Latch for releasably locking a flow control device in the pocket of a well mandrel
United States Patent [191 McGowen, Jr. deceased et al.  
 [ Apr. 1,1975  
 [ LATCH FOR RELEASABLY LOCKING A FLOW CONTROL DEVICE IN THE POCKET OF A WELL MANDREL [76] Inventors: Harold E. McGowen, Jr. deceased,  
 late of Houston, Tex.; Wanda Elizabeth Lyles McGowen, Executrix, No. 6 Huntington Cir., Longview, Tex. 75601 [22] Filed: I Mar. 29, 1974 [21] Appl. No.: 456,112  
 Primary Examiner-James A. Leppink Attorney, Agent, or Firm-Fulbright &amp; Jaworski [57] ABSTRACT A latch for releasably locking dummies and control gas lift valves in the pocket of a well mandrel in which the mandrel includes a locking shoulder above the pocket. The latch includes a stem, and a cage assembly releasably connected to the exterior of the stem. The cage assembly includes a body having a plurality of windows, and a plurality of locking lugs which are slidably positioned between the stem and the body and extend outwardly through one of the windows for engagement with the locking shoulder, and spring means for yieldably urging the lugs downwardly. The stem includes spaced apart upper and lower recesses with an outwardly extending locking surface therebetween. The windows include a lower shoulder located to position the locking lugs against the locking surface on the stem when the lugs are moved downwardly by the springs. When the latch moves past the locking shoulders, the lugs will be pushed upwardly by the locking shoulder into the upper recess allowing passage of the latch past the locking shoulder. After passing the locking shoulder, the lugs will be forced downwardly by the spring means against the lower shoulder and locked in place by the stem locking surface. Upon release of the cage from the stem, the lugs may be pushed inwardly into the lower recess for retrieval of the latch and the flow control device.  
 12 Claims, 4 Drawing Figures LATCH FOR RELEASABLY LOCKING A FLOW CONTROL DEVICE IN THE POCKET OF A WELL MANDREL BACKGROUND OF THE INVENTION Various types of latches used for securing a flow control device, such as a gas lift valve in the pocket of a well mandrel in well tubing, are shown in US. Pat. Nos. 3,074,485 and 3,471,601.  
  The present invention is directed to an improved latch which is interchangeable with the locking devices presently used having a cage assembly carrying a plurality of locking dogs which protrude outwardly through windows in the cage assembly, which is positively acting, and which does not provide free ends protruding outwardly into a well bore so as to be caught open or interfere with the operation of well equipment being moved through the tubing.  
 SUMMARY The present invention is directed to a well lock for releasably locking a flow control device in the pocket ofa well mandrel in which the mandrel includes a locking shoulder above the pocket. The latch holds the flow control device in place in the mandrel pocket and allows the flow control device to be removed and retrieved when desired.  
  The improved latch includes a stem having spaced apart upper and lower recesses on its exterior surface and having an outwardly extending locking surface therebetween. A cage assembly having a body is releasably connected, such as by a shear pin, to the exterior of the stem. The cage assembly body is connected to and supports a flow control device from the stem.  
  The cage assembly body includes a plurality of windows and a plurality of locking lugs. Each of the lugs is slidably positioned on the exterior of the stem and extends outwardly through one of the windows for engagement with the locking shoulder on the mandrel. Spring means are positioned between the body and the stem and yieldably urging the lugs downwardly.  
  Each of the windows includes a lower shoulder located to position the locking lugs against the locking surface on the stem when the lugs are moved downwardly by the spring. The latch may be moved downwardly past the mandrel locking shoulder and the lugs will be pushed upwardly into a first retracted position by contact with the locking shoulder into the upper recess on the stem allowing passage of the latch past the locking shoulder. After the lugs have moved past the locking shoulder, the lugs will be forced downwardly by the spring means against the lower window shoulder and into a second locking position and locked in place by the stem locking surface. Release of the latch is provided by releasing the cage from the stem and on upward movement of the stem relative to the cage the lugs may be pushed inwardly into a retracted position into the lower stem recess by contact with the mandrel locking shoulder for retrieval of the latch and the flow control device.  
  It is a further object of the present invention to provide locking dogs which include camming surfaces for coacting with the locking shoulder in the mandrel, but in which the free ends of the locking dogs are retained in the cage assembly and prevented from being caught on or engaging well equipment moving through the tubing bore.  
  It is still a further object to provide coacting engaging means between the stem and the cage body for supporting the cage body and the flow control unit when the shear means between the stem and the cage body is sheared.  
