深水测试管柱应力分布规律与动态响应分析

为了研究深水测试管柱在不同工况下的应力分布规律及内压波动对管柱动态响应参数的影响,根据深水测试管柱作业特点及结构,推导了测试管柱的轴向力、轴向应力、径向应力和环向应力计算公式,建立了海水段测试管柱的横向及纵向振动模型。根据不同工况,建立了测试管柱的有限元模型,进行了测试管柱最大应力及内压波动下的动力响应分析。研究结果表明:测试管柱各段的最大应力随水深的增加而减小、随悬挂力的增大而增大;由于泊松耦合的影响,最大应力与水深的变化率随着内外压差的增大而增大;初开井前,由于测试管柱的内加压和环空泄压,测试管柱出现最大应力,其值为255.7 MPa,但各工况下测试管柱的安全系数满足强度使用要求;内部压力波动周期对测试管柱的应力响应影响显著,低周期的内压波动使管柱应力过度增大,管柱易发生危险。研究结果可为深水测试管柱的强度研究提供一定的指导。

Analysis of Stress Distribution Law and Dynamic Response of Deep Water Test String

To study the stress distribution and the influence of internal pressure fluctuations on the dynamic response parameters of deep water test string under different working conditions,the calculation formulas of the axial force,axial stress,radial stress and hoop stress are derived based on the characteristics of the deepwater testing operation and the composition of the test string.The lateral and longitudinal vibration models of the test string above the mud line are established.According to different working conditions,a finite element model of the test string is established,and the dynamic response analysis of the test string under maximum stress and internal pressure fluctuations is conducted.The study results show that the maximum stress of each section of the test string decreases with water depth and increases with the suspension force.Due to the influence of poisson coupling,the change rate of maximum stress with water depth increases with the internal and external pressure difference.Before the initial well opening,the test string’s maximum stress of 255.7 MPa is observed due to the internal pressure of the test string and the pressure relief in the annulus,but the safety factor of the test string under different working conditions meets the strength requirements.The internal pressure fluctuation period has a significant impact on the stress response of the test string.Low-period internal pressure fluctuations could cause excessive stress increase of the test string,making the test string prone to hazard.The study results can provide guidance for the strength study of deep water test strings.