PROBABILISTIC EVALUATION MODELING OF GEOLOGIC CARBON DIOXIDE STORAGE CAPACITIES OF TARGET GEOLOGIC FORMATIONS AT A PROSPECTIVE STORAGE SITE IN THE JANGGI BASIN, KOREA

A series of geologic formation modeling, carbon dioxide (CO₂) behavior prediction modeling, and performance evaluation modeling was performed sequentially to estimate the geologic CO₂ storage capacities of target geologic formations at a prospective storage site in the Janggi Basin, Korea. The prospective storage site is composed of the basement, Janggi Conglomerate, Seongdongri Formation, and Noeseongsan Basalt in ascending order. The lower Reservoir (Res.) 1 and upper Reservoir 2, which are separated by a tuff layer (intra seal), of the Janggi Conglomerate are selected as target geologic formations for geologic CO₂ storage at the site because of their proper depth for supercritical CO₂ condition (800 m below the ground surface) and hydrogeological properties (high porosity and permeability). The results of the performance evaluation modeling, which is based on probabilistic Monte Carlo simulation, show that the storage densities (CO₂ masses stored per unit volume of geologic formation) of the free fluid phase of CO₂ are significantly higher than those of the aqueous phase of CO₂ in Res. 1 and Res. 2. On the other hand, the storage densities of both free fluid and aqueous phases of CO₂ in Res. 2 are slightly higher than those in Res. 1 due to the larger porosity of Res. 2. The theoretical (potential) storage capacities of the free fluid phase of CO₂ are significantly higher than those of the aqueous phase of CO₂ in Res. 1 and Res. 2. On the other hand, the theoretical storage capacities of both free fluid and aqueous phases of CO₂ in Res. 1 are significantly higher than those in Res. 2 due to the larger volume of Res. 1. However, the effective (realistic) storage capacities of the free fluid phase of CO₂ are nearly equal to those of the aqueous phase of CO₂ in Res. 1 and Res. 2. This arises because the storage efficiency factors of the aqueous phase of CO₂ are much higher than those of the free fluid phase of CO₂ in Res. 1 and Res. 2. On the other hand, the effective storage capacities of both free fluid and aqueous phases of CO₂ in Res. 1 are significantly higher than those in Res. 2 due to the larger volume of Res. 1. This work was supported by the Korea CCS 2020 Project of the Korea CCS R&D Center (KCRC) funded by the National Research Foundation (NRF), Ministry of Science, ICT and Future Planning, Republic of Korea, under grant no. NRF-2015M1A8A1048896.