Characterization of Geologic and Geophysical Environments Using GRT Data. Scope of Enhanced Data Interpretation

Abstract

A (enhanced) Geothermal Response Test is common to determine geophysical parameters (i.e. thermal conductivity and volumetric heat capacity) of the subsoil. Data that are collected at such measurements can be utilized to get additional information of the subsoil and the measurement itself. Using different heat source approaches enable to evaluate measurements at different heat exchanger designs (e.g. u-tube heat exchangers, piles, baskets, etc.). It is important to choose the right approach to avoid misinterpretation and wrong values. Analog to hydro geologic methods time to distance calculations show the depth of thermal investigation into the surrounding rock. Determination of grout and rock properties is feasible. Using these methods on high resolution fiber optical measurements (enhanced GRT) allow determination of local rock properties and localizing grouting failure as well. Further the Darcy velocity of the groundwater affecting the heat exchanger while measurement can be calculated. Temperature profiles over depth pre and post (e)GRT can be used to indentify vertical groundwater flow through incomplete backfilling at a BHE. Serial profiles over depth and time post GRT show the quality of contact from the BHE to the surrounding rock. Determination of groundwater influence and grouting failure is also feasible. Much different information can be obtained from one data set without additional measurement. The more information is available the merrier and precise a geothermal array can designed.