软地层随钻测井仪器偏心情况下低频四极子源激发波场的数值分析  

Numerical analysis of the low frequency quadrupole acoustic field excited by eccentric quadrupole source with eccentric logging instrument in soft formation

作　　者：闫向宏 朱琳 闫世鹏 方恒忠 杨喜峰 YAN Xianghong;ZHU Lin;YAN Shipeng;FANG Hengzhong;YANG Xifeng(College of Science in China University of Petroleum East China,Qingdao 266580,China;Academic Affair Office in Shengli College China University of Petroleum,Dongying 257061,China)

机构地区：[1]中国石油大学(华东)理学院,青岛266580 [2]中国石油大学胜利学院教务处,东营257061

出　　处：《应用声学》2022年第3期447-452,共6页Journal of Applied Acoustics

基　　金：国家自然科学基金面上项目(11774433)。

摘　　要：为了探索测井仪器偏心对随钻低频四极子波场的影响,利用有限元法(多物理场耦合有限元软件包)对软地层井孔中随钻仪器偏心情况下低频四极子声源激发的波场进行了数值模拟。通过对随钻四极子测井波形的分析可知,当采用低频随钻四极子偏心声源激发时,测井波列中除传播速度与低速地层横波速度相当的地层四极子波模式外,还存在一个幅度非常低、传播速度略高于井孔流体中声速的模式波,该模式被对应钻铤弯曲波模式,且该模式波的幅度随着随钻四极子源偏离井孔中心距离的增大呈二次方规律增大,地层四极子模式波幅度呈三次方规律增加。In order to explore the influence of logging instrument eccentricity on low frequency quadrupole wave field while drilling,numerical calculation on the low frequency quadrupole acoustic field excited by eccentric quadrupole source with eccentric logging instrument in soft formation by using the finite element method is carried out.According to the analysis results for the waveform of the quadrupole logging while drilling,when using low frequency eccentric quadrupole source to excite the quadrupole acoustic field,there are two different wave patterns in the received waveforms.In addition to the quadrupole wave pattern which propagation speed equivalent to the shear wave velocity in soft formation,also there is another kind of wave pattern with a very low amplitude and higher propagation speed than the borehole fluid velocity in front of the quadrupole wave pattern,this wave pattern is called drill collar bend wave pattern,the amplitude of this wave patterns enlarges according to quadratic low with the increase of eccentric distance of quadrupole source and the formation quadrupole wave pattern increase according to cubic rule.

关 键 词：随钻声波测井 随钻四极子 圆形井孔 偏心四极子声源 

分 类 号：O42[理学—声学]