Regional and local-scale geologic, geophysical and hydrogeologic studies will be performed to address two primary objectives:
Hydrogeologic controls on ground-water flow and the volume of water stored in aquifers will be examined by
- Evaluating regional geologic influences on ground-water flow
Three-dimensional morphology of the flow system will be displayed through a combination of geologic map data, hydrogeologic-unit thickness data, and geologic cross sections supported by geophysical data and models. Geologic information on the major structural elements within the study area will be compiled. Representative cross sections will be drawn to display the structure of the region and to assist in volumetric calculations.
- Performing geophysical studies
Geophysical methods will be used to characterize the geologic framework influencing ground-water resources in the study area. Regional gravity, magnetic, and electrical methods will be used to define major basin-bounding and intra-basin faults, the thickness of the cenozoic geologic units, infer the subsurface three-dimensional geometry of the pre-cenozoic basement, and determine the thickness of the carbonate section. The geophysical data will be used to develop two- and three-dimensional geologic framework models of the subsurface for each of the basins in the study area.
- Compiling and evaluating data for oil and gas wells
Data from oil and gas wells has been used previously to estimate transmissivity from drill-stem tests at 24 oil and gas wells in the study area. The estimates will be updated with new well data and will also include estimates of storage properties for carbonate-rock aquifers using selected geophysical borehole logs. Maps of major Paleozoic carbonate-rock and Cenozoic basin-fill aquifers showing significant thickness and lithologic and facies variations linked to porosity and permeability of the aquifers will be developed.
