Carbon storage estimation of the Red Beds of Hazlehurst based on post-stack seismic inversion, southeastern Georgia

The Red Beds of Hazlehurst (RbH) in the southeastern United States, which includes the states of Georgia and South Carolina, is a saline formation identified with the potential to store hundreds of gigatons of CO₂. Despite its large storage capacity, the limited characterization of the subsurface structures and stratigraphic units of RbH constrains a detailed understanding of reservoir properties. Hence, a detailed subsurface characterization is needed to understand properties such as porosity, permeability, lithology variation, and seals of the RbH formation. This study applied post-stack seismic inversion to characterize the RbH formation in southeastern Georgia. Our methodology used 2D seismic profiles with two existing wells to build P-acoustic impedance and porosity cross-section models of the RbH formation. Using these models, we identified potential CO₂ storage intervals within the formation that show potential for CO₂ storage. These attributes were used to develop porosity predictions from empirical relationships between the derived P-acoustic impedance and well log analysis. The P-acoustic impedance (AI) model suggests that the upper part of the RbH, characterized by lower acoustic impedance, corresponds to porous rocks, which is the most promising zone for CO₂ storage. Porosity values derived from geophysical logs range from 4% to 10% in the most promising reservoir zones. These low porosity values suggest that the RbH is a tight formation, due to shale dominance, which could affect the storage capacity and reservoir quality. An increase in acoustic impedance was observed in the transition zones between RbH and the Coastal Plain rocks. The low porosity is associated with the presence of igneous rock, which can serve as a seal, preventing CO₂ from migrating into the younger overlying Coastal Plain sediments. The CO₂ storage estimate of the RbH calculated range from 8.53 to 27.67 megatons. This work supports subsurface characterization in Georgia and contributes to storage capacity initiatives for regional decarbonization within the Southeast Regional Carbon Sequestration Partnership (SECARB).