Simulation of well LNAPL thickness and LNAPL recovery with horizontal wells.

摘要

A method of simulating horizontal and vertical wells with fluid stratification was incorporated into a three-dimensional, multi-phase, multi-component finite difference model for subsurface flow and transport. Hypothetical field-scale LNAPL contamination and recovery cases were assumed and modelled, to examine LNAPL volume estimation and horizontal well recoverability.; The effects of water table fluctuations, soil and fluid properties on LNAPL volume estimation from well fluid levels were investigated considering hysteresis and entrapment. Using analytical models could result in an underestimation by up to 95% in complicated field conditions. Air entrapment, especially in the organic phase, is likely an important factor affecting fluid distribution prediction in the soil. An optimally designed horizontal recovery well outperformed a series of vertical wells with 20--45% higher ultimate recovery efficiencies for the LNAPL contamination conditions considered in this study. However, a series of vertical wells could be better for coarse-grained aquifers, due to lower water treatment costs.