Transient electromagnetic inversion method based on transverse smooth constraint

Abstract

The invention discloses a transient electromagnetic inversion method based on transverse smooth constraint and is applied to the earth exploration field. The method comprises steps that S1, a primary pulse magnetic field is emitted to the underground, a secondary magnetic field excited by induction eddy current generated by an underground conductive geologic body under the excitation action of the primary pulse magnetic field is measured, secondary magnetic field data acquired through measurement is taken as observation data; S2, an initial inversion model is constructed; S3, a mismatching functional between the observation data and forward theory data is constructed; S4, a vertical constraint functional for constraining electric parameter change of the conductive geologic body is constructed; S5, a transverse constraint functional for constraining electric parameter change of the conductive geologic body among measurement points is constructed; S6, an inversion target function is constructed on the basis of the mismatching functional, the vertical constraint functional and the transverse constraint functional; and S7, the initial inversion model is taken as initial conditions, an electric parameter corresponding to a smallest inversion target function value is solved, and the underground structure is reconstructed according to the electric parameter. The method is advantaged in that the underground structure acquired on the basis of inversion imaging results is more accurate and reliable.

Description

technical field [0001] The invention relates to the field of geophysical exploration, and more specifically, to a transient electromagnetic inversion method. Background technique [0002] As a powerful means of geophysical exploration, transient electromagnetic method can solve various geophysical problems such as mineral exploration, energy, engineering, hydrology, environmental geological survey, and archaeological exploration. It uses step waves or other pulse currents to emit a pulsed magnetic field underground, and the underground conductive geological body generates an induced eddy current under the excitation of the primary field, and then stimulates a secondary magnetic field. When the emission current is turned off, the primary field disappears, and the subsurface eddy current decays with time, and its decay time is related to the electrical parameters (volume, structure, buried depth, resistivity, conductivity, dielectric constant) of the conductive geological body...

AI Technical Summary

Problems solved by technology

Current regularized inversion methods are limited to single-point inversion and cannot impose constraints between adjacent measurement points

Images