US3131778A

US3131778A - Drilling deflection apparatus

Info

Publication number: US3131778A
Application number: US161329A
Authority: US
Inventors: William C Emerson; Smith Lester
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-12-11
Filing date: 1961-12-11
Publication date: 1964-05-05
Anticipated expiration: 1981-05-05

Description

May 5, 1964 w. c. EMERSON ETAL DRILL-ING DEFLECTION APPARATUS 5 Sheets-Shea?l l Filed Deo. l1, 1961 n w WM CJ f m@ Z INVENTOR` BY f/WL ATTO/CP/VYJ May 5, 1954 w. c. EMERsoN ETAL 3,131,778

DRILLNG DEFLECTION APPARATUS Filed Deo. 11. 1961 3 Sheets-Sheet 2 l VV////c7m C .Eme/Jon 2 ezef" Jm/ 40e INVENTORJ '56- Y WA/@AUM May 5, 1954 w. c. EMERSON ETAL 3,131,778

v DRILLING DEFLECTION APPARATUS Filed Deo. l1, 1961 s sheets-sheet 5 United States Patent Oli ice 3,131,778 Patented May 5, 1964 3,131,778 DRELLlNG DEFLECTN APPARATUS William C, Emerson, RG. Box 355, Saratoga, Tex., and Lester Smith, 2613 Beaumont St., Liberty, Tex. Filed Dec. il, l9l, Ser. No. 161,329 Claims. (Cl. 175-45) This invention relates to drilling apparatus and particularly to apparatus for deeoting lor changing the direction of la hole when drilling same.

This application is a continuation-impart of our prior copending application tiled October `r14, 1957 bearing Serial No. 689,871 vfor Drilling Dellection Method and Apparatus, now abandoned.

In the drilling of oil wells and in the drilling of other holes in :the ground, it often becomes necessary or desirable to drill the hole or well in a direction different than it has been previously drilled. The change in the direction of the hole is known in the field as the deflection of the hole, and under present practice, the deliection of the hole .is accomplished by lirst setting a Whipstocl; in the hole, then lowering a pilot bit `for making an initial pilot hole known as a rat hole at the desired angle of deection from the previously drilled hole, `and thereafter the pilot bit is retracted and `a full size reamer bit is lowered for enlarging the diameter of Ithe deflected hole to substantially the same size as the previously drilled hole.

As can be appreciated, the number of runs or trips for accomplishing the above described sequence of operations involves -a considerable amount ot lost ltime during the raising and lowering operations. Furthermore, the number of mns are 'irequently greatly multiplied because if the hole is to be deflected more than labout: three and one-'half degrees `from the direction of the previously drilled hole, it is necessary to obtain a direction indication of inst leg of the Ade-ileoted hole with a special indicating tool of any one of sevenal known constructions and then the above described sequence of steps is repeated to drill the second leg or the deected hole at an angle of deilection with respect to the iirst leg.

It is an object of this invention to provide a new and improved apparatus for drilling holes at an angle of deflection from a previously drilled hole without requiring the use or" a whipstock for guiding the drill bit at the desired angle of deliection.

Another object of this invention is to provide a new and improved apparatus for drilling holes at an angle of deflection from a previously drilled hole which includes the drilling of a pilot hole or rat hole followed by the roaming of same .in an enlarged diameter without removing `the apparatus from the hole.

An important object oi this invention is to provide a new and improved `apparatus. for drilling holes at an angle of deflection wherein the angle ot deflection is selected prior to lowering 'the :apparatus .into the well or other hole, and wherein such angle may be varied within limits for obtaining diilerent amounts of deflection in the drilled hole.

A further object of this invention is to provide a new md improved apparatus for drilling a well or hole at an angle of deection wherein the direction of such deection may be determined with known dellection indicators, and wherein the apparatus may be manipulated in the well or hole to change the direction of deflection if desired.

A particular object of this invention is to provide a new and improved appara-tus for drilling a well or hole which includes a pilot bit for drilling a pilot or rat hole, and a reamer which is positioned above the pilot bit during the drilling of the pilot hole or rat hole but which is adapted to telescope over the pilot bit for teaming the pilot hole or rat hole to an enlarged size without withdrawing the apparatus from the well.

Still another -object of this invention is to provide a drilling apparatus for drilling deflected holes and the like wherein a pilot bit `and a reamer are provided and wherein means is included for telescoping and extending the pilot bit with respect to the reamer by manipulation 0f the pipe str-ing supporting the apparatus, whereby the apparatus may be manipulated from the ground level t0 select either the pilot bit or the reamer for operation down in the hole.

