The Frequency (or Time) -Temperature Equivalence of Relaxation in Saturated Rocks |
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Authors: | Daoying Xi Xiaoyan Liu Chengyuan Zhang |
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Institution: | (1) Department of Earth and Space Science, University of Science and Technology of China, Hefei, 230026;(2) Advanced Centre for Earth Science and Astronomy, University of Science and Technology of China, Third World Academy of Science, |
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Abstract: | Laboratory data on dry and saturated rocks show that pore fluid has the most important effect on rock attenuation. It is known
that viscous and inertial coupling between the frame of a porous rock and its pore fluid dissipates seismic energy by conversion
to heat and hence cause attenuation. We show that attenuation peaks, in saturated rock have the same property as that of typical
thermally activated relaxations. In the frequency domain, a plot of attenuation versus frequency shows an obvious systematic
shift to higher frequencies with increasing temperatures. Similarly, the attenuation versus temperature curve moves to higher
temperature with increasing frequencies. The attenuation peaks are somewhat broader than that for a Zener relaxation. A Cole-Cole
distribution of relaxation times closely matches the attenuations. This behavior can be explained theoretically by local flow
mechanisms. |
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Keywords: | Attenuation low frequency time-temperature equivalence pore fluid viscosity |
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