3D Forward and Inversion Problems of Borehole-to-Surface Electrical Method

After simplifying the borehole-to-surface electrical problem as a model with a vertical line source, the authors achieved 3D resistivity forward modeling of a vertical line source of electrical current using finite element method (FEM). The authors also achieved 3D resistivity inversion on the basis of iterative nonlinear damped least square method. Some simplified models were adopted to test both the forward and the inversion algorithms. The authors used "synthetic data" obtained from the forward modeling to inverse the target resistivity in the model. The authors also investigated the possible effects of data surveying region and noises on the inversion quality of target resistivity. This study would provide some theoretical background for enhancing the quality of inversion problem of borehole-to-surface electrical method.