부산대학교 도서관

CO2 injection significantly impacts the saline aquifer’s pressure system, with overpressure in the caprock and fluctuations in inter-layer pressure differentials threatening the integrity of the caprock and wellbore, thereby affecting sequestration effectiveness and environmental safety. To address this, a numerical model for CO2 saline aquifer sequestration was established and validated, aiming to investigate relevant control methods. The study simulated a typical sequestration process to understand the spatial and temporal evolution of the aquifer’s pressure system. Various engineering factors were analyzed, and the impact of coupling injection modes on the pressure system was explored. Results showed that CO2 injection led to widespread overpressure in the reservoir and cap layer, with the overpressure in the caprock being lower than that in the reservoir. After ceasing injection, the pressure system gradually returns to its initial state. The pressure response of the caprock exhibits significant hysteresis, leading to the dynamic evolution of inter-layer pressure differentials. The use of horizontal well, extended injection section, and pre-modified surrounding reservoir can mitigate caprock overpressure and inter-layer pressure differential fluctuations. The coupling effects of favorable factors were analyzed, with the HRC mode demonstrating the best control over caprock overpressure, while also providing effective control of inter-layer pressure differentials. The HRP mode is optimal for controlling inter-layer pressure differentials, although it leads to an increase in caprock overpressure amplitude. It is recommended to select an appropriate injection mode based on the risk levels of caprock and wellbore integrity at the sequestration site.