Abstract: A welding tool for welding a blanking plate within a wellbore casing downhole thereby sealing the wellbore is described. The tool comprises a tubular body of a diameter sufficiently narrow to fit in a wellbore casing, the tubular body having a downhole end and a surface end; and a welding head assembly connected to the downhole end of the tubular body. The welding head assembly comprises a connector device for retaining a blanking plate to be welded within the wellbore casing, and a welding powder container which comprises a chamber for holding the exothermic welding powder, the chamber having at least a portion extending adjacent the blanking plate to be retained and proximate the wellbore casing to which the blanking plate is to be welded when the tool is positioned downhole in the wellbore casing; and an igniter wire opening for accommodating an igniter wire extending into the chamber.

Abstract: A welding tool for welding a blanking plate within a wellbore casing downhole thereby sealing the wellbore is described. The tool comprises a tubular body of a diameter sufficiently narrow to fit in a wellbore casing, the tubular body having a downhole end and a surface end; and a welding head assembly connected to the downhole end of the tubular body. The welding head assembly comprises a connector device for retaining a blanking plate to be welded within the wellbore casing, and a welding powder container which comprises a chamber for holding the exothermic welding powder, the chamber having at least a portion extending adjacent the blanking plate to be retained and proximate the wellbore casing to which the blanking plate is to be welded when the tool is positioned downhole in the wellbore casing; and an igniter wire opening for accommodating an igniter wire extending into the chamber.