Effects of a Fluid Annulus on the Performance of Thermal Transducers in a Bore Hole: Sensitivity Analyses

摘要

The subject down-hole thermal transducer development program relates to two different transducer types. One is used to measure the geothermal heat flux under steady state conditions and the other one is used to determine the thermal conductivity and thermal capacity of the earth. In both instances, the measurements are made in place in a bore hole and no core sampling is required. When inserting these transducers into the bore hole, it is clear that a fluid annulus exists between the transducer and the hole. This report describes the effects of the fluid annulus on the transducer performance. On the basis of the analytical work performed, as well as other considerations, the limitations on the annulus thicknesses for these transducers when in a hole are discussed. In addition, the signal outputs for the two measurement methods are considered.