US2178554A - Well slotter - Google Patents

Description

C. P. BOWIE WELL SLOT-TER Nov. 7, 1939.

Filed Jan. 26, 1938 N H m g 6,

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,|ll|ll lllulllll INVENTOR,

'; BY 73mg. 3021 ATTORNEYS. .2

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w 1 M w Patented Nov. 7, 193a UNiTED sTATEs PATENT OFFICE WELL SLOTTEB,

- Clifford P. Bowie, Berkeley, Calif.

Application Janua y 26, 1938, Serial No. 187,021

.5 Claims.

This invention relates to apparatus for increasing the effective producing area of a drilled well, and constitutes an improvement upon the invention disclosed and claimed in my application Serial No. 142,953, filed May 17, 1937.

More specifically, the invention relates to an apparatus which is capable of being lowered into 'a drilled well, and which can be operated from the surface, to cut slots in the formation into or through which the well has been drilled. The slots are vertical and extend out radially from the well, and there may be as many slots cut, one at a time, as is desired. Each slot greatly increases the exposed area of the formation, from which the fluid may exude. Some wells which, when drilled in the ordinary way as cylindrical holes, produce comparatively little fluid because of certain adverse conditions of underground structure or pressure, can be greatly improved by increasing their effective area and thereby securing greater production. By cutting a plurality of narrow slots in the formation, instead of reaming it out into an enlarged cylindrical chamher, the exposed area is greatly increased, without the danger of destructive caving.

The principal objects of this invention are to provide an apparatus for the purpose described above which is simple and rugged in construction and easy to operate, and in which fiuid pressure means are provided for operating and controlling the feed of' the cutter. Other objects and advantages of the invention will be apparent from the following description, which should be read with the understanding that changes, within the scope of the claims hereto appended, may be made in the form, construction and arrangement of the several parts herein shown and described.

A, preferred embodiment of the invention is illustrated in the accompanying drawing, in which.

Fig. 1 is a vertical section showing the device in position in the well.

Fig. 2 is a vertical section taken at right angles to the plane of Fig. l. c

Fig. 3 is a vertical section, enlarged, of a modified form of fluid pressure operated feed mechanism.

The apparatus requires suitable means for 10- cating or orienting it in the well and holding it securely in position, and suitable driving means for supplying the cutting and feeding power. These holding and driving means may be located either in the well in proximity to the apparatus itself, or at the surface and connected with the apparatus by strings of tubing. The latter arrangement is shown in the drawing, the reference numeral ll indicating a string of tubing to which the apparatus is attached and by which it is lowered or raised and held in position, and I2 indicating a, smaller string of either tubing or rod's which are rotated to provide the power for 5 operating the-cutter. The means at the surface for holding the string II and rotating the string I2 are not own.

The drive tubing l2 has a bevel pinion l3 secured to its'lower end, which meshes with a gear l l4 secured upon a horizontal shaft l5 mounted in the supporting tubing ll. Chains l6 connect said shaft IS with a second horizontal shaft IT, on which is a sprocket l8. Suitable support must be provided for the bevel pinion l3, such as a spider I9 which provides a journal for the lowe end of the tubing 2.

The diameter of the supporting tubing I I is reduced below the shaft ll, said reduced portion forming a shell Ila having a cylinder in 20 which operates a piston 2| and a piston rod 22. Piston rod 20 is prevented from rotating by a guide pin 23 and slot 24. The lower end of said piston rod is enlarged, flattened and slotted, as shown at 25, and carries a horizontal spindle 26 26 upon which an idler sprocket 21 is mounted in the slot of said end 25. The spindle 26 also serves as a pivot for the forked upper end 28 of an arm 29, said arm extending downward and having an idler sprocket 30 mounted in its forked lower 30 end 3|.

An endless, flexible cutter in the form of a chain 32, having spaced projecting teeth 33 operates over the sprockets I8, 21, and 30. Projecting teeth 33 may be of any desired shape, al- 35 though I prefer the bucket type. When the drive tubing I2 is rotated in such a direction as to cause the left hand run of the chain 32 to move upward, the pull of said chain will swing the arm 29 to the left Fig. 1. The teeth 33 will, therefore, come against the left hand side of the well. A hearing plate 34 is provided upon the back of the fork 25, to keep the right hand run of the chain from rubbing against the side of the well.

