauge 22, all connected in the conduit leading to the rotary swivel. In the conventional rotary type of drilling, mud is generally pumped down through the drill pipe string, and passed up between the string and the side Walls of the bore hole, carrying the chips from the drilling up to the surface.

As shown in Figure 2, the full bore deflection tool itself is made up basically of three sections, the. first section 23 being adapted to be secured to the end of the drill pipe string, and the second section 24, including a bit collar 24' at its lower end, adapted to be secured to the drill bit. This second section 24 has a reduced diameter portion along its upper end about which there is rotatably mounted the third section 25 in the form of a cylindrical sleeve. A thrust collar bearing support 25' is secured to the upper end of sleeve 25 as by means of a tight frictional fit, and may be considered a continuation of the sleeve.

Insofar as the construction so far described is concerned, the first section 23 and second section 24 may be considered as a cylindrical body having a reduced diametrical portion intermediate its ends which rotatably mounts the sleeve 25 and thrust collar 25. The reduced diameter portion defines upper and lower shoulders A and B respectively which confine the longitudinal movement of the sleeve 25 and thrust collar 25'. As shown, ball bearings 26 are disposed between the upper shoulder A and the upper end of the collar 25', while a journal bearing 27 is disposed adjacent the lower shoulder B between an inner annular circumferential portion of the cylindrical sleeve 25 and the reduced diameter portion of the section 24. This construction permits the sleeve member 25 and collar 25 to remain stationary while the first section 23 and second section 24 rotate relative the sleeve and collar, even though under compression due to the weight of the entire drill string. The bearings 26 thus operate as thrust bearings, and will transmit through the collar and sleeve to the drill bit the entire longitudinal force exerted downwardly on the drill string without interfering with the independent operation of the sleeve member 25.

A central mud passage 28 is provided in the second section 24 for passing mud from the mud pump 20 to the end of the drill bit, as indicated by the arrows. This passage includes two lateral ports 29 leading to an an nular chamber R defined by the lower end of the collar 25', an annular recessed portion in the sleeve, and the outer wall of the section 24. An annular piston 30 is positioned within the annular chamber R, and is longitudinally movable against a compression spring 31 in the lower portion of the chamber. This lower chamber portion contains a hydraulic fluid 32. The annular piston 30 thus serves to isolate the hydraulic fluid 32 from the mud circulated through the central passage 28 and po t 4 29. However, the piston 30 will accurately transmit the pressure of this mud to the hydraulic fluid.

A passage 33 communicates with the lower section of the chamber R, and then branching into two enlarged openings 33a and 33b, each containing ball check valves 34 and 43, respectively. The branched passages join on the other side of the check valves 34, 43 merging into a channel 36 which communicates with a cup-type movable housing'or cylinder 37 to be described in more detail hereafter.

Referring especially to Figure 5, the check valve 34 includes a ball and a spring-set screw adjustment 35a, the spring-set screw adjustment retaining the ball and check valve 34 against a seat in the opening 33a, when no pressure is being exerted against it.

The check valve 43 consists of a ball only, which is adapted to seat against the seat of the opening 33b under pressure exerted by hydraulic fluid in a radially outward direction.

In assembly, the balls of the check valve 34 and 43 for each of the enlarged openings 33a and 33b, are passed through threaded bores 50 and 51, respectively, formed in the sleeve 25. The set screw adjustment 35 is then set into the opening 33a, a plug 35a being screwed into the bore 50 to seal the upper end of the opening. Adjustment of the set screw 35 is obtained by tightening nut 35b. The bore 51 is sealed by screw 43a to retain the ball in the opening 33b.

From the lower annular portion of the chamber R, the hydraulic fluid 32 passes through the fluid passage 33, the check valve 34 including the set screw adjustment 35, and the fluid passage 36, to a cup-type cylinder 37. This cup cylinder 37 snugly fits over a cylindrical projection 37 adapted to telescopically support the cup cylinder 37. The cup cylinder 37 is secured to.a supporting spring 38, the free end of which is rigidly secured to a carriage frame or pad member 39. This pad member 39 is thus resiliently mounted with respect to the cup cylinder 37 by the spring 38. The carriage frame or pad member 39 rotatably mounts a pair of rollers 40, the periphery of the rollers extending a small distance beyond the end surface of the pad member to engage the side wall of the bore hole and roll therealong as the drilling progresses. In retracting the pad member, the hydraulic fluid passes back through passage 36 and a branch line containing the check valve 43 to the lower portion of the annular chamber R.

As shown in Figures 2 and 3, the pad member 39 is provided with a key 41 adapted to fit within a complemental keyway 41a in the second section bit collar 24' whereby the disposition of the pad member and that of the cylindrical sleeve 25 with respect to the drill bit is determined. The degree of extension of the pad member 39 is limited by the small shoulder 42 against which a corresponding shoulder on the pad member itself abuts.

To further improve directional control of the tool, there is provided another fluid passage 44 communicating with the passage 36 below the check valve 34 as indicated by the dotted lines, and which extends, in semi-circular fashion, to the opposite side of the sleeve 25, thence extending upwardly to terminate within a cup-type cylinder 45 adapted to telescopically slide on a cylindrical projection 45. The exterior of the cup-type cylinder 45 is smoothly rounded to form a camming surface adapted to bear against an extension arm 46 pivotally secured to the sleeve 25 as at 47. Ann 46 is thus adapted to engage an opposite side Wall of the bore hole at a level difierent from the level of the point of engagement of the pad member 39. The pivoting movement of arm 46 is limited by the bore hole side wall and this arm will thereby limit the telescoping movement of the cup-type cylinder 45 with respect, to the projection 45'. Figure 3 shows the pad member 39 and arm 46 in their extended positions.

In the operation of the full bore deflection tool, the set screw 35 for the check valve 34 on sleeve 25 is initially adjusted to prevent this check valve, from opening at any pressure equal to or less than the contemplated static mud pressure in the bore hole. This static pressure is proportional to the height of the mud column above the instrument, and if it is contemplated that during a single drilling operation a depth no greater than a certain maximum amount is to be drilled, the set screw 35 is adjusted not to openunless the mud pressure at this maximum depth is exceeded.

The first section 23 of the tool is then secured to the end of the string of drill pipe, the drill collar 24 of the second section secured to the drill bit, and the instrument lowered into the bore hole in the usual manner. In the course of the drilling operation, the pressure of the circulating mud may be very accurately adjusted by means of the aperture valve 21 at the surface of the bore hole which serves merely to change the aperture through which the mud from the pump is passing, thereby causing a pressure drop inversely proportional to the area of the aperture across this valve. This controlled pressure is indicated by the pressure gauge 22. When it is desired to deflect the bore hole from its initial vertical direction for one reason or another, the desired degree of deflection is first determined. This degree of deflection will determine the necessary pressure to be applied to the side wall engaging pad member 39 through the medium of the spring 38 and cup cylinder 37 The circulating mud pressure is adjusted according to this pressure by means of the valve 21.

The controlled mud pressure is then effected and will act on the annular piston 30 in the chamber R of the cylindrical sleeve section 25 of the deflection tool, causing this piston to move downwardly against the force of the compression spring 31 and compress the hydraulic fluid 32 with a corresponding pressure. The increased mud pressure over and above its static value at the specified depth in the bore hole will cause the check valve 34 to open and admit the hydraulic fluid through the passage 36 to the interior of the cup cylinder 37, causing this cylinder 37 and pad member 39 to telescope laterally in a direction generally normal to the axis of the tool. This extended position is clearly depicted in Figure 3. The provision of the relatively stiff supporting spring 38 between the pad member and the cup cylinder, will cushion the engaging force of the pad against the side wall of the bore hole and permit some variations in the position of the pad member 39 due to possible irregularities in the bore hole side wall. Such slight movements due to these variation could not easily be accommodated by the hydraulic fluid 32 inasmuch as this fluid is essentially 4 incompressible.

