可控源音频大地电磁法多通道观测的电容耦合效应与电容去耦研究

Capacitively coupled effect and capacitive decoupling of multichannel controlled-source audio magnetotellurics observations

可控源音频大地电磁法通常采用多通道模式进行数据采集,而多通道的多条接收导线和接收电极与大地之间经常形成一种电容耦合效应,导致观测的视电阻率和相位曲线出现畸变。本文用等效电路模型对观测模式的电容耦合进行正演模拟,通过几个典型模型的正演模拟,分析了接收导线长度、电极接地电阻对电容耦合效应的影响特征。研究了可控源音频大地电磁法观测装置的电容去耦方法,并应用于辽宁省红透山矿区的实测数据处理,有效地削弱了电容耦合效应,提高了观测质量,反演结果与已知地质信息吻合较好。本文通过试验验证了电容去耦方法的可操作性,为规范可控源音频大地电磁法数据采集技术提供了科学依据。

Controlled-source audio magnetotellurics,which is a common technology in geophysical surveys,typically uses the multichannel mode of data acquisition.Often,a capacitive coupling effect occurs among the multiple receiving wires and receiving electrodes and the earth.This effect causes the distortion of the observed apparent resistivity and phase curves.The capacitive coupling of the observation mode is simulated using an equivalent circuit model,and the characteristics of the influence of the length of the receiving wire and grounding resistance of the electrode on capacitive coupling are investigated via the forward simulation of several typical models.The capacitive decoupling of a device for controlled-source audio geomagnetic observation is studied and applied to process the measured data from the Hongtoushan mining area in Liaoning Province,China.This approach effectively weakens the capacitance coupling effect and improves observation quality,and the inversion results match well with known geological information.This study examines the capacitive decoupling technique and offers a scientific foundation for the standardization of the controlled-source audio geomagnetic data gathering technology.