Relation Between Seismic Velocity and Hydraulic Conductivity at the USGS Fractured Rock Research Site

By Karl J. Ellefsen, Paul A. Hsieh, and Allen M. Shapiro

ABSTRACT

An analysis of velocities, derived from crosswell seismic data collected at the USGS Fractured Rock Research Site, shows that the velocities are related to the hydraulic conductivities of the fractured bedrock. The conductivities are calculated from measurements made with a straddle packer. A histogram of conductivities associated with low velocities (less than 5100 m/s) shows that low velocities are indicative of a wide range of conductivies. In contrast, a histogram of conductivities associated with high velocities (greater than or equal to 5100 m/s) shows that high velocities are indicative of low conductivities. Using these histograms, a frequency distribution of conductivity could be assigned to every point in a seismic velocity tomogram.