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Indicator Geostatistical Approach to Reconstruct Geological Architecture of the Baton Rouge Aquifer-fault System, Louisiana

Ahmed Elshall, Jeffrey Hanor, and Frank Tsai
[email protected]

The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana, is characterized by a strongly binary heterogeneity of sandy units and mudstones as pervious and impervious hydrofacies. Two distinct east-west trending geologic faults, the Baton Rouge fault and the Denham Springs-Scotlandville fault, cut across East Baton Rouge Parish. The Baton Rouge fault is a low-permeability fault that historically separates a sequence of freshwater aquifers north of the fault from brackish aquifers south of the fault. Using geophysical data for constructing the hydrofacies architecture and using lithologic data for model calibration, the study implements a generalized parameterization indicator scheme. First, the study shows that the methodology can effectively analyze a binary siliciclastic aquifer by depicting the spatial extent of major water bearing units and their interconnections. Second, mapping of the binary fault architecture assists in the assessment of hydraulic continuity across the fault. Third, we use two post-processing techniques to quantify the regional-scale dip, the fault throw and the volumetric spatial extent of individual aquifer units. Results imply that the Baton Rouge fault acts as a leaky-barrier with saltwater intruding the freshwater aquifers through various leaky areas. It was believed that hydraulic continuity through the Denham Springs-Scotlandville fault is due to insignificant sediment offset. However, the study quantitatively shows that there is a considerable fault throw and that the hydraulic continuity occurs due to connection of offset water bearing units.

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013