A multi-stage SRL-based framework for offshore CO2 storage assessment: Application to the Korean continental shelf

Identifying reliable and scalable offshore CO₂ storage sites requires systematic workflows that connect geological screening with project maturity assessment. In this study, we present a nine-stage evaluation framework that integrates Storage Readiness Levels (SRL), deterministic filtering, Common Risk Segment (CRS) analysis, semi-quantitative scoring, and milestone-based maturity tracking into a unified methodology. The approach is implemented in a modular Excel platform designed to ensure transparency, reproducibility, and applicability across variable data conditions. We applied this framework to major offshore basins surrounding the Korean Peninsula, including the Yellow Sea, South Sea, and East Sea. Initial screening (SRL1–2) identified four basins with adequate depth, sealing systems, and storage potential. CRS-based risk classification (SRL3) narrowed candidates to the Eastern Gunsan Basin (EGB) and the southwestern Ulleung Basin shelf (SWSUB). Quantitative scoring and structure-scale analysis (SRL4) further differentiated prospects within the SWSUB, where six Miocene prospects advanced to SRL5 due to robust seismic–well control and 3D geologic modeling. Among them, one depleted gas field demonstrates conditional SRL6 maturity supported by dynamic simulation results but requires additional geomechanical and monitoring design. The case study reveals significant variability in basin maturity and highlights key data gaps limiting site progression. More broadly, the SRL-based workflow provides a practical path for harmonizing site screening, risk evaluation, and readiness assessment—offering a transferable tool for offshore CCS planning in regions with heterogeneous datasets. This work demonstrates that structured readiness frameworks can accelerate identification of high-potential CO₂ storage opportunities and improve communication with regulatory and industrial stakeholders.