Temperature Dependence of the Thermal Conductivity of Core Samples from a Test Well at Yakedake Hot Dry Rock Geothermal Area and in situ Conduction Heat Flow

Abstract

Hot Dry Rock technology requires detailed information on the dependences of the thermal properties of rocks on temperature, pressure, moisture and mineralogy up to the depth of the order of five kilometers. Thermal conductivities were measured by the needle probe method at atmospheric pressure. Temperature dependences of the thermal conductivity of 40 dried core samples from HSV-1 Well having 1000 m depth at the field test site for HDR technology in the Yakedake geothermal area, Gifu prefecture were presented in the temperature range from 30 to 500°C. The thermal conductivity of the dry core samples, λea, exhibited a θ+b, -aθ+b and cd^θ< dependences on temperature, θ, macroscopically (where, a, b, c and d>0 and are constants). In situ conduction heat flows at the depths from 40 to 1000m were estimated by the above thermal conductivity data and the temperature logging data. The estimated results offered useful informations on the fracture zones of the HSV-1 Well.