US3327784A

US3327784A - Apparatus for releasably connecting well tools to a supporting member

Info

Publication number: US3327784A
Application number: US417619A
Authority: US
Inventors: George H Pardue
Original assignee: Schlumberger Technology Corp
Current assignee: Schlumberger Technology Corp
Priority date: 1964-12-11
Filing date: 1964-12-11
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27

Description

June 27, 1967 G. H. PARDUE 3,327,784

APPARATUS FOR RELEASABLY CONNECTING WELL TOOLS TO A SUPPORTING MEMBER 2 Sheets-Sheet Filed Deo. 1l, 1964 6Go/y@ H. Para/ue United States Patent O 3,327,734 APPARATUS FR RELEASABLY CONNECT- ING WELL TLS T A SUPPRTING MEWER George H. Pardue, Houston, Tex., assignor, by mesne assignments, to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Dec. l1, 1964, Ser. No. 417,619 13 Ciairns. (Cl. 16o-65) ABSTRACT 0F THE DISCLSURE This disclosure is directed to means for securely connecting a well tool to a supporting member in such a manner that the well tool can be selectively disconnected therefrom should the tool be stuck in -a well bore. In one manner of operation, application of a predetermined tension load on the supporting member will disconnect it from the stuck well tool. In another manner of operation, an electrical signal followed by a lesser predetermined tension load will disconnect the tool from its supporting member.

Accordingly, as will become apparent, it will be seen that invention relates to subsurface tools and is particularly conce-med with apparatus for releasably suspending such tools from a cable.

In the operation of cable-suspended subsurface tools, such as various measuring and logging devices, subsurface conditions may cause the tool to become stuck. When this occurs, and the tool cannot be dislodged by application of a reasonably safe cable tension, it becomes necessary to disconnect the cable from the tool. Preferably, disconnection should occur at or adjacent the tool to facilitate retrieving the cable intact.

A cable that has parted by excess tension is not only itself damaged or lost but frequently interferes with subsequent removal of the tool, as by conventional lishing operations. It has, therefore, become conventional to provide a so-called weak-point connection between the cable and tool. This may be done by placing :a weakened member in the line at or adjacent the cable head on the tool to provide a point of reduced tensile strength. When this is done and the tool becomes stuck, the application of suicient tension on the cable will break the Weakpoint and disconnect the cable from the tool.

Such weak-points must, however, have suicient tensile strength to support the static weight of the tool and any loads induced by drag in raising the tool as well as such additional tension as may reasonably be applied in any effort to dislodge the tool if it becomes stuck.

When the tool is downhole and the cable under tension, the point of greatest cable stress will be at or near the surface. For example, if a cable having an average tensile strength of 12,000-pounds is used in conjunction with a conventional weak-point having an average tensile strength of 6,200-pounds and 6,0G0-pounds of cable is within the bore hole when the tool sticks, additional tension will probably break the cable at or near the surface before the weak-point can be loaded beyond its tensile strength. Thus, a conventional weakpoint may become inoperable if the tool becomes stuck at a substantial depth. Moreover, this particular problem with conventional weakpoints tends to increase with operating depth since the footage which may be handled by the cable winch is greatly dependent upon cable diameter and, as diameter is reduced to increase footage, average tensile strength is sacrificed.

Further, the tension at which a conventional weakpoint will break must necessarily be empirically deter- ICC mined. Itis therefore necessary to actually break representative samples from each lot of weak-points manufactured, average the tensile force required to break them and take that average, plus or minus the deviation encountered (typically about I'ive to ten percent) as the average tensile strength of each weak-point in the lot. Thus, in the hypothetical example just given, that weakpoint might actually break several hundred pounds above or below 6,200-pounds. As a result, unless great pains are taken, there is always an uncertainty about the amount of cable tension that may be safely applied in attempting to dislodge a stuck tool, as well as the .tension actually required to break the weak-point.

If in the course of tensioning the cable to break a conventional weak-point, the cable becomes key-seated (i.e., cuts into, and becomes bound by, the wall of a bore hole) as sometimes occurs in soft walled bore holes, before suiiicient tension is developed to either dislodge a stuck tool or break the weak-point, release of the cable adjacent the tool is frustrated. When this occurs, the cable tension must be increased until the cable itself breaks. Such a break will be usually at or near the surface, but may be at a point of latent cable damage between the surface and the key-seat.

