Modeling wells in variably saturated soil with wellbore fluid gravity segregation

Abstract A method is presented for incorporating the dynamics of a well with finite wellbore volume into finite difference models of air and water flow in variably saturated porous media. The method is based on the assumption of fluid gravity segregation with water accumulation at the bottom of the well. The method accurately accounts for changing water levels in the well and the corresponding changes in air and water storage in the wellbore. The method was added to a three-dimensional finite difference model for multiphase flow and transport and tested against three-dimensional pilot scale experiments of water injection into initially unsaturated soil. Well water levels and soil moisture contents monitored during the course of the experiments compared well with the model predictions.

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