Laboratory measurement of P-wave anisotropy in shales with laser ultrasonics

We propose a new method to measure the P-wave anisotropy in core shales with laser ultrasonics. The measured velocities show significant P-wave velocity and attenuation anisotropy. We estimate within 1^◦ the fast and slow wave directions in two shales, and assess if the direction of the symmetry axis aligns with the sample layering coordinate system. The laser system is more sensitive to the shale anisotropy than data acquired with transducers as the latter averages wave energy over a greater area. c₁₃ is estimated by fitting the phase velocity equation to the data as a function of angle, but misfits at angles away from the parallel and normal directions to layering are under investigation.