A method to measure thermal conductivity and thermal diffusivity under pore and confining pressure

A measuring equipment was developed for the determination of thermal conduc tivity and thermal diffusivity of rocks under pore and confining pressure u p to 90 MPa and 300 MPa, respectively, A quadratic heater placed between tw o cubic samples generates a rectangular heat pulse of 5 s length. In one of the cubes the pulse response at a known distance from the heater is measur ed by a thermocouple. The sample holder is mounted on the upper plug of the used high pressure vessel. The whole sample arrangement is sealed against the pressure medium by an elastic polyurethene jacket. Pore fluid is introd uced into the pore space of the rock sample by a perforated back plate. A n umerical modelling of the pulse propagation is used to determine thermal co nductivity and thermal diffusivity from the measured pulse amplitude and ha lf value time. First results are given for a 16% porosity sandstone from Ob ernkirchen, Germany. (C) 2000 Elsevier Science Ltd. All rights reserved.