US 3802506 A
In accordance with an illustrative embodiment of the invention disclosed herein, an apparatus for releasably latching the lower end of a tubing string in a well casing having a landing nipple therein includes laterally flexible anchors carried by a body structure and held inwardly during running. When the anchors encounter the recesses in the nipple, they resile outwardly to stop downward movement, whereupon a clutch can be released to enable the body structure to be moved downwardly to releasably lock the anchors in set position. A seal on the body structure closes the tubing-to-casing annulus so that it can be used for a pressure path to a remote controlled safety valve installed in the tubing above the latching apparatus.
Claims available in
Description (OCR text may contain errors)
[451 Apr. 9, 1974 LATCHING APPARATUS FOR INSTALLING SAFETY VALVES IN WELLS  Inventor: David E. Young, Friendswood, Tex.
 Assignee: Schlumberger Technology Corporation, New York, N.Y.
221 Filed: May 9,1973
21 Appl. No.2 358,772
 US. Cl. 166/136, 166/214  Int. Cl E2lb 23/00, E2lb 33/12  Field of Search 166/136-139, 166/213-217  References Cited 7 UNITED STATES PATENTS 2,673,614 3 1954 Miller...- 166/136 3,279,542 10/1966 Brown 166/139 3,292,717 12/1966 Hall et a1... 166/217 3,420,306 l/l969 Brown 166/215 3,698,477 10/1972 Radig 166/214 Primary Examiner.lames A. Leppink Attorney, Agent, or FirmDavid L. Moseley; Stewart F. Moore; William R. Sherman 57 ABSTRACT In accordance with an illustrative embodiment of the invention disclosed herein, an apparatus for releasably latching the lower end of a tubing string in a well casing having a landing nipple therein includes laterally flexible anchors carried by a body structure and held inwardly during running. When the anchors encounter the recesses in the nipple, they resile outwardly to stop downward movement, whereupon a clutch can be released to enable the body structure to be moved downwardly to releasably lock the anchors in set position; A seal on the body structure closes the tubing-tocasing annulus so that it can be used for a pressure path to a remote controlled safety valve installed inthe tubing above the latching apparatus.
11 Claims, 5 Drawing Figures LATCHING APPARATUS FOR INSTALLING SAFETY VALVES IN WELLS -,This invention relates generally to downhole safety valve installations, and more particularly to a new and improved latching assembly for anchoring the lower end of a production tubing having a remote controlled safety valve therein in a well casing.
Remote controlled safety valves are commonly used in producing wells as a means of providing downhole protection against disastrous surface fires and blowouts caused by-failure, leakage or loss of surface equipment such as valves and flow lines. This type of safety valve isusually spring loaded to be normally closed, but is held open by the pressure of fluid in a control line extending to the surface. An absence of control pressure in the line due to the sensing of actual or impending surface disaster enables the valve to automatically close and shut-in the well downhole.
The remote controlled type of safety valve, while being preferred by many well owners, requires the existence of a special landing sub in the production string. The sub normally has spaced apart seal surfaces with a lateral port therebetween that is coupled to the control line extending externally of the production string in order to feed pressure to the valve which is installed inside the sub. Where such equipment has not been previously installedas a part of the well casing program, it becomes quite expensive to make such an installation. Moreover, in the so-called tubingless completion wells, were a small diameter casing is cemented in the borehole and serves as the production string, it may not be possible to install the landing sub and control line necessary for convention remote control valve installation. However, it-has been typical practice to install in most wells at least a landing nipple that will ac-' cept a so-called velocity sensitive safety valve. This type of valve is spring loaded to be normally open and incorporates a flow restriction that creates a pressure drop, with the resultant force overcoming the spring at a predetermined excessive flow rate and causing the valve to close. Inasmuch as this type of valve is responsive to'excessive flow rate, a separate control pressure line that extends to the surface is not a requirement of the installation.
Moreover, the need for a separate control line itself has made the installation of remote controlled safety valve quite expensive compared to other type valves, since the line must be run with the tubing. This requires aconsiderable'amount of additional rig time and handling expense. 7 One object-of the present invention is to provide a new and improved apparatusthat enables a remote controlled safety valve to be readily installed in an existing well that does not have the previously positioned special equipment that is normally required for this type of installation.
Another object of the present invention is to provide a new and improved apparatus that enables the installation of a remote controlled safety valve in an existing well which eliminates the requirement for a separate control line extending to the top of the well.
