2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 18
Presentation Time: 1:30 PM-5:30 PM


PANTEA, Micahel P.1, COLE, James C.2 and FAITH, Jason R.1, (1)USGS, MS 980, PO Box 25046, Denver Federal Center, Denver, CO 80225, (2)U.S. Geol Survey, MS 980, Box 25046, Denver Federal Center, Denver, CO 80225, mpantea@usgs.gov

This presentation displays an interactive 3-D viewer for a three-dimensional faulted stratigraphic model representing the geologic framework of the Edwards aquifer system in the area of San Antonio, northern Bexar County, Texas. The viewer allows users to manipulate the model volume in 3-D space by rotating, zooming, and panning in real-time. The model allows cross-sections perpendicular to the X, Y, or Z-axes at pre-set spacings or positions selected by the user. Model hydrostratigraphic layers may be set to “display” or “not display” so that tops of stratigraphic units may be examined in detail, and fault offsets of particular units may be displayed and analyzed. Fault blocks may be identified and set to “display” or “not display” allowing the user to explore fault structure in detailed 3-D renderings. Tools are provided to display any of the drillhole and outcrop data used to generate this 3-D geologic model. Scattered drillhole data used to generate hydrostratigraphic horizons may be displayed, or all of the data may be shown for all drillholes. All data points displayed within the model can be queried to show the X, Y, and Z coordinates along with well or site identifier. The 3-D model is based on mapped geologic relationships that reflect the complex structures of the Balcones fault zone, and on interpretations of about 40 principal wells and qualified data from numerous other wells. The model depicts three major and eight subsidiary hydrostratigraphic subdivisions of the Edwards aquifer, as well as intersections of numerous faults in the subsurface and their impacts on the continuity of the Edwards aquifer units. The model allows for detailed examination of the extent of fault dislocation and the degree of reduction in effective aquifer cross-sectional area across faults. Users may explore interactions of en-echelon fault strands and flexed connecting relay ramps and visualize lateral connections between hydrostratigraphic units of relatively high and low permeability across individual faults.