Relation between Induced Microseismicity and Fracture Network in the Basel Geothermal Site

Permeability creation during hydraulic stimulation of Enhanced Geothermal System (EGS) reservoirs is accompanied in part with induced microseismicity. A satisfactory reservoir characterization is required to mitigate the seismic risk and evaluate different development scenarios with valid hazard assessment. Creating a representative three dimensional structural model in the early stages of reservoir creation is difficult because of insufficient information on the geometry of fracture network from deep boreholes data. In this analysis, we characterized the spatial patterns of induced microseismicity in the Basel geothermal system and analyzed the rupture radius distribution. We generated and analysed synthetic data to help us with the interpretation of the correlation function of spatial patterns. Assuming a constant stress drop on every seismic event, the rupture radius distribution showed a power-law distribution. The correlation function of induced patterns showed a slope of 2 indicating the existence of a fractured zone. In addition, the existence of repeating events explains the observed drop on the local slope of the corresponding correlation function.

, 2018