Real-Time Control Algorithm of Well Trajectory for Push-the-Bit Rotary Steering Drilling System

Abstract

Summary A “push-the-bit” rotary steering system (RSS) is one kind of advanced steering technology widely used in the drilling of extended-reach wells and horizontal wells. However, some problems, including instability of buildup rate and large deviation of well trajectory, still occur frequently in directional drilling with push-the-bit RSS due to the drillability anisotropy of formation rock, external disturbance, and so on, especially under complex operating conditions. In this paper, we build a compound control algorithm for well trajectory of push-the-bit RSS to solve this problem. The compound control algorithm includes two novel control modules—slight hole deviation control and severe hole deviation control. The slight hole deviation control can improve the smoothness of well trajectory, and the severe hole deviation control can ensure high control accuracy. The comprehensive performances of the compound control algorithm are compared with other control algorithms, including severe hole deviation control, slight hole deviation control, and intelligent switch control, in terms of trajectory smoothness, trajectory control accuracy, control smoothness of pushing force, and computational efficiency. The results indicate that the compound control algorithm is the best. This algorithm is also applicable for trajectory correction in cases of severe hole deviation and azimuth drift on different well sections.