Date of Award

1974

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Abstract

The computational procedure presented in this disser­ tation should enable the practicing engineer to design well fields for the storage of fresh water in horizontal saline aquifers in which there is no pre-existing ground-water movement. The recovery efficiency of the injection/storage/ retrieval process can now be reliably computed, thus making possible an economic analysis of the process in any speci­ fied area. An economic comparison of the storage of ap­ proximately one billion gallons in a saline aquifer that underlies the New Orleans area was made with the present most feasible alternate--steel tanks. The results favored the saline aquifer storage project by a factor of more than 50 to 1. The validity of the computational procedure was de­ termined by comparing recovery efficiencies obtained from a laboratory-size miniature aquifer (miniaquifer) with re­ covery efficiencies predicted by the computational pro­ cedure. The computational procedure predicted the experi­ mental data within 10 percent for multiple well systems. The predicted recovery efficiencies were invariably lower than the experimentally determined recovery efficiencies. The aquifer parameters that must be determined before the computational procedure can be used are thickness, permeability, porosity, storativ1ty, longitudinal disper­ sivity coefficient, and viscosity and density of the native fluid. Of the parameters mentioned above the longitudinal dispersivity coefficient is the most difficult to obtain. The procedure used in this investigation to determine the longitudinal dispersivity coefficient for the miniaquifer can be readily adapted to field use. In addition to the aquifer parameters, the well field configuration, the operation schedule of the field, the volume of fresh water to be injected, injection rates, probable duration of storage, production rates, and frac­ ture pressure of the upper confining bed must be known in order to make an economic analysis. When fresh water is injected into a horizontal, homogeneous, saline aquifer which has no pre-existing ground-water movement, the two most important factors which determine the amount of usable water that can be recovered are: (1) mixing of the two fluids due to molecular diffu­ sion and convective dispersion, and (2) gravitational seg­ regation of the two fluids due to density difference.

Pages

152

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