This study summarises the results of our first-order conceptual feasibility study. We investigated the concept of injecting and circulating CO2 for geothermal energy production from potential CO2 storage formations (saline aquifers) in the Western part of the Swiss Molasse Basin (“Muschelkalk” and “Buntsandstein” formation). Old 2D-seismic data indicates a potential anticline structure in the investigated area. Ultimately, this conceptual study helps assessing the potential storage capacity range and will be beneficial for future economical assessments.
The interpretation of the intersected 2D seismic profiles reveals an anticline-dominated geological model with a surface area of 4.35 x 4.05 km2. For studying the dynamic reservoir behaviour during the CO2 circulation, we analysed: (1) the petrophysical rock properties geostatistically to account for heterogeneity, (2) the physics of a two-phase (CO2 and brine) fluid system, including the relative permeability characterization, fluid model composition, the residual and solubility CO2 trapping, and (3) the thermophysics properties of resident-formation brine and the injected CO2 gas.
Our study represents a first-order estimation of the expected CO2 storage capacity range at a possible anticline structure in the Middle – Lower Triassic formation in the Western part of the Swiss Molasse Basin. Additionally, we investigated the effect of different well locations and set-ups and assessed the expected production rates and resulting well flow regimes in a conceptual CO2 production well for geothermal energy production. At the point of writing this abstract, the study is still ongoing and not yet completed. Nonetheless, our preliminary results indicate that both reservoirs combined can take up to 2 – 3 Mt of CO2 over multiple decades of CCUS operation. From our results, we can clearly identify limiting factors on the overall storage capacity, such as for example the reservoir fluid pressure distribution and lateral diffusion.