Force analysis and optimization of rotary steerable bottom hole assemblies in slide drilling

Abstract:

To address drag resistance and inclination control issues during slide drilling with traditional “single-bend single-stabilizer” bottom hole assemblies （BHAs） in horizontal wells， improving drilling efficiency and downhole safety， this study innovatively proposes a rotating stabilizer BHA. Based on previous field trial results and data， a mechanical model of the bottom hole assembly was established using longitudinal and transverse beam bending theory， focusing on calculating drill bit lateral force and stabilizer friction resistance. Simulations analyzed changes in mechanical performance under varying structural parameters， wellbore parameters， and drilling parameters. The results indicate that： Changes in the positive displacement motor bending angle have no significant effect on drill bit lateral force or stabilizer friction resistance. Considering practical conditions， using motors with excessively large bending angles is not recommended to minimize drilling tool wear caused by the wellbore wall； The outer diameter of the stabilizer and the distance from the drill bit to the stabilizer significantly influence drill bit lateral force and friction. When optimizing structural parameters， these stabilizer attributes can be primarily adjusted in conjunction with wellbore parameter conditions to meet different inclination requirements； To enhance drilling efficiency and downhole safety， it is recommended to employ this assembly with a stabilizer outer diameter range of 0.214 to 0.215 meters， a bending angle range of 1.5 to 2.5 degrees， a distance from the stabilizer to the drill bit of 0.4 to 1 meter， and a distance from the bending point to the stabilizer ranging from 1.4 to 1.8 meters. These findings can guide the optimization design of the rotating straightening bottom hole assembly’s structural parameters， support its field application， improve inclination control during sliding drilling in deviated sections， reduce pressure support risks， and possess practical engineering significance.