The presence of partially frozen liquid in the pore spaces of porous materials has significant effects on elastic wave propagation. Although the characterization of partially frozen systems using velocity information has been well developed, application of the attenuation information is limited because the attenuation mechanisms in partially frozen systems are poorly understood. We have conducted ultrasonic wave transmission measurements with changing temperatures from 0°C to $-15°\mathrm{C}$ to estimate the effect of partially frozen liquids grown in unconsolidated (unconsolidated sediment) and consolidated (synthetic porous rock) materials on the velocity and attenuation of P- and S-waves. Our experimental results determined that the existence of partially frozen liquid in the unconsolidated and consolidated materials increases the velocity and attenuation for temperatures of 0°C to around the freezing point (i.e., $-3°\mathrm{C}$), thus experimentally validating the unintuitive observations of high velocity and high attenuation. We interpreted the differences in velocity-versus-temperature curves as both the difference in inherent stiffness between the matrix of the consolidated material and the ice frame of the partially frozen unconsolidated material and the microscale ice distribution in pore spaces. We have also attributed the difference in the attenuation-versus-temperature curves in the unconsolidated and consolidated materials between the P- and S-waves to the difference of attenuation mechanism between the P- and S-waves. Our findings can be used for interpreting the velocity and attenuation results from the sonic logging measurements.

Three-dimensional vertical seismic profiling data acquired from an oilfield located in Abu Dhabi, United Arab Emirates, were used to obtain a high-resolution multioffset azimuthal estimate of compressional seismic wave attenuation. On the basis of the assumption that the fracture strike corresponds to the azimuthal direction φ0 at which the attenuation is minimized, fracture orientations were obtained in three reservoir units. Two approaches were used to determine φ0: first from the variation of the absolute attenuation Q−1 with the azimuth and second from the variation of the relative attenuation ΔQ−1 with the azimuth. The rose diagrams of φ0 estimated from the Q−1 variation indicated better agreement with those showing the strikes of open and cemented fractures obtained from core interpretation than with either of those showing the two types of fractures separately. However, the rose diagrams of φ0 estimated from the variation of ΔQ−1 were more similar to those showing the strikes of open fractures obtained from core and Fullbore Formation Microimager data. This observation can be explained by the fact that in the first approach, all types of fractures contribute to the scattering and fluid-related mechanisms of Q−1. However, in the second approach, φ0 is obtained from a least-squares fitting of the variation of ΔQ−1 with the azimuth, which is based on the squirt flow mechanism that is caused by the movement of fluid between grain pores and fractures. Therefore, a comparison of the orientations obtained using these two approaches can be an efficient way to separately determine the orientations of open and cemented fractures.