Calibrating surface NMR hydraulic conductivity estimates using logging NMR and direct hydraulic conductivity measurements

摘要

Assessment of aquifer flow properties such as hydraulic conductivity (K) is critical for locating new wells and informing investigations of contaminant transport. Often direct hydrologic measurements are used to estimate K, however geophysical methods are emerging as a viable alternative for estimating K either by using existing wells or through entirely noninvasive methods. Nuclear magnetic resonance (NMR) has particularly high potential in this field because the measurement is directly sensitive to water content and is also related to properties of the pore space. Here we demonstrate the transformation from surface NMR T_2* to hydraulic conductivity values. We also explore the possibility of making a calibration at one location and then using that calibration at nearby locations for detailed site characterization. Our results demonstrate this application in two sites with contrasting hydrologic properties and show that a site-specific calibration can result in NMR estimates of K within an order of magnitude of traditional direct K measurements.