Hydraulic Conductivity from Nuclear Magnetic Resonance Logs in Sediments with Elevated Magnetic Susceptibilities.

This study examined the application of slim-hole nuclear magnetic resonance (NMR) tools to estimate hydraulic conductivity (K ) in an unconsolidated aquifer that contains a range of grain sizes (silt to gravel) and high and variable magnetic susceptibilities (MS) (10 to 10 SI). A K calibration dataset was acquired at 1-m intervals in three fully screened wells, and compared to K estimates using the Schlumberger-Doll research (SDR) equation with published empirical constants developed from previous studies in unconsolidated sediments. While K using published constants was within an order of magnitude of K, the agreement, overprediction, or underprediction of K varied with the MS distribution in each well.

Permeability profiles in granular aquifers using flowmeters in direct-push wells.

Numerical hydrogeological models should ideally be based on the spatial distribution of hydraulic conductivity (K), a property rarely defined on the basis of sufficient data due to the lack of efficient characterization methods. Electromagnetic borehole flowmeter measurements during pumping in uncased wells can effectively provide a continuous vertical distribution of K in consolidated rocks. However, relatively few studies have used the flowmeter in screened wells penetrating unconsolidated aquifers, and tests conducted in gravel-packed wells have shown that flowmeter data may yield misleading results.

Comparative study of methods for WHPA delineation.

Human activities, whether agricultural, industrial, commercial, or domestic, can contribute to ground water quality deterioration. In order to protect the ground water exploited by a production well, it is essential to develop a good knowledge of the flow system and to adequately delineate the area surrounding the well within which potential contamination sources should be managed. Many methods have been developed to delineate such a wellhead protection area (WHPA).