Abstract:
A method and apparatus for permanently locking a shiftable valve member in a well conduit in an open position is provided by permitting a spring metal band to expand from a contracted, run-in position to a radially enlarged locking position holding the shiftable valve member in an open position. Positioning lugs are additionally provided which are operable by upward movement of a mandrel to determine whether an actuating sleeve for the shiftable valve member is properly located in its position corresponding to the closed position of the valve so that it will not interfere with the operation of the expanding lock open band member. The tool can be used with a flow tube actuated flapper valve or with other conventional valves.

Description:
BACKGROUND OF THE INVENTION 
     1. FIELD OF THE INVENTION 
     The invention relates to a method and apparatus for permanently locking a shiftable valve member, such as a flapper valve, in an open position in a well conduit. 
     2. HISTORY OF THE PRIOR ART 
     In the operation of modern oil and gas wells, it often becomes desirable to permanently lock in an open position a shiftable valve member, such as a flapper valve, which is disposed in a well conduit. This is particularly necessary when it is desired to perform various well servicing operations through the valve and it is not contemplated that the valve will again be employed in subsequent operation of the well. It has previously been disclosed that valves, including rotatable ball type valves, may be held in an open position by shifting a retainer mechanism into engagement with an operating sleeve for the valve to prevent the return of the operating sleeve and valve to a closed position. See, for example, U.S. Pat. No. 3,696,868 to Taylor, Jr. This requires incorporation in the valve actuating mechanism of the retainer mechanism and thus complicates the total cost of the shiftable valve when initially installed in the well. In many cases, this cost is unjustified because the occasion never arises for locking the shiftable valve in an open position. Furthermore, the lock open mechanism is continuously subjected to subsurface well conditions during normal operations, and may be damaged, corroded or stuck in the retracted position, preventing subsequent actuation when necessary. 
     It would be desirable, therefore, to provide a method and apparatus for effecting the retention of a shiftable valve member within a well conduit in an open position by a mechanism which is entirely separate from the valve mechanism and which can be subsequently inserted in the well conduit only when it becomes necessary to permanently lock the shiftable valve member in an open position. 
     SUMMARY OF THE INVENTION 
     This invention provides a method and apparatus for effecting the locking in an open position of a shiftable valve member, such as a flapper or ball type valve normally mounted in a well conduit. The preferred embodiment of the invention may be used with a flapper valve which is actuated in conventional fashion by a reciprocating piston type sleeve. 
     This invention provides a latch in the form of a compressed cylindrical spring which can comprise a compressed C-ring or a spiral spring. The spring band is assembled on an inserting tool and peripherally compressed thereon. The spring band is held in such compressed position by a pair of axially shiftable retaining sleeves which respectively overlie the opposite axial ends of the compressed spring. The retaining sleeves are respectively spring biased to an axial position away from the compressed spring band but are respectively held in their retaining positions by two sets of locking lugs. The locking lugs are in turn maintained in their locking positions with respect to the retaining sleeves by a mandrel which is carried by the inserting tool. 
     An intermediate sleeve is provided on the insertion tool in surrounding relationship to the mandrel which is anchored to the well conduit by a conventional releasable latch which engages a no-go shoulder provided in the well conduit above the position of the shiftable valve member. The intermediate sleeve mounts the aforementioned locking lugs. The mandrel is provided with recessed external surfaces which can be moved into alignment with the retaining lugs by upward movement of the mandrel relative to the intermediate sleeve. Upon release of the retaining lugs, the spring biased sleeves move axially apart to concurrently release both edges of the contracted locking spring band. When run-in, the insertion tool pivots the flapper valve toward its open position. Since the no-go shoulder positions the spring band radially adjacent the shiftable valve member, such as a flapper valve, the locking spring band expands peripherally and forces the shiftable valve member outwardly to its outermost position, thus locking it in an open position without significantly reducing the internal fluid flow conduit. The insertion tool can then be released by conventional manipulation of the latch from the no-go shoulder, and removed from the well conduit so that the insertion tool can be reused merely by positioning another spring locking band on the intermediate sleeve. 
     It sometimes happens when an attempt is made to achieve the locking of the shuttle valve in its open position, that the actuating sleeve for the shuttle valve may be in its valve opening position, so that the release of the spring band would merely effect the engagement of the band with the interior of the actuating sleeve. To prevent this occurrence, a second set of radially shiftable positioning lugs are mounted in the intermediate sleeve for alignment just below the lower edge of the actuating sleeve when it is properly disposed in its closed position relative to the shiftable valve. The mandrel is provided with radially raised surfaces to engage the feeler lugs and thrust them outwardly at the beginning of the upward movement of the mandrel. If the actuating sleeve is in an improper position, the lugs will strike the bore of the sleeve and further upward movement of the mandrel will be prevented. A shear pin is provided between two axially connected components of the mandrel which will release under these conditions, and upon pulling the released portions of the insertion tool to the surface, the operator can then retrieve the remaining portions of the inserted tool and the still contracted locking spring band from the conduit. Accordingly, the faulty insertion of the locking spring band within the bore of an actuating sleeve is effectively prevented. 
