Abstract

Shear-wave attenuation and velocity have been measured in the kiloHertz frequency range at temperatures varying from -80 degrees C to 80 degrees C in a sample of Berea sandstone partially saturated with glycerol. I investigated 7 saturation states ranging from 0 to 62 percent of the pore space. Plots of attenuation versus temperature show squirt and viscous shear peaks, even at low saturation. Their amplitudes and half-widths increase with increasing saturation. The maxima of the peaks progressively move to higher temperatures (about 4 degrees C for viscous shear peak and 30 degrees C for squirt peak) with increasing saturation from 7 to 62 percent. The velocity dispersion between -80 degrees C and 80 degrees C progressively increases from 700 to 1200 m/s with increasing saturation from 7 to 62 percent.By introducing the crack saturation parameter, a simple viscoelastic model based on O'Connell and Budiansky and using a Cole-Cole distribution of cracks, is proposed for calculating the shear modulus in partially saturated rocks. This model partially interprets the experimental data.

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