Step temperature well testing

Exact determination of thermal parameters is of high importance in a wide spectrum of both solid Earth investigations and subsurface geological and environmental studies. This article demonstrates a new revisited technique for the precise determination of formation thermal conductivity and contact thermal resistance in boreholes. We assume that the volumetric heat capacity of formations is a priori known, and the instantaneous heat flow rate and time data are available for the cylindrical probe located in borehole with a constant temperature. A dimensionless heat flow rate has been approximated by a new empirical equation, parameters of which were computed by use of the Newton method. An effectiveness of the proposed methodology is shown on modelled examples. A simulated case is given on example of metallic electrical heater placed into a vertical open (uncased) borehole.