The preferred embodiment of this invention will be described hereinafter together with other features thereof and additional objects will become evident from such description.

The invention will be more readily understood from a reading of fthe following spccilication and by reference to fthe accompanying drawings forming a part thereof wherein an example of the invention is shown, and wherein:

HG. l is an elevation of the lower pontion of the apparatus of invention to show the pilot bit in the position it assumes in .ya previously drilled hole or well just prior tothe drilling of the deilected hole therebelow;

FIG. 2 is a View, partly in elevation and partly in section, illustrating ,the apparatus of this invention in the position such apparatus assumes after Ithe pilot bit thereof has drilled the pilot hole or rat hole at a deflected angle with respect to Ithe previously drilled hole;

FIG. 3 is a view, partly in elevation and partly in section, illustrating :the apparatus of this invention with the pilot bit retracted for subsequent reaming ot the pilot hole or rat hole with the reamer of the apparatus so as to enlarge the pilot hole or rat hole to the desired diameter;

FIG. 4 is a View, partly in elevation and partly in section, illustrating the central .portion of the apparatus of this invention in detail;

FIG. 5 is la horizontal sectional view taken on line 5 5 of FIG. 4;

FIG. 6 is a horizontal sectional View taken on line 6-6 of FIG. 4; and

:FIG 7 is a view similar to FIG. 2 and shows an additiond modiiication of the present invention.

In lthe drawings, the letter A designates generally the apparatus of nthis invention which is so constructed that it is adapted to be lowered into a previously drilled hole such as a well lbore W (FIGS. l, 2, Iand 3) for initially drilling a pilot hole or rat hole H (FIGS. 2 and 3) and for subsequently teaming the hole H to an enlarged diameter without removing the apparatus A from the well bore W.

e apparatus A includes a housing 1l) at its upper end which is formed with suitable threads lila tor connection with corresponding threads l1 on the lower end of a section of drill pipe P, a portion of which is illustrated in FIGS. 2 and 3. The drill pipe l will be understood to extend to the ground level :or surface of the lwell and it is used for the lowering, raising, and other manipulation of :the apparatus A o this invention, las Will be explained in detail hereinafter. The housing 10 has a lluid passage Yopening ltlb below the threads 11 of the drill pipe P tor establishing fluid communication from the bore of the drill pipe P into the bore or internal opening 10c of the housing 1t?.

The lower end of the housing 1G' has internal threads 19d for receiving external threads 12a formed on the upper portion `of a reamer l2. 'I'he reamer 12 is annular ,and has an internal bore lll2b which is tapered to an upper cylindrical portion which cor-responds in diameter with the internal bore tlc of the housing lil in the prefer-red form ot the invention so that the lower end of the housing y is'open at the rearner l12 as illustrated -in FiG. Zin particular. The reamer -12 is formed with suitable roaming teeth 12C which we best seen in FIG. 3 of the drawings, :and such teeth 12C are utilized for enlarging the diameter ofthe pilot hole or rat hole H, as will be explained hereinafter.

One or more J-slots or :other shaped slots 14, preferably two in number, are for-med in the bore lilo of the `housing. 10. Each of the slots 14 is formed with an upper lateraloiset 14a and a lower lateral off set 14h. The lateral'offset 14b connects the main portion of the slot 14-w-ith :a ventical offset-14C.

A pilot bit or other type of drill bit B is connected with the housing 19 .through a shank assembly S which extends from the bit B upwardly into the interior Yof the housing 10, las will be explained. The shaft or shank assembly S-includes :an upper shaft section S41 and la lower scction S-2 therebelow. The upper section S-l entends from the interior of .the housing 10 and is pivotally connected with the lower :section S42 which is directly connected withthe bitB, as will be explained.

