基于Timoshenko梁理论的深水油气井套管柱地震响应分析

Seismic response of casing string of an oil and gas well in deepwater based on Timoshenko beam theory

鉴于海洋表层软土对深水油气井套管柱井身结构稳定性的重要影响,尤其地震发生时,在软硬土层交界面处管柱截面会产生较大弯矩与剪力,据桩基动力响应理论,引入回传射线矩阵法,建立适于深水油气井套管柱的地震响应分析模型。将组合套管柱等效为变截面Timoshenko梁,分别从表层软土剪切波速及厚度分析,探讨套管柱在软硬土层交界面处弯矩与剪力幅值的变化规律,为海洋工程中套管柱的施工、设计及安全性评估提供一定参考及指导。

The soft surface layer has great influence on the stability of a subsea casing string of an oil and gas well in deepwater. Especially, earthquakes can cause a great bending moment and large shear force in cross sections of the casing string. An analysis model for the seismic response of the subsea casing string was established on the basis of pile foundation theories and the method of reverberation-ray matrix. The casing string was asummed to be a Timoshenko beam of variable cross sections. The bending moments and shear forces of the casing string at the interface between soft soil layer and hard one were discussed from the aspects of the shear velocity and thickness of the soft surface layer. The results provided a reference and guidance for construction, design and safety assessment of casing strings in naval engineering.