The Devon Energy Hull A-102 well, Panola Co., TX, was drilled in January of 2008. A total of 215 feet of conventional core was cut in the Jurassic Haynesville Limestone and Haynesville Shale. In ascending order, the primary rock types in the Haynesville Lime are skeletal lime mudstone/wackestone; dolomitic, argillaceous lime mudstone, and argillaceous limestone. Calcareous shale forms a transition between the Haynesville Limestone and the Haynesville Shale. The shale section is dominated by siliceous shale punctuated by thin intervals of argillaceous limestone.

The matrix of the siliceous shale consists of detrital clays, primarily illite, up to 50% by weight; biogenic and authigenic quartz, 20-47% of the rock; and filaments of marine algal kerogen, 3-8% by volume. The quartz is disseminated throughout the matrix as biogenic quartz, i.e., radiolarian fragments and sponge spicules, and as authigenic microquartz derived from the breakdown and recrystallization of the biogenic quartz.

Interpretation of core and log data within the Haynesville Shale reveals a series of distal 3rd-order depositional sequences that are correlative throughout the basin. The GR log over the lowermost shale interval exhibits a retrogradational stacking pattern with increasing TOC values up to a 3rd-order maximum flooding surface. The GR log of the overlying shale contains a slight progradational stacking pattern up to a 3rd-order sequence boundary representing the base of the Bossier Shale. The overlying Bossier Shale represents a slow progradation of the depositional system to the south and southeast; it is capped by the marginal marine to fluvial Cotton Valley clastic wedge and the Knowles Limestone.

Devon Hull A-102, a comparison of rock, reservoir and chrono-stratigraphic units.