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Research of Extract Method of Seismic Signal’s Instantaneous Parameters Based on Wavelet Transform

Author: WuWeiLong
Tutor: LiuXia
School: Northeast University of Petroleum
Course: Control Theory and Control Engineering
Keywords: seismic signal wavelet transform instantaneous parameters high resolution
CLC: O174.22
Type: Master's thesis
Year: 2011
Downloads: 117
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Abstract


Instantaneous parameter of seismic signal possesses a wealth of the geological information. Through the research to the Instantaneous parameter of seismic signal, we can explain and get important information about the ground, faults, cracks and lithological change. Wavelet transform is a time-scale domain analysis technique grown up in recent years. When using analytic wavelet to make the wavelet decomposition to the real signal, we can find under instantaneous parameter of each scale. Instantaneous parameters extracted in the wavelet domain have good noise immunity and good reliability, because the wavelet transform own the characteristics of frequency division and the function of noise removed. Therefore the study mainly researches the extract method of seismic signal’s instantaneous parameters based on wavelet transform.The article introduced two methods, using the Hilbert transformation to extract the instantaneous parameter of seismic signal and using the wavelet transformation to extract the instantaneous parameter of seismic signal, By contrast the analysis effect of two methods, both Hilbert transform and wavelet transform can extract the instantaneous parameter of seismic signal. But Hilbert transform is very sensitive to noises, the instantaneous parameter extracted by wavelet transform has good noise immunity, But Hilbert transform is very sensitive to noises, the instantaneous parameter extracted by wavelet transform has good noise immunity, during extracting the instantaneous parameter of seismic signals by wavelet transform. There are small events can’t be distinguished and there are negative frequency components in the instantaneous frequency, all of these affect the accuracy and resolution. Therefore, this article improved the conventional wavelet transform, to reform the wave function by the constant, according to earthquake frequency data to choose the suitable wave function, make the center of the signal frequency and the bandwidth nearer to the seismic signal, noise immunity is greater. Improved the calculation method of instantaneous frequency and combined the analytic signal method and differential plase detection to resolve negative frequency phenomenon and extract the instantaneous parameter of seismic signal accurately.To the needs of the high resolution, it gets high resolution instantaneous parameters through calculating the derivative of the seismic signals to increase the dominant frequency and then to make wavelet transform to the seismic signals worked. Keep the truth of the information and improve its quality, then extracted high resolution instantaneous parameters.

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CLC: > Mathematical sciences and chemical > Mathematics > Mathematical Analysis > Theory of functions > Fourier analysis ( classical harmonic analysis ) > Fourier integral ( Fourier transform )
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