Long-term CO2 sequestration mechanisms and influence of injection mode in Zhujiang Formation of Pearl River Mouth Basin

In this paper, the mechanisms of long-term CO₂ sequestration and the effects of injection modes (including injection temperature, injection rate and injection cycle) in Zhujiang Formation characterized by high porosity and permeability were investigated using the numerical simulation method. Simulation results showed that more than 88% of the injected CO₂ would exist in a supercritical state during the injection period and more than 79% of CO₂ would be sequestrated in the reservoir by mineral trapping after 5,000 years. Eventually, the distribution shape of SC-CO₂ was a quarter funnel near the injection well, while the distribution shapes of dissolved and mineralized CO₂ were both one quarter rotunda. During the long-term CO₂ sequestration in Zhujiang Formation, the dissolved minerals were anorthite, chlorite and smectite in turn, while the top three main precipitated minerals were calcite, dawsonite and albite. Moreover, higher injection temperature leads to a higher mineral tapping and more dissolved/precipitated minerals. While higher injection rate reduces the mineral tapping and total amount of dissolved/precipitated mineral. Compared to injection temperature and injection rate, the injection cycle has little effect on the CO₂ phase evolution and mineral dissolution/precipitation process. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.