ABSTRACT

In the past few decades, great attention has been focused on uncovering the physics of seismic wave attenuation in fluid-saturated rocks. However, the relationship among many variables affecting attenuation is still not completely clear. For instance, although the role of strain in enhancing friction dissipation is relatively well known for dry rocks, it remains unclear how and how much it affects attenuation in fluid-saturated rocks. We experimentally measured attenuation in the extensional mode in Berea sandstone at strains between 7.8×107 and 1.9×105, and at frequencies in the seismic bandwidth (1–100 Hz). These strains were similar to those typically observed in seismic exploration (106). We also measured the transient fluid pressure caused when a stepwise stress was applied resulting in such strains. For the studied strain range, our results indicated that: (1) the overall attenuation in dry Berea sandstone increased linearly with strain, (2) the frequency-dependent component of attenuation, which was associated with fluid saturation, was approximately insensitive to strain, and (3) the overall attenuation can be considered as a sum of a frequency-independent and a frequency-dependent components.

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