Electrical Resistivity Imaging
Electrical resistivity imaging (ERI) provides a good method to understand the distribution
of fluids and rock properties in the subsurface environment especially in the presence
of fractures or karst features. The method allows an electrical image to be created
with a resolution of half the distance between electrodes, which typically provides
a meter-scale dataset that can be utilized to evaluate heterogeneity and fluid distribution.
Improvements in sensitivity generated by the Halihan/Fenstemaker method allow greater
differentiation of these signatures. In a field setting, this will result in a two-dimensional
mapping of subsurface electrical properties for each dataset, which will be used to
interpret groundwater movement in a complex mantled karst with applied manures.As
part of cooperative research, Oklahoma State University (OSU) designed and conducted
ERI imaging experiments and will integrate ERI data with well and other site data
to provide an understanding of the subsurface distribution of flowpaths at a background
and manure study site. Dr. Todd Halihan and his graduate research assistant (OSU)
travelled to the sites to conduct the imaging and data collection.
The work was conducted in late December, 2014 and data quality is anticipated to be high due to the geologic setting lacking metallic infrastructure. The resistivity structure of the site will be evaluated with OSU working with UA and Aestus to ensure proper integration of the ERI acquisition location and scale with the UA well and soil sampling protocols. Data acquired during the ERI analysis of Fields 5a and 12 will be processed and analyzed by OSU researchers during the first quarter of 2015 and results will be made available in the next Quarterly Report, due April 15, 2015.