Research on the Design of External Stabilizers for Rotary Steerable Drilling Systems

The rotary steerable drilling system (RSD system) is a widely applied directional drilling technology system at present. The external stabilizer for drill collars serves as a critical mechanical component, which primarily acts as the fulcrum for the turning movement of rotary steerable instruments. Based on the principle of determining a circle with three points, it facilitates the bending of high-rigidity drill collars to achieve the goal of directional drilling. Located in the external flow channel, the external stabilizer’s rib design exerts a significant impact on the fluid behavior within the entire drilling system. Addressing the functional requirements of the external stabilizer, this paper designs a specific structure for the external stabilizer and employs computational fluid dynamics (CFD) methods to conduct three-dimensional numerical simulations. These simulations analyze the flow field characteristics of the fluid passing through the stabilizer ribs, calculate the fluid pressure loss across the external stabilizer, and structural improvements to the ribs are implemented based on the simulation results. The research findings indicate that the fluid streamline becomes turbulent when flowing through the stabilizer ribs, accompanied by a certain degree of pressure loss. Separation vortices are generated under high displacement conditions, and the pressure loss increases proportionally with the rise in displacement. Considering the operational environment of the external stabilizer, an optimized rib structure is determined through algorithm-based parameter selection, which completes the optimal design and ultimately the development of the external stabilize.