US2093794A - Jar device - Google Patents

Description

A. S. BAPTIE sept. 21, 1937.

JAR DEVICE Filed March 22, 1937 [lll FIG'.

FIG.

Patented Sept. 2l, 1937 UNITED STATES PATENT oFFlcE un nsvlcs Albert S. Baptie, Bakenileld, Calif., a-ignor to Shell Development Company, San Francisco. Calif., a corporation oi Delaware Application March 22, 1937, Serial No. 182,293.

Clalms.

This invention'pertains to a jarring tool for use in connection with devices or instruments lowered into boreholes and operated therein by a well at the end oi a drill string, tubing string,

or sucker rod string, although they are most commonly supported by a ilexible cable made of wire, wire. and rubber, fabric, hemp, etc., comprising ll an insulated electrical conductor.

It frequently happens that these devices become stuck or jammed in the borehole, and that attempts to disengage them by exerting a pull on the cable cause the latter to break. Long and N costly ilshing operations must then be resorted to in order to retrieve the instrument, and ii they fail the instrument may become entirely lost in the hole.

It is the object of this invention to provide a jarring or knocking tool for electrical devices whereby said devices could be released from engagement with obstructions within boreholes without the necessity of exerting an excessive pull on the supporting cable. 80 It is a further object of this invention to provide a jar which would permit electric current to be supplied to said electrical devices during the time when the jar is operated.

It is another object of this invention to pro- 35 vide a jar constructed so that the electrical conductor passing therethrough is not subjected to any appreciable tension or compression stresses during the operation of the jar.

These and other objects and features of the 4 invention will appear more clearly from the following description taken with reference tothe attached drawing in which Fig. 1 is an elevation view, partly in cross section, oi' a jar forming one embodiment of the present invention.

Fig. 2 is a transverse cross-sectional view taken valong line A-A of Fig. 1.

Fig. 3 is a cross-sectional elevation view of va. jar forming another embodiment oi the present invention.

Fig. 4 is a transverse cross-sectional view taken along line B-B of Fig. 2.

Referring to Pig. 1, an electrical conductor I is shown within the strands o! a cable 2 sup- 55 porting the jar and any electrically operated desion stress.

vice attached thereto. A cable socket i pro- ,vided with an axial bore is amxed to the end oi the cable 2 by introducing the end of the cable into said bore and clamping it there by a suitable means, !or example a molten friction metal 5 such as babbitt, as shown at l. The cable socket 5 may be provided with external serrations, shown at 3, to facilitate fishing in case the jar should fail to operate eilectively. The lower end of the axial bore through the socket 5 is provided 10 v with screw threads 8, holding an inner jar member, comprising a jar mandrel 1, provided with an axial bore for the electrical conductor and with a thickened lower end, forming, for example,

a T-shaped jar head as shown at III. The jar mandrel is adapted to move. slidingly through an axial bore 8 in the upper part of an outer jar member orjar body 9. The :lar body is an elongated metallic bar oi generally cylindrical shape having a longitudinal slot I2 through its 20 middle portion, the jar head III being adapted to move axially within said slot. 'I'he inner and the outer jar members are capable of telescopic motion with regard to each other, the mandrel 'l sliding through the bore 8, and the jar head III moving withinvthe slot I2. 'I'he extent of this motion is limited in one direction by the abutment oi' the lower face of socket 5 against the upper face of the jar body 9, and in the other direction by the abutment of jar head I0 against 30 the upper end o1' the longitudinal slot I2. The conductor I passes through the axial bore o1' the jar mandrel and the jar head, and is housed, below the lower face of the Jar head within a ilexlble sheath or shielded conduit II, which is aiiixed between said lower face oi' the jar head and the lower end of slot I2. This sheath may consist, for example, oi a. length of a coiled resilient tubing, or may be formed by a thin metallic wire tightly wrapped around the insulated 40 conductor. The length oi' the shielded conductor coiled below the jar head is selected in such a manner that it is not fully expanded even at the moment when the jar head abuts the upper end of the slot l2 at the end or its upward stroke, 45 so that the conductor is never subjected to ten- On the other hand, the length of the jar mandrel and oi the slot I2 is selected In such a manner as to provide an adequate space to house the compressed coiled conductor when the lower face o1' socket 5 abuts the upper face of the jar body 9 at the end of the downward stroke of inner member, so that the conductor cannot be crushed betweenthe jar head and the lower end oi' slot I2. 'I'he purpose of the resilient spiral 55 Iscoping motion oi' the jar.

The lower end of the jar body 9 has an axial bore providing a passage for the electrical conductor, which may be suitably clamped therein to prevent wear due to friction. Any suitable means, such as a tapped box I3 at the lower end of the jar body may be used to attach the jar to any desired electrical device, such as surveying, logging, orienting thermometric and water locating instruments, gun perforators, cement vibrators, shing magnets, etc.

Fig. 4 shows a somewhat diierent embodiment of the present invention, wherein the outer jar members or jar body comprises a hollow cylinder 9B, closed at both ends by suitable heads. For example, the upper end may be closed by a screw-threaded plug 9A, provided with an axial bore forming a passage for the mandrel of the inner member. 'Ihe coiled conductor-is housed below the jar head I in a closed chamber I2 formed within said hollow cylinder between the jar head I0 and the lower head 9C of the jar body and is eiectively protected against injury by outside bodies. -The protective sheath II around the coiled conductor may therefore be' omitted, if desired. However, its use has also since it insures a uniform coiling of the. conductor and prevents breaks due to irregular coiling and creasing. A spiral or helical sheath, snugly fitting within the walls of the chamber I2 may be conveniently used in this case.

