Static correction method of CSAMT data

Abstract

The invention relates to a static correction method of CSAMT data. The method comprises the following steps of fitting a controllable source audio magnetotelluric original signal according to apparentresistivity data of controllable source audio magnetotelluric discrete points and performing empirical mode decomposition on each IMF component; identifying a static effect according to a correlationcoefficient between the apparent resistivity values of all frequency points of observation points and reference points, and if the static effect exists, reconstructing the original signal according to each IMF component to obtain a statically corrected controllable source audio frequency magnetotelluric reconstruction signal s'(t). The method can keep the information of an abnormal body in the original data during suppression of the static effect, so that the abnormal body is not distorted.

Description

technical field [0001] The invention relates to a static correction method for CSAMT data. Background technique [0002] Controlled Source Audio-frequency Magnetotellurics (Controlled Source Audio-frequency Magnetotellurics, referred to as CSAMT Carnia resistivity sounding curve, so also known as Controlled Source Audio-frequency Magnetotellurics method, has high work efficiency, large exploration depth range, and spatial resolution. The advantages of high efficiency, small impact of terrain, and small effect of high-resistance electric shielding. During the signal acquisition process of CSAMT, there are often local conductive inhomogeneities on the surface or near the surface. When the current flows through the surface of the inhomogeneity, charges will be formed. The cumulative effect causes the distortion of the electric field and produces a static effect. In the "apparent resistivity-frequency" double-logarithmic coordinate system, the apparent resistivity curves of adja...

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Problems solved by technology

The effect of the curve translation method largely depends on the level of cognition of the data processing personnel. The judgment of static effects and processing experience play a key role. It is easy to mistake those abnormalities that are not caused by static effects as static The effect is "corrected"; for some simple static effects of terrain background, especially those caused by terrain effects, numerical simulation methods can be used to identify and make corrections, but these are often unknown in actual field conditions , so it can only be used as a reference research; the joint inversion method is equivalent to repeating two geophysical methods, which is expensive and not practical; wavelet transform is a variable window transform, which converts the static Effects and large structural anomalies can be distinguished mathematically intuitively, with high resolution and correction accuracy. However, the problem with the wavelet method is the selection of wavelet basis functions. The difference in wavelet basis selection and the number of decomposition layers will lead to decomposition. There is a large difference in the results, which will affect the subsequent static correction effect

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