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- Title
Frequency-dependent reflections in elastic diffusive-viscous media.
- Authors
Zhao, Haixia; Gao, Jinghuai; Peng, Jigen
- Abstract
Amplitude variation with offset/angle of incidence (AVO/AVA) analysis is essential for hydrocarbon detection and reservoir characterization. Frequency-dependent AVO analysis plays an important role in seismic interpretation especially for the low-frequency seismic anomalies related to hydrocarbon reservoir. The diffusive-viscous model is used to explain these anomalies, but it does not consider the shear effects of rocks. In this work, we firstly extend the diffusive-viscous model to elastic case based on the mechanisms in a macroscopic porous medium. The elastic diffusive-viscous model describes attenuation of compressional and shear waves in a fluid-saturated medium and it reduces to the classic elastic wave equation in a special case. Then, we investigate the properties of reflection/transmission coefficients at an interface between two different elastic diffusive-viscous media. The reflection/transmission coefficients not only relate to the parameters of the media but also depend on the frequency. Two examples are given to analyze the dependence of the reflection/transmission coefficients on the frequency and incident angle at interfaces between gas-saturated sandstone and brine-saturated shale and between brine-saturated shale and oil-saturated sandstone. The results show that the magnitudes and phase angles of the reflection/transmission coefficients are significantly dependent on the frequency at lower frequency (<20 Hz). Finally, we apply the frequency-dependent reflection/transmission coefficients to the extended reflectivity method to model the propagation of the elastic diffusive-viscous wave in a layered medium. The modeling results show that the diffusive-viscous wave has strong amplitude attenuation and phase shift compared with those of elastic wave when the wave propagates across fluid-saturated layers.
- Publication
Journal of Geophysics & Engineering, 2018, Vol 15, Issue 5, p1
- ISSN
1742-2132
- Publication type
Article
- DOI
10.1088/1742-2140/aac038