The Spectral Decomposition Technology Based On Generalized S Transform And Its Application In Reservoir Detection

The traditional Fourier analysis method is used to study actual signals,and it cannot describe time-frequency information.Then,I introduce short-time Fourier transform,S transform and generalized S transform.A variety of theoretical models are simulated,the experimental results show that the generalized S transform has good time-frequency focusing function and precise positioning function.Therefore,the generalized S transform is used to analyze identification of thin layer and low-frequency shadow detection of reservoirs.The results of the simulation calculation of the horizontal thin layer show that the spectral decomposition technique based on generalized S transform can well characterize the local information of thin layer.In this paper,the application of generalized S transformation in recognition of seismic thin layer is discussed from three directions,namely,instantaneous amplitude,dominant frequency section and high resolution section based on generalized S transform.Under certain conditions,the low-frequency shadow phenomenon can be used as an important indicator for prediction of hydrocarbon reservoirs.The favorable sign for identification of oil and gas reservoirs:at low frequency,the performance is“strong reservoir and bright shadow”;at high frequency,the performance is “strong reservoir and weak shadow”.Studying the relationship between low-frequency shadow and reservoir characteristics,numerical calculation is made for four different models of oil and gas reservoirs.The results reveal that When the Q value of reservoir is low and the reservoir reaches a certain thickness,the low-frequency shadow phenomenon will become more obvious.Then,the spectral decomposition technique of time-frequency analysis method is used to predict the oil and gas reservoir in the actual seismic data.The contrast results show that the detection of low-frequency shadow based on generalized S transform achieves better results.Combined with the acoustic well logs in the seismic section,we can infer that the red frame is gas-bearing reservoir.In the end,horizontally tracing the time-frequency spectrum of continuous seismic traces and analyzing the maximum and instantaneous amplitude section based on generalized S transform,the lateral variation of reservoirs can be well predicted.