Fluid saturation strongly influences seismic wave propagation in reservoir rocks and is therefore important for hydrocarbon characterization, time-lapse monitoring, and geological CO₂ storage. This review examines how fluid type, saturation level and distribution, pore structure, permeability, effective pressure, and frequency control seismic velocity, attenuation, and dispersion. P-wave velocity is generally more sensitive to fluid substitution than S-wave velocity because pore fluids directly modify the saturated bulk modulus. Under partial saturation, however, average saturation alone cannot uniquely determine seismic response because heterogeneous and patchy fluid distributions generate spatial pore-pressure contrasts. Wave-induced fluid flow driven by these contrasts causes viscous energy dissipation and seismic attenuation, while incomplete pressure equilibration produces frequency-dependent velocity dispersion. Experimental, theoretical, and numerical studies show that the characteristic response is strongly controlled by saturation geometry, fluid properties, permeability, and measurement frequency. Joint interpretation of velocity, attenuation, and dispersion therefore provides a more complete framework for reservoir-fluid characterization than velocity alone. Future advances require broadband measurements, three-dimensional fluid imaging, digital rock physics, and coupled multiphase-flow and poroelastic modeling to improve quantitative saturation estimation from laboratory to field scales.

Iftekhar Ahmed Shakib,"A Review on Effects of Fluid Saturation on Seismic Velocity, Attenuation, and Dispersion in Reservoir Rocks" International Journal of Advanced Multidisciplinary Research and Educational Development, V2(5): Page(80-94) September - October 2026. ISSN: 3107-6513. www.ijamred.com. Published by Scientific and Academic Research Publishing.