Knowing the intrinsic elastic anisotropy properties of the reservoir rocks in enhanced geothermal systems is important in stress field inversion and accurate determination of induced microseismic events. Here, we perform lab experiments to measure P- and S-wave velocities to determine the seismic anisotropy using a foliated and a non-foliated granite rock. We measure both velocities and attenuations with increasing confining pressures from 5 to 50 MPa in ultrasonic frequency bands. As the confining pressure increases, the results demonstrate significant increases in P-wave velocity and S-wave velocity for both foliated and non-foliated granite. In the case of foliated granite, the P-wave velocity increases by more than 22%, while the S-wave velocity increases by more than 13%. Meanwhile, the non-foliated granite exhibits an increase of over 18% in P-wave velocity and a more than 25% increase in S-wave velocity due to the same pressure increment.

This content is only available via PDF.
You can access this article if you purchase or spend a download.