Patent ID: 7726406
Filing Date: 2010-06-01
Classification: E21B

Abstract:
1. A trigger device for a downhole tool, the trigger device capable of selectively actuating the downhole tool, the trigger device comprising: a housing comprising a housing passage disposed in a wall of the housing; a mandrel disposed within the housing; an actuating member operatively connected to the housing wherein the movement of the actuating member causes a downhole tool to perform a specified function; and a restraining member operatively associated with the actuating member, the restraining member restraining movement of the actuating member with respect to the housing, the restraining member comprising a dissolvable material such that dissolution of the dissolvable material by a dissolving fluid causes the restraining member to no longer restrain movement of the actuating member such that the actuating member is capable of moving to actuate the downhole tool, wherein the actuating member comprises a piston in sliding engagement with the mandrel and an inner wall surface of the housing, the piston comprising a piston inner diameter portion and a piston port, the piston port being in fluid communication with the piston inner diameter portion and the housing passage, and wherein the dissolvable material comprises a sleeve, the sleeve being disposed within the piston inner diameter portion, and the sleeve comprising a sleeve inner diameter portion that is in contact with the mandrel and a lower end that engages an upward facing shoulder of the mandrel.