偶极随钻声波测井声压和径向位移响应的差异  

Difference in pressure and radial displacement response of dipole acoustic logging while drilling

作　　者：陈达 张超 关威[1] 胡恒山[1] CHEN Da;ZHANG Chao;GUAN Wei;HU Hengshan(Department of Astronautics and Mechanics,Harbin Institute of Technology,Harbin 150001,China)

机构地区：[1]哈尔滨工业大学航天科学与力学系

出　　处：《应用声学》2019年第5期801-806,共6页Journal of Applied Acoustics

基　　金：国家科技重大专项子课题项目(2017ZX05019006-006);国家自然科学基金项目(41574112,41874129,11734017)

摘　　要：声波测井仪接收到的电信号通常是多个压电片响应的叠加,它主要是由声压还是径向位移响应转化而来,或是两种响应兼有目前未有定论。该文通过实轴积分法和复变函数法计算并对比分析随钻声波测井的声压和径向位移场,发现这两种响应特性有着显著的差异。首先,软地层的偶极随钻测井时,声压信号包含钻铤波和舒尔特波两个波群,而径向位移信号仅有钻铤波波群;其次,单极声源情况下,声压和径向位移信号的钻铤波能量分别集中在钻铤内、外壁,而偶极情况恰好相反,可见,钻铤按照单极情况的分析结果进行刻槽后,高频时的拖尾现象会影响偶极信号中舒尔特波对横波速度的反演。因此,阐明两类信号的差异对横波速度的反演和钻铤波的压制都具有重要意义。The electrical signal received by acoustic logging instrument is usually the superposition of multiple piezoelectric responses, which is mainly converted from acoustic pressure or radial displacement response, or both responses have not been determined yet. In this paper, the acoustic pressure and radial displacement fields of LWD acoustic logging are calculated and analyzed by means of real axis integral method and complex variable function method. The results show that when in soft formation dipole logging while drilling the acoustic pressure signal consists of two wave groups, drill collar wave and Scholte wave, while the displacement signal consists of only collar wave group without apparent Scholte wave. On the other hand, in the case of monopole sound source, the drill collar wave energy of pressure and radial displacement signals is concentrated in the drill collar and the outer wall respectively, while in the case of dipole, it is just the opposite. Besides, when grooving according to the results of the monopole case, the phenomenon of tail dragging at high frequency will affect the inversion of shear wave by Scholte wave in the dipole source. So it is of great significance to clarify the properties of the two kinds of signals for shear wave inversion and drill collar wave suppression.

关 键 词：随钻声波测井 钻铤波 声压 径向位移 软地层 

分 类 号：P631.413[天文地球—地质矿产勘探]