Integrated reservoir and production system modeling of geothermal energy extraction at the Aquistore CCS site in Canada

Mitigating the global climate crisis is the greatest challenge facing humanity thiscentury. The transition of current energy systems towards carbon-neutral energyis inevitable. Renewable energy sources, particularly those that are both baseload-and dispatch-capable, such as geothermal energy, are essential to replace currentenergy systems that emit large amounts of CO2. In addition, permanent isolationof CO2 from the atmosphere, using carbon capture and sequestration (CCS), isindispensable to limit global warming to 1.5°C.To enable the full potential of geothermal energy extraction and of CCS, theirefficiencies need to be improved. One possibility is to integrate both technologies.Using CO2 as the geothermal energy extraction fluid approximately doubles energygeneration rates, compared to conventional, brine-based geothermal systems underour base-case conditions. Such CO2 Plume Geothermal (CPG) systems reinjectthe produced CO2, eventually sequestering all CO2 underground. Extracting thegeothermal energy from the CCS reservoir results in additional CO2 storage poten-tial, as, for example, the CO2 density increases and the overall reservoir pressuredecreases. The CPG-generated heat, electricity, and/or revenue could “subsidise”CCS operations. Consequently, CPG could increase both the geothermal energyand the CCS capacities.Our CPG feasibility study combines an integrated production system modelingapproach with a history-matched reservoir model of an active CCS site (Aquistore,Canada). The integrated modeling approach is used to account for all relevantprocesses, from well-bore pressure and temperature drops to multi-phase, multi-component fluid flow in the reservoir to fluid separation, power generation, andcontinuous with reinjection of CO2 at the land surface, in a fully implicit matter.Our results suggest that stable CO2 circulation, extracting geothermal energybetween the underground CO2 plume in the saline reservoir and the land surface,is possible. Furthermore, we see additional CO2 storage potential, caused by thecirculation of CO2. Our simulations indicate that Aquistore may provide a uniqueopportunity for pioneering a CPG field test.