US2128102A - Overshot - Google Patents

Description

Aug. 23, 1938. R. P. SHERMAN OVERSHO? Filed June 22. 1956 Fig. 4

Ralph P. Sherman INVENTOR a Mb W3 M/.5

Patented Aug. 23, 1938 OVERSHOT Ralph P. Sherman, Houston, Tex., asslgnor to Hughes Tool Company, Houston, Tex a corporation oi! Texas Application June 22, 1936, SerialNo. 88,514

8 Claims.

My invention relates to overshots for engagement with devices positioned in the bore of a well. It is adapted particularly to engage tools in the well to withdraw them, where such tools are provided with means to be engaged by said overshot. My invention is not confined to use in such situations, however, as will appear from the description which follows.

It is an object of the invention to provide an overshot which is releasable from the object engaged by it if the object is stuck and cannot be moved. a

I desire to provide, in connection with the gripping means, a frangible tension means which will break under a predetermined strain and. release the tool.

It is a further object of the invention to provide means whereby the tool withdrawn by the overshot may be easily disengaged from the overshot when the tool has been withdrawn from the well.

It is a further object to provide an overshot which is easily engaged with the tool to be withdrawn but which will not release the tool if it is possible to pull the same. The invention also includes the particular structure of the releasing mechanism which will release the tool with a minimum of effort when it has been withdrawn.

In the drawing herewith Fig. 1 is a central longitudinal section through an overshot embodying my invention.

Fig. 2 is a broken longitudinal section showin the releasing device in a position different from' that indicated in Fig. 1.

Fig. 3 is a, transverse section on the plane 3-4 of Fig. l, somewhatenlarged.

Fig. 4 is a similar enlarged transverse section on the plane 44 of Fig. 1.

The body of my overshot includes a tubular barrel or housing I the lower end of which has threaded thereto a cap 2. Said cap has an axial opening 4 and the wall about said opening is tapered upwardly at 3 to provide an outer cam surface which serves to spread the jaws 5 of the gripping devices, as will be later noted. There are fluid conducting openings 6 through the end of said cap.

The inner walls of the housing 'I are recessed to cooperate with the jaws 5 which are mounted on an inverted U-shaped spring I the upper loop of which is engaged about a transverse pin 8 in a supporting block 9 fitting slidably within the housing. Said dogs are secured to the arms of spring I by rivets ID or by equivalent means and their lower ends have inwardly projecting shoulders presented upwardly to engage below the head I2 oi.- a tool in the well. Below said shoulders the inner faces of said dogs are flared downwardly to engage the projection 3 on the cap 2. One of the spring arms has its lower end bent inwardly to form a stop 13 to be engaged by the head l2 and limit the relative downward movement of the overshot over said head l2. The outer faces of the dogs at their lower ends are enlarged to engage the inner wall of the' housing. Above the normal position of the dogs, as seen in Fig. 1, the inner wall of the housing is recessed at M to allow said dogs to move outwardly. The interior is also recessed at l5 below the dogs to also allow separation of the dogs when they are moved downwardly from normal position.

The block 9 upon which the supporting spring is engaged has its upper end formed to receive the lower head It of a tension link l1. Said head I6 is slidable laterally in a slot l8 into an axial position in. said block. The head l6 moves in an undercut recess l9 and is latched in axial position by a ball 20 engaging in a lower recess in the head It. Said ball is held resiliently upwardly by a spring 2| resting upon a removable plug 22 in the block.

The tension link II has a head Ifia at its upper end adapted to be engaged by the lower ends of a pair of dogs 23. Said dogs are hinged at their upper ends to a transverse pin 24, the outer reduced ends 25 of which are movable 111 slots 26 in the wall of the housing. There is a sleeve bushing 21 on the shaft, as will be noted from Fig. 3, upon which the dogs are mounted. A spring 28 on said bushing engages said dogs and tends to move the lower ends outwardly against the inner wall of the housing.

Adjacent the lower ends of the dogs the inner I wall of the housing is tapered inwardly and downwardly at 29 to be contacted by the beveled lower ends of said dogs, and hold them inwardly engaging about the head l6a of the tension link I! and hold the link firmly supported.

The upper end of housing I is reduced in diameter and a locking sleeve 30 is fitted thereon. Above the sleeve is a cap or nipple 3| which closes 4 the end of the housing and has a threaded shank 32 to couple with the operating string which may include a wire cable.

The sleeve 30 has its lower end cut away on opposite sides thus forming two opposite cam surfaces 33 to cooperate to move the pin 24 in the slot 26. The sleeve has a pair of opposite openings 34 therein and a pair of larger openings 35 thereinspaced 90 from the smaller openings.

,A latch bolt 36 is housed within a transverse opening in a block 31 fitting within the upper end ing pin 38. Said bolt is recessed atone end to receive a compression spring 39 which tends to holdsaid bolt 36 radially outwardly to engage within one of the openings 34 and 35 in the sleeve 30. The outer latching end of the bolt has a small diameter 40 toengage the openings 34 and a larger diameter 4| to engage the larger opening 35. It will be seen that, when latched in the smaller opening 34 as shown in Fig. 1, the lower cam surface of the sleeve will hold the pin 24 of the latching mechanism downwardly. When the larger diameter 4i engages in one of the openings 35, the sleeve 30 will permit the upwardmovement of the pin 24 in the slot 26.

