## 3 ROP Prediction Based on the Random Forest Machine Learning Model
### Factor Analysis
An analysis of the factors affecting the drilling speed in well Fu39 is shown in Figure 5. The main factors influencing the drilling speed of this well are the drilling fluid equivalent density, annular pressure, inlet flow rate, and pump speed, with the drilling fluid equivalent density having the highest feature importance share, around 0.39. According to the mechanistic model, the choice of the appropriate drilling fluid density can make it easier for the drill bit to penetrate the subsurface, reducing the risk of the drill bit becoming stuck or failing. Therefore, the selection of equivalent density is crucial for maintaining a stable drilling process. In the model, this means that we should pay close attention to the equivalent density because it has a significant impact on the drilling speed and can significantly change the drill bit's penetration into the formation. Figure 4: Correlation matrix diagram between the drilling parameters. Other important factors include the annular pressure, inlet flow rate, and pump speed. Annular pressure refers to the pressure of the drilling fluid inside the wellbore, which affects the cuttings' transport and wellbore stability. Adequate annular pressure helps to maintain wellbore stability and prevents issues like wellbore collapse and bit sticking. Inlet flow rate refers to the speed at which the drilling fluid enters the wellbore through the drill bit and affects the cuttings' removal efficiency. A sufficient inlet flow rate can effectively remove cuttings from the wellbore, preventing wellbore blockages and improving drilling efficiency. An inadequate inlet flow rate may lead to cuttings' accumulation at the bottom of the wellbore, reducing the drilling efficiency and potentially causing sticking. Pump speed refers to the rate at which the drilling fluid is pumped, directly impacting inlet flow rate and bottom hole pressure. Appropriate pump speed ensures an adequate inlet flow rate, maintains the required bottom hole pressure, and improves the drilling efficiency. Therefore, during on-site drilling operations, various parameters, especially those predicted as important by the model, should be considered comprehensively to ensure a safe and efficient mechanical drilling process. An inadequate parameter configuration can lead to drilling accidents, wellbore collapse, sticking, and other issues, increasing the risks and costs of drilling operations. A feature importance analysis of the factors influencing the drilling speed in well Kangtan2 is shown in Figure 6. The main factors affecting the drilling speed of this well are the drilling fluid equivalent density, standpipe pressure, viscosity, and drilling pressure, with the drilling fluid equivalent density having a feature importance share of over 0.6, significantly higher than the importance level of well Fu39. Through laboratory experiments on core samples taken at the same depth from both wells, it was found that the reservoir rock permeability in well Kangtong2 is higher. Additionally, according to the log interpretation data, this well has a complex formation pressure system, strong formation heterogeneity, and highly variable geological characteristics. It is influenced by factors such as the presence of argillaceous rocks, burial depth, and tight lithology. As a result, it exhibits a stronger dependence on the drilling fluid equivalent circulation density (ECD). Figure 5: Importance ranking of features affecting ROP in well Fu39.