Thermal Conductivity Systems for Measurements on Rocks under Applied Stress
A simple, unguarded-plate apparatus has been shown effective for medium-precision measurements of thermal conductivity with applied uniaxial pressures. Measurements on Minnekahta limestone samples have been made at 20°C under pressures of 1.2 to 18.3 MPa. Both the low pressure values and the pressure dependence of the thermal conductivity are dependent upon the sample. An unjointed sample had a conductivity of 2.57 Wm−1K−1 at 1.2 MPa which increased to 2.73 Wm−1K−1 at 18.3 MPa, while a jointed sample had an initial conductivity of 3.19 Wm−1K−1 which decreased to 3.12 Wm−1K−1 upon loading to 18.3 MPa and then further decreased to 2.78 Wm−1K−1 upon unloading to 1.2 MPa. A nylon sample used for calibration initially showed an increase in thermal conductivity of 7% as the pressure was increased from 1.2 to 18.3 MPa, but this pressure dependence disappeared after repeated pressure cycling.
KeywordsThermal Conductivity Pressure Dependence Salt Dome Limestone Sample Sample Assembly
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