Abstract: Studies on the acoustic characteristics of rocks are the groundwork for geomechanical logging and the evaluation of reservoir properties, and the acoustic properties of shale are especially affected by its stratification and hydration. Hence, we have performed ultrasonic transmission tests on stratified shale with varying levels of hydration, to study the characteristics of the soundwaves' transmission speed and attenuation of energy under these circumstances. We have found that as the stratification angle increases, the P- and S-wave velocities and the P-to-S-wave velocity ratio decrease, while the attenuation coefficients of the P- and S-waves increase. Furthermore, as hydration increases, the velocity of P-waves first increase, then decrease at higher levels of hydration, whereas its attenuation coefficients are inversely correlated. The velocity of S-waves decreases slightly at lower levels of hydration, and basically remains unchanged at higher levels of hydration, while its attenuation coefficients are not significantly affected by hydration. A comparative analysis of the normalized results demonstrates that stratification angles have a greater effect on P- and S-wave velocities than hydration.

Key words: shale, water content, stratification angle, acoustic characteristics, normalization, experiment