Impacts of injection temperature on the CO2 injection capacity in the different sloping formations.

The CO2 injection capacity directly affects the CO2 storage efficiency. Injection temperature and formation sloping degree affect the CO2 injection capacity. Based on the actual geological conditions of the Shiqianfeng Formation in the Ordos Basin of China, a three-dimensional (3D) simulation model was established to evaluate pressure, temperature, CO2 spatial distribution, and injection amount. A total of 17 simulation schemes were carried out using the TOUGH2-ECO2N fluid property module. The results showed that the injection temperature had a significant impact on the CO2 injection capacity in the different sloping degree formations. Increasing the injection temperature resulted in increased formation pressure, CO2 gas phase, dissolved phase, and total injection amount, while decreasing the CO2 concentration, and the formation pressure changed obviously with the formation sloping degree. The larger the formation sloping degree was, the less the CO2 injection amount. Higher injection temperature and smaller sloping degree formation were more favorable for CO2 injection, and the CO2 injection capacity was stronger, signaling that it should be selected to store CO2 in the future.