Spatial characterization of the hydraulic conductivity using direct-push injection logging

Detailed information on the spatial structure of hydraulic conductivity (K) is important for understanding and predicting groundwater flow and transport. Direct-push injection logging (DPIL) is a promising technology for rapid measurement of K in unconsolidated formations. This technology was used to gain information on the highly heterogeneous aquifer at the Lauswiesen test site in Germany. Using a large body of DPIL and direct-push slug testing measurements, we characterize the structure of K on scales not previously possible. Two new applications of DPIL are put forward: (1) use of raw DPIL measurements of relative conductivity K-r to characterize the spatial distribution of K and (2) transformation of K-r measurements to K values based on their statistical moments. The DPIL results are compatible to those obtained using more conventional methodologies. The main achievement of the methodology is the possibility to delineate deterministic aquifer subunits as well as the identification of the statistical parameters of the log conductivity for each subunit. In particular, the horizontal integral scale I, a parameter affecting solute transport, is difficult and costly to identify using other approaches. Nevertheless, further studies are needed to clarify questions on low K-r measurements and the nature of the relationship between K-r and K.