Wave Dispersion And Attenuation In Elastic And Viscoelastic Media With Multiphase Flow And Its Applications

The Biot mechanism, Squirt-flow mechanism, viscoelasticity and multiphase floware the most important factors that affect the wave dispersion and attenuation. So it isvery import for the reservior prediction to study their influenc on the wave dispersionand attenuation.Fisrt, high dimensional BISQ model of the partial stress form is given, and thewave propagation equation that the P-wave and S-wave Lame potentials satisfy is givenby performing wave field decomposition on the BISQ model. Based on the Lamepotentials equation, the low frequency approciamtion formula is derived. Furthermorethe BISQ model containing multiphase flow is gained by correcting the charastic squirtlength and its low frequency approcimation formula is also derived to study the wavedispersion and attenuation. Numerical result shows that viscoelasticity affect both thedispersion and the attenuation of the fast P-wave and the S-wave, whereas affect littleon slow P-wave. Permbility affect fast P-wave and slow P-wave greatly but little on theS wave. Gas content in porous system affect greatly on dispersion and attenuation of thefast P-wave, the velocity of S-wave, and has almost no effect on the slow P-wave.Second, the SSM method is given for solving the BISQ model containingmultiphase flow. It eliminates the numerical dispersion effectively under coarse grids,and has quick computation speed. Wave field is simulated with multiphase flowincluded in the porous fluid, which reveals that the fast P wave velocity of the BISQmodel is slower than that of the Biot model, and becomes larger when gas contentincreases.Third, it is derived that the partial different equations which the the P-wave andS-wave Lame potential satisfies at the fluid-solid interface under the coupling action ofBiot mechanism, Squirt-flow mechanism and multiphase flow. Then the relationship ofthe reflection and transmission coefficients at the interface is gived to study theinfluence of incident angle, permeability and the gas content on the relection andrefraction. It is discovered that critical angle of the fast P-wave decreases with gascontent increasing.Finally, in order to verify the validity of the BISQ model containing multiphaseflow, it is applied to inverse synthetic, experimental and real data together with the self-adaptive hybrid genetic algorithm. Inversion results show the self-adaptive hybridgeneric algorithm is a effective method to inverse more accurate result very quickly, theviscoelastic BISQ model containing multiphase flow is effective to depict the dispersionand attenuation at the low frequency range, and the low frequency approcimationvelocity formula is effective to predict accurate reservoir parameter, and improve theconputation speed greatly.