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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。
Ultrasound leakage Lamb wave is very sensitive to multi-layer media defects and cementation loss. According to its applicability in cement cementation evaluation logging, this paper for the first time uses the finite difference method numerical simulation to study the existence of leakage bending waves in casing corrosion defects and Response of cement - formation interface irregular fluctuation. The results show that the bending wave mode can be effectively excited when the ultrasonic tilt is directionally injected. The existence of casing corrosion will affect the first to the bending wave amplitude, the amplitude of the first to the bending wave will decrease with the increase of the defect thickness of the outer wall of the casing, and will be the weakest when the defect length and the wavelength are the same, and the existence of the defects will increase Scattering results in a weaker energy of the first bending wave that directly leaks back into the well. In the irregular fluctuation of cement-formation interface, the first to the bending wave is invariable and the amplitude of the following bending wave is weakened due to the irregular scattering at the interface.