US3421590A - Apparatus for deflecting a borehole - Google Patents

Description

1969 R. .1. SLCLAPPISON 3,421,590

APPARATUS FOR DEFLECTING A BOREHOLE Fiied Nov. 26. 1965 Sheet of 2 Jan. 14, 1969 R.'J. S.CLAPP1SON 3,421,590

APPARATUS FOR DEFLECTING A BOREHOLE Sheet Filed Nov. 26, 1965 United States Patent,

3 Claims ABSTRACT OF THE DISCLOSURE An apparatus for deflecting a bore hole wherein a deflecting wedge assembly is attached to the lower end of a drill rod and locked in position relative to the bottom of the bore hole so that when the bore hole is drilled past the deflecting wedge, the bore hole is deflected relative to the main bore hole by the deflecting wedge.

This invention relates to a drilling method and apparatus and more particularly to a method of and apparatus for deflecting bore holes.

It is often found that a bore hole needs to be deflected as it becomes deeper as, for some reason, the bit tends to move or be moved away from its normal course.

Previously, there have been several methods of deflecting bore holes, all of which use a wedging process of one type or another. These wedging processes necessitated a wedge being positioned within the bore hole and then the bit to be moved down over the wedge which deflects the bit.

These previous processes have been unsatisfactory for three major reasons. The first of these was that the wedge was either left down in the bore hole after each wedging, and as it is not unusual for eight or ten or more wedges to be used in a single hole and as wedges themselves are expensive, the total cost was high or alternatively, wedges have been proposed which could be removed from the bore hole on the completion of the hole but these have often caused difhculty both in the bore hoe and during recovery. The second main disadvantage of the previous wedging systems was in the cost of labor involved in that a single wedging took a relatively lOng time, and, as each deflection is through only a very slight angle of the order of a half to 2 degrees, if a large correction is required the cost of labor involved in the wedging was very high.

Further, with previous wedging systems it has only been possible to deflect the bore hole by wedges every 25 feet as a minimum and under some conditions the natural deflection of the hole over this distance will be greater than the correction that can be a plied by the wedging. Thus the bore hole still tended to move away from the correction direction even though maximum wedging was achieved.

It is an object of the invention to provide a method of deflecting a bore hole which is cheaper than methods previously used both in capital outlay and in the costs of labor involved but which, at the same time, is more eflicient than previously known methods.

The method of the present invention includes attaching a deflecting wedge assembly to the lower end of the drill rods, locking this deflecting wedge assembly in position relative to the bottom of the bore hole, drilling a smaller diameter bore hole past the deflecting wedge, which smaller diameter bore hole is thereby deflected relative to the main bore hole, and removing the deflecting Wedge assembly from the hole before drilling is continued.

Preferably, the deflecting wedge is carried in a casing which has an internal diameter larger than the external diameter of the bit, which casing is associated With the Patented Jan. 14, 1969 'ice lower end of the drill rod so that the casing is caused to move, at least upwardly, with the drill rod.

The invention may also include a further step of reaming said deflected bore hole out to standard size which comprises positioning a pilot in the deflected bore hole, reaming the sides of the original bore hole thus causing the pilot to move downwardly into the deflected hole, moving the reaming bit over said pilot when the pilot reaches the bottom of the deflected hole to thereby ream the deflected hole out to the standard size.

The invention also includes the provision of a deflecting wedge assembly comprising a housing open along one side and adapted to be fitted to the drill rod and retain the drilling bit therein, a deflecting wedge connected to the housing opposite the open side and a locking wedge fitted to the back of the housing to cause wedging in the bore hole. Preferably, the housing is connected to the drill rod by means of a shear pin so that it can be lowered in the bore hole in its correct orientation. The locking wedge is preferably connected to the deflecting wedge by means of a shear pin so that there can be no movement between the locking wedge and the housing while the housing is being lowered to the bottom of the hole. The connection between the drill rod and the housing is such that the rod can move downwardly relative to the housing after the shear pin is broken, but on upward movemerit of the rod the housing is also withdrawn.

The invention also includes a reamer comprising a barrel having fitted to its lower end a drilling bit and a reamer and having a pilot extending downwardly through the barrel. Preferably, the pilot is connected to the barrel or reamer by means of a shear pin so that the pilot is adapted to rotate with the reamer until its lower end reaches the bottom of a bore hole at which point the shear pin is broken and the reamer and barrel may then move downwardly over the pilot.

In order that the invention may be more readily understood and put into practice reference will be made to the accompanying drawings which illustrate a wedging assembly, a reaming assembly, and, indirectly, the method of the invention. In these drawings:

FIGURES 1 and 2 together show the wedging apparatus when positioned in the bottom of a bore hole;

FIGURE 3 shows the bit passing the wedge and deflecting the bore hole;

FIGURE 4 shows the method of removing the wedging assembly from the hole;

FIGURE 5 is a section along the line 55 of FIG- URE l;

FIGURES 6 and 7 show the reaming assembly half way through the reaming operation; and

FIGURE 8 shows the reaming assembly at the end of its movement.