According to the present invention, release apparatus is provided for selectively releasing the cable by the application of any desired tension Ibetween minimum and maximum predetermined values, using release means which may be electrically operable from the surface, or simply by the application of a precisely predetermined maximum tension load.

More specifically, this invention is characterized by a mechanically disengageable member affording a releasable connection. Such a member may be provided by a collet having a plurality of radially disposed depending fingers terminating in angulated lugs which are securely gripped between movable opposed abutments within a cable head. An electrically releasable latching device retains one abutment normally engaged with one side of the collet lugs. The other abutment is normally positioned against the opposite side of the collet lugs and pre-loaded spring means are provided to prevent withdrawal of this other abutment unless and until a precisely predetermined tension is applied. Thus, cable release may occur selectively either when the latched abutment is released from engagement with the collet lugs in response to an electric signal or when the pre-loaded abutment is released from engagement with the collet lugs in response to application of a cable tension sufficient to overcome the pre-load springs.

More particular understanding of the invention may be had from the following description of one embodiment thereof which has been illustrated in the appended drawings, wherein:

FIGURE l is an elevation view partly cut-away.

FIGURE 2 is a section view taken along line 2 2 of FIGURE 1.

FIGURE 3 is a section view tken along line 3 3 of FIGURE 2.

FIGURE 4 is a partial section showing the lower abutment in unlatched condition.

FIGURE 5 is a partial section showing the lower abutment moved downwardly from the collet lugs and the collet being withdrawn.

FIGURE 6 is a partial view showing the pre-loaded abutment and collet being withdrawn from locking engagement with the lower abutment.

FIGURE 7 is a partial view showing the pre-loaded abutment in completely withdrawn position, and the collet being released.

In the illustrated embodiment of this invention, as shown in FIGURE 1, -a winch carries a cable 11, which may conveniently include a plurality of electrical conductors 12. In operation, cable 11 typically passes from winch 10 under sheave 13 and over sheave 14, which is equipped with a tensiometer 15. After passing over sheave 14, cable 11 is connected to a cable head 16 from which a tool 17 may be suspended in a well bore by a threaded adapter 18.

As shown in FIGURE l, cable head 16 includes a cylindrical housing 10 adapted to threadably receive adapter 18 at its lower end and to slidably receive a so-called boot 20 at its upper end. With continued reference to FIGURE 1, it will be seen that the central load supporting member 21 of cable 11 is secured to the upper end of a shank 22 by means of swaged socket 23. Then, as best seen in FIGURE 2, shank 22 extends coaxialiy into housing 19 with its lower end being formed into a collet 24 comprised of radially disposed depending fingers 25, each having outwardly facing angulated lugs 26.

With continued reference to FIGURE 2, it will be seen that collet lugs 26 are securely engaged between an upper abutment 27 and a lower abutment 28 which abutments are carried by and operable within a cylinder 29 received in housing 19. Cylinder 29 is supported in housing 19 by securing its flanged lower end 33 between internal shoulder 34 of housing 19 and the upper face 35 of plug 30. In turn, plug 30 is held by threading adapter 18 into the lower end of housing 19 until adapter 18 securely engages the lower end 32 and intermediate shoulder 31 of plug 30. At its upper end, cylinder 29 is sealed4 by a exible bellows 36 the upper and lower ends of which are respectively secured to shank 22 and cylinder 29.

Intermediate the ends of cylinder 29, its bore is reduced in diameter to provide an internal lannular shoulder 37. A collet sleeve 38 is slidably disposed around a reduced portion of shank 22 and collet 24. Lateral pin 39 in a slot at the upper end of sleeve 38 prevents the sleeve 38 from rotating relative to shank 22. Sleeve 38 has an enlarged lower end with a peripheral flange 40 which rests on shoulder 37 and an internally formed surface forming abutment 27 which engages the outer surfaces of collet lugs 26. A plurality of stacked Belleville washers 42 are disposed around the collet sleeve 38 and carried by the peripheral flange 40. A sleeve 43 is slidably disposed around the collet sleeve 38 and shank 20 and engages the upper end of the washer stack 42. An externally threaded adjusting nut 44 threadably engaged within the uppermost end of the bore of cylinder 29 is utilized to hold the washer stack 42 compressed and to urge ange 40 of the collet sleeve 38 downwardly against the upper side of shoulder 37 with a force of predetermined magnitude.

A cup-type latch housing 45 is disposed Within the bore of cylinder 29 with its upper closed end engaged against the underside of shoulder 37. A latch carrier body 46 is slidably received in housing 45 and has a reduced-diameter frusto-conical portion which forms abutment 28 projecting upwardly from its upper end. Abutment 28 extends through an opening in the closed end of latch housing 45 and normally engages the inner surfaces of collet lugs 26. A plurality of depending fingers 48 are pivotally suspended within circumferentially spaced longitudinal slots in the annular body 46. At the lower free end of fingersV 48, inwardly extending recesses 49 are provided to engage the inward side yof a plurality of ball members 50 loosely received within holes through the side of body 46. Housing 45 has annular recesses 51 in which the outward side of the ball members 50 are normally received to secure the annular body 46 in its uppermost position.

Below body 46, a solenoid 52 is mounted within the housing 45 and includes a solenoid coil 53 having an upper pole piece 54. A tubular non-magnetic plunger 55 is mounted on an armature 56 in the position illustrated. Plunger 55 extends upwardly into the hollow interior of body 46 and has an enlarged non-magnetic upper portion 57. A plurality of balls 58 are loosely mounted in recessed porons of the enlarged plunger portion 57 and held in this position by a follower sleeve 59 which is biased upwardly by a light spring 60.

Each of the balls 58 are suitably positioned to be normally engaged against the inner surfaces of an offset tip portion 61 of the pivoted fingers 48 so long as the solenoid 52 is de-energized. Thus, so long as each set of

balls

50 and 58 remains laterally opposite one another, the free ends of each of the pivoted fingers 48 are held therebetween to prevent body 46 from shifting downwardly, thereby maintaining abutment 2S firmly engaged against the inside of collet lugs 26.

Electrical circuitry suitable for energizing solenoid 52 is readily provided by electrical conductor lead 62 taken from the lower end of one of conductors 12 which normally extend between tool 17 and its associated surface equipment. When assembled, cylinder 29 is preferably hermetically sealed and oil-filled to achieve maximum protection from corrosive well-liuids, with the environmental pressure differential being compensated by the dilerential bellows 36.

To prevent inadvertent cable release by accidental actuation of solenoid 52, las hereinafter explained, a safety is provided. This safety takes the form of a weak-point designed to support a minimum load, e.g., the static load of a freely supported tool. Such weak-point comprises a replaceable rod 63 of non-magnetic material threadably connected at one end to shank 22 and extended through plunger 55 where it is connected to head 16 through plate 64 and housing 45 with a nut 65. Rod 63 has a reduced, weakened cross-section at 66 so as to break at, say LOGO-pounds tension plus or minus 10%. As best seen in FIGURE 2, so long as lugs 26 are engaged by

abutments

27 and 28, no tension is applied to the rod 63 and the load is transmitted from the collet to abut* ment 27. However, when lugs 26 are released, the full load is immediately transferred to rod 63. If the load is above the minimum, rod 63 will break at 66.

In the event a tool carried from head 16 becomes stuck, cable 11 may be released from the head in either of two ways. If it is desired to release the cable 11 at a reduced tension, solenoid 52 is first electrically energized, e.g. by passing energizing current to solenoid 52 through that one of conductors 12 in the cable 11 which is connected to conductor 62. When energized, armature 56 is pulled upwardly toward upper pole piece 54 to elevate the enlarged plunger portion 57. As the plunger portion 57 moves up, balls 58 roll upwardly along the inner surfaces of the latch lingers 48 from their position shown in FIG- URE 2 to the position shown in FIGURE 4. Once the inner balls 58 have cleared the offset .tip portion 61 of lingers 48, the fingers are free to swing inwardly a suicient radial distance to permit the outer balls 50 to also move inwardly and roll out of the annular recesses 51. It will be appreciated, of course, that once the inner balls 58 have moved into their position as shown in FIG. 4, the body 46 is held in its uppermost position only by the biasing effect of spring 67.

