Safety Joint Method And Apparatus

Abstract

A method and apparatus for a subsurface safety joint connectable in a well conduit to effect positive separation of the well conduit when such separation is desired. The safety joint release is effected alternatingly by a predetermined fluid pressure in the bore of the well conduit or by rotation of a portion of the well conduit.

Description

BACKGROUND OF THE INVENTION

This invention relates to the field of a method and apparatus for a releasable subsurface safety joint in a well and more particularly to a safety joint that may be operated either by fluid pressure or by mechanical movement to effect release of the safety joint.

Some subsurface well tools connectable in a well tubing string have neither a symmetrical shape nor a concentric relationship with the tubing string. Such tools often required employment of special connecting joints, called safety joints, below the tool for detaching the tool and a portion of the tubing when it was desired or necessary to retrieve the tool to perform maintenance work thereon. Some safety joints were released by either right-hand or left-hand rotation of the portion of the tubing above the safety joint, while other joints required reciprocation in conjunction with rotation to effect release. Safety joints requiring rotation of the well tubing were undesirable because of insufficient clearance to enable the necessary rotation to operate the joint which was often not available in plural completion wells and, in addition, the risk of threadedly disengaging a threaded joint of the well conduit was great. Other joints utilizing partial rotation have not been widely received because the torsion deformation of the tubing made determination of the relative position of the tubing at the joint from the well surface unreliable.

Still others have employed reciprocation of the tubing to shear a connecting pin to release the joint, but well pressure may effect undesired shearing under certain well pressure conditions. Other safety joints were released by applying fluid pressure in a certain manner. While these often had the desirable feature of not requiring rotation to release or separate the tools, they were rendered inoperative if the tubing string developed a leak. It was then necessary to pull the entire string to retrieve the tool.

The advent of subsurface safety valve controlled by the use of one or more small lines run in parallel with the tubing string to operate the valve has made it even more imperative that reliable safety joints be provided. The likelihood of damage to the control lines during the retrieval and setting of the valve rendering the valve inoperative emphasizes the need for a reliable, non-rotating, positive release safety joint and apparatus and method.

SUMMARY OF THE INVENTION

A method and apparatus for a subsurface safety joint connectable in a well conduit to effect desired release of a portion of the well conduit by either communication of a predetermined fluid pressure to the joint to free a plurality of connecting latch dogs or by a left-hand rotation of a portion of the well conduit. Means are provided with the portion of the safety joint left in the well to reconnect the well conduit with the safety joint.

An object of the present invention is to provide a new and improved safety joint apparatus.

Another object of the present invention is to provide a new and improved method for effecting positive release of a safety joint.

A further object of the present invention is to provide a new and improved safety joint having alternate means for effecting release of the safety joint.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are side views, partially in section, from top to bottom of the safety joint of the present invention prior to effecting separation of the safety joint;

FIGS. 2A and 2B are views similar to FIGS. 1A and 1B respectively, with the safety joint separation effected by left hand rotation;

FIGS. 3A and 3B, are views also similar to FIG. 1A and 1B, respectively, with the safety joint separation effected by a predetermined fluid pressure communicated by the bridge plug positioned in the bore of the safety joint;

FIG. 4 is a side view, partially in section, illustrating the lower half of the safety joint reconnected with the well conduit above the safety joint; and

FIG. 5 is a view taken along line 5--5 of FIG. 1B.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawings, the letter S generally designates the safety joint of the present invention which is adapted to be connected in and form a part of a casing, tubing or other well conduit C, whereby the upper portion of the conduit C can be released from the lower part of the conduit C. The lower portion of the conduit C is suitably supported (not illustrated) in the well by a hanger and the like to remain fixed in position when the safety joint S is released. As set forth hereinbelow, means are provided with the safety joint S for reconnecting the well conduit C with the safety joint S after separation thereof.

