US 3470951 A
Description (OCR text may contain errors)
United States Patent US. Cl. 166-237 3 Claims ABSTRACT OF THE DISCLOSURE The particular embodiment disclosed herein as illustrative of one form of the invention is a selectively operable coupling device for controlling relative movement between telescoping members in a well tool including a segmental nut member between said members and arranged for lateral movement, means for securing said nut member against rotation relative to one of said members, spaced upper and lower thread portions on said nut member having opposite lead threads, and spaced upper and lower companion threads on the other of said members respectively engageable with threaded portions on said nut member to prevent relative movement, and releasable therefrom to permit relative movement in response to rotation of one of said members relative to the other in one rotational direction.
The present invention relates generally to well tools, and more specifically to a selectively manipulatable device for controlling relative movement between parts of a well tool.
Many well tools have expansible elements such as slips and packing which are expanded in a well conduit in response to manipulation of a running-in string of tubing or drill pipe extending from the tool to the earths surface. Since the tool must first be moved through the well conduit to a predetermined depth of setting, it is desirable to prevent any premature expansion or operation of parts during lowering. This necessitates the use of a control device which can lock the tool parts against relative movement during lowering and which can be manipulated at setting depth from locked to released condition. Moreover, once the tool is set, it may be desirable to lock the various parts in set condition so that the tool will remain set in the well conduit until it is desired to remove it. Accordingly, the control mechanism should have the further capability of again locking the various parts against relative movement in set positions. Then at some later time it may be desirable to remove the tool of the well conduit, whereupon the control mechanism should be manipulatable to a released condition to permit relative movement to occur in retracting the slips and packing. Finally, it is usually desirable to again lock the various parts in their initial retracted relative position for longitudinal movement in the well conduit.
The motions which normally can be applied to the running-in string at the earths surface to operate such a control device are rotational motion in either direction and/ or vertical motion, either upward or downward. One control device which is responsive to these manipulations and has the above-mentioned capabilities is the so-called clutch nut or dizzy nut system which comprises an expansible and contractable nut member having threads which are cooperable with mating threads on a mandrel to prevent relative movement when engaged, and which are releasable by relative rotation to permit longitudinal relative movement. Then the threads can be reengaged by vertical movement without rotation due to the one-way ratcheting characteristics of the device.
In the prior art, several diiferent structural arrangements have been used. For example, US. Patent No. 3,279,542 issued to Brown shows separate upper and lower clutch nuts which are alternatively engageable with spaced mandrel threads. This system may function quite effectively, but has the disadvantage that its use necessitates a rather lengthy slip cage, with consequent increase in manufacturing costs and loss of tool compactness. Another clutch nut arrangement is used in the well tool illustrated in the Oilfield Composite Catalog, l96667, on page 552, wherein a single clutch nut has alternate segments with reverse lead threads which are respectively alternatively engageable with spaced mandrel threads. This system has the disadvantage that the threads are in engagement only around one-half the thread circumference, resulting in poor load distribution and structural weakness. Still another clutch nut arrangement is shown in US. Patent No. 2,893,492 issued to Brown wherein each clutch nut segment has reverse lead threads which are alternatively engageable with spaced reverse lead mandrel threads. This nut configuration is quite diflicult to machine and the thread forms are structurally weak, particularly at points where the thread forms intersect each other.
The present invention is directed to a new and improved clutch nut arrangement which is cooperable with spaced, reverse lead thread sections on a mandrel to enable selective locking of the mandrel in various longitudinal positions relative to an outer tubular member, as well as selective release from locked condition for longitudinal movement between locked positions. Only a single clutch nut assembly is used so that the system is compact to reduce manufacturing costs. The nut assembly has longitudinally spaced threads to enable full circle engagement with respective mandrel threads. Thus, loads are evenly distributed between threads to enhance the strength and load bearing characteristics of the system. The respective thread sections are not coextensive, so that the nut assembly is easily manufactured.
The present invention may be summarized from a conceptual standpoint as a releasable coupling device for use in a well tool to control relative movement between tubular telescoping members. The coupling device includes radially movable, inwardly biased means between said members having longitudinally spaced threaded portions which are respectively engageable with spaced threaded portions on one of said members. Means are provided for preventing relative rotation between said means and the other of said members. The respective threaded portions are constructed and arranged to be engaged with one another in response to longitudinal relative movement without rotation, and to be disengaged only in response to relative rotation, preferably in response to rotation in the same hand direction.