  Other and further features and advantages will be apparent from the following description of the preferred embodiment.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary elevational view, partly in cross section, illustrating the improved latch of the present invention is locked position in the pocket of a well mandrel,  
  FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1,  
  FIG. 3 is a fragmentary elevational view, in cross section, showing the improved latch of the present invention being inserted into the pocket of a well mandrel, and  
  FIG. 4 is a fragmentary elevational view, in cross section, illustrating the latch of the present invention being removed from the mandrel.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly to FIG. 1, the reference numeral 10 generally indicates the latch of the present invention positioned in a sidepocket mandrel 12 having a pocket 14 for receiving a flow control device 16, such as a dummy or gas lift valve, for releasably securing the valve 16 in the pocket 14 as generally described in connection with FIGS. 17 through 22 of US. Pat. No. 3,074,485. The mandrel 12 includes a locking shoulder 18, which may be arcuate or circular, for coacting with the latch 10 for releasably securing the latch 10 and thus the valve 16 in place. The setting and retrieving of the valve 16 and latch 10 may be suitably performed by conventional tools, such as those described in US. Pat. No. 3,074,485.  
  The present latch 10 includes a stem 20 having a pointed head 24 and a retrieving shoulder 25. The stem includes an upper recess 26 providing a first retracted position for locking lugs which will be more fully described hereinaft&#39;er and a spaced apart lower recess 28. An outwardly extending locking surface 30 providing a second locking position is positioned between recess 26 and 28. And a guide surface 27 is formed on the stem 20 between recess 26 and locking surface 30.  
  A cage assembly generally indicated by the reference numeral 32 is provided which includes a tubular body 34 longitudinally movable on the stem 20 but initially releasably connected to the stem 20 by suitable means such as a shear pin 36. The cage assembly 32 includes a plurality of circumferentially spaced windows 38 in the body 34 and carries a plurality of locking lugs 40. Each of the lugs 40 is slidably positioned on the exterior of the stem 20 and movable relative to the body 32 and a portion thereof extends radially outwardly through one of the windows 38 for engagement with the locking shoulder 18. Spring means 42 is positioned between the stem 20 and the body 34 and yieldably acts to urge the lugs 40 downwardly. Camming surfaces 54 and 56 are provided on the lugs 40 for coacting with camming surfaces 60 and 58, respectively, on the mandrel locking shoulder 18. Thus the lugs 40 are confined for limited movement by the body 34 to and from a first retracted position in the recess 26 for enabling movement of the flow control device 16 past the locking shoulder 18 and a second locking position against the surface 30 for engaging the locking shoulder 18 to secure the flow control device 16 in the pocket 14 of the mandrel 12.  
  Each of the windows 38 includes a lower shoulder 44 limiting the downward movement of the locking lugs 40 for positioning the locking lugs 40 against the locking surface 30 on the stem 20 for holding the locking lugs 40 in an outwardly and locked position. On the other hand, if the locking lugs 40 are positioned on either side of the locking surface 30, they may be forced into a retracted position into the recesses 26 and 28 for bypassing the mandrel locking shoulder 18 as will be more fully described hereinafter.  
  In operation, and referring to FIG. 3, the latch is connected to a suitable running tool 50 by one or more shear pins 52 and lowered, such as described in U.S.  
 . Pat. No. 3,074,485 for inserting the valve 16 into the sidepocket 14 of a mandrel 12 as inconventional. As the flow control unit 16 is inserted and moved downwardly in the pocket 14, one or more of the locking lugs 40 engages the locking shoulder 18. The camming surface 58 on the locking shoulder 18 engages the camming surface 56 on the locking lugs 40 forcing the locking lug 40 upwardly and inwardly along guide 27 into a first retracted position in the recess 26 by compressing the spring 42, allowing the latch to move downwardly past the locking shoulder 18. After the locking lugs 40 have bypassed the locking shoulder 18, the spring 42 causes the locking lugs 40 to move downwardly across guide surface 27 and radially outward to the window shoulder 44 and into a second locking position and into engagement with the stem locking surface I 30 for holding the locking lugs 40 in a position extending outwardly through the window 38 and locked as shown in FIG. 1. An upward jar may be taken on the setting tool 50 shearing the pins 52 leaving the latch 10 and flow control unit 16 in the mandrel 12. It is to be noted that the shear pins 52 shear at a lesser force than the shear pin 36.  
 Of course, any upward movement of the latch 10,  
 &#39; such as by pressure in the pocket 14, will bring the camming surface 54 on the locking dog 40 into contact with the camming surface 60 on the locking shoulder 18, but since the locking dogs 40 are held in an outward locking position by the locking surface 30, the latch 10 will not release.  
  When it is desired to remove the latch 10, a pulling tool 62, as best seen in dotted outline in FIG. 4 is moved downhole to grab the shoulder 25 of the stem 20. An upward pull by the pulling tool 64 will shear the shear pin 36 allowing the stem to be moved upwardly relative to the cage assembly 32 and locking dogs 40. A coacting shoulder 64 on the exterior surface of the stem 20 is provided to engage a coacting surface 66 on the body 32 for supporting the body 32 and flow control unit 16 after the shear pin 36 is sheared. When the coacting shoulders 64 and 66 are engaged, as best seen in FIG. 4, the recess 28 on the stem 20 is aligned with the locking dogs 40 and allows coaction between the camming surfaces 54 on the locking dog 40 and the camming surface 60 on the locking shoulder 18 to coact to push the locking dogs 40 into a retracted position in the recess 28 and upwardly past the locking shoulder 18 for releasing the latch 10 and flow control device 16.  