     Further advantages of this invention will be readily apparent to those skilled in the art from the following detailed description, taken in conjunction with the annexed sheets of drawings, on which is shown a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B collectively represent a vertical quarter-sectional view of a well tool incorporating a flapper type safety valve, shown with a lock open tool disposed in a run-in position in alignment with the shiftable flapper valve. 
     FIGS. 2A and 2B collectively constitute an enlarged scale sectional view of a portion of FIGS. 1A and 1B. 
     FIGS. 3A and 3B are views respectively similar to FIGS. 2A and 2B with the operative portions of the well insertion tool shown in the positions occupied during the initial upward movement of the mandrel to effect the outward displacement of the positioning lugs. 
     FIGS. 4A and 4B are respectively views similar to FIGS. 3A and 3B but showing the position of the elements following additional upward movement of the mandrel sufficient to release the locking lugs from the spiral retaining sleeves, permitting the contracted locking spring band to expand into engagement with the flapper valve to hold such valve in an open position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1A-1B, numeral 1 indicates a conventional safety valve incorporating a shiftably mounted valve element, which in this instance comprises a flapper valve 2 which is transversely pivotally mounted in the safety valve 1 to cooperate with an annular, downwardly facing seating surface 1a. Flapper valve 2 is spring urged to its closed position and thus provides a barrier to pressured fluid flow from beneath the valve upwardly through the safety valve to the surface. 
     The safety valve assemblage 1 is further provided with an actuating sleeve 3 which is operated by conventional annular piston means (now shown) from a source of control fluid pressure (not shown) to move downwardly and effect the shifting of the flapper valve 2 about its pivot pin 2a to its open position relative to the conduit bore. In all of the drawings, the actuating sleeve 3 is shown in its position corresponding to the closing of the flapper valve 2, although it should be recognized that in the event of failure of the fluid pressure actuating system for the sleeve 3, or the return spring conventionally provided therefor, it is possible that the actuating sleeve may be disposed in a fully downward or partially downward position relative to the flapper valve 2 and thus be disposed radially adjacent to the flapper valve 2. 
     A lock open device embodying this invention comprises a cylindrical band of spring metal, such as spiral spring 5, which in its operative position shown in FIG. 4B, is disposed radially adjacent to the flapper valve 2 and expanded to hold the flapper valve 2 in its substantially vertical, open position. In its expanded position, spring element 5 may constitute a C-ring. 
     The insertion of the locking spring band 5 in an operative position relative to the shiftable valve 2 is accomplished by an insertion tool assemblage 10. Such assemblage conventionally comprises an upper tubular assemblage 11 surrounding a central mandrel 20. The upper tubular assemblage 11 is provided at its upper end with threads (not shown) for conventional engagement with the lower end of a tubing string (not shown). 
     Additionally, a conventional lock mechanism 30 is mounted on the upper tubular assemblage 11. Such assemblage cooperates with an internal no-go shoulder 1b formed in the bore of the safety valve 1 and also includes a plurality of radially shiftable locking dogs 31 which are movable radially outwardly in conventional fashion to engage an annular latching recess 1c provided above the no-go shoulder 1b. The construction and operation of lock 30 is entirely conventional and hence will not be further described. In any event, the lock 30 functions to position the upper tubular assemblage 11 and all of the apparatus depending therefrom in a fixed relationship to the no-go shoulder 1b, thus assuring that the lock open valve element to be inserted in the safety valve will be properly positioned in alignment with respect to the flapper valve 2. 
     For run-in purposes, central mandrel 20 is secured to the latch assembly by suitable shear pins (not shown). The outer housing 11 of the insertion tool is threadably connected by threads 11d to the upper end of an intermediate sleeve assembly 13 which extends to the lowermost portions of the insertion tool 10. Intermediate sleeve assembly 13 is provided with two axially spaced sets of peripherally spaced apertures 13a for shiftably mounting an equal plurality of locking lugs 14. Lugs 14 in turn cooperate with internal annular recesses 15a provided in the end of two slidable retaining sleeves 15. Locking lugs 14 are urged inwardly by a spring 14a which lies in a groove 14b provided on each lug (FIGS. 2A and 2B). 
     Upper and lower retaining sleeves 15 are axially spaced apart and have slots defining axially protruding sections 15b constructed to respectively overlap the axial ends of a peripherally contracted spiral locking spring hand 5 to permit the band to be freely inserted within the bore of the safety valve 1. The retaining sleeves 15 are divergently axially biased in a direction to release the band 5 by a compressed springs 16 which operate between internal shouder 15c provided on the respective retaining sleeve 15 and an end shoulder 13b of radially enlarged portion 13h of the intermediate sleeve assembly 13 formed by the threaded juncture of a lower sleeve extension 13k to the upper portion of sleeve assembly 13. 
