Evaluating the Effect of CO2-Brine-Rock Interactions on Storage Capacity and Containment in Saline Aquifers in the Niger Delta Using Coupled Wellbore-Reservoir Modelling

Abstract According to a report by the International Energy Agency, global energy demand grew significantly in 2023 nearly doubling the average growth rate since 2010. This increase has intensified the release of anthropogenic CO2 into the atmosphere, accounting for about 80% of global greenhouse gas emissions. Similarly, emissions from fossil fuels used in energy production and consumption have pushed atmospheric CO2 concentrations to an alarming 422 ppm, with projections suggesting levels could rise to 600–700 ppm by the end of this century. Such an increase could result in a global temperature rise of 4.5–5°C, leading to severe environmental and economic consequences. To address this, carbon capture and storage (CCS) has emerged as a promising solution alongside energy efficiency improvements, renewable energy adoption, and large-scale afforestation. CCS involves capturing CO2 from fixed-point sources and injecting it into deep geological formations for long-term storage. Saline aquifers are particularly attractive for CCS due to their large regional extent and high porosity, offering substantial storage capacity. However, challenges such as aquifer structural uncertainty, injectivity loss, and leakage risks must be resolved to ensure the technology's feasibility and safety. This paper focuses on evaluating the impact of CO2-brine-rock interactions on the storage capacity and containment potential of saline aquifers in the Niger Delta. Using formation data from the region, a coupled wellbore-reservoir modelling was conducted with PROSPER and CMG software to simulate various injection scenarios and assess their effects on key parameters such as porosity, permeability, caprock integrity, and brine chemistry. Initial findings reveal that CO2 injection triggers complex chemical interactions that enhance storage capacity through mineral trapping but may reduce injectivity due to pore blockage caused by precipitation. Caprock integrity analysis shows that Niger Delta formations possess adequate sealing capacity, with minimal leakage risks under controlled injection rates. Residual and solubility trapping mechanisms further contribute to long-term CO2 containment. This paper provides valuable insights into the dynamic behaviour of CO2 storage in saline aquifers, offering a deeper understanding of site-specific factors that influence injectivity and containment. The results will guide the optimisation of CCS strategies in the Niger Delta, supporting the region's efforts to reduce carbon emissions and contribute to global climate goals.