The Study On Quality Factor Q Estimation Method Based On Pre-stack Seismic Absorption And Attenuation

With the deep research on the theory of seismic wave absorption and attenuation,the parameters of the absorption and attenuation properties describing rock elasticity have attracted more and more attention in the application of oil and gas exploration.And it plays a more and more important role in the processing of real data.As an important parameter to characterize the viscoelastic attenuation,the inversion and estimation theory of reservoir quality factor Q value is always the hotspot of seismic exploration.In order to improve the resolution of seismic data,inverse Q filtering,reservoir prediction and reservoir characterization,accurate and reliable quality factor Q calculation is of great significance.On the basis of summarizing the theory of seismic wave absorption and attenuation and the method of pre-stack quality factor Q estimation,it points out the existing problems of quality factor estimation and Application,and put the focus of the study on the pre-stack quality factor estimation method.Combined with the definition of quality factor,it compares the range and accuracy of the various estimation methods from the theory and application results,and analyzes the factors that affect the accuracy of the estimation on this basis.Based on the above conditions,a method for estimating Q of the time-frequency spectrum mean based on S transform is proposed,and realizes the application of the model and the actual data.Finally,the paper analyzes the risk of quality factor in application.The results show that:(1)There are many problems in the existing quality factor Q estimation methods and Applications,including the model design and parameter selection,sequent Q inversion,pre-stack Q inversion,attenuation detectability and gas reservoir sensitivity prediction.(2)Based on spectral ratio method to calculate the Q value,S transform has the highest accuracy and better noise immunity compared with STFT and WT.(3)Due to the influence of the thin layer effect,when the reservoir attenuation is affected by the thickness of the reservoir or the parameters of the medium properties and attenuation does not reflect the reservoir information or be submerged by noise,It is not reasonable to accurately estimate or estimate the reservior quality factor Q value by attenuation seismic response.In the study of estimation methods,the factors of geometric attenuation,scattering and transmission are not negligible.(4)The improved time-frequency spectrum mean method of estimating Q,which is based on the superposition of time-frequency domain,has a good effect in the theoretical model and practical application.(5)Because of the interference effect of the thin layer,the decrease of attenuation and the interference of aquifer,relying solely on the estimation of the quality factor for reservoir prediction is of high risk.It is an effective way to avoid fatal error only by combining many factors(such as speed).