Numerical-modeling of pore structure effects on acoustic attenuation in dry rocks

Based on the elastic wave theory and similarity principle,the pore structure effects on acoustic attenuation coefficient in dry rocks were simulated.The calculation results indicate that the scattering attenuation caused by uniformly random distributed pores is stronger than that of regular distributed pores.When the angle between the pore major axis and the wave propagation direction is randomly valued,the attenuation coefficient is in between the minimum with 0°and maximum with 90°. The attenuation coefficient increases exponentially with the increase of aspect ratio at the same pore density,which is mainly contributed by the increase of absorbing attenuation.The attenuation coefficient increases as apower function as the pore density increases at the same aspect ratio.But the mechanism of attenuation is not the same for different changing patterns of pore density.The absorbing attenuation increases when the pore density increased by more pore numbers.However,the scattering attenuation increases when the pore density increased by larger pore size.These results lay a foundation for pore structure prediction from elastic wave responses.