These and other objects are attained in accordance with the concepts of the present invention through the provision of a latching apparatus for attaching the lower end of the production string to a previously installed, conventional, velocity valve landing nipple in 2 such a mannerthat the tubing-to-casing annulus can be used as a pressure path to control the operation of a remote controlled safety valve located in the tubing string thereabove. The apparatus, in a preferred form, comprises a body member or mandrel having its upper end adapted for connection tothe pipe string, and a friction drag assembly carried by its lower end portion. The drag assembly has friction elements in engagement with the well casing wall, and is movable between a lower position and an upper position with respect to the mandrel. The assembly is releasablycoupled to the mandrel in the lower position by a mechanism'that can be released in response to rotation of the tubing. An anchor sleeve is fixed to the upper end of the drag assembly and is provided with laterally flexible spring fingers having head portions that normally are held inwardly alongside a reduceddiameter section the mandrel as the apparatus is being run into the casing, however when the landing sub is reached the head portions are sized and arranged to shift outwardly into a locking recess in the sub. When this occurs the tubing can be. rotated to release the coupling to the drag assembly, and then lowered to cause the head portions to be engaged by a locking surface on the mandrel. Also, the head portions and mandrel have ratchet teeth that engage to lock the mandrel in its lower position where a seal as-' sembly on the upper end portion thereof engages a surrounding seal surface on the landing sub to prevent fluid leakage. Inasmuch as the total production flow must now pass through the mandrel and into the tubing, a remote controlled safety valve installed in the tubing thereabove can be-actuated because the tubing-tocasing annulus located above the seal assembly may be employed as a means to provide control .pressure to hold the valve open. Thus the apparatus of this invention enables this type of valve to-be installed in almost any existing well, and eliminates the need to have a separate control line that extends in the annulus-to the surface.
Thepresent invention has other objects and advantages that will become morereadily apparent in connection with the following detailed description, taken in conjunction with the appended drawings in which:
FIG. 1 is a schematic representation of a cased well with a production string of tubing anchored therein in accordance with the principles of the present invention.
FIGS. 2A and 2B are longitudinal sectional views of the latching apparatus with the parts in relative position for running into the well; and
FIGS. 3A and 3B are views similar to FIG. 2 except with parts in relative positions when anchored and sealed off with respect to a landing nipple installed in the casing. v 7
Referring initially to FIG. 1, a downhole safety valve installation is shown somewhat schematically as including a string of production tubing 10 located concentrically within a well casing 11. The well casing 11 has a landing nipple 12 disposed therein, and the latching assembly 13 in accordance with the concepts of the present invention is shown locked into the landing nipple. As will be described in greater detail herebelow, the latching assembly 13 includes a hollow mandrel 14 that carries anchors 15 to lock the assembly in place within the landing nipple 12, and seal packing 16 that prevents fluid leakage between the mandrel and the casing to confine the total flow of production fluids to the bore of the mandrel. A friction drag mechanism 17 together with a clutch l8 cooperates in enabling setting and release of the anchors in response to appropriate manipulation of the mandrel 14 by the tubing string 10.
The production string 10 can have a landing nipple positioned therein and adapted to receive a wireline settable and retrievable, remote controlled safety valve as will be familiar to those skilled in the art. As previously mentioned, this type of landing nipple has a port 21 located between upper and lower internal seal surfaces via which control pressure is communicated to the valve. For further detail of this type of landing nipple and safety valve, reference may be had to p. 3501 of the 1972-1973 edition of the Composite Catalog of Oilfield Equipment and Services. Alternatively, a typically constructed remote controlled subsurface safety valve can be joined in the tubing above the latching assembly 13, and would have a pressure port in direct communication with the annulus space between the tubing and the casing so that the valve can be maintained in the open position by fluid pressure applied to the annulus. In either case, moreover, the sub or the valve may be connected to the upper end of the man- ,drel 14 by a joint of tubing 22 or the like. In the event of surface disaster where the applied pressure is lost or dissipated, the valve is designed in a conventional manner to automatically close and shut-in the well.
Turning now to FIGS. 2A and 2B for structural details of the latching assembly 13, the mandrel 14 can be connected by threads 25 to the lower end of the section of tubing 22 and has an outwardly directed shoulder 26 above which is disposed the annular seal assembly 16. The seal assembly 16, which can take any suitable form, is shown as including chevron packing elements 27 and 28 together with appropriate spacer rings 29-31. The upper end of the seal assembly 16 may be retained by the lower end face 32 of the tubing section 22. When positioned within the landing nipple 12, the seal assembly 16 engages a surrounding seal surface so that the total flow of production fluids is constrained to pass through the central bore 33 of the mandrel 14. The lower end of the mandrel 14 is connected by threads 34 to a bottom sub 35 (FIG. 2B) through which the production fluids enter.
