FDTD Numerical Simulation and Detection Capability Analysis of Small Loop Transient Electromagnetic Method in Shallow Water

Abstract

The small loop transient electromagnetic method (TEM) in shallow water has strong adaptability and high resolution and is one of the current research hotspots. In this paper, a shallow-water model of a typical low resistance anomaly is established, which can be obtained through numerical simulation analysis. In the early time, the shallow water layer has large response and the low resistivity abnormal body has small response; In the late time, the shallow water layer has small response induction response and the low resistivity anomaly has larger response, and the response curve shows “double peak” attenuation law; The effects of different thicknesses of shallow water layers on the response of low resistivity abnormal bodies show “single peak”, “double peak”, and “peak wave trough” attenuation laws; However, the effect of different resistivity in shallow water layer on the response of the low resistivity abnormal body only shows the attenuation pattern of “single peak” and “peak wave trough”. Finally, the article takes the highway site selection survey as an example, combined with the high density resistivity method comparison analysis, and verifies the reliability and accuracy of the detection results of the small loop TEM in shallow water. The research work provides a theoretical reference for the qualitative analysis of the response characteristics and data processing interpretation of the small loop TEM in shallow waters.