%0 Journal Article
%T 套管井中泄漏弯曲型Lamb波声场的模拟与分析</br>Simulation and analysis of leaky flexural-Lamb wavefield in a cased wellbore
%A 陈雪莲
%A 李建赛
%A 唐晓明
%A 李盛清
%A 苏远大
%J 声学技术
%D 2016
%R 10.16300/j.cnki.1000-3630.2016.01.009
%X 基于套管中传播的最低阶泄漏弯曲型Lamb波(以下简称弯曲型Lamb波)对套管后介质尤其是低阻抗慢速水泥声学参数的敏感性,通过建立多层介质模型并利用实轴积分方法,数值模拟了有限尺寸定向辐射探头激发的声场和定点接收的全波波列.结果表明,在声源辐射到套管内壁上的入射角度约为33°时,在套管中主要激发弯曲型Lamb波.声场快照显示弯曲型Lamb波在沿着套管传播时,还会向与套管耦合的泥浆或水泥中泄漏比它速度低的波.若套管后介质是纵横波速度均低于弯曲型Lamb波相速度的慢速水泥,则套管中弯曲型Lamb波的衰减较大.利用弯曲型Lamb波对套管后耦合不同参数介质时的敏感性,可以有效地区分声阻抗接近的固体和液体,提高低阻抗水泥固井质量评价的效果.</br>The lowest order antisymmetric mode of leaky Lamb waves (hereinafter referred to as Lamb flexural mode) has been used for cement evaluation because it is sensitive to the acoustic parameters of media behind the casing (especially the low-impedance and slow cement). With the real-axis numerical integration method and a multi-layered media model, this paper simulates the full waveforms launched and received by directional transmitting and receiving transducers of finite sizes as well as the leaky flexural-Lamb wave field in a cased wellbore. The results suggest that the Lamb flexural mode is mainly excited in casing, when the angle of incidence approximately equals 33 degree. Simulated time snapshots present that the Lamb flexural mode propagates inside the steel casing while leaking bulk waves, whose velocities are lower than the flexural mode's velocity, in the upper water layer and inside the water or cement annulus below the casing. For the slow cement, whose compressional velocity and shear velocity are both lower than that of flexural mode, existing behind the casing, the attenuation is significantly large. By taking advantage of the characteristics of Lamb flexural mode mentioned above, it would be much easy and effective to distinguish solid and fluid with similar impedance, and the effect of evaluating cementation quality of the low-impedance cement could be improved.
%K 泄漏弯曲型Lamb波 定向辐射 慢速水泥 声场快照&lt
%K /br&gt
%K leaky flexural-Lamb waves directional radiation slow cement time snapshots of field
%U http://sxjs.cnjournals.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20160109&journal_id=sxjs