Characteristic research on electromagnetic response of two-dimensional complex structure targets based on meshless method

Actual geological targets exhibit complex structures and fine grids can improve the modeling accuracy. However, the generation of fine grids is usually difficult. Moreover, the traditional apparent resistivity method can only obtain the approximate range of the target, and cannot accurately distinguish complex structures, including surface and interior complex structures. To address the above problems, this paper proposed to use the meshless method to model complex structure targets. Two-dimensional (2D) numerical simulation of the electromagnetic (EM) response was performed in the frequency domain. The average relative error was 2.88% compared to the analytical solution. Furthermore, an analysis method of relative difference in the apparent resistivity (D a ) was proposed, and the D a between irregular target and regular target was calculated. Two kinds of irregular targets were designed, one was a complex surface target with concave or convex semicircles embedded on the surface, the other was a complex interior target with high and low resistivity anomalies embedded inside. The calculation and analysis results show that the D a method can characterize the electrical difference caused by structure change compared with the traditional method. Our proposed method can facilitate the accurate detection of the surface and interior structure in the target and promote the development of EM methods in the field of complex geological resource detection.