Seismic wave attenuation and dispersion in fluid-saturated rocks: A unified poroviscoelastic model incorporating squirt flow and viscoelasticity into Biot’s equations

ABSTRACT Seismic wave propagation in fluid-saturated rocks exhibits complex attenuation and dispersion characteristics across a wide frequency range, which are influenced by various mechanisms of energy dissipation. An integrated poroviscoelastic model that combines three primary attenuation processes was introduced: Biot global flow, squirt flow, and the intrinsic viscoelasticity of the solid skeleton. An integrated time-domain Biot-crack approach was developed by incorporating a 1D squirt flow representation within Biot’s framework. The squirt flow mechanism was described using a generalized Zener model, which approximates its core term through a rational function, with coefficients optimized via a genetic algorithm. Furthermore, the model was extended to the poroviscoelastic medium by also incorporating the standard linear solid (Zener) viscoelastic model to account for intrinsic frame losses. This unified methodology effectively identified three distinct attenuation peaks across the frequency spectrum, each corresponding to a specific mechanism: intrinsic frame viscoelasticity at low frequencies, squirt flow at intermediate frequencies, and Biot’s global flow at higher frequencies. The simulations in heterogeneous media demonstrated significant wave attenuation and velocity dispersion effects. This integrated framework enhanced the characterization of wave behavior in fluid-saturated rocks, with important implications for reservoir characterization and seismic interpretation.