Petrothermal and aquifer-based EGS in the Northern-German Sedimentary Basin, investigated by conservative tracers during single-well injection-flowback and production tests

Abstract The use of artificial tracers in single-well tests in conjunction with EGS-related fracturing or stimulation of sedimentary and crystalline formations in the N-German Basin is evaluated. Conservative-tracer signal analysis is suggested as a tool to quantify individual fracture contributions to multiple-fracture discharge, and illustrated with preliminary data from the Gros Schonebeck site. The proposed approach helps to avoid investing in unnecessary wellbore completion-integrated devices used for inflow profiling, especially when the productivity of the target formation is uncertain. Conservative-tracer signal analysis is further applied to estimate the thermal-lifetime contributions from the petrothermal and the aquifer components of a hybrid EGS developed in sedimentary formations at the Horstberg site. Long-term observation of tracer signals is recommended for both sites.