Measurement of Dielectric Properties (MHz–MHz) of Sedimentary Rocks

The  dielectric  property  is  a  useful  parameter that  can  be used to infer other properties of porous media such as water saturation, permeability, etc. The dielectric properties (mHz to MHz) of isotropic porous media have been extensively studied.  However,  related  studies  are  very  rare  for anisotropic porous media. In this study, we have measured the directional dielectric spectra of two sedimentary rocks (one  Bakken  shale  sample  and  one  Lyons  sandstone sample)  using  the  combination  of  2-  and  4-  electrode methods in the frequency range between 10^-3 and 10⁷ Hz. It is shown that the dielectric constant of these two samples generally  increases  as  the  frequency  decreases.  This  is because,  as  the  frequency  decreases,  more  polarization mechanisms start to  contribute  to  the measured  dielectric constant. It is also shown that the dielectric anisotropy in these  samples  decreases  as  the  frequency  increases, indicating  that  different  polarization  mechanisms  induce different degrees of dielectric anisotropy.