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Time-frequency analysis method

A technology of time-frequency analysis and time-spectrum, applied in the field of seismic signal spectrum analysis

Active Publication Date: 2014-04-16
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In order to eliminate the influence of cross-terms, in the 1960s, many solutions were proposed, such as pseudo-Pwvd, smoothed Fwvd, smoothed pseudo-Spwvd, Cwd distribution, etc., which are collectively called Cohen-like bilinear time-frequency distributions. These methods can only eliminate certain cross term within degree range

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Embodiment 1

[0098] First, the synthetic seismic trace is constructed by the Morlet wavelet, such as figure 2 shown. It contains two combinations: three adjacent time and the same main frequency 20Hz wavelet; two same time position and main frequency are 20Hz and 40Hz respectively. The model design is mainly to test the accuracy of the method of the present invention, and at the same time to test the vertical time resolution and horizontal frequency resolution in the frequency spectrum.

[0099] Perform Gabor time-frequency processing, WVD time-frequency processing, exponential window smoothing pseudo-Spwvd time-frequency processing and the present invention's time-frequency processing respectively to the single channel model data, and the results obtained are respectively as follows Figure 3 to Figure 6 shown.

[0100] right Figure 3 to Figure 6 It can be seen that the spectral resolution is the lowest when Gabor is used, and the vertical and horizontal resolution is limited by the ...

Embodiment 2

[0102] Create a wedge-shaped thin-layer model, such as Figure 7 As shown, the wavelet is selected from Leike, and the main frequency is 15Hz. Input the model data, respectively do Gabor time-frequency processing, exponential window smoothing pseudo-Spwvd time-frequency processing and the time-frequency processing of the present invention. The frequency division results are as follows Figure 8 to Figure 10 As shown, they correspond to the 20Hz single-frequency profiles of the three methods.

[0103] Compare Figure 8 to Figure 10 It can be seen that the present invention has higher single-frequency thin-bed resolution capability in thin-interbed seismic frequency-division applications.

Embodiment 3

[0105] The study of fractured-vuggy carbonatite reservoirs is one of the key points of exploration in the Tarim area of ​​China. Figure 11 It is a physical model based on fracture-cavity heterogeneity research, which is composed of caves of different scales, and shows strong amplitude on the seismic section.

[0106] Input the crack-cavity model signal, make Gabor time-frequency distribution, ST time-frequency distribution, CWT time-frequency distribution and the time-frequency distribution of the present invention respectively, choose 25Hz single-frequency profile to compare, the results obtained are respectively as follows Figure 12 to Figure 15 shown.

[0107] Compare Figure 12 to Figure 15 It can be seen that the frequency division accuracy of the present invention is better for caves of different scales, and the distinction between caves is obvious and easy to identify. layer prediction.

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Abstract

The invention provides a time-frequency analysis method, and belongs to the field of seismic signal spectral analysis. The time-frequency analysis method comprises the steps that (1) a single seismic trace signal u(t) is input; (2) Gabor time-frequency processing is carried out on the u(t), and a Gabor time-frequency spectrum Gabor (t, f) is obtained; (3) meanwhile, plural conversion is carried out on the u(t) according to Hilbert conversion to obtain a plural signal z(t), and then index window smooth fake Spwvd time-frequency processing is carried out on the plural signal z(t) to obtain an Spwvd time-frequency spectrum Spwvd (t, f); (4) same value processing is carried out on the amplitude value of the Gabor time-frequency spectrum Gabor (t, f), and then convolution is carried out on the processed Gabor time-frequency spectrum Gabor (t, f) and the Spwvd time-frequency spectrum Spwvd (t, f) to obtain a united time-frequency spectrum SG (t, f); (5) the united time-frequency spectrum SG (t, f) is output.

Description

technical field [0001] The invention belongs to the field of frequency spectrum analysis of seismic signals, and in particular relates to a time-frequency analysis method. Background technique [0002] Time-spectrum analysis technology provides a new way of thinking for reservoir prediction and oil and gas detection. Researchers can identify geological anomalies by frequency-dividing data volumes. Seismic signals are non-stationary signals. The traditional Fourier transform can only map the signal from the time domain to the frequency domain, and cannot effectively detect the frequency change of the non-stationary signal with time, so it is difficult to analyze the local characteristics of the signal. Time-frequency analysis maps the one-dimensional time-domain signal and frequency-domain signal to a two-dimensional time-frequency plane to obtain the time-frequency distribution of the signal, so that the signal components can be distinguished and extracted in the time-freque...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/30
Inventor 余波
Owner CHINA PETROLEUM & CHEM CORP