摘要
本文、首先,提出了一种基于显式有限差分正演的三维瞬变电磁反演方法。对于正演,先计算磁偶极子源激发的全空间初始场,然后使用改进的DuFort-Frankel方法和交错网格对麦克斯韦方程组进行时间步进。对于反演,采用基于L2范数的模型正则化方法和最小二乘最优化方法。其次,通过模型算例和现场实例对三维反演方法进行了测试。在模型算例中,低阻三维块体得到了较好的恢复。在现场实例中,三维反演结果与实际地质情况一致。模型算例和现场实例都表明,提出的基于显式有限差分正演的三维瞬变电磁反演方法是可靠的。
We propose a 3-D transient electromagnetic inversion method based on explicit finite-difference forward modeling.For forward modeling,we calculate the whole-space initial field excited by magnetic dipole sources at an initial time after the current is switched off and apply Maxwell’s equations on time using the modified DuFort-Frankel method and staggered grids.For inversion,we use the least squares optimization method.We test the inversion method using synthetic and field data.The conductivity brick is recovered well in synthetic.The inversion results of field data are consistent with the known geological conditions.The synthetic and field examples show that the inversion method based on explicit finite-difference forward modeling is effective.
作者
李飞
谭强
温来福
黄丹
Li Fei;Tan Qiang;Wen Lai-Fu;Huang Dan(China Earthquake Networks Center,Beijing 100045,China;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing,100085,China;不详)
基金
supported by the Natural Science Foundation of China(Grant no.41974088)
Natural Science Foundation of Hebei Province of China(Grant No.D2023508001).
关键词
三维反演
瞬变电磁法
数值模拟
反演理论
显式方法
3-D inversion
transient electromagnetic method
numerical modeling
inverse theory
explicit method