The upper shaft or shank section S-l includes a tubular guide body 2t)v (FIGS. 2 and 4) which has one or more guide pins 21 mounted or formed therewith. There is a pin 21 for eachslot 14 so that each slot 14 hasr a guide pin 21 movable therein in accordance with the shape of the slot 14 and in accordance with the manipulation of the housing 10 relative to the shaft or shank assembly S, as will be evident hereinafter. The guide body has m internal bore 20a therethrough for uid passage, but on the external surface of the body 2u, a plurality of annular grooves 2Gb are provided for receiving 'O-rings 23 which provide a fluid seal between thel external surface of the body 20 and the internal surface of the housing lil. At the upper endl of the body. 20, a recess 20c is providedV for receiving' a support'ring 25 which has a bore 25a therethrough of substantially the-same size asv the bore Zita. has a blade 26 mounted therein which has a short knife edge 27 and. along knife edge 2S formed therewith. Therefore, to changethe position of the blade 26 the ring` is moved relativeY to the body 20. As will beV Vpreferably of the Vtype having a lead plate, maybe used by lowering same down through the drillpipe P and into contact with'the knife edges'Z'Z and 23` so that the plate of'the'indicator member which contacts the edges27 and 2S receives an impression or indication of

Vthe edges

27 and 28. Such indication therefore isY an indication to the operator at the surface or ground level that the bit B is extending in a particular direction with respect to the housing 10S Itwill be understood Y*of course that'other types of indicator'means that the knife Vedges v27 and 28'could be utilized with'the invention without departing from the scope of this inven- OD.

Below the body 20, a tubular adaptor is provided. Such adaptor 35 may be connected in any Vdesired manner tothe bodyj20, but as illustrated internal threads Y 35a on-the adaptor are in Vthreaded engagement with external threadsZld on the lower portion of the body 20.k It will be observed that threads 35a Yand 20d are preferably tool joint threads. The adaptor 35 has an internalbore 35!) which'V is of substantially the same diameter as the bore 20a ofthe body 20. The adaptor` 35 has an annular groove or a plurality of recesses 35C formed for receiving'springs 36 ora` singleV coil Vspring The ring 25' d for a purpose to be hereinafter described. The adaptor 35 has a reduced external diameter at its lower endl which is threaded at 35d and is in threaded engagement with threads 38a on a pivot head 38 so that the adaptor 35 is directly connected to the pivot head 38. It will be recognized that other means for connecting the adaptor 35 to the head 38 could be utilized without departing from the invention. The upper part of the bore 38h of the pivot head 38 is of substantially the same diameter as the main bore portion 35e, but a portion of bore 38h is arcuate and extends inwardly with respect to the bore 38b as shown in the drawings to provide a curved seat 33e. The curved seatV 38e merges with a -downwardly and outwardly inclined inner bore wall 38d. The inclination of the wall 38d is sufficient to permit the position of the pilotY bit B at an angle with respect to the longitudinal axis of the housingV 10. Normally, the bit B will not extend at an angle greater than about three and one-half degrees from the vertical axis.

of the housing 10 and therefore the inclination of the inclined surface 38d ordinarily does not have to be greater than about three and one-half degrees with respect toj the vertical axis of the housing 1G, but it of course could be larger than that if so desired, and conceivably, the

' inclination could even be less than three and one-half degrees under some circumstances.

The lower shank section S 2 includes a tubular member 40 which is formed with ya pivot head or ball 41 at its upper end. The pivot head or ball 41 is preferably integraly with the tubular member 40V and the. bore 40a of the tubular member 49 is preferably of sub-VV stantially the same diameter as the bore 41a through the ball 41. The ball 41Y is maintained in Contact with the the ball 41. Thel pius'45 do'not extend into theV slots.

41b suiciently to prevent a lateral pivotal movement of the ball 41 on the seat 38C. Therefore, the tubular member 40 can move-from the position shown in FIG.l 4

to theposition shown in FIG. 2 without interference' In fact, the tubular member 40` can from the pins 45. move from contact with one side of the wall Y38dfto Y the other side thereof so as to obtain suchlimited pivotal movement, but relative rotation between the member 40 andy the member 33 -is prevented by the pins 45.

1n order to maintain/the tubular member 40 at ai:V

desired angle with respect to the longitudinal` axis of the housing lrand the head 38, a cam ring 46 isslidably mounted on themember 40. Suchcam ring 46 has an upper surface 46a whichV is adapted to contact the lower end 38e ofthe head or member 38.k The surface 46a ofthe cam ring 46 is inclined so that when it is in contact with the surface 38e, the tubular member Y 40 -is caused to be moved or positioned at an angle withV Y respectto the longitudinal axis of the housingrl. This position is seen in FIG. 2 of the drawings. AY spring or resilient means 47 acts Yagainst the lower surface ofY the cam ring 46 to Vmaintain the ring 46 with itsV surface 46a in contact with the surface 38e, but lateral shifting of the ring 46 with respect to the member 38Vis not prevented so that the tubular member 4t) may move to the'position shown in FIG. 4 Vfrom the position show nV Y in FlG.V 2 Vby simply compressing the spring 47 and such action actually occurs during the drilling operation V.with the bit B, as will beV more fully explained. The cam ring 46 is held against rotation with respect to the tubular member 49 by any suitable means such as keys or splines 46]) which engage in coacting keyways or splines 46b in the cam ring 46 so that the cam ring 46 may slide upwardly and downwardly on the member 4l) without turning relative thereto.

