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Active CO2 reservoir management for sustainable geothermal energy extraction and reduced leakage



Subsurface storage space is gaining recognition as a commodity for industrial and energy recovery operations. Geologic carbon dioxide (CO2) sequestration (GCS), wherein supercritical CO2 is injected into subsurface storage space, is under broad development in sedimentary reservoirs – particularly for hydrocarbon production, which uses supercritical CO2 as part of a carbon capture utilization and sequestration (CCUS) scheme. A novel CCUS operation is presented whereby we investigate the staged deployment of a coupled geothermal energy extraction (GEE)-GCS operation in geothermal sedimentary reservoirs that re-circulates extracted fluids. We identify sedimentary resources of the continental USA that have significant temperature at depths suitable for GCS. To predict the impact of a GEE-GCS operation, a reservoir-scale semi-analytical model is used to simulate brine and CO2 migration through existing leakage pathways. With the goal of integrating GEE and GCS, a well-site design exercise is undertaken, where we develop an idealized configuration for CO2 and brine production/reinjection wells. Results show potential geothermal sedimentary reservoirs suitable for GEE deployment exist in the continental USA; however the characteristics of each site should be investigated through a first stage GEE-operation to determine GCS capacity. Our active CO2 reservoir management simulations demonstrate a decrease in injection and reservoir overpressures, a reduced migration of CO2 within the reservoir during active injection/extraction, and a reduced risk of brine and CO2 migration. With the use of the developed concentric-ring well pattern, we demonstrate the longevity of thermal productivity from an ideal GEE site, while providing sufficient CO2 storage volume and trapping to act as a sequestration operation. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd