Patent ID: 7673566

Claim:
A method for use in a wellbore, comprising: lowering a tool having a heat insulating container and an explosive into the wellbore, wherein the heat insulating container has an opening and an inner space and a structure defining a vacuum layer, the tool further having: a reflective layer arranged on a surface of the heat insulating container to reflect heat for reducing heat radiation from the wellbore into the inner space, a signal-activated detonator provided into the inner space through the opening of the heat insulating container, a plug including a hollow that has a vacuum and the plug to fit into the opening to seal the inner space, and a filler mass inside the inner space to separate the detonator from an inner surface of the heat insulating container to protect the detonator from direct impact between the detonator and the heat insulating container, wherein the filler mass is formed of a heat insulating material; and activating the signal-activated detonator to cause detonation of the explosive.