ABSTRACT

The Miocene Oakville Formation is a major Gulf Coast freswater aquifer and uranium host. The impact of long-term pumping during the restoration phase of leach-mining depends upon the efficiency of water quality improvement methods, characteristics of the aquifer, and meteorological fluctuations affecting recharge. Newly acquired data from this industry has improved understanding of fluid migration in a fluvial depositional system.

Development of the in situ leach-mining industry has added vast amounts of subsurface hydrogeological data obtained from the operation of an extensive network of wells. Both surface and subsurface data were combined in this investigation which included analysis and interpretation of outcrop samples, uranium drill logs, cross-sections loaned by companies, pumping test data, water well data furnished by the Texas Department of Water Resources, and geological and soils maps. This information was incorporated into the U.S. Geological Survey three-dimensional finite-difference computer model to predict ground water behavior in a heterogeneous and anisotropic aquifer. Results indicate leakage through confining beds and communication across growth faults, suggesting that the Oakville is a complex aquifer system rather than a simple confined aquifer.

Understanding the development of intricate flow paths and controlled movement of fluids through designed and controlled systems may improve methods of shallow water flooding of petroleum reservoirs as well as management of water resources.