Latch tool

Abstract

A latch tool for a wireline toolstring includes an anchor assembly that is attached to a support structure. A core assembly is configured for axial movement relative to the anchor assembly. The anchor assembly and the core assembly provide a spring chamber having a length that changes with axial movement of the core assembly. A spring opposes axial movement of the core assembly. A latch assembly includes at least one latching element that captures a coupling component. The spring provides a bias force that opposes axial movement of the core assembly in a latching direction, but permits axial movement of the core assembly in the latching direction when an axial force applied to the core assembly exceeds the bias force.

What is claimed is: 
     
         1 . A latch tool for capturing a wireline toolstring having a coupling component attached to a wire, the latch tool comprising:
 an anchor assembly having a longitudinal axis and configured to be attached to a support structure;   a core assembly connected to the anchor assembly and configured for axial movement relative to the anchor assembly, the anchor assembly and the core assembly providing a spring chamber having an axial length that changes with axial movement of the core assembly;   a spring located in the spring chamber and configured to be deformed by axial movement of the core assembly relative to the anchor assembly; and   a latch assembly connected to the anchor assembly, the latch assembly including at least one latching element configured to capture a coupling component when the coupling component moves in an axial latching direction relative to the latch assembly from an unlatched position to a latched position, and to prevent subsequent disengagement of the coupling component from the latch tool;   wherein the core assembly is configured to engage the coupling component during movement of the coupling component from the unlatched position to the latched position,   and wherein the spring provides a bias force that acts on the core assembly and opposes axial movement of the core assembly in the latching direction, but permits axial movement of the core assembly in the latching direction when an axial force applied to the core assembly by the coupling component exceeds said bias force.   
     
     
         2 . The latch tool according to  claim 1 , wherein the spring is configured to provide a bias force that opposes engagement of a coupling component with the latch assembly, but permits latching engagement of a coupling component with the latch assembly when an axial force applied to the core assembly by the coupling component exceeds a latching bias force provided by the spring. 
     
     
         3 . The latch tool according to  claim 1 , wherein the length and/or the spring constant of the spring is adjustable. 
     
     
         4 . The latch tool according to  claim 3 , wherein the spring comprises a plurality of disc springs. 
     
     
         5 . The latch tool according to  claim 1 , wherein the latch assembly is configured for axial movement relative to the anchor assembly. 
     
     
         6 . The latch tool according to  claim 5 , wherein the latch assembly is configured for axial movement relative to the anchor assembly over a first range of movement R1, and the core assembly is configured for axial movement relative to the anchor assembly over a second range of movement R2, where R1<R2. 
     
     
         7 . The latch tool according to  claim 1 , preceding claims, wherein the latch assembly comprises a plurality of latch elements that are resiliently biased towards a latching configuration. 
     
     
         8 . The latch tool according to  claim 7 , wherein the plurality of latch elements comprise a plurality of resiliently deformable fingers, each finger carrying a latching formation at a free end of the finger. 
     
     
         9 . The latch tool according to  claim 7 , wherein each latch element comprises a cam surface that is engageable by the coupling component when in an unlatched configuration, and a latching surface that is engageable by the coupling component when in a latched configuration. 
     
     
         10 . The latch tool according to  claim 8 , wherein each latch element comprises a cam surface that is engageable by the coupling component when in an unlatched configuration, and a latching surface that is engageable by the coupling component when in a latched configuration. 
     
     
         11 . A latch tool for capturing a wireline toolstring having a coupling component attached to a wire, the latch tool comprising:
 an anchor assembly having a longitudinal axis and configured to be attached to a support structure;   a core assembly connected to the anchor assembly and configured for axial movement relative to the anchor assembly, the anchor assembly and the core assembly providing a spring chamber having an axial length that changes with axial movement of the core assembly;   a spring located in the spring chamber and configured to be deformed by axial movement of the core assembly relative to the anchor assembly; and   a latch assembly connected to the anchor assembly, the latch assembly including at least one latching element configured to capture a coupling component when the coupling component moves in a latching direction towards the latch assembly from an unlatched position to a latched position, and to prevent subsequent disengagement of the coupling component from the latch tool;   wherein the core assembly is configured to engage the coupling component during movement of the coupling component from the unlatched position to the latched position,   and wherein the spring provides a bias force that acts on the core assembly and opposes axial movement of the core assembly in the latching direction, but permits axial movement of the core assembly in the latching direction when an axial force applied to the core assembly by the coupling component exceeds said bias force.   
     
     
         12 . A latch tool for capturing a wireline toolstring having a coupling component attached to a wire, the latch tool comprising:
 an anchor assembly having a longitudinal axis and configured to be attached to a support structure;   a core assembly connected to the anchor assembly and configured for axial movement relative to the anchor assembly, the anchor assembly and the core assembly providing a spring chamber having an axial length that changes with axial movement of the core assembly;   a spring located in the spring chamber and configured to be deformed by axial movement of the core assembly relative to the anchor assembly; and   a latch assembly connected to the anchor assembly, the latch assembly including at least one latching element configured to capture a coupling component when the coupling component moves in a latching direction towards the latch assembly from an unlatched position to a latched position, and to prevent subsequent disengagement of the coupling component from the latch tool;   wherein the core assembly is configured to engage the coupling component during movement of the coupling component from the unlatched position to the latched position;   wherein the spring provides a bias force that acts on the core assembly and opposes axial movement of the core assembly in the latching direction, but permits axial movement of the core assembly in the latching direction when an axial force applied to the core assembly by the coupling component exceeds said bias force;   and wherein the latch assembly is configured for axial movement relative to the anchor assembly.