| Title | Flow Partitioning and Viscosity-Driven Dynamics in a Geothermal Multilayer Aquifer of the North German Basin |
|---|---|
| Authors | Kimberley Niehage |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | multilayer-aquifer; temperature-dependent viscosity; hydrothermal doublet; Flow partitioning |
| Abstract | Geothermal reservoir modeling often focuses on fractured or single-layer systems, even though multilayer porous aquifers offer an additional opportunity for geothermal energy extraction. This study examines how specific modeling assumptions influence the flow field and thermal evolution in stratified geothermal systems. It focuses on a representative multilayer aquifer of the Bueckeberg Formation in the North German Basin. The targeted interval contains stacked sandstone units separated by claystone between depths of 1200 and 1400 m with reservoir temperatures around 70°C and injection rates of several tens of liters per second. A 3D numerical model is developed in the open-source software OpenGeoSys to evaluate how temperature-dependent viscosity affects flow distribution, pressure development and heat transport in this multilayer setting. Three numerical injection approaches are compared, including line- and surface-based source terms with imposed flow rates into the sandstone layers. Further, a pipe-based injection is tested, allowing the injected water to divide freely between the layers governed by the geological and hydraulic properties of the multilayer aquifer. Preliminary results show that temperature-dependent viscosity noticeably alters the flow field and affects the evolution of production temperature. These tendencies confirm the relevance of viscosity formulation when analyzing thermal behavior in geothermal systems. The ongoing comparison of injection approaches extends these findings by including the influence of inflow patterns on the flow field near the wells, where flow paths in multilayer aquifers are inherently more complex. This highlights the importance of choosing appropriate inflow conditions for modeling the thermo-hydraulic response of stratified reservoirs. |