Mechanical Performance Analysis of High Pressure Wellhead Based on Thermodynamic Coupling Model

Due to the effect of harsh environmental factors and huge alternating moment loads, subsea wellhead system is prone to fatigue damage. The high pressure wellhead, as an important component and pressure-bearing part of the subsea wellhead, imposes higher requirements on its safety performance under the complex temperature-pressure coupling environment. A comprehensive assessment of the safety performance of key pressure-bearing components in subsea wellhead is crucial, but thermodynamic coupling factors are missing in performance analysis of traditional methods. This paper proposes a safety performance analysis method of the high pressure wellhead, which combines wellbore temperature distribution and location. A coupled finite element model is established for high pressure wellhead thermodynamically analysis, considering the effects of sensitive factors such as bending moment loads and temperature on safety performance. The approach is tested through the application to a case study with a subsea wellhead system in the South China Sea. The results show that the bending moment can cause greater equivalent stress on the pressure bearing components, and the impact on the locking ring is greater than the high-pressure wellhead. Temperature has a particularly significant impact on the casing and locking ring. Compared to traditional subsea wellhead safety performance evaluation methods, the technique proposed can be used for a broader and more comprehensive evaluation of subsea wellhead safety performance, and is more suitable for guidance of practical engineering applications.

Keywords: Subsea wellhead, Moment load, Temperature, Thermodynamic coupling analysis.

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