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.