The Study On Seismic Characterization Of Fractured Reservoir

The study of seismic characterization of fractured reservoir can obtain related suitable fracture parameters,and effectively describe the development and distribution of fractured reservoir,which plays an important role in oil and gas reservoir exploration and development.However,in the actual reservoir,the fractures are more complex,will make a certain challenge for the fracture characterization.Therefore,starting from the rock physical modeling,according to the corresponding reservoir characteristics,the appropriate rock physical models can be established,and the response of velocity,attenuation and reflection coefficients for fractured reservoirs are analyzed theoretically.For any fractured reservoir,the exact difference seismic data AVAz inversion method with strong applicability is derived,which can effectively obtain relatively accurate fracture characterization parameters and is applicable to any anisotropic media.The multi-source information can be fused to comprehensively describe the development of fractured reservoir,in terms of attributes and inversion results.Through the application of the model and actual data,the applicability and accuracy of the proposed methods are further verified.Firstly,according to different TI anisotropic fractured reservoirs,the suitable rock physical modeling is carried out.For HTI fractured reservoirs,in order to eliminate the defects of Hudson model in the assumption of small fracture density,the Padéapproximation is introduced to add HTI fractures.The modeling results are more accurate and conform to the characteristics of the actual fractured reservoir,which is of great significance for the subsequent fracture parameters prediction,forward theoretical analysis and fracture characterization.In addition,for the modeling of TTI anisotropic fractured reservoir with porous background media,the Backus average method is used to obtain the effective modulus and get the stiffness matrix of basic VTI media.Through Bond’s transform,the effective modulus of general TTI media can be effectively obtained from the VTI or HTI models described before.Furthermore,based on the rock physical modeling,the velocity and attenuation properties of fractured reservoirs are analyzed,which are helpful to further understand the influence of different fractures on the anisotropy characteristics of the reservoir.Based on the 2D exact forward modeling method for arbitrary anisotropic media,it can be extended to3 D data,the exact forward modeling equations which are more widely used for general fractured formations is derived by introducing the information of incident angles and azimuths.The accuracy of the method is further verified by the model examples.Then,using the linear approximation equation of arbitrary anisotropic medium,the inversion method of wide azimuth pre-stack difference seismic data is derived to obtain the sensitive parameters for fracture characterization.Based on the Bayesian framework,the differential hyper-Laplacian blocky constraint is introduced to select the relevant parameters according to the characteristics of the fracture parameters.The inversion results have higher stability and accuracy.The inversion results of model and actual data can further verify the effectiveness of the proposed method.Finally,based on the non-subsampled shear wave transform-parameter adaptive pulse coupled neural network method,the fracture sensitive parameters and attributes can be fused with multi-source information,and relatively accurate comprehensive characterization results are obtained.This method preserves the detailed information of fracture characterization and eliminates some redundant components,the final comprehensive seismic characterization results of fractured reservoirs can be more accurate.