Two-dimensional Regularization Inversion Of Self-potential Of Sandstone-type Uranium Deposits And Its Application

Based on the electrochemical mineralization mechanism of interlayer oxidation zone sandstone-type uranium deposits,the spontaneous potential method has gradually become one of the most promising geophysical prospecting methods for the exploration of interlayer oxidation zone sandstone-type uranium deposits.In the past exploration work of sandstone-type uranium deposits in the interlayer oxidation zone,due to the complexity of the formation mechanism of the spontaneous potential of this type of uranium deposit,the inversion and interpretation of the abnormal data of the spontaneous potential of uranium deposits is not ideal.In order to improve the application effect of the spontaneous potential method,this paper systematically carried out the two-dimensional finite element numerical simulation of the spontaneous potential and the regularization inversion on the basis of clarifying the source of the underground natural electric field in uranium mines.The thesis first discusses the genetic model of sandstone-type uranium deposits in the southern margin of the Yili Basin,and deeply analyzes the spontaneous potential generation mechanism of sandstone-type uranium deposits in the interlayer oxidation zone.In the process of uranium mineralization,the oxidation-reduction reaction converts chemical energy into electrical energy,generating an "oxidation-reduction" electric field.At the same time,because the mineralization geology and hydrogeological conditions are preserved,the oxidants and reducing agents are constantly replenished due to the action of the groundwater replenishment-diameter-exhaust dynamic system,the redox reaction continues,and the oxidation-reduction potential is maintained.On the basis of the oxidation-reduction potential theory derived from the research,the thesis carried out in-depth research on the two-dimensional forward and inversion of natural potential.If the complex physical and chemical process of the formation of the "oxidation-reduction" electric field is not considered,the natural electric field of the sandstone-type uranium deposit in the interlayer oxidation zone can be approximated as a stable current field.In terms of forward modeling,this paper re-derives the potential equations and boundary conditions that the natural current field satisfies based on the theory of stable current fields;through the introduction of unstructured triangular meshes,the two-dimensional natural potential numerical simulation of the finite element method is realized;the two are compared.The analytical solution of this rule model and the corresponding numerical solution verify the accuracy of the algorithm.In terms of inversion,the paper explored the inversion technology of natural potential current source based on regularization method.The Tikhonov regularization idea is used to construct the inversion objective function.By studying the key issues such as the data objective function,the model constraint objective function,the selection of the regularization factor and the optimal solution of the inversion objective function,the natural potential two-dimensional regularization inversion is realized.play.When constructing the model constraint objective function,by introducing a depth weighting function,the inversion accuracy of the underground current source is effectively improved.In order to further verify the practicability of the algorithm,the measured data collected from the uranium mining area in the southern margin of the Yili Basin were inverted.The inversion results of four survey lines were selected and combined with the existing geological data for comprehensive interpretation,the spatial location of the underground uranium ore body was inferred,which was consistent with the drilling data fed back later.The research work provides strong technical support for the application of the spontaneous potential method to the exploration of sandstone-type uranium deposits in the interlayer oxidation zone and the precise delineation of the spatial location of uranium deposits.