The lower end of the tubular member 40 is provided with external threads 40e for receiving a retaining nut 48 for the spring 47 and a lock nut 49 for holding the nut 48 in a desired position to obtain suicient compression of the spring 47 on the cam ring 46 to maintain the ring 46 with its surface 46a in contact with the surface 38e.

The lower shank section S-Z also includes a relatively heavy sleeve 55 which has a central passage 55a therethrough. Such sleeve 55 is in the nature of a drill collar or collars used in drilling and it preferably has internal tool joint threads 5515 at its upper end for threaded engagement with a threaded connector plug 56 (FIGS. 2 and 4) which is threaded onto the lower end of the tubular member 4t?. The plug 56 has a central passage therethrough so that huid communication from the bore 46a of the tubular member 46 is continued on through to the bore 55a of the sleeve or drill collar 55. The lower end of the sleeve or drill collar 55 is formed with internal threads 55C which are adapted to receive the external threads on the bit B. The bit B is formed with water or mud passages 58 so that the mud or other drilling fluid may flow all of the way from the drill pipe P through the apparatus of this invention for discharge at the openings 58 of the bit B to facilitate drilling. The invention is of course not limited to the particular type or shape of the drill bit B illustrated in the drawings because various known types of drill bits may serve in place of the bit B illustrated.

In the use or operation of the apparatus of this invention, the apparatus of this invention is positioned with the shank section S-Z at an angle with respect to the longitudinal axis of the housing 1G as shown in FIG. 2 and then the apparatus is lowered on the drill pipe P until the bit B hits the bottom W as shown in FIG. l of the drawings. The amount of the deiiection of the shank section S-2 with respect to the longitudinal axis of the housing lil is determined by the inclination of the inclined surface 46a on the cam ring 46, within the limits provided by the downwardly and outwardly inclined surface 38d. The cam 46 may of course be changed so as to obtain a dierent angle of deflection of the bit B with respect to the housing l) if so desired, but in most instances, the inclination of the surface ida with respect to the surface 38e will be such that the shank section S-2 will he at approximately three and one-half degrees with respect to the longitudinal axis of the housing l0 so that the hole H which is drilled with the bit B is at approximately three and one-half degrees deflection with respect to the vertical axis of the well bore or hole W which has been previously drilled with another bit. The pins 2l on the body 2G of the upper shank section S-l are positioned in the vertical offset i4c of each of the slots 14 as the apparatus is lowered into the well bore W to the bottom W thereof. Therefore, the shank assembly S is prevented from telescoping within the bore 19C of the housing 1l) during the lowering of the apparatus A of this invention into the well bore W.

When the bit B has reached the lower portion or bottom W' of the well bore W which has previously been drilled with another bit, rotation is imparted to the bit B by a rotation of the drill pipe P from the ground level or surface of the well. Such rotation is in the righthand or clockwise direction as viewed from the top of the apparatus so that the pins 2l remain in the vertical offset portions 14C of the guide slots 14 for transmitting the rotation of the drill pipe P through the housing it) to the shaft or shank assembly S and ultimately to the pilot or drill bit B. As the drilling of the hole H progresses,

the drill bit B remains in its deflected direction which Was initiated by the location of the shank section S-Z at an angle with respect to longitudinal am's of the housing 10 and the shank section S-l tends to move laterally so that for each one-half revolution of the drill pipe P and the apparatus A, the ring 46 moves from the position shown in FIG. 2 to the position shown in FIG. 4. Actually, the tubular member 46 will remain at the inclination shown in FIG. 2 rather than vertical as shown in FIG. 4 but the space between the inclined surface 46a on the cam ring 46 and the lower edge 35e of the head member 38 will occur for each half revolution because the upper portion of the apparatus A will tend to shift laterally relative to the bit B. Therefore, the bit B continues to move in the deflected direction in which it is initially positioned as the bit B is rotated and therefore the bit B cuts the pilot bit hole or rat hole H. The drilling can continue to the depth desired and when the reamer 12 reaches the bottom W of the previously drill hole W, then the reamer 1.2 begins to enlarge or ream out the hole H to an increased diameter. Thus, as the bit B continues to drill the pilot hole, the reamer 12 follows to ream out the hole H to an enlarged diameter.

