Simulation of the Telluric Electrical Field Frequency Selection Method and Its Application in Mineral Water Exploration

In practical engineering geophysics, anomalous bodies are typically three-dimensional (3-D) structures, making it inaccurate to represent the subsurface geoelectric model using a two-dimensional (2-D) assumption. Furthermore, the underlying mechanism of the telluric electrical field frequency selection method (TEFSM) remains insufficiently understood. To address these limitations, this study presents a 3-D forward modeling algorithm based on the edge-based finite element method to solve the TEFSM forward problem. This paper also investigates the application of TEFSM in mineral water exploration, striving to minimize the influence of strong electromagnetic interference sources such as high-voltage power lines. Specifically, the paper presents the forward theory of TEFSM and analyzes the causes of galvanic distortion, particularly static shift. Numerical simulations examine the response characteristics of anomalous bodies and the influence of galvanic distortion. The results indicate that galvanic distortion enhances shallow local anomalies in the modulus of the electric field while masking deeper targets. In contrast, the phase of the electric field effectively reflects deeper anomalous bodies and is minimally affected by galvanic distortion. Future improvements in frequency selectors may enable reliable phase measurements, thereby enhancing data interpretability. Subsequently, the TEFSM was applied to field data collected during mineral water exploration. The field test results confirm the effectiveness of TEFSM and demonstrate that it is a portable, simple, low-cost, and highly efficient method for groundwater detection.