RESERVOIR POTENTIAL OF THE UPPER JACKFORK SANDSTONE (LOWER PENNSYLVANIAN), WESTERN OUACHITA REGION, ARKANSAS

The upper Jackfork Sandstone (Lower Pennsylvanian) in the frontal Ouachita Mountains of west-central Arkansas represents sand-dominated distal flysch deposition reflecting axial delivery along the compressing Ouachita trough. Exposures in Scott County, Arkansas, were measured, and sampled for permeability, porosity, and standard petrographic analysis. In addition, synthetic gamma ray logs were constructed from the same exposures to provide a basis for regional correlation. The lithologic data demonstrate that the upper Jackfork sandstones are mostly quartz arenites (grain densities typically 2.65)possessing consistently low porosites, typically less than 4%, and average permeabilities below .005 milledarcies (Klinkenberg). In contrast, the sandstones are highly fractured as a result of their near vertical uplift in response to the Ouachita orogeny. This relationship suggests potential for horizontial drilling should the presence of hydrocarbons be detected. The Potato Hills, Latimer County, Oklahoma, includes hydrocarbon production from both the Arkansas Novaculite and the upper Jackfork Sandstone providing an analogue and some encouragement for further exploration of adjacent western Arkansas.