1-2 Application of Noble Gas Geochemistry to Characterize Deep Crustal Fluids in Geological Reservoirs for Carbon Capture and Storage in the Southeastern USA

Session: Energy Geology

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Carbon capture and storage (CCS) is a crucial industrial scale mitigation strategy for reducing anthropogenic CO₂ emissions in the atmosphere, with the goal of long‑term isolation of CO₂ within deep geological formations (IPCC 2005). Federal incentives such as the 45Q tax credit are a major driver accelerating CCS deployment, particularly in regions like the Southeastern U.S. where suitable and extensive deep saline formations occur near large industrial emitters. The Southeast Regional Carbon Sequestration Partnership (SECARB) conducted extensive regional characterization, identifying deep and extensive saline formations across the southeast suitable for long‑term CO₂ storage. The SECARB Phase III Projects in Mississippi and Alabama demonstrated secure CO₂ injection into Upper and Lower Cretaceous Formations. The growing interest in CCS development in the region is testament to SECARB’s Success. For routine CCS deployment, it is important to determine the security and fate of the stored CO₂ and to detect any leakage or migration from storage reservoirs. A number of geochemical monitoring tools have been developed to monitor the fate and migration of the injected CO₂, but their effectiveness is enhanced greatly by robust geochemical baselines established prior to CO₂ injection, e.g., Utley et. al. (2023).  Monitoring applications utilizing traditional carbon and oxygen isotopes often lack sensitivity as effective tracers of injected CO₂ for reasons including overlapping isotopic compositions between injected and native CO₂. Noble gases, by contrast, are chemically inert and possess distinct isotopic signatures that reflect contributions from atmospheric, crustal, mantle, hydrologic, and anthropogenic sources. Recent studies (Gilfillan et.al., 2008; Györe et.al., 2017; Utley et.al., 2023) demonstrate their effectiveness in tracing CO₂ behavior in geologic reservoirs, while consistently highlighting the scarcity of pre‑injection noble‑gas datasets. This study aims to develop strategies and applications of CCS reservoir monitoring techniques by integrating He, Ne, Ar, Kr, and Xe isotopes with stable isotopes, characterizing deep crustal fluid sources, migration pathways, and pre-injection baseline conditions. The new data will also have applications for understanding the flow patterns and recharge rates for deep crustal fluids of the Southeastern US. Overall, the outcomes will provide a foundation for improved deep‑fluid sampling, refined noble‑gas extraction and purification, and more robust analytical workflows, ultimately expanding the CCS monitoring toolkit and strengthening the scientific basis for long‑term geologic CO₂ storage.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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