As illustrated in FIGS. 1A and 1B, the safety joint S includes a first or lower tubular member 10 and a second or upper tubular member 20 having aligned longitudinal bores 10a and 20a, respectively, formed therethrough. The lower tubular member 10 includes a threaded pin connection 11, formed thereon adjacent the lower or first end which is adapted for connecting the tubular member 10 with the well conduit C below the safety joint S. The upper tubular member 20 has a threaded box connection 21 formed in the bore 20a adjacent the upper for first end of the tubular member 20 for connecting the tubular member 20 with the well conduit C (FIG. 2A) above the safety joint S. When connected in the well conduit C, the safety joint S forms a portion thereof for communicating the flow through a bore X of the well conduit C and through the bores 10a and 20a of the tubular members 10 and 20 respectively. The bores 10a and 20a are slightly smaller in diameter than the box X of the well conduit C for a purpose to be more fully described hereinafter, but essentially provide a full opening through the safety joint S for effecting a minimum flow restriction. The tubular member 10 has a constant diameter inner surface 10b which defines the flow passge bore 10a an outer partially threaded surface 10c concentrically spaced from the surface 10b. The surface 10b extends upwardly adjacent the upper or second end of the tubular member 10 to an annular shoulder 10d. A tapered left hand thread 10e forming a continuous helical groove or recess in the tubular member 10 is formed in the outer surface 10c adjacent to the shoulder 10d and which also provides a continuous helical groove or recess below the thread 10e.

The upper tubular member 20 includes an outer sleeve 22 secured by threads 23 to a concentric inner tubular member 24. Suitable anti-rotation pins, not illustrated, may be employed to block rotational disengagement of the sleeves 22 and 24. The sleeve 22 mounts an O-ring 23a adjacent threads 23 to block leakage of fluid between the sleeve 22 and the sleeve 24.

Sleeve 22 includes a stepped lower inner surface 22a having threads 22b formed therein for releasably securing a cap ring 25 therewith. The sleeve 22 also includes a downwardly facing annular shoulder 22c connecting the surface 22a and a smaller constant diameter surface 22d which is concentrically spaced from the sleeve 24. The sleeve 22 has a port 22e formed therethrough above the annular shoulder 22c for communicating the annular space between the sleeve 24 and the surface 22d with the area adjacent the exterior surface 22f of the tubular member 22.

The inner sleeve 24 extends from the outer threads 23 to a downwardly facing annular shoulder 24a adjacent the threads 10f. The bore 20a is partially defined by the surfaces of the sleeve 24 including a full diameter conduit bore upper portion 24b, a bore restricting upwardly facing annular shoulder 24c and a constant diameter bore portion 24d having an inwardly projecting annular collar 24e formed thereon. The collar 24e provides an upwardly facing annular shoulder 24f for a purpose to be described more fully hereinafter and a downwardly facing annular shoulder 24g which is adapted to engage the upwardly facing annular shoulder 10d of the tubular member 10 for positioning the tubular members 10 and 20 with respect to each other in the connected position.

As illustrated in greater detail in FIG. 5, a plurality of three windows or apertures 24h are formed through the sleeve 24 adjacent the thread 10e of the tubular member 10. The inner sleeve 24 mounts an O-ring 24i for effecting a seal with tubular member 10 between the annular shoulder 10b and the connecting threads 10e to block leakage of fluid therebetween. Mounted below the threads 10f is an O-ring 10g effecting a seal between the lower portion of the sleeve 24 and the tubular member 10 to block passage of fluid therebetween.

The safety joint S includes a lug means L for connecting the upper tubular member 20 with the lower tubular member 10. The lug means L includes a plurality of latch dogs 30 mounted in the corresponding plurality of windows 24h which are radially moveable between an inner or engaging position (FIG. 1B) for connecting or securing the tubular member 20 with the tubular member 10 and to and from an outer or free position (FIG. 3B) for enabling separation or release of the tubular member 20 from the tubular member 10. The latch dogs 30 include a tapered threaded segment or portion 30a corresponding and threadedly engaging the left hand threads 10e.

The safety joint S further includes a piston means P operably connected with the latch dogs 30 for enabling separation of the safety joint S when a predetermined pressure urges on the piston means P. The piston means P includes a piston sleeve 40 concentrically mounted about the sleeve 24, such sleeve 40 being moveable longitudinally between an upper or locking position (FIG. 2B) for retaining the latch dog threads 30a in engagement with the threads 10e, and a lower or release position (FIG. 3B) to enable the latch dogs 30 to move to the free position for effecting separation of the safety joint S. The piston sleeve 40 has a constant diameter inner surface 40a which engages a constant diameter locking outer surface 30b of a plurality of spaced annular collars 30c formed on the latch dogs 30 when the piston sleeve 40 is in the locking position. When in this position, the piston sleeve 40 locks the threads 30a of the latch dogs 30 in engagement with the threads 10e of the tubular member 10 for connecting the tubular member 10 and the tubular member 20. The inner surface 40a of the piston sleeve 40 includes a plurality of correspondingly spaced annular recesses 40b formed therein adapted to receive the annular collars 30c of the latch dogs 30 therein when the piston sleeve 40 moves to the release position which enables the latch dogs 30 to move outwardly for releasing the engagement of the threads 10e and 30a. The piston 40 carries an O-ring 40c to slideably seal between the piston sleeve 40 and the sleeve 24 adjacent the lower end of the piston sleeve 40 to block leakage of fluid therebetween. The sleeve 24 carries an O-ring 24j for slideably sealing with the piston sleeve 40 to prevent leakage of fluid therebetween above the recesses 40b.