The present invention has other concepts and advantages which will become more clearly apparent in connection with the following detailed description. A preferred embodiment is shown in the accompanying drawings, in which:
FIGURE 1 is a somewhat schematic cross-sectional view, with portions in side elevation, of a well tool which embodies the principles of the present invention;
FIGURE 2 is an enlarged fragmentary cross-section view of the present invention to show further structural details thereof; and
FIGURE 3, is a sectional view of the clutch nut assembly of FIGURE 2.
Referring initially to FIGURE 1, the present invention is illustrated in connection with a well tool 10 for use in a well bore. The well tool 10, although shown in a bridge plug form, can be any type of well device where it is desirable to lock an inner tubular member, such as a central body or mandrel, in more than one longitudinal position relative to an outer tubular member, such as a slip cage. One of the relative positions may correspond to the running-in condition of the tool where slips and packing are retracted. In the other relative positions, the slips and the packing may be expanded into respective gripping and sealing engagement with a well conduit wall.
The well tool is shown as comprising a central mandrel 11 having a blind bore 12 and side ports 13 which can be opened and closed by a valve sleeve 14. A connector head 15 on the upper end of the mandrel 11 has a slot system 16 to provide a means for releasably connecting the mandrel to a running-in string of drill pipe or tubing (not shown). The mandrel 11 is rotatively coupled to a compression sleeve member 18 by an annular shoulder 19 which engages within a recess 20 in the sleeve member. An elastomeric packing element 22 is mounted around the sleeve member 18 with its upper end engaging an annular abutment 23 on the sleeve member. A lower annular abutment 24 is slidable on the sleeve member 18 and engages the lower end of the packing element. Thus the packing element 22 may be compressed and expanded in response to movement of the abutmcnts 23 and 24 relatively toward each other. A suitable seal ring 21 can be provided for preventing fluid leakage between the sleeve member 18 and the mandrel 11.
The lower abutment 24 may be supported by a sleeve 25 which is connected to an expander cone 26 having downward and inwardly inclined outer surfaces 27. The expander cone 26 can be coupled against rotation relative to the compression sleeve 18 by coengaging splines 28 or the like. Coengageable shoulders 29 and 30 are provided to limit downward movement of the expander cone 26 relative to the compression sleeve 18.
A tubular cage member 32 is movably mounted on the lower end portion of the mandrel 11 above an annular stop ring 33 which limits downward movement of the cage member relative to the mandrel. A plurality of conventional drag blocks 34 are carried by the cage member 32 and are urged outwardly by coil springs 35 or the like. Moreover, a plurality of slip elements 36 are pivotally connected to the upper end of the cage member 32 by reins 37, the slip members having wickers or teeth 38 on their outer faces as well as inner inclined surfaces 39 which are companion in shape to the expander cone surfaces 27. Thus the slip elements 36 can be shifted outwardly into gripping engagement with a well conduit wall by downward movement of the expander cone 26 relative to the slip elements, and a conventional dove-tail tongue and groove connection 40 can be provided to effect inward retraction of the slip elements upon upward movement of the expander cone 26 relative to the cage member 32.
A clutch nut assembly 42 in accordance with the present invention is provided to enable selective control over relative movement between the mandrel 11 and the cage member 32. With particular reference to the somewhat enlarged drawing FIGURES 2 and 3, the clutch nut assembly 42 comprises an annular member 43 which is radially cut into a plurality of segments 44, for example, four. The nut member 43 is received within an annular recess 45 which is somewhat enlarged relative to the nut member to accommodate lateral expansion and contraction of the segments 44. Upper and lower resilient members such as band springs 46 and 47 are received within respective grooves in the segments and encompass the nut member 43. Thus the segments 44 can expand and contract laterally while being constantly urged inwardly by the band springs 46 and 47. Relative rotation between the various segments 44 and the cage member 32 can be prevented by lugs 48 projecting inwardly into vertically extending slots 49 formed in the periphery of each segment. The upper and lower walls of the recess 45 can be formed as oppositely inclined surfaces 50 and 51, which are shaped for engagement with upper and lower inclined end surfaces 52 and 53 on the respective nut segments 44.
