Research on the Cyclic Injection and Production Characteristics of a Synergistic CO 2 Sequestration and Compressed Flue Gas Energy Storage System Based on Aquifers

ABSTRACT This study proposes an aquifer‐based compressed flue gas energy storage system integrated with CO 2 capture and sequestration, utilising the gas‐trapping characteristics of anticlinal geological structures. A multi‐physics‐coupled transient model (flow–phase–saturation–geochemical reactions) was developed to analyse the dynamic evolution of cyclic injection–production processes. The dynamic behaviour of bottomhole pressure, bottomhole temperature and gas‐phase saturation was evaluated under specified operating conditions. The overall CO 2 storage capacity during cyclic operation was quantified. Energy and exergy efficiencies of the compressed flue gas were assessed over a single injection–production cycle. Numerical simulations show that pressure and temperature in the wellbore vary cyclically, gas saturation becomes evenly distributed and CO 2 storage capacity increases cumulatively. Energy efficiency decays and stabilises, whereas exergy efficiency improves steadily and approaches equilibrium. The effects of inter‐well spacing and aquifer permeability on system performance were also examined. Inter‐well spacing is positively correlated with CO 2 sequestration but negatively correlated with exergy efficiency. Increased permeability reduces pressure differentials, enhances temperature gradients, promotes uniform gas distribution and increases the share of geochemical CO 2 storage.