Part 4 - Berg - Hughes Center

10%. Calcite-lined vugs and intergranular openings are the main porosity types.
Permeability likewise is generally low, commonly being less than 0.1 md but reaching as
high as 100 md in small intervals. The hydrocarbons produced are light oils and
condensates, as well as gas in porous limestone intervals. Because of the combination
stratigraphic-structural anomalies present in the area, the James was considered an
excellent exploration target (Hermann, 1976).
Rodessa Formation
Producing Parishes
Caddeo, Bossier, Webster, Claiborne,
Lincoln, Bienvilole, De Soto, Red River
The term Rodessa Formation includes the strata above the James Limestone and
below the base of the Ferry Lake Anhydrite (Roberts and Lock, 1988). The type well for
the formation is located in Rodessa Field, Caddo Parish, Louisiana (Forgotson, 1957). In
the type well, the Rodessa interval is at depths of 5,320 to 5,805 ft. In this part of
Louisiana, the Rodessa Formation consists of oolitic and crystalline limestones, lenticular
fine-grained sandy limestone, anhydrite, coquinoid limestones and gray shales.
Southward from the type area in northwest Louisiana, the limestones of the Rodessa have
reduced porosity and grade into dense, crystalline limestones. The Rodessa siliciclastics
were derived from the craton to the north. Ostracode assemblages in the Rodessa are
typical of open-to-restricted shelf environmental conditions. Yurewicz et al. (1993)
described the Rodessa in east Texas as typically skeletal–peloid-oncoid packstone that
grades downdip into skeletal grainstone and packstone shoals and rudist and coral-red
algae at the platform margin.
370