Comprehensive site screening and selection for offshore CO2 storage in the Early Miocene formations of the eastern Gunsan Basin, Yellow Sea

Abstract

We employed a site screening framework to select potential CCS sites within the Early Miocene formations of the eastern Gunsan Basin in the Yellow Sea, offshore South Korea, by incorporating subsurface data. The site screening process, comprising stratigraphic and structural interpretation, gross depositional environment mapping, and common risk segment mapping, revealed three potential areas for CO₂ geological storage: SA1, SA2, and SA3 in the north, center, and south, respectively. SA1 was the most favorable site, considering its substantial sand potential and geologically stable environment. Prospective CO₂ storage resources for SA1 were estimated using geological static modeling and the CO₂-SCREEN tool, yielding a best estimate (P50) in the range of 420–459 MtCO₂. Pressure-constrained storage resource was also evaluated using EASiTool V5.0, which accounts for realistic injectivity and operational limitations, resulting in a more conservative P50 estimate of 91.9 MtCO₂. This study highlights significant potential for CO₂ storage in the Early Miocene formation of the eastern Gunsan Basin, to secure additional CO₂ storage resources and achieve the 2030 nationally determined contribution and 2050 net zero greenhouse gas emission targets. The applied site screening framework can serve as a transferable approach for evaluating CO₂ storage in offshore basins globally.