多频激电相对相位谱研究
来源期刊:中南大学学报(自然科学版)2004年第1期
论文作者:陈儒军 何继善 白宜诚 汤井田
文章页码:106 - 111
关键词:伪随机多频信号;激发极化;相对相位谱;耦合感应; Cole-Cole模型
Key words:pseudo-random multi-frequency signals; induced polarization; relative phase spectrum, induc-tive coupling, Cole-Cole mode
摘 要:2n系列伪随机多频信号含有多个在对数坐标上呈等间距分布的主频率,是电法勘探的理想场源。多频激电相对相位谱法采用上述信号作为场源,充分反映了该信号作为电法勘探场源的优点。在多频激电相对相位谱法中,相对相位谱定义为φr(ω)=[kφ(ω)-φ(kω)]/(k-1)。根据傅里叶变换的性质和激电效应与耦合感应的关系,证明相对相位谱测量具有如下优点:可以消除发送机和接收机之间因时间不同步而引起的测量误差,提高了观测精度;对电磁耦合感应进行了一阶线性校正,可以压制耦合感应。通过改变Cole-Cole模型中的频率相关系数c 和频比k来分析相对相位谱与相位谱的差异,发现相对相位谱与相位谱在形态上一致,对异常具有同等的反应能力;它们之间的差值与频比k成反比、与频率相关系数c成正比。野外实测的多频激电相对相位谱和相位谱说明,激电相对相位谱测量对耦合感应具有良好的压制效果。
Abstract: The 2nseries pseudo-random multi-frequency (PRMF) signals have several main frequencies, which are equally spaced on log scale coordinates. It is the ideal excitation source for electrical exploration. In induced polarization method, multi-frequency relative phase spectrum method use above signal as field source, showed the advantage of PRMF signal used as field source for electrical exploration. In multi-frequency relative phase spectrum (RPS) method, RPS is defined as φr(ω)=[kφ(ω)-φ(kω)]/(k-1). Based on property of Fourier transform and relation between induced polarization and electromagnetic coupling, RPS measurement proved the advantages of eliminating measurement error caused by synchronous error between receiver and transmitter, carrying out one order linear correction for inductive coupling, and suppressing inductive coupling. The difference between IP phase spectrum and RPS spectrum is analyzed by changing frequency dependant factorcin Cole-Cole IP mode and frequency ratiok. It is found that PRS has the same shape as phase spectrum, shares the same ability to reflect the anomaly source, the difference between IP phase spectrum and RPS spectrum is direct proportional tocand inverse proportional tok. The multi-frequency RPS and phase spectrum measured in field proves that the IP RPS measurement works well in removing inductive coupling. PRS has the same shape as phase spectrum, shares the same ability to reflect the anomaly source.