Development of an Integrated Numerical Simulation System for Geologic Carbon Dioxide Storage into a Prospective Storage Site in the Gyeongsang Basin, Korea: from Geologic Modeling to Risk Analysis Modeling

An integrated numerical simulation system (package) was developed to predict and analyze geologic carbon dioxide storage. The integrated numerical simulation system consists of the four units such as three-dimensional geologic modeling of target geologic formation systems, prediction modeling of behavior (trapping mechanisms, leakage mechanisms) of carbon dioxide, evaluation modeling of three major performances (storage capacity, seal capacity, injection capacity) of target geologic formation systems, and analysis modeling of leakage risk of deep groundwater and carbon dioxide. This integrated numerical simulation system was then applied to a prospective storage site in the northern part of the Gyeongsang Basin, Korea. A series of three-dimensional geologic modeling of the target geologic formation system at the site was performed first using GOCAD (Paradigm, 2012). The geologic modeling results reveal that the site is composed of the five sedimentary geologic formations such as the Nakdong Formation, Hasandong Formation, Jinju Formation, Iljik Formation, and Hupyungdong Formation in ascending order, and a thick sandstone layer in the Hasandong Formation can be a target formation for geologic carbon dioxide storage. Above the target formation, three more sandstone layers (aquifers) exist, and carbon dioxide can leak into these aquifers. A series of prediction modeling of behavior of carbon dioxide injected into the target formation under various carbon dioxide injection amounts was then performed using TOUGH2 (Pruess et al., 1999). The prediction modeling results show that injected carbon dioxide can not only be stored as a free fluid phase by hydrodynamic trapping but can also be stored as an aqueous phase by solubility trapping. As a result, the carbon dioxide plume (free fluid phase of carbon dioxide) moves upward by buoyancy, whereas the carbon dioxide dissolved groundwater (aqueous phase of carbon dioxide) moves slowly downward by gravity. Finally, a series of analysis modeling of leakage risk of deep groundwater and carbon dioxide through abandoned wells under various locations was performed using CO2-LEAK (Kim, 2012). The analysis modeling results show that carbon dioxide injection can cause deep groundwater (brine) and carbon dioxide (both free fluid and aqueous phases) leakage into the overlying aquifers through the abandoned wells. In that case, brine leaks first, aqueous phase of carbon dioxide then leaks, and free fluid phase of carbon dioxide leaks finally. This work was supported by the Korea CCS 2020 Program funded by the National Research Foundation (NRF), Ministry of Science, ICT and Future Planning, Republic of Korea.