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Abstract The drilling environment and tool assembly in deep and ultra deep wells are more complex, leading to increased vibration loads underground, which can cause fatigue crack propagation and failure of drill pipe joints, leading to early scrapping of drill pipes. In response to the above issues, this article conducts the following research: establishing a dynamic calculation model for drill pipe joints, analyzing the axial force, torque, and bending moment loads borne by drill pipe joints underground; Conduct a finite element analysis model of the drill pipe joint to determine whether the stress on the drill pipe joint meets the material strength requirements; Establish a crack propagation model for drill pipe joints and analyze the remaining life of the joints. Conclusion: By comparing with indoor experiments, it has been proven that the established dynamic calculation model is effective. It is found that in the target environment, the drill pipe joint is subjected to three loads: 13.11kN axial force, 35 torque (including make-up torque), and 0.75 bending moment; Through composite load analysis, the maximum Mises stress borne by the male and female joints is 551.2MPa and 323.2MPa, which meets the material strength requirements; The thread extension of drill pipe joints is mainly characterized by open type cracks, and their depth has a greater impact on crack propagation than their length; Under current operating conditions, the minimum crack propagation size is 3x2mm, and the remaining life at this size is 126820 times.
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Received: 25 November 2024
Published: 26 June 2025
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2025, Vol. 46 
