## 1 Introduction
### Experimental Results and Discussion
Furthermore, the light color of the cross-section of the inlet and outlet indicated a low remaining oil saturation in the model after supercritical multi-source, multi-component thermal fluid displacement. A comparison of the inlet and outlet cross-sections revealed similar remaining oil saturations due to the high sweep range and displacement efficiency. Therefore, it can be concluded that supercritical multi-source, multi-component thermal fluids have significant potential in offshore heavy oil development. As can be seen from Figure 4 and Table 5, the displacement efficiency of Experiments 1, 4, 7, and 13 were 59.87%, 73.48%, 78.52%, and 85.15%, respectively. It can be seen that compared with steam flooding, supercritical water flooding, and supercritical water and gas, the development effect of supercritical multi-source, multi-component thermal fluid flooding was better. In addition, it can be seen from Table 4 that the color of the end face of the entrance and exit of Experiment 13 is lighter than that of Experiments 1, 4, and 7, indicating that Experiment 13 has the lowest remaining oil saturation. By comparing the oil displacement efficiency, heat utilization rate, and core end color of Experiment 1, and Experiment 4, it can be seen that supercritical water displacement effect is better than steam. The reason is that supercritical water has a stronger effect on the upgrading of heavy oil, and it is not easy to produce overlap breakthrough phenomenon. Compared with steam, supercritical water thermal cracking reaction can significantly \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Experiment** & **1** & **4** & **7** & **13** & **14** & **15** & **16** \\
**Number** & & & & & & & \\ \hline \multirow{3}{*}{Injected fluid} & \multirow{3}{*}{steam} & \multirow{3}{*}{Supercritical water} & \multirow{3}{*}{supercritical water + N\({}_{2}\)} & supercritical multi-source multi-component component thermal fluid thermal fluid thermal fluid thermal fluid thermal fluid \\  & & & & & & \\ \hline \multirow{3}{*}{Inlet cross-section} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} \\  & & & & & & \\ \hline \multirow{3}{*}{Outlet cross-section} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} & \multirow{3}{*}{Steam} \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cross-sectional states of inlet and outlet of different injected fluids. reduce the viscosity, density and molecular weight of heavy oil, and inhibit the formation of coke. In addition, compared with steam, supercritical water can dissolve weakly polar substances in heavy oil effectively, resulting in miscible flooding effect. By comparing the results of Experiments 13 and 4 (Figure 4 and Table 5), it can be seen that the presence of supercritical N\({}_{2}\) + CO\({}_{2}\) is helpful to improve the oil displacement efficiency and relative heat utilization rate of supercritical water flooding and reduce the remaining oil saturation. Therefore, supercritical N\({}_{2}\) and supercritical CO\({}_{2}\) play an important role in heavy oil production. In addition, it can be seen from Figure 5 that after the injection of 1.5 PV, the advance of the supercritical multi-source, multi-component thermal fluid front is slower than that of the supercritical waterfront. Therefore, the injection of supercritical N\({}_{2}\) and CO\({}_{2}\) can effectively inhibit the breakthrough of supercritical water. This is due to the large amount of supercritical CO\({}_{2}\) dissolved in heavy oil, resulting in heavy oil expansion, and reducing the viscosity, density, and molecular weight of heavy oil. Figure 5: Temperature field diagram of each experiment.