Abstract: This study investigates the impact of different power supply direction excitation on the exploration effect of the three-dimensional (3D) induced polarization (IP) method, for a central gradient array of  multi-group power supply pole distance combinations. We employ the 3D unstructured finite element numerical simulation for direct current  point power supply and the incomplete Gauss-Newton 3D inversion. The goal is to provide a basis for the rational selection of power supply directions for 3D IP measurements. First, we design various 3D geoelectric models and conduct forward and inverse modeling for three power supply modes: transverse, longitudinal, and transverse/longitudinal bidirectional combinations. Then we perform 3D inversion on IP measured data obtained in a mining area under these three power supply modes. Finally, the 3D inversion results of theoretical model synthesis data and measured data and the existing geological data of the mining area are synthetically analyzed. We find that 3D inversion results for IP data under transverse, longitudinal, and transverse/longitudinal bidirectional combination power supply modes can effectively depict the lithological and structural distribution characteristics. In terms of revealing local anomaly information, the bidirectional combined power supply IP data yields the most abundant and complete information. By contrast, the inversion results of single-directional power supply IP data may lack some effective anomaly information, presenting incomplete anomaly details.

Key words: IP, central gradient array, 3D, power supply direction, inversion