Research On Frequency-Variable Q-Value Extraction And Compensation Method Of VSP Data Based On Time-Frequency Analysis

When the seismic wave propagates in the medium,due to the viscoelasticity of the medium,the seismic wave will attenuate,the main frequency of the seismic wave moves to the low frequency direction,the frequency band becomes narrower,and the continuity of the in-phase axis becomes worse,which leads to the decline of the resolution of the seismic data.Inverse Q filtering is helpful to improve the signal-to-noise ratio and resolution of seismic waves and improve the imaging accuracy.At the same time,attenuation is also an important seismic attribute of oil-gas reservoir prediction.Therefore,the research on accurate quality factor estimation and inverse Q filter compensation method is of great significance for deep and high-resolution seismic exploration.The actual seismic exploration has proved that the seismic wave propagates in the underground medium has the dispersion phenomenon,the quality factor Q changes with the frequency transformation.The traditional Q-value estimation and inverse Q filtering methods do not take its frequency-varying characteristics into account.On the basis of systematic research on time-frequency analysis method,based on the generalized S-transform method,the frequency-varying Q-value estimation method of VSP seismic exploration data is established and compared with the conventional Q-value extraction method.A frequency-varying inverse Q filtering method for VSP data is established.Through the data test,the frequency-varying Q-value inverse Q filter can better compensate the energy of seismic waves.