Geostatistics, wavelet analysis and high-resolution characterization of subsurface electrical conductivity using direct push profiling and electrical resistivity imaging

The electrical conductivity (EC) distribution north of Wetland 109 at the Saint-Denis National Wildlife Area was characterized in order to investigate the effect of small-scale heterogeneity on larger scale geophysical measurements. Characterization of the heterogeneous EC distribution near Wetland 109 was achieved through an extensive geophysical campaign combining direct push (DP) profiling and electrical resistivity imaging (ERI). The small-scale spatial heterogeneity was characterized in the DP data by using geostatistics and wavelet analysis. Both methods of analysis establish that the small-scale EC distribution at the site can be accurately described as a non-stationary fractional Levy-stable process. Comparison of the ERI results to previous ERI survey results and the DP data revealed evidence of scale inconsistencies related to non-ideal discretization schemes, differences in inversion parameters and uncharacterized sub-scale heterogeneity.; Information garnered from the geostatistical analysis, wavelet analysis and scale comparisons can be used to improve current inversion algorithms as well as simulation, upscaling and downscaling techniques. The direct push EC data and ERI data collected, as well as the results of the stochastic analysis performed on both data sets, provide an extensive body of empirical support for future theoretical and modeling work.