Geological Characterization and CO2 Storage Potential of the Newly Identified Red Beds of Hazlehurst Beneath the Georgia and South Carolina Coastal Plain

The states of South Carolina and Georgia emitted ~100 million tons of CO₂ in 2018 from point sources. Integration and interpretation of subsurface data enable us to identify a previously unrecognized, regionally extensive, and thick (up to 450 m) sedimentary sequence - the Red beds of Hazlehurst (RbH) - as a potential saline reservoir for CO₂ storage in the southeastern U.S. Based on the renewed stratigraphic framework and structural interpretation of the RbH, we analyzed detailed well logs and the depositional environments to provide regional scale estimations of the storage resource in the RbH. The volumetric results suggest the effective storage area (~85,000 km²) has a maximum resource potential for 586 gigatons anthropogenic CO₂. Petrophysical measurements suggest the permeability of RbH ranges from 0.001 to 48 mD, and the porosity ranges from 11.1% to 18.4%. Residual/capillary trapping and solubility trapping act as the main trapping mechanisms for long term storage and prevent vertical migration of CO₂ into the shallow freshwater aquifers. Due to the heterogeneity observed in geophysical logs and the scarcity of well penetrations, it is difficult to select ideal injection sites at this stage. Additional subsurface data such as the caprock entry pressure will be helpful to better characterize the seal integrity of the system.