EGS in Sedimentary Basins: Sensitivity of Early-flowback Tracer Signals to Induced Fracture Parameters

Short-term flowback signals from injection-flowback tracer test face a certain degree of ambiguity in fracture parameter inversion from the measured signal of a single tracer. This ambiguity can be overcome by combining different sources of information (lithostratigraphy, and hydraulic monitoring) and concomitantly using several tracers with different transport behavior. To improve the early-time characterization of induced fractures, of either gel-proppant or waterfrac, we recommend using tracers of contrasting sorptivity to rock surfaces, and to proppant coatings where applicable. We illustrate the application of such tracer combinations using hydro- and lithostratigraphy data from the Geothermal In-situ Laboratory at Groß Schönebeck, Germany.