Trigger for downhole tool, method and system

Abstract

A trigger including a carrier, a shuttle movably disposed on the carrier, an energy member disposed between the carrier and the shuttle, a degrade-on-demand trip member disposed to maintain potential energy in the energy member until activated. A method for operating a downhole tool including sending a signal to the trip member of the trigger, degrading the trip member, converting potential energy stored in the energy member from potential energy to kinetic energy, and actuating the downhole tool with the shuttle. A wellbore system including a borehole in a subsurface formation, a string in the borehole, a trigger disposed within or as a part of the string.

1 . A trigger comprising:
 a carrier configured to be exposed to downhole fluids when in use;   a shuttle movably disposed on the carrier;   an energy member disposed between the carrier and the shuttle;   a degrade-on-demand trip member, configured to be exposed to downhole fluids when in use disposed to maintain potential energy in the energy member until activated.   
     
     
         2 . The trigger as claimed in  claim 1  wherein the trip member is impervious to a downhole environment. 
     
     
         3 . The trigger as claimed in  claim 1  wherein the trip member is in compression by the energy member. 
     
     
         4 . The trigger as claimed in  claim 1  wherein the trip member is in tension by the energy member. 
     
     
         5 . The trigger as claimed in  claim 1  wherein the energy member is a compression member. 
     
     
         6 . The trigger as claimed in  claim 1  wherein the energy member is a tension member. 
     
     
         7 . The trigger as claimed in  claim 1  wherein the carrier comprises a rod upon which the shuttle is sliding engaged. 
     
     
         8 . The trigger as claimed in  claim 1  wherein the carrier comprises two rods upon which the shuttle is slidingly engaged. 
     
     
         9 . The trigger as claimed in  claim 8  wherein the energy member is two members, one disposed adjacent each of the two rods. 
     
     
         10 . A downhole tool comprising:
 a tool;   a trigger as claimed in  claim 1  operably connected to the tool.   
     
     
         11 . A method for operating a downhole tool comprising:
 exposing the trip member of the trigger as claimed in  claim 1  to downhole fluids;   sending a signal to the trip member;   degrading the trip member;   converting potential energy stored in the energy member from potential energy to kinetic energy; and   actuating the downhole tool with the shuttle.   
     
     
         12 . A wellbore system comprising:
 a borehole in a subsurface formation;   a string in the borehole;   a trigger as claimed in  claim 1  disposed within or as a part of the string.