摘要
为了实现套管内无流体介质时的固井质量检测,可以利用电磁超声技术在套管中激发沿周向传播的准Lamb波,根据其衰减特征评价套管与水泥之间界面的胶结质量.本文通过理论和数值仿真两种方法研究了周向传播的准弯曲型Lamb波的频散和衰减特征,并将计算结果与轴向传播的弯曲型Lamb波进行了对比.计算结果表明,当套管外耦合流体时,周向传播的准弯曲型Lamb波的相速度略低于轴向传播的弯曲型Lamb波,但周向传播的衰减明显较大;波结构图显示两种传播方向的弯曲型Lamb波在套管内传播时均以径向位移为主,轴向传播时内外壁的振动位移幅度基本一致,而周向传播时外壁的振动位移幅度高于内壁,会使得向套管外泄漏的能量较多.当套管外耦合轻质水泥时,轴向传播的弯曲型Lamb波的频散曲线在水泥纵波速度位置处存在断点,而周向传播的准弯曲型Lamb波的频散曲线不存在断点.此外随着水泥声阻抗的增加,轴向传播与周向传播的弯曲型Lamb波的衰减均先增加再减小,但周向传播的准弯曲型Lamb波的衰减明显较高,衰减取最大值时对应的水泥阻抗也明显高于轴向传播的弯曲型Lamb波.通过有限元仿真软件模拟了沿套管周向和轴向传播的弯曲型Lamb波的声场快照,并通过阵列波形提取了其衰减随激发主频的变化规律,数值仿真和理论计算结果吻合,为进一步利用周向传播的准弯曲型Lamb波开展固井质量评价奠定了理论基础.
To evaluate cementing quality in the absence of a liquid medium inside the casing,Electromagnetic Acoustic Transducers(EMATs)can be employed to generate quasi-Lamb waves that propagate circumferentially along the casing.The attenuation characteristics of these waves can be analyzed to assess the bonding quality at the casing-cement interface.This paper investigates the dispersion and attenuation characteristics of quasi-flexural Lamb waves propagating circumferentially through both theoretical and numerical simulation methods,comparing the results with those of flexural Lamb waves propagating axially.The findings indicate that when the casing is coupled with fluid,the phase velocity of the quasi-flexural Lamb wave propagating circumferentially is slightly lower than that of the flexural Lamb wave propagating axially,but its attenuation is significantly higher.In terms of wave structure,the primary displacement during propagation along the casing is radial in both cases.While the displacement distribution between the inner and outer walls is uniform during axial propagation,the displacement amplitude of the outer wall is higher than that of the inner wall during circumferential propagation,resulting in energy leaking outward.When the casing is coupled with lightweight cement,the dispersion curve of the flexural Lamb waves propagating axially exhibits discontinuities,whereas the dispersion curve of the quasiflexural Lamb wave propagating circumferentially remains continuous.Additionally,as the cement acoustic impedance increases,the attenuation of both axially and circumferentially propagating flexural Lamb waves initially rises and then declines.However,the attenuation of the quasi-flexural Lamb wave propagating circumferentially is significantly higher,and the cement impedance corresponding to the maximum attenuation is notably higher for the circumferentially propagating quasi-flexural Lamb wave compared to the axially propagating flexural Lamb waves.Using finite element simulation software,the well logging responses of the quasi-flexural Lamb wave propagating circumferentially and axially along the casing were simulated.The extracted attenuation values are consistent with the theoretical calculations.The study lays a theoretical foundation for further research on cementing quality evaluation using quasi-flexural Lamb wave that propagates circumferentially along the casing.
作者
潘金林
陈雪莲
苏远大
唐晓明
PAN JinLin;CHEN XueLian;SU YuanDa;TANG XiaoMing(School of Geosciences,China University of Petroleum(East China),Qingdao Shandong 266580,China;National Key Laboratory of deep Oil and Gas,China University of Petroleum(East China),Qingdao Shandong 266580,China)
出处
《地球物理学报》
北大核心
2026年第1期426-436,共11页
Chinese Journal of Geophysics
基金
国家自然科学基金(42374156,41774141)
崂山国家实验室项目(LSKJ202203400)联合资助。
关键词
套管井
弯曲型Lamb波
周向传播
衰减曲线
频散曲线
Casing well
Quasi-flexural Lamb wave
Circumferential propagation
Attenuation curve
Dispersion curve
