US1734468A - Overshot - Google Patents

Description

Nov. 5, 1929. w, s, JONES EI'AL 1,734,468

OVERSHO'I Filed May 15", 1925 2 Sheets-Sheet I 1' INVENTORS,

M'n/ie/d J Jones, and Harold 1/. Baker ATTORNEY Nov. 5, 1929- w. s. .105155 ET AL 1,734,468

OVERSHOT Filed May 15, 1925 2 Sheets-Sheet 2 r IIIIIIIIIIII IYIIIlIlIIIl ATTORNEYS.

Patented Nov. 5, 1929 UNITED ,STATES PATENT OFFICE WINFIELD s. JONES, or BREA, AND HAROLD U. BAKER, or LOS enemas, CALIFORNIA OVERSHOT Application filed May 15,

This invention relates to overshots and has i for an object an improved overshot which may secure tubing at any desired location of such tubing in a well hole.

At the present time it is customary when some break occurs in tubing or when it is desired to lift the tubing for any purpose whatsoever, to attach an overshot to tubing and the tubing plus the overshot is sent down in the well hole and surrounds other tubing concentric therewith already in the well hole. Such other tubing is in coupled form and the overshot slips over such coupling and has dogs adapted to engage under the coupling so thatthe tubing may be raised. The dogs readily slip over' the couplings'when the overshot is moved downwardly, but do not release from the coupling when pulled upwardly, and for this reason difficulties are sometimes encountered which prevent the tubing from being raised due to sanding in or otherwise, with the result that the dogs are either broken off and the tubing with which such overshot is associated sometimes broken at its coupling and the well hole lost, due to a dropping of tools or at best a very expensive fishing job results.

It is an object of our invention to overcome these diiliculties so that if the overshot upon engaging beneath a coupling or collar on tubing has too much strain imposed upon the dogs, as can be readily ascertained by the operator in the derrick above such well hole, the overshot may be readily released from beneath such coupling or collar and moved upwardly for engagement with a further collar, or removed from the well hole altogether, as may seem advisable.

The invention has for further objects the provision of an overshot which is fool-proof, positive in its action, easily handled, has few working parts and which is generally superior with respect to simplicity of construc: tion and inexpensiveness in use and service.

WVith the above and other objects in View, the invention consists in. the novel and useful provision, formation, construction, association and relative arrangement of parts. members and features, all as detailed in cer tain of its embodiments in the accompany- 1925. Serial No. 30,558.

ing drawings, described generally and more particularly pointed out in claims.

In the drawings:

Figure 1 is a fragmentary elevation show ing the overshot in engagement with a tubing collar;

Figure 2 is a view similar to Figure 1 and showing the dog associated with the overshot released from a tubing collar;

Figure 3 is a fragmentary elevation, partly in section and on an enlarged scale from the showing of Figure 1 and showing the dog in engagement with the collar on the tubing; I

Figure 4 is a cross sectional view on an enlarged scale from the showing of Figures 1 and 2 and showing the method of assembling the dogs with relation to the body of the overshot;

Figures 5 and 6 are fragmentary cross sec tional views on an enlarged scale from the showing of Figs. 1 to 4 inclusive, and showing the method whereby the dogs are released from the couplings or collars on tubing, drill pipe or casing in a well hole;

Figure 7 is an elevation of one of the dogs;

Figure 8 is a fragmentary view on an en larged scale from the showing of Figs. 1 to 7 inclusive and showing the crown of the dog in engagement beneath a coupling or collar;

Figure 9 is a fragmentary elevation showing the engagement of the dog beneath the collar;

Figure 10 is a perspective view on a reduced scale of the dog shown in Fig. 7; and,

Figures 11 and 12 are fragmentary sectional views showing the method of associating the dog or dogs with the overshot body.

I Corresponding parts in all the figures are designated by the same reference characters.

Referring with particularity to the drawings, the overshot is designated as an entirety and in one embodiment by A and the same includes a body a sometimes termed a bowl,

pipe or nipple, and dogs 5 of which there may i be one or more carried by such overshot body. As is customary the overshot is associated with tubing,casing or piping ,c, and as has been pointed out, such overshot body as well as the pipe c, is of an internal diameter suflicient to run upon pipe or casing lost in a well hole, such pipe supposedly lost being designated by (Z. The principle of the overshot is well understood. and ordinarily overshots are provided with flat steel springs within the body or bowl, which, when the overshot is run on a casing or drill pipe will slip over the pipe collars when the overshot is moved clownwardly and engage beneath such pipe collars when the overshot is raised. Instead of using ordinary flat spring members for engaging beneath the collars, we have provided dogs Z). The overshot body in the embodiment of the invention shown is transversely slotted as shown at 1, and three of such transverse slots are provided equi-distantly spaced apart within such overshot body, the overshot body being substantially annular, reference being had to Figure 4. These slotted portions are adapted to accommodate the dogs Z).