  The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein. While a presently preferred embodiment of the invention is given for the purpose of disclosure numerous changes in the details of construction and arrangement of parts will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention and the scope of the appended claims.  
 What is claimed is:  
  1. A latch apparatus adapted for mounting with a flow control device for releasably locking the flow control device in the pocket of a mandrel having a locking shoulder, comprising:  
 a stem;  
 body means mounted with said stem and having a plurality of windows formed therethrough;  
 a lug for each of said plurality of windows and confined for limited movement by said body means to and from a first retracted position for enabling movement of the flow control device past the looking shoulder and a second locking position for engaging the locking shoulder to secure the flow control device in the pocket of the mandrel; and  
 means for moving each of said plurality of lugs from the first retracted position to the second locking position upon longitudinal movement of said lugs past said locking shoulder.  
 2. The apparatus as set forth in claim 1, wherein:  
 said body means having a tubular portion with said windows circumferentially spaced on said tubular portion; and  
 each of said plurality of lugs moving to extend a portion thereof radially outwardly from said tubular portion through said windows in moving to the second locking position.  
 3. The apparatus as set forth in claim 2, wherein:  
 said means for moving including means for guiding movement of each of said plurality of lugs from the first retracted position to the second locking position.  
 4. The apparatus as set forth in claim 3, wherein:  
 said means ffor guiding including a guide surface formed on said stem for moving each of said plurality of lugs radially outwardly as each of said plurality of lugs move on said guide surface.  
 5. The apparatus as set forth in claim 4, wherein:  
 said guide surface connecting with a recessed surface portion on said stem for enabling movement of said plurality of lugs to the first retracted position when the lugs move along said guide surface to said recessed surface; and  
 said guide surface connecting with a locking surface portion on said stem for holding said plurality of lugs in the second locking position when said plurality of lugs move along said guide surface to engage said locking surface.  
 6. The apparatus as set forth in claim 5, wherein:  
 said means for urging movement of each of said plurality of lugs including spring means mounted with said body means and operably connected with each of said plurality of lugs for urging movement of each of said plurality of lugs along said guide surface from said recessed surface portion to said locking surface portion of said stem.  
 7. The apparatus as set forth in claim 6, wherein:  
 said spring means is yieldable to enable movement of each of said plurality of lugs to the first retracted position when said plurality of lugs engage the locking shoulder in moving into the pocket of the mandrel.  
 8. The apparatus as set forth in claim 7, wherein:  
 each of said plurality oflugs when in the second locking position engaging a shoulder formed by said window to block upward movement of said body means when the radially outwardly extending portion of said plurality of lugs engage the locking shoulder wherein movement of the flow control device from the pocket of the mandrel is blocked by the latch apparatus.  
 9. The apparatus as set forth in claim 8, wherein:  
 said locking surface portion of said stem is moved from engagement with said plurality of lugs to release said plurality of lugs for movement from the second locking position wherein the latch apparatus is released to enable movement of the flow control device from the pocket of the mandrel.  
 10. The apparatus as set forth in claim 9, wherein:  
 said stem is connected to said body means by shearable means for blocking undesired relative movement therebetween. said stem moving to release said plurality of lugs from engagement with said locking surface portion after shearing of said shearable means.  
 11. A latch for releasably locking a flow control device in the pocket of a mandrel in which the mandrel includes a locking shoulder above the pocket compris- 6 ing,  
 a stem having spaced apart upper and lower recesses on its exterior surface, and having an outwardly extending lock surface therebetween;  
 a cage assembly having a body releasably connected to the stem, said cage assembly body connected to and supporting said flow control device;  
 said cage assembly including a plurality of windows in said body and a plurality of lugs, each of said lugs slidably positioned on the exterior of the stem and extending outwardly through one of said windows for engagement with the locking shoulder, and spring means positioned between the stem and said body and yieldably urging said lugs downwardly,  
 each of said windows including a lower shoulder located to position the locking lugs against the locking surface on the stem when the lugs are moved downwardly by the spring whereby when the latch is moved past the locking shoulder the lugs will be pushed upwardly by the locking shoulder into the upper recess allowing passage of the latch past the locking shoulder after which the lugs will be forced downwardly by the spring means against the lower shoulder and locked in place by the stem locking surface, and upon release of the cage from the stem, the lugs may be pushed inwardly into the lower recess for retrieval of the latch and flow control device.  
  12. The apparatus of claim 11 wherein the cage body is releasably connected to thestem by shear means and including coacting engaging means between the stem and cage body for supporting the cage assembly from the stem when the shear means is sheared.