Frequency-dependent reflection properties of diffusive-viscous waves

Based on the diffusive-viscous theory, we have investigated characteristics of frequency-dependent reflection coefficient as a function of incident angle at an interface between two dispersive media or between a nondispersive medium and a dispersive medium. We observe that significant attenuation occurs in fluid-saturated layer because of high velocity dispersion and the attenuation in gas- and oil-saturated rocks is larger than that of water-saturated rocks. Furthermore, the results show that reflection coefficients of fluid-saturated layers vary significantly with frequency. Three cases are considered and show that 1) the amplitude and phase angle of reflection coefficient from an interface between air- and water-saturated medium change insignificantly with frequency because of its lower dispersion. 2) the amplitude of reflection coefficient at an interface between air- and oil-saturated medium increases toward higher frequencies because of high dispersion when the incident angle is less than 50°, which agrees with the low-frequency dim-out response, and the phase angle increases with incidence angle and decreases with increasing frequency. 3) The amplitude of reflection coefficient at an interface between oil- and water-saturated medium increases toward lower frequencies because of significant dispersion when the incident angle is less than 50°, which coincides with the low-frequency bright-spot response, and the phase angle is always negative and varies complicatedly with frequency.