US 2708100 A
Description (OCR text may contain errors)
y 0, 1955 w. N. SUTVLIFF 2,708,100
SAFETY JOINT FOR OIL WELL DRILLING STEMS Filed June 1, 1951 IN V EN TOR. [dam/.5 M fun/FF ATTOP/VEYS United Sttes Patent SAFETY JOKNT FOR 011. WELL DRILLING STEMS Wayne N. Sutliff, Bakersfield, Calif.
Application June 1, 1951, Serial No. 229,388
4 Claims. (Cl. 255-28) The present invention relates to well devices, and more particularly to a safety joint construction adapted to be incorporated in a tubular string disposed in the well bore, for the purpose of elfecting disconnection between portions of the tubular string in the event the latter becomes stuck in the well bore.
An object of the present invention is to provide an improved safety joint for a tubular well string capable of safely supporting and transmitting heavy loads, and of readily being released whenever desired under the control of the operator.
Another object of the invention is to provide a safety joint which cannot be released inadvertently during normal rotation of the tubular string attached to the safety joint, and which is capable of striking a jarring blow to release the joint whenever such release is desired by the operator.
A further object of the invention is to provide a safety joint which cannot be released so long as a pendent load is being supported on the joint, which is the normal condition encountered in well bores whenever the tubular string attached to the joint is in tension.
Yet another object of the invention is to prevent release of a safety joint unless the upper portion of the joint is first moved downwardly with respect to the lower portion.
This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.
Referring to the dawings:
Figure 1 is a longitudinal section, with parts shown in side elevation, through a safety joint, disclosed as forming part of a string of drill pipe, the parts being arranged for normal rotation of the string;
Fig. 2 is a longitudinal section through a portion the safety joint illustrated in Fig. 1;
Fig. 3 is a view similar to Fig. 2, with the parts arranged for eifecting release of the safety joint;
Fig. 4 is a cross-section taken along the line 44 on Fig. 1;
Fig. 5 is a cross-section taken along the line 5---5 on Fi 1;
Fig. 6 is a cross-section taken along the line 6-6 on Fig. 2, through the jarring portion of the safety joint, and with the parts in their normal relationship;
Fig. 7 is a view similar to Fig. 6, in which the jarring mechanism has been reversely rotated to a position of initial impact between the driving lug and driven lug.
Fig. 8 is a view similar to Fig. 7, showing the driven lug as having been moved to thereby partially unthread the collar.
Fig. 9 is a view similar to Fig. 5, showing the safety joint partially unthreaded.
The safety joint A disclosed in the drawings is adapted to connect upper and lower portions B, C of a tubular string in spaced relation. Thus, the joint includes an elongate tubular body 10 having a lower pin 11 threaded into the upper box portion of a lower joint of tubing for drill pipe C. The upper mandrel 12 of the joint is suitably secured to an upper joint of tubing or drill pipe ,B, which forms part of an upper tubular string portion running to the top of the well bore.
The tubular mandrel 12 is telescoped within the tubular body 10 and has an external groove 13 on its lower cylindrical portion for containing a suitable seal 14, such as a rubber, or rubber-like, O ring adapted to slidably seal against the cylindrical wall 15 of the tubular body. Above its cylindrical sealing surface, the body has an enlarged diameter portion 16 extending upwardly from a shoulder 17 to a plurality of internal splines or keys 18 that are adapted to be engaged by companion external splines or keys 19 formed on the lower portion of the mandrel 12. When the mandrel splines 19 are fully engaged with the internal body splines 18, the lower end of the mandrel keys 19 are disposed a substantial distance above the body shoulder 17 forming the lower end of its enlarged diameter portion 16.