Each segment 44 has spaced upper and lower threaded sections with teeth 55 and 56 of the buttress type having transverse surfaces facing respectively downwardly and upwardly. The upper threads 55 are of a relatively finethread construction and are formed on a left-hand helix, while the lower threads 56 are relatively coarse and are formed on a right-hand helix. The lower threads 56 are formed to have a through bore size which is at least as great as the root diameter of the upper threads 55.
The mandrel 11 is formed to have spaced upper and lower threaded portions 57 and 58, the upper threads 59 being companion in shape and size to the upper segment threads 55 and the lower threads 60 being companion in shape and size to the lower segment threads 56. Thus the upper threads 59 have transverse surfaces facing upwardly and are left-hand threads, while the lower threads 60 have transverse surfaces facing downwardly and are right-hand threads. The lower mandrel threads 60 can be formed over a vertical extent approximately equal to the vertical extent of the lower segment threads 56, while the upper mandrel threads 59 can be formed over a significantly greater peripheral extent of the mandrel 11. Thus the lower mandrel and segment threads 60 and 56 may have a single relative point of engagement, while the upper mandrel and segment threads 59 and 55 can be engaged over a relatively wide range of relative positions of the mandrel 11 and the cage member 32. Due to the formation of the various threads, the lower mandrel threads 60 can be screwed downwardly and disengaged from the lower segment threads 56 in response to righthand rotation of the mandrel; continued downward mandrel movement without rotation will cause the upper mandrel threads 59 to ratchet through and engage the upper segment threads 55. In like manner, right-hand rotation of the mandrel 11 can cause the upper mandrel threads 59 to screw upwardly out of engagement with the upper segment threads 55. Continued upward mandrel movement without rotation will cause the lower mandrel threads 60 to ratchet back into engagement with the lower segment threads 56.
OPERATION The present invention can be assembled as shown in the drawings and lowered into a well conduit with the mandrel 11 coupled to a running-in string of tubing or drill pipe. The drag blocks 34 frictionally engage the inner conduit wall to yieldably resist movement in a conventional manner. The mandrel 11 is extended relative to the slip cage 32, and the slips 36 and packing element 22 are in normally retracted positions. The lower mandrel threads 60 engage the lower threads 56 of the nut segment 44 to prevent upward movement of the cage member 32 relative to the mandrel 11, thus preventing upward movement of the slips 36 toward the expander cone 26 during downward shifting of the tool to setting depth. Inasmuch as the slips 36 cannot move toward the expander cone 26, or vice versa, the slips cannot be inadvertently shifted into gripping engagement with the well conduit during lowering.
When it is desired to set the tool, of course the tool is halted, and then the mandrel 11 is rotated by the running-in string to the right. If desired, such right-hand rotation can be accompanied with a small amount of further lowering movement of the mandrel 11. The drag blocks 34 will prevent rotation of the cage member 32, and since the nut segments 44 cannot rotate relative to the cage member due to engagement of the lugs 48 within the slots 49, it will be appreciated that the lower mandrel threads 60 will be screwed downwardly and out of engagement with the lower segment threads 56, thereby enabling downward movement of the mandrel 11 relative to the cage member 32 without further rotation. The coarse construction of the threads 56 and 60 enables release in response to only a very few turns of the runningin string. Such downward movement will effect expansion of the slips 36 into gripping and supporting engagement with the well conduit, whereupon the weight of the running-in string may be imposed upon the mandrel 11 to compress and expand the packing element 22. As the mandrel 11 is thus moved downwardly, the relatively fine upper mandrel threads 59 will ratchet through the companion upper segment threads 55 due to the camming action of the lower thread faces against corresponding faces on the segment threads, and to the ability of the segments to expand and contract laterally while being constanly urged inwardly by the band springs 46 and 47. Inasmuch as the bore through the lower segment threads 56 is at least as large as the root diameter of the upper mandrel threads 55, the upper mandrel threads can readily pass downwardly through the lower segment threads 56 without interference. Due to the upwardly and downwardly facing form of the respective mandrel and segment threads 59 and 55, it will be apparent that the mandrel 11 will become trapped in the lowermost position to which it is moved relative to the cage member 32 to trap compression loading in the packing element 22 and thereby lock the tool in set condition. The fine-thread construction of the threads 55 and 59 enables efiicient trapping of the compression loading in the packing element 22 because the relatively small pitch of these threads ensures that all or practically all of the downward movement of the mandrel to be retained by the clutch nut assembly 42. The upper mandrel threads 59 can have a considerable vertical extent to accommodate a wide range of relative movement requirements for expanding the slips 26 and the packing element 22.
