用两个不同源距的声波测井全波波形计算纵波和横波波速

The calculation of P- and S-wave velocities from acoustic waveform logs with only two receivers in different ranges

1. 清华大学物理系,北京100083;2. 大港油田集团测井公司,天津300451

1. Dept. of Physics, Tsinghua University, Beijing 100083, China;2. Logging Company of Dagang Oil Field, Tianjin 300451, China

讨论两个不同源距的声波测井全波波形的处理问题。用数值模型模拟SKC-B国产大数控声波全波列测井仪后,通过波形的二维谱发现:测井波形中,纵波具有频率选择性,但传播速度不随频率改变,其幅度比较小;横波及伪瑞利波是连在一起的,伪瑞利波的幅度比较大,速度随频率改变。从这些结果可知:用实际测井波形计算纵波时差时,波形中的干扰对计算结果的影响比较大;用实际测井波形计算横波时差时,伪瑞利波对计算结果的影响比较大。

Sonic logging tool SKC-B is simulated with a numerical model in this paper and its two-dimensional spectra of full-waves is used to analyze the frequency characteristics of longitudinal, shear, and Rayleigh waves. Numerical results show that P-wave movemout is affected by the noises contained in the sonic waveform and S-wave movemout is impaired by pseudo-Rayleigh waves. Based on these results, calculation methods of P- and S-wave velocities are constructed.