Simultaneously with the movement of the pad member 39 against the side wall of the bore 10, the arm 46 on the opposite side of the sleeve 25 is caused to move into engagement with the opposite bore hole wall by virtue of the fluid pressure in passage 44 acting on the inverted cup cylinder 45. Extension of this cylinder 45 laterally with respect to the sleeve 25 cams the pivoted arm 46 outwardly against the bore hole wall. Therefore, there is applied a coupling force or torque to the deflecting instrument which serves to bias the drill bit to one side of the bore hole. In view of the fact that the passage 44 is in communication with the passage 36, the arm actuating cup cylinder 45 is also controlled by the setting of the check valve 34. The provision of the roller elements on the pad member 39 permits the pad member to roll along the side wall of the bore hole as the drilling progresses.

It is to be particularly noted that the construction of the deflecting tool of this invention permits the full weight of the drill string to be applied to the drill bit through the thrust bearings 26 while the collar 25' and sleeve member 25 are held stationary by the pad member.39 bearing against the bore hole side wall. It is also to be noted that since the degree of deflection of the drill will depend upon the force exerted by the pad member 39 against the bore hole. side wall, this degree may be accurately controlled from the surface inasmuch as the pressure of the pad member can be controlled from the surface by adjusting the mud pressure.

The provision of the arm 46 aids in maintaining the drill string centered in the bore hole.- In the absence of such an arm, the action of the pad member would simply be to push the whole drill string pipe to one side of the bore hole. While some deflection of the direction of the bore hole could be accomplished in this manner, a much more satisfactory degree of control is had by the provision of the arm 46, permitting a better control of the degree of deflection.

When it is deemed that the deflection has been properly eflected the desired number of degrees, the mud pressure may be decreased by closing the aperture valve 21, which decrease will permit the compression spring 31 to move the annular piston 30 in the sleeve 25 upwardly, causing the hydraulic fluid 32 to pass from the interior of the cup cylinder 37 through the check valve 43, to the annular chamber R below the piston 30. The pad member is thus hydraulically retracted and the key 41 will fit within the keyway 41a of the collar section 24 by virtue of the rotation of this latter section relative to the sleeve serving to bring the key and keyway around into registering position within at least one rotation. When the pad member locks into the keyway 41a, it will then rotate with the drill bit. Similarly, the decrease in the mud pressure permitting the compression spring 31 to return the annular piston 30 to the upper portion of the chamber will cause the extension arm 46 to be hydraulically retracted into the position shown in Figure 2.

By means of the present invention, there has thus been provided a full bore deflecting tool which may be accurately controlled from the surface of the bore hole, and which completely obviates the prior disadvantages in deflection drilling, to wit, the necessity of removing the entire drill string from the bore hole for adjustment or attachment of a whipstock deflecting tool; the necessity of reaming the deflected bore; and the enormous expense involved in general in the loss of rig time resulting in prior methods and means for deflection drilling. Fur: thermore, the hydraulic control system of the present in: vention provides a nicety of adjustment as to the degree of deflection never before attained.

While a preferred embodiment of the invention has been disclosed, it is to be understood that the described principles may be employed in modified apparatus within the scope of one skilled in the art. The invention is therefore not to be thought of as limited to the specific embodiment disclosed.

I claim:

1. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter portion intermediate its ends and being inflexible, therebetween, one end being adapted for rigid connection to a string of drill pipe, and the other end being adapted for rigid connection to a drill bit; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said cylindrical body and cylindrical sleeve section including coaxial central passages in communication with the drill pipe string and bore hole whereby mud may be passed therethrough, said sleeve section having an inner annular recessed portion defining, with the outer wall of said reduced diameter portion, an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved by hydraulic means laterally from one side of the sleeve for engagement with the side wall of said bore hole, said hydraulic means comprising at least one lateral port passage from the central passage in the cylindrical body communicating with said annular chamber in said sleeve section, an annular piston reciprocall mounted in said chamber whereby mud pressure may e exerted on one side of said piston, hydraulic fluid on the other side of said piston, a first fluid passage in said sleeve section leading from said hydraulic fluid, said first passage terminating in a first projection on the exterior of said sleeve section, a cup-shaped cylinder telescopilcally slidable in a lateral direction under hydraulic pressure over said projection so as to move said pad member secured to said cylinder laterally against said side wall; an arm member attached to said sleeve section and adapted to be moved simultaneously with said pad member by hydraulic means, from an opposite side of the sleeve from said pad member into engagement with the opposite wall of the bore hole at a level diflerent from the level of the carriage pad member whereby a pivoting force is applicd to said sleeve for deflecting said tool in said bore hole, said hydraulic means comprising a second fluid passage communicating with said hydraulic fluid on the other side of said piston and leading therefrom to terminate in a second projection; and a hydraulically-operable cylinder slidable over said second projection and adapted to abut said arm member in camming engagement.

2. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter 1.

portion intermediate its ends and being inflexible therebetween, one end being adapted for rigid connection to a string of drill pipe and the other end being adapted for rigid connection to a drill bit; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said cylindrical body and cylindrical sleeve section including coaxial central passages in communication with the drill pipe string and bore hole where-by mud may be passed therethrough, said sleeve section having an annular recessed portion defining, with the outer wall of said reduced diameter portion, an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved laterally from one side of the sleeve for engagement with the side wall of a bore hole; an arm member attached to said sleeve section and adapted to be moved from an opposite side of the sleeve into engagement with the opposite wall of the bore hole at a level different from the level of the carriage pad member; and hydraulic means for simultaneously moving said pad and arm members whereby a pivoting force is applied to said sleeve for deflecting said tool in said bore hole, said hydraulic means comprising at least one lateral port passage from the central passage in the cylindrical body communicating with said annular chamber in said sleeve section; an annular piston reciproca-bly mounted in said chamber, whereby mud pressure may be exerted on one side of said piston; hydraulic fluid on the other side of said piston; a fluid passage in said sleeve section leading from said hydraulic fluid and terminating in a first cylindrical projection on the exterior of said r sleeve section; a cup-shaped cylinder telescopically slidably under hydraulic pressure over said projection; and means securing said cup-shaped cylinder to said carriage pad member.

-3. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter portion intermediate its ends and being inflexible therebetween, one end being adapted for rigid connection to a string of drill pipe and the other end being adapted for rigid connection to a drill bit; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said cylindrical body and cylindrical sleeve section including coaxial central passages in communication with the drill pipe string and bore hole whereby mud may be passed therethrough, said sleeve section having an annular recessed portion defining, with the outer wall of said reduced diameter portion, an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved laterally from one side of the sleeve for engagement with the side wall of a bore hole; an arm member attached to said sleeve section and adapted to be moved from an opposite side of the sleeve in-to engagement with the opposite wall of the bore hole at a level different from the level of the carriage pad member; and hydraulic means for simultaneously moving said pad and arm members whereby a pivoting force is applied to said sleeve for deflecting said tool in said bore hole, said hydraulic means com-prising at least onelat eral port passage from the central passage in the cylindrical body communicating with said annular chamber in said sleeve section; an annular piston reciprocably mounted in said chamber, whereby mud pressure may be exerted on one side of said piston; hydraulic fluid on the other side of said piston; a fluid passage in said sleeve section leading from said hydraulic fluid and terminating in a first cylindrical projection on the exterior of said sleeve section; a cupshaped cylinder telescopically slida-ble under hydraulic pressure over said projection; means securing said cup-shaped cylinder to said carriage pad member; and a check valve contained in said fluid passage in said sleeve section adapted to be positioned so as to prevent said hydraulic fluid, below a predetermined pressure, from passing through said valve and operating said pad member.

4. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter portion intermediate its ends and being inflexible therebetween, one end being adapted for rigid connection to a string of drill pipe and the other end being adapted for rigid connection to a drill bit, said cylindrical body including a central passage in communication with the drill pipe string and the drill bit whereby mud may be passed therethrough; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said sleeve section having an inner annular recessed portion defining wit-h the outer wall of said reduced diameter portion an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved laterally from one side of the sleeve for engagement with the side wall of a bore hole; an arm member attached to said sleeve section and adapted to be moved from an opposite side of the sleeve into engagement with the opposite Wall of the bore hole at a level different from the level of the carriage pad member; and hydraulic means for si multaneously moving said pad and arm members whereby a pivoting force is applied to said sleeve for deflecting said tool in said bore hole, said hydraulic means including a passageway from said central passage to said annular chamber, an annular piston re-ciprocably mounted in said chamber and having one end opening to said passageway, a body of hydraulic fluid on the other side of said piston, and hydraulicallybperable cylinder means connected to said pad member and movable laterally relative to said sleeve section, said cylinder means being in communication with said body of hydraulic fluid; and means provided at the surface of the bore hole for controlling the mud pressure action on said annular piston.

5. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter portion intermediate its ends and being inflexible therebetween, one end being adapted for rigid connection to a string of drill pipe and the other end being adapted for rigid connection to a drill bit, said cylindrical body including a central passage in communication with the drill pipe string and the drill bit whereby mud may be passed therethrough; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said sleeve section having an inner annular recessed portion defining with the outer wall of said reduced diameter portion an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved laterally from one side of the sleeve for engagement with the side Wall of a bore hole; an arm member attached to said sleeve section and adapted to he moved from an opposite side of the sleeve into engagement with the opposite wall of the bore hole at a level different from the level of the carriage pad member; and hydraulic means for simultaneously moving said pad and members whereby a pivoting force is applied to said sleeve for deflecting said tool in said bore hole, said hydraulic means 9 including a passageway from said central passage to said annular chamber, an annular piston reciprocably mounted in said chamber and having one end opening to said passageway, a body of hydraulic fluid on the other side of said piston, and hydraulically-operable cylinder means connected to said pad member and movable laterally relative to said sleeve section, said cylinder means being in communication with said body of hydraulic fluid.

6. For use in a bore hole, a full bore directional tool comprising: a cylindrical body having a reduced diameter portion intermediate its ends and being inflexible therebetween, one end being adapted for rigid connection to a string of drill pipe and the other end being adapted for rigid connection to a drill bit, said cylindrical body including a central passage in communication with the drill pipe string and the drill bit whereby mud may be passed therethrough; an inflexible cylindrical sleeve section rotatably mounted on said reduced portion, said sleeve section having an inner annular recessed portion defining with the outer wall of said reduced diameter portion an annular chamber; a carriage pad member attached to said sleeve section and adapted to be moved laterally from one side of the sleeve for engagement with the side wall of a bore hole; an arm member pivoted to said sleeve section and adapted to be moved from an oppo- [0 site side of the sleeve into engagement with the opposite wall of the bore hole at a level different from the level of the carriage pad member; and hydraulic means for simultaneously moving said pad and arm members whereby a pivoting force is applied to said sleeve for deflecting said tool in said bore hole, said hydraulic means including a passageway from said central passage to said annular chamber, an annular piston reciprocably mounted in said chamber and having one end opening onto said passageway, a body of hydraulic fluid on the other side of said piston, and hydraulically-operable cylinder means connected to said pad member and movable laterally relative to said sleeve section, said cylinder means being in communication with said body of hydraulic fluid, and said hydraulic means including hydraulically-operable cylinder means abutting said arm and connected to said sleeve and in communication with said body of hydraulic fluid.

References Cited in the file of this patent UNITED STATES PATENTS 2,173,309 Monroe Sept. 19, 1939 2,316,409 Downing Apr. 13, 1943 2,637,527 Andrews May 5, 1953 2,643,859 Brown June 30, 1953

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