Sequence Stratigraphy, Lithostratigraphy, and Depositional Dynamics of Lower and Middle Devonian Reservoir Successions, Arkoma Basin
The Lower and Middle Devonian System in the northern Arkoma Basin, Arkansas is represented by two unconformity-bounded units designated the Penters (Lower Devonian) and Clifty Formations (Middle Devonian). The Penters interval produces natural gas in the west-central region of the basin, however, significantly fewer wells are productive from the interval in its thicker development in the eastern basin. Subsurface analysis of the Penters indicates that it is a pervasive deposit of penecontemporaneous chert and fine-grained carbonates. The Penters can be separated into “Lower” and “Upper” intervals by the “Lower Devonian Shale Marker,” which reflects maximum flooding associated with transgression and highstand conditions across a siliciclastic, carbonate-rimmed shelf. Associated chert development mirrors that of the lower Boone Formation (Lower Mississippian) suggesting a volcanic source of the silica and deposition below the sediment-water interface, while the carbonates were still poorly indurated.
The Middle Devonian in the Arkoma Basin was mostly a period of erosion and represented solely by the Clifty Formation. The Clifty, an orthoquartzitic sandstone that was deposited as a lowstand shoreface, is only preserved in the areas where it was incised into the underlying strata. The Clifty is productive in the “Shallow Gas Province” of Northwest Arkansas, however, past practice usually has identified this unit as the Sylamore Sandstone, the basal member of the Chattanooga. Of particular interest, the Arkansas Western Natural Gas Threlkeld #1, in Washington County, Arkansas, has produced more than 1 bcf of gas from the Clifty at a depth of only about 600 feet, and it is still on-line. These stratigraphic relationships are important in recognizing the economic potential of the Lower and Middle Devonian interval in the Arkoma Basin.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009