Simple Models for Underdamped Slug Tests in High Permeability Aquifers

Accurate hydraulic conductivity values are necessary for understanding groundwater flow. Methods for estimating hydraulic conductivity show limitations because measured values vary several orders of magnitude in high permeability aquifers. Slug tests, while cost and time efficient, result in values lower than expected. It is proposed that underdamped behavior of water in a well is similar to mass on a damped spring; hence, models constructed to simulate behavior independent of aquifer effects might replicate some tests. The Poiseuille and Darcy-Weisbach models, and extensions of these models considering entry/exit effects, are applied to an aquifer-free laboratory test, and real wells. Aquifer-free laboratory tests are modeled well using both Poiseuille and Darcy-Weisbach models with entry/exit effects. The Poiseuille model for wells does not agree with observed data, possibly because of high Reynolds numbers. The Darcy-Weisbach model does agree with well data significantly better, although the friction factor relies on a single Reynolds number