Woodbine sandstones produce mostly natural gas in stratigraphic traps at Seven Oaks, Hortense, Leggett, and R. B. fields in Polk County, Texas. The Woodbine section can be divided into lower, middle, and nonbioturbated and bioturbated upper units of interbedded sandstones and shales. Strike-trending, pod-shaped concentrations of bioturbated upper sandstones are the principal reservoirs in these fields.

The lower and middle Woodbine sandstones are thinly to thickly bedded and isolated in black, nonbioturbated shales. Thinner sandstones average 0.25 ft (7.5 cm) in thickness and typically consist of more complete turbidite sequences (ABCDE, ABCE, BCE, and CDE). Thicker sandstones that range from 0.5 ft (15 cm) to as much as 7.35 ft (22 m) contain less complete sequences (A, AB, and BC). Thicker sandstones with less complete bedsets represent channel deposits whereas the thinner sandstones with more complete bedsets represent overbank deposits. Thinly bedded, nonbioturbated upper Woodbine sandstones are gradational upward into the thickly bedded, bioturbated sandstones. The nonbioturbated sandstones contain only turbidite bedsets reflecting overbank deposition. Ordered sequences are abs nt in the bioturbated upper sandstones. A few relict, ripple-laminated intervals suggest that the bioturbated sands were deposited by more persistent, low-flow-regime, possibly geostrophic currents, rather than by turbidity currents.

Woodbine clastic deposition is associated with a prograding shelf margin. Electric-log correlation and seismic sections suggest that the lower sandstones were deposited as a group of channel and overbank turbidites on the lower slope. Middle sandstones were deposited in isolated feeder channels located farther up the slope and closer to the shelf break. The thick section of slope shale containing the lower and middle turbidite sandstones is overlain by thinly to thickly bedded upper sandstones interpreted to be shelf-margin sandstones that cap the prograding slope sequence. A turbidite origin for most Woodbine sandstones in the Seven Oaks producing area suggests that channel sandstones associated with submarine fans located farther downdip, possibly over the Sligo reef break, may form extensive dip-trending reservoir bodies.

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