Horizontal ethanol floods in clean, uniform, and layered sand packs under confined conditions

Abstract

Six ethanol floods were conducted in clean, uniform, and layered crystal silica sands to establish a baseline performance and sweep efficiency of ethanol flooding in clean sand packs under confined conditions. Flow experiments were conducted with horizontal darcy velocities of the order of 4 to 12 m d−1. At darcy velocities less than 5 m d−1 the time required for the propagating ethanol front to reach its stable configuration compared well with predictions based on a model of gravity segregation of miscible liquids in a no‐flow domain. The stabilized angles of the advancing ethanol front in uniform fine sand packs varied between 45° and 77°, depending on the darcy velocity. Poor agreement was obtained between the measured inclination angles and predictions based on several previously published sharp interface models that exclude the effects of dispersion. However, the measured inclination angles compare well with the angles predicted by the method of Hawthorne [1960] when the method is modified to account for the peak viscosity of the ethanol‐water system. Finally, in layered sand packs using coarse and fine sands, gravity override of the ethanol was greatly exaggerated because of anisotropy introduced by the layering.