A Study on Effect of Number of Low‐Permeability Layers on Geological Carbon Sequestration in an Open Aquifer

The use of fossil fuels to fulfill energy demand is responsible for CO2 emissions, resulting in global warming and climate change. Despite the expansion in renewable energy sources, energy combustion and industrial processes caused a 0.9% increase (321 Mt) in global CO2 emissions to a record high of 36.8 Gt in 2022. Carbon capture and sequestration (CCS) technology can allow the use of fossil fuel without damaging the environment by storing CO2 underground, paving the way for a sustainable, low‐carbon future. Without fracturing, both homogeneous and low‐permeability aquifers can safely accommodate injected CO2. This study investigates the effect of low‐permeability layers composed of sandstone and shale layers on the capacity and performance of CO2 storage in open saline aquifers. The CO2 migration, dispersion, and reservoir pressure variations have been numerically investigated in a computational domain representing the Utsira Formation in Sleipner CCS project. In a homogeneous aquifer, rapid vertical migration results in 65% of the injected CO2 accumulating at the top layer after 30 years. However, the presence of four low‐permeability layers reduces this accumulation to 58% over the same period, demonstrating enhanced trapping efficiency. Long‐term simulations indicate that CO2 accumulation at the top surface increases to 75% of the total injected volume over 80 years. CO2 dissipates and migrates over time, resulting in a decrease in surface pressure. Pressure analyses reveal that the peak injection‐induced pressure remains within the fracture pressure limit (20–25 MPa), ensuring safe storage. After 30 years of injection, pressure at the top surface drops by 0.27 MPa (2.72%) within 2 years post‐injection and continues to decrease gradually. This investigation contributes to a better understanding of the dynamics of CO2 storage in open saline aquifers, thereby facilitating the development of effective CO2 sequestration strategies. © 2025 Society of Chemical Industry and John Wiley & Sons, Ltd.