Seismic Wave Field Simulation And AVO Attribute Analysis Of Multiphase Medium

In the seismic exploration, the stratum is usually treated as the single-phase medium. Practically, oil-stratum is the biphase or multi-phase medium, which is the combination of solid and fluid, so, we need to study the elastic theory of the multi-phase media to meet the demand of the exploration of oil and gas hydrate resources.The thesis presents the staggered-grid high-order difference method of the one-order elastic wave equation. Through discussing and analyzing of the stability condition and influencing factor of numerical dispersion, we conclude that the simulating method can improve computation accuracy and efficiency. The flux-corrected transport (FCT) method can eliminate the dispersion efficiently. By analyzing the one order elastic wave equations, we obtained the absorptive boundary condition which can absorb man-made boundary reflection efficiently. We proved the double compressional wave phenomena from the Biot wave equation and we modeling the waves in the saturated fluid biphase media. We find that the phase of slow compressional wave is reverse in solid and fluid respectively, and the amplitude of slow compressional wave is higher in fluid than which in solid.By comparing the different formulas of P-P reflection coefficient we summarize the characteristics and applying conditions of the approximative formulas.Velocity formula of the composition elastic porous media is deduced, which is based on wave physics. The relationship among elastic parameters of porous media is researched. We choose the different formula to model the AVO response of the stratum which has different porosity and saturation. We find that a little free gas saturation in the underlying stratum of gas hydrate accumulation can bring great influence of the AVO character, and it changes little as the saturation increase. The sensitivity of different AVO attributes are discussed and compared based on multiphase medium contains different fluid.