Regional geohydrology of the northern Louisiana salt-dome basin, part IV, hydraulic characteristics of the Wilcox-Carrizo aquifer

The Wilcox Group of Paleocene-Eocence age and the Carrizo Sand of Eocene age compose the Wilcox-Carrizo aquifer. Results of 25 aquifer tests and permeability determinations from 43 sidewall cores show that the hydraulic characteristics of the aquifer are variable. Studies of the Carrizo showed that hydraulic conductivity increased as sand-bed thickness increased. Hydraulic conductivity averaged 29 feet per day for sand beds 25 to 100 feet in thickness and 40 feet per day for sand beds 100 to 200 feet in thickness. Based on the aquifer tests and sidewall core analyses, hydraulic conductivity does not increase with increased thickness for the Wilcox part of the aquifer. Permeabilities determined from sidewall cores ranged from less than 1 to more than 3,000 millidarcies (less than 0.002 to more than 7.3 feet per day). Values of hydraulic conductivity determined from aquifer tests ranged from less than 1 to 35 feet per day. (USGS)