When this overshot is employed to remove from within the drill stem a tool, such as a re-. tractible core barrel, for example, the overshot is lowered atthe end of a wire line. When thus lowered the ports are set as shown in Fig. 1.

the knob 12 thereon will pass upwardly through the opening 4 in the overshot and by engaging the lower ends of dogs 5, will move them upwardly into the recess l4 where said dogs will be spread apart and when the knob I2 is in position against the stop I3 the dogs will snap inwardly below the same and an upward pull on the overshot will move the dogs downwardly to locked position, as shown.

An upward pull on the overshot will lift the core barrel.

If the core barrel should be lodged too tightly so that it could not be pulled, the stem of the tension link I! will break, when a certain predetermined tension has been exceeded, and allow the dogs to drop into the recess l where the projection 3 will spread the dogs apart and release the knob II. The overshot may then be withdrawn from the drill pipe.

If the core barrel can be withdrawn the overshot must then be disengaged from the knob H of the barrel. To do this the dogs 5 which hold the knob l2 must be moved down from looking position as seen in Fig. 1. To do this, I unlatch the upper end of the tension link from the holding dogs 23. A rod or tool will be used to shove the bolt 36 inwardly so that sleeve 30 may be rotated through 90 and thus allow the pin 24 to move upwardly in the slot 26. The bolt 36 will then latch in opening 35 as seen in Fig. 2. The tension of spring 28 will tend to urge the dogs outwardly so that, when the dogs have been moved upwardly along the tapered surface 29, they will release the head Hill of the tension link. This upward movement of the link I! is accomplished by shoving the tool and knob I 2 upwardly relative to the overshot; the supporting block 9 being thereby moved to the position shown in Fig. '2. The link I! is thereby released and the block 9 and dogs 5 will drop down so as to release the knob ii. on the core barrel. The overshot could then be reset for further use.

The tension link I! is arranged so that it may be examined to determine whether it has been stretched or cracked. An opening 43 is slottedin the side of the housing I adjacent said link so as to provide a clear view of said link for observation and replacement.

My overshot has the advantage of being easily engaged and disengaged from the tool which is to be removed. Also it is releasable by the breaking of the link under strain too great for the tool to withstand. After the device has been withdrawn, it is quickly released from the core barrel by simply unlatching and rotating the sleeve 30 and then collapsing the overshot toward the core barrel as described.

What I claim as new is:

1. In an overshot, a tubular housing, tool gripping dogs enclosed within the lower end of said housing, means to support said dogs in said housing in position with said dogs latched on said tool, said means being rendered ineii'ective to retain said dogs in latched position in response to a predetermined pulling force applied thereto and wedging means in said housing below said dogs to unlatch said dogs when they are moved from latched position.

2. In an overshot, a tubular housing, tool gripaping dogs enclosed within said housing, said dogs being held together in gripping position by the wall of said housing, said wall being recessed above and below the said gripping position, means to support said dogs in gripping position but allowing a limited upward movement thereof, said supporting means being rendered inefiective to support said dogs in response to a predetermined strain exerted thereon.

3. In an overshot, a tubular housing, tool gripping dogs enclosed within said housing, said dogs being held together in gripping position by the ,wall of said housing, said wall being recessed above and below the said gripping position, means to support said dogs in gripping position, said supporting means being rendered inefiective to support said dogs in response to a predetermined strain exerted thereon.

4. In an overshot, a tubular housing, tool gripping clogs enclosed within said housing, said dogs being held together in gripping position by the wall of said housing, said wall being. recessed above and below the said gripping position, means to support said dogs in gripping position but allowing a limited upward movement thereof, said supporting means being of frangible material adapted to break under a predetermined strain to allow the said dogs to drop downward into releasing position.

5. In an overshot, a tubular housing, tool gripping dogs enclosed within said housing, said dogs being held together in gripping position by the wall of said housing, said wall being recessed above and below the said gripping position, means to support said dogs in gripping position but allowing a limited upward movement thereof, said supporting means being of frangible material adapted to break under a predetermined strain to allow the said dogs to drop downward into releasing position and means to then spread said dogs apart to release the tool.

6. An overshot includinga tubular housing, tool gripping dogs therein, means to support said dogs in tool gripping position, detachable means in said housing to latch said supporting means against movement to tool-releasing position in said housing, means to release said latching means, said latching means operated responsive to an upward thrust on the tool gripping dogs to move to open position.

7. In an overshot, a tubular housing, tool engaging dogs therein, means to support said dogs in tool-engaging position including a frangible link, means to grip and hold the upper end of said link, releasable on the upward movement of said gripping means in said housing, means to prevent the upward movement of said gripping means releasable manually when desired to allow said link and dogs to move downward to disensaid housinl. a pin to which said :laws are congage said dogs from said tool. nected, a sleeve on said houainc adapted tov en- 8. In an overshot, a tubular housing, tool engaze and hold said pin and don: downwardly gaging dogs therein, means to support said dogs when said sleeve is in one position, but adapted in tool-engaging position including a frangible to release said pin and don: when said sleeve is 5 link, means to grip and hold the upper end of rotated to another position.

said link, including a pair of link engaging jaws fitting within a downwardly tapered recess in Bil-PH P. SHERMAN.

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