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| | Abstract | | Sonic logging has been widely used for many years to understand physical properties of hydrocarbon reservoirs. When gaseous phase exists in the formation fluid, the compressional waves traveling through the formation could be strongly attenuated due to low bulk modulus of gas in the fluid, while the shear waves are not. For acquiring physical properties of fluid in the formation, Biot physics or poroelastic analysis could be the best method. Among the available technologies, quality factors based on the Biot's theory considers the viscous attenuation induced at the interface between rocks and pore fluids, the intrinsic attenuation caused by the internal friction in the matrix is ignored. In the present study, we investigate how is the viscous attenuation acquired by the attenuation of compressional and shear waves through the evaluation of the reservoir properties based on the quality factor when we consider the intrinsic attenuation. We employ a 2D finite-difference scheme to simulate seismic wave propagation in a poroelastic medium. The intrinsic attenuation is included in our model by using the filter of frequency-independent quality factor (constant-Q).Our results clearly show that the amplitude and phase of the waveforms are strongly affected by the intrinsic attenuation and we could get only viscous attenuation by considering both compressional and shear waves. |
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