As illustrated in FIG. 1, the piston sleeve 40 has an upwardly facing annular shoulder 40d engaging a downwardly facing annular shoulder 25a of the cap ring 25 to provide a movement stop when the piston sleeve 40 is in the locking position. The surface 40a of the piston sleeve 40 has an inwardly projecting annular collar 40e formed thereon having a downwardly facing annular shoulder 40f and an upwardly facing annular shoulder 40g. The collar 40e mounts an O-ring 40h thereon for slideably sealing the collar 40e with the sleeve 24 to prevent leakage of fluid therebetween.

The sleeve 24 has an annular shoulder 24k formed thereon above the collar 40e for receiving a ring stop member 41 between the sleeve 22 and the piston sleeve 40. The engagement of the stop ring 41 with the annular shoulder 24k blocks downwardly movement of the stop ring 41 relative to the inner sleeve 24 and the ring stop member 41 is fluted at the outer portion 41a where it engages the piston sleeve 40 to enable communication of the fluid pressure across the member 41. As illustrated, a gapped radially expansible detent ring 42 having a tapered upper surface 42a is positioned immediately above the ring 41 and an annular recess 40i having a tapered upper portion 40j corresponding to the tapered surface 42a is formed in the surface 40a of the sleeve 40.

The detent ring 42 engages the tapered portion 40j to block or resist inadvertent downwardly movement of the piston sleeve 40 from the locked position to the release position. When the predetermined pressure for operating the piston sleeve 40 is applied, the tapered portion 40j will cam or wedge the detent ring 42 from the recess 40i to enable the piston sleeve 40 to move to the release position. A latch ring 43 is positioned between the piston sleeve 40 and the tubular member 24 above the stop ring 41 and carries a pair of O-rings 43a and 43b for slideably sealing the longitudinally moveable latch ring 43 with the piston sleeve 40 and the sleeve 24, respectively. The latch ring 43 includes an upwardly facing pressure responsive annular shoulder surface 43c and a downwardly facing pressure responsive shoulder surface 43d with the pressure responsive surface 43c communicating with the pressure adjacent the exterior surface 22f of the outer sleeve 22 through the port 22e. The latch ring 43 moves in response to the differential pressure urgings thereon between a lower position (FIG. 1A) and an upper position (FIG. 3A). The pressure responsive surface 43d has a ring-shaped extension 43e extending downwardly therefrom which fits within the detent ring 42 when the detent ring 42 expands into the recess 40i to block inadvertent movement of the detent ring 42 from the recess 40i. The extension 43c has a flow port 43f formed therethrough to enable communication of fluid pressure to the pressure responsive surface 43d.

The latch ring 43 includes an annular recess 43g formed adjacent the cap ring 25 which aligns with a gapped radial expansible snap ring 44 carried on the surface 22a of the sleeve 22 chich contracts into the recessed 43f when aligned therewith. The recess 43g and the snap ring 44 are provided with square shoulders in order that the snap ring 44 will not be wedged out of the recess 43f to free the latch ring. By securing the latch ring 43 in the upper position in this manner, the latch ring 43 will not drop down to re-lock the detent ring 42 in the recess 40i with the downwardly extending extension 43e or otherwise interfere with the release of the safety joint S. The operation of the detent ring 42 and the snap ring 44 block inadvertent release and insure positive release of the safety joint S, respectively.

The piston sleeve 40, the sleeve 22 and the tubular member 10 are also secured together by a threaded shear pin 50 to block inadvertent or undesired separation of the safety joint S.

