Premium
Velocity and attenuation in sandstone at elevated temperatures and pressures
Author(s) -
Jones Terry,
Nur Amos
Publication year - 1983
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl010i002p00140
Subject(s) - attenuation , softening , geology , pore water pressure , shear (geology) , dissipation , viscosity , relaxation (psychology) , atmospheric temperature range , thermal , mineralogy , materials science , mechanics , geotechnical engineering , thermodynamics , composite material , petrology , optics , physics , psychology , social psychology
New measurements of seismic velocity and attenuation have been made in the kiloHertz frequency range to temperatures of 120°C, confining and pore pressure to 200 bars in Berea sandstone. With increasing temperature, shear velocity and attenuation decrease at all pressures in a fully saturated rock. The data suggest that thermal relaxation is not a significant loss mechanism under these conditions. We propose that dissipation is controlled by a viscous fluid flow mechanism, in which a sharp frequency peak in attenuation is shifted from 2kHz at room temperature to 8 kHz at 120°C as the pore fluid viscosity is decreased with increasing temperature. However, the velocity decrease is too great to be accounted for by a change of relaxation times. A non‐dispersive temperature softening in shear may control the velocities.