低速带校正的一种途径──SH波浅层折射勘探

An approach to the correction of low velocity zones: SH-wave shallow refraction survey

由于横波速度较纵波速度低，在近地表差异更大，因此低速带静校正一直是处理横波（转换波）资料的一个难题。要做好低速带校正，首先要求取低速带的速度和厚度。为此在联合采集纵横波资料前，我们在工区做了SH波浅层折射勘探。利用SH波折射资料可以求出低速带速度和厚度。通过对转换波资料的处理可以起到两个方面的作用：使信号归位，有利于纵波及转换波资料对比；使相位的连续性更好。

The static correction for low velocity zones is still regarded as a tough problem in processing shear-wave data bccause the velocity of shear wave is lower than that of compressional wave and the velocity difference becomes larger near the surface. The key to statics is to know the velocity and thickness of the low velocity zone. For this reason, shallow refraction survey with SH waves has been conducted prior to the combined acquisition of the compressional and shear waves and the velocity and thickness of the low velocity zone are obtained from the SH-wave refraction data.The converted-wave data arc useful in two aspects: (1) making the signal image correctly, which is favourable to thc correlation of data between the compressional wave and the converted wave and (2) making the continuity of cvents better.