Devillier field is an overpressured gas reservoir producing from upper Vicksburg (lower Oligocene) Loxostoma "B" delicata sands which pinch out near the crest of a structure located on the downthrown side of the Vicksburg flexure. The field is located 50 mi (80 km) east of Houston in northeastern Chambers County, Texas.

A structure map of the lower Frio (upper Oligocene) shows south-southeast regional dip over the field. An isopach map of the upper Vicksburg shows north-northwest dip, and thickening of sands and shales into the Vicksburg flexure northwest of the field. Correlation of stratigraphic units indicates maximum growth across the flexure during upper Vicksburg deposition. Based on analysis of composition, sorting, and grain size of detrital minerals and quartz from cores and cuttings, the field pay, the Loxostoma sand, is interpreted to have been deposited as a delta distributary mouth bar sand. Pinchout of this sand facies against a prodelta shale facies has resulted in creation of a true stratigraphic trap.

The first year's production per well averaged 1.0 Bcf gas and 13,000 bbl condensate for the seven wells completed since the field discovery in 1975. Calculated open flows have ranged as high as 600,000 Mcf/day gas from an average net-sand interval of 25 ft (7.6 m) at depths between 10,550 and 10,750 ft (3,216 and 3,277 m). Most of the remaining undiscovered reserves in mature petroleum provinces will be found in similarly small, but significant and economic subtle traps.