The pull of the upwardly moving run of the chain 32 is not sumcient to feed the cutter teeth 33 into the wall of the well with the force neces sary to cause them to cut a slot therein, especially in hard formation. Therefore, to provide additional feeding force, fluid under pressure is introduced into cylinder 20, exerting a downward pressure on piston 2| and piston rod 22, swinging the lower end of arm 29 forcibly to the left and causing teeth 33 to dig into the left hand side of the well, cutting a narrow slot into the formation. This cutting continues (until arm 29 reaches a horizontal position) as long as the drive tubing I2 is rotated and fluid pressure is supplied to the cylinder 29; the chain pulling up on the lower sprocket 39 and the downward pressure on piston rod 22 swinging the arm 29 more and more to the left as the cutting progresses. The chain is kept tight by the downward pressure of the fluid in cylinder 29 acting on piston 2| and rod 22. A strong spring 35, interposed between the bottom 36 of the shell I |a and a pin 31 secured to the piston rod 22, holds said rod at the upper limit of its travel, so that the arm 29 normally hangs vertical, as shown in full lines in the drawing. Pressure fluid is supplied to the cylinder 29 through a pipe 36, which may extend to the surface within the tubing II, or which may be connected, by a suitable rotatable coupling not shown. with the tubing I2, in which case said tubing l2 serves as the conduit for the pressure fluid.

When the device .has reached the position shown in broken lines in Fig. 1, the slot in the formation will have the shape shown by the line 39, and that slot will have been completed. Fluid pressure in cylinder 29 is released and spring 35 returns the apparatus to the vertical position shown in full lines. As the pressure in cylinder 29 is released, rotation of the drive tubing l2 may be continued if desired. Spring 35 also serves to hold arm 29 in a vertical position when the machine is being lowered into or raised out of the well or when it is being oriented from one cutting position to another. When one slot has been cut, the machine is rotated to a new position, by turning the tubing II, and a new slot is cut. This process can be repeated as many times as desired, to cut a series of slots radiating outwardly from the well, thereby greatly increasing the exposed surface of the formation.

The spring 35 may be eliminated, and both upward and downward movement of the piston rod 22 and arm 29 effected entirely by fluid pressure, by the apparatus shown in Fig. 3, which takes the place of that portion of Fig. 2 encompassed within the bracket 3. The lower end of the shell ||a supports a cylinder 49 in which is a piston 4| fixed to the upper end of the piston rod 22. The lower end of said cylinder has a closed head 42, and its upper end is formed by a head 43 having apertures 44 and downwardly extending lugs 45 in which are horizontally slidable pins 46 having rounded ends. The piston 4| is .hollow, and has a rounded interior flange 41 at its upper end, which engages the outer ends of the pins 46 as shown.

Two cylinders 49 and 49, of diiferent diameters, are formed in the shell ||a above the head 43 of the cylinder 49. Connected pistons 59 and operate in said cylinders 48 and 49 respectively. A stop lug 52 extends downwardly from the piston 5|, and a central pin 53 extends still further down, through the head 43 and engaging the inner ends of the horizontal pins 46. An eye bolt 54 extends upwardly from the piston 59 through an apertured diaphragm 55, and a spring 56 below said diaphragm normally retains pistons 59 and 5| in their lower positions. A pipe 51 leads from cylinder 49 below piston 5| to the surface. Cylinder 49 may be opened to the interior of the well by any suitable means indicated diagrammatically by pipe 58 and valve 59, and said cylinder 49 may also be supplied with fluid under pressure as indicated by pipe 60 controlled by valve 6|.

Before the apparatus is lowered into the well, the control pistons 59 and 5| are first raised, by inserting a bar into eye-bolt 54 through a slot 62 in shell Ha, thereby raising pin 53 and permitting pins 46 to move inwardly to free the flange 41, Piston 4| and rod 22 are then raised to top position, as shown, and pistons 59 and 5| are allowed to drop, forcing pins 46 outwardly beneath flange 41 to hold piston 4| and rod 22 in elevated position. The parts are now in the position shown, with rod 22 locked in its upper position so that the arm 29 and the cutter chain 32 hang vertically. The device is then lowered into the well.

If the well is empty, i. e., contains no fluid under pressure, the valve 59 is closed and the valve 6| is opened before the apparatus is lowered. Then when the desired depth is reached, fluid under pressure is admitted through the pipe 69 to the cylinder 49 below the piston 4| said pressure being sufficient to support the weight of the piston 4|, rod 22, and arm 29. Fluid under pressure is then also admitted through the pipe 51 to the cylinder 49 below the piston 5|. This pressure raises the piston 5| and its pin 53, freeing the locking pins 46. The apparatus is now in position to begin slotting and as the cutter chain moves and pulls the arm 29 out of line, the pressure in cylinder 49 is decreased and that in cylinder 49 increased, the latter pressure operating above piston-.-.4| through ports 44. Thus piston 4| and rod 22' are forced down to feed the cutter into the formation. When the slot is completed, pressure is increased in cylinder 49 and decreased in cylinder 49, thereby lifting piston 4| and rod 22 until arm 29 and chain 32 hang vertically again, whereupon pressure in cylinder 49 is relieved entirely, allowing piston 5| and pin 53 to descend and lock piston 4| by means of pins 46. Pressure in cylinder 49 can then be relieved and the apparatus pulled up or turned to a new position.