With the tool locked in set condition, it will remain until it is desired to remove it from the well. Removal of the tool may be accomplished by rotating the mandrel 11, again to the right, relative to the cage member 32. By virtue of the left-hand formation of the threads 59 and 55, right-hand rotation of the mandrel will result in upward feeding of the mandrel relative to the cage member. Such right-hand rotation may be accompanied by upward strain on the running-in string if desired. Upward movement of the mandrel 11 relative to the cage member 32 will effect release of compressive force on the packing element 22, which will inherently retract, and eventual upward movement of the expander cone 26 relative to the slips 26, causing the latter to shift inwardly to retracted positions. Upward movement of the mandrel 11 can be continued until the lower end surface of the cage member 32 shoulders against the gauge ring stop 33, at which point the lower mandrel threads 60 will have ratcheted back into engagement with the lower segment threads 56. Accordingly, the cage member 32 is again secured against longitudinal movement relative to the mandrel 11, and the tool can be retrieved from the well or moved to another setting position.
Since only one clutch nut assembly 42 is utilized in accordance with the present invention, the overall length of the cage member 32 can be relatively short to increase the compactness of the tool and reduce manufacturing costs. Since the respective upper and lower segment threads 55 and 56 extend continuously about respective inner peripheral portions of each segment 44, there is substantially full circle engagement with the mandrel threads 59 and 60 to evenly distribute the loading therebetween. Finally, since the lower segment threads 56 are sized to pass the upper mandrel threads 59 without interference, the upper mandrel and segment threads 59 and 55 can be expeditiously engaged without undue lateral ratcheting action of the segments 44 so as to obviate the problems of cocking and canting and failure to properly engage. Since certain changes or modifications may be made in the present invention without departing from the inventive concepts involved, it is the aim of the appended claims to cover all such changes and modifications falling within the true spirit and scope of the present invention.
1. In a well packer apparatus having settable packing and adapted to be releasably locked in both the running or retrieving and the set conditions in a well bore, the improvement comprising: a body member adapted for connection to a running-in string; a clutch nut assembly surrounding said body member and having a plurality of transversely aligned arcuate segments which together form a generally cylindrical structure, each segment having spaced upper and lower internal threads formed respectively in the left hand and the right hand directions; resilient means urging said segments together as a cylinder but permitting radial expansion thereof; and spaced upper and lower companion external threads on said body member engageable with respective threads on said segments by longitudinal movement without rotation and releasable from respective threads on said segments by rotation of said body member relative to said clutch nut assembly in one rotational direction, said lower threads on said segments and said body member being relatively coarse threads and asid upper threads on asid segments and said body member being relatively fine threads, said lower threads on said segments defining a through bore having a diameter which is at least as great as the root diameter of said upper threads.
2. In a well packer apparatus having settable packing and adapted to be releasably locked in both the running or retrieving and the set conditions in a Well bore, the improvement comprising: a clutch nut assembly having a plurality of transversely aligned arcuate segments which together form a generally cylindrical structure, each segment having spaced upper and lower internal threads formed respectively in the left and the right hand directions, said lower threads being relatively coarse threads and said upper threads being relatively fine threads, said clutch nut assembly including resilient means for urging said segments together as a cylinder but permitting radial expansion thereof.
3. The apparatus of claim 2 wherein said upper and lower threads are formed on difierent diameter, said lower threads defining a through bore having a diameter which is at least as great as the root diameter of said upper threads.
References Cited UNITED STATES PATENTS 2,831,542 4/1958 Lynes et a1. 166-237 X 2,893,492 7/1959 Brown 166-119 3,279,542 10/1966 Brown 166-139 3,288,219 11/1966 Young et a1. 166-134 X 3,311,173 3/1967 Henslee et al. 166 15O 3,385,365 5/1968 Young 166-123 X 3,294,172 12/1966 Brown 166-139 DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 166-123, 139, 182