孔隙地层井壁上的声波首波及其诱导电磁场的原因  

Acoustic head wave on the borehole wall in a porous formation and the causes for its accompanying electromagnetic field

作　　者：胡恒山[1] 

机构地区：[1]哈尔滨工业大学航天学院,哈尔滨150001

出　　处：《物理学报》2003年第8期1954-1959,共6页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :10 2 72 0 3 8);哈尔滨工业大学跨学科交叉性研究基金 (批准号 :HIT .MD2 0 0 2 0 4)资助的课题~~

摘　　要：声波测井时孔隙地层中的声波首波平行于井轴沿井壁传播 ,它既有轴向位移分量 ,又有垂直于井壁的位移分量 .这种以快纵波速度传播的波 ,不仅含有由快、慢纵波势给出的梯度场 ,而且还含有由横波势给出的旋度场 .慢纵波势的梯度是渗流位移首波的主要构成成分 ,也是声电效应测井响应中存在伴随声波首波电场的主要原因 .首波包含有旋度位移场 ,是存在伴随声波首波磁场的原因.To understand the propagation mechanism of the acoustic head wave and its accompanying electromagnetic field during logging in a porous formation, we studied the displacement characteristics of the wave. Calculations by both the fast compressional branch-cut-integral and the real-wavenumber-integral methods show that the head wave travels along the borehole wall with the fast compressional wave velocity, but it differs from a plane compressional wave in two aspects. First, the head wave causes radial displacement as well as axial displacement. Second, it is composed of the gradients of the fast and slow compressional potentials and the rotation of the shear potential. The gradient of the slow compressional potential constitutes the dominating part of the fluid filtration. It is the slow compressional potential that induces electric field that accompanies the acoustic head wave during acousto-electric well logging. And it is the shear potential that induces magnetic field that accompanies the acoustic head wave.

关 键 词：声波测井 孔隙地层 声波首波 诱导电磁场 井壁 孔隙介质声学理论 原因 

分 类 号：P631[天文地球—地质矿产勘探]