When it is desired to ream the hole H to the bottom thereof, or substantially the bottom thereof, the apparatus A is lifted sulciently to position the lower part of the drill bit E on the bottom surface W' which remains as a shelf at the upper end of the hole H (FIG. 3). The bit B is thus supported on the bottom W of the previously drilled hole W and the drill pipe P is turned to the left so as to move the housing H relative to the pins 21 for moving the pins 2l into the lateral offset portions l4b and then into the bottom of the slot i4. Thereafter, the housing lll is telescoped over the shank assembly S and the pins 21 are guided in the longitudinal portions of the slots i4 until they reach the upper end thereof. Then, upon applying a right-hand rotation to the housing 19, the pins 2l are positioned in the lateral offsets 14a at the upper ends of `the slots 14.

lt should be noted when the shaft assembly S is telescoped within the bore 1Go of the housing lil, the lower shank section S-Z is caused to straighten out as shown in FIG. 4 of the drawings when the lower shank section S-Z reaches the point of entry into the housing 1t) due to the fact that the cam 4.6 can move downwardly to the position shown in FiG. 4 against the action of the spring 47 when the member 56 engages the tapered bore 12b.

With the bit B substantially retracted as shown in FIG. 3, the reamer l2 is then utilized for fully enlarging the diameter or size of the hole l-l to substantially the same diameter as the previously drilled hole W. The bit B preferably extends below the reamer l-l a slight amount so that if desired, the bit B may be again raised and positioned on the bottom W of the previously drilled hole W for turning the housing it? to the left and raising saine to again locate the pins 2l to the vertical offset 14C for further oiset drilling without requiring the removal of the apparatus A from the previously drilled hole W. For example, after the hole H has been drilled and has been reamed with the reamer 12, the direction of the deilection can be determined from the ground level by the lowering of a known type of deiection direction indicator into contact with the knife edges 27 and Z8. When the direction of the hole H has been determined, and the hole H has been drilled to a sufficient depth and has been reamed with the reamer l2, it may be desirable to make a further deflection in the hole H below the portion of the hole H which has then been drilled and reamed. If such is desired, the bit B may be extended again and the pins 2l may be locked in the vertical o-set portions 14C of the slots 14 and further deflection from the reamed hole H may be obtained. Also, if the deflection direction is not proper, such direction may be changed by beginning the drilling of the additional or new hole at diiferent direction. Therefore, successive legs of deflected hole may be drilled at dilferent angles md different directions with respect to the axis of the previously drilled'hole W and with respect to each leg whichV is thereafter drilled with the pilotV bit B and which is reamed with the reamer 12 so that all of such operations can be conducted without removing the apparatus A of this invention from the hole W. It can therefore be seen that the apparatus of this invention eliminates the many return trips or runs required with conventional whipstock equipment for obtaining the deflection in a wellV bore or hole. Also, it will be evident that the device of this invention eliminates the use of a whipstock for obtaining a dedected hole. Other advantages are also believed evident fromV the foregoing,

Y Y been turned to the left as described inthe above paragraph.

. In order to fully utilize the effect of the drilling iiuid circulated through pipe P, a-hollow shaft or pipe 100 isA connected into the body 20 as shown in HG. 7. The shaft isprovided with a iiuid conducting passage 101 which communicates with bore 20a, and at the upper end of Vshaft 100, there is arranged a piston 102. The piston 102 is providedwith seals 103 for sealably engaging'the well of housing 10 to preventv :duid circulation around the piston. Y v

in the form of the invention shown in lElG 7, the housing 10 will be extended to accommodateV the shaft 100 and piston 102. The upper end of piston 102 is provided with a recess 20c' which is similar to recess 20c in FIG. 4.

