Seismic velocities of halite salt: Anisotropy, heterogeneity, dispersion, temperature, and pressure effects

Abstract

We have made various experimental investigations on rock-physics properties of the halite salt coming from a salt dome in the U.S. Gulf Coast Basin. The effect of crystal defects and intercrystal cracks on the P-wave velocity of the halite salt sample can be mitigated after high-pressure annealing. The temperature effect on seismic velocities of halite salt is dominant relative to the stress effect. Azimuthal anisotropy is not observed on the halite salt samples. We have observed that the velocity variations in different directions were mostly caused by the crystal-scale heterogeneity. For the salt structures primarily made of creep-deformed halite, the effect of seismic velocity anisotropy might be negligible for seismic exploration. No significant dispersion of seismic velocities was observed from the low-frequency measurement. Our measurements supply basic information for seismic velocity model building that may help to improve seismic imaging of salt structures.