The concentric spaced relationship of the piston sleeve 40 and the sleeve 22 adjacent the collar 40e forms a first annular expansible chamber 60 between the seals effected by the O-rings 40h and 24j below the downwardly facing annular shoulder 40f. The piston sleeve 40 and the sleeve 22 also form an expansible annular chamber 61 in the space therebetween sealed by the O-rings 40h, 43a and 43b above the upwardly facing annular shoulder 40d of the piston sleeve 40. Fluid pressure in the chamber 60 will urge on the pressure responsive surface 40f to urge movement of the piston means 40 upwardly to the locking position with the shoulder 40d in engagement with the cap ring 28. The pressure of the fluid in the annular expansible chamber 61 urges on the pressure responsive surface 40g to urge downwardly movement of the piston 40 to the release position and on the surface 43d of the latch 43 to urge movement of the latch 43 to the upper position. The inner sleeve 24 has a pair of flow ports, 24m and 24n formed therethrough for communicating the pressure in the bore 20a into the chambers 60 and 61 respectively. By having the pressure responsive surfaces 40f and 40g of the piston 40 of the same effective surface area, the piston will have offsetting pressure urging thereon in normal operation and will remain in the locked position until it is desired to apply the predetermined pressure for effecting movement of the piston sleeve 40 to the release position. One skilled in the art may vary the relative size of these areas without departing from the spirit of the present invention. The ports 24m and 24n are spaced a sufficient distance to receive a bridge plug means B therebetween for communicating a predetermined pressure through the flow port 24n while blocking its communication through the flow port 24m.

As illustrated in FIG. 3A, the bridge plug means B includes a tubular plug assembly 70 which is properly dimensioned to move freely through the bore X of the well conduit C and the bore 20a in the tubular member 20. The tubular assembly 70 has a downwardly facing annular tapered lower seating surface 70a which engages the upwardly facing annular shoulder 24f of the collar 24e to operably position the tubular unit 70 in the bore 20a. The tubular assembly 70 mounts a set of chevron packing 70c to effect a seal with the surface 24d of the sleeve 24 to block leakage of fluid therebetween. When the tubular unit 70 is operably positioned by the seating shoulder 70a, the packing 70c effects the seal with the surface 24d between the spaced flow ports 24m and 24n. Thus, the tubular plug assembly 70 when operably positioned in the bore 20a enables communication of the port 24n with the bore 20a and the bore X of the conduit C above the assembly 70 while blocking communication of this area with the port 24m. The tubular unit 70 has a flow port 70d formed therein adjacent the port 24m for communicating the flow port 24m with a bore 70e of the tubular plug assembly 70. The flow port 70d enables the venting or exhausting of the expansible chamber 60 into the bore 20a of the tubular member 20 below the plug assembly 70 when the piston 40 moves to the release position. The tubular plug assembly 70 includes a fishing neck 70f moveably secured thereto to enable retrieval of the plug assembly 70 when desired by a fishing operation. The fishing neck 70f is normally urged by a spring 70g to block communication through the bore 70e but which moves to vent through the assembly 70 when retrieving the assembly 70 by the fishing operation as is well known in the art.

As illustrated in FIG. 4, a reconnection tool 80 provides a means for connecting the tubular member 10 with the well conduit C above the tubular member 10 after release of the safety joint S is effected. The reconnection tool 80 is provided with the standard threaded box connection (not illustrated) for connecting the tool 80 with the well conduit C above the tool 80. The reconnection tool 80 has a positioning skirt 80a properly dimensioned to center the tool 80 in the well to center and align the tool 80, with the threads 10f of the tubular member 10. Right-hand rotation of the conduit C and reconnection tool 80 will then reconnect the well conduit C by engaging right-hand threads 80b with the threads 10f. The right-hand rotation to connect is preferred in that it eliminates the possibility of a threaded well conduit C connection becoming disengaged during employment of the reconnection tool 80. The reconnection tool 80 carries an O-ring 80c in a recess formed therein to seal with the tubular member 10 adjacent the annular shoulder 10d to block leakage of fluid therebetween when the threads 80b and 10f are fully engaged. The reconnection tool 80 has a bore 80d therethrough aligned with the bore X of the well conduit C and the bore 10a of the tubular member 10 to enable production of hydrocarbons and the like therethrough.

In the use and operation of the present invention, the safety joint S is prepared for use in a well by assembling the joint S in the condition illustrated in the FIGS. 1A and 1B. The piston sleeve 40 is in the dog 30 locking position and secured therein by the detent ring 43 and the latch ring extension 43e as well as by the shear pin 50. The threaded portions 30a of the dogs 30 engage the threads 10e of the tubular member to connect the tubular members 10 and 20 of the safety joint S. The safety joint S is connected in the well conduit C at any desired location using the threaded pin 11 and box 21 connections as is well known in the art. When connected in the well conduit C, the safety joint enables the flow of hydrocarbons and the like through the bore X of the well conduit C from a producing formation to the wall head.

