【摘要】 通过建立钻井液、套管和水泥等多层介质模型，理论模拟和实验测量相结合研究弯曲型Lamb波在套后耦合不同速度水泥时的频散、衰减以及全波波形。理论模拟结果发现若测量频段弯曲型Lamb波的相速度与水泥纵波速度相交，弯曲型Lamb波的频散曲线在相交的频率点会出现速度跃变，频散曲线不再连续，且断点前后其衰减值差异大，接收到的直达弯曲型Lamb波也展现出两个紧凑的波包。实验结果也印证了频散曲线不连续的现象，实验测量波形提取的频散曲线与解析计算的频散曲线吻合。此现象为直接从频散曲线断点获取水泥的纵波速度以及区分套后耦合水泥的类型提供了可能。更多还原

【Abstract】 A multilayer medium model, incorporating drilling fluid, casing and cement, was established to study the response characteristics of flexural Lamb wave logging through theoretical calculations and experimental measurements. The theoretical simulations reveal that the dispersion curve of the flexural Lamb wave splits into two branches: a low-frequency branch and a high-frequency branch when the cement P-wave velocity intersects the dispersion curves of flexural wave within the logging frequency band. The direct flexural Lamb wave received also shows two compact wave packets. Experimental results further confirm this discontinuity in the dispersion curve, with the experimentally extracted curve aligning closely with analytical calculations. This phenomenon allows for direct determination of the cement’s P-wave velocity from the breakpoint of the dispersion curve, facilitating the identification of post-coupling cement types.更多还原