US1733452A - Underreamer - Google Patents

Description

Oct. 29, 1929. 1. w. DOODY 1,733,452

UNDER-REAMER Filed Dec. 13. 1926 imn T Patented Oct. 29, 1929 UNITED STATES ATENT OFFICE UNDERREAIL EB Application filed December 13, 1828.

This invention relates to underreamers of the type utilized with the standard method of drilling artesian and oil wells to enlarge the bore and permit the lowering of the well casing.

This invention relates particularly to the incorporation of important improvements in underreamers of the bowl type. In a bowl type of underreamer. the reaming cutters are carried by an expanding mechanism which is mounted Within the tubular or bowl body.

Underreamers of this type are subjected during the reaming operation to severe upward and lateral thrust strains which frequently result in the breaking off of the cutter heads and the loss of the same in the well. The shear of these cutter heads because of these strains is particularly due to the fact that when the cutters are expanded to the ream- 0 ing position, the same are diverted outwardly and downwardly from the reaming body and the blow struck by the tool has a tendency to spread or split the cutters apart during some periods of operation of the tool. During other periods of operation of the tool, particularly when the hole is approximately the diameter of the cutters, there is a tendency to crush the cutters together to shear the same oil' in this direction.

An important object of this invention is to provide means on the cutter heads at the bottom of the reamer body for taking up the upward and lateral thrusts imparted to the cutter heads during the reaming operation. Another object of this invention is to provide an underreamer of the bowl type having reamingcutters mounted below the body so as to directly impartall end thrust to the body and in which tubular body there is provided a spreader block which is set within the body for expanding the cutters outwardly to the reaming position.

Another object of this invention is to provide an underreamer of the bowl or tubular body type having an expanding reamer cutter mechanism mounted within the body and means offset relative to the axis of the body for holding the expanding means.

Another object of this invention is to provide an underreamer of the bowl type and Serial No. 154,465.

an expanding reamer cutter mechanism mounted within the body and carrying cutter heads having formed on their upper surface arcuate recesses adapted to fit the end of the body of the underreamer to provide thrust bearings to take up the end and lateral thrusts imparted to the body.

Another object of this invention is to provide an underreamer of the bowl or tubular body type having an expandible cutter unit including a spring adapted to yieldably urge the cutters to the expanded or reaming position and which expansion means are so constructed as to enable the assembling of the same to place upon the spring tension before the unit is assembled within the tubular body.

Other objects and advantages of this invention will be apparent from the following detailed description.

A preferred embodiment thereof is illustrated in the accompanying drawings, in which drawings:

Figure 1 is a sectional side elevation of an underreamer embodying this invention illustrating the same as in position with the cutters held in a non-reaming position and as passing through a section of the casing.

Figure 2 is a tragmental sectional elevation of the underreamer illustrating the cutters in the expanded position.

Figure 3 is an end sectional view taken substantially on the line 33 of Figure 1.

Figure 4 is an end elevation.

In the preferred embodimentof this invention illustrated in the accompanying draw ings, 1 illustrates a well hole in which a casing 2 is being lowered. The well hole 1 has been drilled to a diameter substantially as illustrated at 3 and in order to lower the well casing 2, it is necessary to ream out the hole 1 to a diameter larger than the exterior diameter of the casing 2.

It is customary in the art to employ an un derreanoer tor reaming outthe hole 1 to a diameter sutiicicnt to permit the casing 2 to be lowered in the well and it is for this use that the tool which is really an expandible drill derives the name underreamer.

The underreamer embodying this invention comprises a tubular body 4 having formed at its upper end a tool joint 5 by means of which the same is secured to a cable or the like so as to permit the same to be reciprocated in the hole. The body 4 has an axial chamber 6 formed therein, in which an expandible cutter unit 7 is mounted. The expandible cutter unit 7 supports within the tubular body 4 cutter heads 8 below the lower end 9 of the body 4.

The cutters 8 may be of any suitable or desirable construction as is well understood in the art and are provided near their upper surface 10 with arcuate recesses 11 which lit the lower end 9 of the body 4. The annular flange provided around the arcuate recesses 11 provides on its inner surface 12 a bearing surface which acts to prevent the collapsing of the cutters 8 together when the cutters are expanded to the reaming position. The lower surface 13 of the arcuate recesses 11 provide end thrust bearings against which the end 9 of the body 4 is engaged during the reaming operation so that all of the end thrust imparted to the cutters 8 during the operation of the tool is imparted directly upward to the reamer body 4 and these end thrust bearing surfaces are provided at a point close to the point of engagement of the cutters 8 with the ground so that the leverage incident to the operation of the cutters to produce lateral thrust in the cutter heads 8 is reduced to a minimum. Mounted within the chamber 14, formed at the lower end of the body and at substantially the lowest extent thereof, is an expanding block 15 which provides expanding bearing surfaces 16 which are tapered complementary to the expanding bearing surfaces 19 formed on the inner surface of the cutters 8, so that when the cutters 8 are both upward from the position illustrated in Figure 1 to the position illustrated in Figure 2, the bearing surfaces 19 ride along the bearing surfaces 16 and cause the cutter heads 8 to be expanded outwardly. The bearing surfaces 16 are positioned entirely below the lower end 9 of the body 4 and the bearing surfaces 19 are so positioned that the cutters 8 are entirely expanded outwardly before the lower end 9 of the body passes into the arcuate recesses 11.

