Several Time-frequency Analysis Technology And Their Application Research In Seismic Exploration For Oil And Gas

The different frequency component of seismic signal and its statisticcharacteristic vary unsteadily over time. The variation and abnormity record s presentabundant information of the features of reflecting medium underground. Throughspectral decomposition, the seismic data could help analyze the depth of reservoir andidentify reservoir etc.This thesis, based on the theory of linear Time-Frequency Analysis, presents thebasic concepts of unsteady signal and Time-Frequency Analysis and main mathematicacknowledges, and clarifies the relations between each linear Time-FrequencyAnalysis and its own strengths and shortcomings. This thesis mainly statess-transform, generalized S-transform and how to practice Algorithm. Throughcomparison it comes to conclusion that generalized S-transform has highertime-frequency resolution, and flexible and alterable time-window applying to avariety of complex signals.This thesis, based on Hilbert transform, introduces instantaneous attribute and itsapplication in the seismic data interpretation,analyzes the deficiency of instantaneousattribute, clarifying that it is not applicable to any seismic signals with complexchanges of frequency. According to the concept of instantaneous attribute ofprobability theory, the instantaneous attribute, in accordance with TFA has beenintroduced in this thesis, which make the extracted instantaneous parameters moreconvincing in demonstrating the structure of underground and lithology information,and build model to analyze the relation between instantaneous attribute and thethickness of lamina, providing proof in the explanation of practical data.This thesis chooses the wavelet transform approach to expand the frequency ofseismic signals, so as to achieve the purpose of advancing the resolution of seismicdata. This method combines the advantage of Wavelet Transform and spectrumequibalance, proceeding spectrum equalization on different dimensions of signalsafter Wavelet Transform, which is to reach the purpose of improving the final resolution of seismic signal. And utilizing practical seismic data to state this method iseffective and reliable in the terms of improving resolution.By viscous wave equation, this thesis simulates the characters of Porous m Byviscous wave equation, this thesis simulates the characters of Porous medium fluidwhich are viscousness, diffuse, and low-frequency shadow phenomenon caused bylow Q. This provide a new approach to indicate the mechanism of low-frequencyshadow. The practice of observing low-frequency shadow by analyzing practicalReservoir seismic data verify that the phenomenon of low-frequency shadow hassomething to do with oil and gas in reservoir. In a word, this thesis concludes thatutilizing the relative changes of the size of Low, medium and high energy spectrumreflected by seismic as good marks to identify oil and gas reservoir.