US Patent 7832474 Thermal actuator

An embodiment of a system for disconnecting a first element from a second element at a desired position in a wellbore includes a disconnect tool containing an expandable material, the disconnect tool being actuatable from a locked position, wherein the first and the second elements are interconnected, to an unlocked position, wherein the first and the second element are disconnected, upon a determined expansion of the expandable material in response to a temperature at the desired position.