When the form of invention shown in FIG. 7 is used, the knife edges 27 and 2S must beV moved to the top of the piston. Thus, recess 20c is provided in the top of piston 102 and is similar to recess Zlc. Also, a support ring 2Slis provided in recess 20c and is shown schematically in FIG. 7. The support ring 25 has a bore there through the same size as bore 101 in'shaft 100. The ring 25 supports the blade 26 which has a short knife edge 27 and a long knife edge 25. The function ofthe blade 26 and edges 27 and 28' is the same as described with regard to the form of the invention shownV in FIGS. 1-6, inclusive. Thering 25 and knife blade 26 may be arranged in the top of piston 102. i

Also, the function, construction, and operation of the tool shown in FIG. 7 is the same as described with regard toV FIGS. 1-6, inclusive, of the drawings; In the form of the invention shown in FlG. 7, the piston 102 Will posi-v tively push or urge the'shaft assembly S from housingy 1? when housing 10 has'been turned to the left so as to cause pins 21 to move down guide slots 14.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various.

changes in the size, shape, and materials as Well as in thef detailsl of thefillustated construction may be made withinv the scope of the appended claims Without departing from the spirit of the invenion. f

What isV claimed is:

1. An apparatus adapted to bemounted on a drill pipe for drilling a hole? at an' angle of deflection comprising:

(a) a tubular housing' having means at its upper end for connection to' a drill pipe,

(b) an annular reamer mounted on the lower end of said housing for rotation therewith,

(c) a pilot bit bodyv slidably mounted in saidhousing,

(d) a pilot bit connected at the lower end of-saidzbody,

' (e) connector means between said housingV and saidv body for slidably connecting said pilot bit body to` said housing for permitting telescopingA and extending of said pilot bitV relative to said rear'ner, Y

(f) said connector means including means for holding said pilot bit body in said housing and holding said pilot bit both in telescoped position andrextendefd position relative to said reamer so that when the pilot bit is' extended it drills a pilot hole and when the pilot bit is telescoped the pilot hole is enlarged by the reamer, Y Y

(g) and means connecting said pilot bit to saidpilot bit body for positioning said pilot bit atan angle with respect to the longitudinal axis of said reamer when said pilot bit is in an extended position.

2. The structure set forth in claim 1 wherein said connector means includes a substantially J-shaped slot in said housing and a pin connected to said pilot bit body and extending slidably in said slot. Y

3. The structure set-forth in claim 1 including a piston connected to the upper end of said pilot bit body and disposed Within said housing in sealing sliding contact therewith so that duid pressure acting on the piston may Vmove said pilot bit longitudinally relative to saidV reamer.

4; The structure set forth in claiml including marking means on the upper end of said pilot body for'marking an impression member lowered into the hole through the drill string to thereby indicate the angularV direction of the pilotV bit and the deilected hole drilled therewith. Y Y

VReferences Citi-:din the iile' of'tln's patent Y UNITED'STATES PATENTS LeBus Aug.y 1, 1961

Claims

1. AN APPARATUS ADAPTED TO BE MOUNTED ON A DRILL PIPE FOR DRILLING A HOLE AT AN ANGLE OF DEFLECTION COMPRISING: (A) A TUBULAR HOUSING HAVING MEANS AT ITS UPPER END FOR CONNECTION TO A DRILL PIPE, (B) AN ANNULAR REAMER MOUNTED ON THE LOWER END OF SAID HOUSING FOR ROTATION THEREWITH, (C) A PILOT BIT BODY SLIDABLY MOUNTED IN SAID HOUSING, (D) A PILOT BIT CONNECTED AT THE LOWER END OF SAID BODY, (E) CONNECTOR MEANS BETWEEN SAID HOUSING AND SAID BODY FOR SLIDABLY CONNECTING SAID PILOT BIT BODY TO SAID HOUSING FOR PERMITTING TELESCOPING AND EXTENDING OF SAID PILOT BIT RELATIVE TO SAID REAMER, (F) SAID CONNECTOR MEANS INCLUDING MEANS FOR HOLDING SAID PILOT BIT BODY IN SAID HOUSING AND HOLDING SAID PILOT BIT BOTH IN TELESCOPED POSITION AND EXTENDED POSITION RELATIVE TO SAID REAMER SO THAT WHEN THE PILOT BIT IS EXTENDED IT DRILLS A PILOT HOLE AND WHEN THE PILOT BIT IS TELESCOPED THE PILOT HOLE IS ENLARGED BY THE REAMER, (G) AND MEANS CONNECTING SAID PILOT BIT TO SAID PILOT BIT BODY FOR POSITIONING SAID PILOT BIT AT AN ANGLE WITH RESPECT TO THE LONGITUDINAL AXIS OF SAID REAMER WHEN SAID PILOT BIT IS IN AN EXTENDED POSITION.