In operation, the jar mechanism is attached to a desired electrical device and is lowered therewith into the well at the end of a cable comprising an insulated electrical conductor. If desired, the jar may be lowered into the well at the end of a piping or tubing string, or at the .end of a sucker rod string, the insulated conductor being run inside the tubing string or alongside the sucker rod string. The socket is provided in such cases with suitable attaching means connecting it to the tubing, piping or rod string.

'I'he jar is lowered into the bore hole and maintained therein either in its extended position or in a contracted (or closed) position during the operation of the electrical device. If it is in its extended position, it is free to operate telescopically at any time that the jar body or the instrument aixed to the jar body becomes lodged or stuck in the bore hole. If it is in a contracted (or closed) position, that is, with the upper face of the jar body abutting the lower face of the cable socket, the jar is maintained in this position by means oi' a frangible shear pin or pins IIIA holding the inner and outer jar members in fixed relationship to each other, 'as shown in Fig. 2.

If the apparatus becomes stuck or jammed in the bore hole, a suiiicient pull is exerted on the cable to breakl the shear-pin, whereupon the cable socket 5 is raised with the cable, causing the jar mandrel to slide through the axial bore in the jar body, until a sharp blow is struck by the jar head against the upper end oi the slot I2 (Fig. 1) or against the plug` 9A (Fig. 2). This f procedure may be repeated several times until the apparatus is sufliciently freed from the obstruction to allow it to be raised without danger of cable rupture. Y

It will be seen that a jar constructed according to the present invention allows electric current to be supplied at all times to the electrical device attached to the jar. For example, if the jar is used with a, shing magnet, used to retrieve tools lost in the hole, it is essential that electric current be supplied to the magnet during the time the jar is operated, since any interruption of the current would cause the magnet to release its load and result in the failure of the whole operation. Likewise, if the jar is used with a cement vibrator such, forexample, as describedin the co-pending application, Ser. No. 117,914, led Deoember 28, 1936, by Clarence R. Dale, it is important that the vibrator and the jar be capable of operating simultaneously, since the vibrating action of the vibrator cooperates with the jarring action of the jar in disengaging the apparatus from the obstruction.

It is understood that the jar mechanism forming the subject matter of the present invention is in no way limited to the embodiments described above, but is capable of various modications coming within the scope of the appended claims. For example, it is obvious that the inner member may be attached to the electrical device, and the outer member to the cable. In particular it should be pointed out that the force of the blows delivered by the jar can be controlled by properly Varying the length of the jar mandrel and theweight of the two relatively movable parts of the jar mechanism. The latter object may be been found advantageous with this type of jar,

socket or to the jar body in a manner understood by those versed in the art.

I claim as my invention:

1. In a jar for an electric device lowered into a borehole, supporting means for the jar, an elongated inner jar member, an elongated longitudinally recessed outer jar member, one of said members being attached to the supporting means and the vother to the electric device, said members being linked for'limited axial telescopic motion with regard to each other, a bore through each member, an insulated conductor associated with the supporting means and passing through the bore in the members to the electric device, said conductor having a coiled section housed within the recessed jar member, said coiled section beingI oi sufficient length to permit a full telescopic strokevof the jar members with regard to each other.

2. In a jar for an electric device lowered intoA a borehole, supporting means for the jar, an elongated inner jar member, an elongated longitudinally recessed outer jar member, one of said members being attached to the supporting means and the other to the electric device, said membersl v coiled section being of sufficient length to permit a full telescopic stroke of the jar members with regard to each other, and a pin holding the two members in fixed relationship to each other.

3. In a jar for an electric device lowered into a borehole, supporting means for the jar, an elongated inner jar member, an elongated longitudinally recessed outer jar member, one of said members being attached to the supporting means` and the other to the electric device, said members being linked tor limited axial telescopic motion with regard to each other, an axial bore through each member, an insulated conductor associated with the supporting means and passing through the axial bore in the members to the electric device, said conductor having a coiled section housed in a resilient helical sheath within the recessed jar member, said coiled section being oi' suillcient length to permit a full telescopic stroke oi! the jar members with regard to each other.

4. In a jar for an electric device lowered into a borehole. supporting means for the jar, an elongated tubular inner member attached to said supporting means, said member having a thickened lower portion, an elongated solid outer jar member attached to the electric device, means linking said members for limited telescopic motion with regard to each other comprising an axial bore in the upper portion of the solid outer member adapted to llt slidingly around the inner member, a longitudinal slot through the middle portion oi' the solid outer member, said slot having a width at least equal to the diameter of said bore, the thickened lower portion of the inner member being adapted to move axially within the upper portion o! said slot, an axial bore through the lower portion of the outer member, an insulated conductor associated with the supporting means and passing through the` tubular inner member and through the slot and the lower telescopic stroke of the jar members with regard to each other. f

5. In a jar for an electric device lowered into a borehole, supporting means for the Jar, an

elongated inner tubular jar member attached to the supporting means. said member having a thickened lower portion, an elongated outer tubular Jar member, a head closing said member at each end, means linking said members for limited telescopic motion with regard to each other comprising an axial bore through the upper head ofthe outer member adapted to ilt slidingly around the inner member, a chamber below said head, the thickened portion of the inner member being adapted to move axially within the upper portion of said chamber, an axial bore through the lower head of the outer member, an insulated conductor associated with the supporting means and passing through the tubular members to the electric device, said conductor having a coiled section housed within the lower portion of the chamber in the outer member below the thickened portionI of the inner member, said coiled section being `of sumcient length to permita full telescopic stroke of the jar members with regard to each other.

, ALBERT S. BAPTIE.

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