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Time frequency analysis method of magnetotelluric impedance estimation

A technique for magnetotelluric and impedance estimation, applied in electric/magnetic exploration, acoustic re-radiation, geophysical measurement, etc., can solve problems such as incompatibility of non-stationary characteristics of MT signals, and achieve more robust estimation results , Realize the effect of robust estimation and strong noise suppression ability

Inactive Publication Date: 2017-02-22
HUNAN UNIV OF ARTS & SCI
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Problems solved by technology

The most traditional method for processing MT signals is the Fourier transform, and the Fourier transform is based on a stationary signal, which is not compatible with the non-stationary characteristics of the MT signal. Therefore, using the Fourier transform to analyze the MT signal has obvious defects.

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  • Time frequency analysis method of magnetotelluric impedance estimation
  • Time frequency analysis method of magnetotelluric impedance estimation
  • Time frequency analysis method of magnetotelluric impedance estimation

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Embodiment 1

[0026] Such as figure 1 As shown, the time-frequency analysis method for magnetotelluric impedance estimation includes the following steps:

[0027] (1) Using the empirical mode decomposition method, the four components of the magnetotelluric signal H x 、E y 、H y 、E x be broken down separately. Decomposition process such as figure 2 As shown, the time series signals on each component of the magnetotelluric signal are respectively set as , first determine the All the extreme points on , and then fit all the extreme points with a curve to get the signal The upper and lower envelope curves of are respectively set as and , then the average curve of the upper and lower envelopes for: ; use minus After that, the remaining part is obtained as ,which is: .

[0028] Ideally, should be an intrinsic mode function because The construction process of is to make it satisfy the condition of intrinsic mode function. However, due to the overshoot and subduct...

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Abstract

The invention discloses a time frequency analysis method of magnetotelluric impedance estimation. By adopting empirical mode decomposition technology of Hilbert-Huang transform, a magnetotelluric signal is decomposed to acquire mode functions of various orders for the Hilbert transform, and the time frequency spectrums of the four components of the magnetotelluric signal are acquired, and acquired instant amplitudes are used to replace Fourier spectrum of a conventional Fourier method, and then the instant amplitudes are introduced in a minimal quadratic equation to solve impedance tensors of time frequency points, and then the impedance tensor elements of the various time frequency points are calculated, and in addition, the time frequency power spectrogram of the magnetotelluric signal is converted into a time frequency impedance spectrogram. In the time frequency impedance magnetotelluric, the response function values of the various time frequency points having same instant frequencies are accumulated together, and then the acquired sum is divided by the number of the time frequency point, and the mean value thereof is a response function estimated value of a frequency value. The time frequency analysis method of the magnetotelluric impedance estimation is advantageous in that realizing of robust estimation is facilitated, and the impedance elements acquired by adopting the method conform to reality of a stratum structure, and a stronger noise inhibition capability is provided, and an estimation result is more robust.

Description

technical field [0001] The invention relates to the field of magnetotelluric (Magnetotelluric, MT) data processing, in particular to a time-frequency analysis method capable of improving the estimation accuracy and interpretability of magnetotelluric impedance. Background technique [0002] Magnetotelluric sounding (MT) is an electromagnetic prospecting method that uses natural alternating electromagnetic field as the field source. Its electromagnetic field signal is weak, wide in frequency, and easily interfered by various noises. It is a typical nonlinear and non-stationary signal. The most traditional method to deal with MT signal is Fourier transform, and Fourier transform is based on the theory of stationary signal, which is not suitable for the non-stationary characteristics of MT signal, so using Fourier transform to analyze MT signal has obvious defects. In the magnetotelluric sounding method, data analysis, quantitative inversion and geological interpretation must b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V3/38G01V3/08
CPCG01V3/38G01V3/08
Inventor 蔡剑华郭杰荣王先春黎小琴胡惟文彭元杰刘长青熊锐
Owner HUNAN UNIV OF ARTS & SCI
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