The Study Of Seismic Attenuation Tomography Inversion Based On Spectrum Ratio Method

When the seismic wave propagates in the ground medium,the resolution of the seismic data and the accuracy of the seismic data processing and interpretation are reduced due to the strong absorption of the underground medium.Therefore,it is an effective way to select the appropriate parameters to describe the absorption attenuation of the formation effectively.It is an effective way to deal with underground high resolution and high precision processing and interpretation.The quality factor Q is one of the important parameters that we use to describe the elastic parameters of the rock effectively.It is an effective way to improve the resolution of seismic data by using the quality factor Q to measure the absorption attenuation of the seismic wave energy in the medium,and it is also an effective way to improve the interpretation accuracy of the oil and gas strata.In recent years,many scholars have proposed a variety of methods to calculate the Q value,in which the spectral ratio method is the most widely used Q value estimation method.Considering the problem of poor accuracy and stability in many direct methods of calculating Q-value,many experts have proposed the iterative fitting method to carry out Q inversion.The spectral ratio attenuation tomography method is a method of obtaining Q values by iterative fitting.In this paper,the attenuation mechanism of seismic wave and the factors that affect the attenuation of seismic wave are introduced.The attenuation parameters of seismic wave and their relationship are combed.Then,several traditional methods of calculating Q value are discussed and compared.In particular,the spectral ratio method is described in detail.On the basis of the basic theory of spectral ratio method,the method is improved and the tomographic method is combined to invert Q values.The decaying equations are obtained by solving the chromatographic sensitive kernel function and the slope residual in the spectral ratio attenuation tomography method.Due to the unavoidable sparsity of the chromatographic matrix,we use the least squares QR decomposition method to solve it.The method makes full use of the advantages of spectral ratio method in stability and precision,as well as the advantages of the computational efficiency of the traveltime tomography method.This not only improves the stability of the inversion but also ensures the accuracy of the inversion and improves the computational efficiency.The feasibility of the spectral ratio attenuation tomography method is verified by the model test.Finally,the quality factor Q obtained by the spectral attenuation method is applied to the compensation of seismic attenuation and absorption.The resulting Q value is used for the most commonly used compensation method-the inverse Q filtering method yields good results.