It is the purpose of the invention to form the dog or dogs 6 in such a manner that an unbalanced driving force is set up when the dog or dogs are engaging beneath the collar and the overshot rotated, which unbalanced force effects a camming of the dog or dogs from beneath the collar. It is a further purpose to form the dogs so that during the camming of such dog or dogs from beneath the collar the dogs have a bearing surface throughout their length so that twist of such dogs resultant upon the camming action is in a large measure overcome.

Only one of the dogs will be described, as the others are similar, as has been pointed out, and each dog b includes an elongated body member 2 provided with a bore 3 adjacent an end 4 thereof, with the opposite end portion 5 beveled downwardly with respect to a surface 6 of such dog and likewise beveled slightly downwardly with respectto a side wall 7 as shown at 8. This construction forms what may be termed a cutting point 9 and a cutting edge 10, and such end opposite the end 4 is designated as the work-engaging end of the dog. The dog gradually increases in transverse thickness from the work-engaging end of the dog to the portion 4 of such dog, as illustrated in Fig. 10, and such dog is likewise formed with a rib or flange 11 directly opposite the side 7. In actual practice the surface 6 of such dog may be termed the work presenting surface as when the dog is assembled with relation to the overshot body, such surface would be adjacent the casing or collar of the casing to be recovered from the well hole, and such work presenting surface 6 is curvedly formed as illustrated in. Fig. 7 at 12 from the end 4 to the work-engaging end of such dog so as to normally form a continuation of the inner curved surface of the overshot body when the dog is approximately completely confined within the slot 1 of such overshot body. See Figs. 11 and 12.

The surface 2 of such dog is par- 1 tially cut away as illustrated at 13 so as to normally approximate a continuation of the curved periphery of the overshot body. Such dog is formed with a notch 14 on the side 7 and opens adjacent the work-presenting surface 6, the purpose of the notch being described later.

The recesses in the body are adapted to con fine the dogs, as has been stated, and the bottom wall or one of the walls surrounding each recess is socketed as shown at 15, it being noted in this particular that the end 4 of each dog is curved so as to fit within such socketed portions 15. The wall adjacent each socket portion is recessed as shown at 16, and received within such recess is a portion of a leaf spring 17 which is secured to the overshot body by any suitable means as shown at 18 with an opposite portion of such leaf spring bent inwardly so as to bear against this surface 2 adjacent the rib 11 of the dog as shown at 18 for the purpose of forcing the same about a pivotal Zone 19 to press the workengaging end of the dog inwardly of the overshot body as illustrated in Figure 3. The annular overshot body is provided with a bore which is a chord of the circle, as shown in 4, 5 and 6, at 20, and a pin 21 is adapted to be passed through such bore and through the bore 3 in the dog so as to hold the dog within the socket portion 15. he overshot body is likewise cut inwardly as shown at 22 and then bored as shown at 23, the wall surrounding the bore being screwthreaded for reception of a screw 24, which screw is adapted to be received in the notched portion 14, as shown in Fig. 12. This method of course limits the inward movement of the dog. It will thus be seen that as a matter of fact the pin 21 is not necessary for the proper working of the dog, for when the dog is socketed the screw 24 by fitting he notch 14 will limit movement of the dog and prevent its displacement from the socket portion 15. Thus the dog is maintained hinged to the body. The outer wall of the overshot body adjacent the slotted portions 1 is slightly recessed as shown at 25 and received in such recess 25 and therecess 16 is a thin metal sheathing 26 conforming in curvature to the periphery of the overshot body and a continuation thereof. The purpose of this sheathing is of course to protect the dog or dogs against dirt and other debris wedging behind the same and preventing their operation. Each dog in the embodiment shown is so mounted with relation to the overshot body that considering the longitudinal axis of such overshot body, a radial line drawn from such axis would practically cut the pin 21 at right angles, and the side of the dog which carries the rib 11 would likewise be at approximate right angles to such pin 21. Taking the dog and its mounting as just de scribed, and assuming that tubing is to be recovered, the overshot body is secured to casing 0 and lowered within the Well hole until the belied or beveled mouth 27 slips over the collar 28 of such tubing to be recovered, it bein noted in this particular that the internal diameter of the overshot body is greater than the external diameter of the collar, and that the overshot body carrying the dog or dogs slips over the periphery of the collar until the dog or dogs under spring urgency are received beneath the collar or at the base portion thereof, as indicated in Figure 1, for instance, at 29. hen this occurs an upward pull of the casing a carrying the overshot will tend to lift the tubing (Z with its collar 28. However, assuming that the well operator in his endeavor to recover a greater length of tubing had passed the overshot over several collars and upon attempting to lift the casing c with the overshot, found that there was danger of stripping the threaded portions where the casing joins such overshot.

