Effect of Dispersion, Gravitational Segregation, and Formation Stratification on the Recovery of Freshwater Stored in Saline Aquifers

Abstract

A calculation procedure has been devised, using existing analytical and empirical relationships, to predict mixing and gravitational segregation in a horizontal radial flow system. The procedure yields results that show excellent agreement with experimental results obtained with a three‐dimensional laboratory flow model in which both mixing and gravitational segregation occur simultaneously. Thus validated, the calculation procedure was applied to the prediction of the efficiency with which freshwater stored in saline aquifers might be recovered for later use. Low aquifer water salinity, low formation permeability, and low formation thickness lead to the most favorable recoveries. The calculation procedure indicates that recovery efficiency improves with the number of injection‐production cycles, thus suggesting that even for unfavorable conditions the process might become feasible on a long‐term basis. Graphical presentations show the relative importance of several pertinent variables including formation stratification.