The expanding unit mounted in the tubular body 4 is preferably of the following construction and comprises a T-shaped stem 20, the prongs 21 of which are releasably fitted within recesses 22 formed in the shanks 23 of thecutter 8. The T-shaped stem extends upwardly into the axial chamber 6 and a spring 24 is mounted thereon. A head 25 preferably comprising a hexagonal nut is screw-threaded to the upper end of the stem 20 and a bearing sleeve 26 is mounted on the stem 20 between the head 25 and T prongs 21. The bearing sleeve 26 is slidably mounted on the stem 20 and is engaged by one end of the spring 24. The opposite end of the spring 24 engages the head 25. Formed on the T-shaped stem 20 below the sliding sleeve 26 is a pair of outwardly extending lugs or trunnions 27. In assembling the expandible unit, the prongs 21 of the T-shaped stem 20 are first inserted within the recesses 22 of the cutters 8 and the sleeve 26 is then mounted on the stem 20. The spring 24 is then mounted on the spring 20 and the nut 25 is screw,- threaded at the upper end of the stem until the tension is imparted to the spring 24, the trunnions 27 holding the slidable sleeve 26. The expandible unit is then inserted in the body and an expanding wedge is passed through a pair of alined slots 28 formed in the body 4 engaging the lower edge of the slidable sleeve 26, forcing'the same upward. The wedge (not shown) is pushed through the slots 28 and displaced by a key 29. Formed at the edge of the slots 28, on the outer surface of the body 4 are recesses through which cotter pins 30 are inserted into the ends of the key 29 to hold the same in position.

In order to permit the expanding mechanism to expand the cutters quickly when the underreamer is in the well, there is provided in the body 4 a port 31 through which the liquid mud or water which is within the body of the reamer may be expelled as the cutters are expanded into the body.

Inorder to permit lowering of the underreamer into the well, the cutters 8 are moved to the non-reaming position as illustrated in Figure 1, against the tension of the spring 24, and are tied in this position by means of a wire or bale 32 and the underreamer is lowered into the well to the bottom thereof and is then lifted and dropped to break the bale 32 to permit the cutters 8 to be expanded by the spring 24 to the position shown in Figure 2.

The key 29 passes through the body 4 and under the slidable sleeve 26 in off-center position, as illustrated in Figure 2, so as to permit the same to pass the stem 20.

Any suitable or desirable means may be provided for holding the expanding block 15 in position at the lower end of the body so that the same may be removable to permit replacement when worn,-which means preferably comprises a bolt 33 which is passed through the lower end of the body and through a central bore formed in the block 15. The head of the bolt 33 and the nut thereof may be counter-sunk within the body, as illustrated in Figure 4.

Having fully described a preferred embodiment of my invention, it is to be understood that I do not wish to be limited to the exact details herein set forth, which may obviously be varied without departing from the spirit of my invention as set forth in the appended claims.

I claim:

1. In an underreamer, the combination with a tubular body, a pair of reamer cutters having shanks adapted to extend into an axial chamber formed in the body, a spreader block removably mounted intermediate the 5 shanks in the chamber, cutter head formed on the shanks below the body, the cutter heads having arcuate pockets formed in their upper ends adapted to closely fit the periphery of the body, and means for yieldingly holding the cutters in expanded position.

2. In an underreamer, the combination With a tubular body, a pair of reamer cutters having shanks adapted to extend into an axial chamber formed in the body, a spreader block removably mounted intermediate the shanks in the chamber, cutter heads formed on the shanks below the body, the cutter heads having arcuate pockets formed in their upper ends adapted to fit the end of the body, means for yieldably holding the cutters in expanded position, and means adapted to be inserted through the bore formed in the body in 01fset position for holding the latter said means. 3. In an underreamer, the combination of a tubular body, a pair of reamer cutters having shanks adapted to extend into an axial chamber formed in the body, a T-shaped stem mounted Within the body and releasably secured to the cutters, means for releasably 0 securing the T-shapecl stem in the body, a spring mounted on the stem, a sleeve slidably mounted on the stem and engaging one end of the spring, a head removably secured to the body and engaging the other end of the as spring, trunnions formed on the stem and acting as limit stops to hold the slidably mounted sleeve, cutter heads having arcuate recesses formed therein into Which the end of the tubular body is fitted when the cutters are expanded to provide end and lateral thrust bearings and a spreader block mounted in said chamber intermediate said cutters when the cutters are expanded to form with the cutters and body a straight line of metal in contact from: one cutter through to the next cutter.

Signed at Los Angeles, California, this 6 day of Dec, 1926.

JOHN W. DOODY.

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