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

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... rs 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-