Abstract:The dynamic response of oil well casings during earthquakes is crucial for the safety of oil well production and operation. In this work, a mechanical model for the transverse vibration of oil well casings was established based on the theory of elastic foundation beam and soil-structure interaction. Moreover, the numerical models for site soils without oil well casing and oil well casing-soil were established using the finite element and time-history analysis methods. The dynamic response characteristics of oil well casings subjected to El-Centro waves with varying peak accelerations were also investigated. The results indicate that, with increased burial depth, the displacement and acceleration responses of the casing and soil decrease, while the reduction amplitude increases. The seismic dynamic response of site soil is decreased due to the casing, while the reduction amplitude is small. The casing's seismic dynamic response is most pronounced at the surface (0 m), highlighting the nonlinear characteristics of soil. The casing produces stress concentration near the surface (0 m), representing the most critical position. The sudden change of stress occurs at the position where the soil stiffness changes considerably, with peak stress values fluctuating continuously in 2-6 and 9-12 s, resulting in severe deformation and damage to the casing. Furthermore, the acceleration time-history curve of the casing lags behind the input seismic wave time-history curve by 0.08 s. Soil deformation near the surface (0 m) is more severe than that in deep soil, and the acceleration time-history curve exhibits distinct multipeak characteristics. The research findings serve as a theoretical foundation and provide technical support for seismic design, safe production, operation, and maintenance of oil wells.
