Hydro-mechanical reservoir models are used to obtain quantitative insights into the spatial distribution of stress, strain and pore pressure. Recent studies have shown that different approaches to incorporate faults into such reservoir simulations have a profound impact on the modeling results. Since faults are a key feature in the subsurface affecting both the hydraulic and mechanical behavior of a reservoir, their proper implementation in the numerical model is crucial. Fault representation

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... s to accurately model the effect faults have on (1) fluid flow and (2) the local stress field. However, a fault is not just a discrete geological feature but rather a fault zone with a complex geometry and various rock units with distinct material properties. This small-scale heterogeneity can hardly be represented in reservoir scale finite element models considering the typical grid size used in these simulations. Thus, fault representation in reservoir-scale hydro-mechanical simulations has to be based on simplifications and upscaling techniques. To improve decision making and help in choosing the right fault representation, knowledge about the different effects each simplification and each approach used to incorporate faults has on the modeling results is necessary. This thesis focuses on different approaches of fault representation with a single upscaled set of material properties in reservoir-scale hydro-mechanical finite element models. The main objectives are (1) Implementing the fault geometry with respect to the finite element grid properly (2) Addressing the scale differences between the internal heterogeneity of the fault zone (centimeters to meters) and the typical size of the calculation cells of the numerical grid (meters to tens of meters) accurately (3) Assigning fault material properties to the numerical models, which stem – if available at all – from rock mechanical testing on core samples with a diameter of a few centimeters and therefore require upscaling and merging techniques In order to meet these ch [...]