Effects of heterogeneities and anisotropy on sonic and ultrasonic attenuation in rocks

Abstract

We compare the attenuation obtained by the resonant bar technique in the sonic frequency range (3–10 kHz) with that obtained by the pulse transmission technique in the ultrasonic frequency range (500 kHz) on a set of 30 rocks, including sandstones and limestones. The sonic and ultrasonic measurements were performed under high effective pressure on adjacent water‐saturated samples from each rock block. Compressional ultrasonic attenuation was typically larger than extensional sonic attenuation, particularly in limestones. This is attributed to the presence of density heterogeneities, that can be seen on X‐ray scanner imagery. Heterogeneities at the scale of the ultrasonic wavelength produce diffraction of the waves, and as a consequence, high attenuation values. At ultrasonic frequencies, large apparent shear attenuation values, compared to compressional attenuation values, are explained by shear wave splitting.

Ultrasonic velocity and attenuation anisotropy of shales, Whitby, United Kingdom

“…A schematic illustration of the experimental setup is shown in Figure 2. A pulse transmission method (Toksöz et al, 1979;Lucet and Zinszner, 1992) was used to measure the decay of amplitude of the propagating wave in the sample. This technique measures attenuation relative to a reference sample, which has very low attenuation.…”

Contact micromechanics in granular media with clay

“…Kiister and Toksoz (1974a), Kiister and Toksoz (1974b), Plona and Johnston (1981), , Winkler and Murphy (1984), Blair (1990), Lucet and Zinszner (1992) Squirt Fluid Flow Mavko and Nur (I979), Palmer and Traviolia (1981), Bulau et. al, (1984), Dvorkin et.…”

Seismic wave propagation in Kelvin visco-elastic VTI media

“…Also, both the seismic field observations and lab studies have demonstrated that most sedimentary rocks display long-wavelength anisotropy, so the anisotropy relates closely with visco-elasticity (Lucet and Zinszner, 1992). Visco-elastic anisotropic media has been researched for many years.…”