20DX-10与DSU3地震记录频谱和信噪比特征分析--以沁水煤田中部煤层气地震勘探区为例

Spectrum Analysis and SNR Characteristics of 20DX-10 and DSU3 Records:Taking the CBM Seismic Exploration Area in the Middle of Qinshui Coalfield as Example

在沁水煤田中部煤层气地震勘探区进行实验,采用同一炮同一观测系统同时记录,对模拟检波器20DX-10和数字检波器DSU3的地震记录进行频谱分析和信噪比估算,并进行对比。频谱分析表明:20DX-10的信号频带窄,面波能量远高于DSU3,且衰减相对缓慢;DSU3频带相对更宽,背景噪声、面波等干扰更弱,衰减相对更快,高频信息记录更优。频率域信噪比估算表明,总体上DSU3信噪比更占优势,尤其是高频信息,而20DX-10只在部分时窗低频段才具有信噪比优势。时窗和通带变化时,两种检波器的反射波主频和信噪比随时窗沿水平方向变化,其中时窗的改变一定程度上反映介质差异。

Experiment was conducted in coalbed methane prospecting era,Qinshui Coalfield,and the experiment data of analog 20DX-10 and digital DSU3 sensors recorded by the same observation system with one shot were selected to study the frequency components and the signal to noise ratio.By spectrum analysis,it is shown that 20DX-10 record is of narrow frequency band,higher surface wave energy,and lower attenuation.By contrast,DSU3 record has broader band,less intense surface wave and regular interference.By studying the SNR of the two kinds of record,it is found that the SNR of DSU3 record is higher normally,especially in high frequency domain,while 20DX-10 records SNR is only higher in some no particular time windows or low frequency domain.The changes of time window and pass band lead to the changes of main frequency and SNR,while the change of time window in station direction reflects the change of reflection condition.