If the well contains fluid under pressure, valve 59 is opened and valve 6| closed before the apparatus is lowered, and pipe 69 need not be connected to the surface. When the proper depth is reached, the well fluid pressure which has entered cylinder 49 through pipe 58, supports piston 4| and rod 22. Fluid under pressure from the surface is admitted through pipe 51 to cylinder 49 to raise piston 5| and release locking pins 46. This pressure in cylinder 49 is then increased above well pressure, to force piston 4| and rod 22 down to efiect feeding of the cutter. Upon completion of the out, pressure in cylinder 49 is reduced slightly below well pressure to permit piston 4| to rise while still holding piston 5| up. When piston 4| is in its top position, pressure in cylinder 49 is reduced further, allowing piston 5| to drop and efiect locking of piston 4| through pins 46. Well pressure also acts on top of piston 59, and therefore opposes pressure in cylinder 49, but as piston 59 is smaller than pistons 5| and 4 pressure in cylinder 49 will raise piston 5| before it afiects piston 4|.

The machine is illustrated as operating below the bottom of the well casing, which is shown at 63. It is entirely possible, however, that with cutters 33 of the proper material, the slots c'uld be cut through the casing. Thus the machine can be operated at any point in the depth of the well.

It will be seen that, when the device is in inoperative position, the cutter chain forms an elongated loop with substantially vertical parallel side runs, and the three supporting sprockets i8, 21' and 3B are substantially in vertical alignment, thus enabling the machine to be lowered into the well. During the cutting movement of the chain, however, said supporting sprockets are shifted out of alignment, so that the side runs of the chain are spread apart into the form of a triangular loop, one of said side runs being forced against the side wall of the well to cut a slot therein.

The initial feeding movement, shifting the three sprockets out of line, is caused by the pull of the'cutter chain. Thereafter the downward fluid pressure on the rod 22 forces thearm 29 to swing still farther to the side, feeding the chain into the formation with greater force. If desired, the axes of the three sprockets can be positioned slightly out of line initially, so that downward pressure on the rod 22 will forcibly shift the arm 29 even before the cutter chain is started.

It is to be noted that no turning or twisting moment is applied to the pivot 26 or to the forks '25 and 28 centered about said pivot. The rod 22 and arm 29 are subjected only to longitudinal compression, and therefore can be much lighter than if they were required to resist bending stresses as well. The tension in the triangular cutter chain balances the compression forces in said rod 22 and arm 29. The reaction of the feeding force is carried by the tension in the chain and the compression in the rod 22 and arm 29 directly to the bearing plate 34 which abuts against the side of the well opposite the out. The pivot 26 is subjected only to shearing stress. This balanced arrangement of forcespermits a lighter structure and greatly reduces friction of the moving parts.

I claim:

1. A well slotter comprising a body capable of being lowered into a well, a movable cutter carried thereby, means for continuously driving said cutter, fluid pressure actuated means for extending and retracting said cutter, said extending and retracting means operating independently of said cutter driving means, locking mechanism for holding said cutter in retracted position, and fluid pressure actuated means for operating said locking mechanism,

2. A well slotter comprising a body capable of being lowered into a well, a flexible endless cutter in the form of a loop, movable supporting members carried by said body over which said cutter runs, means for moving said cutter, and fluid pressure actuated means for moving one of said supporting members relative to another of said supporting members to change the shape of said loop, whereby a portion of said cutter is fed into the formation surrounding the well.

3. A well slotter comprising movably connected body sections, a flexible endless cutter passing around said sections in the form of a vertically elongated loop, said sections being'in substantial alignment when in inoperative position, means for moving said cutter, and fluid pressure actuated means for moving said sections out of alignment to spread the loop of said cutter laterally to cause it to cut into a wall of the well.

4. A well slotter comprising movably connected body sections, a flexible endless cutter carried by said sections in the form of a vertically elongated loop, means for moving said cutter, and fluid pressure actuated means for moving one of said sections laterally to spread the loop ofsaid cutter to cause it to cut into a wall of the well.

5. A well slotter comprising a body capable of being lowered into a well, a vertically movable member mounted therein, fluid pressure actuated means for moving said member, an arm pivotally connected with said member for horizontal swinging movement, a flexible endless cutter, guiding means for said cutter carried by said body and said arm, said cutter causing said arm to swing horizontally when said member is moved vertically, and means for moving said cutter.

CLIFFORD P. BOWIE.

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