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

Six ethanol floods were conducted in clean, uniform, and layered crystal si lica sands to establish a baseline performance and sweep efficiency of etha nol flooding in clean sand packs under confined conditions. Flow experiment s 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 p ropagating ethanol front to reach its stable configuration compared well wi th predictions based on a model of gravity segregation of miscible liquids in a no-flow domain. The stabilized angles of the advancing ethanol front i n uniform fine sand packs varied between 45 degrees and 77 degrees, dependi ng on the darcy velocity. Poor agreement was obtained between the measured inclination angles and predictions based on several previously published sh arp interface models that exclude the effects of dispersion. However, the m easured inclination angles compare well with the angles predicted by the me thod of Hawthorne [1960] when the method is modified to account for the pea k viscosity of the ethanol-water system. Finally, in layered sand packs usi ng coarse and fine sands, gravity override of the ethanol was greatly exagg erated because of anisotropy introduced by the layering.