The mandrel 12 is urged upwardly with respect to the body 10 by a helical compression spring 20 disposed in the cylindrical body bore, the lower end of the spring bearing upon a lower body shoulder 21 and the upper end against the lower end of the mandrel 12. This spring may exert a substantial upward force on the mandrel 12, maintaining a shoulder 22 on the mandrel and above its keys 19 in engagement with the lower end of a stop collar 23 that is detachably secured to the upper end of the body 10 by means of external threads 24 on the collar meshing with companion internal threads 25 at the upper portion of the body 10 and above its internal splines 13. The threaded connection 24,
\ 25 disclosed is right-hand and the extent of threaded movement of the stop collar 23 into the body is determined by engagement of an inclined shoulder 26 on the stop collar immediately above its threaded portion with a companion inclined upper end 10a of the body. Unscrewing of the collar 23 from the body 10 is normally prevented by one or more frangible elements 27, in the form of one or more pins extending laterally through the body and into the collar, as disclosed most clearly in Figs. 1 and 5.
When the splines 18, 19 are in engagement with each other, the mandrel 12 and body 10 cannot rotate with respect to one another. However, upon lowering of the mandrel 12 within the body 10 against the force of the compression spring 20, the external splines 19 can be disposed in the circumferentially continuous annular space 28 in the body 10, which then allows the mandrel to be rotated relative to the body to a limited extent. The limitations of such relative rotation are determined by an external driving projection or key 29 on the mandrel 12 which is engageable with an inwardly directed driving projection or key 30 formed in the collar 23 and extending longitudinally therealong. The external and internal projections 29, 30 only extend a relatively small arcuate extent around the circumference of the mandrel and col-- lar, to allow the mandrel to rotate relatively within the collar. to a substantial extent. As disclosed in the drawings, the mandrel 12 can rotate approximately 300 degrees within the collar 23.
Assuming that the safety joint A forms part of a string of drill pipe used in rotating a drill bit (not shown) at the bottom of the well bore, the drilling string normally is in tension, with the safety joint parts arranged as disclosed in Figs. 1, 2 and 5. That is, the driving mandrel splines 19 are in full bearing engagement with the companion body splines 18, the load of the lower portion of the drill string C being transmitted to the mandrel 12 through the threaded safety joint connection 24, 25', stop collar 23 and mandrel shoulder 22'. As disclosed, the jar projection 29 on the mandrel is adjacent one radial face 301) of the companion jar projection 30 on the stop collar 23. Drilling fluid can be pumped down through the tubular string B, safety joint mandrel 12 and tubr body it) for continued passage through the other drill pipe joints C to the drill bit, in the usual manner, leakage through the joint being prevented by the sealing engagement of the O ring 14 with the cylindrical surface 15 of the tubular body 10'.
Inasmuch as the splines 18, 19' are in engagement with one another during transmission of the drill .g torque between the mandrel 12 and body 10, no turning effort or torque is imposed on the threaded stop collar 23, which is positively prevented from being unscrewed from the tubular body it) by the frangible pin connection 27.
In the event the drill bit or drill pipe C below the safety joint A becomes stuck in the hole, the safety joint can be released to remove the upper portion B of the drill string from the well bore. To release the joint, the drill string is rotated in a counter-clockwise direction to an extent sutficient to twist the upper portion B of the drill pipe string and impose a torsional, spring-like characteristic therein and yet to an extent insufficient to unthread the sections of drill pipe from one another. the drill string being held at the surface, the upper portion 8 is lowered relative to the lower stuck portion C until the mandrel splines 19 clear the internal body splines 18, whereupon the lower part of portion B of the drill string, including mandrel 12, rapidly unwinds in a counter-clockwise direction, causing the driving lug 29 to strike a sharp blow against face 30a of the driven lug 3%) of collar 23 (see Fig. 7), moving the driven lug 39 and therefore collar 23 from the position shown in Fig. 7 to the position shown in Fig. 8, shearing pin 27 and at least partially unscrewing collar 23 from the tubular body 10 (see Fig. 9). The position shown in Fig. 8 is merely approximate and the collar may unthread somewhat more or less in different releasing operations. Once the safety joint is broken, in the manner described above, the upper portion of the tubular string B can be rotated to the left, the driving lug 29 engaging the driven lug 30 until the collar 23 is completely unscrewed from the threaded box 25, whereupon the drill pipe string B can be elevated to elevate the mandrel 12 from the body 10, the mandrel shoulder 22 5 engaging the lower end of the collar 23 and lifting it with it. The mandrel l2 and collar 23 can then be removed to the top of the well bore.
