Development of Downhole Geothermal Heat Flux and Thermal Conductivity Transducers

Abstract

Two new downhole geothermal transducers were developed for the Department of Energy for the purpose of measuring the geothermal heat flux and thermal conductivity in exploration holes without the necessity of taking core samples. One transducer system was based on the principle of quasi steady state two dimensional heat conduction; the transducers consisted of cylindrical rods having thermal conductivities different from the surrounding earth. A second cylindrical transducer system based on a transient conduction generated a step function heat flux that was transferred into the earth. Both systems required that the annular space between the transducer and the hole wall be filled with water or a drilling fluid. This paper describes the new measurement techniques, the field tests and the results.