Abstract: A method and a device to thermally fragment rock for excavation of vertical and directional boreholes in rock formations, preferentially hard rock, using highly exothermic reactions. Exothermic reactions are initiated directly in the pressurized, aqueous environment of a water-based drilling fluid preferably above the critical pressure of water (221 bar). After reaction onset temperatures within the reaction zone exceed the critical temperature for water (374° C.) providing supercritical conditions, which favor the stabilization of the reaction, e.g. a supercritical hydrothermal flame. Since reactions can be run directly in a water-based drilling fluid, the method proposed here allows high density drilling action as in conventional rotary drilling. A part from the hot reaction zone of the proposed reaction can be brought directly to the rock surface in case of hard polycrystalline rock, where high temperatures are required.

Abstract: A method and a device to thermally fragment rock for excavation of vertical and directional boreholes in rock formations, preferentially hard rock, using highly exothermic reactions. Exothermic reactions are initiated directly in the pressurized, aqueous environment of a water-based drilling fluid preferably above the critical pressure of water (221 bar). After reaction onset temperatures within the reaction zone exceed the critical temperature for water (374° C.) providing supercritical conditions, which favor the stabilization of the reaction, e.g. a supercritical hydrothermal flame. Since reactions can be run directly in a water-based drilling fluid, the method proposed here allows high density drilling action as in conventional rotary drilling. A part from the hot reaction zone of the proposed reaction can be brought directly to the rock surface in case of hard polycrystalline rock, where high temperatures are required.