Drill-String Vibration Analysis Based on Rock Strength Fuzzy Comprehensive Evaluation and Bit–Rock Interaction Parameter Identification

This article proposes an analysis method for coupled axial-torsional drill-string vibration based on fuzzy comprehensive evaluation of rock strength, utilizing identified axial and torsional bit–rock interaction parameters. First, the adaptive particle swarm optimization (PSO) parameter identification method is employed to identify the bit–rock interaction parameters. Then, to improve the accuracy of rock strength evaluation, a fuzzy comprehensive evaluation method of rock strength is proposed based on the identified coupled axial-torsional bit–rock interaction parameters. The effectiveness of the fuzzy comprehensive evaluation method of rock strength is validated by the microrig and field data experiments under different rock samples, and the evaluation accuracy of the proposed method is higher than the linear programming technique for multidimensional analysis of preference (LINMAP) and technique for order preference by similarity to ideal situation (TOPSIS) methods. Finally, according to the on-site bottom hole assembly (BHA) and parameter identification results, the coupled axial-torsional drill-string vibration experiments are carried out and the vibrations are evaluated under different formations. It lays the foundation for developing drill-string vibration suppression strategies under different formations.