The friction drag assembly 17 is carried intermediate the ends of the mandrel l4 and includes a plurality of circumferentially spaced .bow springs 38 or the like that extend outwardly into frictional engagement with the inner wall surface of the casing 11 to prevent relative rotation. The ends of the bow springs 38 are retained by caps 39 and 40 that are located near the respective ends of an annular cage 41 and fixed with respect thereto by threads 42 or the like. The caps are, of course, arranged to provide for a certain amount of vertical movement of the ends of the bow springs to accomodate lateral flexure thereof. The cage 41 has a counterbore 43 that provides an upwardly facing stop surface 44 that is aligned for engagement by an outwardly directed shoulder 45 on the mandrel 14 to provide a stop limit to upward movement of the drag assembly with respect to the mandrel. However, as the device is being run into the well, the drag assembly 17 is held in a lower position with respect to the mandrel 14 by the clutch 18 that includes flexible fingers 46 depending from the lower cap 40 and having upwardly facing teeth 47 that are normally engaged with downwardly facing teeth 48 on the lower sub 35. The teeth 47 and 48 preferably are formed on aright hand helix so that rotation of the mandrel 14 to the right will unthread the sub 35 from the fingers 46 and enable downward movement. Of course the clutch 18 can be reengaged without rotation by simply moving the mandrel 14 upwardly because the teeth 48 can ratchet back into engagement with teeth 47 due to the capability of the fingers 46 to resile outwardly.
An anchor sleeve 50 is threaded at 51 to the upper end of the cage 41 and is longitudinally cut by a plurality of slots 52 all extending from the upper end thereof for less than its full length in order to provide a plurality of circumferentially spaced, flexible spring fingers 53. Each spring finger 53 has an enlarged head portion 54 at its upper end and an outwardly directed shoulder 55 intermediate its ends. The head portions 54 each have an upwardly and inwardly inclined upper surface 56 and a transverse lower surface 57, together with internal buttress-type threads 58 that face downwardly and are sized to mesh with external threads 59 on an enlarged section 60 of the mandrel 14 as will be more fully described herebelow. During running, the head portions 54 are located as shown in FIG. 2A adjacent to a reduced diameter portion 61 of the mandrel and are held in an inwardly flexed and inactive position by the shoulder 55 whose outer surfaces 62 are adapted to slide in contact with the inner wall of the casing 11. When the head portions 54 and shoulder 55 arrive at a landing nipple having complementary shaped internal recesses, however, they are permitted to move outwardly relative to the mandrel 14 to a position where the transverse surfaces 57 stop'downward movement. Moreover, when the clutch 18 is released as will be subsequently explained, the enlargeddiameter section 60 of the mandrel 14 can be positioned behind the head portions 54 in a manner such that a locking surface 64 will function to prevent inward movement. The external teeth 59 can be ratcheted into engagement with the internal teeth 58 to lock the mandrel 14 in a lower position within the landing nipple where'the seal assembly 16 engages a surrounding seal surface therein.
In operation, the parts are assembled as shown in the drawings and run into the casing l 1 with the threads 47 and 48 on the clutch sleeve'46 and the bottom sub 35, respectively, engaged to position the anchor assembly 15 and the drag assembly 17 in a lower position along the mandrel 14. The shoulder 55 engage in inner wall of the casing. 11 as shown in dotted lines in FIG. 2A, causing the fingers 53 to resile inwardly and thereby positioning the head portions 54 alongside the reduced diameter section 61 of the mandrel. When the latching assembly arrives at the seating nipple 12 as shown in FIG. 3A, which contains spaced apart internal recesses and 71 that are companion in shape and spacing to the outline of the head portions 54 and the shoulders ,55, the shoulders enter the lower recess 71 and enable surface 73. Then the mandrel 14 is rotated by the tubing 10 to the right, resulting in release of the clutch threads 47 and 48 since the cage 41 is held against rotation by the drag springs38. When the threads 47 and 48 are released, the mandrel 14 can be telescoped the lower end of the tubing is firmly anchored and sealed within the landing nipple 12. Moreover, the annular space 75 between the casing 11 and the tubing 10 provides a pressure path from the surface to the remote controlled safety .valve positioned within the nipple 20.
above the latching assembly 13.
To'release the tubing 10 so that the latching assembly.
