Numerical Calculation of Borehole Electrical Survey in Layered Media and Its Applications

The integral formula of Gauss-Lagrange has been applied to theoretically calculate ΔV1 (potential gradient), and ρa of the surface-borehole method of borehole electric exploration. Lots of forward calculation data show that the survey of surface-borehole method can obtain step-anomalies under the layered media condition, which correspond to geo-electric layers. Over-burden low resistivity layers and sandwich low resistivity layers have large influence on the result of borehole electric survey. Heavy overburden is harmful to this kind of working method. When analyzing field dada, the normal field feature of ΔV1 and ρa must be considered. Analysis of the abnormal field ΔV1" from the corrected normal field can achieve good effects.