2D, 3D Forward Modeling And Inversion Research Of Resistivity Tomography Technique

The Resistivity Tomography (RT) technique is an important geophysical tool in exploring the interior of the earth from shallow to deep and widely apply in the hydrology, engineering, environment, archeology, mineral resource survey, oil-gas exploration. At present, the former geophysicists have done massive work in investigation and application for the surface of Resistivity Tomography. Well, the investigation and application of surface to hole and hole to hole Resistivity Tomography technique at present still obviously insufficient. This paper summarized in detail the former geophysicists about the concept of RT technique, research history and investigation production. Based on these, the paper uses finite difference method, finite element method and smooth constrained least square method to develop resistivity forward numerical modeling and inversion research for 2D, 3D surface electrical resistivity survey and 2D, 3D surface to borehole electrical resistivity survey on some typical synthetic model, thus summarized detailedly the characteristic of response apparent electrical resistivity. Not only obtain some innovative cognition, but presenting some significant conclusions as well.Through developing finite difference forward modeling and inversion technique in 2D surface and then according to the characteristic of response apparent electrical resistivity of different configuration arrange in combined horizontal structure and combined vertical structure. Resolution and method characteristic of the commonly used configuration have been analyzed.It is helpful to choice right configuration or combined configuration for special geological task in practice.Through establishing several synthetic models, then uses 3D finite difference method, researching familiar in practice of high and low resistivity coexist of 3D resistivity model's dipole-dipole anomalous characteristic. And analyzed in high and low resistivity coexist situation of the anomalous distributed rule of 3D apparent resistivity.Surface to hole RT technique research is leading content in the paper. Resolution of surface to hole RT technique is much better than surface RT technique for deeper objective, for surface to hole RT technique will place the current electrodes to the hole. But response apparent resistivity of surface to hole configuration relate with electrode array, depth and property of objective, and distance between the objective and the hole. Response apparent resistivity has the inherent complexity, and brings very major difficulty for processing and interpreting the information accurately. By using 2D surface to hole and cross hole finite element forward modeling and inversion on high resistivity horizontal tabulate body, low resistivity horizontal tabulate body, and anticline reservoir model, and by using 3D surface to hole finite element forward modeling and inversion on high resistivity horizontal tabulate body, low resistivity horizontal tabulate body, the response apparent resistivity characteristic are investigated detailedly and obtained important conclusions. It is helpful to process and interpret accurately the information in practice and it is applicable for oil-gas exploration and mineral resource survey.