Fig 1.
Pore-scale numerical model of elastic wave propagation in porous media.
Elliptical pores with different sizes and aspect ratios are arbitrarily orientated and randomly distributed in the matrix. A pulse load is added to one side of the modeling core as a source. The other three sides are low-reflection boundaries. Receiving points are equidistantly located on the center part of the side opposite to the source.
Fig 2.
Effects of elliptical pore distribution on the modeled scattering attenuation.
We calculate 10 models with randomly distributed elliptical pores at the porosity of 8%, 12%, and 16%, respectively. The pore aspect ratio and pore size in these models are constant: ARmod = 0.55, dmod = 3 mm. The modeling frequency is 0.1MHz. The error bar is 5% of the average modeled scattering attenuation coefficient.
Table 1.
Scale factors and parameters used in the numerical modeling.
Fig 3.
The received signals and corresponding frequency spectrums from models with different pore sizes.
Different colors are used to discriminate signals from the reference core and the modeling cores with different pore sizes. The pore aspect ratio and pore number in these models are constant: ARmod = 0.55, N = 300. The source frequency (fmod) is shown at the top of the figure. (a) and (c) are received signals; (b) and (d) are the corresponding frequency spectrums.
Fig 4.
Influence of pore size on the scattering attenuation coefficient.
Data points are from the numerical modeling: triangular points for the source frequency at 0.1MHz, square points for the source frequency at 0.03MHz. The color of data points indicates the ratio of wavelength to pore size. The dotted line and the solid line are fitted by Eq 4 respectively. The pore aspect ratio and pore number in these models are constant: ARmod = 0.55, N = 300.
Fig 5.
The received signals and corresponding frequency spectrums from models with different pore densities.
Different colors are used to discriminate signals from the reference core and the modeling cores with different pore numbers. The modeled domain is fixed, so different pore numbers result in different pore densities. The pore aspect ratio and pore size in these models are constant: ARmod = 0.55, dmod = 3mm.
Fig 6.
Influence of pore density on the scattering attenuation coefficient.
Data points are from the numerical modeling at fmod = 0.1MHz. The solid line is fitted by Eq 13. The pore aspect ratio and pore size in these models are constant: ARmod = 0.55, dmod = 3mm.
Fig 7.
Influence of pore aspect ratio on the scattering attenuation coefficient.
Data points are from the numerical modeling with varying pore aspect ratio at pore number of 300, 800, and 1200 respectively. The solid line is fitted by Eq 14. The pore number, pore size, and source frequency in these models are constant: N = 300, dmod = 3mm, fmod = 0.1MHz. The magenta dashed lines are from Sevosianov and Kachanov [22].
Fig 8.
Influence of porosity on the scattering attenuation coefficient.
Data points are from the numerical modeling at fmod = 0.1MHz. The triangular points are from models with varying pore size. The solid circle points are from models with varying pore number and pore aspect ratio, and the corresponding λ/d is larger than 15. The solid lines are fitted by Eq 15.