Part 4 - Berg - Hughes Center

2,000 to 2,500 ft with net pay of 10 to 70 ft. The porosity of the reservoir is from 5 to
25% and permeability can be as high as 500 md (Bebout et al., 1992).
Tertiary Paleocene-Eocene (Midway, Wilcox)
Midway Group
According to Murray (1955), the end of the Cretaceous is characterized by an
interruption of deposition, accompanied by withdrawal of the seas, resulting in a
widespread regional unconformity at the base of the Paleocene in the Coastal Plain
province. Before the Cretaceous seas withdrew, they covered all of the Coastal Plain and
much of the Central Interior of North America. Continued retreat of the early Tertiary
seas in the Coastal Plain area is also evident because of appreciable quantities of later
Midwayan, shallow-water, lignitic, arenaceous to argillaceous, marginal marine deposits.
In outcrops from eastern Texas, Rainwater (1964) identified the Midway as including
shallow marine to moderately deepwater environments consisting of prodeltaic marine
silts and clays that are very carbonaceous and with marine fossils.
Alexander (1935) in a study of well cuttings from wells drilled in southwest
Arkansas and northwest Louisiana was able to identify the Midway section based upon
his correlations of ranges of foraminifera. The only microfossils observed by Alexander
(1935) in the upper, silty, non-calcareous Midway shales of this region are small species
of Ammobaculites and Spiroplectammina. Highly calcareous shales, commonly marly or
chalky in character, and rich in microfauna, are usually encountered within a few feet,
after the first hyaline foraminifera appear. Cores from the Midway in Bossier and
Webster Parishes, Louisiana, were also used to recognize and describe the lower part of
the Midway Group as predominantly calcareous, with true chalk occurring as lenses in
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