32-15 Assessing Fault Reactivation Potential in the Californië Geothermal Site, Roer Valley Graben, Using 3D Geomechanical Modeling

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Fault reactivation in intraplate rift systems poses significant geomechanical and seismic risks, especially where subsurface operations alter stress and pore pressure conditions. This study investigates fault stability at the Californië geothermal site, located along the northeastern Roer Valley Graben—an actively deforming zone within the European Cenozoic Rift System.

High-resolution 3D structural modeling, based on seismic and well log data, delineates key fault systems including the Tegelen, Dülkener, Viersen, and Belfeld faults, along with the stratigraphy of the Carboniferous reservoir.

Geomechanical simulations at 2.0 km depth, under both normal and strike-slip regimes, quantify slip tendency (Ts), dilation tendency (Td), and slip stability using Mohr-Coulomb criteria. The Tegelen and Dülkener faults exhibit elevated Ts (~0.45) and Td (~0.68), indicating increased reactivation potential, particularly under transtensional conditions. The Belfeld fault, while less prone to slip, shows the highest average Td (~0.82), suggesting pathways for fluid migration.

Modeled slip stability improves at greater depths, yet critical segments may reactivate with pressure increases as low as 1–2 MPa. The study demonstrates the importance of integrating structural characterization with geomechanical modeling to inform safe geothermal development in tectonically sensitive rift environments.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10764

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