With the ordinary type of overshot the chances are that the overshot would either be ruined or a second fishing job would be entailed to recover the overshot. The present invention will allow a releasing of the dogs from beneath the base portion 29 of the collar 28. See Fig. 4 which illustrates three dogs beneath the base and engaging the base of the collar 28. Due to the beveling of the working end of the dogs any pressure imposed thereon will tend to form a line of indentation in the base of such collar 28, as illustrated for instance by dotted lines in Figures 5 and 6 at 80. If the overshot body were rotated in the direction of the arrows in Figs. 5 and 6 the cutting edge 10 of the dog would travel along such indentation 30 and the dog would be released from beneath the base of such collar 28 as illustrated in Fig. 6. This would occur regardless of the indentation, for the reason that there is an unbalanced relation between the forces which act upon the dog; that is to say, in the ordinary overshot provided with spring dogs the pres-- sure of such spring dogs beneath the base portion of the collar is equally distributed, because the working end of each dog is tangent to the periphery of the tubing to be recovered, and the projection of a radial plane from the longitudinal center of such tubing to where it cuts the tangent at right angles would divide the working face of such dog into halves. Thus any tendency to rotate one direction or the other would not permit the dogs to slip from beneath the collarasthe pressure on each side of the radial line cutting the tangent would be equal. In our case, how ever, the force is unbalanced and thewidth or working end of the dog at one side of the radial plane cutting the end of the dog tangent to the periphery of the tubing, is of greater width than the end at the opposite side of such radial plane. In other words,

it is not absolutely essential to cut the dog so that a side thereof forms a continuation of such radial plane where it cuts a tangent, but so long as the width of the dog at one side of the radial plane is greater than the width at the opposite side thereof, this upsetting influence of the dog when the overshot body is turned, will cause such dog to be cammed, as it were, from beneath any collar.

The springs 18 are sutficiently strong to tend to force the dogs inwardly of the overshot body, but not sufficiently strong to overcome the camming action of the dogs upon rotation of the overshot body, and if any dbris should get behind the dog and be lodged between such dog and the sheathing it is intended' that the sheathing will burst and allow such debris to escape from behind such dog when the overshot body is turned to cam the dog from beneath the collar.

It is obvious that various changes and modifications may be made in practicing the in vention, in departure from the particular showing, without departing from the true spirit of the invention.

Having thus disclosed our invention, we claim and desire to secure by Letters Patent:

1. An overshot for well tubing including an annular bowl having recesses therein, and coupling engaging dogs in said recesses, said dogs each comprising an elongated body rockably supported at its lower end in the bottom of a recess, and said body being formed to provide a greater projection at one edge from the innerface of the bowl than at the other edge and progressively increasing in thickness from the upper end toward the bottom end to provide a cam face for engaging the tubing to be lifted.

2. An overshot for well tubing including an annular bowl having recesses therein, and coupling engaging dogs in, said recesses, said dogs each comprising an elongated body-haw ing a transverse bore, a pin for entering said bore and constituting an axis for pivotally mounting the dog at its lower en d in the body, and-the body of the dog progressively increasing in thickness from the upper end toward the bottom end and having its tube engaging face transversely curved whereby the body has a greater projection from the axis of the bore at one edge than at the other.

3. An overshot for well tubing including an annular bowl having recesses therein, and coupling engaging dogs in said recesses, said dogs each comprising an elongated body having a transverse bore, a pin for entering said bore and constituting an axis for pivotally mounting the dog at its lower end in the body, the upper end of the dog being beveled and lower at one edge than at the other, the said body progressively increasing in thickness from the upper end toward the bottom end and having its tube engaging face transversely curved whereby the body has a greater projection from the axis of the bore at one edge than at the other.

a. An overshot for well tubing including an annular bowl formed with recesses therein, one of the long sides of each recess being formed radial to the aXis of the bowl and the other side of the recess being parallel to said radially formed side, a coupling engaging dog pivotally mounted in each of said recesses and having a cam face for engaging with the tub ing to be lifted.

5. An overshot for well tubing including an annular bowl having recesses therein, one of the long sides of each recess being radial to the axis of the bowl, and a coupling engaging dog pivotally supported at its lower end in each of said recesses and comprising an elongated body progressively increasing in thickness from its upper end toward its lower end having its tube engaging face transversely curved whereby the body has a greater projection from the pivot axis of the dog at one edge of the body than at the other.

6. An overshot for well tubing including 2 an annular bowl having recesses therein, one of the long walls of said recesses being formed radial to the axis of the bowl and the opposite wall being parallel to said radially formed wall, a socket member fitted in the bottom of each of the recesses, and a coupling engaging dog arranged in each of said recesses, and each dog comprising an elongated body having a rounded bottom edge for fitting in said socket member of the recess and having an inclined beveled upper edge and progressively inoreasim in thickness from the top end toward the bottom end and the said bottom end having a transverse bore therein, a pivot pin passing through the wall of the bowl and through said bore, and the tubing engaging face of said elongated body being transversely curved, means for limiting the inward movement-of said dog, and a spring engaging the rear face of the body of the dog for urging the same inwardly.

7. An overshot for well tubing including an annular bowl having recesses therein, each of said recesses having parallel walls, one of said walls lying in a plane perpendicular to G9 the inner and outer peripheries of the bowl and parallel to the longitudinal aXis of the bowl, and coupling engaging dogs pivotally mounted in said recesses.

In testimony whereof, We have signed our names to this specification.

/VINFIELD S. JONES. HAROLD U. BAKER.

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