Dispersion characteristics of seismic wave reflection and transmission in porous media strata via the improved Biot model

Abstract

Seismic exploration is a key technique for investigating subsurface structures, with reflected and transmitted waves carrying vital geological information. To improve imaging accuracy in complex fluid-bearing reservoirs, the traditional Zoeppritz equations are modified by explicitly introducing fluid factors and Poisson's ratios, enabling a more accurate characterization of the relationships among rock elasticity, wave velocity, and fluid properties. Building on this, the Biot model is extended via skeleton viscoelastic eigenstructure theory and evolving state variables to incorporate multiple energy dissipation mechanisms, thereby enhancing the simulation of complex wavefield responses in porous media. The proposed approach is applied to the Longmaxi shale reservoir in Hubei Province, China, through numerical simulations and parameter sensitivity analyses. The results show that in the 0.1–100 Hz low-frequency range, the improved Biot model agrees well with the experimental data, effectively capturing wave speed dispersion and energy dissipation characteristics. Compared with the classical model, the enhanced version more accurately reflects the frequency-dependent behavior of seismic wave reflection and transmission coefficients and is more sensitive to changes in incidence angle. Further analysis reveals that key reservoir parameters—such as fluid saturation, fluid type, and porosity—significantly influence wave propagation characteristics, especially in the high-frequency range, where nonlinear modulation effects on the wavefield become more pronounced. These findings demonstrate the effectiveness and applicability of the proposed method in improving reservoir identification and seismic wavefield characterization.