Lug latching system for coupling a lubricator to a wellhead

Abstract

A latching system includes a stinger which is attached to a wellhead and a coupler assembly attached to surface equipment such as a lubricator, the coupler assembly having a latching mechanism for securely engaging the stinger, the latching mechanism moveable between a locked position, an unlocked position, and at least one transition position; and an indexing mechanism for indexing the latching mechanism from an unlocked position to a locked position, and from a locked position to an unlocked position, wherein the indexing mechanism is configured to translate vertical movement of the coupler assembly to index the latching mechanism.

1 . A latching system comprising:
 (a) a stinger;   (b) a coupler assembly having:
 a. a latching mechanism for securely engaging the stinger, the latching mechanism moveable between a locked position, an unlocked position, and at least one transition position; and 
 b. an indexing mechanism for indexing the latching mechanism from an unlocked position to a locked position, and from a locked position to an unlocked position, wherein the indexing mechanism is configured to translate vertical movement of the coupler assembly to index the latching mechanism. 
   
     
     
         2 . The latching system of  claim 1 , wherein the stinger is configured to attach to an upper end of a wellhead and the coupler assembly is configured to attach to a lower end of a surface equipment. 
     
     
         3 . The latching system of  claim 1 , wherein the indexing mechanism comprises a cam ring defining a cam slot and a cam follower sleeve having at least one cam follower, wherein the cam follower is positioned within the cam slot and follows an indexing pattern when the cam ring is moved axially relative to the cam follower sleeve. 
     
     
         4 . The latching system of  claim 3  wherein the cam ring is disposed within the cam follower sleeve. 
     
     
         5 . The latching system of  claim 1  wherein the latching mechanism comprises a lug housing and at least one moveable lug which extends radially inward to engage the stinger in response to movement of the indexing mechanism. 
     
     
         6 . The latching system of  claim 5  wherein the at least one lug comprise an element which engages a shoulder, a ridge, a thread, or a detent formed on or by the stinger. 
     
     
         7 . The latching system of  claim 4 , wherein the cam ring defines an internal profile having a internal diameter which varies along the length of the cam ring, and which bears on the latching mechanism, such that axial movement of the cam ring relative to the latching mechanism causes the lugs to extend or permits the lugs to retract. 
     
     
         8 . The latching system of  claim 1 , further comprising a centering cone positioned either on the stinger or the coupling assembly to aid in vertical alignment of the latching system. 
     
     
         9 . The latching system of  claim 6 , wherein the at least one lug comprises a planar surface which engages a locking shoulder formed on the stinger. 
     
     
         10 . The latching system of  claim 6 , wherein the at least one lug comprises an ovoid or cylindrical surface which engages a matching detent formed on the stinger. 
     
     
         11 . The latching system of  claim 6  comprising a plurality of lugs arrayed in at least one horizontal row. 
     
     
         12 . The latching system of  claim 11  comprising a plurality of lugs arrayed in two or more horizontal rows. 
     
     
         13 . The latching system of  claim 3  comprising a cam spring for biasing the cam ring downwards. 
     
     
         14 . The latching system of  claim 1  further comprising a visual indicator indicative of the system being in an unlocked position and/or a locked position. 
     
     
         15 . The latching system of  claim 14 , wherein the visual indicator is a colored stripe which is indicative of the axial position of the indexing mechanism. 
     
     
         16 . A latching coupler assembly for connecting to a stinger having a lock feature, comprising:
 (a) a lug housing having at least one latching component and configured to receive the stinger, the at least one latching component moveable between a locked state engaging the stinger lock feature and an unlocked state;   (b) a cylindrical cam ring disposed around the lug housing and moveable both axially and rotationally around the lug housing, the cam ring defining an exterior cam profile groove having at least one lock position, at least one unlock position, and an intermediate transition position, the cam ring further having an internal profile bearing on the at least one lug assembly to move each lug inward to its locked position;   (c) a cam follower sleeve affixed to the lug housing and disposed around the cam ring, the cam follower sleeve having at least one cam follower which engages the cam profile groove;   (d) wherein axial movement of the cam ring relative to the cam follower sleeve causes the cam follower to move within the cam profile groove between the lock position, the unlock position and the transition position, thereby moving the at least one latching component to its locked state or its unlocked state.   
     
     
         17 . The latching coupler assembly of  claim 16 , wherein the lock feature is a shoulder and the latching component comprises a lug moveable radially inwards to engage the shoulder. 
     
     
         18 . A method of latching and unlatching a surface equipment to a wellhead, comprising the steps of:
 (a) lowering a coupler assembly attached to the surface equipment onto a stinger attached to the wellhead;   (b) indexing the coupler assembly from an installation configuration to a first transition position by setting the coupler assembly down on the stinger;   (c) indexing the coupler to a locked configuration by pulling up on the coupler assembly, which actuates a latching assembly to extend at least one lug radially inwards to securely engage the coupler assembly to the stinger; and   (d) indexing the coupler assembly to a second transition position by setting the coupler assembly down and unlocking by pulling up the coupler assembly, which actuates the latching assembly to release the stinger by retracting the at least one lug radially outwards.