When it is desired to remove a portion of the well conduit C, above the safety joint S, the positive release of the safety joint S may be effected in either of two alternate ways. The preferable mode is hydraulic release in that rotation of the well conduit C above the safety joint S is not required to effect release thereby reducing the likelihood of damage to non-concentric tools connected in the well conduit C, and safety valve control lines. To effect hydraulic release, the tubular plug assembly 70 is positioned in the bore X of the well conduit C at the surface and allowed to flow, drop, fall or otherwise move down the bore X of the conduit C until it engages the seating shoulder 24f of the sleeve 24 with the seating shoulder 70a to operably position the tubular plug assembly 70 in the bore 20a. By connecting a pump or other pressure generating means to the bore X of the well conduit C at the surface, the pressure in the bore 20a above the plug may be increased to any desired predetermined value. The plug assembly 70 enables the pressure in the bore 20a above the plug 70 to be communicated through the port 24n into the annular expansible chamber 61 while blocking the communication of this pressure through the flow port 24m into the chamber 60.

The predetermined pressure communicated into the chamber 61 urging on the surface 43d for urging the latch ring 43 to move upwardly is greater than the pressure communicated through the port 22e urging on the surface 43c for urging movement of the latch ring 43 downwardly, hence the latch ring 43 will move to the upper position. When the recess 43f of the latch ring is aligned with the snap ring 44, the snap ring will contract into the recess 43f to maintain the latch ring 43 in the upper position. The upwardly movement of the latch ring 43 moves the detent locking extension 43e from within the detent ring 42 to release the detent 42. When the recess 43g of the latch 43 aligns with the snap ring 44, the snap ring 44 will contract to move into the recess 43g for holding the latch 43 in the upper position.

The pressure in the chamber 61 also urges downwardly on the upwardly facing pressure responsive surface 40g of the piston sleeve 40 for effecting movement of the piston sleeve downwardly to the release position. Since the increased pressure in the bore 20a above the plug assembly 70 is not urging upwardly on the pressure responsive surface 40f for urging the position to move upwardly to the lock position, downward movement of the piston sleeve 40 to the released position will be effected by the predetermined pressure. As the piston sleeve 40 commences to move downwardly, the detent ring 42 will be wedged inwardly by the tapered edge 40j of the recess 40i to enable the piston sleeve 40 to move downwardly. The shear pin 50 will also be sheared by the initial pressure responsive movement of the piston sleeve 40. The piston sleeve 40 will continue to move downwardly until the O-ring 40h no longer effects a seal with the sleeve 22 and communication between the chambers 60 and 61 is thus enabled and which results in an equalization of pressure about the plug assembly 70. This pressure equalization effects a pressure drop monitorable at the surface to indicate to the operator that positive hydraulic release has been effected by the movement of the piston to the release position.

The movement of the piston sleeve 40 to the release position aligns the annular recesses 40b with the locking collars 30c of the latch dogs 30. When the well conduit C above the joint is manipulated by pulling upwardly, the taper of the engaged threads 30a and 10e will wedge or cam the latch dogs 30 outwardly to effect a release or separation of the upper tubular member 20 from the lower tubular member 10.

Should the hydraulic release not operate for any reason, release of the safety joint S can still be effected by manipulating the well conduit C. By rotating the well conduit C in a right-hand direction, the left-hand engagement of the threads 30a and the threads 10e will be disengaged. The initial rotation will shear the shear pin 50 between the sleeve 22 and the tubular member 10. While the right-hand rotation for release is preferred in that the threaded well conduit C connections will not be disengaged, the rotation of the well conduit C may damage the connected well tools and is thus employed as a back-up only when the hydraulic pressure release cannot be effected.

