| Popis: |
Measurements of P‐ and S‐wave attenuation in saturated alundum and Berea sandstone were made under confinement with various pore fluids: water (1 cP, 72 mJ/m2), n‐decane (0.92 cP, 28 mJ/m2), glycerol (1490 cP, 64 mJ/m2), and silicone oil (913 cP, 21 mJ/m2). The results for alundum indicate that attenuation for both P and S waves is controlled by viscosity: Qglycerol−1 > Qoil−1 > Qwater−1 > Qdecane−1. Attenuation in alundum is qualitatively consistent with Biot dissipation and is much less sensitive to confinement, presumably because it is composed of well‐sintered contacts. P‐ and S‐wave attenuation in Berea sandstone is not purely viscosity dependent: Qwater−1 > Qglycerol−1 > Qdecane−1 > Qoil−1. Glycerol at 25 °C has the same viscosity as silicone oil but results in P‐ and S‐wave amplitudes that are 55% and 30%, respectively, smaller than those for silicone oil. This result is not consistent with Biot dissipation but may be explained by differences in surface tension or hydrogen bonding at the contacts b... |
