Thin Interbed Analysis Based On The Time-Frequency Analysis

The oilfield industry in China has entered into the complicated stage of oil and gas field development, the accuracy requirement to seismic exploration is increasing higher and higher, how to conduct the oil and gas exploration in the interlamination is a problem needed to be solved by the scientific workers.Seismic Sequence Interface Detection is to detect the sedimentary sequence underground using seismic signals which are the reflected complex signals from each layer underground, how to detect the underground sedimentary sequence from the seismic signals makes it urgent to seek after a time-frequency analysis method with high resolution.Spectral analysis is the basis of seismic data processing. Because seismic signal is a complex non-stationary series, a suitable time-frequency distribution is the key for ensuring the quality of seismic data time-frequency analysis. Time-Frequency analysis is a very effective way to analyze non-stationary signal, it can obtain high frequency resolution in low-frequency and high time resolution in high-frequency. It can transform one-dimension time signal to two-dimension time-frequency spectrum. This paper has selected Generalized S Transform as time-frequency analysis tool, for it has higher resolution and better adaptability time window, and its length and size can adjust. For the different seismic data, we can obtain their time-frequency spectrum only through changing the parameters of time window. So the two-dimension time-frequency domain filter is much more flexible than normal frequency domain filter. In seismic cross-section because the frequency of seismic data is lower. After we do time-frequency decomposition for them, we can extract higher single-frequency section, the thin-layer can display more clearly and the complex structure can depict more fine.This article has combined the study of thin-layer reflection coefficient with GST time-frequency analysis, processed the high resolution seismic cross-section. It also introduces a method of attenuation compensation based on the GST. As the stratum is not completely ideal elastic media, which will result in attenuation frequency energy because of the transmission of seismic wave. The attenuation compensation method based on GST overcomes inadequate aspect of the short-time Fourier transform and wavelet transform. The time-dependent absorption effects can be eliminated. The effect of this method in high resolution processing is clear after tested by artificial model and real seismic data.The simulation demonstrates that GST is able to exactly describe the structural details in the thin interbred. Utilizing GST as a preferable tool for time-frequency spectral analysis of seismic signal, the paper respectively explores non-stationary decomposition, detecting the low frequency shadow related to the gas concentration, and the stratigraphic analysis with high resolution of thin bed. The theoretic model and actual seismic data prove that GST is a feasible and effective method in extracting the characteristic information for its anti-interference ability. According to research goal, we can reasonably select instantaneous frequency amplitude-spectrum profile, frequency ranges seismic profile and single frequency seismic profile to identify the characteristic information, hence providing the reliable basis for the further processing and interpretation of seismic data.