Analysis Of Multi-component Frequency-dependent AVO Response Based On Rock Physics Model

Seismic wave propagation in the rocks usually appear velocity dispersion and attenuation,but the traditional AVO technology is based on the assumption that reflection amplitude is just a function of the offset without taking the frequency into consideration.So in this paper,the frequency-dependent AVO analysis based on the theory of White’s patchy saturated model and Zoeppritz equation of attenuation media is more close to the actual situation of the underground.It is generally accepted that in the seismic frequency band the major cause of attenuation in porous media is wave induced fluid flow of mesoscopic scale,and many geophysicists have been studied the attenuation mechanism and proposed a variety of equivalent medium model to simulate the complex situation of the underground.This paper discusses some classic models such as Gassmann theory,Biot theory,BISQ model and patchy saturated model.And also the thinly periodic layered patchy saturated model’s calculation method was improved,by joining the calculation of the porosity influence permeability and matrix modulus,considering different buried depths of reservoir’s pressure and temperature will influence the gas properties.Three different models are taken into consideration to analyze the dispersion and attenuation caused by porosity and gas saturation,in turn impacting on AVO attributes.The frequency dependent AVO inversion method which is based on Smith & Gidlow approximation’s first order Taylor expansion was studied,and it was tested well in the real data application.The AVO attributes are sensitive to frequency and gas saturation so we proposed a frequency-dependent cross-plot template to distinguish the gas saturation.