中文摘要：

超声泄漏兰姆波对多层介质缺陷及胶结缺失十分敏感,针对其在水泥胶结评价测井中的适用性问题,本文首次利用有限差分法数值模拟探讨了泄漏弯曲波在套管存在腐蚀缺陷和水泥-地层界面不规则起伏时的响应。结果表明,将超声倾斜定向入射时,可有效激发弯曲波模式。套管存在腐蚀时会影响首至弯曲波波幅,首至弯曲波波幅会随套管外壁的缺陷厚度的增加而逐渐减小,并在缺陷长度与波长尺寸相当时达到最弱,缺陷的存在增加了散射,导致直接泄漏回井内流体的首至弯曲波能量减弱。水泥-地层界面的不规则起伏时,首至弯曲波不变,后续弯曲波波幅由于不规则界面散射而减弱。

英文摘要：

Ultrasonic leaky Lamb waves are sensitive to defects and debonding in multilayer media. In this study, we use the finite-difference method to simulate the response of flexural waves in the presence of defects owing to casing corrosion and rough fluctuations at the cement-formation interface. The ultrasonic obliquely incidence could effectively stimulate the flexural waves. The defects owing to casing corrosion change the amplitude of the early- arrival flexural wave, which gradually decrease with increasing defect thickness on the exterior walls and is the lowest when the defect length and wavelength were comparable. The scattering at the defects decreases the energy of flexural waves in the casing that leaks directly to fluids. For rough cement-formation interface, the early-arrival flexural waves do not change, whereas the late-arrival flexural waves have reduced amplitude owing to the scattering at rough interface.