Patent ID: 8967293
Filing Date: 2015-03-03
Classification: E21B

Abstract:
1. A method of thermal rock fragmentation in a borehole by an exothermic chemical reaction of at least two reactants in the presence of a water-based drilling fluid having a pressure of more than 1.5 bar, the method comprising the steps of: feeding the water-based drilling fluid to a downhole assembly in a borehole and ejecting said drilling fluid from the downhole assembly into the borehole; feeding the reactants for said exothermic reaction via feeding lines to said downhole assembly; forming a mixing zone by bringing the reactants together via outlets in the feeding lines and mixing said reactants in the mixing zone; and establishing the exothermic reaction of the reactants in a reaction zone, the reaction zone being located in a volume between the outlets of the feeding lines into said mixing zone and a rock surface in the borehole, wherein the reaction at least partly takes place in the presence of water-based drilling fluid, wherein the exothermic chemical reaction is in the presence of a water-based drilling fluid having a pressure corresponding to or exceeding the critical pressure of water.