The Study Of Frequency Domain Electromagnetic Methods Impacted By Displacement Current

Abstract::Domain electromagnetic methods are important geophysical exploration methods, to study the prospecting depth and forward simulation are important topics about it. Most of the studies about frequency domain electromagnetic methods did not consider of displacement current at present. But the work-frequency does not meet the conditions of characteristic frequency (specific value of displacement current and conduction current) ω0=εω/σ<<1in the shallow exploration area, displacement current will impact the propagation characteristics of electromagnetic wave, such as skin depth. With Maxwell equations, at first we analyze the influence of displacement current to the propagation of electromagnetic waves according to the expression of skin depth. Afterward under the conditions where the displacement current and conduction current are both considered, using the generalized reflection coefficient, we derive the accurate calculation of skin depth of the electromagnetic wave in layered media, analyze the calculation errors of ignoring the volatilities of electromagnetic wave. The results show:When characteristic frequency ω0≥0.1, ignoring the displacement current will lead to5%calculation error, pointed out the necessity of the displacement current to the transmission of high frequency electromagnetic wave; the influence of reflection and refraction at the interface to skin depth of the electromagnetic wave in layered media relates to power difference between the two layer.It is well known that the critical distortion to resistivity sounding curves could be produced by shallow inhomogeneous bodies.According to the skin effect of high frequency electromagnetic wave, this paper obtained the influence work frequency of sounding curve、combined the finite element method to do the forward simulation,discussed the influencing factor and its rules of transverse non-uniformity.