Part 4 - Berg - Hughes Center

Across northern Louisiana in the producing fields of Bienville, Richland, Franklin,
Tensas and Concordia Parishes, the Tuscaloosa consists of fine- to coarse-grained quartz
arenites and fossiliferous clays, ashy sands, red beds, gray shales, and minor chert gravels
deposited in fluvial-deltaic to shallow marine environments. Generally, the Tuscaloosa is
overlain by the shaly Eagle Ford Formation that averages approximately 100 ft in
thickness (Lenert and Kidda, 1958; Morrow, 1958; Rogers, 1958). Production is from the
basal sandstones of the lower Tuscaloosa where net porous sand ranges from 90 to 250 in
thickness (Cullom et al., 1962). Depth to the top of the sandstone reservoirs across the
region ranges from 2,400 to 9,700 ft. Production of 24º to 46º API gravity oil,
condensate, and gas is derived from quality reservoirs with porosities of 25 to 30% and
permeabilities ranging from 200 to 2,000 md.
Austin Group
Producing Parishes
Caddo, Bossier, Webster,
Claiborne, Union
The basal sediments of the Austin Group were deposited over a truncated surface of
the Tuscaloosa Group (Forgotson, 1958a). In north Louisiana, the Austin Group includes
the Brownstown and Tokio formations, with a thickness that ranges from zero on the
Monroe Uplift to over 2,000 ft in Central Louisiana (Cullom et al., 1962). These shallow
marine deposits consist mainly of medium- to coarse-grained glauconitic carbonaceous
and argillaceous sandstone and alternating chalky, shaly and silty units. Carbonates that
replace the sands and shales to the south typically are chalk or marl and have poor
definition on well logs. Ogier (1963) described the Tokio Formation as consisting of
coarse, gray and brown crossbedded quartz and dark gray lignitic fossiliferous clay. In
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