A Altitude Correction Method for Earth-Space-Time-Domain Electromagnetic Data

Abstract

The invention relates to a ground-airborne time-domain electromagnetic data height correction method. The method mainly comprises the following steps that: an unmanned aerial vehicle or an airship is adopted to perform flight measurement in the air; electromagnetic noise removal and bipolar overlay sampling are performed on measured data; Kriging interpolation and double-cubic B spline interpolation are adopted to perform uniform interpolation on the magnetic field change rate of each measuring point in flight measurement, wherein the magnetic field change rate is expressed by a formula mentioned in the descriptions in the invention, so that magnetic field change rates in two-dimensional uniform grids can be obtained; and an inverse continuation theory is adopted to perform continuation calculation on a magnetic field change rate measured at a height where z=-h in the air, so that the magnetic field change rate data of a site on the ground where z=0 can be obtained, and therefore, flight height correction is realized. With the ground-airborne time-domain electromagnetic data height correction method adopted, the problem of ignoring of height in the prior art in which an LOTEM method is adopted to interpret ground-airborne time-domain electromagnetic data can be solved; the magnetic field change rate data can be directly used to perform correction, and the magnetic field change rate is not required to be converted into a magnetic field to perform correction, and only three flight test lines are just required, so that height correction can be carried out, and a calculation process only involves interpolation and Fourier transform. The ground-airborne time-domain electromagnetic data height correction method has the advantages of simple calculation and high computing speed.

Description

technical field [0001] The invention relates to an airborne geophysical prospecting method in geophysical prospecting, in particular to a height correction method for ground-space-time-domain electromagnetic detection data. Background technique [0002] Ground-airborne Time-domain electromagnetic system (GATEM for short) is to excite the earth with a bipolar pulse current through a long grounded wire, forming a large area of ​​electromagnetic waves in space, and passing them on an unmanned aerial vehicle or airship. The on-board receiving system conducts flight surveys to obtain data on the rate of change of the underground magnetic field. Through resistivity imaging, the existence of underground abnormal geological bodies can be found, and the electrical structure and spatial distribution of the abnormal bodies can be determined. The ground-space time-domain electromagnetic detection method not only has the advantages of high detection efficiency of the airborne time-domain...

AI Technical Summary

Problems solved by technology

[0005] The above prior art, one discloses the method and interpretation method of electrical source transient electromagnetic ground-air detection, but does not correct the altitude; the other provides an airborne electromagnetic altitude correction method, although a uniform half-space model can be used, etc. However, due to the fact that the actual geological situation is a complex geological structure, the induced electromotive force has a transition process between different media, so it is impossible to accurately find the resistivity when using the uniform half-space model equivalent. value, so the height can only be corrected correctly if the exact conductance value of the subsurface and its depth are known

Images