Abstract:

The results of the stimulations of the deep wells at Soultz-sous-Forêt show that the well presenting the best initial injectivity is not necessarily the most efficient after stimulation. The combination of shearing triggering mechanisms related to the relative orientation of faults with respect to stresses, with the "structural patterns" of the different wells related to geological hazard can largely explain the different responses to hydraulic stimulation from a well to another. The "structural pattern" includes, in this study, not only directional characteristics but different characteristics of the elements constituting the network of faults (aperture, roughness, mechanical properties). The models presented in the paper show the possibility of an "indirect stimulation" of some faults a priori less favorably oriented from the direct stimulation of faults more favorably oriented. To go further in the exploitation of the models, the link of the hydro-mechanical behavior of the fault network with the triggering of major microseismic events is initiated and highlights the need to introduce a more sophisticated fault behavior law such as Continuously Yielding Joint Model.

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