Depositional Model and Diagenetic History of Frisco Formation (Lower Devonian) in Central Oklahoma

Patrick L. Medlock

The Lower Devonian Frisco Limestone is a prolific reservoir within the Hunton Group. The giant Fitts and West Edmond fields produce from the Frisco, as do other small fields in the eastern Anadarko basin, central Oklahoma, and western Arkoma basin. A crinoidal-mud-mound complex is the inferred depositional model, based on geometry and lithotypes. Mound growth was probably initiated on paleostructural highs. Facies in the mud-mound complex include mound-core, flank/intermound, and mound-crest. The mound-core facies, consisting of poorly sorted wackestones and mudstones, formed as thickets of crinoid-baffled lime mud. The flank/intermound facies, which is moderately sorted packstones, formed in areas of low crinoid population, allowing current activity to winnow much of the lime mud to form carbonate sand. The mound-crest facies, which is predominantly grainstones with some packstones, was deposited as a sand sheet as the mound reached active wave base.

Unlike the dolomitized reservoirs of other Hunton formations, the Frisco is a limestone reservoir that underwent an intricate, multiphase, diagenetic history. Although secondary porosity developed during subaerial exposure, depositional facies exhibited considerable control on porosity distribution. Solution-enhanced primary porosity and secondary vuggy porosity are the most significant types.

AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.