地层吸收衰减与地震仪器记录性能

要想分辨埋深1500m以下厚度达到或接近1m的地层，要求地震仪器应能记录1000Hz以上的高频信号，瞬时动态范围应达到或接近120dB。无论是早期的集中式数字地震仪还是当代24位遥测地震仪，均还远未达到这一技术要求。从均匀介质出发，选择主频150Hz的Ricker子波，计算了地震波在地层传播过程中的能量衰减和频率吸收情况，并在此基础上分析计算了地震仪器的瞬时动态范围和所能记录的信号最高频率。针对时间t0大于1．5S的地震反射。计算结果表明其瞬时动态范围在60dB左右，所能记录的信号最高频率不超过170Hz。

Absorption and attenuation of stratum and recording performance of seismic instrument

To distinguish strata with thickness of about 1 m under depth of 1 500 m,a seismic instrument must have the ability to record signals whose frequencies are more than 1 000 Hz. And its instantaneous dynamic range should reach up to about 120 dB. Either the early centralized digital seismograph or the modern 24-bit telemetric seismograph cannot meet this demand. Based on even medium and using Ricker wavelet with dominant frequency of 150 Hz, this paper calculated theoretically the attenuated energy and absorbed frequency during propagation of seismic waves. The instantaneous dynamic range and the highest frequency that can be recorded were then analyzed. It is shown that for seismic reflections with traveltime exceeding 1.5 s, their instantaneous dynamic ranges will be about 60 dB, and the highest frequency of signals cannot exceed 170 Hz.