The deflection wedge assembly 1 is formed about a housing 2 which is a length of standard casing for the hole being drilled. In a preferred form the housing is made from a 10 foot length of such casing. One side of this housing is cut away substantially throughout its length, the cut away portion 3 increasing from the upper to the lower end of the housing so that adjacent the upper end the cut away portion is relatively small and near the lower end the cut away portion comprises more than half of the housing. Fitted within the housing is the deflecting wedge 4 which is indicated by a dotted line in FIGURE 2 and which is narrower adjacent its upper end and wider adjacent its lower end, the wedge preferably having a flat face 5 and a taper of approximately 1 /2". This taper is not critical and may, if required, be as little as half a degree or it may be slightly greater than 1 /2 This wedge 4 is so positioned within the housing with its flat face 5 being directed towards the cut away portion 3 of the housing.

The wedge is connected to the casing in any desired way in practice, it has been successfully rivetted to the casing. The length and taper of the deflecting wedge is such that the deflection obtained is not more than half the diameter of the original hole, as will be understood more clearly hereafter.

At the lower end of the housing 2 the side of the housing away from the cut away portion is also cut away to form a ramp 6 which operation necessitates the cutting away of a portion of the deflecting wedge 4.

A locking wedge 7 is attached to this ramp 6 and runs on a retaining slide not illustrated. The retaining slide is constructed so that the locking Wedge cannot become detached from the housing. The angles of the ramp 6 and the locking wedge 7 being such that the back 8 of the locking wedge lies parallel to the axis of the housing and, as it moves relatively upwardly along the ramp its back 8 moves transversely relative to the axis of the housing. The locking wedge 7 is retained in a position such that it does not extend beyond the continuation of the outer wall of the housing 2 by a shear pin 9 which passes through the locking wedge and through the housing and the deflecting wedge 4.

Positioned within the housing 2 is a core barrel 10 and bit 11 assembly, which barrel and bit are connectable to the main drill rod 12 and are positioned within the housing 2 through the cut away portion of the housing. The bit 11 is of a size smaller than the size of the bore hole and so can be received within the housing.

The upper end of the housing is provided with an internal collar 13 which is of diameter smaller than that of the core barrel 10 and bit assembly 11 but of a larger internal diameter than the external diameter of the normal drill rod 12 so that on upward movement of the normal drill rod 13 the rod and bit assembly within the housing abutting the underside of this collar 13 will cause the housing to be moved upwardly as can be seen from FIG. 4.

In the practical arrangement illustrated, the bit 11 is a bull-nosed bit and it is followed by a reamer 14 of known t e.

l itted through the housing 2 and the barrel 10 in the housing is a shear pin 15 which prevents relative movement between the bit and the housing while it remains intact. This shear pin 15 is adapted to take a higher shear before fracture than is the shear pin 9, previously mentioned, which passes through the locking wedge 4.

In use, the assembly is connected and lowered into the bore hole with the locking wedge 7 being positioned against the wall of the bore opposite to that at which the bore is to be deflected. The assembly may be lowered and maintained in this orientation by using orienting clamps or any other standard method. When the locking wedge rests on the bottom of the bore hole, pressure from the drill tends to move the housing 2 downwardly thus breaking the shear pin 9 and moving the housing downwardly relative to the locking wedge until the assembly is firmly wedged in the bottom of the bore hole with the rear face 8 of the locking wedge bearing against the side of the bore hole and the ramp 6 bearing against the opposite face of the wedge. The position assumed can be seen in FIG. 3.

Continued pressure causes the shear pin 15 holding the barrel 10 in the housing to break thus freeing the barrel and bit. The bit is then lowered to the upper end of the deflecting wedge 4 and drilling is commenced, the deflecting wedge causing the bit to move outwardly deflecting the bore hole. This deflection can be seen from FIG. 3.

At the lower end of the original bore hole the deflection may be as much as half a diameter of the original bore hole and at this point drilling is continued until the deflected hole is some distance past the bottom of the original hole, and because of the use of the smaller bit the deflected hole being of the next size smaller than the original hole. It can therefore be seen at this point that there has been provided a deflected hole, the direction of deflection of which is obtained by positioning the locking wedge correctly and the deflected hole being smaller in diameter than the original hole. The form of the deflection hole can be seen from FIG. 7.

In order to remove the assembly the drill rods 12 are lifted upwardly which causes the core barrel 10 within the housing to contact the underside of the collar 13 of the housing and thus to commence to lift the housing upwardly. The locking wedge 7 does not move until the housing is moved sufliciently for the lower limit of movement of the locking wedge to be reached at which time it is also moved upwardly. The whole assembly is then removed from the bore hole without the deflecting wedge remaining in position as has previously been the case.

