摘要
目前评价固井质量的声波测井方法均是在井内泥浆中辐射声波,再耦合到套管中激发套管波,这种测量方式在重泥浆或含气的井筒内应用时受到了限制.本文将电磁超声换能器引入到套管井中,无需井内介质的声耦合直接在套管中激发沿着套管轴向偏振、周向传播的准SH波.利用多物理场有限元仿真技术优化设计了磁盘阵列式的偏置磁场和跑道型线圈结构的电磁超声换能器,基于洛伦兹力机理实现了在铁磁材料的套管中激发和接收环向传播的准SH波的电磁超声转换技术.根据优化设计结构在实验室研制了电磁超声换能器,有限元模拟和实验室测量均观测到了沿套管环向传播的零阶及一阶准SH波.有限元模拟结果还显示在胶结良好的套管井中,准SH波一边沿着套管环向传播,一边向水泥环中辐射准SH波;在水泥和地层界面准SH波还会发生反射,再耦合到套管中被接收器接收到,通过对比硬地层和软地层两种套管井模型中接收的反射波信息,可观测到反射的准SH波相位相反,反射波和直达波的相位变化充分验证了准SH波的传播特征.
For acoustic logging methods in a cased well,the conventional working pattern is that the acoustic wave is excited in the mud and radiates into the casing,and then the casing wave is induced.This way is not efficient in heavy-weight or gassy mud.This paper introduces the electromagnetic acoustic transducer(EMAT)based on Lorentz force mechanism into the cased well.The advantages of EMAT are that the quasi-SH waves can be induced in the casing directly without acoustic coupling between mud and casing.The quasi-SH waves are polarized in the axial direction and propagates circumferentially.Combining the COMSOL finite element simulation the Lorentz force type electromagnetic ultrasonic transducers are designed and optimized.Quasi-SH0 and higher modes can be excited in the casing.The electromagnetic ultrasonic transducers based on the simulation results recorded the SH waves propagating circumferentially along the casing in the laboratory.In a well-bonded well,quasi-SH waves propagate along the casing circumferentially and leak energy into the cement behind the casing,and the leak quasi-SH waves can be reflected at the interface between cement and formation.Then the reflected waves can be coupled into the casing and received by the receivers.In hard and soft formation cased well models,the reflected waves are in opposite phases.Comparing with direct waves,the phase changes of reflected waves fully verify the propagation characteristics of quasi-SH waves.
作者
陈雪莲
庄妍
夏飞月
殷晓康
唐晓明
CHEN XueLian;ZHUANG Yan;XIA FeiYue;YIN XiaoKang;TANG XiaoMing(School of Geosciences,China University of petroleum,Qingdao Shandong 266580,China;Key Laboratory of Deep Oil and Gas,China University of petroleum,Qingdao Shandong 266580,China;School of Mechanical and Electronic Engineering,China University of petroleum,Qingdao Shandong 266580,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第4期1519-1527,共9页
Chinese Journal of Geophysics
基金
国家自然科学基金(41774141,41821002)
中石油重大科技项目(ZD2019-183-004)资助.
关键词
电磁超声换能器
洛伦兹力
准SH波
套管井
Electromagnetic acoustic transducer
Lorentz force
Quasi-SH wave
Cased well
