Patent ID: 8082105

Claim:
A computerized method for measuring in-situ stress in rock using a thermal crack, the method comprising: a borehole forming step of forming a borehole in the target rock for measuring in-situ stress; a first cooling step of cooling a wall of the borehole, applying tensile thermal stress to the borehole wall, forming and growing the crack in the borehole wall, and measuring a first cracking temperature of the borehole wall when the crack is formed and a cracking point at which the crack is formed; a heating step of heating the borehole wall cooled in the first cooling step and closing the crack; a second cooling step of cooling the borehole wall again, applying tensile terminal stress to the borehole wall, re-opening the crack closed in the heating step, and measuring a second cracking temperature of the borehole wall when the crack is re-opened; and a calculating step of calculating by a processor the in-situ stress of the rock using the first cracking temperature of the borehole wall and the cracking point, which are measured in the first cooling step, and using the second cracking temperature of the borehole wall, which is measured in the second cooling step.