The Method Study To Increase Seismic Resolution Based On The Time-Frequency Spectrum

In the field of seismic exploration,"three-high" processing has always been the central topic of people's discussion,and the fundamental method to solve the difficulties in seismic exploration.High resolution in "three high" can help increase the richness of seismic data and show more detailed geological information.However,due to the influence of media characteristics and seismic data acquisition conditions,the original seismic data cannot meet the research requirements.In the factors that affect the resolution of seismic data,the characteristics of earth absorption and wavelet band are two key factors.Quality factor Q is a general parameter of quantization absorption,but how to obtain stable and accurate Q value is always a hot topic.Because the absorption effect of the earth is not only related to the propagation medium,but also to the frequency of the seismic wavelet,it is proposed to carry out the Q value estimation in time-frequency domain.However,the traditional time-frequency analysis method has a low resolution and cannot provide a time-frequency distribution with sufficient precision.Therefore,this paper proposes to estimate the Q value by using the inverse time-frequency spectrum.Compared with the traditional method,inverse time-frequency spectrum is more focused,more stable,and less affected by random noise,which improves the good basic data for calculating the Q value.Inverse Q filtering is general method to compensate absorbed energy of seismic data use the Q value.However,the traditional filtering method may lead to instability problems.By introducing the stability factor,this paper realizes the stable inverse Q filtering method.The correctness and validity of the method are verified by theoretical and practical data.Band-limited Wavelet will make high frequency attenuation even disappear.The most direct performance is wavelet duration extended,multiple stratigraphic reflection wavelet superimposed.The result is a vague geological structure,deconvolution is usually used.The traditional deconvolution method is based on the convolution theory.Under the assumption of the minimum phase,the wavelet influence is eliminated by estimating the wavelet spectrum.Spectrum is generally obtained by Fourier transform,with an average effect.However,frequency of seismic data in different time is different,so the precision of Fourier analysis is not enough.In order to make up the deficiency of traditional methods,the nonstationary deconvolution method based on Gabor Transformation is implemented.The method is processed in two steps.The first step is to solve the problem of seismic energy balance by estimating the attenuation function on the time-frequency spectrum.The second step is to estimate the wavelet spectrum by calculating the spectrum envelope of each moment.Then,the nonstationary deconvolution is performed under the assumption of the minimum phase.The method is applied to the actual data of a working area and has obtained good results.The resolution of seismic data after processed is obviously improved,the geological structure is clearer and the boundary is more obvious.