探地雷达衰减补偿逆时偏移成像方法

Attenuation compensated reverse time migration method of ground penetrating radar signals

探地雷达信号在地下介质中传播时易受到电导率所产生的衰减影响,从而使得传统偏移成像结果在高衰减区域变得模糊.本文提出了衰减补偿的逆时偏移方法来消除电导率的影响.该方法基于麦克斯韦方程组实现电磁波的正演模拟和逆时传播.通过改变衰减项的正负号,保证了逆时传播的时间对称性,从而能够重构出原始波场,实现衰减补偿.数值实验比较了传统逆时偏移方法和衰减补偿逆时偏移方法在存在高导异常区域情况下的成像效果,结果证明了衰减补偿逆时偏移方法能够很好地恢复由电导率造成的信号衰减,从而提高探地雷达剖面的分辨率.

Conductivity of subsurface media causes attenuation of ground penetrating radar（GPR）signals,so that the imaging results of conventional migration methods are blurred at strong attenuation zones. We proposed an attenuation compensated reverse time migration method for GPR signals.The forward and time-reverse propagation of electromagnetic waves was based on the Maxwell′s equations.The sign of the conductive term was reversed to keep equations′temporal symmetry,so that the original wavefield could be reconstructed and the attenuation effect was compensated.The numerical experiments further compared the results of conventional reverse time migration and attenuation compensated reverse time migration.The imaging results showed that attenuation compensated method recovered the weak signals within and beneath high conductivity zones and improved the resolution of GPR profiles.