ABSTRACT
The value of HFD determines the amount of heat per unit of area and per unit of time which is transmitted by heat conduction from the Earth’s interior . For isotropic and homogeneous formations, where coeffi cient of thermal conductivity (λ) is a constant, the value of heat-fl ow density, HFD (q means vector), can be calculated from the Fourier equation :
.Tgradλ−=q (17-2) The minus sign shows that heat fl ows from points with high temperatures to
points with lower temperatures. Thus to calculate the HFD we need to estimate the value of the static (undisturbed) geothermal gradient (Г) and to measure the thermal conductivity of the formation. Two methods of combining thermal conductivity and temperature gradient data are used: interval method and the Bullard method (Powell et al. 1988). It is assumed that the effect of climatic changes , relief, underground water movement, subsurface conductivity variations on the temperature gradient (G) have been estimated and the corrected value of G is close to the value of Г. In the interval method, for each depth interval a temperature gradient is combined with the representative value of formation thermal conductivity .