After separation of the safety joint S has been accomplished, the well conduit C may be connected with the upper end of the tubular member 10 by the use of the tool 80. The tool 80 is secured to the lower end of the wall conduit C and lowered down the well until the tool 80 engages the threads 10f of the tubular member 10. Right-hand rotation of the well conduit C and the reconnection tool 80 will engage the threads 80b and 10f for connecting the tubular member 10 with the tool 80. Thereafter, the well may be produced through the aligned and communicating boxes X, 10a and 80d as is well known in the art.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

Claims

What is claimed is:

1. A safety joint for well conduits, including:

a. a first tubular member having a bore therethrough adapted for connection at a first end to a well conduit and having a surface with a locking recess formed therein;

b. a second tubular member having a bore therethrough adapted for connection at a first end to another section of the well conduit with said bores of said first tubular member and said second tubular member communicating therebetween;

c. lug means mounted with said second tubular member for movement relative to said second tubular member to an engaging position within said locking recess for connecting said first and said second tubular members and to a free position spaced from said locking recess enabling separation of said first and said second tubular member;

d. piston means operably connected with said lug means for movement to a locking position to retain said lug means in said locking recess and to a release position enabling said lug means to move to said free position, said piston means moving to the release position when a predetermined pressure urges thereon; and

e. means operably engaging said lug means for effecting release of said lug means from said locking recess when said first and said second tubular members are rotated relative to each other wherein the safety joint is releasable by relative rotation or the urging of a predetermined fluid pressure.

2. The apparatus as set forth in claim 1, including: means with said first tubular member for connecting said first tubular member with another section of the well conduit after said second tubular member is released wherein said first tubular member is connectable to a well conduit.

3. The apparatus as set forth in claim 1 wherein said means for effecting release of said lug means from said locking recess, including:

a. a helical groove formed in said first tubular member; and

b. said lug means moving along said groove when said first and said second tubular member are rotated relative to each other until said lug means moves from said locking recess wherein the safety joint is released.

4. The apparatus as set forth in claim 3, wherein:

said helical groove effecting a left-hand engagement with said lug means wherein relative right-hand rotation between said first and said second tubular members releases the safety joint.

5. The apparatus as set forth in claim 1, wherein:

said piston means having first pressure responsive surface and second pressure responsive surface, said piston means moving to the locking position in response to the pressure urging on said first pressure responsive surface and moving to the released position in response to the pressure urging on said second pressure responsive surface.

6. The apparatus as set forth in claim 5, wherein:

said first pressure responsive surface and said second pressure responsive surfaces have the same pressure urging thereon to block movement of said piston means until the predetermined pressure urges movement of the piston means to the release position.

7. The apparatus as set forth in claim 5, wherein:

a. said piston means is a sleeve concentrically mounted about said second tubular member and forming a first expansible chamber and a second expansible chamber therebetween;

b. said first pressure responsive surface forming a portion of said first expansible chamber for urging movement of said piston sleeve to the locking position in response to the pressure in said first chamber; and

c. said second pressure responsive surface forming a portion of said second expansible chamber for urging movement of said piston sleeve to the released position in response to the pressure in said second chamber wherein the piston moves to release the safety joint when the predetermined pressure is communicated into said second chamber.

8. The apparatus as set forth in claim 7, wherein:

a. said second tubular member having a first flow port and a second flow port formed therethrough in spaced relationship to receive a bridge plug therebetween;

b. said first flow port communicating said first expansible chamber with said bore of said second tubular member;

c. said second flow port communicating said second expansible chamber with said bore of said second tubular member; and

d. bridge plug means positioned in said bore of said second tubular member for communicating the presetermined pressure in said bore of said second tubular member through said second flow port while blocking communication of the predetermined pressure through said first flow port wherein the predetermined pressure urges on said second pressure responsive surface to release the safety joint.

9. The apparatus as set forth in claim 1, wherein:

movement of said piston means to the released position vents said predetermined pressure to indicate that positive release has been effected.

10. The apparatus as set forth in claim 1, wherein said lug means includes:

a plurality of moveable dogs mounted with said second tubular member for movement to and from the engaging and free positions wherein said dogs engage said recess at a plurality of locations.

11. A method of alternately effecting release of subsurface safety joint having first and second tubular members for connecting portions of a well conduit for removing a portion of the well conduit from the well, including the steps of:

lowering a bridge plug down the well conduit to a location within the safety joint;

increasing the pressure in the well conduit above the bridge plug to a predetermined pressure for urging one of the tubular members to move relative to the other tubular member to effect release of the safety joint in response to the predetermined pressure; and

rotating one of the tubular members of the safety joint relative to the other tubular member to selectively effect release of the safety joint when the urging of the predetermined pressure fails to effect release of the safety joint wherein the safety joint is released by rotation when the pressure urging fails to effect release.

12. The method as set forth in claim 11, wherein the step of rotating includes:

rotating one of the tubular members in right-hand direction to selectively effect release of the safety joint when the urging of the predetermined pressure fails to effect release of the safety joint.