# A Model-Based Intelligent Adjustment Method of Toolface for Bent-Housing Motor
## 4 Results and Discussions
### Tooflace Calculation Results of Drill String Dynamics Model  
According to the simulation calculation of the dynamics model, the trend of the tooflace change value over time under different well depth conditions is shown in Figure 6 when the bit is lifted from the bottom of the well by rotating the drill string to adjust the tooflace. The bit depths corresponding to the four curves in the figure are 1500 m, 2500 m, 3500 m, and 4500 m, respectively. During the tooflace adjustment process, the weight on bit is 0, the top drive rotation angle is 5 r, the top drive rotation speed is 10 r/min, and the initial circumferential displacement of each node on the drill string is 0. From Figure 6, it can be seen that when the drill string is rotated at a certain speed at the wellhead for a certain angle, the downhole tooflace changes accordingly, and after a certain period of time, the tooflace maintains a stable state again. When the well depth is 1500 m, the downhole tooflace begins to change after the wellhead drill string rotates for 2 s, and reaches a stable state after 30 s. After the tooflace stabilizes, the difference between the wellhead rotation angle and the tooflace change value is \((10\pi-30.21)\) rad, which is 69\({}^{\circ}\). When the well depth is 4500 m, the downhole tooflace begins to change after the wellhead drill string rotates for 30 s, and reaches a stable state after 400 s. After the tooflace stabilizes, the difference between the wellhead rotation angle and the tooflace change value is \((10\pi-12.40)\) rad, which is 1090\({}^{\circ}\). The above analysis results indicate that the greater the depth of the drill bit and the greater the friction between the drill string and the wellbore, the longer it takes for  
Figure 4: Framework of tooflace intelligent adjustment method for bent-housing motor. the downhole to return to a stable state, and the greater the difference between the change value of the downhole tooface and the rotation angle of the wellhead drill string. The variation curves of the downhole tooface change value with time under different top drive speed conditions at bit depths of 1500 m and 4500 m are shown in Figures 7 and 8. All the top drive rotation angles in the figure are 5 r. From Figures 7 and 8, it can be seen that the change value after the tooface finally reaches a stable state is independent of the top drive rotation speed when the tooface is adjusted. But, the higher the rotation speed of the top drive, the shorter the time it takes for the tooface to reach a stable state. As shown in Figure 7, when the depth of the drill bit is shallow and the friction between the drill string and the wellbore is small, the change value of the downhole tooface under the inertial action of the drill string rotation may even be greater than the rotation angle of the wellhead top drive at some time; but, eventually it will be smaller than the rotation angle of the wellhead top drive over time. As shown in Figure 8, when the drill bit depth is deeper and the friction between the drill string and the wellbore is greater, the downhole tooface slowly changes, and the change value of the downhole tooface during the entire adjustment process is smaller than the rotation angle of the wellhead top drive. Figure 5: Wellbore structure of the field data collection well. The variation curves of the downhole toolface change with time under different top drive rotation angles at drill depths of 1500 m and 4500 m are shown in Figures 9 and 10. All the top drive parameters have a rotation speed of 10 r/min, as seen in the figure. From Figures 9 and 10, it can be seen that under the premise of ensuring that the downhole toolface can change, every increase in the rotation angle of the wellhead drill string will result in the same increase in the value of the downhole toolface after reaching a stable state, which is equal to the increased rotation angle of the wellhead drill string.