## 3 Generation of the Initial Data Set  
### Establishment of the CSS Simulation Model  
The STARS numerical simulator from CMG was used to build a typical CSS simulation model. The calculated COP of horizontal CSS wells under different geological, well, and operational conditions by the simulation model served as the initial data sets for the subsequent PA-LM model.  
Figure 2 shows the established three-dimensional reservoir model and the horizontal well model. Table 1 shows the average values of the reservoir parameters, oil viscosities at different temperatures, oil and water relative permeability curves, heat transfer parameters of rocks and fluids, and operational parameters used in the CSS simulation model.  
To ensure the accuracy of the established CSS simulation model and lay a solid foundation for generating the initial data sets for the subsequent PA-LM model, the COP values (primary production and the first cycle of the CSS process) of the horizontal CSS well were matched by modifying the model parameters, such as oil and water relative permeabilities, reservoir parameters, and heat transfer parameters of rocks and fluids within a reasonable range. The history matching results from Figure 3 indicate that the successful modification of the aforementioned parameters resulted in a satisfactory match for the horizontal CSS well.  
Figure 1: The workflow of the methodology combining the PA and LM model for predicting the COP of CSS horizontal wells.  
Figure 2: The established three-dimensional reservoir model and the horizontal well model: (**a**) three-dimensional reservoir model; (**b**) the horizontal well model.  
\begin{table}
\begin{tabular}{c c} \hline
**Reservoir Parameters** & **Values** \\ \hline Reservoir porosity & 0.3 \\ Reservoir permeability (MD) & 3000 \\ Initial reservoir temperature (\({}^{\circ}\)C) & 54 \\ Oil saturation & 0.6 \\ \hline
**Well Parameters** & **Values** \\ \hline Well spacing (m) & 200 \\ Well distance (m) & 200 \\ \hline
**Heat Transfer Parameters of Rocks and Fluids** & **Values** \\ \hline Rock volumetric heat capacity (kJ/(cm\({}^{3.\circ}\)C)) & \(2.575\times 10^{6}\) \\ Reservoir rock thermal conductivity (kJ/(cm\(\cdot\)min\(\cdot\)\({}^{\circ}\)C)) & \(1.634\times 10^{5}\) \\ Oil phase thermal conductivity (kJ/(cm\(\cdot\)min\(\cdot\)\({}^{\circ}\)C)) & \(9.77\times 10^{3}\) \\ Water phase thermal conductivity (kJ/(cm\(\cdot\)min\(\cdot\)\({}^{\circ}\)C)) & \(5.99\times 10^{4}\) \\ Gas phase thermal conductivity (kJ/(cm\(\cdot\)min\(\cdot\)\({}^{\circ}\)C)) & \(1.9\times 10^{3}\) \\ \hline
**Operational Parameters** & **Values** \\ \hline Soaking time (day) & 5 \\ Steam injection volume (m\({}^{3}\)) & 6600 \\ Steam injection rate (m\({}^{3}\)/day) & 300 \\ Steam quality & 0.4 \\ liquid production rate (m\({}^{3}\)/day) & 90 \\ Steam temperature (\({}^{\circ}\)C) & 340 \\ \hline
**Oil Viscosities at Different Temperatures** \\ \hline
**Temperature (\({}^{\circ}\)C)** & **Viscosities (mPa-s)** \\ \hline
20 & 74,704.94 \\
50 & 3969.97 \\
100 & 198.82 \\
150 & 35.19 \\
200 & 11.84 \\
250 & 5.66 \\
300 & 3.32 \\ \hline \multicolumn{3}{c}{**Water and Oil Relative Permeabilities**} \\ \hline
**S\({}_{\textbf{w}}\)** & **K\({}_{\textbf{rw}}\)** & **K\({}_{\textbf{ro}}\)** \\ \hline
0.305 & 0.000 & 1.000 \\
0.373 & 0.006 & 0.738 \\
0.427 & 0.012 & 0.572 \\
0.497 & 0.036 & 0.380 \\
0.505 & 0.045 & 0.360 \\
0.533 & 0.060 & 0.292 \\
0.588 & 0.080 & 0.173 \\
0.626 & 0.100 & 0.104 \\
0.720 & 0.147 & 0.000 \\
1.000 & 1.000 & 0.000 \\ \hline \end{tabular}
\end{table}
Table 1: The basic parameters used in the CSS simulation model.  
Figure 4: The calculated COP of the horizontal CSS well at various conditions: (**a**) well and geological conditions; (**b**) operational conditions.  
Figure 3: History matching of the COP values of the primary production and the first cycle of the CSS process of the horizontal CSS well.