13 and equipment thereabove can be withdrawn from the well, it is only'necessary to rotate the mandrel 14 to the right while holding a strain in the tubing. This causes the threads 58 and 59, which are preferably of left hand formation, to disengage and enables the locking surface 63 to be removed from behind the head portions 54 as the mandrel 14 shifts upwardly. At the limit of its upward relative movement, the clutch 18 will automatically engage as the sub teeth 48 ratchet back into engagement with the teeth 48 on the clutch sleeve 46. As the drag assembly 17 and the anchor sleeve 50 are forced upwardly, the spring fingers 53 are flexed inwardly to a disarmed position due to camming action of the inclined surfaces 56 and 74, and are held in such position by the shoulders 55 which disengage from the recess 71 and slide along the inner wall of the casing 11. The tubing can be removed from the'well, or for that matter the assembly '13 can be set and released as many times as desired to facilitate spacing procedures at the surface that are sometimes necessary when installing surface production facilities.
. It will now be recognized that a new and improved latching assembly has been provided that enables the installation of remotely controlled subsurface safety valve equipment in existing wells. Moreover, the tubing-to-casing annulus can be utilized asa pressure path for control pressure to actuate such valves, eliminating the need for running separate control pressure lines externally of the production tubing. Since certain changes or modifications may be made in the disclosed embodiment bythose skilled in the art without departing from the scope of the inventive concepts disclosed herein, it is the aim of the appended claims to cover all such changes or modifications falling within thetrue spirit and scope of the present invention.
1. Apparatus for use in anchoring in a well casing having a landing nipple provided therein, said'landing nipple having internal recess means, comprising: 'a body structure having an enlarged diameter section and a reduced diameter section; seal means on said body structure arranged to engage acompanion seal surface on said landing nipple for preventing fluid leakage; anchor means movable relatively along said body structure'and between an inner position adjacent said reduced diameter section and an outer position, said anchor means including surface means adapted to slide against the casing and hold said anchor means in said inner position, said surface means when encountering said recess means enabling outward movement of said anchoringmeans thereinto; clutch r'neansresporis'ive to manipulation of said body structure for selectively preventing or permitting longitudinal movement of said anchor means relatively along said body structure; and means provided on said enlarged diameter section of said body structure that can be positioned by longitudinal relative movement for locking said anchoring means in said outer position to anchor said production string in the well casing.
2. The apparatus of claim 1 wherein said anchor means includes a plurality of circumferentially spaced, flexible spring fingers each having an enlarged head portion shaped to cooperate with said recess means to prevent longitudinal movement when engaged therein.
3. The apparatus of claim 2 wherein said surface means is provided on the periphery of an outwardly directed shoulder on each of said spring fingers, said recess means being shaped and arranged to receive said shoulders and thereby enable outwardmovement.
4. The apparatus of claim 2 wherein said head portions and said enlarged diameter section of said body structure have releasable, coengageable means for preventing upward movement of said body tive to said head portions.
5. The apparatus of claim I wherein said clutch means comprises a coupling between said anchor means and said body structure'that can be released by movement of said body structure'with respect thereto; and further including means attached to said anchor means and frictionally engageable with the well casing for enabling movement of said body structure with respect to said anchor means. v
6. Apparatus for use in releasably securing a remote controlled safety valve attached in a production string within a well casing in such a manner that the annular space between the production string and the casing provides a means of communicating operating pressure to the safety valve, said casing having a landing nipple with vertically spaced recesses therein and an annular internal seal surface, comprising: a body structure having a through bore and carrying means engageable with said seal surface to confine a flow of production fluids to said through bore; anchor means on said body structure movable laterally with respect thereto between an inner inactive position and an outer active position in engagement .with one of said recesses; means engageable with the casing for holding said anchor means in said inactive position as said apparatus is being moved through the well bore, said holding means being received by the other of said recesses to enable outward movement of said anchoring means to said active position; means responsive to longitudinal movement of said body member relative to said anchor means for locking said anchor means in said active position; and selectively operable means responsive to manipulation of said body member by the production string for either preventing or permitting such longitudinal movement;
structure relacess, and when received therein to prevent longitudinal movement.
8. The apparatus of claim 7 wherein said locking means includes an enlarged diameter section of said body member having a locking surface that when located behind said head portions prevents inward movement thereof.
9. The apparatus of claim 8 further including coengageable means on said enlarged section and the inner surfaces of said head portions for preventing upward movement of said body member with respect thereto.
10. The apparatus of claim 7 wherein said holding means includes outwardly directed shoulder formations on each of said spring fingers, each shoulder formation providing an outer surface that slides in contact with the well casing wall to hold each head portion in said inactive position, said shoulder formations entering said other of said recesses to enable outward movement of said head portions to said active position.
1 l. The apparatus of claim 7 wherein said selectively operable means comprises a threaded coupling between said sleeve member and said body member for normally preventing relative movement, said coupling being releasable by relative rotation; and further including friction drag means connected to said sleeve member for enabling such relative rotation.