Evaluation of the Capabilities of Grounded-Wire Source Surface-Borehole Transient Electromagnetic Detection in Complex Geological Settings

The surface-borehole transient electromagnetic method exhibits significant advantages in identifying deep targets, as its closer distance to subsurface targets results in more pronounced effective anomalies when compared to surface-based techniques. The grounded-wire source TEM demonstrates enhanced capabilities for deep exploration, featuring increased penetration depth, enhanced signal response, superior resolution, and minimized volume effects, which render it especially effective for examining intricate deep reservoirs. This study utilizes a time-domain finite-element method with unstructured tetrahedral grids to conduct three-dimensional numerical simulations of grounded-wire source SBTEM in complex terrains, capitalizing on the flexibility and precision of this method for modeling detailed geological structures. A comparative analysis of electromagnetic field responses between conductive and high-resistivity targets indicates that the detection capability of magnetic field components decreases more markedly than that of the vertical electric field Ez as the burial depth of the target increases. The grounded-wire source SBTEM exhibits enhanced sensitivity and better identification capabilities for conductive targets when compared to high-resistivity alternatives. The present research represents a detailed analysis of the impact of complex terrain on the detection capabilities of grounded-wire source SBTEM, utilizing electromagnetic response simulations of typical three-dimensional complex geological models. The results provide robust theoretical backing and empirical evidence for an enhanced understanding of subsurface resource exploration.