In situ stress variations near faults considering fault zone rock rheology - implications for reservoir stimulation and associated seismicity

Lay summary

The project seeks a better understanding of the in situ stress spatial variations near fault zone from the far-field, to the damage zone and to the fault core. The research is conducted in the context of improving hydraulic stimulation and mitigating seismicity in reservoirs for geothermal systems (and/or hydrocarbons, waste disposal), as faults act as both fluid conduits and earthquake sources. This project is closely associated with the field experiments of the Swiss Competence Center for Energy Research – Supply of Electricity (SCCER-SoE) in the planned Bedretto Underground Laboratory, Swiss Central Alps. which serves as a key step to address the Swiss Energy Strategy by 2050 for 7% deep geothermal energy (from hot dry rocks). Primarily, the project strives to tackle the following challenges (among others):

An integrated geomechanics study via the combined field, laboratory and theoretical approaches will be established to resolve these challenges. Specifically, the study will begin with a field component to characterize the in situ stress state (and its variations) near the faults intersecting the Bedretto Underground Laboratory (BUL). The measured in situ stress variations and the characterized fault structures will be correlated to identify a plausible causal relationshipThis is followed by attempts to extrapolate the likely stress variations around the faults, based on the laboratory-derived relationship. The predicted stress variations will be compared with the in situ measurements.