Two-dimensional Forward And Inversion Of Spontaneous Potential Of Sandstone-type Uranium Deposit In Interlayer Oxidation Zone

The sandstone uranium deposit is one of the most important uranium deposit types in the world,which accounts for a great part of the uranium resource reserves in China.Sandstone-type uranium deposits generally take groundwater as the carrier and occur activation,migration,deposition and enrichment in interlayer oxidation zone sandstone layers.Due to the obvious natural potential anomaly caused by the electrochemical reaction of uranium,self-potential method has become one of the effective methods for locating and delineating sandstone-type uranium deposits.However,there are few studies on the formation mechanism of self-potential field in interlayer oxidation zone sandstone-type uranium deposits.In this paper,the formation mechanism of self-potential field in interlayer oxidation zone sandstone-type uranium deposit is studied,and the forward and inversion of natural electric field are carried out.In this paper,the formation mechanism of self-potential field in interlayer oxidation zone sandstone-type uranium deposit is introduced,and the equivalent model of selfpotential field based on current density is proposed,on the basis of clarifying the formation mechanism of spontaneous potential in interlayer oxidation zone sandstone-type uranium deposits,the basic equations and boundary conditions of self-potential field are derived,and two-dimensional forward modeling of self-potential field is realized based on the finite difference method,the response characteristics of background resistivity,orebody resistivity,orebody dip angle,orebody shape,horizontal and vertical spacing of multiorebody to natural electric field are analyzed.On the basis of two-dimensional forward modeling,based on the idea of regularization,the two-dimensional regularization inversion of natural potential is studied,and the objective function considering the prior geoelectric model and the smooth constraint of the model is established,two regularization factor selection algorithms of Lcurve and GCV are designed,and the reliability and validity of the inversion algorithm are verified by a large number of typical auto-electric models and measured data,the current density distribution and vector map obtained by inversion can effectively determine the occurrence and location of orebody,and a set of self-potential data processing software has been developed.Finally,the software is used to process and invert the self-potential data collected in Songliao Basin,and good application results are obtained.