In-situ-Measurements for the Determination of geothermal Underground Parameters

The efficiency of a borehole heat exchanger system depends on the geothermal properties of the soil. To design the geothermal system in a cost effective and technically competent way, it is necessary to know the thermo-physical parameters of the ground at the project location. The increasing significance of quality management and the examination of already existing geothermal installations continue to gain in importance. To satisfy these requirements a temperature-depth-measuring system for borhole heat exchangers (EWS-Logger) was developed. The Logger also called Erzhauser-Sonde is one part of a rapid and low cost in-situ-method to determine geothermal underground parameters. The analysis of data collected from a research borehole using the EWS-Logger in a water filled borehole heat exchanger, enabled several geothermal parameters to be determined. A comparison of parameters obtained from the EWS-Logs with results from geothermal response tests and laboratory tests show an extensive correlation. With adequate data collection the EWS-Logger can be deployed as a long term monitoring system for a borehole heat exchanger.