Accordingly, whenever only a slight amount of tension is applied to cable 11, the upward pull on shank 22 will force the collet fingers 25 to contract as the upper abutment 27 cams the collet lugs 26 inwardly. As the collet lugs 26 move inwardly, the camming action of the inner faces of the lugs on the frusto-conical surface of the lower abutment 28 will shift body 46 downwardly.

Once the body 46 has moved downwardly only a slight distance, the lower abutment 28 no longer restrains the collet lugs 26; and the lingers 25 are then retracted suiiiciently to free the lugs from the upper abutment 27 as shown in FIGURE 5. It will be appreciated that once the lugs 26 are free of abutment 27, the full load on the cable 11 is then applied to the weak-point or rod 63. Once the cable load has reached the predetermined design tensile strength of the weakened portion 66 of rod 63,

the weakened portion will fail. Then, the shank 22 and all elements thereabove on the shank will be pulled out of the housing 19. As the shank 22 moves upwardly, the flexible bellows 36 are, of course, broken. As seen in FIGURE l, the boot 20 is only splined to the housing 19 and will easily pull out of the housing.

If the electrical system should be inoperative or should there be some other reason for not utilizing it, the cable 11 can also be released mechanically by pulling on the cable. In this instance, sufficient tension must first be applied to overcome the oppositely directed predeter mined load applied by the Belleville washers 42. Once this predetermined load has been equaled, the upper abutment 27 will shift very slightly upwardly away from flange 37. As additional tension is applied on the cable 11, the additional force will then be imposed on the weak-point 63 until the added force has reached the level necessary to break the weakened portion 66. Once this weakened portion 66 breaks, the additional force is suddenly transferred to the Belleville washers 42 which then further compress a sufficient distance to allow collet 24 and flange 40 to move upwardly. Once the collet fingers 25 have moved upwardly a short distance, the inner surfaces of the collet lugs 26 are no longer in contact with the lower abutment member 28 and the collet lingers 25 are free to contract and slip upwardly into collet sleeve 38. When this occurs, cable 11, shank 22, and collet 24 may be withdrawn from head 16 in the manner shown in FIG-

URES

6 and 7.

Among the several advantages of this invention is the capacity of the release apparatus to withstand jarring without Ipremature release. This is because freeing of lugs 26 by releasing balls 50 requires that body 46 and enlarged plunger portion 57 move toward each other. Since jarring, whether from above or below, will produce forces acting in only one direction, this required counter-movement of body 46 and the enlarged plunger portions 57 will not occur. Additionally, the viscosity of the oil within cylinder 29 will dampen any movement of body 46 and plunger portion 57.

It should be noted that the

springs

60, 67 and 69 will aid in holding the members with which they are engaged in position to maintain the apparatus latched. Moreover, these

springs

60, 67 and 69 will permit the electrical release system to be tested before the apparatus is lowered into a well bore since once the solenoid 52 is deenergized, the springs will restore their respective members to their normal positions. It will also be appreciated that spring 60 and ball follower 59 will ensure that balls 58 are free to roll rather than having to slide upwardly. Thus, the load that the solenoid 52 must operate against is minimized by encountering rolling, rather than sliding, friction.

It will be appreciated that with the weak-point 63 the release force can be much more precisely known than with conventional systems since, unlike conventional mass-produced weak-points, the weak-point 63 will be designed to support only a few hundred pounds. By employing the apparatus of the present invention in the previous example, the weak-point 63 can be designed to have an average tensile strength of L200-pounds and a predetermined load of 5,000-pounds applied to the Belleville washers 42. Thus, assuming the margin of error in determining the breaking strength of the weak-point 63 to be the release point will vary only 1Z0-pounds above or below the design release point of 6,200-pounds as contrasted with the Wide range typical of conventional mass-produced weak-points designed for higher loads.

Devices embodying this invention might take various forms and may employ a variety of equivalent means. Thus, the collet means might be replaced with other connection means; the washer stack might be replaced with a spring or other pre-load means; a tool might be connected directly rather than through a cable head; a tool might employ only the electrically operative release feature; or, when non-electrical cable `is used a tool, might employ only the yieldable pre-loaded release feature.