     The retaining lugs 14 are held in their latching position relative to the retaining sleeves 15 respectively by radially enlarged surface portions 20a and 20b (FIGS. 2A and 2B) provided on the mandrel 20. In the run-in position of the tool 10, the enlarged portions 20a and 20b are positioned in engagement with the retaining lugs 14. Thus, a substantial upward movement of the mandrel 20 relative to the outer housing 11, and hence relative to the intermediate sleeve assembly 13, will move the enlarged mandrel portions 20a and 20b out of engagement with the inner surfaces of the retaining lugs 14, permitting such lugs to fall into radial recesses 20c and 20d respectively provided on the mandrel 20, and thus release the retaining sleeves 15 for movement under the bias of springs 16 to an axially spaced apart position, thus releasing the ends of the contracted spiral spring band 5 and permitting it to peripherally expand to the position shown in FIG. 4B wherein the flapper valve 2 is held snugly in its outermost, vertical position. One or more alignment screws (not shown) affixed to intermediate sleeves 13 above and below spring element 5 extend through the slots defining axially protruding sections 15b on retainer sleeves 15 to maintain rotational alignment during movement of retaining sleeves 15. The alignment screws are angularly displaced from the sectional views depicted herein and therefore do not appear. 
     The spring induce axial movements of the retaining sleeves 15 are respectively limited by stop sleeves 22 and 23 which are respectively threadably secured to threaded portions 13f and 13g provided on the intermediate sleeve 13. 
     In their extreme positions, illustrated in FIG. 4A, the retaining sleeves 15 respectively abut the stop sleeves 22 and 23 and, in that position, an internal recessed bore surface portion 15d of each retaining sleeve 15 overlies the locking lugs 14, thus assuring that such lugs are retained in the assemblage during the subsequent retrieval of the insertion tool assemblage 10. 
     The insertion tool 10 can than be removed from the safety valve 1 and the shiftable valve element 2 of the safety valve 1 will be permanently locked in its open position by the expanded spring band 5, without in any manner restricting the flow passage through the safety valve. 
     In order to prevent the release of the spirally contracted locking band 5 when the actuating sleeve 3 is in its proper position, namely, radially adjacent to the flapper valve 2, a plurality of positioning lugs 17 are provided which are radially slidably mounted in the enlarged portion 13h of the intermediate sleeve assembly 13. The positioning lugs 17 cooperate with a radially enlarged surfaces 20e provided on the mandrel 20 and are shifted outwardly by such radially enlarged surface by upward movement of the mandrel 20 prior to the recessed surfaces 20c and 20d being positioned to receive the retaining lugs 14. Lugs 17 are positioned within slots defined between axially protruding sections 15b on retaining sleeve 15. 
     In normal use, the run-in tool is lowered into the well to open the valve 2, with the valve actuating sleeve 3 remaining in its unactuated upper position. In the event that the actuating sleeve 3 is in an improper position radially adjacent to the path of expansion of the spiral locking band 5, the positioning lugs 17 will abut the inner surface of the actuating sleeve 3 and prevent any further upward movement of the lower portion of the mandrel 20. Additional sets of positioning lugs similar to lugs 17 can be located at other axial positions on the lock-open tool. For example, positioning lugs may be located immediately below the spring element 5. Of course cooperable recesses and radially enlarged surfaces must be added to the mandrel. These additional axial sets may be added to insure that positioning lugs at a single axial location do not expand at an unanticipated position on the bore of the conduit into unanticipated radial opening. 
     A shear pin 25 is provided between upper and lower portions of mandrel 20 to permit the separation of the mandrel in the event that the positioning lugs 17 cannot be advanced outwardly. Thus, when the severed insertion tool 10 is returned to the surface, the operator will know immediately that the actuating sleeve 3 was improperly positioned, hence, the lower portions of the mandrel 20 remaining in the well conduit can be retrieved in conventional fashion, and proper steps taken to effect the correct positioning of the actuating sleeve 3 prior to reinserting the insertion tool and releasing the expandable locking band. 
     From the foregoing description, it is apparent that provision must be made for relative upward movement of the mandrel 20 with respect to the outer housing 11. This may be provided in conventional fashion through the utilization of a wireline or a fluid pressure actuator for the mandrel 20. 
     It will be readily apparent to those skilled in the art that the method employed in the aforedescribed procedure has many applications beyond that of inserting a locking band to hold a flapper valve in an open position. Broadly speaking, the method can be employed to insert a peripherally expandable band into any desired location within the bore of a well conduit or well tool. The same sequence of steps is employed, namely, the peripherally expandable spring band is wound or peripherally contracted about a run-in tool which includes an axially shiftable mandrel. The edges of the contracted expandable band are secured by shiftable latches. The latches in turn are shiftable to a disengagable position by axial movement of the mandrel. Thus, the contracted band may be run into the bore of a well conduit, positioned wherever desired, and release of the expandable band to expand outwardly against the walls of the conduit accomplished by axial movement of the mandrel. Thereafter, the remaining portion of hte tool may be removed from the well bore. 
     Although the invention has been described in terms of specified embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necesasarily limited thereto, since alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.