Comprehensive Modeling of CO2 Sequestration in Syderiai Deep Saline Aquifer: Insights into Leakage, Geo-Mechanical Changes, and Geo-Chemical Impacts

This paper presents a comprehensive study on the feasibility and implications of a CO2 injection simulation in the Syderiai deep saline aquifer of Lithuania, focusing on leakage, geo-mechanical aspects, and geo-chemical aspects. The Syderiai aquifer, characterized by its sandstone formation covered by shaly rocks, is considered a potential site for CO2 geological storage in Lithuania. Using 3D mechanistic models developed in T-navigator software, we conducted extensive simulations to analyze CO2 storage behavior and associated impacts. The leakage study examines various scenarios to assess the impact of fracture permeability, layer-wise heterogeneity, and fracture position on CO2 injection and leakage volumes. Results indicate that while fracture permeability influences CO2 migration dynamics, its impact on both free and dissolved CO2 leakage volumes is minimal, highlighting that leakage behavior is more dependent on the presence of fractures than their permeability. Geo-mechanical analysis reveals the effects of CO2 injection on the bulk modulus and shear modulus of sandstone and shale formations, highlighting changes in compaction and cementation. The geo-chemical study was performed using TOUGHREACT software V4.13-OMP to investigate the distribution of pH, porosity change, and free CO2 over 1000-years following 10-year CO2 injection. Results demonstrate the acidifying effect of CO2 injection and its implications for the caprock–reservoir interface over time. The findings offer valuable perspectives on the feasibility and consequences of CO2 geological storage in the Syderiai deep saline aquifer, highlighting the importance of incorporating leakage, geo-mechanical aspects, and geo-chemical aspects for implementing efficient CO2 storage.