Thus, the scope of the invention taught herein is much broader than the one embodiment illustrated and described, such description and illustration being given solely to facilitate further understanding of the invention by those skilled in the art to which it pertains. Accordingly, the invention will readily admit of other equally effective embodiments all of which are intended to be within the scope of the appended claims.

I claim: 1. In a subsurface tool adapted to -be suspended from a cable extending to the surface, apparatus operable from the surface for releasing said tool from a cable, said apparatus comprising:

rst and second co-engaging companion members respectively connected to said tool and adapted for connection to a cable; means for releasably connecting said companion members including stop means on one of said companion members .arranged and adapted to engage the other of said comp-anion members for constraining said other companion member, said stop means being movable from a normal position in engagement with said other companion member for connecting said companion members to another position for disconnecting said companion members; means for retaining said stop means in said normal position and operable from the surface and through a cable to release said stop means for movement to `said other position; and means for releasably securing said companion members including a breakable linking member normally fastening said companion members together. 2. As a sub-combination for use in a subsurface tool adapted to Abe suspended from a cable extending to the surface, apparatus operable from the surface for releasing such a tool from a cable, said apparatus comprising:

lirst and second `co-engaging compani-on members respectively adapted for connection to a tool and a cable; means for releasably connecting said companion members including firs-t and second stop means on one said companion members to connecting said companion members;

force-applying means retaining said first s-top means in said normal position applying means being directed force applied through said second companion member in excess of said predetermined magnitude to overcome said force-applying means and move said rst stop means to said other position. 3. In a subsurface tool adapted to be suspended from a ca'ble extending to the surface, apparatus operable from the surface for releasing said tool from a cable, said apparatus comprising:

first and second co-engaging companion members respectively connected to said tool and adapted for connection to a cable; means for yreleasably connecting said companion members including first and second stop means on one of said companion members for constraining the other of said companion members, said rst stop means lbeing movable independently of said second stop means from a normal position in engagement with said other companion member for connecting said companion members to another position for disconnecting said companion members;

and spring means retaining said first stop means in said normal position and urging said first stop means toward said second stop means with a spring force of predetermined magnitude, said spring means being yieldable in response to an oppositely-directed force applied through said second companion member in excess of said predetermined magnitude to overcome said spring force and move said first stop means to said other position.

7. In a subsurface tool suspended from a cable extending to the surface, apparatus operable from the surface for releasing said tool from said cable, said apparatus comprising:

first and second co-engaging companion members respectively connected to said tool and said cable; means for releasably connecting said companion members including first and second movable stop means 4. In a subsurface tool adapted to be suspended from Aa cable extending to the surface, apparatus operable from the surface for releasing said tool from a cable, said apparatus comprising:

first and second tro-engaging companion members erespectively connected to said tool and adapted for connection to a cable; means for releasably connecting said companion rnembers including first and second stop means on one 0n one of Said Companion members arranged and of said companion members -ior constraining the adapted to engage the other of said companion memother of said companion members, said first stop bers for constraining Said other Companion rnern' means being movable from a normal position in ber, eeen of Said Stop IneanS being independently engagement with said other companion member for movable from a norrnnl Position in engagement With connecting said companion members to another posi- Said other Companion member for Connecting Said tion for disconnecting Said Companion members; companion members to another position for disconspring means retaining said first stop means in said neetlng Sad Companion rneInberS;

normal position and urging said irst stop means toand first and second means for respectively retaining ward said second Stop Imeans with a force of presaid first and second stop means in their said normal determined magnitude, said spring means being yield- Positions, each of Seid retaining Ineens being Selecable in response to an opposite1y-directed force on tively operable from the Surface and through Said said first stop means and in eXeeSS of Said predetefcable to release their associated one of said first and mined magnitude -to move said first stop means to Second SioP means for independent movement to said other position; their said other positions.

and means for releasably Securing Said eompanion 8. In a subsurface tool adapted to be suspended from a cable extending to the surface, apparatus operable from the surface for releasing said tool from said cable, said apparatus comprising:

first and ysecond co-engaging companion members remembers including a breakable member normally fastening said companion members together.