The reamer, illustrated in FIGS. 6 to 8, comprises a barrel 16 having on its lower end a matching 'piece 17 to the forward end of Which is connected the standard reamer shell 18 to the forward end of which is connected a reaming step faced or other suitable bit 19. To the rearward end of the matching piece is connected a collar 20 through which passes a pilot stem 21 which passes through the center of the step faced bit and has a substantially conical pilot 22 at its lower end. The pilot 22 has a diameter equal to that of the deflected bore hole previously described. The end of the pilot stem positioned within the barrel is provided with a head or piston 23 to control the movement of the pilot relative to the barrel, the head or piston being provided with waterways 24 therein to permit lubrication of the bit and reamer. Through the collar 20 of the matching piece 17 and through the pilot stem 21 is passed a shear pin 25 which maintains the pilot in position relative to the barrel reamer and bit. Preferably, the pilot in this normal condition extends some 5 feet from the forward end of the step faced bit.

The rearward end of the barrel is connected to the drill rod 12 and water source as is standard in the art.

In use, the pilot 21 and reaming assembly are moved down the hole and as the pilot enters the deflected hole 27 reaming is started and the side of the original hole 27 is opened out to above standard size by reaming on one side thereof. This process carries on until the bit 19 is about to enter the deflected hole 27 by which time the pilot is firmly located within the deflected hole as illustrated and this time its pilot 22 is adjacent the bottom of the deflected hole 27.

As can be seen at this time the total diameter of the bore can be half a diameter larger than the original diameter but because the pilot 22 is of substantially the same size as the deflected hole 27 it has guided the reamer assembly 18, 19 throughout its movement along the axis of the deflected hole.

When the pilot 22 reaches the bottom of the deflected hole pressure by the drill causes the shear pin 25 to break, thus permitting rotation of the reamer assembly relative to the pilot stem 21 and thus the deflected hole can be reamed out to size, the reamer and bit moving downwardly over the pilot stem until reaming is stopped before the bit starts to contact the rear of the pilot, this condition being illustrated in FIG. 8. T 0 stop movement of the bit a stop member 28 is provided in the barrel which cooperates with the head or piston 23 the pilot stem when the barrel has moved a suflicient distance over the pilot stem. At this point the drill rod 12 may be moved upwardly and the barrel 16 moves relative to the pilot stem until the rear face of the head 23 of the pilot stem 21 contacts the rearwardly directed portion 20 of the matching piece at which time the pilot stem is lifted out of the bore hole.

When the reaming assembly has been removed a core run is made with a standard barrel, usually a 5 feet standard barrel.

If necessary at this stage a further wedging operation can be done with the locking wedge now being positioned in the lower end of the deflected hole. It can be seen that wedging can be almost continuous using the apparatus and the method of the present invention and in fact, wedging can be done every 5 to feet if necessary.

Previously, it has not been possible at distances much closer than 25 feet which often meant that the natural deflection of the bore hole was greater than could be corrected by wedging.

Further, it can be seen that the wedging process described herein is relatively fast in that the drill rods only have to be inserted and removed twice to complete a full wedging and reaming operation thus speeding process greatly. In fact, using the method of the invention it is possible to carry out two complete wedging operations in three shifts whereas previously it has been difficult to complete a single wedging operation in under five shifts. The invention thus greatly lessens the labor cost involved in drilling if a larger number of wedgings is necessary. The method of the present invention is limited to deflections from the bottom of a bore hole but should for any reason a deflection be required at a higher level it is quite possible to plug the portion of the hole and from this then cause deflection as required.

I claim:

1. A deflecting wedge assembly comprising a housing open along one side; a deflecting wedge mounted within the housing adjacent the lower end thereof and opposite the open side; means to lock the housing at the bottom of a bore hole; a core barrel disposed within the housing, said core barrel including means on its upper end for connection to a drill rod and means on its lower end for receiving a bit; shear means connecting said core barrel to the housing to prevent movement of the barrel relative to the housing until after a predetermined shear force is applied thereto; and an internal collar provided on said housing adjacent its upper end, the diameter of the collar being sufficient to permit the drill rod to pass therethrough but insufiicient to permit passage of the core barrel.

2. An assembly according to claim 1 in which said means to lock the housing comprises a ramp formed on the housing, a locking wedge movably mounted on said ramp, interacting members on said locking wedge and ramp permitting relative axial movement therebetween from a point at which the locking wedge is within the circumference of the housing to a point at which it extends therebeyond to lock the housing.

3. An assembly according to claim 2, wherein the locking wedge normally extends below the lower end of the housing, and further comprising means to retain the wedge from moving relative to the housing to a locking position until a predetermined shear force is applied thereto.

References Cited UNITED STATES PATENTS 2,716,540 8/1955 McCune 175-61 X 2,950,900 8/1960 Wynes l61 X 3,116,799 1/1964 Lemons 61 3,194,327 7/1965 Smithson 17561 3,285,349 11/1966 Brandon 175-61 X 1,638,032 7/1927 Abbott 17580 X 2,207,920 7/1940 Hughes 17582 X 2,334,746 11/1943 Brantly 17582 X 2,688,463 9/1954 Bettes 175-80 NILE C. BYERS, JR., Primary Examiner.

Images