Well Tool Latching System

Abstract

A system for securing well tools, such as gas lift valves, into a latching profile within a wellbore. A gas lift valve is provided having a latching arrangement wherein an apertured back-up ring is used to provide stability for the locking lugs throughout the process of latching and unlatching the gas lift valve.

1 . A latching arrangement for releasably securing a well tool within a bore in a wellbore, the latching arrangement comprising:
 an outer radial housing defining a window therein;   a locking lug that is at least partially disposed within the window and is moveable radially inwardly and outwardly with respect to the housing to removably lock the well tool within the bore; and   a backup ring disposed within the housing, the backup ring having a ring body having an aperture disposed therein, the aperture presenting first and second axially facing walls; and   the locking lug being at least partially disposed within the aperture of the backup ring and presenting first and second axial surfaces which adjoin the first and second walls of the backup ring, thereby precluding substantial rotation of the locking lug with respect to the backup ring.   
   
   
       2 . The latching arrangement of  claim 1  wherein the well tool is a gas lift valve. 
   
   
       3 . The latching arrangement of  claim 1  wherein the locking lug comprises a lug body and an ear portion which extends radially from the body, the ear portion preventing the locking lug from being moved entirely radially outwardly through the window. 
   
   
       4 . The latching arrangement of  claim 1  wherein:
 the backup ring has three apertures; and   there are three locking lugs.   
   
   
       5 . The latching arrangement of  claim 1  further comprising a mechanism for moving the locking lug radially outwardly with respect to the housing. 
   
   
       6 . The latching arrangement of  claim 5  wherein the mechanism for moving the locking lug comprises a generally cylindrical expander shaft disposed radially within the valve housing, locking lug and backup ring, the expander shaft presents:
 a first section having a first diameter;   a second section having a second diameter that is larger than the first diameter; and   wherein the expander shaft is axially moveable with respect to the locking lug to cause the locking lug to move radially outwardly as the lug is moved radially outwardly as the locking lug contacts the second section of the expander shaft.   
   
   
       7 . The latching arrangement of  claim 6  wherein the expander shaft is releasably secured to the outer radial housing by a frangible shear member. 
   
   
       8 . A gas lift valve for use in a side pocket mandrel within a wellbore, the side pocket mandrel having a bore, the gas lift valve comprising:
 a valve housing defining a window therein;   a locking lug that is moveable radially inwardly and outwardly through the window with respect to the valve housing for removably locking the gas lift valve into a latching profile in the bore;   a backup ring disposed within the valve housing, the backup ring comprising a ring body having an aperture disposed therein, the aperture presenting first and second axially facing walls; and   the locking lug being at least partially disposed within the aperture of the backup ring.   
   
   
       9 . The gas lift valve of  claim 8  further comprising a generally cylindrical expander shaft disposed radially within the valve housing, locking lug and backup ring, the expander shaft presents:
 a first section having a first diameter; and   a second section having a second diameter that is larger than the first diameter.   
   
   
       10 . The gas lift valve of  claim 8  wherein the locking lug comprises a lug body and an ear portion which extends radially from the body, the ear portion preventing the locking lug from being moved entirely radially outwardly through the window. 
   
   
       11 . The gas lift valve of  claim 9  wherein the expander shaft is releasably secured to the valve housing by a frangible shear member. 
   
   
       12 . The gas lift valve of  claim 9  wherein the expander shaft is axially moveable with respect to the locking lug to cause the locking lug to move radially outwardly as the lug is moved radially outwardly as the locking lug contacts the second section of the expander shaft. 
   
   
       13 . A method for releasably securing a well tool within a bore in a wellbore, the method comprising the steps of:
 disposing the well tool within the bore proximate a latching profile in the bore, the well tool having a latch housing which defines a window therein;   urging a locking lug radially outwardly through the window and into the latching profile; and   providing sliding contact between the locking lug and at least two axially facing walls of a backup ring lying radially within the latch housing to prevent substantial axial rotation of the locking lug with respect to the latch housing during radial outward movement of the to locking lug.   
   
   
       14 . The method of  claim 13  further comprising the steps of:
 moving the locking lug radially inwardly with respect to the latch housing; and   providing sliding contact between the locking lug and at least two axially facing walls of a backup ring lying radially within the latch housing to prevent substantial axial rotation of the locking lug with respect to the latch housing during radial outward movement of the locking lug.   
   
   
       15 . The method of  claim 14  wherein the locking lug is moved radially inwardly by compressive contact between the locking lug and the backup ring, which causes the locking lug to be moved inwardly by sliding contact against a shoulder within the bore.