Fault growth and reactivation in the West Netherlands Basin: Implications for subsurface renewable energy projects

Reconstructing the spatiotemporal evolution of fault systems in rift basins is essential for characterizing reservoirs used in geothermal exploration and CO₂ or hydrogen storage projects. This study aims to elucidate the growth and reactivation of inverted normal faults in the West Netherlands Basin and their implications for subsurface renewable energy projects. With a complex tectonic history, the area experienced multiple rifting phases and basin inversion. Fault displacement-distance diagrams were produced by using an updated semi-automated workflow for nine major basin-scale faults, providing new insights into the lateral and vertical growth of faults in inverted rift basins.

This study demonstrates that the faults in the West Netherlands Basin developed their lateral lengths during the early stages of Triassic rifting. Subsequent Jurassic extensional phases caused reactivation, leading to a consequent increase of vertical displacement and creating accommodation space for the deposition of the study area’s main reservoir rock. Variations in the reactivation behaviour along the different fault segments were promoted by stress field rotations, which significantly influenced the distribution and extent of sediment deposition. This resulted in a complex reservoir architecture that is characterized by spatial heterogeneities in porosity and permeability.

We identified contractional features, such as pop-up structures and fault-propagation folds, formed by positive fault reactivation during Late Cretaceous basin inversion. The strength of inversion was influenced by the geometry and orientation of pre-existing faults and the thickness of the underlying sedimentary cover. Inversion-related structures further complicate the basin’s architecture, by compartmentalizing the reservoir rock and influencing sediment distribution patterns.

Our findings show an example of how fault dynamics can affect the geothermal reservoir quality and storage capacity of subsurface exploration targets. This study provides valuable insights for optimizing exploration strategies and storage site selection by integrating fault growth and reactivation analysis. This helps to further reduce geothermal exploration risks and enhances storage efficiency in rift basin settings.