Sedimentary Basin CO2-Driven Geothermal Utilization Systems: the Impact of the Geological Heterogenity

Prior reservoir modeling for CO2-driven geothermal utilization systems has implemented a classical grid-based approach and assumed homogeneous reservoirs with no variation of reservoir properties (e.g., permeability, porosity) in the aquifer. But understanding the variations in these parameters is critical for the flow characterization and heat transport, because they can be major controls on reservoir production. We implemented and examined the spatial variability of petrophysical properties using the IC-FERST reservoir simulator, an open-source code that uses a double control volume finite element method, and non k-orthogonal meshes beneficial for a more accurate representation of geologic heterogeneity with fewer mesh elements. We built a 3D geological model that represents a deep and thin aquifer with multiple layers. We simulated CO2 injection and production via a well doublet, and we implemented mathematically defined . Results show that the cold injected fluid flows faster through the layers and zones with a higher permeability and porosity, while the low permeability and low porosity layers and zones exchange heat with the CO2 through thermal diffusion.