Although described specifically in connection with a drill string, the safety joint can be used in connection with other strings, such as fishing strings, and sucker rod strings.
It is, accordingly, apparent that a safety joint has been provided which cannot be released inadvertently during the normal transmission of torque therethrough, and with a pendant load supported from the lower portion 10 of the joint. The safety joint can only be broken or disconnected purposely upon downward telescoping of its upper portion 12 within its lower portion 10.
Having thus described my invention, what I claim and desire to secure by Letters Patent is:
1. A safety joint for connecting sections of a runningin string for introduction into a well bore comprising upper and lower joint members arranged to be secured to upper and lower sections of the string respectively, said members having end portions interengageable in telescoping relation, means upon said end portions normally Then, with preventing relative rotation of the joint members and disengageable by relative axial movement to permit such relative rotation, a collar connecting the coupling members, said collar being threaded onto one coupling member and having limited axial and rotative movement relative to the other coupling member, and driving and driven lugs upon the collar and said other coupling member, the driving lug being movable circumferentially within the collar to impart jarring impact against the driven lug by torque developed in the string for unscrewing the collar from the coupling.
2. A safety joint for connecting sections of a runningin string for introduction into a well bore comprising upper and lower joint members arranged to be secured to upper and lower sections of the string respectively, said members having end portions interengageable in telescoping relation, means upon said end portions normally preventing relative rotation of the joint members and disengageable by relative axial movement to permit such relative rotation, a collar connecting the coupling members, said collar being threaded onto one coupling member and having limited axial and rotative movement relative to the other coupling member, and driving and driven lugs upon the collar and said other coupling member, said driving lug being movable circumferentially within the collar to impart jarring impact against the driven lug by torque developed in the string for unscrewing the collar from the coupling, and a shear pin normally securing the collar against rotation and severable by the jarring impact of the driving and driven lugs.
3. A safety joint for connecting sections of a string to be run into a well bore comprising a pair of telescoping coupling members attached to the sections for connecting the same, means upon the members normally interengageable to prevent relative rotation of said members and disengageable by relative axial movement of the members to permit such rotation, spring means normally holding the coupling members in their interlocked relation; a collar slidably and rotatably connected to one member and threaded onto the other member for limiting relative axial movement of the members, and lugs upon the collar and one of the coupling members operable by torque developed in the strings to impart jarring impact to the collar for unscrewing the collar from the coupling member when the coupling members are moved axially into their rotatable relation.
4. A safety joint for connecting sections of a string to be run into a well bore comprising a pair of telescoping coupling members attached to the sections for connecting the same, means upon the members interengageable to prevent relative rotation of said members and disengageable by relative axial movement of the members to permit such rotation, spring means normally urging the coupling members into their interlocked relation, :1 collar engaging the upper coupling member and threaded into the lower coupling member and provided with shoulders engaging the coupling members for limiting relative axial movement thereof, a drive lug upon the upper coupling member, a driven lug upon the collar, the drive lug being movable circumferentially within the collar for imparting jarring impact to the driven lug when the coupling members are moved axially into relative rotatable relation, and a shear pin normally securing the collar to the lower coupling member, said pin being severable by jarring impact of the drive lug against the driven lug.
References Cited in the file of this patent UNITED STATES PATENTS 2,039,943 Wicket-sham et a1. May 5, 1936 2,039,945 Wickersham et al. May 5, 1936 2,565,547 Collins Aug. 28, 1951