5. in a subsurface tool adapted t-o be suspended from a cable extending to the surface, yapparatus operable from the Surface for releasing Said tool ,from a cable, said ap spective'ly connected to said tool and adapted for paratus comprising: connection to a cable;

rst and Seeond no engaging Companion members 1.e means f or releasably connecting said companion memspectively connected to said tool and adapted for conbers meludmg first and Second movable Stop Ineens nection to acable; on one of said companion members arranged and .means for releasably Connecting said Companion meuk adapted to engage thel otherl of said companion bers including first `and second stop means on one of members for constraining Said other. compamon said companion members arranged .and adapted to member @ash of 'Sad Stop mean belng Independent' engage and constrain the other of said companion 1y movrbl from a non nal Posltlon 1n engagement members, said first stop means being movable indewith Sad other Compamon member for ,Connecting pendently of said second stop means from a normal Sald cofflpamqn member? to another Posltlon for 15" position in engagement with said other companion connectmg Sad compamon memlefs member for Connecting Said companion members to first and second means for respectively retaining said another position for disconnecting said companion rst, and Second Stop means m their Sall normal members; positions, each of said retaining means being selecmeans for retaining Said rst stop means in Said normal tively operable from the surface and through a cable position; to release their associated one of said first and second stop means for independent movement to their said other positions; and means for releasably securing said companion members including a breakable linking member normally fastening said companion members together. 9. In a well tool adapted to be suspended in a Well bore from a cable having electrical conductor means and extending to the surface of the ground, selectively-operable release apparatus comprising:

first and second co-engaging companion members respectively connected to said tool` and adapted for connection to such a cable; means for releasably connecting said companion memand means responsive to an electrical sign-al `for disabling said retaining means and freeing said first stop means for movement to said other position to disconnect said companion members. 60 6. In a subsurface tool adapted to be suspended from a cable extending to the surface, apparatus operable from the surface for releasing said tool from a cable, said apparatus comprising:

first and second co-engaging companion member re- 6 respectively connected to said tool and adapted for connection to a cable; means for releasably connecting said companion members including first and second stop means on one of bers including first and second movable stop means sind Companion 'rnernberS arranged 'and adapted 'EO on one of said companion members arranged and engage and constrain the other of said companion adapted to engage the other of said companion memmembers, said'first stop means being movable from bers for constraining said other companion member, a normal position in engagement with said other each of said stop means being movable from a norcompamon member for connecting said companion mal position in engagement with said other eom panion member for connecting said companion memand means for releasably securing said companion members to another position for disconnecting said combers including a breakable linking member normally panion members; fastening said companion members together. first means for retaining said first stop means in said 12. In a subsurface tool adapted to be suspended from normal position electrical means operative from the a cable extending to the surface, apparatus operable from surface and through such a cable to actuate said first the surface for releasing said tool from said cable, said retaining means to a position for selectively releasing apparatus comprising: said first stop means for movement to said other first and second co-engaging companion members reposition; and spectively connected to said tool and said cable; spring means retaining said second stop means in said l0 means for releasably connecting said companion memnormal position for urging said second stop means bers including first and second movable stop means toward said first stop means with a force of a preon one of said companion members arranged and determined magnitude, said spring means being yieldable in response to a force applied through said second companion member in excess of said predetermined magnitude to overcome said spring force and selectively move said second stop means to said other position.

adap-ted to engage the other of said companion members for constraining said other companion member, each of said stop means being movable from a normal position in engagement with said other companion member for connecting said companion members to another position for disconnecting said companion members;

latch means for retaining said first stop means in said normal position and including means responsive to an electrical signal for disabling said latch means and moving said first stop means to said other position;

and spring means for retaining said second stop means in said normal position and including means respon- 10. In a subsurface tool adapted to be suspended from a cable extending to the surface, apparatus -operable from the surface for releasing said tool from a cable, said apparatus comprising:

first and second co-engaging companion members respectively connected to said tool and adapted for connection to a cable; means for releasably connecting said companion members including first and second stop means on one of said companion members arranged and adapted to engage the other of said companion members for sive to a tension of predetermined magnitude on said other companion member for disabling said spring means and moving said second stop means to said constraining said other companion member, each of said stop means being independently movable from a normal position in engagement with said other other position. 13. As a sub-combination for use in a subsurface tool adapted to be suspended from a cable extending to the companion member for connecting said companion Surface, apparatus operable from the surface for releasmembers to another position for disconnecting said ing such a t-ool from such a cable, said apparatus comcompanion members; prising: latch means for retaining said lirst stop means in said first and second co-engaging companion members renormal position and operable from the surface and spectively adapted for connection to a tool and a through a cable to free said first stop means for cable; movement to said other position; means for releasably connecting said companion memand spring means retaining said second stop means bers including first and second movable stop means in said normal position for urging said second stop means toward said first stop means with a force of predetermined magnitude, said spring means being yieldable in response to a force directed away from on one of said companion members arranged and adapted to engage the other of said companion members for constraining said other companion member, each of said stop means being movable from a normal said first stop means acting on said second stop means and in excess of said predetermined magnitude to move said second stop means to said other position. 11. In a subsurface tool suspended from a cable extending to the surface, apparatus operable from the surface for releasing said tool from said cable, said apparatus comprising:

first and second co-engaging companion members respectively connected to said tool and said cable; means for releasably connecting said companion members including first and second movable stop means on one of said companion members arranged and adapted to engage the other of said companion members for constraining said other companion member, each of said movable stop means being movable from a normal position in engagement with said other companion member for connecting said companion members to another position for disconnecting said companion members; latch means for retaining said first stop means in said position in engagement with said other companion member for connecting said companion members to another lposition for disconnecting said companion members;

spring means for retaining said second stop means in said normal position and including means responsive to a tension of predetermined magnitude on said other companion member for disabling said spring means and moving said second stop means to said other position;

and means including a breakable member of predetermined strength for normally connecting said companion members independently of said stop means.

References Cited UNITED STATES PATENTS normal position and operable from the surface and herman 2941686 through said cable to free said first stop means for agan 2,296,397 9/1942 Mhlbach 294-86.18 movement to said other position, spring means retaining said second stop means in said 2,618,345 11/1952 Tucker 166123 normal position for urging said second stop means 2,778,428 1/1957 Baker et al 166*125 toward said first stop means with a force of prede- 2,872,238 2/1959 Damn 294-8618 termined magnitude, said spring means being yield- 3,203,531 9/ 1965 Tamplen 166-125 able in response to a force acting on said second stop means and in excess of said predetermined magnitude CHARLES E' O CONNELL Prmary Exammer' to move said second stop means to said other position; D. H. BROWN, Assistant Examiner.

Claims

5. IN A SUBSURFACE TOOL ADAPTED TO BE SUSPENDED FROM A CABLE EXTENDING TO THE SURFACE, APPARATUS OPERABLE FROM THE SURFACE FOR RELEASING SAID TOOL FROM A CABLE, SAID APPARATUS COMPRISING: FIRST AND SECOND CO-ENGAGING COMPANION MEMBERS RESPECTIVELY CONNECTED TO SAID TOOL AND ADAPTED FOR CONNECTED TO A CABLE; MEANS FOR RELEASABLY CONNECTING SAID COMPANION MEMBERS INCLUDING FIRST AND SECOND STOP MEANS ON ONE OF SAID COMPANION MEMBERS ARRANGED AND ADAPTED TO ENGAGE AND CONSTRAIN THE OTHER OF SAID COMPANION MEMBERS, SAID FIRST STOP MEANS BEING MOVABLE INDEPENDENTLY OF SAID SECOND STOP MEANS FROM A NORMAL POSITION IN ENGAGEMENT WITH SAID OTHER COMPANION MEMBER FOR CONNECTING SAID COMPANION MEMBERS TO ANOTHER POSITION FOR DISCONNECTING SAID COMPANION MEMBERS; MEANS FOR RETAINING SAID FIRST STOP MEANS IN SAID NORMAL POSITION; AND MEANS RESPONSIVE TO AN ELECTRICAL SIGNAL FOR DISABLING SAID RETAINING MEANS AND FREEING SAID FIRST STOP MEANS FOR MOVEMENT TO SAID OTHER POSITION TO DISCONNECT SAID COMPANION MEMBERS.