Titanium alloy drill pipes exhibit promising potential for ultra-deep well drilling due to their high specific strength and superior corrosion resistance. However, the engagement surfaces of the pin and box joints feature distinct material stiffness and surface roughness, which influence both the load bearing characteristics and sealing performance. This study establishes a 3D elastoplastic finite element model for steel-titanium heterogeneous drill pipe joints and analyzes their stress distribution under complex loading conditions. Furthermore, a sealing performance evaluation model based on microscopic leakage mechanisms is proposed, and the sealing performance of single shoulder and double shoulder drill pipe joints is comparatively analyzed. The results indicate that, compared to the NC50 single-shoulder joint, the DS50 double-shoulder joint exhibits a 12.8% improvement in sealing performance under an axial tension of 2500 kN, and a 27.6% improvement under combined loading of 2500 kN axial tension and 8 kN·m bending moment. The synergistic action of the primary and secondary shoulders enhances the sealing stability of the drill pipe joint.
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