Abstract
Fluid saturated rocks exhibit a dependence of acoustic velocities on frequency, which is called velocity dispersion. For some rocks, e.g. shales, velocity dispersion is rather strong and have to be taken into account when interpreting and comparing data from seismic surveys, sonic logs, and ultrasonic measurements on core plugs in the laboratory. In this work, a newlaboratory technique has been developed that allows the direct measurement of the P-wavemodulus at seismic frequencies from which P-wave velocities can be derived. Together with ultrasonic velocity measurements that are carried out simultaneously, the P-wave velocitydispersion between seismic and ultrasonic frequencies is obtained.